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Ramage BS, Johnson DJ, Chan DM. Effects of drought, disturbance, and biotic neighborhood on experimental tree seedling performance. Ecol Evol 2023; 13:e10413. [PMID: 37593754 PMCID: PMC10427772 DOI: 10.1002/ece3.10413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 08/19/2023] Open
Abstract
Forest biodiversity is likely maintained by a complex suite of interacting drivers that vary in importance across both space and time. Contributing factors include disturbance, interannual variation in abiotic variables, and biotic neighborhood effects. To probe ongoing uncertainties and potential interactions, we investigated tree seedling performance in a temperate mid-Atlantic forest ecosystem. We planted seedlings of five native tree species in mapped study plots, half of which were subjected to disturbance, and then monitored seedling survival, height growth, and foliar condition. The final year of data collection encompassed a drought, enabling comparison between intervals varying in water availability. Seedling performance was analyzed as a function of canopy cover and biotic neighborhood (conspecific and heterospecific abundance), including interactions, with separate generalized linear mixed models fit for each interval. All species exhibited: (a) pronounced declines in height growth during the drought year, (b) detrimental effects of adult conspecifics, and (c) beneficial effects of canopy openness. However, despite these consistencies, there was considerable variation across species in terms of the relevant predictors for each response variable in each interval. Our results suggest that drought may strengthen or reveal conspecific inhibition in some instances while weakening it or obscuring it in others, and that some forms of conspecific inhibition may manifest only under particular canopy conditions (although given the inconsistency of our findings, we are not convinced that conspecific inhibition is critical for diversity maintenance in our study system). Overall, our work reveals a complex forest ecosystem that appears simultaneously and interactively governed by biotic neighborhood structure (e.g., conspecific and/or heterospecific abundance), local habitat conditions (e.g., canopy cover), and interannual variability (e.g., drought).
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Affiliation(s)
| | - Daniel J. Johnson
- School of Forest, Fisheries, & Geomatics sciencesUniversity of FloridaGainesvilleFloridaUSA
| | - David M. Chan
- Department of Mathematics and Applied MathematicsVirginia Commonwealth UniversityRichmondVirginiaUSA
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2
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Jevon FV, De La Cruz D, LaManna JA, Lang AK, Orwig DA, Record S, Kouba PV, Ayres MP, Matthes JH. Experimental and observational evidence of negative conspecific density dependence in temperate ectomycorrhizal trees. Ecology 2022; 103:e3808. [PMID: 35792423 DOI: 10.1002/ecy.3808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 02/25/2022] [Accepted: 03/18/2022] [Indexed: 11/09/2022]
Abstract
Conspecific negative density dependence (CNDD) promotes tree species diversity by reducing recruitment near conspecific adults due to biotic feedbacks from herbivores, pathogens, or competitors. While this process is well-described in tropical forests, tests of temperate tree species range from strong positive to strong negative density dependence. To explain this, several studies have suggested that tree species traits may help predict the strength and direction of density dependence: for example, ectomycorrhizal-associated tree species typically exhibit either positive or weaker negative conspecific density dependence. More generally, the strength of density dependence may be predictably related to other species-specific ecological attributes such as shade tolerance, or the relative local abundance of a species. To test the strength of density dependence and whether it affects seedling community diversity in a temperate forest, we tracked the survival of seedlings of three ectomycorrhizal-associated species experimentally planted beneath conspecific and heterospecific adults on the Prospect Hill tract of the Harvard Forest, in Massachusetts, USA. Experimental seedling survival was always lower under conspecific adults, which increased seedling community diversity in one of six treatments. We compared these results to evidence of CNDD from observed sapling survival patterns of 28 species over approximately 8 years in an adjacent 35-hectare forest plot. We tested whether species-specific estimates of CNDD were associated with mycorrhizal association, shade tolerance, and local abundance. We found evidence of significant, negative conspecific density dependence (CNDD) in 23 of 28 species, and positive conspecific density dependence in two species. Contrary to our expectations, ectomycorrhizal-associated species generally exhibited stronger (e.g. more negative) CNDD than arbuscular mycorrhizal- associated species. CNDD was also stronger in more shade tolerant species but was not associated with local abundance. Conspecific adult trees often have a negative influence on seedling survival in temperate forests, particularly for tree species with certain traits. Here we found strong experimental and observational evidence that ectomycorrhizal-associating species consistently exhibit CNDD. Moreover, similarities in the relative strength of density dependence from experiments and observations of sapling mortality suggest a mechanistic link between negative effects of conspecific adults on seedling and sapling survival and local tree species distributions.
