Long-term climate sensitivity of grazer performance: a cross-site study

Area of Science:

• Ecology and Environmental Science
• Climate Change Impacts
• Animal Science

Background:

• Grasslands are vital ecosystems supporting numerous grazers.
• Climate change presents complex challenges to grassland environments and grazer populations.
• Predicting the effects of altered climate on grazer performance is crucial for ecological and economic stability.

Purpose of the Study:

• To investigate the consequences of a warmer, drier climate on grazer performance using bison as a model.
• To analyze bison body mass data in relation to climate patterns and variability.
• To project potential economic impacts on cattle production under future climate scenarios.

Main Methods:

• Compiled a large dataset of over 250,000 bison weights from 22 US herds across diverse climates.
• Analyzed bison body mass patterns concerning geographic climate variations and interannual climate fluctuations.
• Correlated climate variables (temperature, precipitation) with bison performance metrics.

Main Results:

• Short-term climate variability effects on grazers depend on precipitation timing and amount.
• Sustained hotter, drier conditions negatively impact grazers primarily through reduced forage quality.
• Long-term higher temperatures are linked to declining grassland nitrogen availability and forage quality, affecting bison performance.

Conclusions:

• While short-term temperature increases show minimal impact, sustained warming poses significant long-term risks to grazers.
• Reduced forage quality due to climate change is a key driver of negative grazer performance.
• Potential economic losses for US cattle could reach $1 billion per 1°C temperature increase, highlighting the need for monitoring.