Patterns of plant species diversity during succession under different disturbance regimes (original) (raw)
Related papers
Journal of Vegetation Science, 2008
AbstractQuestion: Does shifting cultivation contribute to plant diversity in an Afrotropical semi-deciduous forest lacking large-scale natural disturbance?Does shifting cultivation contribute to plant diversity in an Afrotropical semi-deciduous forest lacking large-scale natural disturbance?Location: Sanaimbo forest, Côte d'Ivoire (Ivory Coast).Sanaimbo forest, Côte d'Ivoire (Ivory Coast).Methods: We surveyed species assemblages, structural attributes of diversity, and life-history traits along a 30-year chronosequence of abandoned fields, comparatively to old-growth and selectively logged forest stands.We surveyed species assemblages, structural attributes of diversity, and life-history traits along a 30-year chronosequence of abandoned fields, comparatively to old-growth and selectively logged forest stands.Results: Patterns of species assemblages strongly changed with fallow area age, with respect to species'light requirements, suggesting niche partitioning along the successional gradient. Species richness, diversity and equitability were all increasing along this gradient. There were clear shifts in life-history traits spectra as the forest recovered, especially regarding leaf shape, lifespan and hairiness, diaspore dispersal, seed size, resprouting capacity, and life forms. Early colonization by the invasive Chromolaena odorata did not appear to impair secondary succession. Soil type influenced old-growth forest vegetation but not fallow vegetation. After 30 years of forest regrowth, plant communities exhibited endemism rates similar to those of ancient forests.Patterns of species assemblages strongly changed with fallow area age, with respect to species'light requirements, suggesting niche partitioning along the successional gradient. Species richness, diversity and equitability were all increasing along this gradient. There were clear shifts in life-history traits spectra as the forest recovered, especially regarding leaf shape, lifespan and hairiness, diaspore dispersal, seed size, resprouting capacity, and life forms. Early colonization by the invasive Chromolaena odorata did not appear to impair secondary succession. Soil type influenced old-growth forest vegetation but not fallow vegetation. After 30 years of forest regrowth, plant communities exhibited endemism rates similar to those of ancient forests.Conclusions: Shifting cultivation appears to be a sustainable land use when small-sized fields are embedded in a forest matrix and when agriculture lasts only one to few years, preserves remnant trees, excludes fire and keeps several years between two clearing episodes. It may even contribute to the high biodiversity maintenance at the whole forest scale, by conserving the successional mosaic. However, conservation of old-growth forest patches is required for a number of climax tree species.Shifting cultivation appears to be a sustainable land use when small-sized fields are embedded in a forest matrix and when agriculture lasts only one to few years, preserves remnant trees, excludes fire and keeps several years between two clearing episodes. It may even contribute to the high biodiversity maintenance at the whole forest scale, by conserving the successional mosaic. However, conservation of old-growth forest patches is required for a number of climax tree species.
Interaction of historical and nonhistorical disturbances maintains native plant communities
Ecological Applications, 2009
Historical disturbance regimes are often considered a critical element in maintaining native plant communities. However, the response of plant communities to disturbance may be fundamentally altered as a consequence of invasive plants, climate change, or prior disturbances. The appropriateness of historical disturbance patterns under modern conditions and the interactions among disturbances are issues that ecologists must address to protect and restore native plant communities. We evaluated the response of Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh plant communities to their historical disturbance regime compared to other disturbance regimes. The historical disturbance regime of these plant communities was periodic fires with minimal grazing by large herbivores. We also investigated the influence of prior disturbance (grazing) on the response of these communities to subsequent disturbance (burning). Treatments were: (1) ungrazed (livestock grazing excluded since 1936) and unburned, (2) grazed and unburned, (3) ungrazed and burned (burned in 1993), and (4) grazed and burned. The ungrazed-burned treatment emulated the historical disturbance regime. Vegetation cover, density, and biomass production were measured the 12th, 13th, and 14th year post-burning. Prior to burning the presence of Bromus tectorum L., an exotic annual grass, was minimal (,0.5% cover), and vegetation characteristics were similar between grazed and ungrazed treatments. However, litter accumulation was almost twofold greater in ungrazed than in grazed treatments. Longterm grazing exclusion followed by burning resulted in a substantial B. tectorum invasion, but burning the grazed areas did not produce an invasion. The ungrazed-burned treatment also had less perennial vegetation than other treatments. The accumulation of litter (fuel) in ungrazed treatments may have resulted in greater fire-induced mortality of perennial vegetation in ungrazed compared to grazed treatments. Our results demonstrate that prior disturbances exert a strong influence on the response of plant communities to subsequent disturbances and suggest that low-severity disturbances may be needed in some plant communities to increase their resilience to more severe disturbances. Modern deviations from historical conditions can alter ecosystem response to disturbances, thus restoring the historical disturbance regime may not be an appropriate strategy for all ecosystems.