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Affiliation(s)
- Fiona V Jevon
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
| | - Dayna De La Cruz
- Department of Biological Sciences, Wellesley College, Wellesley, MA, USA
| | - Joseph A LaManna
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
| | - Ashley K Lang
- Department of Biological Sciences, Indiana University, Bloomington, IN, USA
| | - David A Orwig
- Harvard Forest, Harvard University, Petersham, MA, USA
| | - Sydne Record
- Department of Biology, Bryn Mawr College, Bryn Mawr, Pennsylvania, USA
| | - Paige V Kouba
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Matthew P Ayres
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
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He Y, Liu H, Yang Q, Cao Y, Yin H, Zhou Z, Yu Q, Wang X. Neighborhood Effects on Tree Mortality Depend on Life Stage of Neighbors. FRONTIERS IN PLANT SCIENCE 2022; 13:838046. [PMID: 35273630 PMCID: PMC8902350 DOI: 10.3389/fpls.2022.838046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
Neighborhood effects are a crucial ecological processes that allow species to coexist in a forest. Conspecific and heterospecific neighbors, as major group classifications, affect tree mortality through various mechanisms associated with neighbor life stages. However, the influence of neighbor life stages on neighborhood effects and by what mechanisms remains a knowledge gap. Here we censused the mortality of 82,202 trees belonging to 30 species in a 20-ha subtropical forest and classified their neighbors into the following life stages: earlier, same and later. Next, we implemented generalized linear mixed models to estimate the effect of neighbors at different life stages on tree mortality. Our results showed that conspecific later stage neighbors had a positive effect on tree mortality overall, while conspecific earlier stage neighbors had a negative effect on tree mortality. Furthermore, these opposing effects appear to offset each other so that the overall effect of conspecific neighbors on tree mortality is weakened. In contrast, heterospecific neighbors had a decreasing effect on tree mortality overall. These effects are consistent with those of later stage heterospecific neighbors. Our findings demonstrate that neighbors strongly impact tree mortality, and their specific effects are closely related to neighbor life stages. Further, any single effect from one neighbor life stage may disturb or dominate the total effects of the neighbors. Therefore, the neighbors must be divided into different life stages to best explain the neighborhood effect on forest dynamics.
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Affiliation(s)
| | - Heming Liu
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
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4
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Brown AJ, White PS, Peet RK. Environmental context alters the magnitude of conspecific negative density dependence in a temperate forest. Ecosphere 2021. [DOI: 10.1002/ecs2.3406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Alissa J. Brown
- Department of Biology University of North Carolina at Chapel Hill 120 South Road Chapel Hill North Carolina27599USA
| | - Peter S. White
- Department of Biology University of North Carolina at Chapel Hill 120 South Road Chapel Hill North Carolina27599USA
- Curriculum for the Environment and Ecology University of North Carolina at Chapel Hill Chapel Hill North Carolina27599USA
| | - Robert K. Peet
- Department of Biology University of North Carolina at Chapel Hill 120 South Road Chapel Hill North Carolina27599USA
- Curriculum for the Environment and Ecology University of North Carolina at Chapel Hill Chapel Hill North Carolina27599USA
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Zang L, Xu H, Li Y, Zang R. Conspecific negative density dependence of trees varies with plant functional traits and environmental conditions across scales in a 60‐ha tropical rainforest dynamics plot. Biotropica 2021. [DOI: 10.1111/btp.12910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Lipeng Zang
- Center of Forest Ecology College of Forestry Guizhou University Guiyang China
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Research Institute of Forest Ecology, Environment and Protection Chinese Academy of Forestry Beijing China
- Co‐Innovation Center for Sustainable Forestry in Southern China Nanjing Forestry University Nanjing China
| | - Han Xu
- Institute of Tropical Forestry Chinese Academy of Forestry Guangzhou China
| | - Yide Li
- Institute of Tropical Forestry Chinese Academy of Forestry Guangzhou China
| | - Runguo Zang
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Research Institute of Forest Ecology, Environment and Protection Chinese Academy of Forestry Beijing China
- Co‐Innovation Center for Sustainable Forestry in Southern China Nanjing Forestry University Nanjing China
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6
