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Weber-Grullon L, Gherardi L, Rutherford WA, Archer SR, Sala OE. Woody-plant encroachment: Precipitation, herbivory, and grass-competition interact to affect shrub recruitment. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2536. [PMID: 35038207 DOI: 10.1002/eap.2536] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 06/14/2021] [Accepted: 07/08/2021] [Indexed: 06/14/2023]
Abstract
Woody-plant encroachment is a global phenomenon that has been affecting the southwestern United States since the late 1800s. Drought, overgrazing, herbivory, and competition between grasses and shrub seedlings have been hypothesized as the main drivers of shrub establishment. However, there is limited knowledge about the interactions among these drivers. Using a rainfall manipulation system and various herbivore exclosures, we tested hypotheses about how precipitation (PPT), competition between grasses and shrub seedlings, and predation affect the germination and first-year survival of mesquite (Prosopis glandulosa), a shrub that has encroached in Southern Great Plains and Chihuahuan Desert grasslands. We found that mesquite germination and survival (1) increased with increasing PPT, then saturated at about the mean growing season PPT level, (2) that competition between grasses and shrub seedlings had no effect on either germination or survival, and (3) that herbivory by small mammals decreased seedling establishment and survival, while ant granivory showed no effect. In addition to its direct positive effect on survival, PPT had an indirect negative effect via increasing small mammal activity. Current models predict a decrease in PPT in the southwestern United States with increased frequency of extreme events. The non-linear nature of PPT effects on Mesquite recruitment suggests asymmetric responses, wherein drought has a relatively greater negative effect than the positive effect of wet years. Indirect effects of PPT, through its effects on small mammal abundance, highlight the importance of accounting for interactions between biotic and abiotic drivers of shrub encroachment. This study provides quantitative basis for developing tools that can inform effective shrub management strategies in grasslands and savannas.
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Affiliation(s)
- Luis Weber-Grullon
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Global Drylands Center, Arizona State University, Tempe, Arizona, USA
| | - Laureano Gherardi
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Global Drylands Center, Arizona State University, Tempe, Arizona, USA
| | - William A Rutherford
- School of Natural Resources and the Environment, The University of Arizona, Tucson, Arizona, USA
| | - Steven R Archer
- School of Natural Resources and the Environment, The University of Arizona, Tucson, Arizona, USA
| | - Osvaldo E Sala
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Global Drylands Center, Arizona State University, Tempe, Arizona, USA
- School of Sustainability, Arizona State University, Tempe, Arizona, USA
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Both Mature Patches and Expanding Areas of Juniperus thurifera Forests Are Vulnerable to Climate Change But for Different Reasons. FORESTS 2020. [DOI: 10.3390/f11090960] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Research Highlights: Water use efficiency (WUE) varied along a gradient of Juniperus thurifera (L.) forest expansion, being higher in recently colonised areas. Background and Objectives: WUE is a classic physiological process of plants that reflects the compromise between carbon assimilation and water loss and has a profound influence on their performance in water-limited environments. Forest expansion in Mediterranean regions associated with land abandonment can influence the WUE of plants due to the existence of two opposing gradients: one of favourable–unfavourable environmental conditions and another one of increased–decreased intraspecific competition, the former increasing and the latter decreasing towards the expanding front. The main objective of this study was to elucidate how the WUE of Juniperus thurifera varied along the stages of forest expansion and to provide insight on how this variation is influenced by intraspecific competition and abiotic factors. Materials and Methods: Seventeen plots at different distances from the mature forest core were selected at three sites located in the centre of the Iberian Peninsula. For 30 individuals within each plot, we measured biometric characteristics, age, tree vigour, and C/N ratio in leaves, and the leaf carbon isotope signature (δ13C (‰)) as a proxy for WUE. Around each individual, we scored the percentage cover of bare soil, stoniness, conspecifics, and other woody species. Results: WUE of J. thurifera individuals varied along the forest expansion gradient, being greater for the individuals at the expanding front than for those at the mature forest. WUE was influenced by the cover of conspecifics, tree age, and C/N ratio in leaves. This pattern reveals that less favourable environmental conditions (i.e., rocky soils and higher radiation due to lower vegetation cover) and younger trees at the expanding front are associated with increased WUE. The increased cover of conspecifics decreases irradiance at the mature forest, involving milder stress conditions than at the expanding front. Conclusions: Lower WUE in mature forests due to more favourable conditions and higher WUE due to abiotic stress at expanding fronts revealed high constraints on water economy of this tree species in these two contrasting situations. Climate change scenarios bringing increased aridity are a serious threat to Juniperus thurifera forests, affecting both mature and juvenile populations although in different ways, which deserve further research to fully unveil.
