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Iuorio A, Eppinga MB, Baudena M, Veerman F, Rietkerk M, Giannino F. Modelling how negative plant-soil feedbacks across life stages affect the spatial patterning of trees. Sci Rep 2023; 13:19128. [PMID: 37926717 PMCID: PMC10625994 DOI: 10.1038/s41598-023-44867-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 10/12/2023] [Indexed: 11/07/2023] Open
Abstract
In this work, we theoretically explore how litter decomposition processes and soil-borne pathogens contribute to negative plant-soil feedbacks, in particular in transient and stable spatial organisation of tropical forest trees and seedlings known as Janzen-Connell distributions. By considering soil-borne pathogens and autotoxicity both separately and in combination in a phenomenological model, we can study how both factors may affect transient dynamics and emerging Janzen-Connell distributions. We also identify parameter regimes associated with different long-term behaviours. Moreover, we compare how the strength of negative plant-soil feedbacks was mediated by tree germination and growth strategies, using a combination of analytical approaches and numerical simulations. Our interdisciplinary investigation, motivated by an ecological question, allows us to construct important links between local feedbacks, spatial self-organisation, and community assembly. Our model analyses contribute to understanding the drivers of biodiversity in tropical ecosystems, by disentangling the abilities of two potential mechanisms to generate Janzen-Connell distributions. Furthermore, our theoretical results may help guiding future field data analyses by identifying spatial signatures in adult tree and seedling distribution data that may reflect the presence of particular plant-soil feedback mechanisms.
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Affiliation(s)
- Annalisa Iuorio
- Department of Engineering, Centro Direzionale-Isola C4, Parthenope University of Naples, 80143, Naples, Italy.
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern-Platz 1, 1090, Vienna, Austria.
| | - Maarten B Eppinga
- Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Mara Baudena
- Environmental Sciences Group, Copernicus Institute of Sustainable Development, Utrecht University, 3508 TC, Utrecht, The Netherlands
- Institute of Atmospheric Sciences and Climate (CNR-ISAC), National Research Council of Italy, Corso Fiume 4, 10133, Torino, Italy
| | - Frits Veerman
- Mathematical Institute, Leiden University, Niels Bohrweg 1, 2300 RA, Leiden, The Netherlands
| | - Max Rietkerk
- Environmental Sciences Group, Copernicus Institute of Sustainable Development, Utrecht University, 3508 TC, Utrecht, The Netherlands
| | - Francesco Giannino
- Department of Agricultural Sciences, University of Naples Federico II, via Università 100, 80055, Portici, Italy
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2
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Xu C, Silliman BR, Chen J, Li X, Thomsen MS, Zhang Q, Lee J, Lefcheck JS, Daleo P, Hughes BB, Jones HP, Wang R, Wang S, Smith CS, Xi X, Altieri AH, van de Koppel J, Palmer TM, Liu L, Wu J, Li B, He Q. Herbivory limits success of vegetation restoration globally. Science 2023; 382:589-594. [PMID: 37917679 DOI: 10.1126/science.add2814] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/21/2023] [Indexed: 11/04/2023]
Abstract
Restoring vegetation in degraded ecosystems is an increasingly common practice for promoting biodiversity and ecological function, but successful implementation is hampered by an incomplete understanding of the processes that limit restoration success. By synthesizing terrestrial and aquatic studies globally (2594 experimental tests from 610 articles), we reveal substantial herbivore control of vegetation under restoration. Herbivores at restoration sites reduced vegetation abundance more strongly (by 89%, on average) than those at relatively undegraded sites and suppressed, rather than fostered, plant diversity. These effects were particularly pronounced in regions with higher temperatures and lower precipitation. Excluding targeted herbivores temporarily or introducing their predators improved restoration by magnitudes similar to or greater than those achieved by managing plant competition or facilitation. Thus, managing herbivory is a promising strategy for enhancing vegetation restoration efforts.
