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Paulino CA, Marler TE. Nitrogen and Carbon Mineralization from Green and Senesced Leaf Litter Differ between Cycad and Angiosperm Trees. Biology (Basel) 2022; 11:biology11121758. [PMID: 36552268 PMCID: PMC9775132 DOI: 10.3390/biology11121758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/24/2022] [Accepted: 12/01/2022] [Indexed: 12/07/2022]
Abstract
Plant leaf litter decomposition is directly influenced by the identity of the source plants and the leaf age. Defoliation of forests by tropical cyclones (TC) transfers copious amounts of high-quality green leaf litter to soils. We used a soil amendment approach with the incubated buried bag method to compare carbon (C) and nitrogen (N) mineralization dynamics of green and senesced leaf litter from cycad Cycas micronesica and angiosperm Morinda citrifolia trees on the island of Guam. Soil priming increased the decomposition of pre-existing organic C, and were greater for green leaf litter additions than senesced leaf litter additions. Available N content increased by day 14 and remained elevated for the entire 117-d incubation for soils amended with green M. citrifolia litter. In contrast, available N content increased above those in control soils by day 90 and above those in soils amended with senesced litter by day 117 for green C. micronesica litter. The net N mineralization rate was higher than control soils by 120% for the senesced litter treatments and 420% for the green litter treatments. The results reveal a complex but predictable interplay between TC defoliation and litter quality as defined by tree identity. We have illuminated one means by which increased frequency of intense TCs due to climate change may alter the global C and N cycles.
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Affiliation(s)
- Charles A. Paulino
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, Mangilao, GU 96923, USA
| | - Thomas E. Marler
- Bagong Kaalaman Botanikal Institute, 15 Rizal Street, Barangay Malabañas, Angeles City 2009, Philippines
- Correspondence:
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Marler TE, Shaw CA. Metals and Metalloids Increase in Cycas micronesica Seed Gametophyte Tissue in Shaded Growth Conditions. Toxics 2022; 10:550. [PMID: 36287831 PMCID: PMC9609483 DOI: 10.3390/toxics10100550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/16/2022] [Accepted: 09/18/2022] [Indexed: 06/16/2023]
Abstract
Exposure to environmental toxins may be partly responsible for mammal neurodegenerative disorders. Consumption of seeds from Guam's cycad tree has been linked to the disorder known as amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC). The unambiguous identification of causal agents of ALS-PDC has been elusive. We have examined the levels of eight metals and metalloids in cycad seeds as a function of the ambient shade in which the plants were grown. Of these metals, the data strongly suggest that aluminum (Al) and selenium (Se) are present in washed flour prepared from southern Guam's cycad seed tissues at elevated levels, especially when the trees are grown in shade. Previous authors have speculated that Al and Se are involved in various ALS outcomes, and our results support this interpretation.
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Affiliation(s)
- Thomas E. Marler
- Bagong Kaalaman Botanikal Institute, 15 Rizal Street, Barangay Malabañas, Angeles City 2009, Philippines
| | - Christopher A. Shaw
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
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Marler TE, Cruz GN. Temporal Variation of Litterfall and Nutrient Return of Serianthes nelsonii Merr. in a Tropical Karst Forest. Plants (Basel) 2022; 11:2310. [PMID: 36079692 PMCID: PMC9459683 DOI: 10.3390/plants11172310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/16/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
Trees contribute to ecosystem nutrient cycling through the amount, timing, and composition of litterfall. Understanding the nature of this contribution from endangered tree species may aid in species and habitat recovery efforts. Serianthes nelsonii is an endangered tree species from the Mariana Islands, and little is known about litterfall dynamics. The timing of leaf, fruit, and stem litterfall was determined to more fully understand the return of nutrients via litter. The total annual litterfall was 272.8 g·m−2, with 45% represented by leaves, 48% represented by stems, and 7% represented by fruits. Stem litterfall weight contrasted more from month to month than the other organs, and leaf litterfall exhibited the most even distribution throughout the year. The timing of fruit and stem litterfall was influenced by the timing of extreme wind events. Leaf litter contributed nutrients in the following order: carbon > calcium > nitrogen > potassium > magnesium > iron > phosphorus > manganese > boron > zinc > copper. Fruit and stem litter contributed nutrients in the following order: carbon > calcium > nitrogen > magnesium > potassium > phosphorus > iron > manganese > boron > zinc > copper. Based on carbon/nitrogen, the stem litter exhibited the lowest quality and leaf litter exhibited the highest quality for speed of nutrient release via decomposition. Conservationists may use this knowledge to more fully integrate S. nelsonii trees into habitat management plans.
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Affiliation(s)
- Thomas E. Marler
- Bagong Kaalaman Botanikal Institute, 15 Rizal Street, Barangay Malabañas, Angeles City 2009, Philippines
| | - Gil N. Cruz
- Western Pacific Tropical Research Center, University of Guam, Mangilao, GU 96923, USA
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Liu J, Lindstrom AJ, Marler TE, Gong X. Not that young: combining plastid phylogenomic, plate tectonic and fossil evidence indicates a Palaeogene diversification of Cycadaceae. Ann Bot 2022; 129:217-230. [PMID: 34520529 PMCID: PMC8796677 DOI: 10.1093/aob/mcab118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/10/2021] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Previous molecular dating studies revealed historical mass extinctions and recent radiations of extant cycads, but debates still exist between palaeobotanists and evolutionary biologists regarding the origin and evolution of Cycadaceae. METHODS Using whole plastomic data, we revisited the phylogeny of this family and found the Palawan endemic Cycas clade was strongly related to all lineages from Southeast Eurasia, coinciding with a plate drift event occurring in the Early Oligocene. By integrating fossil and biogeographical calibrations as well as molecular data from protein-coding genes, we established different calibration schemes and tested competing evolutionary timelines of Cycadaceae. KEY RESULTS We found recent dispersal cannot explain the distribution of Palawan Cycas, yet the scenario including the tectonic calibration yielded a mean crown age of extant Cycadaceae of ~69-43 million years ago by different tree priors, consistent with multiple Palaeogene fossils assigned to this family. Biogeographical analyses incorporating fossil distributions revealed East Asia as the ancestral area of Cycadaceae. CONCLUSIONS Our findings challenge the previously proposed Middle-Late Miocene diversification of cycads and an Indochina origin for Cycadaceae and highlight the importance of combining phylogenetic clades, tectonic events and fossils for rebuilding the evolutionary history of lineages that have undergone massive extinctions.
