Because interactions between plants and microbial organisms can influence species diversity and rates of nutrient cycling, how plants shape microbial communities is fundamental to understanding the structure of ecosystems. Despite this, the spatial and temporal scales over which plants influence microbial communities is poorly understood, particularly whether past abiotic or biotic legacies strongly constrain microbial community development. We examined biogeochemical cycling and microbial community structure in a coastal landscape where historical patterns of vegetation transition after a large fire in 1995 are well known, allowing us to account for past abiotic and biotic conditions. We found that alternative states in microbial community structure and ecosystem processes emerged under different plant species, regardless of past conditions. Greenhouse studies further demonstrated that these differences arise from direct plant selection of microbes, with selection stronger in roots compared with soils, especially for bacteria. Correlation of microbial community structure with seedling growth rates was also stronger for fungi compared to bacteria. Despite these effects, minimal overlap between seedling and field microbial communities indicates that the effects of initial plant selection are not stable; rather, plant selection initiated alternative successional trajectories after the fire. Using data from a guild where we have abundant natural history information, ectomycorrhizal fungi, we show that greenhouse communities are dominated by ruderal taxa that are also common in the field after the fire and that these ruderal fungi strongly alter spatial patterns in plant–soil feedback, enabling invasion and transformation of soils previously occupied by heterospecific plants, thus potentially acting as keystone mutualists.

中文翻译：

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扰动后植物的选择在土壤微生物群落中启动了替代的演替轨迹

由于植物与微生物之间的相互作用会影响物种多样性和养分循环速率，因此植物如何塑造微生物群落是了解生态系统结构的基础。尽管如此，人们对植物影响微生物群落的时空尺度知之甚少，尤其是过去的非生物或生物遗产是否强烈限制了微生物群落的发展。我们研究了沿海景观的生物地球化学循环和微生物群落结构，该景观在1995年大火后植被转变的历史模式众所周知，这使我们能够解释过去的非生物和生物条件。我们发现，不管过去的条件如何，微生物群落结构和生态系统过程中的替代状态都在不同的植物物种下出现。温室研究进一步表明，这些差异源于微生物对植物的直接选择，与土壤相比，根系的选择更强，尤其是对细菌而言。与细菌相比，真菌的微生物群落结构与幼苗生长速率的相关性也更强。尽管有这些影响，但幼苗和田间微生物群落之间的最小重叠表明，初始植物选择的影响并不稳定。相反，大火过后，植物的选择引发了替代性的连续轨迹。利用我们拥有丰富自然历史信息的行会数据，即外生菌根真菌，我们可以证明温室群落以蒲类群为主，在火灾后该领域也很常见，这些蒲类真菌强烈改变了植物-土壤反馈的空间格局。 ，