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Affiliation(s)
- Changlin Xu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Brian R Silliman
- Nicholas School of the Environment, Duke University, Beaufort, NC, USA
| | - Jianshe Chen
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Xincheng Li
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Mads S Thomsen
- Marine Ecology Research Group and Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Qun Zhang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Juhyung Lee
- Marine Science Center, Northeastern University, Nahant, MA, USA
- Department of Oceanography and Marine Research Institute, Pusan National University, Busan, Republic of Korea
| | - Jonathan S Lefcheck
- Tennenbaum Marine Observatories Network and MarineGEO Program, Smithsonian Environmental Research Center, Edgewater, MD, USA
- University of Maryland Center for Environmental Science, Cambridge, MD, USA
| | - Pedro Daleo
- Instituto de Investigaciones Marinas y Costeras (IIMyC), UNMdP, CONICETC, Mar del Plata, Argentina
| | - Brent B Hughes
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Holly P Jones
- Department of Biological Sciences and Institute for the Study of the Environment, Sustainability, and Energy, Northern Illinois University, DeKalb, IL, USA
| | - Rong Wang
- School of Ecological and Environmental Sciences, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, East China Normal University, Shanghai, China
| | - Shaopeng Wang
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Carter S Smith
- Nicholas School of the Environment, Duke University, Beaufort, NC, USA
| | - Xinqiang Xi
- Department of Ecology, School of Life Science, Nanjing University, Nanjing, Jiangsu, China
| | - Andrew H Altieri
- Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, USA
| | - Johan van de Koppel
- Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Yerseke, Netherlands
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Todd M Palmer
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Jihua Wu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, and College of Ecology, Lanzhou University, Lanzhou, Gansu, China
| | - Bo Li
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Qiang He
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
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3
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Lebrija-Trejos E, Hernández A, Wright SJ. Effects of moisture and density-dependent interactions on tropical tree diversity. Nature 2023; 615:100-104. [PMID: 36792827 DOI: 10.1038/s41586-023-05717-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/08/2023] [Indexed: 02/17/2023]
Abstract
Tropical tree diversity increases with rainfall1,2. Direct physiological effects of moisture availability and indirect effects mediated by biotic interactions are hypothesized to contribute to this pantropical increase in diversity with rainfall2-6. Previous studies have demonstrated direct physiological effects of variation in moisture availability on tree survival and diversity5,7-10, but the indirect effects of variation in moisture availability on diversity mediated by biotic interactions have not been shown11. Here we evaluate the relationships between interannual variation in moisture availability, the strength of density-dependent interactions, and seedling diversity in central Panama. Diversity increased with soil moisture over the first year of life across 20 annual cohorts. These first-year changes in diversity persisted for at least 15 years. Differential survival of moisture-sensitive species did not contribute to the observed changes in diversity. Rather, negative density-dependent interactions among conspecifics were stronger and increased diversity in wetter years. This suggests that moisture availability enhances diversity indirectly through moisture-sensitive, density-dependent conspecific interactions. Pathogens and phytophagous insects mediate interactions among seedlings in tropical forests12-18, and many of these plant enemies are themselves moisture-sensitive19-27. Changes in moisture availability caused by climate change and habitat degradation may alter these interactions and tropical tree diversity.
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Affiliation(s)
- Edwin Lebrija-Trejos
- Department of Biology and Environment, University of Haifa-Oranim, Kiryat Tiv'on, Israel.
| | | | - S Joseph Wright
- Smithsonian Tropical Research Institute, Balboa Ancón, Panama
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4
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Teste FP, Laliberté E. A test of the Janzen‐Connell hypothesis in a species‐rich Mediterranean woodland. Ecosphere 2021. [DOI: 10.1002/ecs2.3821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- François P. Teste
- Grupo de Estudios Ambientales IMASL‐CONICET & Universidad Nacional de San Luis Av. Ejercito de los Andes 950 (5700) San Luis Argentina
- School of Biological Sciences The University of Western Australia Crawley Western Australia 6009 Australia
| | - Etienne Laliberté
- School of Biological Sciences The University of Western Australia Crawley Western Australia 6009 Australia
- Département de sciences biologiques Institut de recherche en biologie végétale Centre sur la biodiversité Université de Montréal 4101 Sherbrooke Est Montreal Qubec H1X 2B2 Canada
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5
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Song X, Corlett RT. Do natural enemies mediate conspecific negative distance‐ and density‐dependence of trees? A meta‐analysis of exclusion experiments. OIKOS 2021. [DOI: 10.1111/oik.08509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaoyang Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences Mengla China
| | - Richard T. Corlett
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences Mengla China
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China
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6
