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Process-based long-term evaluation of an ecological network of calcareous grasslands

Wagner, Helene H. and Rico, Yessica and Lehnert, Henry and Boehmer, Hans J. (2013) Process-based long-term evaluation of an ecological network of calcareous grasslands. Ecography, 36 (3). pp. 374-382. ISSN 0906-7590

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This paper evaluates the long-term effect of an ecological network of calcareous grasslands, a habitat type that experienced dramatic habitat loss and fragmentation during the 20th century. Calcareous grasslands are of special conservation concern as the habitat type with the highest diversity in plant and invertebrate species in Central Europe. A baseline survey in 1989 established complete vascular plant species lists for all 62 previously abandoned calcareous grassland patches in the study area and assessed the presence of 48 habitat specialist plant species. An ecological network was initiated in 1989 to reconnect these patches with existing core areas through large flock sheep herding where feasible, as sheep are thought to be the primary dispersal vectors for calcareous grassland plants. An evaluation survey in 2009 showed significant increase in species richness of habitat specialist plants in patches reconnected by sheep herding, indicating successful colonizations by habitat specialist plant species, while ungrazed patches showed no significant change. Baseline species richness after abandonment was associated with patch area and vegetation type, suggesting that extinction delays depended on asymmetry of competition with later seral species, whereas subsequent increase in species richness was related to connectivity by sheep herding and the presence of a diversity of structural elements providing microsites for establishment. The implementation of this ecological network represents a long-term ‘natural experiment’ with baseline data, manipulation, and evaluation of hypothesized effects on a clearly defined target variable. It thus provides much needed empirical evidence that species loss in fragmented calcareous grassland communities can be counteracted by restoring functional connectivity among remnant patches.

Item Type: Journal Article
Uncontrolled Keywords: biodiversity; colonization; connectivity; extinction; fragmentation; Franconian Alb; Germany; grazing; habitat loss; natural experiment Files
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Geography, Earth Science and Environment
Depositing User: USP RSC Assistant
Date Deposited: 05 Oct 2017 04:28
Last Modified: 05 Oct 2017 04:28

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