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Affiliation(s)
- Jian Liu
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- For correspondence. Email , or
| | - Anders J Lindstrom
- Global Biodiversity Conservancy, 144/124 Moo3, Soi Bua Thong, Bangsalae, Sattahip, Chonburi 20250, Thailand
- For correspondence. Email , or
| | - Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, GU 96923, USA
| | - Xun Gong
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- For correspondence. Email , or
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Abstract
Growth dynamics of pachycaulous stems of arborescent cycad plants are not well understood, and most observations have been made in cultivated garden plants. We studied Cycas micronesica plants in Guam, Tinian, and Yap to understand the influences of geography, plant size, sex, and herbivory on stem growth. We also determined the changes in demography of Guam's population after 15 years of damage by non-native insect herbivores. The height increment (HI) was similar for plants within the height range from 100 cm to more than 600 cm, so the relative growth rate declined with height. Female tree HI was 68% of male tree HI, and Yap tree HI was 87% of Guam tree HI. Chronic herbivory by non-native insect herbivores caused a mean 44% decline in HI. Plants in managed gardens grew more rapidly than plants in a wild habitat. The HI was used to estimate that Guam has experienced a complete loss of ≈70 y of demographic depth resulting from the selective mortality of small plants since 2005. When future conservation interventions successfully mitigate the ubiquitous biological threats, our HI may be useful for empirically quantifying recovery of plant health.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam, USA
- CONTACT Thomas E. Marler Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam96923, USA
| | | | - Murukesan V. Krishnapillai
- Cooperative Research and Extension, College of Micronesia-FSM, Yap Campus, Yap, Federated States of Micronesia
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Deloso BE, Marler TE. Bi-Pinnate Compound Serianthes nelsonii Leaf-Level Plasticity Magnifies Leaflet-Level Plasticity. Biology (Basel) 2020; 9:E333. [PMID: 33066001 PMCID: PMC7600808 DOI: 10.3390/biology9100333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/16/2020] [Accepted: 09/20/2020] [Indexed: 11/20/2022]
Abstract
Numerous leaf traits exhibit developmental plasticity in response to irradiance, an attribute that maximizes performance in the prevailing light. The use of leaflets to represent whole leaf traits of tree species with compound leaves is common in the acclimation literature. These methods ignore the potential for whole leaf plasticity to augment leaflet plasticity. We grew Serianthes nelsonii plants in incident light ranging from 6% to 100% of sunlight and quantified numerous leaflet and leaf traits to determine plasticity index (PI: (maximum-minimum)/maximum)) of each. Leaflet acclimation such as changes in length of palisade mesophyll occurred as expected. However, leaf-level morphometric traits such as rachillae insertion angle also exhibited acclimation potential. The leaf-level plastic behavior enabled acclimation approaches that simple-leaved species do not possess. We illuminate the need to look at the entire leaf when quantifying acclimation potential of tree leaves, and indicate that the historical use of leaflets to represent species with compound leaves under-estimated the acclimation potential when compared to species with simple leaves.
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Affiliation(s)
| | - Thomas E. Marler
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, GU 96923, USA;
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Abstract
An understanding of leaf nutrient relations is required for tree conservation and horticulture success. The study of cycad leaf nutrient dynamics has expanded in recent years, but direct comparisons among reports remains equivocal due to varying sampling protocols. We used Cycas micronesica K.D. Hill and Cycas nongnoochiae K.D. Hill trees to determine the influence on leaf nutrient concentrations of in situ versus ex situ locations and orientation of leaves within the tree canopy. Nitrogen, phosphorus, and potassium concentrations of leaves from ex situ plants exceeded those from in situ plants, and the differences were not explained by soil nutrient differences. Calcium concentrations of leaves varied among the site pairs, with differences primarily explained by soil calcium. Magnesium concentrations of leaves were not different among all location pairs even though soil magnesium concentrations varied among the sites more than any of the other elements. Differences in leaf macronutrient concentrations among four C. micronesica provenances were minimal when grown in a common garden. Lateral orientation of leaves did not influence any of the essential elements for either of the species. These findings indicate that the lateral orientation of cycad leaves does not influence leaf nutrient concentrations, leaf nutrient relations of cycad plants in managed ex situ settings do not align with leaf nutrient relations in habitat, and these differences are not explained by soil nutrition for most elements. We suggest that leaf nutrient concentrations should be determined in all niche habitats within the geographic range of a cycad species in order to fully understand the leaf physiology of each species.
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Marler TE. Artifleck: The Study of Artifactual Responses to Light Flecks with Inappropriate Leaves. Plants (Basel) 2020; 9:plants9070905. [PMID: 32708982 PMCID: PMC7412511 DOI: 10.3390/plants9070905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 06/30/2020] [Accepted: 07/08/2020] [Indexed: 12/25/2022]
Abstract
Methods in sunfleck research commonly employ the use of experimental leaves which were constructed in homogeneous light. These experimental organs may behave unnaturally when they are challenged with fluctuating light. Photosynthetic responses to heterogeneous light and leaf macronutrient relations were determined for Cycas micronesica, Glycine max, and Zea mays leaves that were grown in homogeneous shade, heterogeneous shade, or full sun. The speed of priming where one light fleck increased the photosynthesis during a subsequent light fleck was greatest for the leaves grown in heterogeneous shade. The rate of induction and the ultimate steady-state photosynthesis were greater for the leaves that were grown in heterogeneous shade versus the leaves grown in homogeneous shade. The leaf mass per area, macronutrient concentration, and macronutrient stoichiometry were also influenced by the shade treatments. The amplitude and direction in which the three developmental light treatments influenced the response variables were not universal among the three model species. The results indicate that the historical practice of using experimental leaves which were constructed under homogeneous light to study leaf responses to fluctuating light may produce artifacts that generate dubious interpretations.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, Mangilao, GU 96923, USA
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Abstract
Guam’s established population of non-native coconut rhinoceros beetle (CRB, Oryctes rhinoceros L.) began creating burrows in stem apices of several cycad species in a managed garden. We conducted an island-wide survey to determine the spatial patterns of CRB burrowing of stems of in situ Cycas micronesica. We also measured starch of healthy and unhealthy coconut leaf tissue and compared this with starch of cycad stem tissue. The starch concentration of the central unexpanded leaf in healthy Philippine coconut trees was ≈90 mg·g−1, and that of unhealthy Guam coconut trees was ≈40 mg·g−1. The starch concentration of the tissue within the CRB burrow locations on C. micronesica trees was 145 mg·g−1. Burrowing of C. micronesica was restricted to female CRB adults and was found throughout the full latitudinal gradient of Guam. Our findings indicate Guam’s unhealthy coconut trees are no longer nutrient-dense, and the female CRB population may have exhibited a phylogenetically distant host shift to the abundant C. micronesica plants for a starch-rich diet within the concepts of the ‘ecological fitting’ hypothesis. We add proximity to coconut tree habitats as a new threat to Guam’s endangered C. micronesica population.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, GU, USA
| | - Frankie C Matanane
- Western Pacific Tropical Research Center, University of Guam, Mangilao, GU, USA
| | - L Irene Terry
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
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Marler TE, Cruz GN. Cycas micronesica Stem Carbohydrates Decline Following Leaf and Male Cone Growth Events. Plants (Basel) 2020; 9:plants9040517. [PMID: 32316630 PMCID: PMC7238054 DOI: 10.3390/plants9040517] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/03/2020] [Accepted: 04/14/2020] [Indexed: 05/16/2023]
Abstract
The growth of synchronized leaf flushes or male cones on Cycas trees is an ephemeral event, and non-structural carbohydrates (NSCs) are likely deployed from stem and root storage tissues to support their construction. The relationships among various stem NSCs and these rapid growth events have not been studied to date. Monosaccharides, disaccharides, and starch were quantified in Cycas micronesica stem tissue prior to and immediately after the growth of leaf flushes or male cones to determine the influences on the concentration of these carbohydrates. The pre-existing leaves were removed from half of the plants to determine if the elimination of this carbon source would influence the NSC behaviors. Starch and sucrose dominated the NSC profiles, and these two NSCs declined following cone or new leaf growth. Removal of pre-existing leaves generated a greater decline in starch and sucrose for cone growth, and a greater decline in sucrose, but not starch following new leaf growth than in control trees with no leaf removal. The initial differences in starch and sucrose among cortex, vascular, and pith tissues disappeared as the concentrations declined in all three tissue categories to reach similar post-growth concentrations among the stem tissue categories. The fructose, glucose, and maltose behaviors were not consistent, and their concentrations were low such that their influence on the total NSC behaviors was minimal. These results provided indirect evidence that stem NSCs were mobilized to support ephemeral male cone and new leaf growth for this arborescent cycad. Growth of female strobili is slow and lengthy, so we did not include female trees in this study. The contributions of stem NSCs to female strobili growth remain to be studied with alternative methods.