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Song X, Corlett RT. Enemies mediate distance- and density-dependent mortality of tree seeds and seedlings: a meta-analysis of fungicide, insecticide and exclosure studies. Proc Biol Sci 2021; 288:20202352. [PMID: 33468003 DOI: 10.1098/rspb.2020.2352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Conspecific negative distance- and density-dependence is often assumed to be one of the most important mechanisms controlling forest community assembly and species diversity globally. Plant pathogens, and insect and mammalian herbivores, are the most common natural enemy types that have been implicated in this phenomenon, but their general effects at different plant life stages are still unclear. Here, we conduct a meta-analysis of studies that involved robust manipulative experiments, using fungicides, insecticides and exclosures, to assess the contributions of different natural enemy types to distance- and density-dependent effects at seed and seedling stages. We found that distance- and density-dependent mortality caused by natural enemies was most likely at the seedling stage and was greater at higher mean annual temperatures. Conspecific negative distance- and density-dependence at the seedling stage is significantly weakened when fungicides were applied. By contrast, negative conspecific distance- and density-dependence is not a general pattern at the seed stage. High seed mass reduced distance- and density-dependent mortality at the seed stage. Seed studies excluding only large mammals found significant negative conspecific distance-dependent mortality, but exclusion of all mammals resulted in a non-significant effect of conspecifics. Our study suggests that plant pathogens are a major cause of distance- and density-dependent mortality at the seedling stage, while the impacts of herbivores on seedlings have been understudied. At the seed stage, large and small mammals, respectively, weaken and enhance negative conspecific distance-dependent mortality. Future research should identify specific agents of mortality, investigate the interactions among different enemy types and assess how global change may affect natural enemies and thus influence the strength of conspecific distance- and density-dependence.
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Affiliation(s)
- Xiaoyang Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, People's Republic of China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, People's Republic of China
| | - Richard T Corlett
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, People's Republic of China.,Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, People's Republic of China
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7
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Song X, Lim JY, Yang J, Luskin MS. When do Janzen-Connell effects matter? A phylogenetic meta-analysis of conspecific negative distance and density dependence experiments. Ecol Lett 2020; 24:608-620. [PMID: 33382527 DOI: 10.1111/ele.13665] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 08/18/2020] [Accepted: 11/25/2020] [Indexed: 12/24/2022]
Abstract
The Janzen-Connell (J-C) hypothesis suggests that specialised natural enemies cause distance- or density-dependent mortality among host plants and is regarded as an important mechanism for species coexistence. However, there remains debate about whether this phenomenon is widespread and how variation is structured across taxa and life stages. We performed the largest meta-analysis of experimental studies conducted under natural settings to date. We found little evidence of distance-dependent or density-dependent mortality when grouping all types of manipulations. Our analysis also reveals very large variation in response among species, with 38.5% of species even showing positive responses to manipulations. However, we found a strong signal of distance-dependent mortality among seedlings but not seed experiments, which we attribute to (a) seedlings sharing susceptible tissues with adults (leaves, wood, roots), (b) seedling enemies having worse dispersal than seed enemies and (c) seedlings having fewer physical and chemical defences than seeds. Both density- and distance-dependent mortality showed large variation within genera and families, suggesting that J-C effects are not strongly phylogenetically conserved. There were no clear trends with latitude, rainfall or study duration. We conclude that J-C effects may not be as pervasive as widely thought. Understanding the variation in J-C effects provides opportunities for new discoveries that will refine our understanding of J-C effects and its role in species coexistence.
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Affiliation(s)
- Xiaoyang Song
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, 666303, China.,Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China
| | - Jun Ying Lim
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jie Yang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, 666303, China.,Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China
| | - Matthew Scott Luskin
- School of Biological Sciences, University of Queensland, Brisbane, Qld., 4072, Australia
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8
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Cannon PG, O’Brien MJ, Yusah KM, Edwards DP, Freckleton RP. Limited contributions of plant pathogens to density-dependent seedling mortality of mast fruiting Bornean trees. Ecol Evol 2020; 10:13154-13164. [PMID: 33304525 PMCID: PMC7713929 DOI: 10.1002/ece3.6906] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 09/16/2020] [Indexed: 11/07/2022] Open
Abstract
Fungal pathogens are implicated in driving tropical plant diversity by facilitating strong, negative density-dependent mortality of conspecific seedlings (C-NDD). Assessment of the role of fungal pathogens in mediating coexistence derives from relatively few tree species and predominantly the Neotropics, limiting our understanding of their role in maintaining hyper-diversity in many tropical forests. A key question is whether fungal pathogen-mediated C-NDD seedling mortality is ubiquitous across diverse plant communities. Using a manipulative shadehouse experiment, we tested the role of fungal pathogens in mediating C-NDD seedling mortality of eight mast fruiting Bornean trees, typical of the species-rich forests of South East Asia. We demonstrate species-specific responses of seedlings to fungicide and density treatments, generating weak negative density-dependent mortality. Overall seedling mortality was low and likely insufficient to promote overall community diversity. Although conducted in the same way as previous studies, we find little evidence that fungal pathogens play a substantial role in determining patterns of seedling mortality in a SE Asian mast fruiting forest, questioning our understanding of how Janzen-Connell mechanisms structure the plant communities of this globally important forest type.
