Bell-Dereske Lukas, Takacs-Vesbach Cristina, Kivlin Stephanie N, Emery Sarah M, Rudgers Jennifer A
Department of Biology, 1 University of New Mexico, Albuquerque, NM 87131, USA.
FEMS Microbiol Ecol. 2017 Jun 1;93(6). doi: 10.1093/femsec/fix036.
Understanding interactions between above- and belowground components of ecosystems is an important next step in community ecology. These interactions may be fundamental to predicting ecological responses to global change because indirect effects occurring through altered species interactions can outweigh or interact with the direct effects of environmental drivers. In a multiyear field experiment (2010-2015), we tested how experimental addition of a mutualistic leaf endophyte (Epichloë amarillans) associated with American beachgrass (Ammophila breviligulata) interacted with an altered precipitation regime (±30%) to affect the belowground microbial community. Epichloë addition increased host root biomass at the plot scale, but reduced the length of extraradical arbuscular mycorrhizal (AM) fungal hyphae in the soil. Under ambient precipitation alone, the addition of Epichloë increased root biomass per aboveground tiller and reduced the diversity of AM fungi in A. breviligulata roots. Furthermore, with Epichloë added, the diversity of root-associated bacteria declined with higher soil moisture, whereas in its absence, bacterial diversity increased with higher soil moisture. Thus, the aboveground fungal mutualist not only altered the abundance and composition of belowground microbial communities but also affected how belowground communities responded to climate, suggesting that aboveground microbes have potential for cascading influences on community dynamics and ecosystem processes that occur belowground.
了解生态系统地上和地下组分之间的相互作用是群落生态学的重要下一步。这些相互作用对于预测生态系统对全球变化的响应可能至关重要，因为通过改变物种相互作用而产生的间接影响可能超过环境驱动因素的直接影响或与之相互作用。在一项为期多年的田间试验（2010 - 2015年）中，我们测试了与美国海滩草（Ammophila breviligulata）相关的互利叶内生菌（Epichloë amarillans）的实验添加如何与改变的降水模式（±30%）相互作用，以影响地下微生物群落。添加Epichloë在样地尺度上增加了宿主根系生物量，但减少了土壤中根外丛枝菌根（AM）真菌菌丝的长度。仅在正常降水条件下，添加Epichloë增加了每个地上分蘖的根系生物量，并降低了短叶沙鞭（A. breviligulata）根系中AM真菌的多样性。此外，添加Epichloë后，根系相关细菌的多样性随着土壤湿度的增加而下降，而在没有Epichloë的情况下，细菌多样性随着土壤湿度的增加而增加。因此，地上真菌共生体不仅改变了地下微生物群落的丰度和组成，还影响了地下群落对气候的响应，这表明地上微生物有可能对地下发生的群落动态和生态系统过程产生级联影响。