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Relationship between Soil Fungi and Seedling Density in the Vicinity of Adult Conspecifics in an Arid Desert Forest. FORESTS 2021. [DOI: 10.3390/f12010092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Research Highlights: 1. Soil fungi have a higher influence on seedling density compared to soil environmental factors; 2. Host-specific pathogens and beneficial fungi affect seeding density via different influencing mechanisms. Background and Objectives: The growth and development of seedlings are the key processes that affect forest regeneration and maintain community dynamics. However, the influencing factors of seedling growth around their adult conspecifics are not clear in arid desert forests. Probing the intrinsic relations among soil fungi, soil environmental factors (pH, water content, salinity, and nutrition), and seedling density will improve our understanding of forest development and provide a theoretical basis for forest management and protection. Materials and Methods: Four experimental plot types, depending on the distance to adult conspecifics, were set in an arid desert forest. Soil environmental factors, the diversity and composition of the soil fungal community, and the seedlings’ density and height were measured in the four experimental plot types, and their mutual relations were analyzed. Results: Seedling density as well as the diversity and composition of the soil fungal community varied significantly among the four plot types (p < 0.05). Soil environmental factors, especially soil salinity, pH, and soil water content, had significant influences on the seedling density and diversity and composition of the soil fungal community. The contribution of soil fungi (72.61%) to the variation in seedling density was much higher than the soil environmental factors (27.39%). The contribution of detrimental fungi to the variation in seedling density was higher than the beneficial fungi. Conclusions: Soil fungi mostly affected the distribution of seedling density in the vicinity of adult conspecifics in an arid desert forest. The distribution of seedling density in the vicinity of adults was mainly influenced by the detrimental fungi, while the adults in the periphery area was mainly influenced by the beneficial fungi.
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Kirk DA, Brice M, Bradstreet MS, Elliott KA. Changes in beta diversity and species functional traits differ between saplings and mature trees in an old-growth forest. Ecol Evol 2021; 11:58-88. [PMID: 33437415 PMCID: PMC7790643 DOI: 10.1002/ece3.6913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 07/27/2020] [Accepted: 09/08/2020] [Indexed: 11/26/2022] Open
Abstract
Invasion by generalist tree species can cause biotic homogenization, and such community impoverishment is likely more important in rare forest types. We quantified changes in tree diversity within Carolinian (range in Central Hardwood Forest), central (range in Central Hardwood Forest and Northern Hardwood-Conifer Forest), and northern species [range reached Northern-Conifer-Hardwood/closed Boreal (spruce-Fir) Forest] in an old forest tract in southern Canada at points surveyed 24 years apart. We asked: How did mature tree and sapling composition and abundance change for the three species' groups? Did those changes lead to biotic homogenization? Can species' changes be explained by community traits? We tested for differences in temporal and spatial tree β-diversity, as well as forest composition and structure, using univariate/multivariate analyses and a community trait-based approach to identify drivers of change. Major increases occurred in abundance for mature Acer rubrum (northern), while other species decreased (Fraxinus americana, Populus grandidentata); declines were found in A. saccharinum (central) and Cornus florida (Carolinian). Species composition of saplings, but not mature trees, changed due to replacement; no evidence for biotic homogenization existed in either cohort. As a group, northern mature tree species increased significantly, while central species decreased; saplings of pooled Carolinian species also declined. Shade tolerance in mature trees increased, reflecting successional changes, while drought tolerance decreased, perhaps due to changing temperatures, altered precipitation or ground water levels. Saplings showed declines in all traits, probably because of compositional change. Our results demonstrated that saplings can more closely reflect change in forest dynamics than mature trees, especially over short time periods. Based on sapling trends, this remnant could ultimately transition to a mesophytic hardwood stand dominated by A. rubrum and other shade-tolerant species, creating a more homogeneous forest. While encouraging regeneration for Carolinian and central tree species could ensure high levels of diversity are conserved in the future, it is important to balance this with the primary management goal of maintaining the forest's old-growth characteristics.