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Affiliation(s)
- Patrick G. Cannon
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldUK
| | - Michael J. O’Brien
- Área de Biodiversidad y ConservaciónUniversidad Rey Juan CarlosMóstolesSpain
- Danum Valley Field CentreSouth East Asian Rainforest Research Partnership (SEARRP)Lahad DatuSabahMalaysia
| | - Kalsum M. Yusah
- Institute for Tropical Biology and ConservationUniversiti Malaysia SabahKota KinabaluSabahMalaysia
| | - David P. Edwards
- Department of Animal and Plant SciencesThe University of SheffieldSheffieldUK
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9
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Krishnadas M, Agarwal K, Comita LS. Edge effects alter the role of fungi and insects in mediating functional composition and diversity of seedling recruits in a fragmented tropical forest. ANNALS OF BOTANY 2020; 126:1181-1191. [PMID: 32710752 PMCID: PMC7684699 DOI: 10.1093/aob/mcaa138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND AIMS In fragmented forests, proximity to forest edges can favour the establishment of resource-acquisitive species over more resource-conservative species. During seedling recruitment, resource-acquisitive species may benefit from either higher light availability or weaker top-down effects of natural enemies. The relative importance of light and enemies for recruitment has seldom been examined with respect to edge effects. METHODS In a human-modified wet tropical forest in India, we first examined how functional traits indicative of resource-acquisitive vs. resource-conservative strategies, i.e. specific leaf area (SLA), leaf dry matter content, wood density and seed size, explained interspecific differences in densities of seedling recruits with distance to the forest edge. Then, we checked whether fungicide and insecticide treatments and canopy openness (proxy for light availability) explained edge effects on trait-mediated changes in seedling density. Finally, we examined whether light availability and natural enemy activity explained edge effects on functional diversity of seedling recruits. KEY RESULTS Up to 60 m from edges, recruit densities increased with decreasing seed size, but not at 90-100 m, where recruit densities increased with higher SLA. Trait-mediated variation in recruit densities changed with pesticides only at 90-100 m: compared with control plots, fungicide increased recruit densities for low SLA species and insecticide increased smaller seeded species. For SLA, wood density and seed size, functional diversity of recruits was higher at 90-100 m than at 0-5 m. At 90-100 m, fungicide decreased functional diversity for SLA and insecticide reduced seed size diversity compared with control plots. Canopy openness explained neither variation in recruit density in relation to traits nor functional diversity. CONCLUSIONS Altered biotic interactions can mediate local changes to trait composition and functional diversity during seedling recruitment in forest fragments, hinting at downstream effects on the structure and function of human-modified forests.
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Affiliation(s)
- Meghna Krishnadas
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
- Centre for Cellular and Molecular Biology, Habshiguda, Hyderabad, Telangana, India
| | - Kavya Agarwal
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
| | - Liza S Comita
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
- Smithsonian Tropical Research Institute, Balboa, Ancón, Panama
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10
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Urrea-Galeano LA, Andresen E, Coates R, Mora Ardila F, Díaz Rojas A, Ramos-Fernández G. Horizontal seed dispersal by dung beetles reduced seed and seedling clumping, but did not increase short-term seedling establishment. PLoS One 2019; 14:e0224366. [PMID: 31648268 PMCID: PMC6812793 DOI: 10.1371/journal.pone.0224366] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 10/11/2019] [Indexed: 11/18/2022] Open
Abstract
Dung beetles are secondary seed dispersers, incidentally moving many of the seeds defecated by mammals vertically (seed burial) and/or horizontally as they process and relocate dung. Although several studies have quantified this ecological function of dung beetles, very few have followed seed fate until seedling establishment, and most of these have focused on the effects of seed burial. We know very little about the effects of horizontal seed movement by dung beetles, though it is generally assumed that it will affect plant recruitment positively through diminishing seed clumping. The objective of our study was to assess the effects of dung beetle activity on the spatial distribution of seeds and seedlings, and on the probability of seedling establishment. In a tropical rainforest in Mexico we carried out two complementary field experiments for each of two tree species (Bursera simaruba and Poulsenia armata), using seeds experimentally imbedded in pig dung and recording their fate and spatial location over time. For both species, dung beetle activity reduced the spatial clumping of seeds and seedlings; however, it did not increase the probability of seedling establishment. We discuss the context- and species-specificity of the combined effects of horizontal and vertical dispersal of seeds by dung beetles, and the need to quantify long-term seedling fates to more accurately determine the effects of seed movement by dung beetles on plant recruitment.
