Assessing ecological responses to environmental change using statistical models
Article first published online: 22 NOV 2007
© 2007 The Authors
Journal of Applied Ecology
Volume 45, Issue 1, pages 193–203, February 2008
How to Cite
Ferguson, C. A., Carvalho, L., Scott, E. M., Bowman, A. W. and Kirika, A. (2008), Assessing ecological responses to environmental change using statistical models. Journal of Applied Ecology, 45: 193–203. doi: 10.1111/j.1365-2664.2007.01428.x
- Issue published online: 22 NOV 2007
- Article first published online: 22 NOV 2007
- Received 19 December 2006; accepted 14 September 2007; Handling Editor: Rosie Hails
- climate change;
- Loch Leven;
- statistical model;
- 1There is a clear need to improve our ability to assess the ecological consequences of environmental change. Because of the complexity of ecosystems and a need to disentangle the effects of multiple pressures, predictions are often reliant on models and expert opinion. These require validation with observed data; in this respect, long-term data sets are particularly valuable.
- 2Innovative statistical methods (nonparametric regression and additive models) are presented for identifying nonparametric ecological trends and changes in seasonality in response to environmental change. These are illustrated through the example of Loch Leven, a shallow freshwater lake. Monitoring data for 35 years are examined, spanning periods of enrichment, ecological recovery and changing climate.
- 3Models are developed for phosphorus and nitrogen; temperature and rainfall; Daphnia grazers; and chlorophyll a, with the ecological objectives of examining trends in water quality and the corresponding trends in nutrient availability, grazer abundance and climate.
- 4The analysis highlighted a generally decreasing availability of P over the study period, and generally increasing nonparametric trends in nitrate concentration and rainfall. Increasing spring temperatures were also evident, as were significant nonparametric changes in density of summer grazers.
- 5Significant reductions are highlighted in spring and summer chlorophyll a, related to the return of Daphnia to the loch. However, no response in chorophyll a to the later declining trends in P is apparent, but seasonality has changed.
- 6Synthesis and applications. The analysis highlights the value of nonparametric statistical models for assessing complex ecological responses to environmental change. The models outlined can examine key ecological impacts of climate change, particularly effects on the timing of seasonal events and processes. The models are illustrated using long-term water-quality data from Loch Leven to explore patterns in key environmental drivers and ecological responses affecting freshwater ecosystems. Analysis of chlorophyll a, in particular, highlighted the value of examining the seasonal trends separately, with different trends evident for winter and spring and a changing seasonal pattern.