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Affiliation(s)
| | - Marie‐Hélène Brice
- Département de Sciences BiologiquesUniversité de MontréalMontréalQCCanada
- Québec Centre for Biodiversity SciencesMcGill UniversityMontréalQCCanada
| | | | - Ken A. Elliott
- Divisional Support SectionIntegration BranchOntario Ministry of Natural Resources and ForestryPeterboroughONCanada
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Hülsmann L, Chisholm RA, Hartig F. Is Variation in Conspecific Negative Density Dependence Driving Tree Diversity Patterns at Large Scales? Trends Ecol Evol 2020; 36:151-163. [PMID: 33589047 DOI: 10.1016/j.tree.2020.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 09/28/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023]
Abstract
Half a century ago, Janzen and Connell hypothesized that the high tree species diversity in tropical forests is maintained by specialized natural enemies. Along with other mechanisms, these can cause conspecific negative density dependence (CNDD) and thus maintain species diversity. Numerous studies have measured proxies of CNDD worldwide, but doubt about its relative importance remains. We find ample evidence for CNDD in local populations, but methodological limitations make it difficult to assess if CNDD scales up to control community diversity and thereby local and global biodiversity patterns. A combination of more robust statistical methods, new study designs, and eco-evolutionary models are needed to provide a more definite evaluation of the importance of CNDD for geographic variation in plant species diversity.
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Affiliation(s)
- Lisa Hülsmann
- Theoretical Ecology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany.
| | - Ryan A Chisholm
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Florian Hartig
- Theoretical Ecology, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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9
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Fan C, Tan L, Zhang C, Zhao X, Gao L, von Gadow K. Scale-dependent effects of neighborhood biodiversity on individual tree productivity in a coniferous and broad-leaved mixed forest in China. Ecol Evol 2020; 10:8225-8234. [PMID: 32788974 PMCID: PMC7417230 DOI: 10.1002/ece3.6530] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/14/2020] [Accepted: 06/01/2020] [Indexed: 11/08/2022] Open
Abstract
The relationship between biodiversity and productivity has stimulated an increasing body of research over the past decades, and this topic still occupies a central place in ecology. While most studies have focused on biomass production in quadrats or plots, few have investigated the scale-dependent relationship from an individual plant perspective. We present an analysis of the effects of biodiversity (species diversity and functional diversity) on individual tree growth with a data set of 16,060 growth records from a 30-ha temperate forest plot using spatially explicit individual tree-based methods. A significant relationship between species diversity and tree growth was found at the individual tree level in our study. The magnitude and direction of biodiversity effects varies with the spatial scale. We found positive effects of species diversity on tree growth at scales exceeding 9 m. Individual tree growth rates increased when there was a greater diversity of species in the neighborhood of the focal tree, which provides evidence of a niche complementarity effect. At small scales (3-5 m), species diversity had negative effects on tree growth, suggesting that competition is more prevalent than complementarity or facilitation in these close neighborhoods. The results also revealed many confounding factors which influence tree growth, such as elevation and available sun light. We conclude that the use of individual tree-based methods may lead to a better understanding of the biodiversity-productivity relationship in forest communities.