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Affiliation(s)
- Lina Adonay Urrea-Galeano
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, Mexico
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- * E-mail: (EA); (LAUG)
| | - Ellen Andresen
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, Mexico
- * E-mail: (EA); (LAUG)
| | - Rosamond Coates
- Estación de Biología Tropical Los Tuxtlas, Instituto de Biología, Universidad Nacional Autónoma de México, Veracruz, Mexico
| | - Francisco Mora Ardila
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, Mexico
| | | | - Gabriel Ramos-Fernández
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
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11
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Detto M, Visser MD, Wright SJ, Pacala SW. Bias in the detection of negative density dependence in plant communities. Ecol Lett 2019; 22:1923-1939. [PMID: 31523913 DOI: 10.1111/ele.13372] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/20/2019] [Accepted: 07/19/2019] [Indexed: 01/22/2023]
Abstract
Regression dilution is a statistical inference bias that causes underestimation of the strength of dependency between two variables when the predictors are error-prone proxies (EPPs). EPPs are widely used in plant community studies focused on negative density-dependence (NDD) to quantify competitive interactions. Because of the nature of the bias, conspecific NDD is often overestimated in recruitment analyses, and in some cases, can be erroneously detected when absent. In contrast, for survival analyses, EPPs typically cause NDD to be underestimated, but underestimation is more severe for abundant species and for heterospecific effects, thereby generating spurious negative relationships between the strength of NDD and the abundances of con- and heterospecifics. This can explain why many studies observed rare species to suffer more severely from conspecific NDD, and heterospecific effects to be disproportionally smaller than conspecific effects. In general, such species-dependent bias is often related to traits associated with likely mechanisms of NDD, which creates false patterns and complicates the ecological interpretation of the analyses. Classic examples taken from literature and simulations demonstrate that this bias has been pervasive, which calls into question the emerging paradigm that intraspecific competition has been demonstrated by direct field measurements to be generally stronger than interspecific competition.
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Affiliation(s)
- Matteo Detto
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Smithsonian Tropical Research Institute, Balboa, Panama
| | - Marco D Visser
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | | | - Stephen W Pacala
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
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12
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Germany MS, Bruelheide H, Erfmeier A. Janzen‐Connell effects in a forest BEF experiment: Strong distance‐dependent seedling establishment of multiple species. Ecology 2019; 100:e02736. [DOI: 10.1002/ecy.2736] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 03/10/2019] [Accepted: 03/25/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Markus S. Germany
- Institute for Ecosystem Research/Geobotany Kiel University Olshausenstrasse 75 24118 Kiel Germany
- Martin Luther University Halle‐Wittenberg Institute of Biology/Geobotany and Botanical Garden Am Kirchtor 1 06108 Halle (Saale) Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Deutscher Platz 5e 04103 Leipzig Germany
| | - Helge Bruelheide
- Martin Luther University Halle‐Wittenberg Institute of Biology/Geobotany and Botanical Garden Am Kirchtor 1 06108 Halle (Saale) Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Deutscher Platz 5e 04103 Leipzig Germany
| | - Alexandra Erfmeier
- Institute for Ecosystem Research/Geobotany Kiel University Olshausenstrasse 75 24118 Kiel Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Deutscher Platz 5e 04103 Leipzig Germany
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13
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Liu Y, He F. Incorporating the disease triangle framework for testing the effect of soil‐borne pathogens on tree species diversity. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13345] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yu Liu
- ECNU‐Alberta Joint Lab for Biodiversity Study, Tiantong Forest Ecosystem National Observation and Research Station, School of Ecology and Environmental Sciences East China Normal University Shanghai China
