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- Reitalu, Triin, et al.
(författare)
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Plant species segregation on different spatial scales in semi-natural grasslands
- 2008
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Ingår i: Journal of Vegetation Science. - : John Wiley & Sons. - 1100-9233 .- 1654-1103. ; 19:3, s. 407-416
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Tidskriftsartikel (refereegranskat)abstract
- Question: We studied the patterns of plant species co-occurrence on three, nested, spatial scales in semi-natural grassland communities and explored the possible ecological processes underlying the patterns. Location: Dry, semi-natural grasslands in a 4.5 km x 4.5 km area on the Baltic Island of Oland (Sweden). Methods: The study used replicated samples on three, nested, spatial scales: 50 cm x 50 cm plots (N= 516), grassland patches (N = 109) and the whole landscape (N= 6). We used a null model approach to study species co-occurrence patterns and compared the ecological amplitudes of the pairs of species contributing most to the patterns. We used linear models to search for associations between species segregation and environmental and landscape factors. Results and Conclusions: Our results support the prediction that patterns of species co-occurrence are likely to be influenced by different mechanisms on different spatial scales. On the plot scale, we interpreted the species segregation in terms of species interactions. The degree of species segregation was significantly associated with the plots'positions within the grassland patches (edge effects) and with management intensity of the grasslands - both variables can be assumed to influence species interactions. On the grassland patch scale, we interpreted the species segregation in terms of within-patch environmental heterogeneity. The degree of segregation was significantly associated with the area of the grassland patches and with management intensity - both variables that are likely to be related to environmental heterogeneity within the grasslands. Species segregation on the landscape scale was interpreted in terms of environmental heterogeneity among grassland patches and was significantly associated with land-use history
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| 2. |
- Reitalu, Triin, et al.
(författare)
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Small-scale plant species richness and evenness in semi-natural grasslands respond differently to habitat fragmentation
- 2009
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Ingår i: Biological Conservation. - : Elsevier BV. - 1873-2917 .- 0006-3207. ; 142:4, s. 899-908
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Tidskriftsartikel (refereegranskat)abstract
- The study explores whether small-scale species diversity, species evenness and species richness in semi-natural grassland communities are similarly associated with present management regime and/or present and historical landscape context (percentage of different land-cover types in the surroundings). Species diversity, evenness and richness were recorded within 44150 x 50 cm grassland plots in a 4.5 x 4.5 km agricultural landscape on bland, Sweden. Recent and historical land-cover maps (years 2004, 1959, 1938, 1835, and 1800) were used to characterize the present and past landscape context of the sampled vegetation plots. Partial regression and simultaneous autoregressive models were used to explore the relationships between species diversity measures (Shannon diversity, richness and evenness) and different explanatory variables while accounting for spatial autocorrelation in the data. The results indicated that species richness was relatively sensitive to grassland isolation, while the response of species evenness to isolation was characterized by a degree of inertia. Because the richness and evenness components of species diversity may respond differently to habitat fragmentation, we suggest that monitoring projects and empirical studies that focus on changes in biodiversity in semi-natural grasslands should include the assessment of species evenness - as a complement to the assessment of species richness. In addition, our results indicated that the development and persistence of a species-rich and even grassland vegetation was favoured in areas that have historically (in the 19th century) been surrounded by grasslands. Information on landscape history should, whenever possible, be incorporated into the planning of strategies for grassland conservation. (C) 2008 Elsevier Ltd. All rights reserved.
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