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Marler TE, Lindström AJ. Diel patterns of stem CO 2 efflux vary among cycads, arborescent monocots, and woody eudicots and gymnosperms. Plant Signal Behav 2020; 15:1732661. [PMID: 32100615 PMCID: PMC7194385 DOI: 10.1080/15592324.2020.1732661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/13/2020] [Accepted: 02/15/2020] [Indexed: 05/28/2023]
Abstract
The diel patterns of stem carbon dioxide efflux (Es) were determined for cycads, monocots, and woody eudicot and gymnosperm tree species. Stem Es at a height of 30-40 cm was measured every 2 h throughout 31-h campaigns. Our range of Es was 1.5-4.0 µmol·m-2·s-1 for cycads, 1.0-3.5 µmol·m-2·s-1 for arborescent monocots, and 1.5-4.5 µmol·m-2·s-1 for woody eudicot and gymnosperm trees species. Time of day did not influence Es of cycads or monocots. In contrast, the woody stems of eudicots and gymnosperms exhibited diurnal Es that was 36% to 40% greater than nocturnal Es. The established literature based on Es of woody tree species cannot be used to estimate habitat carbon cycles in habitats which contain cycad or monocot trees. Time of day must be included for accuracy of research on Es of woody tree species. Failures to account for the spatiotemporal differences of Es may explain some of the disparity in outcomes of published stem respiration studies.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam, USA
| | - Anders J. Lindström
- Plant Collections Department, Nong Nooch Tropical Botanical Garden, Sattahip, Thailand
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Marler TE, Krishnapillai MV. Vertical Strata and Stem Carbon Dioxide Efflux in Cycas Trees. Plants (Basel) 2020; 9:E230. [PMID: 32054006 PMCID: PMC7076351 DOI: 10.3390/plants9020230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/02/2020] [Accepted: 02/09/2020] [Indexed: 11/16/2022]
Abstract
Stem respiration is influenced by the vertical location of tree stems, but the influence of vertical location on stem respiration in a representative cycad species has not been determined. We quantified the influence of vertical strata on stem carbon dioxide efflux (Es) for six arborescent Cycas L. species to characterize this component of stem respiration and ecosystem carbon cycling. The influence of strata on Es was remarkably consistent among the species, with a stable baseline flux characterizing the full mid-strata of the pachycaulous stems and an increase in Es at the lowest and highest strata. The mid-strata flux ranged from 1.8 µmol·m-2·s-1 for Cycas micronesica K.D. Hill to 3.5 µmol·m-2·s-1 for Cycas revoluta Thunb. For all species, Es increased about 30% at the lowest stratum and about 80% at the highest stratum. A significant quadratic model adequately described the Es patterns for all six species. The increase of Es at the lowest stratum was consistent with the influence of root-respired carbon dioxide entering the stem via sap flow, then contributing to Es via radial conductance to the stem surface. The substantial increase in Es at the highest stratum is likely a result of the growth and maintenance respiration of the massive cycad primary thickening meristem that constructs the unique pachycaulous cycad stem.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam 96923, USA
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Marler TE. Stem CO 2 efflux of Cycas micronesica is reduced by chronic non-native insect herbivory. Plant Signal Behav 2020; 15:1716160. [PMID: 31985317 PMCID: PMC7053932 DOI: 10.1080/15592324.2020.1716160] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 05/28/2023]
Abstract
Carbon dioxide efflux (Es) from the base of Cycas micronesica K.D. Hill stems was quantified in four locations containing healthy populations and in one location with populations threatened by non-native insect herbivores in order to determine the influence of reduced plant health on Es. Minimal variation of Es occurred among the four locations with healthy plants, and Es ranged from 1.68 to 1.79 µmol·m-2·s-1. The threatened in situ populations were on the island of Guam, where recent invasions of non-native insects have caused epidemic plant mortality, and the Es was 0.59 µmol·m-2·s-1. This is the first known report of Es for any cycad species, and the values for the unique pachycaulous stem form fit in the lower half of the range of published Es for woody trees. The results illuminate the potential for using Es to screen in situ C. micronesica populations to identify the individual trees with the greatest likelihood of surviving conservation measures.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam, USA
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Abstract
The soils beneath and surrounding mature Artocarpus mariannensis, Elaeocarpus joga, and Serianthes nelsonii trees were studied in northern Guam limestone forests to determine the role of these trees in maintaining spatial heterogeneity of biogeochemistry. The soils beneath S. nelsonii were nutrient-enriched compared to soils away from S. nelsonii. The soils beneath A. mariannensis were depauperate for some nutrients or were not different from the soils away from A. mariannensis for other nutrients. The soils beneath E. joga exhibited increases in some nutrients such as nitrogen, carbon, and phosphorus, but decreases in other nutrients such as potassium and calcium when compared to the soils away from E. joga trees. These three tree species influenced spatial heterogeneity in soil nutrient status in the order A. mariannensis < E. joga < S. nelsonii and their presence added greatly to surface soil heterogeneity. Iron, manganese, and pH exhibited the least variation within the paired sites. Calcium, magnesium, potassium, and zinc exhibited the greatest variation among the paired sites. These findings indicate that continuing loss of these trees from Guam’s forests will diminish the associated biogeochemical spatial heterogeneity.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam, USA
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Marler TE. Repetitive pruning of Serianthes nursery plants improves transplant quality and post-transplant survival. Plant Signal Behav 2019; 14:1621246. [PMID: 31131690 PMCID: PMC6619948 DOI: 10.1080/15592324.2019.1621246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 05/16/2019] [Accepted: 05/16/2019] [Indexed: 06/09/2023]
Abstract
Information on the best methods for producing endangered Serianthes nelsonii plants for use in species recovery projects is lacking. Plants of this species behave similarly in a nursery setting to plants of the congeneric Serianthes grandiflora and Serianthes kanehirae. Container-grown plants of these two species were repeatedly pruned in the nursery to determine if a more favorable root:shoot ratio would result, then to determine if performance after out-planting would benefit from the enhanced root growth. Repetitive pruning increased absolute root dry weight 43% to 61% and root:shoot ratio 55% to 56% above that of control plants that were not pruned. One year after out-planting, the pruned plants were greater in shoot dry weight and plant height than the control plants. More importantly, control plants exhibited 70% to 80% mortality, but the pruned plants exhibited 100% survival. This new knowledge from two surrogate species indicated that repetitive pruning of S. nelsonii plants in conservation nurseries would greatly increase the quality of the resulting transplants and therefore nurseries may add pruning as a prescribed production protocol to improve species recovery success.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam
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Marler TE. Temperature and Imbibition Influence Serianthes Seed Germination Behavior. Plants (Basel) 2019; 8:plants8040107. [PMID: 31010091 PMCID: PMC6524026 DOI: 10.3390/plants8040107] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 11/25/2022]
Abstract
The direct role of physical dormancy in delaying germination of Serianthes grandiflora Bentham, Serianthes kanehirae Fosberg, and Serianthes nelsonii Merrill seeds has not been adequately studied, nor has the role of temperature on germination behaviors. Imbibition testing indicated seeds with scarified testa absorbed water for the duration of a 24 h imbibition period, but seeds with an intact testa stopped absorbing water after 1 h. The behavior of S. nelsonii seeds most closely matched those of S. kanehirae, with the pattern of water absorption for S. grandiflora seeds deviating from that for the other species. Scarified seeds germinated readily, with initial germination occurring by 50 h for S. nelsonii and 90 hr for the other species, and maximum germination of 80% to 90% occurring by 60 h for S. nelsonii and 100 h for the other species. Predicted optimum temperature based on a fitted quadratic model was 26 °C for S. nelsonii, 23 °C for S. grandiflora, and 22 °C for S. kanehirae. Seed respiration increased within 3 h of imbibition for scarified seeds and continued to increase in a linear pattern. The linear slope was greatest for S. nelsonii, intermediate for S. grandiflora, and least for S. kanehirae, but ultimate respiration was greatest for S. kanehirae seeds. Seed respiration was so limited for un-scarified seeds that the instrument was unable to quantify any carbon dioxide efflux. Physical dormancy in seeds of these Serianthes species is a powerful trait that spreads out the timing of seedling emergence in natural settings and controls imbibition and germination speed in managed nurseries.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, Guam 96923, USA.