- Shanghai Institute of Pollution Control and Ecological Security Shanghai China
| | - Fangliang He
- ECNU‐Alberta Joint Lab for Biodiversity Study, Tiantong Forest Ecosystem National Observation and Research Station, School of Ecology and Environmental Sciences East China Normal University Shanghai China
- Department of Renewable Resources University of Alberta Edmonton Alberta Canada
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14
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Yang Q, Ding J, Siemann E. Biogeographic variation of distance‐dependent effects in an invasive tree species. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Qiang Yang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden Chinese Academy of Sciences Wuhan China
- State Key Laboratory of Grassland Agro‐ecosystems, School of Life Sciences Lanzhou University Lanzhou China
| | - Jianqing Ding
- School of Life Sciences Henan University Kaifeng China
| | - Evan Siemann
- Department of Biosciences Rice University Houston Texas
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15
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Solé R, Gripenberg S, Lewis OT, Markesteijn L, Barrios H, Ratz T, Ctvrtecka R, Butterill PT, Segar S, Metz MA, Dahl C, Rivera M, Viquez K, Ferguson W, Guevara M, Basset Y. The role of herbivorous insects and pathogens in the regeneration dynamics of Guazuma ulmifolia in Panama. NATURE CONSERVATION 2019. [DOI: 10.3897/natureconservation.32.30108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A significant proportion of the mortality of rainforest trees occurs during early life stages (seeds and seedlings), but mortality agents are often elusive. Our study investigated the role of herbivorous insects and pathogens in the early regeneration dynamics of Guazumaulmifolia (Malvaceae), an important tree species in agroforestry in Central America. We reared pre-dispersal insect seed predators from G.ulmifolia seeds in Panama. We also carried out an experiment, controlling insects and pathogens using insecticide and/or fungicide treatments, as well as seed density, and compared survivorship of G.ulmifolia seeds and seedlings among treatments and relative to untreated control plots. We observed (1) high pre-dispersal attack (92%) of the fruits of G.ulmifolia, mostly by anobiine and bruchine beetles; (2) negligible post-dispersal attack of isolated seeds by insects and pathogens; (3) slow growth and high mortality (> 95%) of seedlings after 14 weeks; (4) low insect damage on seedlings; and (5) a strong positive correlation between seedling mortality and rainfall. We conclude that for G.ulmifolia at our study site the pre-dispersal seed stage is by far the most sensitive stage to insects and that their influence on seedling mortality appears to be slight as compared to that of inclement weather. Thus, the regeneration of this important tree species may depend on effective primary dispersal of seeds by vertebrates (before most of the seed crop is lost to insects), conditioned by suitable conditions in which the seedlings can grow.
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16
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Krishnadas M, Bagchi R, Sridhara S, Comita LS. Weaker plant-enemy interactions decrease tree seedling diversity with edge-effects in a fragmented tropical forest. Nat Commun 2018; 9:4523. [PMID: 30375390 PMCID: PMC6207651 DOI: 10.1038/s41467-018-06997-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 10/05/2018] [Indexed: 11/17/2022] Open
Abstract
In fragmented forests, tree diversity declines near edges but the ecological processes underlying this loss of diversity remain poorly understood. Theory predicts that top-down regulation of seedling recruitment by insect herbivores and fungal pathogens contributes to maintaining tree diversity in forests, but it is unknown whether proximity to forest edges compromises these diversity-enhancing biotic interactions. Here we experimentally demonstrate that weakened activity of fungal pathogens and insect herbivores reduced seedling diversity, despite similar diversity of seed rain, during recruitment near forest edges in a human-modified tropical landscape. Only at sites farthest from forest edges (90-100 m) did the application of pesticides lower seedling diversity relative to control plots. Notably, lower seedling diversity corresponded with weaker density-dependent mortality attributable to insects and fungi during the seed-to-seedling transition. We provide mechanistic evidence that edge-effects can manifest as cryptic losses of crucial biotic interactions that maintain diversity.
