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8 - Temporal niches, ecosystem function and climate change
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- By Susanne Schwinning, Texas State University, Gordon A. Fox, University of South Florida, Colleen K. Kelly, University of Oxford
- Edited by Colleen K. Kelly, University of Oxford, Michael G. Bowler, University of Oxford, Gordon A. Fox, University of South Florida
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- Book:
- Temporal Dynamics and Ecological Process
- Published online:
- 18 December 2013
- Print publication:
- 16 January 2014, pp 165-188
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- Chapter
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Summary
Introduction
This chapter differs from the main current of this volume – the identification and quantification of coexistence mechanisms associated with temporal niche dynamics – in exploring the ramifications of these processes for ecosystem ecology. The intimate link between niches and ecosystem function has long been recognised, at least in the general sense that more species, representing a greater diversity of ‘life-styles’, make more complete use of available resources and thus achieve higher levels of productivity (e.g. Preston 1948, Odum 1953, MacArthur 1955, May 1975). This broadly stated principle has been unpacked in numerous models that are more specific, for example in resource-ratio niche theory (Tilman 1982) and various forms of spatial niche theories (Loreau 1998). However, the role of temporal niches in the ecosystem context is somewhat less well developed, but critical to understanding ecological responses to climate change.
Two main features characterise worldwide, anthropogenic climate change: a general warming trend that is strongest at low latitudes and weakest at high latitudes, and complex changes in precipitation patterns, currently predicted to include reductions in precipitation at the poleward fringe of the subtropical dry belt at midlatitudes (IPCC 2007, Scheff and Frierson 2012). Both temperature and precipitation shifts, as well as their interactions, have the potential to alter environmental heterogeneity. For example, the onset of spring/summer growing seasons could be advanced (Menzel et al. 2006) and the frequency and amplitude of extreme hydrological events such as drought and flooding increased (Huntington 2006). Both temperature trends and precipitation variability are important factors in structuring temporal niches, for example by functioning as triggers of life-history events (Kelly et al., this volume, Venable and Kimball, this volume) or by controlling competitive interactions through their effects on primary production (Haxeltine and Prentice 1996). Simultaneous changes in seasonal temperature and precipitation patterns may have complex effects on populations and their interactions. Predicting such effects, and their feedbacks on climate, is one of the premiere challenges of earth system science and, in our opinion, cannot be adequately tackled without a more complete understanding of temporal niche dynamics and its role in ecosystem function.
3 - What temporal processes in trees tell us about competition, community structure and speciation
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- By Colleen K. Kelly, University of Oxford, Michael G. Bowler, University of Oxford, Gordon A. Fox, University of South Florida, J. Arturo Solís-Magallanes, Universidad de Guadalajara, J. Marcela Ramos-Tapia, Plan de Ayala, Pilar Lopera Blair, University of South Florida, Susanne Schwinning, Texas State University, John N. Williams, University of California, Jeffrey B. Joy, Simon Fraser University
- Edited by Colleen K. Kelly, University of Oxford, Michael G. Bowler, University of Oxford, Gordon A. Fox, University of South Florida
-
- Book:
- Temporal Dynamics and Ecological Process
- Published online:
- 18 December 2013
- Print publication:
- 16 January 2014, pp 41-81
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- Chapter
- Export citation
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Summary
Introduction
This chapter reviews evidence concerning the vital role that temporal dynamics can have in the ecology of trees and other long-lived species in the assembly and maintenance of natural communities. The research synthesised here was stimulated by a desire to determine the action of temporal dynamics in nature, and its implications for the nature of competition, community structure and assembly on multiple scales and across a range of climatic conditions. For the most part, the results discussed concern tropical forests, but we think they provide strong support for a more general view that can be applied across biomes. Finally, we ask if there may be a potential role for temporal dynamics in speciation, in light of what we have learned from the tropical trees.
A field programme begun in the late ’90s in the tropical dry forest of México was consciously designed to study the coexistence of closely related species in a very speciose community, but the role of temporal dynamics had not been suspected and its finding was serendipitous. With centuries-long lifespans, decades-long juvenile stages and low population turnover rates, trees are problematic candidates for demographic analyses, either observational or experimental. Unless instant death is involved, the particular hurdle with trees, as with any long-lived organism, is directly connecting any specific response in the early life of the individual with the long-term individual persistence or character of the standing population. However, trees differ from many long-lived organisms in carrying their history in their structure at both the individual and population levels. Thus, a tree population itself documents individual success over the history of the population (Parker et al. 1997, Cole et al. 2011). The distribution of a population with regard to physical conditions, size and age structure and relative to other woody species all contain information on the ecology and interactions of species (e.g. Veblen 1989, 1992, Villalba and Veblen 1998, Kelly et al. 2001) and it was the age structure of populations that revealed the action of temporal dynamics at Chamela Biological Station.