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Affiliation(s)
- Chunyu Fan
- Research Center of Forest Management Engineering of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijingChina
| | - Lingzhao Tan
- Research Center of Forest Management Engineering of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijingChina
| | - Chunyu Zhang
- Research Center of Forest Management Engineering of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijingChina
| | - Xiuhai Zhao
- Research Center of Forest Management Engineering of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijingChina
| | - Lushuang Gao
- Research Center of Forest Management Engineering of State Forestry and Grassland AdministrationBeijing Forestry UniversityBeijingChina
| | - Klaus von Gadow
- Faculty of Forestry and Forest EcologyGeorg‐August‐University GöttingenGöttingenGermany
- Department of Forest and Wood ScienceUniversity of StellenboschStellenboschSouth Africa
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10
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Cobo‐Quinche J, Endara M, Valencia R, Muñoz‐Upegui D, Cárdenas RE. Physical, but not chemical, antiherbivore defense expression is related to the clustered spatial distribution of tropical trees in an Amazonian forest. Ecol Evol 2019; 9:1750-1763. [PMID: 30847070 PMCID: PMC6392389 DOI: 10.1002/ece3.4859] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/10/2018] [Accepted: 11/30/2018] [Indexed: 12/23/2022] Open
Abstract
The conspecific negative density dependence hypothesis states that mortality of young trees (seedlings and saplings) is higher near conspecific adults due to mechanisms such as allelopathy, intraspecific competition, and pest facilitation, explaining why in the tropics, most of plant species tend to be rare and live dispersed. However, there are some tree species that defy this expectation and grow in large clusters of conspecific juveniles and adults. We hypothesize that conspecifics living in clusters show higher and/or more variable defensive profiles than conspecifics with dispersed distributions.We evaluated our hypothesis by assessing the expression of physical leaf traits (thickness, and the resistance to punch, tear and shear) and leaf chemical defenses for six clustered and six non-clustered tree species in Yasuní National Park, Ecuadorian Amazon. We ask ourselves whether (a) clustered species have leaves with higher physical resistance to damage and more chemical defenses variability than non-clustered species; (b) saplings of clustered species may show higher physical resistance to damage and higher variation on chemical leaf defenses than their conspecific adults, and (c) saplings of non-clustered species show lower resistance to physical damage and lower variation in chemical defenses compared to conspecific adults.Overall, our study did not support any of our hypotheses. Remarkably, we found that soluble metabolites were significantly species-specific.Our study suggests that plants physical but not chemical leaf antiherbivore defenses may be a crucial strategy for explaining survivorship of clustered species. Trees in Yasuní may also fall along a suite of tolerance/escape/defense strategies based on limitations of each species physiological constraints for survival and establishment. We conclude that other mechanisms, such as those related to indirect defenses, soil nutrient exploitation efficiency, volatile organic compounds, delayed leaf-greening, and seed dispersal mechanisms, shall be evaluated to understand conspecific coexistence in this forest.
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Affiliation(s)
- Johanna Cobo‐Quinche
- Herbario QCA, Laboratorio de Ecología de Plantas, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y NaturalesPontificia Universidad Católica del EcuadorQuitoEcuador
| | - María‐José Endara
- Department of BiologyUniversity of UtahSalt Lake CityUtah
- Centro de Investigación de la Biodiversidad y Cambio ClimáticoUniversidad Tecnológica IndoaméricaQuitoEcuador
| | - Renato Valencia
- Herbario QCA, Laboratorio de Ecología de Plantas, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y NaturalesPontificia Universidad Católica del EcuadorQuitoEcuador
| | - Dolly Muñoz‐Upegui
- Museo de Zoología QCAZ, Laboratorio de Entomología, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y NaturalesPontificia Universidad Católica del EcuadorQuitoEcuador
| | - Rafael E. Cárdenas
- Herbario QCA, Laboratorio de Ecología de Plantas, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y NaturalesPontificia Universidad Católica del EcuadorQuitoEcuador
- Museo de Zoología QCAZ, Laboratorio de Entomología, Escuela de Ciencias Biológicas, Facultad de Ciencias Exactas y NaturalesPontificia Universidad Católica del EcuadorQuitoEcuador
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11
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Aussenac R, Bergeron Y, Gravel D, Drobyshev I. Interactions among trees: A key element in the stabilising effect of species diversity on forest growth. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13257] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raphaël Aussenac
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de recherche sur les forêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT) Rouyn‐Noranda Québec Canada
| | - Yves Bergeron
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de recherche sur les forêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT) Rouyn‐Noranda Québec Canada
| | - Dominique Gravel
- Chaire de recherche en écologie intégrativeDépartement de biologieFaculté des sciencesUniversité de Sherbrooke Sherbrooke Québec Canada