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Marler TE. Thigmomorphogenesis and biomechanical responses of shade-grown Serianthes nelsonii plants to stem flexure. Plant Signal Behav 2019; 14:1601953. [PMID: 30985234 PMCID: PMC6619927 DOI: 10.1080/15592324.2019.1601953] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 04/01/2019] [Accepted: 03/26/2019] [Indexed: 06/09/2023]
Abstract
The influences of stem flexure on shade-grown Serianthes nelsonii Merr. stem growth and strength were determined in a container nursery setting. Treated stems were bent 90° two times daily for a 14 wk nursery production period. Plant height, internode length, and slenderness were decreased by stem flexure when compared with control plants that received no flexure. Two force-displacement tests revealed stem strength was increased by the flexure treatment. Control plants exhibited undesirable lean of the main stem, and 1 hr of wind stress further increased the angle of lean. Treated plants were close to orthotropic and the wind stress did not change the stem lean. Results indicate stem flexure is a reliable method for increasing the quality of shade-grown S. nelsonii plants and some form of mechanical stimulation should be added to nursery production protocols for the species.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, USA
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Marler TE. Tree conservation can be constrained by agents from conservation permitting and funding agencies. Commun Integr Biol 2019; 12:133-143. [PMID: 31528243 PMCID: PMC6735646 DOI: 10.1080/19420889.2019.1654348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 08/06/2019] [Indexed: 11/15/2022] Open
Abstract
Recent conservation actions for Serianthes nelsonii Merr. and Cycas micronesica K.D. Hill in the Mariana Islands have illuminated some negative consequences associated with ill-informed agents representing permitting and funding agencies. Several cases from the islands of Guam and Tinian are discussed as ineffective conservation examples, and these are countered with two examples of successful conservation approaches. When biologists that act as points of contact for federal permitting and funding agencies do not possess education, knowledge, and experience that is germane to federally listed species, sound science may be marginalized from the conservation agenda. When rapid turnover of federal conservation agents introduces dysfunction, discontinuities in collaborations may thwart success. When lapses in conservation contracts are allowed, short-term extemporary contracting approaches are utilized, and conservation practitioners that lack the ability to include an experimental approach to conservation actions are employed, the co-production of new knowledge to enable decision support tools for future decision-makers may be hindered.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam, USA
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Marler TE, Marler PN. Rhyzobius lophanthae Behavior is Influenced by Cycad Plant Age, Providing Odor Samples in a Y-tube Olfactometer. Insects 2018; 9:insects9040194. [PMID: 30567297 PMCID: PMC6315894 DOI: 10.3390/insects9040194] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/12/2018] [Accepted: 12/17/2018] [Indexed: 12/02/2022]
Abstract
The scale predator Rhyzobius lophanthae Blaisdell was introduced to Guam and Rota to control invasive Aulacaspis yasumatsui Takagi armored scale infestations on the native Cycas micronesica K.D. Hill populations. The predator demonstrated a clear preference for A. yasumatsui infesting adult plants, resulting in 100% seedling mortality due to the lack of a biocontrol of the scale on seedlings. A Y-tube olfactometer was employed to determine if scale-infested seedling leaves were less attractive to R. lophanthae than scale-infested mature tree leaves. Five paired combinations of seedling versus mature tree leaves were used. The R. lophanthae adults navigated toward scale-infested and un-infested leaves of adults and seedlings when paired with an empty chamber. However, a clear preference for adult leaves occurred when paired with seedling leaves. The results were unambiguous in charcoal-filtered air, intermediate in unfiltered air from an open laboratory, and most ambiguous when conducted with unfiltered in-situ air. The number of predators that did not make a choice was greatest for in-situ air and least for charcoal-filtered air. These results indicated that the substrate used in olfactometry influenced the results, and interpretations of charcoal-filtered air assays should be made with caution. Volatile chemical cues are involved in R. lophanthae preferring A. yasumatsui located on C. micronesica adults when infested adult and seedling leaves are present.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, Guam 96923, USA.
| | - Paris N Marler
- Centre for Sustainability PH, Inc., PENRO Road, Puerto Princesa, Palawan 5300, Philippines.
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Marler TE, Krishnapillai MV. Does Plant Size Influence Leaf Elements in an Arborescent Cycad? Biology (Basel) 2018; 7:E51. [PMID: 30551676 PMCID: PMC6315973 DOI: 10.3390/biology7040051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/06/2018] [Accepted: 12/11/2018] [Indexed: 11/16/2022]
Abstract
Plant size influences the leaf nutrient relations of many species, but no cycad species has been studied in this regard. We used the arborescent Cycas micronesica K.D. Hill to quantify leaf nutrient concentrations of trees with stems up to 5.5-m in height to determine if height influenced leaf nutrients. Green leaves were sampled in a karst, alkaline habitat in Rota and a schist, acid habitat in Yap. Additionally, senesced leaves were collected from the trees in Yap. Minerals and metals were quantified in the leaf samples and regressed onto stem height. Green leaf nitrogen, calcium, manganese, and iron decreased linearly with increased stem height. Senesced leaf carbon, iron, and copper decreased and senesced leaf nitrogen increased with stem height. Nitrogen resorption efficiency decreased with stem height. Phosphorus and potassium resorption efficiencies were not influenced by plant size, but were greater than expected based on available published information. The results indicate leaf nutrient concentrations of this cycad species are directly influenced by plant size, and illuminate the need for adding more cycad species to this research agenda. Plant size should be measured and reported in all cycad reports that include measurements of leaf behavior.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam 96923, USA.
