Nonlinear shifts in infectious rust disease due to climate change

Range shifts of infectious plant disease are expected under climate change. As plant diseases move, emergent abiotic-biotic interactions are predicted to modify their distributions, leading to unexpected changes in disease risk. Evidence of these complex range shifts due to climate change, however, remains largely speculative. Here, we combine a long-term study of the infectious tree disease, white pine blister rust, with a six-year field assessment of drought-disease interactions in the southern Sierra Nevada. We find that climate change between 1996 and 2016 moved the climate optimum of the disease into higher elevations. The nonlinear climate change-disease relationship contributed to an estimated 5.5 (4.4-6.6) percentage points (p.p.) decline in disease prevalence in arid regions and an estimated 6.8 (5.8-7.9) p.p. increase in colder regions. Though climate change likely expanded the suitable area for blister rust by 777.9 (1.0-1392.9) km(2) into previously inhospitable regions, the combination of host-pathogen and drought-disease interactions contributed to a substantial decrease (32.79%) in mean disease prevalence between surveys. Specifically, declining alternate host abundance suppressed infection probabilities at high elevations, even as climatic conditions became more suitable. Further, drought-disease interactions varied in strength and direction across an aridity gradient-likely decreasing infection risk at low elevations while simultaneously increasing infection risk at high elevations. These results highlight the critical role of aridity in modifying host-pathogen-drought interactions. Variation in aridity across topographic gradients can strongly mediate plant disease range shifts in response to climate change. Climate change is expected to have major impacts on forest tree diseases. Here the authors analyse long-term data of white pine blister rust in the southern Sierra Nevada, finding evidence of climate change-driven disease range expansion that was mediated by spatially varying host-pathogen-drought interactions.

Automated summary

Climate change driven shifts in the distribution of white pine blister rust were observed in this study, with the disease's climate optimum moving to higher elevations from 1996 to 2016. The study also highlighted the important role of host-pathogen-drought interactions in modifying disease prevalence, contributing to changes in infection risk at different elevations. Variations in aridity across different topographic gradients were found to strongly mediate plant disease range shifts in response to climate change.