Tuesday 6
Measuring complex changes in complex landscapes
Manuel Boissière, Douglas Sheil
› 15:45 - 16:40 (55min)
Similar resilience attributes in lakes with different management practices
Didier Baho  1@  
1 : Swedish University of Agricultural Sciences  (SLU)  -  Website
S-750 07 Uppsala -  Suède

Liming has been used extensively in Scandinavia and elsewhere since the 1970s to counteract the negative effects of acidification. Although the effects of liming on biological communities are well documented, it is unclear whether liming is able to break hysteresis in acidified lakes, to shift them to a state equivalent to pre-acidification conditions requiring no further intervention. In this study, we assessed community metrics (diversity, richness, evenness, biovolume), multivariate community structure and the relative resilience of phytoplankton in limed, acidified and circumneutral lakes from 1997 to 2009. We assessed two attributes of relative resilience (cross-scale and within-scale structure) of the phytoplankton communities using multivariate time series modeling. Liming increased phytoplankton diversity and richness; however, multivariate community structure differed in limed relative to acidified and circumneutral lakes. Cross-scale and within-scale attributes of resilience were similar across all lakes studied but the contribution of those species exhibiting stochastic dynamics was higher in the acidified and limed compared to circumneutral lakes. From a resilience perspective, our results suggest that limed lakes comprise a particular condition of an acidified lake state; that is, liming does not move lakes from a “degraded” basin of attraction, and thereby fails to break hysteresis. In addition from identifying the pathology of lake liming, our study demonstrates the potential of time series modeling to assess the efficiency of restoration and management outcomes through quantification of the attributes contributing to resilience in ecosystems.

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