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Marler TE, Lindström AJ. Inserting cycads into global nutrient relations data sets. Plant Signal Behav 2018; 13:e1547578. [PMID: 30444181 PMCID: PMC6296355 DOI: 10.1080/15592324.2018.1547578] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 11/07/2018] [Indexed: 05/27/2023]
Abstract
Global research agendas on plant nutrient relations attempt to illuminate biotic and abiotic factors that mediate nutrient relations. We contend that cycad species are not adequately represented in these global agendas. Little is known about how various cycad traits such as phylogenetics, growth form, latitudinal range, or ecological niche influence concentration, stoichiometry, and resorption dynamics of leaf nutrients. The addition of cycad species data to the global research dataset will address a critical knowledge gap and benefit global research needs to improve our systemic understanding of biotic and abiotic influences on plant nutrition.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam, USA
| | - Anders J. Lindström
- Plant Collections Department, Nong Nooch Tropical Botanical Garden, Sattahip, Thailand
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Marler TE. Elemental Profiles in Cycas micronesica Stems. Plants (Basel) 2018; 7:plants7040094. [PMID: 30388771 PMCID: PMC6313939 DOI: 10.3390/plants7040094] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/28/2018] [Accepted: 10/30/2018] [Indexed: 05/28/2023]
Abstract
Essential nutrients and metals have been quantified in stems of many tree species to understand the role of stems as storage and source organs. Little is known about stored stem resources of cycad tree species. Cycas micronesica tissue was collected from apical and basal axial regions of stems; and pith, vascular, and cortex tissues were separated into three radial regions. Leaves were also sampled to provide a comparison to stems. Minerals and metals were quantified in all tissues. Minerals and metals varied greatly among the six stem sections. Phosphorus varied more among the three radial sections than the other macronutrients, and zinc and nickel varied more than the other micronutrients. Stem carbon was less than and stem calcium was greater than expected, based on what is currently known tree stem concentrations in the literature. Elemental concentrations were generally greater than those previously reported for coniferous gymnosperm trees. Moreover, the stem concentrations were high in relation to leaf concentrations, when compared to published angiosperm and conifer data. The results indicated that the addition of more cycad species to the literature will improve our understanding of gymnosperm versus angiosperm stem nutrient relations, and that the non-woody cycad stem contains copious essential plant nutrients that can be mobilized and deployed to sinks when needed.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, Guam 96923, USA.
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Marler TE. Leaf Damage by Phytophagous Beetles alters Terminalia catappa Green and Senesced Leaf Chemistry. Int J Insect Sci 2018; 10:1179543318797329. [PMID: 30186031 PMCID: PMC6117864 DOI: 10.1177/1179543318797329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/07/2018] [Indexed: 06/08/2023]
Abstract
Chemical traits of Terminalia catappa L. leaves were determined on the island of Guam to understand the changes caused by beetle leaf herbivory. Green leaf chemistry indicated nitrogen was the most limiting nutrient in the climate and soils of Guam. The changes in leaf chemistry following beetle damage were extensive. Senesced leaf chemistry indicated beetle damage decreased some traits that predict lower leaf litter quality, such as lignin, but also decreased some traits that predict higher leaf litter quality, such as nitrogen. The stoichiometric traits based on carbon:macronutrient and lignin:macronutrient generally predicted higher quality leaf litter following beetle herbivory. The beetles that produce this form of T. catappa leaf damage on Guam are non-native, and overall, the results indicate these pests will increase the rate of litter decomposition and nutrient turnover in habitats where T. catappa is prevalent.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam
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Marler TE. Axial and Radial Spatial Patterns of Non-Structural Carbohydrates in Cycas micronesica Stems. Plants (Basel) 2018; 7:E49. [PMID: 29932150 PMCID: PMC6161113 DOI: 10.3390/plants7030049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 11/18/2022]
Abstract
The pachycaulous stem of arborescent cycad species exhibits unique traits and has received limited research. To date, nothing is known about the axial and radial spatial patterns of non-structural resources within cycad stems. Cycas micronesica K.D. Hill stem tissue was collected from apical and basal axial positions of ca. 100-cm tall plants to serve as two axial regions; and from pith, vascular, and cortex tissues to serve as three radial regions. Starch and four free sugars were quantified. These stems contained more starch than any of the individual sugars, and sucrose concentration exceeded that of fructose and glucose, which exceeded that of maltose. Total non-structural carbohydrate was least in basal vascular tissue (225 mg·g−1) and greatest in apical pith tissue (379 mg·g−1). Axial differences in NSC concentrations were negligible but radial differences were substantial. These results combine with past research to validate the non-woody cycad stem contains copious nonstructural resources available for deployment to ephemeral sinks during critical times of need.
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Affiliation(s)
- Thomas E Marler
- College of Natural and Applied Sciences, University of Guam, UOG Station, Mangilao, GU 96923, USA.
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Abstract
Conservation agencies charged with care of threatened plant species should be governed by the concepts that conservation actions should do no harm. Adaptive management research progresses in imperfect situations due to incomplete knowledge. Interpreting new experimental or observational evidence for inclusion in conservation plans should first consider the big picture by identifying collateral quandaries before scaling up the approach to large-scale implementation. We discuss a case study of Cycas micronesica conservation activities on the island of Guam. The use of large stem cuttings has been shown to be a viable approach for rescuing trees from planned construction sites. However, this artificial means of producing transplants exhibits shortcomings, some of which may add new threats to the existing plant population. Moreover, devoting funds for use of the new technique in tree rescue projects does not address the primary threats that have led to listing under the United States Endangered Species Act (ESA). Transplanted trees will likely succumb to those ubiquitous threats shortly after the completion of a successful rescue project. Alternatively, investing conservation funds into mitigation of the primary threats could lead to removal of the species from the ESA.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam, USA
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Marler TE, Lindström AJ, Marler PN. Diversity in Cycas (Cycadales: Cycadaceae) Species Offered as Larval Food Influences Fecundity of Chilades pandava (Lepidoptera: Lycaenidae) Adults. Int J Insect Sci 2017; 9:1179543317745863. [PMID: 29238238 PMCID: PMC5721961 DOI: 10.1177/1179543317745863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Chilades pandava (Lepidoptera: Lycaenidae) larval food quality was studied to determine its influence on adult life history traits. A wild population from Cycas nongnoochiae (Cycadales: Cycadaceae) endemic habitat behaved similarly to the population collected from a garden setting. Cycas micronesica, Cycas revoluta, and Cycas seemannii leaves were used as high-quality food, whereas C nongnoochiae, Cycas taitungensis, and Cycas condaoensis leaves were used as low-quality food. The daily oviposition rate was not influenced by food quality, but longevity and lifetime fecundity of females were increased by high-quality larval food. These results indicate that in situ Cycas species impose a physiological constraint on the genetic capacity to produce offspring by C pandava. The removal of that constraint by high-quality novel Cycas species may be one reason this butterfly can increase in population rapidly after an invasion event and express greater herbivory of Cycas species within invaded regions.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam, USA
