| 1. |
- Clark, Adam Thomas, et al.
(författare)
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General statistical scaling laws for stability in ecological systems
- 2021
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 24:7, s. 1474-1486
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Tidskriftsartikel (refereegranskat)abstract
- Ecological stability refers to a family of concepts used to describe how systems of interacting species vary through time and respond to disturbances. Because observed ecological stability depends on sampling scales and environmental context, it is notoriously difficult to compare measurements across sites and systems. Here, we apply stochastic dynamical systems theory to derive general statistical scaling relationships across time, space, and ecological level of organisation for three fundamental stability aspects: resilience, resistance, and invariance. These relationships can be calibrated using random or representative samples measured at individual scales, and projected to predict average stability at other scales across a wide range of contexts. Moreover deviations between observed vs. extrapolated scaling relationships can reveal information about unobserved heterogeneity across time, space, or species. We anticipate that these methods will be useful for cross-study synthesis of stability data, extrapolating measurements to unobserved scales, and identifying underlying causes and consequences of heterogeneity.
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| 2. |
- Olofsson, Johan, et al.
(författare)
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Contrasting effects of rabbit exclusion on nutrient availability and primary production in grasslands at different time scales
- 2007
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 150, s. 582-589
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Tidskriftsartikel (refereegranskat)abstract
- Herbivores influence nutrient cycling and primary production in terrestrial plant communities. However, both empirical and theoretical studies have indicated that the mechanisms by which herbivores influence nutrient availability, and thus their net effects on primary production, might differ between time scales. For a grassland in southeast England, we show that the effects of rabbits on primary production change over time in a set of grazed plots paired with exclosures ranging from 0 to 14 years in age. Herbivore exclusion decreased net aboveground primary production (APP) in the short term, but increased APP in the long term. APP was closely correlated with N mineralization rates in both grazed and ungrazed treatments, and accumulation of litter within the grazing exclosures led to higher N mineralization rates in exclosures in the long run. Rabbit grazing did not influence litter quality. The low contrast in palatability between species and the presence of grazing-tolerant plants might prevent rabbits from favoring unpalatable plant species that decompose slowly, in contrast to results from other ecosystems. Our results indicate that it is essential to understand the effects on N cycling in order to predict the effect of rabbit grazing on APP. Rabbits might decrease N mineralization and APP in the long term by increasing losses of N from grasslands.
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