As organisms shift their geographic distributions in response to climate change, biotic interactions have emerged as an important factor driving the rate and success of range expansions. Plant-microbe interactions are an understudied but potentially important factor governing plant range shifts. We studied the distribution and function of microbes present in high-elevation unvegetated soils, areas that plants are colonizing as climate warms, snow melts earlier and the summer growing season lengthens. Using a manipulative snowpack and microbial inoculation transplant experiment, we tested the hypothesis that growing season length and microbial community composition interact to control plant elevational range shifts. We predicted that a lengthening growing season combined with dispersal to patches of soils with more mutualistic microbes and fewer pathogenic microbes would facilitate plant survival and growth in previously unvegetated areas. We identified negative effects on survival of the common alpine bunchgrass Deschampsia cespitosa in both short and long growing seasons, suggesting an optimal growing season length for plant survival in this system that balances time for growth with soil moisture levels. Importantly, growing season length and microbes interacted to affect plant survival and growth, such that microbial community composition increased in importance in suboptimal growing season lengths. Further, plants grown with microbes from unvegetated soils grew as well or better than plants grown with microbes from vegetated soils. These results suggest that the rate and spatial extent of plant colonization of unvegetated soils in mountainous areas experiencing climate change could depend on both growing season length and soil microbial community composition, with microbes potentially playing more important roles as growing seasons lengthen.

中文翻译：

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生长季节长度和土壤微生物影响多才多艺的丛生草的性能超出其当前范围

随着生物体为响应气候变化而改变其地理分布，生物相互作用已成为推动范围扩展速度和成功的重要因素。植物与微生物的相互作用是一个尚未得到充分研究但可能影响植物范围变化的重要因素。我们研究了高海拔无植被土壤中存在的微生物的分布和功能，随着气候变暖，植物在这些地区定居，积雪较早融化，夏季生长季节延长。使用操纵性积雪和微生物接种移植实验，我们测试了生长季节长度和微生物群落组成相互作用以控制植物海拔范围变化的假设。我们预测，延长的生长季节与分散到具有更多共生微生物和更少致病微生物的土壤斑块相结合，将促进植物在以前没有植被的地区存活和生长。我们确定了对普通高山束草 cespitosa 在短期和长期生长季节中的存活的负面影响，表明该系统中植物存活的最佳生长季节长度可以平衡生长时间与土壤水分水平。重要的是，生长季节长度和微生物相互作用以影响植物的存活和生长，因此微生物群落组成在次优生长季节长度中的重要性增加。此外，用来自无植被土壤的微生物生长的植物与用来自植被土壤的微生物生长的植物一样好或更好。