| | - Igor Drobyshev
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de recherche sur les forêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT) Rouyn‐Noranda Québec Canada
- Southern Swedish Forest Research CentreSwedish University of Agricultural Sciences Alnarp Sweden
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12
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Chen Y, Umaña MN, Uriarte M, Yu S. Abundance-dependent effects of neighbourhood dissimilarity and growth rank reversal in a neotropical forest. Proc Biol Sci 2018; 285:20172878. [PMID: 29618550 PMCID: PMC5904314 DOI: 10.1098/rspb.2017.2878] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/15/2018] [Indexed: 12/19/2022] Open
Abstract
Why tropical forests harbour an exceptional number of species with striking differences in abundances remains an open question. We propose a theoretical framework to address this question in which rare species may have different extirpation risks depending on species ranks in tree growth and sensitivities to neighbourhood interactions. To evaluate the framework, we studied tree growth and its responses to neighbourhood dissimilarity (ND) in traits and phylogeny for 146 species in a neotropical forest. We found that tree growth was positively related to ND, and common species were more strongly affected by ND than rare species, which may help delay dominance of common species. Rare species grew more slowly at the community-wide average ND than common species. But rare species grew faster when common species tended to dominate locally, which may help reduce extirpation risk of rare species. Our study highlights that tree growth rank among species depends on their responses to neighbourhood interactions, which can be important in fostering diversity maintenance in tropical forests.
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Affiliation(s)
- Yuxin Chen
- School of Life Sciences/State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - María Natalia Umaña
- Department of Biology, University of Maryland, College Park, MD, USA
- Yale School of Forestry and Environmental Studies, New Haven, CT, USA
| | - María Uriarte
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
| | - Shixiao Yu
- School of Life Sciences/State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
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13
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Ramage BS, Johnson DJ, Gonzalez-Akre E, McShea WJ, Anderson-Teixeira KJ, Bourg NA, Clay K. Sapling growth rates reveal conspecific negative density dependence in a temperate forest. Ecol Evol 2017; 7:7661-7671. [PMID: 29043023 PMCID: PMC5632615 DOI: 10.1002/ece3.3298] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/27/2017] [Accepted: 07/03/2017] [Indexed: 01/25/2023] Open
Abstract
Local tree species diversity is maintained in part by conspecific negative density dependence (CNDD). This pervasive mechanism occurs in a variety of forms and ecosystems, but research to date has been heavily skewed toward tree seedling survival in tropical forests. To evaluate CNDD more broadly, we investigated how sapling growth rates were affected by conspecific adult neighbors in a fully mapped 25.6 ha temperate deciduous forest. We examined growth rates as a function of the local adult tree neighborhood (via spatial autoregressive modeling) and compared the spatial positioning of faster‐growing and slower‐growing saplings with respect to adult conspecific and heterospecific trees (via bivariate point pattern analysis). In addition, to determine whether CNDD‐driven variation in growth rates leaves a corresponding spatial signal, we extended our point pattern analysis to a static, growth‐independent comparison of saplings and the next larger size class. We found that negative conspecific effects on sapling growth were most prevalent. Five of the nine species that were sufficiently abundant for analysis exhibited CNDD, while only one species showed evidence of a positive conspecific effect, and one or two species, depending on the analysis, displayed heterospecific effects. There was general agreement between the autoregressive models and the point pattern analyses based on sapling growth rates, but point pattern analyses based on single‐point‐in‐time size classes yielded results that differed markedly from the other two approaches. Our work adds to the growing body of evidence that CNDD is an important force in temperate forests, and demonstrates that this process extends to sapling growth rates. Further, our findings indicate that point pattern analyses based solely on size classes may fail to detect the process of interest (e.g., neighborhood‐driven variation in growth rates), in part due to the confounding of tree size and age.
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Affiliation(s)
| | - Daniel J Johnson
- Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos NM USA
| | - Erika Gonzalez-Akre
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA
| | - William J McShea
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA
| | - Kristina J Anderson-Teixeira
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA.,Center for Tropical Forest Science Smithsonian Tropical Research Institute Panama City Panama
| | - Norman A Bourg
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA.,U.S. Geological Survey National Research Program - Eastern Branch Reston VA USA
| | - Keith Clay
- Department of Biology Indiana University Bloomington IN USA
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