Long-term grazing effects on soil-borne pathogens are driven by temperature.

Abstract

Soils support a highly diverse community of plant pathogens, which are highly responsive to global change. Climate and livestock grazing are the main global changes in grasslands, yet, how long-term grazing alone, and in interaction with climate, influence the distribution of soil-borne plant pathogens remain virtually unknown. Here, we present the first long-term regional-scale experimental investigation on the impacts of livestock grazing on soil-borne fungal plant pathogens and their association with plant community across 10 experimental sites spanning a climate gradient in the steppe in Northern China. Our results showed that long-term grazing effects on the diversity and proportion of soil-borne fungal plant pathogens are strongly controlled by temperature, with grazing increasing pathogen richness and proportions largely in cooler grasslands. We further show that long-term grazing supported stronger connections between soil-borne fungal pathogens and plant communities. Our work demonstrates that climate controls the effects of grazing on plant pathogens, which is critical to understand and manage grasslands in a changing world.