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Mellado A, Zamora R. Parasites structuring ecological communities: The mistletoe footprint in Mediterranean pine forests. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12907] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ana Mellado
- Department of EcologyTerrestrial Ecology Research GroupUniversity of Granada Granada Spain
| | - Regino Zamora
- Department of EcologyTerrestrial Ecology Research GroupUniversity of Granada Granada Spain
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Matías L, Gonzalez-Díaz P, Quero JL, Camarero JJ, Lloret F, Jump AS. Role of geographical provenance in the response of silver fir seedlings to experimental warming and drought. TREE PHYSIOLOGY 2016; 36:1236-1246. [PMID: 27273199 DOI: 10.1093/treephys/tpw049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 05/06/2016] [Indexed: 05/27/2023]
Abstract
Changes in climate can alter the distribution and population dynamics of tree species by altering their recruitment patterns, especially at range edges. However, geographical patterns of genetic diversity could buffer the negative consequences of changing climate at rear range edges where populations might also harbour individuals with drought-adapted genotypes. Silver fir (Abies alba Mill.) reaches its south-western distribution limit in the Spanish Pyrenees, where recent climatic dieback events have disproportionately affected westernmost populations. We hypothesized that silver fir populations from the eastern Pyrenees are less vulnerable to the expected changing climate due to the inclusion of drought-resistant genotypes. We performed an experiment under strictly controlled conditions simulating projected warming and drought compared with current conditions and analysed physiology, growth and survival of silver fir seedlings collected from eastern and western Pyrenean populations. Genetic analyses separated eastern and western provenances in two different lineages. Climate treatments affected seedling morphology and survival of both lineages in an overall similar way: elevated drought diminished survival and induced a higher biomass allocation to roots. Increased temperature and drought provoked more negative stem water potentials and increased δ13C ratios in leaves. Warming reduced nitrogen concentration and increased soluble sugar content in leaves, whereas drought increased nitrogen concentration. Lineage affected these physiological parameters, with western seedlings being more sensitive to warming and drought increase in terms of δ13C, nitrogen and content of soluble sugars. Our results demonstrate that, in A. alba, differences in the physiological response of this species to drought are also associated with differences in biogeographical history.
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Affiliation(s)
- Luis Matías
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
- Present address: Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), PO Box 1052, 41080 Sevilla, Spain
| | - Patricia Gonzalez-Díaz
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
| | - José L Quero
- Departamento de Ingeniería Forestal, Escuela Técnica Superior de Ingeniería Agronómica y de Montes, Universidad de Córdoba, Campus de Rabanales, Crta N-IV km 396, Córdoba 14071, Spain
| | - J Julio Camarero
- Instituto Pirenaico de Ecología (IPE-CSIC), Avda Montañana 1005, 50059 Zaragoza, Spain
| | - Francisco Lloret
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain
- Unitat d'Ecologia, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autónoma Barcelona, Cerdanyola del Vallés, 08193 Barcelona, Spain
| | - Alistair S Jump
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain
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Smith AL, Blanchard W, Blair DP, McBurney L, Banks SC, Driscoll DA, Lindenmayer DB. The dynamic regeneration niche of a forest following a rare disturbance event. DIVERS DISTRIB 2016. [DOI: 10.1111/ddi.12414] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Annabel L. Smith
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
| | - Wade Blanchard
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
| | - David P. Blair
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
| | - Lachlan McBurney
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
| | - Sam C. Banks
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
| | - Don A. Driscoll
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
- School of Life and Environmental Sciences Deakin University Geelong 221 Burwood Highway Burwood Vic. 3125 Australia
| | - David B. Lindenmayer
- Fenner School of Environment and Society Australian National University Frank Fenner Building 141 Linnaeus Way Canberra ACT 2601 Australia
- Australian Research Council Centre of Excellence for Environmental Decisions and the Long‐term Ecological Research Network, Canberra, ACT, Australia
