Data from: Differences in thallus chemistry are related to species-specific effects of biocrust-forming lichens on soil nutrients and microbial communities

1. It is well-known that vascular plants have species-specific effects on soil properties. However, little is known on how individual species forming biocrusts, communities dominated by lichens, mosses and cyanobacteria that are prevalent in many ecosystems world-wide, affect microbial communities and soil variables related to nutrient cycling. 2. We evaluated the relationship of six biocrust-forming lichens (Buellia epipolia, Diploschistes diacapsis, Fulgensia subbracteata, Psora decipiens, Squamarina cartilaginea and Squamarina lentigera) with microbial abundance and multiple variables associated with soil nitrogen (N), carbon (C) and phosphorus (P) cycling and storage. We also evaluated whether the composition of lichen tissues (contents in C, N, P and polyphenols) is related to the C, N, P availability and microbial abundance in soils. Finally, we assessed what lichen species positively and negatively relate to soil fertility compared to bare ground areas without biocrusts. 3. We found contrasted C, N, P availability and soil microbial abundance under the different biocrust-forming lichens. Interestingly, inorganic P and amino acids were the most important factors differentiating lichen microsites. These differences in nutrient availability seem to be related to the C, N and P composition of the lichen tissues. For example, soils under D. diacapsis and P. decipiens, which had the lowest and highest C, N and P contents in their tissues, respectively, had the lowest and highest nutrient availability, respectively. We also found contrasted soil microbes abundance under the different soil lichens. For instance, F. subbracteata and D. diacapsis were negatively related to the abundance of bacteria compared to bare ground areas. 4. Our results support the idea that, as found with vascular plants, biocrust-forming lichens have species-specific effects on soil microbial communities and C, N and P cycling. Thus, continuing considering biocrusts as a unique entity will only add confusion to our knowledge of how they control nutrient availability and microbial abundance in the ecosystems where this key community is prevalent.

1. 众所周知，维管植物会对土壤性质产生物种特异性的影响。然而，对于由地衣、苔藓和蓝细菌主导、在全球众多生态系统中广泛分布的生物结皮（biocrusts）群落而言，单个物种如何影响微生物群落以及与养分循环相关的土壤变量，目前仍知之甚少。
2. 本研究评估了6种形成生物结皮的地衣——粉斑饼衣（Buellia epipolia）、双盘孢属地衣（Diploschistes diacapsis）、亮叶网衣（Fulgensia subbracteata）、白粉炮仗衣（Psora decipiens）、软骨鳞叶衣（Squamarina cartilaginea）及薄鳞叶衣（Squamarina lentigera）——与微生物丰度，以及与土壤碳（C）、氮（N）、磷（P）循环和储存相关的多项变量之间的关联。此外，我们还评估了地衣组织的组成（即碳、氮、磷及多酚含量）是否与土壤中的碳、氮、磷有效性及微生物丰度相关。最后，我们对比了有生物结皮的区域与无生物结皮的裸地，明确了哪些地衣物种与土壤肥力呈正相关或负相关。
3. 我们发现，不同生物结皮地衣对应的土壤碳、氮、磷有效性及微生物丰度存在显著差异。值得注意的是，无机磷与氨基酸是区分各地衣微生境的最关键因子。这类养分有效性的差异似乎与地衣组织的碳、氮、磷组成相关。例如，组织碳、氮、磷含量分别最低和最高的双盘孢属地衣与白粉炮仗衣，其对应土壤的养分有效性也分别最低和最高。同时，不同地衣覆盖下的土壤微生物丰度也存在显著差异：相较于裸地，亮叶网衣与双盘孢属地衣的存在与细菌丰度呈负相关。
4. 本研究结果证实，与维管植物的情况一致，形成生物结皮的地衣对土壤微生物群落及碳、氮、磷循环具有物种特异性的影响。因此，若继续将生物结皮视为一个统一的整体，只会混淆我们对这类关键群落如何调控其广泛分布生态系统中养分有效性与微生物丰度的认知。