Widespread slowdown in short-term species turnover despite accelerating climate change

Area of Science:

• Ecology
• Environmental Science
• Biodiversity Research

Background:

• Ecological communities undergo changes in species composition over time, termed temporal species turnover.
• Environmental drivers are commonly cited as the cause of these changes.
• However, intrinsic ecosystem dynamics can also drive temporal species turnover, even in stable environments.

Purpose of the Study:

• To investigate the relative contributions of environmental drivers versus intrinsic ecosystem dynamics to observed temporal species turnover.
• To analyze trends in species turnover over the last century using a global database.

Main Methods:

• Analysis of the BioTIME database, a global collection of ecological survey data.
• Examination of temporal species turnover rates over short time intervals (1-5 years) across numerous communities.
• Comparison of observed turnover trends with predictions based on environmental change acceleration versus intrinsic dynamics.

Main Results:

• Contrary to expectations of accelerated turnover with climate change, species turnover has decelerated in a majority of communities over the last 100 years.
• This deceleration was significant, typically by one-third.
• The findings suggest intrinsic ecosystem dynamics are a dominant factor in many observed changes in species composition.

Conclusions:

• Observed changes in species composition may often be manifestations of natural, intrinsic ecosystem dynamics rather than solely environmental drivers.
• The deceleration of turnover could be linked to factors like anthropogenic environmental degradation or reduced regional species pools limiting colonizers.
• Attributing species turnover solely to environmental drivers requires caution, especially in the current context where intrinsic dynamics appear prevalent.