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Abstract
Contemporary reviews of leaf responses to sunflecks indicate gymnosperms exhibit slower photosynthetic inductions times than angiosperms, but the gymnosperms were represented exclusively by conifers. I recently reported that the gymnosperm Cycas micronesica exhibited photosynthetic induction times in conformity with some of the most rapid angiosperms and opined that representatives from non-conifer gymnosperms must be added to the published conifer database before gymnosperm-wide conclusions can be formulated. Guiding principles for this urgently needed research will maximize relevance and improve accuracy of conclusions.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam, USA
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Marler TE. Diel root extension patterns of three Serianthes species are modulated by plant size. Plant Signal Behav 2017; 12:e1327496. [PMID: 28532228 PMCID: PMC5566354 DOI: 10.1080/15592324.2017.1327496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 04/29/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Diel root extension was observed for Serianthes grandiflora, Serianthes kanehirae, and Serianthes nelsonii plants ranging in size from seedlings to 2-m tall saplings. The percentage of daily root extension that occurred at night declined from 65% for seedlings to 51% for 200-cm tall plants for S. grandiflora, from 58% for seedlings to 54% for 200-cm tall plants for S. kanehirae, and from 72% for seedlings to 55% for 200-cm tall plants for S. nelsonii. These results indicate the timing of root extension rates throughout a diel cycle may be included in the list of phenology and physiology traits that change as plants increase in size.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, Mangilao, Guam
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Marler TE, Dongol N. Three invasive insects alter Cycas micronesica leaf chemistry and predict changes in biogeochemical cycling. Commun Integr Biol 2016; 9:e1208324. [PMID: 27829976 PMCID: PMC5100656 DOI: 10.1080/19420889.2016.1208324] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 06/23/2016] [Accepted: 06/24/2016] [Indexed: 11/05/2022] Open
Abstract
Leaf litter chemical traits were measured for Cycas micronesica plants in Guam following leaf herbivory by the scale Aulacaspis yasumatsui, the butterfly Chilades pandava caterpillar, or the leaf miner Erechthias sp. to determine the influence of the non-native pests on litter quality. Scale herbivory increased litter phenols above those of undamaged leaves but did not influence lignin or cellulose concentrations. Butterfly caterpillar herbivory increased litter phenols above and decreased litter lignin below those of undamaged leaves, but did not influence cellulose concentrations. Leaf miner herbivory increased litter lignin concentrations above those of undamaged leaves, but did not influence phenols or cellulose concentrations. Herbivory influenced 8 of 12 essential elements that were quantified. Herbivory by all 3 insects increased nitrogen and potassium litter concentrations and decreased calcium and iron litter concentrations when compared with undamaged litter. The responses were idiosyncratic among herbivores for the remaining essential elements. Stoichiometry among the chemical constituents indicated that herbivory increased litter quality and predicted more rapid biogeochemical cycling in Guam's ecosystems as a result of these 3 non-native insect invasions.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, UOG Station , Mangilao, Guam, USA
| | - Nirmala Dongol
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of Guam, UOG Station , Mangilao, Guam, USA
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Marler TE, Dongol N, Cruz GN. Leucaena leucocephala and adjacent native limestone forest habitats contrast in soil properties on Tinian Island. Commun Integr Biol 2016; 9:e1212792. [PMID: 27829978 PMCID: PMC5100652 DOI: 10.1080/19420889.2016.1212792] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 11/22/2022] Open
Abstract
An ex situ germplasm collection of the endangered Cycas micronesica was established in a transition zone between biodiverse native forest and mature stands of the invasive species Leucaena leucocephala. Soil chemical properties were determined for the 2 tree cover types to inform management decisions. Total carbon, total nitrogen, calcium, and net ammonification were greater in native forest cover than in L. leucocephala patches. Net nitrification and net mineralization were greater under L. leucocephala cover. Trace metals also differed between the 2 forest cover types, with chromium, cobalt, and nickel accumulating to greater concentration under L. leucocephala cover and zinc accumulating to greater concentration under native forest cover. The results indicated that L. leucocephala cover generated substantial changes in soil chemical properties when compared with native forest tree cover, illuminating one means by which understory vegetation may be affected by changes in invasive tree cover.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station , Mangilao, Guam, USA
| | - Nirmala Dongol
- Western Pacific Tropical Research Center, University of Guam, UOG Station , Mangilao, Guam, USA
| | - Gil N Cruz
- Western Pacific Tropical Research Center, University of Guam, UOG Station , Mangilao, Guam, USA
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Marler TE, Lindström AJ, Marler PN. Chilades pandava mothers discriminate among Cycas species during oviposition choice tests, but only in an endemic naïve population. Plant Signal Behav 2016; 11:e1208879. [PMID: 27391307 PMCID: PMC5022404 DOI: 10.1080/15592324.2016.1208879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 06/28/2016] [Accepted: 06/29/2016] [Indexed: 06/06/2023]
Abstract
Host and non-host plant species communicate with insect herbivores to influence oviposition decisions. We studied if Chilades pandava female adults expressed oviposition preferences among host Cycas species in 2 choice tests, counting 39,420 eggs among assays from 4 butterfly populations. A naïve butterfly population from Cycas nongnoochiae habitat oviposited 2.2-fold more eggs on leaves of Cycas species that are susceptible to butterfly herbivory than on leaves of its native host Cycas nongnoochiae. In contrast, Chilades pandava populations experienced with novel Cycas species in Thailand, Philippines, and Guam exhibited no preference in choice tests between leaves of susceptible versus leaves of minimally damaged Cycas species. The results indicated that oviposition deterrents and/or stimulants partly mediate the sustainable relationship between an endemic Cycas species and the naïve Chilades pandava population from its habitat. Alternatively, differences in infochemicals among Cycas species do not enable discrimination in oviposition choices for Chilades pandava populations that have experienced Cycas species exhibiting no evolutionary history with Chilades pandava.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam, USA
| | - Anders J. Lindström
- Nong Nooch Tropical Botanical Garden, Najomtien, Sattahip, Chonburi, Thailand
| | - Paris N. Marler
- Centre for Sustainability, Barangay Sta. Lucia, Puerto Princesa City, Palawan, Philippines
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Abstract
Trends in published cycad research within various fields of study were determined using proceedings from international conferences on cycad biology and Google Scholar to access the primary literature. Both search methods indicated that phylogeny, systematics and ecology are strongly represented in recent cycad literature, while there is a need for more research in horticulture and pathology, reviews and clarification of correspondence between current and discontinued species designations.
