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van Breugel M, Bongers F, Norden N, Meave JA, Amissah L, Chanthorn W, Chazdon R, Craven D, Farrior C, Hall JS, Hérault B, Jakovac C, Lebrija-Trejos E, Martínez-Ramos M, Muñoz R, Poorter L, Rüger N, van der Sande M, Dent DH. Feedback loops drive ecological succession: towards a unified conceptual framework. Biol Rev Camb Philos Soc 2024; 99:928-949. [PMID: 38226776 DOI: 10.1111/brv.13051] [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: 06/28/2023] [Revised: 12/29/2023] [Accepted: 12/29/2023] [Indexed: 01/17/2024]
Abstract
The core principle shared by most theories and models of succession is that, following a major disturbance, plant-environment feedback dynamics drive a directional change in the plant community. The most commonly studied feedback loops are those in which the regrowth of the plant community causes changes to the abiotic (e.g. soil nutrients) or biotic (e.g. dispersers) environment, which differentially affect species availability or performance. This, in turn, leads to shifts in the species composition of the plant community. However, there are many other PE feedback loops that potentially drive succession, each of which can be considered a model of succession. While plant-environment feedback loops in principle generate predictable successional trajectories, succession is generally observed to be highly variable. Factors contributing to this variability are the stochastic processes involved in feedback dynamics, such as individual mortality and seed dispersal, and extrinsic causes of succession, which are not affected by changes in the plant community but do affect species performance or availability. Both can lead to variation in the identity of dominant species within communities. This, in turn, leads to further contingencies if these species differ in their effect on their environment (priority effects). Predictability and variability are thus intrinsically linked features of ecological succession. We present a new conceptual framework of ecological succession that integrates the propositions discussed above. This framework defines seven general causes: landscape context, disturbance and land-use, biotic factors, abiotic factors, species availability, species performance, and the plant community. When involved in a feedback loop, these general causes drive succession and when not, they are extrinsic causes that create variability in successional trajectories and dynamics. The proposed framework provides a guide for linking these general causes into causal pathways that represent specific models of succession. Our framework represents a systematic approach to identifying the main feedback processes and causes of variation at different successional stages. It can be used for systematic comparisons among study sites and along environmental gradients, to conceptualise studies, and to guide the formulation of research questions and design of field studies. Mapping an extensive field study onto our conceptual framework revealed that the pathways representing the study's empirical outcomes and conceptual model had important differences, underlining the need to move beyond the conceptual models that currently dominate in specific fields and to find ways to examine the importance of and interactions among alternative causal pathways of succession. To further this aim, we argue for integrating long-term studies across environmental and anthropogenic gradients, combined with controlled experiments and dynamic modelling.
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Affiliation(s)
- Michiel van Breugel
- Department of Geography, National University of Singapore, Arts Link, #03-01 Block AS2, 117570, Singapore
- Yale-NUS College, 16 College Avenue West, Singapore, 138527, Singapore
- Smithsonian Tropical Research Institute, Roosevelt Ave. Tupper Building - 401, Panama City, 0843-03092, Panama
| | - Frans Bongers
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Natalia Norden
- Centro de Estudios Socioecológicos y Cambio Global, Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Avenida Circunvalar #16-20, Bogotá, Colombia
| | - Jorge A Meave
- Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México. Circuito Exterior s/n, Ciudad Universitaria, Coyoacán, Ciudad de México, C.P. 04510, Mexico
| | - Lucy Amissah
- CSIR-Forestry Research Institute of Ghana, UPO Box 63, Kumasi, Ghana
| | - Wirong Chanthorn
- Department of Environmental Technology and Management, Faculty of Environment, Kasetsart University, 50 Ngamwongwan Road, Jatujak District, 10900, Thailand
| | - Robin Chazdon
- Forest Research Institute, University of the Sunshine Coast, 90 Sippy Downs Dr, Sippy Downs, Queensland, 4556, Australia
| | - Dylan Craven
- Center for Genomics, Ecology & Environment, Universidad Mayor, Camino La Piramide 5750, Huechuraba, Santiago, 8580745, Chile
| | - Caroline Farrior
- Department of Integrative Biology, University of Texas at Austin, 2415 Speedway, Stop C0930, Austin, Texas, 78705, USA
| | - Jefferson S Hall
- Smithsonian Tropical Research Institute, Roosevelt Ave. Tupper Building - 401, Panama City, 0843-03092, Panama
| | - Bruno Hérault
- CIRAD, UPR Forêts et Sociétés, F-34398 Montpellier, France & Forêts et Sociétés, Univ Montpellier, CIRAD, Montpellier, France
| | - Catarina Jakovac
- Departamento de Fitotecnia, Centro de Ciências Agrárias, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, 1346, 88034-000, Florianópolis, Brazil
| | - Edwin Lebrija-Trejos
- Department of Biology and Environment, University of Haifa-Oranim, Tivon, 36006, Israel
| | - Miguel Martínez-Ramos
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Antigua Carretera a Pátzcuaro # 8701, Col. Ex-Hacienda de San José de la Huerta, CP 58190, Morelia, Michoacán, Mexico
| | - Rodrigo Muñoz
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Lourens Poorter
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Nadja Rüger
- Smithsonian Tropical Research Institute, Roosevelt Ave. Tupper Building - 401, Panama City, 0843-03092, Panama
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103, Leipzig, Germany
- Department of Economics, Institute of Empirical Economic Research, University of Leipzig, Grimmaische Str. 12, 04109, Leipzig, Germany
| | - Masha van der Sande
- Forest Ecology and Forest Management Group, Wageningen University & Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Daisy H Dent
- Smithsonian Tropical Research Institute, Roosevelt Ave. Tupper Building - 401, Panama City, 0843-03092, Panama
- ETH Zürich, Department of Environmental Systems Science, Institute for Integrative Biology, Universitätstrasse 16, 8092, Zürich, Switzerland
