The Role of Disturbance in Natural Communities
01 Nov 1984-Annual Review of Ecology, Evolution, and Systematics (Annual Reviews 4139 El Camino Way, P.O. Box 10139, Palo Alto, CA 94303-0139, USA)-Vol. 15, Iss: 1, pp 353-391
TL;DR: For many communities, a self-reproducing climax state may only exist as an average condition on a relatively large spatial scale, and even that has yet to be rigorously demonstrated.
Abstract: Two features characterize all natural communities. First, they are dynamic systems. The densities and age-structures of populations change with time, as do the relative abundances of species; local extinctions are commonplace (37). For many communities, a self-reproducing climax state may only exist as an average condition on a relatively large spatial scale, and even that has yet to be rigorously demonstrated (36). The idea that equilibrium is rarely achieved on the local scale was expressed decades ago by a number of forest ecologists (e.g. 10 1, 168). One might even argue that continued application of the concept of climax to natural systems is simply an exercise in metaphysics (41). While this view may seem extreme, major climatic shifts often recur at time intervals shorter than that required for a community to reach competitive equilibrium or alter the geographical distributions of species (6, 21, 43, 76, 92). Climatic variation of this kind influences ecological patterns over large areas, sometimes encompassing entire continents. Other agents of temporal change in natural communities operate over a wide range of smaller spatial scales (47, 242). Second, natural communities are spatially heterogeneous. This statement is true at any scale of resolution (242), but it is especially apparent on what is commonly referred to as the regional scale. (By region I mean an area that potentially encompasses more than one colonizable patch.) Across any land or seascape, one observes a mosaic of patches identified by spatial discontinuities in the distributions of populations (153, 159, 161, 231, 239, 240). Closer examination often reveals a smaller-scale patchwork of same-aged individuals (e.g. 85-87, 101, 146, 199,204,217-220,235,246). Discrete patch boundaries sometimes reflect species-specific responses to
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01 Sep 2011
TL;DR: In this paper, the Ecosystem Concept is used to describe the Earth's Climate System and Geology and Soils, and the ecosystem concept is used for managing and sustaining ecosystems.
Abstract: I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References
3,086 citations
Cites background from "The Role of Disturbance in Natural ..."
...Landscape-scale disturbance by fire, wind, floods, insect outbreaks, and hurricanes is a critical determinant of the natural structure and process rates in ecosystems (Pickett and White 1985, Sousa 1985)....
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TL;DR: The natural disturbance regime is now unlikely to persist within conser- vation area since fragmentation and human intervention have usually modified physical and biotic conditionx Active management decisions must now be made on what distur- bance regime is require and this requires decisions on what species are to be encouraged or discouraged.
Abstract: Preservation of natural communities has historically consisted of measures protecting them from physical disturbance. Timber harvests and livestock grazing are usually excluded from preserves, and fire suppression has been practiced—within the U.S. system of national parks, for example. Ecologists and conservationists have come to recognize, however, that many forms of disturbance are important components of natural systems. Many plant communities and species are dependent on disturbance, especially for regeneration (Pickett & White 1985). Preserves should be large enough to allow the natural disturbance regime to operate and to support a mosaic of patches in different stages of disturbance, successional recovery, and community maturation (Pickett & Thompson 1978).
2,370 citations
Book•
29 May 2006TL;DR: Reynolds as discussed by the authors provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity.
Abstract: Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.
1,856 citations
TL;DR: In this paper, the authors define disturbance in stream ecosystems to be: any relatively discrete event in time that is characterized by a frequency, intensity, and severity outside a predictable range, and that disrupts ecosystem, community, or population structure and changes resources or the physical environment.
Abstract: We define disturbance in stream ecosystems to be: any relatively discrete event in time that is characterized by a frequency, intensity, and severity outside a predictable range, and that disrupts ecosystem, community, or population structure and changes resources or the physical environment. Of the three major hypotheses relating disturbance to lotic community structure, the dynamic equilibrium hypothesis appears to be generally applicable, although specific studies support the intermediate disturbance hypothesis and the equilibrium model. Differences in disturbance frequency between lentic and lotic systems may explain why biotic interactions are more apparent in lakes than in streams. Responses to both natural and anthropogenic disturbances vary regionally, as illustrated by examples from the mid-continent, Pacific northwest, and southeastern United States. Based on a generalized framework of climatic-biogeochemical characteristics, two features are considered to be most significant in choosing streams...
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TL;DR: The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community as mentioned in this paper.
Abstract: The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained.
7,795 citations
Book•
01 Jan 1953
TL;DR: This book discusses the role of energy in Ecological Systems, its role in ecosystem development, and its implications for future generations of ecologists.
Abstract: Preface. Eugene P. Odum and Gary W. Barrett. 1. The Scope of Ecology. 2. The Ecosystem. 3. Energy in Ecological Systems. 4. Biogeochemical Cycles. 5. Limiting and Regulatory Factors. 6. Population Ecology. 7. Community Ecology. 8. Ecosystem Development. 9. Landscape Ecology. 10. Regional Ecology: Major Ecosystem Types and Biomes. 11. Global Ecology. 12. Statistical Thinking for Students of Ecology. Glossary. References. Index.
6,230 citations
TL;DR: In the majority of natural communities succession is frequently interrupted by major disturbances, such as fires, storms, insect plagues, etc., starting the process all over again, but if not interrupted, it eventually reaches a stage in which further change is on a small scale as individuals die and are replaced.
Abstract: The sequence of species observed after a relatively large space is opened up is a consequence of the following mechanisms. "Opportunist" species with broad dispersal powers and rapid growth to maturity usually arrive first and occupy empty space. These species cannot invade and grow in the presence of adults of their own or other species. Several alternative mechanisms may then determine which species replace these early occupants. Three models of such mechanisms have been proposed. The first "facilitation" model suggests that the entry and growth of the later species is dependent upon the earlier species "preparing the ground"; only after this can later species colonize. Evidence in support of this model applies mainly to certain primary successions and in heterotrophic succession. A second "tolerance" model suggests that a predictable sequence is produced by the existence of species that have evolved different strategies for exploiting resources. Later species will be those able to tolerate lower levels...
4,068 citations