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Marler TE, Cascasan AN. Number of emerged seedlings and seedling longevity of the non-recruiting, Critically Endangered Håyun lågu Tree Serianthes nelsonii Merr. (Fabales: Leguminosae) are influenced by month of emergence. J Threat Taxa 2015. [DOI: 10.11609/jott.2100.7.15.8221-8225] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
<p>Emergence and longevity of seedlings beneath Guam’s only known Håyun lågu Tree <em>Serianthes nelsonii</em> were studied to determine the fate of every observed seedling during 2013. Newly emerged seedlings were marked with wire stakes every 15 days, then the stakes were collected at each seedling upon death. Longevity of each seedling was calculated from the marked ending and emergence dates. The least number of newly emerged seedlings was recorded at the end of the dry season, and the greatest number of newly emerged seedlings was recorded in the beginning of the rainy season. More than half of the year’s 374 seedlings died in less than 30 days. Seedling longevity ranged from a mean of 31 days for seedlings that emerged in May to 78 days for seedlings that emerged in June. Our results reveal that the baseline level of recruitment potential of the lone survivor of this species on Guam is substantial, and underscore the need for further research to determine the factors associated with the acutely limited seedling lifespan.</p><div> </div>
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Abstract
Contributions of biologists to tropical cyclone research may improve by integrating concepts from other disciplines. Employing accumulated cyclone energy into protocols may foster greater integration of ecology and meteorology research. Considering experienced ecosystems as antifragile instead of just resilient may improve cross-referencing among ecological and social scientists. Quantifying ecosystem capital as distinct from ecosystem services may improve integration of tropical cyclone ecology research into the expansive global climate change research community.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station ; Mangilao, Guam USA
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Abstract
Cycad biology, ecology, and horticulture decisions are not supported by adequate research, and experiments in cycad physiology in particular have been deficient. Our recent report on free sugar content in a range of cycad taxa and tissues sets the stage for developing continued carbohydrate research. Growth and development of cycad pollen, mediation of the herbivory traits of specialist pollinators, and support of expensive strobilus behavioral traits are areas of cycad pollination biology that would benefit from a greater understanding of the role of carbohydrate relations.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station ; Mangilao, Guam USA
| | - Anders J Lindström
- Nong Nooch Tropical Botanical Garden ; Najomtien ; Sattahip, Chonburi, Thailand
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Marler TE, Lindström AJ. The value of research to selling the conservation of threatened species: the case of Cycas micronesica (Cycadopsida: Cycadales: Cycadaceae). J Threat Taxa 2014. [DOI: 10.11609/jott.o4098.6523-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Abstract
The sugars fructose, glucose, maltose, and sucrose were quantified in seven tissues of Zamia muricata Willd. to determine their distribution throughout various organs of a model cycad species, and in lateral structural roots of 18 cycad species to determine the variation in sugar concentration and composition among species representing every cycad genus. Taproot and lateral structural roots contained more sugars than leaf, stem, female strobilus, or coralloid roots. For example, taproot sugar concentration was 6.4-fold greater than stem sugar concentration. The dominant root sugars were glucose and fructose, and the only detected stem sugar was sucrose. Sucrose also dominated the sugar profile for leaflet and coralloid root tissue, and fructose was the dominant sugar in female strobilus tissue. Maltose was a minor constituent of taproot, leaflet, and female strobilus tissue, but absent in other tissues. The concentration of total free sugars and each of the four sugars did not differ among genera or families. Stoichiometric relationships among the sugars, such as the quotient hexoses/disaccharides, differed among organs and families. Although anecdotal reports on cycad starch have been abundant due to its historical use as human food and the voluminous medical research invested into cycad neurotoxins, this is the first report on the sugar component of the non-structural carbohydrate profile of cycads. Fructose, glucose, and sucrose are abundant in cycad tissues, with their relative abundance highly contrasting among organs. Their importance as forms of carbon storage, messengers of information, or regulators of cycad metabolism have not been determined to date.
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Affiliation(s)
- Thomas E. Marler
- Western Pacific Tropical Research Center, College of Natural and Applied Sciences, University of GuamMangilao, Guam
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Marler TE, Ferreras U. Differential leaflet mortality may influence biogeochemical cycling following tropical cyclones. Commun Integr Biol 2014; 7:e27924. [PMID: 25083171 PMCID: PMC4094194 DOI: 10.4161/cib.27924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
Intensity of tropical cyclones is expected to increase in the coming century, and an improved understanding of their influence on biogeochemical cycles would benefit ecologists and conservationists. We studied the November 2013 Typhoon Haiyan damage to observe that numerous examples of partial leaf necrosis on intact leaves of trees in the Cycadaceae and Arecaceae families resulted, leaving behind a copious amount of arboreal dead leaf material attached to live leaves. The decay process of this form of arboreal litter has not been previously studied. When compared with decay of ground litter or detached litter suspended in the canopy, we predict the decay process of this form of arboreal litter will include increased photooxidation, leaching, and comminution by detritivorous insects and mites; but decreased catabolism of organic molecules by saprophytic organisms.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
| | - Ulysses Ferreras
- Philippine Native Plants Conservation Society Inc.; Ninoy Aquino Parks and Wildlife Center; Quezon City, Philippines
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Watson G, Marler TE. Does cycad aulacaspis scale (Aulacaspis yasumatsui, Hemiptera: Diaspididae) play a direct role in causing soil phytotoxicity? Commun Integr Biol 2014; 7:e27881. [PMID: 25083170 PMCID: PMC4094193 DOI: 10.4161/cib.27881] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 01/16/2014] [Indexed: 12/05/2022] Open
Abstract
Cycad aulacaspis scale (CAS, Aulacaspis yasumatsui, Hemiptera: Diaspididae) was accidentally introduced to Guam in 2003, and has caused acute mortality of the dominant, endemic forest tree Cycas micronesica. A phytotoxic legacy in the soils beneath cycad trees killed by CAS over a period of about three years has been demonstrated. The origin of the toxicity may be large quantities of CAS-encrusted cycad leaf litter. We explore the possibility that a major contribution to this toxic legacy may come from the scale insects, not just from the plant material.
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Affiliation(s)
- Gillian Watson
- California Department of Food and Agriculture; Plant Pest Diagnostic Center; Sacramento; CA USA
| | - Thomas E Marler
- College of Natural and Applied Sciences; University of Guam; UOG Station; Mangilao; Guam USA
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Gorelick R, Marler TE. Kin recognition by roots occurs in cycads and probably in conifers. Commun Integr Biol 2014; 7:e28009. [PMID: 24778761 PMCID: PMC3995734 DOI: 10.4161/cib.28009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 01/26/2014] [Accepted: 01/27/2014] [Indexed: 01/09/2023] Open
Abstract
Kin recognition by the roots of Cycas edentata was recently demonstrated. Our extensive literature search revealed this to be the first report of kin recognition in any spermatophyte other than angiosperms. Based on this new validation that the phenomenon occurs among phylogenetically diverse taxa, we conclude that kin recognition by roots may be an ancient phenomenon.
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Marler TE. The intersection of a military culture and indigenous peoples in conservation issues. Commun Integr Biol 2013; 6:e26665. [PMID: 24567778 PMCID: PMC3925457 DOI: 10.4161/cib.26665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 10/01/2013] [Indexed: 11/19/2022] Open
Abstract
Military operations impose various positive and negative consequences on the environment. Three case studies are presented illuminating how local indigenous peoples as stakeholders may be vulnerable to being disenfranchised from important discussions concerning military activities. The study of ecological issues associated with sustaining a military footprint may be particularly useful for informing the global debate that pits strict conservation against human well-being.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam
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Roemer RB, Terry LI, Marler TE. Cone thermogenesis and its limits in the tropical Cycas micronesica (Cycadaceae): association with cone growth, dehiscence, and post-dehiscence phases. Am J Bot 2013; 100:1981-1990. [PMID: 24081147 DOI: 10.3732/ajb.1300047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
PREMISE OF THE STUDY Thermogenesis is a prominent pollination-related feature of cycad cones and is generally assumed to play a role in pollination. Although typically studied just before, during, and immediately after the cones' pollination phase, thermogenesis may be present in other cone developmental phases. • METHODS We assayed thermogenesis in Cycas micronesica, Guam's endangered cycad, over successive cone developmental phases by measuring temperatures in shaded and unshaded in situ cones for up to 7 wk. We also studied the effect of ambient conditions on cone thermogenesis in laboratory experiments and estimated the cones' metabolic heating rates. • KEY RESULTS Pollen cones exhibit a continuous, but small, metabolically generated thermogenesis for multiple weeks, including a single thermogenic peak temperature greater than peak ambient each day. The magnitudes of those daily peak temperature elevations above ambient reach maxima twice during cone development: a few days before dehiscence and approximately 1 wk post-dehiscence. Excised cones in dark, fixed temperature environments generated multiple thermogenic events (∼24 h period) over ∼10 d. Cones appear to initiate a protective temperature regulatory response at temperatures ≥∼38°C. • CONCLUSIONS Cycas micronesica pollen cones exhibit several thermogenic attributes not reported in other cycads, including continuous thermogenesis for many weeks. These cones grow in a hot tropical environment that likely confines their metabolically generated temperature increases to a small thermogenic window beyond which they encounter heat stress. These findings suggest the presence of thermogenic functions not strictly related to pollination and a potential vulnerability to warming climates.