- Max Planck Institute for Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany
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Zhu J, Jiang L, Chen L, Jin X, Xing C, Liu J, Yang Y, He Z. Tree seedling growth allocation of Castanopsis kawakamii is determined by seed-relative positions. FRONTIERS IN PLANT SCIENCE 2023; 14:1099139. [PMID: 37332687 PMCID: PMC10272420 DOI: 10.3389/fpls.2023.1099139] [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: 11/15/2022] [Accepted: 05/10/2023] [Indexed: 06/20/2023]
Abstract
Plants allocate growth to different organs as a strategy to obtain limiting resources in different environments. Tree seeds that fall from a mother tree settle on, within, or below the forest floor and litter layer, and their relative positions can determine seedling biomass and nutrient allocation and ultimately affect survival to the sapling stage. However, how emerged seedling biomass and nutrients of each organ are affected by seeds in different positions is not yet completely understood in subtropical forests. Therefore, an experiment was conducted with seeds positioned above the litter layers of different thicknesses, on the forest floor, and beneath the litter layer, and the influences of seed position on biomass allocation and nutrient use efficiency of emerged seedlings of Castanopsis kawakamii was examined. The aim of the study was to determine the optimal seed position to promote regeneration. Allocation strategies were well coordinated in the emerged seedlings from different seed positions. Seedlings from seeds positioned above litter layers of different thicknesses (~40 and 80 g of litter) allocated growth to leaf tissue at the expense of root tissue (lower root mass fraction) and increased nitrogen (N) and phosphorus (P) accumulation and nutrient use efficiency. Seedlings from seeds positioned beneath a deep litter layer allocated most growth to roots (high root: shoot ratio, root mass fraction) to capture available resources at the expense of leaf growth. Seedlings from seeds positioned on the forest floor allocated most growth to roots to obtain limiting resources. Further, we also found that these traits were clustered into three groups based on trait similarity, and the cumulative interpretation rate was 74.2%. Thus, seed relative positions significantly affected seedling growth by altering the allocation of resources to different organs. The different strategies indicated that root N:P ratios (entropy weight vector was 0.078) and P nutrient use efficiency were essential factors affecting seedling growth in the subtropical forest. Of the seed positions analyzed, beneath a moderate litter layer (~40 g of litter) was the most suitable position for the growth and survival of Castanopsis seedlings. In future studies, field and lab experiments will be combined to reveal the mechanisms underlying forest regeneration.
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Affiliation(s)
- Jing Zhu
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lan Jiang
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lyuyi Chen
- Entomology and Nematology Department, University of Florida, Gainesville, FL, United States
| | - Xing Jin
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Cong Xing
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jinfu Liu
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yongchuan Yang
- College of Environment and Ecology, Chongqing University, Chongqing, China
| | - Zhongsheng He
- Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China
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Rehm EM, D'Antonio C, Yelenik S. Crossing the threshold: Invasive grasses inhibit forest restoration on Hawaiian islands. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2841. [PMID: 36920234 DOI: 10.1002/eap.2841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/20/2023] [Accepted: 02/24/2023] [Indexed: 06/02/2023]
Abstract
Forest removal for livestock grazing is a striking example of human-caused state change leading to a stable, undesirable invasive grass system that is resistant to restoration efforts. Understanding which factors lead to resilience to the alternative grass state can greatly benefit managers when planning forest restoration. We address how thresholds of grass cover and seed rain might influence forest recovery in a restoration project on Hawai'i Island, USA. Since the 1980s, over 400,000 Acacia koa (koa) trees have been planted across degraded pasture, and invasive grasses still dominate the understory with no native woody-plant recruitment. Between this koa/grass matrix are remnant native Metrosideros polymorpha ('ōhi'a) trees beneath which native woody plants naturally recruit. We tested whether there were threshold levels of native woody understory that accelerate recruitment under both tree species by monitoring seed rain at 40 trees (20 koa and 'ōhi'a) with a range of native woody understory basal area (BA). We found a positive relationship between total seed rain (but not bird-dispersed seed rain) and native woody BA and a negative relationship between native woody BA and grass cover, with no indication of threshold dynamics. We also experimentally combined grass removal levels with seed rain density (six levels) of two common understory species in plots under koa (n = 9) and remnant 'ōhi'a (n = 9). Few seedlings emerged when no grass was removed despite adding seeds at densities two to 75 times higher than naturally occurring. However, seedling recruitment increased two to three times once at least 50% of grass was removed. Existing survey data of naturally occurring seedlings also supported a threshold of grass cover below which seedlings were able to establish. Thus, removal of all grasses is not necessary to achieve system responses: Even moderate reductions (~50%) can increase rates of native woody recruitment. The nonlinear thresholds found here highlight how incremental changes to an inhibitory factor lead to limited restoration success until a threshold is crossed. The resources needed to fully eradicate an invasive species may be unwarranted for state change, making understanding where thresholds lie of the utmost importance to prioritize resources.
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Affiliation(s)
- Evan M Rehm
- Biology Department, Austin Peay State University, Clarksville, Tennessee, USA
| | - Carla D'Antonio
- Department of Ecology, Evolution and Marine Biology, University of California at Santa Barbara, Santa Barbara, California, USA
| | - Stephanie Yelenik
- U.S. Geological Survey, Pacific Island Ecosystems Research Center, Volcano, Hawaii, USA
- Rocky Mountain Research Station, US Forest Service, Reno, Nevada, USA
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