Functional traits are supposed to play an important role in determining the colonization success of new species into established communities. short-term experimental studies have documented higher resistance of more diverse grasslands against colonization by new species. However, little is known about which traits colonizers should have to successfully invade diverse plant communities in the longer term and how community history may modify the resistance of diverse communities against colonization.
Ecosphere, 2018
Changes in species diversity following volcanic eruptions have been studied extensively, but our knowledge on functional diversity and community assembly under such conditions is very limited. Here, we study the processes following the destruction of vegetation after a volcanic eruption. Specifically, we investigate (1) the temporal patterns of taxonomic and functional diversity over time since a previous eruption (alpha diversity) and beta diversity, (2) the temporal patterns of 26 individual traits (vegetative characteristics, plant taxa ecological preferences, and regenerative characteristics) providing more detailed information on species strategies at the initial and later stages of succession, and (3) the processes driving species assembly and whether they changed over time since the eruption an eruption. We analyzed data recorded during five floristic censuses that took place between 1911 and 2011, calculated alpha and beta facets of taxonomic and functional diversity and exa...
Functional traits during succession: is plant community assembly trait-driven?
Little is known about changes in the significance of environmental filtering and neutral processes during the succession of plant communities. Generally, a succession is expected to be trait-driven and a shift is predicted from high importance of seed dispersal ability in initial phases to importance of strong competitive ability in later stages. In this study, we consider a community assembly traitdriven in the case of a shift in functional traits during succession and randomly assembled in the case there is no shift in functional traits during succession. We therefore tested whether urban plant communities show trait convergence or trait divergence in relation of successional stage, water and nutrient availability. At two scales (100 × 100 cm and 10 × 10 cm), we analysed traits relevant to seed dispersal, stress tolerance and competitive ability and compared real data with null models. We subsequently used regression trees to associate convergence and divergence to plot age and stress due to low water and soil nutrient availability. Most traits were neither significantly convergent nor divergent and the variance explained by the regression trees was often lower than 20%. We found divergence in seed number instead of the expected convergence towards high seed number. In accord with expectations we found low seed terminal velocity and annual life span in early succession. Convergence in seed bank longevity occurred at intermediate plot age, and convergence in the combination of life span and lateral spread showed the relevance of competition filtering in the most fertile plots. On the other hand, competition-induced convergence in canopy height or specific leaf area was not supported by our results. We concluded that, based on the traits considered in this study, the overwhelming evidence was that community assembly during the first 40 years of succession was driven by trait-neutral mechanisms.
Ecology, 2005
Secondary succession reflects, at least in part, community assembly-the sequences of colonizations and extinctions. These processes in turn are expected to be sensitive to the size of the site undergoing assembly and its location relative to source pools. In this paper we describe patterns of succession over 18 years in an experimentally fragmented landscape created in eastern Kansas, USA, in 1984. The design of the experiment permits one to assess the influence of patch size and landscape position on successional dynamics. The general trajectory of succession follows that typical of succession in much of the eastern United States. In the initial years of the study, there was relatively little effect of patch size or distance to sources. Here we show that spatial effects in this system have become increasingly evident with time, as gauged both by repeated-measures ANOVA and ordination techniques. Woody plants have colonized more rapidly (per unit area) on large and nearby patches. Species richness at a local (within-quadrat) scale in general has increased, with slightly greater richness in large than in small patches later in the study. Temporal stability in community composition has generally been greater in large patches. Spatial heterogeneity in community composition has increased during succession, but with different patterns in large and small patches. This long-term experiment suggests that landscape structure influences many aspects of community structure and dynamics during succession, and that such effects become more pronounced with the passage of time.
