Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80309-0334, USA.
Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, 80309-0450, USA.
Ecology. 2020 Sep;101(9):e03095. doi: 10.1002/ecy.3095. Epub 2020 Jun 9.
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.
随着生物对气候变化而改变其地理分布，生物相互作用已成为驱动范围扩展速度和成功率的一个重要因素。植物-微生物相互作用是一个研究不足但可能对植物范围转移具有重要意义的因素。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，这些土壤是随着气候变暖、雪融得更早和夏季生长季节延长而被植物殖民的地区。我们使用了一种可操作的雪堆和微生物接种移植实验，测试了这样一个假设，即生长季节长度和微生物群落组成相互作用，以控制植物的海拔范围转移。我们预测，生长季节的延长加上向具有更多互利微生物和更少致病微生物的土壤斑块的扩散，将促进植物在以前无植被地区的生存和生长。我们发现，在短和长的生长季节中，对常见高山丛生草 Deschampsia cespitosa 的生存都有负面影响，这表明在这个系统中，植物生存的最佳生长季节长度在平衡生长时间和土壤水分水平方面存在平衡。重要的是，生长季节长度和微生物相互作用会影响植物的生存和生长，使得在生长季节不理想的情况下，微生物群落组成变得更加重要。此外，用无植被土壤中的微生物培养的植物的生长情况与用植被土壤中的微生物培养的植物的生长情况一样好或更好。这些结果表明，在经历气候变化的山区，无植被土壤中植物的殖民化速度和空间范围可能取决于生长季节长度和土壤微生物群落组成，随着生长季节的延长，微生物可能会发挥更重要的作用。
