Plant pathogens are important for ecosystem functioning and community assembly and respond to a variety of biotic and abiotic factors, which change along elevation gradients. Thus elevational gradients are a valuable model system for exploring how plant community, soil properties, and environmental factors influence pathogens. Yet, how these factors influence pathogens in nature remains poorly understood. We tested patterns and potential mechanisms of plant fungal pathogens along elevational gradients by combining a field survey in the Tibetan Plateau with a global meta-analysis. We found that increasing elevation was associated with a decrease in soil fungal pathogen richness but not foliar fungal disease symptoms. Elevation mainly related to soil fungal pathogen richness through abiotic factors. Whereas no evidence supported association between elevation and foliar fungal disease. The meta-analysis suggests some generality in the results of the field survey: elevation was associated with a decrease in soil fungal pathogen richness, but had no consistent relationship with foliar fungal disease or pathogens. Our study reveals distinct patterns of above- and belowground plant pathogen along elevation gradients and provides new insight into the potential mechanisms in shaping these patterns.

Attempts over the past 30 years to explain geographic variation in the strength of herbivore pressure gave rise to the latitudinal herbivory hypothesis. However, this long-standing hypothesis has rarely been tested using community-level data. In this study, we selected 43 grassland sites along a 1,500-km latitudinal gradient (c. 27°N to 39°N) on the Qinghai-Tibetan Plateau. We calculated community-wide herbivory at each site by summing herbivory across plant species weighted by the biomass of each species; we then investigated how abiotic and biotic latitudinal correlates drove community-wide herbivory via their effects on intraspecific herbivory variability and species’ turnover. We found that community-wide herbivory decreased with latitude, mirroring intraspecific herbivory variability. Furthermore, intraspecific herbivory variability was driven by climatic factors, but not edaphic or plant community factors. Overall, our study highlights the importance of considering both intraspecific herbivory variability and species’ turnover for predicting how climate change will alter community-wide herbivory.