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Affiliation(s)
- Robert B Roemer
- University of Utah, Department of Mechanical Engineering, 50 S. Central Campus Dr., Salt Lake City, Utah, 84112 USA
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Abstract
Concerns about aluminum (Al) exposure in the human diet have persisted for one century. We suggest that continued research would benefit from better reporting of environmental factors that are known to influence Al accumulation in plant organs that are consumed, focusing on subsets of the general public that exhibit the highest risk for neuropathological responses, increased evaluation of commercial processing procedures that may concentrate Al or other toxic substances, and designing studies with low dose, chronic exposure rather than further study of acute, brief exposure.
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Affiliation(s)
- Christopher A Shaw
- University of British Columbia, Departments of Ophthalmology and Medical Science, Experimental Medicine, and Graduate Program in Neuroscience; Vancouver, BC Canada
| | - Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
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Marler TE, Del Moral R. Primary succession in Mount Pinatubo: Habitat availability and ordination analysis. Commun Integr Biol 2013; 6:e25924. [PMID: 24505499 PMCID: PMC3913662 DOI: 10.4161/cib.25924] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 07/27/2013] [Indexed: 11/19/2022] Open
Abstract
Vegetation structure on the east flank of Mount Pinatubo was investigated to determine the inventory of species at 15 y post-eruption, then to ascertain environmental variables that have influenced the early patterns of primary succession. Unconstrained and constrained ordination methods were used to determine the influence of spatial, elevation, and substrate patterns on vegetation. Vegetation was assigned to one of 3 habitat types. Scours were eroded flat surfaces, terraces were perched flat surfaces, and talus piles were created along the canyon edges as mass waste events. The influence of habitat type on vegetation was multifaceted because they represent different conditions and different histories. The talus piles have preferential access to colonists from the vegetation on the canyon walls above and a more benign microclimate than the exposed terrace and scour sites. Scoured sites on the valley floor exhibited the least vegetation cover, as these substrates had the least mature surfaces and the most restricted capacity for root exploration. Perched terraces exhibited greater plant dominance than did the other habitats in the early stages of succession because of the ubiquitous appearance of Parasponia rugosa as initial colonists on these relatively flat surfaces. Polynomial canonical correspondence analysis was more closely aligned with the pattern of vegetation than linear canonical correspondence analysis, and therefore more closely approximated accurate descriptions of correlations among site ordination positions and measured variables. These results confirm that a variety of statistical approaches can clarify applications for restoration ecology following landslide and volcanic disturbances or agriculture and forestry anthropogenic disturbances in the lowland tropics.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
| | - Roger Del Moral
- Department of Biology; University of Washington; Seattle, WA USA
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Abstract
Spatial heterogeneity within individual host trees is often overlooked in surveys of phytophagous arthropod abundance and distribution. The armored scale Aulacaspis yasumatsui is controlled by the predator Rhyzobius lophanthae to a greater degree on leaves at 75-cm height than on leaves at ground level within its host tree Cycas micronesica. The direct influence of elevation on the predator indirectly generates vertical heterogeneity of the scale insect. Arthropod sampling schemes that fail to include all strata within the vertical profile of the host tree species may generate misleading outcomes. Results indicate that sub-meter increments can reveal significant differences in vertical distribution of phytophagous insects, and that inclusion of observations on other organisms that interact with the target arthropod may illuminate determinants of vertical heterogeneity.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
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Marler TE, Lawrence JH. Canopy and knowledge gaps when invasive alien insects remove foundation species. Commun Integr Biol 2013; 6:e22331. [PMID: 23847712 PMCID: PMC3689568 DOI: 10.4161/cib.22331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 09/22/2012] [Indexed: 12/15/2022] Open
Abstract
The armored scale Aulacaspis yasumatsui invaded the northern range of the cycad Cycas micronesica in 2003, and epidemic tree mortality ensued due to a lack of natural enemies of the insect. We quantified cycad demographic responses to the invasion, but the ecological responses to the selective removal of this foundation species have not been addressed. We use this case to highlight information gaps in our understanding of how alien invasive phytophagous insects force cascading adverse ecosystem changes. The mechanistic role of unique canopy gaps, oceanic island examples and threatened foundation species with distinctive traits are three issues that deserve research efforts in a quest to understand this facet of ecosystem change occurring across multiple settings globally.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
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Marler TE. Increased threat of island endemic tree's extirpation via invasion-induced decline of intrinsic resistance to recurring tropical cyclones. Commun Integr Biol 2013; 6:e22361. [PMID: 23802037 PMCID: PMC3689569 DOI: 10.4161/cib.22361] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 09/22/2012] [Accepted: 09/25/2012] [Indexed: 12/03/2022] Open
Abstract
Cycas micronesica populations in Guam have been threatened by the invasion of the armored scale Aulacaspis yasumatsui. I integrate four factors that illuminate an acute need for intervention to reduce an unprecedented threat caused by the invasion. First, mechanical failure of healthy C. micronesica trees during catastrophic winds is rare because of the cycad tree’s unique pachycaulis stem design. Second, tree-winching and three-point bend stress tests revealed the natural resistance to damage from tropical cyclones has been compromised by the chronic feeding of this homopteran pest. Third, no typhoon event has occurred since the arthropod’s invasion and its spread in the year 2005 to actually test extent of mechanical failure for the unhealthy remaining trees. Fourth, historical records indicate the probability that Guam will experience typhoon force winds is 0.51 in three years and 0.91 in 10 y. These four factors integrate to predict the next typhoon may eliminate the surviving C. micronesica trees and stewardship of this declining population requires intervention to counter this prediction.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center; University of Guam; UOG Station; Mangilao, Guam USA
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Abstract
Plant defensive behaviors that resist arthropod herbivory include trichome-mediated defenses, and variation in plant trichome morphology and abundance provides examples of the mechanistic complexities of insect-plant interactions. Trichomes were removed from Cycas revoluta cataphylls on the island of Guam to reveal Aulacaspis yasumatsui scale infestation, and predation of the newly exposed insects by pre-existing Rhyzobius lophanthae beetles commenced within one day. The quotient of predated/total scale insects was 0.5 by day 4 and stabilized at that found on adjacent glabrous leaves in about one week. The trichome phenotype covering the C. revoluta cataphyll complex offers the invasive A. yasumatsui armored scale effectual enemy-free space in this system. This pest and predator share no known evolutionary history with C. revoluta, therefore, the adaptive significance of this plant behavior in natural habitat is not yet known.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam.
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Abstract
Invasive arthropod herbivores comprise one of the greatest threats to cycad conservation both in situ and ex situ. We discuss two mechanisms, not necessarily mutually exclusive, that may underlie the disparity in Chilades pandava damage among Cycas species. In an information-based system, plant infochemicals may differentially influence oviposition behavior of Ch. pandava adults or host finding behavior of this butterfly's natural enemies. Alternatively, heterogeneity in damage may be mediated by a resource-based system whereby plant substrate is more palatable to larvae for susceptible species or more defended by less damaged species.
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Affiliation(s)
- Thomas E Marler
- Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam, USA.
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