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Affiliation(s)
- Meghna Krishnadas
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA.
| | - Robert Bagchi
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75N. Eagleville Road, Storrs, CT, 06269, USA
| | - Sachin Sridhara
- National Center for Biological Sciences, GKVK Campus, Bellary Road, Bangalore, Karnataka, 560096, India
| | - Liza S Comita
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
- Smithsonian Tropical Research Institute, Box, 0843-03092, Balboa, Ancón, Panama
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17
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Krishnadas M, Comita LS. Influence of soil pathogens on early regeneration success of tropical trees varies between forest edge and interior. Oecologia 2017; 186:259-268. [PMID: 29134399 DOI: 10.1007/s00442-017-4006-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 11/07/2017] [Indexed: 11/25/2022]
Abstract
Soil fungi are key mediators of negative density-dependent mortality in seeds and seedlings, and the ability to withstand pathogens in the shaded understory of closed-canopy forests could reinforce light gradient partitioning by tree species. For four species of tropical rainforest trees-two shade-tolerant and two shade-intolerant-we conducted a field experiment to examine the interactive effects of fungal pathogens, light, and seed density on germination and early seedling establishment. In a fully factorial design, seeds were sown into 1 m2 plots containing soil collected from underneath conspecific adult trees, with plots assigned to forest edge (high light) or shaded understory, high or low density, and fungicide or no fungicide application. We monitored total seed germination and final seedling survival over 15 weeks. Shade-intolerant species were strongly constrained by light; their seedlings survived only at the edge. Fungicide application significantly improved seedling emergence and/or survival for three of the four focal species. There were no significant interactions between fungicide and seed density, suggesting that pathogen spread with increased aggregation of seeds and seedlings did not contribute to pathogen-mediated mortality. Two species experienced significant edge-fungicide interactions, but fungicide effects in edge vs. interior forest varied with species and recruitment stage. Our results suggest that changes to plant-pathogen interactions could affect plant recruitment in human-impacted forests subject to fragmentation and edge-effects.
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Affiliation(s)
- Meghna Krishnadas
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA.
| | - Liza S Comita
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
- Smithsonian Tropical Research Institute, Box 0843-03092, Balboa, Ancón, Panama
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18
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Kuang X, Zhu K, Yuan Z, Lin F, Ye J, Wang X, Wang Y, Hao Z. Conspecific density dependence and community structure: Insights from 11 years of monitoring in an old-growth temperate forest in Northeast China. Ecol Evol 2017; 7:5191-5200. [PMID: 28770059 PMCID: PMC5528227 DOI: 10.1002/ece3.3050] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/05/2017] [Accepted: 04/12/2017] [Indexed: 11/17/2022] Open
Abstract
Forest community structure may be influenced by seedling density dependence, however, the effect is loosely coupled with population dynamics and diversity in the short term. In the long term the strength of conspecific density dependence may fluctuate over time because of seedling abundance, yet few long‐term studies exist. Based on 11 years of seedling census data and tree census data from a 25‐ha temperate forest plot in Northeast China, we used generalized linear mixed models to test the relative effects of local neighborhood density and abiotic factors on seedling density and seedling survival. Spatial point pattern analysis was used to determine if spatial patterns of saplings and juveniles, in relation to conspecific adults, were in accordance with patterns uncovered by conspecific negative density dependence at the seedling stage. Our long‐term results showed that seedling density was mainly positively affected by conspecific density, suggesting dispersal limitation of seedling development. The probability of seedling survival significantly decreased over 1 year with increasing conspecific density, indicating conspecific negative density dependence in seedling establishment. Although there was variation in conspecific negative density dependence at the seedling stage among species and across years, a dispersed pattern of conspecific saplings relative to conspecific adults at the local scale (<10 m) was observed in four of the 11 species examined. Overall, sapling spatial patterns were consistent with the impacts of conspecific density on seedling dynamics, which suggests that conspecific negative density dependence is persistent over the long term. From the long‐term perspective, conspecific density dependence is an important driver of species coexistence in temperate forests.
