Disentangling the effects of multiple environmental drivers on population changes within communities

Area of Science:

• Ecology
• Environmental Science
• Conservation Biology

Background:

• Environmental drivers like climate change and land-use change often impact species populations simultaneously, making it challenging to disentangle their effects.
• Statistical models incorporating environmental variables or species attributes are used to assess driver impacts, but these approaches are often applied separately or not compared.

Purpose of the Study:

• To compare the relative importance of climate change and agricultural land-use change on Danish terrestrial bird community abundance.
• To demonstrate the complementary insights gained by applying both environmental variable and species attribute-based modeling approaches.

Main Methods:

• Fitted population models to species' annual abundance data from 1983-2013.
• Included predictors such as species' temperature/habitat preferences and environmental variables (climate, land-use change).
• Analyzed relationships between species abundances and environmental variables/species attributes to identify drivers of community-level and interspecific abundance changes.

Main Results:

• Warmer winters and warm-adapted species showed positive abundance changes; agricultural land-use negatively impacted community abundance.
• Habitat specialists and birds using meadows experienced more negative abundance changes.
• Environmental variables had larger effect sizes for land-use change, while species attributes had larger effect sizes for climate change.

Conclusions:

• Agricultural land-use change decreased average species abundances, affecting total community size.
• Climate change influenced variation in abundance among species, impacting community composition.
• Integrating environmental variables and species attributes provides a more comprehensive understanding of driver impacts on ecological communities.