Disturbance effects on plant community diversity: spatial scales and dominance hierarchies
Vegetatio, 1991
It is proposed that evaluations of disturbance effects upon community diversity will be influenced by two factors currently overlooked in models addressing disturbance-diversity relationships: (1)the spatial scale of inquiry, and (2)the level of the species abundance (dominance) hierarchy at which the search for diversity is done. We analyzed how two disturbance types -cattle grazing and large flooding -affected community diversity at two spatial scales (stand and patch) and three levels of species dominance in a grassland of the Flooding Pampa, Argentina. The effect of disturbance interaction was also examined. Species diversity at the stand scale was reduced by either grazing or flooding. Both disturbances decreased community spatial heterogeneity. At the patch scale, diversity declined with flooding but was enhanced by grazing. Flooding increased diversity under grazing conditions. However, stand diversity was highest in the undisturbed grassland; pattern diversity was the salient feature in this condition. The combination of disturbances yielded the highest patch-scale diversity; grazing increased richness whilst flooding enhanced evenness. Comparisons among grassland conditions appeared scale-dependent. Moreover, the extent of disturbance effects varied with the level of dominance hierarchy considered. We point out the relevance of site history and initial conditions, encompassing the possibility of disturbances interaction, to the patterns produced by disturbance events. Effects perceived at different spatial scales, or in species positioned at separate dominance levels, may parallel meaningful changes in the relative importance of factors controlling species coexistence and community organization.
Journal of Ecology, 2014
1. Disturbance can function to maintain diversity within forest communities; however, specific mechanisms and the relationship to productivity are not well understood. 2. We examined these linkages in forest ground-layer plant communities using a replicated, manipulative field experiment. Treatments included a range of gap sizes and untreated controls. We assessed spatial and temporal responses over the first three years following gap creation. 3. Light transmittance and soil water content increased with gap size, while rates of colonization and species richness increased after a critical threshold. Subsequent increases in productivity were associated with declines in species richness, increased rates of local extirpation and a unimodal relationship between species richness and productivity at the individual quadrat scale (4 m 2 ). 4. The richness and productivity of vines, shrubs and especially graminoids, increased within 200-380 m 2 gaps treatments. However, the productivity of forbs and tree seedlings did not, showing possible drought sensitivity overriding treatments. Spatial and temporal partitioning of gaps occurred as a result of interactions between species traits and environmental conditions. Significantly, productivity and richness showed complex relationships with canopy structure. 5. Synthesis. Our results show that richness increases to an asymptote after a critical threshold in disturbance severity initially. Decreases in species richness over time associated with increases in productivity may eventually result in the unimodal relationship predicted by the intermediate disturbance hypothesis. However, species composition continues to differ with canopy gap size, suggesting a range of canopy gap sizes is required to maintain the greatest diversity of plant species over broader spatial and temporal scales.
1999
Mit dem Zugriff auf den vorliegenden Inhalt gelten die Nutzungsbedingungen als akzeptiert. Die ETH-Bibliothek ist Anbieterin der digitalisierten Zeitschriften. Sie besitzt keine Urheberrechte an den Inhalten der Zeitschriften. Die Rechte liegen in der Regel bei den Herausgebern. Die angebotenen Dokumente stehen für nicht-kommerzielle Zwecke in Lehre und Forschung sowie für die private Nutzung frei zur Verfügung. Einzelne Dateien oder Ausdrucke aus diesem Angebot können zusammen mit diesen Nutzungshinweisen und unter deren Einhaltung weitergegeben werden. Das Veröffentlichen von Bildern in Print-und Online-Publikationen ist nur mit vorheriger Genehmigung der Rechteinhaber erlaubt. Die Speicherung von Teilen des elektronischen Angebots auf anderen Servern bedarf ebenfalls des schriftlichen Einverständnisses der Rechteinhaber.