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Affiliation(s)
- Xu Kuang
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China.,University of Chinese Academy of Sciences Beijing China
| | - Kai Zhu
- Department of BioSciences Rice University Houston TX USA.,Department of Biology University of Texas Arlington TX USA
| | - Zuoqiang Yuan
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China
| | - Fei Lin
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China
| | - Ji Ye
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China
| | - Xugao Wang
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China
| | - Yunyun Wang
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China.,University of Chinese Academy of Sciences Beijing China
| | - Zhanqing Hao
- CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Shenyang China
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19
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Abstract
Density dependence could maintain diversity in forests, but studies continue to disagree on its role. Part of the disagreement results from the fact that different studies have evaluated different responses (survival, recruitment, or growth) of different stages (seeds, seedlings, or adults) to different inputs (density of seedlings, density or distance to adults). Most studies are conducted on a single site and thus are difficult to generalize. Using USDA Forest Service's Forest Inventory and Analysis data, we analyzed over a million seedling-to-sapling recruitment observations of 50 species from the eastern United States, controlling for the effects of climate. We focused on the per-seedling recruitment rate, because it is most likely to promote diversity and to be identified in observational or experimental data. To understand the prevalence of density dependence, we quantified the number of species with significant positive or negative effects. To understand the strength of density dependence, we determined the magnitude of effects among con- and heterospecifics, and how it changes with overall species abundance. We found that density dependence is pervasive among the 50 species, as the majority of them have significant effects and mostly negative. Density-dependence effects are stronger from conspecific than heterospecfic adult neighbors, consistent with the predictions of the Janzen-Connell hypothesis. Contrary to recent reports, density-dependence effects are more negative for common than rare species, suggesting disproportionately stronger population regulation in common species. We conclude that density dependence is pervasive, and it is strongest from conspecific neighbors of common species. Our analysis provides direct evidence that density dependence reaulates opulation dynamics of tree species in eastern U.S. forests.
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20
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Bever JD, Mangan SA, Alexander HM. Maintenance of Plant Species Diversity by Pathogens. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2015. [DOI: 10.1146/annurev-ecolsys-112414-054306] [Citation(s) in RCA: 245] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- James D. Bever
- Department of Biology, Indiana University, Bloomington, Indiana 47405;
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045
| | - Scott A. Mangan
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Helen M. Alexander
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045
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21
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Gaviria J, Engelbrecht BMJ. Effects of Drought, Pest Pressure and Light Availability on Seedling Establishment and Growth: Their Role for Distribution of Tree Species across a Tropical Rainfall Gradient. PLoS One 2015; 10:e0143955. [PMID: 26619138 PMCID: PMC4664389 DOI: 10.1371/journal.pone.0143955] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/11/2015] [Indexed: 11/18/2022] Open
Abstract
Tree species distributions associated with rainfall are among the most prominent patterns in tropical forests. Understanding the mechanisms shaping these patterns is important to project impacts of global climate change on tree distributions and diversity in the tropics. Beside direct effects of water availability, additional factors co-varying with rainfall have been hypothesized to play an important role, including pest pressure and light availability. While low water availability is expected to exclude drought-intolerant wet forest species from drier forests (physiological tolerance hypothesis), high pest pressure or low light availability are hypothesized to exclude dry forest species from wetter forests (pest pressure gradient and light availability hypothesis, respectively). To test these hypotheses at the seed-to-seedling transition, the potentially most critical stage for species discrimination, we conducted a reciprocal transplant experiment combined with a pest exclosure treatment at a wet and a dry forest site in Panama with seeds of 26 species with contrasting origin. Establishment success after one year did not reflect species distribution patterns. However, in the wet forest, wet origin species had a home advantage over dry forest species through higher growth rates. At the same time, drought limited survival of wet origin species in the dry forest, supporting the physiological tolerance hypothesis. Together these processes sort species over longer time frames, and exclude species outside their respective home range. Although we found pronounced effects of pests and some effects of light availability on the seedlings, they did not corroborate the pest pressure nor light availability hypotheses at the seed-to-seedling transition. Our results underline that changes in water availability due to climate change will have direct consequences on tree regeneration and distributions along tropical rainfall gradients, while indirect effects of light and pests are less important.
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Affiliation(s)
- Julian Gaviria
- Department of Plant Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- * E-mail:
| | - Bettina M. J. Engelbrecht
- Department of Plant Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- Smithsonian Tropical Research Institute, Balboa, Ancón, Panama
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22
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Szwagrzyk J, Gratzer G, Stępniewska H, Szewczyk J, Veselinovic B. High Reproductive Effort and Low Recruitment Rates of European Beech: Is There a Limit for the Superior Competitor? POLISH JOURNAL OF ECOLOGY 2015. [DOI: 10.3161/15052249pje2015.63.2.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Fricke EC, Tewksbury JJ, Rogers HS. Multiple natural enemies cause distance-dependent mortality at the seed-to-seedling transition. Ecol Lett 2014; 17:593-8. [DOI: 10.1111/ele.12261] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 01/14/2014] [Accepted: 01/27/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Evan C. Fricke
- Department of Biology; University of Washington; Seattle WA 98195 USA
| | | | - Haldre S. Rogers
- Department of Ecology and Evolutionary Biology; Rice University; Houston TX 77005 USA
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