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Permanent Plot Data (permanent + plot_data)

Distribution by Scientific Domains

Life Sciences	50%
Earth and Environmental Science	50%

Selected Abstracts

Invasion impacts local species turnover in a successional system

ECOLOGY LETTERS, Issue 9 2004
Kathryn A. Yurkonis
Abstract Exotic plant invasions are often associated with declines in diversity within invaded communities. However, few studies have examined the local community dynamics underlying these impacts. Changes in species richness associated with plant invasions must occur through local changes in extinction and/or colonization rates within the community. We used long-term, permanent plot data to evaluate the impacts of the exotic vine Lonicera japonica. Over time, species richness declined with increasing L. japonica cover. L. japonica reduced local colonization rates but had no effect on extinction rates. Furthermore, we detected significant reductions in the immigration of individual species as invasion severity increased, showing that some species are more susceptible to invasion than others. These findings suggest that declines in species richness associated with L. japonica invasion resulted from effects on local colonization rates only and not through the competitive displacement of established species. [source]

Invasion impacts diversity through altered community dynamics

JOURNAL OF ECOLOGY, Issue 6 2005
KATHRYN A. YURKONIS
Summary 1Invading plant species often alter community structure, composition and, in some instances, reduce local diversity. However, the community dynamics underlying these impacts are relatively unknown. 2Declines in species richness with invasion may occur via displacement of resident species and/or reduction of seedling establishment by the invader. These two mechanisms differ in the demographic stage of the interaction. 3We document turnover dynamics using long-term permanent plot data to assess the mechanism(s) of invasion impacts of four exotic species on a mixed community of native and exotic species. These mechanisms were evaluated at both the neighbourhood (1-m2 plot) and population (individual species) scales. 4During invasion, species richness declined with increasing invader cover for three of the four invaders. All invaders reduced colonization rates, but had no effect on extinction rates at the neighbourhood scale. Populations differed in their susceptibility to invasion impacts, with significant reductions in colonization for 10 of 25 (40%) species and increases in extinction for only 4 of 29 (14%) species. 5At neighbourhood and population scales, influences of invasion on community dynamics were essentially the same for all invaders regardless of life-form. While individual resident species had some increase in extinction probability, community richness impacts were largely driven by colonization limitation. 6The consistency of invasion impacts across life-forms suggests establishment limitation as a general mechanism of invasion impact. This common causal mechanism should be explored in other systems to determine the extent of its generality. [source]

Seed size and response to rainfall patterns in annual grasslands: 16 years of permanent plot data

JOURNAL OF VEGETATION SCIENCE, Issue 1 2009
B. Peco
Abstract Question: Are seed size and plant size linked to species responses to inter-annual variations in rainfall and rainfall distribution during the growing season in annual grasslands? Location: A 16-year data set on species abundance in permanent plots 15 km north of Madrid in a Quercus ilex subsp. ballota dehesa. Methods: At species level, a GLM was used to analyse the effects of various rainfall indices (total autumn rainfall, early autumn rainfall and spring drought) on species abundance residuals with respect to time and topography. We also assessed the importance of seed size and plant size in the species responses at community level using species as data points. Seed mass and maximum stem length were used as surrogates for seed size and plant size, respectively. Results: Seed mass and plant size may explain some of the fluctuations in the floristic composition of annual species associated with autumn rainfall patterns. Species that are more abundant in dry autumns have greater seed mass than those species that are more abundant in wet autumns. Early autumn rainfall seems to favour larger plants. Conclusions: Our empirical results support the hypothesis that autumn rainfall patterns affect the relative establishment capacity of small and large seedlings in annual species. [source]

On a level field: the utility of studying native and non-native species in successional systems

APPLIED VEGETATION SCIENCE, Issue 1 2009
Scott J. Meiners
Abstract Questions: How do successional systems contribute to our understanding of plant invasions? Why is a community-level approach important in understanding invasion? Do native and non-native plant species differ in their successional trajectories within communities? Location: Northeastern United States, in the Piedmont region of New Jersey. Previously farmed since the 1700s, ten fields were experimentally retired from agriculture beginning in 1958. Methods: Fifty years of permanent plot data were used to quantify the population demographics of the 84 most abundant species during succession. These measures were then used to compare native, non-native and non-native invasive species' population dynamics in succession. Results: Once basic life-history characteristics were accounted for, there were no differences in the population dynamics of native, non-native, and non-native invasive plant species. However, the species pool in this study was biased towards ruderal species, which largely constrained non-native species to early succession. Conclusion: Successional systems are crucial to our understanding of invasions as they constrain all species to the role of colonizer. By focusing on the whole community, rather than on individual problematic species, we found no systematic differences between native and non-native species. Thus, knowing simple life-history information about a species would be much more useful in setting management priorities than where the species originated. [source]