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Ashbacher AC, Cleland EE. Native and exotic plant species show differential growth but similar functional trait responses to experimental rainfall. Ecosphere 2015. [DOI: 10.1890/es15-00059.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Zamora R, Matías L. Seed dispersers, seed predators, and browsers act synergistically as biotic filters in a mosaic landscape. PLoS One 2014; 9:e107385. [PMID: 25233342 PMCID: PMC4169421 DOI: 10.1371/journal.pone.0107385] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/28/2014] [Indexed: 11/24/2022] Open
Abstract
In this study, we analize the functional influence of animals on the plants they interact with in a mediterranean mountain. We hypothesise that seed dispersers, seed predators, and browsers can act as biotic filters for plant communities. We analyse the combined effects of mutualistic (seed dispersal) and antagonistic (seed predation, herbivory) animal interactions in a mosaic landscape of Mediterranean mountains, basing our results on observational and experimental field. Most of the dispersed seeds came from tree species, whereas the population of saplings was composed predominantly of zoochorous shrub species. Seed predators preferentially consumed seeds from tree species, whereas seeds from the dominant fleshy-fruited shrubs had a higher probability of escaping these predators. The same pattern was repeated among the different landscape units by browsers, since they browsed selectively and far more intensely on tree-species saplings than on the surrounding shrubs. In synthesis, our work identifies the major biotic processes that appear to be favoring a community dominated by shrubs versus trees because seed dispersers, predators, and herbivores together favored shrub dispersal and establishment versus trees.
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Affiliation(s)
- Regino Zamora
- Grupo de Ecología Terrestre, Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
- * E-mail:
| | - Luis Matías
- Grupo de Ecología Terrestre, Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, United Kingdom
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Assessing the Effects of Periodic Flooding on the Population Structure and Recruitment Rates of Riparian Tree Forests. WATER 2014. [DOI: 10.3390/w6092614] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Matías L, Jump AS. Impacts of predicted climate change on recruitment at the geographical limits of Scots pine. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:299-310. [PMID: 24220655 PMCID: PMC3883299 DOI: 10.1093/jxb/ert376] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ongoing changes in global climate are having a significant impact on the distribution of plant species, with effects particularly evident at range limits. We assessed the capacity of Pinus sylvestris L. populations at northernmost and southernmost limits of the distribution to cope with projected changes in climate. We investigated responses including seed germination and early seedling growth and survival, using seeds from northernmost (Kevo, Finland) and southernmost (Granada, Spain) populations. Seeds were grown under current climate conditions in each area and under temperatures increased by 5 °C, with changes in precipitation of +30% or -30% with reference to current values at northern and southern limits, respectively, in a fully factorial controlled-conditions experimental design. Increased temperatures reduced germination time and enhanced biomass gain at both range edges but reduced survival at the southern range edge. Higher precipitation also increased survival and biomass but only under a southern climate. Seeds from the southern origin emerged faster, produced bigger seedlings, allocated higher biomass to roots, and survived better than northern ones. These results indicate that recruitment will be reduced at the southernmost range of the species, whereas it will be enhanced at the northern limit, and that the southern seed sources are better adapted to survive under drier conditions. However, future climate will impose a trade-off between seedling growth and survival probabilities. At the southern range edge, higher growth may render individuals more susceptible to mortality where greater aboveground biomass results in greater water loss through evapotranspiration.
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Affiliation(s)
- Luis Matías
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
| | - Alistair S. Jump
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
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Previous Land Use Alters the Effect of Climate Change and Facilitation on Expanding Woodlands of Spanish Juniper. Ecosystems 2012. [DOI: 10.1007/s10021-012-9529-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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