Soil P pools are strongly driven by microbial activities, and vice versa, P pools shape bacterial communities and their functional potential. Biological soil crusts (biocrusts) represent a microbial hotspot for nutrient turnover. We compared biocrusts and bulk soil samples from different temperate beech (Fagus sylvatica L.) forests representing a gradient in soil texture, nutrient concentrations, and pH values at biocrust peak biomass. We measured the total and plant-available P and N concentrations and assessed the bacterial potential to mineralize (phoD, phnX), solubilize (gcd), and take up P (pstS and pitA) and mineralize (chiA, apr) and fix N (nifH) by quantifying the respective marker genes (qPCR). We found an increase of absolute and relative bacterial abundance involved in P turnover in biocrusts, but the strategy to acquire P differed between the regions as bacteria harboring the starvation-induced pstS gene were most abundant where labile P was lowest. In contrast, the region with lowest total P concentrations has a higher potential to utilize more stable phosphonates. N mineralization was strongly correlated to P turnover at regions with increased labile N and P concentrations. Interestingly, the potential to fix N was highest in the bulk soil where total P concentrations were highest. Even though the correlation of N and P turnover is strongest if their ratio is low, the acquisition strategy strongly depends on soil properties.

中文翻译：

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德国温带森林生物土壤结皮中催化磷氮转化的细菌丰度的相关性

土壤磷池受到微生物活动的强烈驱动，反之亦然，磷池塑造细菌群落及其功能潜力。生物土壤结皮（生物结皮）代表了养分周转的微生物热点。我们比较了来自不同温带山毛榉 (Fagus sylvatica L.) 森林的生物结皮和大块土壤样品，它们代表了生物结皮峰值生物量下土壤质地、养分浓度和 pH 值的梯度。我们测量了总的和植物可利用的 P 和 N 浓度，并评估了细菌矿化（phoD、phnX）、溶解（gcd）和吸收 P（pstS 和 pitA）和矿化（chiA、apr）和固定 N 的潜力。 nifH) 通过量化相应的标记基因 (qPCR)。我们发现与生物结皮中磷周转有关的绝对和相对细菌丰度增加，但获取磷的策略因区域而异，因为携带饥饿诱导的 pstS 基因的细菌在不稳定磷最低的地方最为丰富。相比之下，总磷浓度最低的区域更有可能利用更稳定的膦酸盐。在不稳定的 N 和 P 浓度增加的区域，N 矿化与 P 周转密切相关。有趣的是，固定 N 的潜力在总 P 浓度最高的大块土壤中最高。即使 N 和 P 周转率的相关性在它们的比率低时最强，但获取策略在很大程度上取决于土壤特性。总磷浓度最低的区域更有可能利用更稳定的膦酸盐。在不稳定的 N 和 P 浓度增加的区域，N 矿化与 P 周转密切相关。有趣的是，固定 N 的潜力在总 P 浓度最高的大块土壤中最高。即使 N 和 P 周转率的相关性在它们的比率低时最强，但获取策略在很大程度上取决于土壤特性。总磷浓度最低的区域更有可能利用更稳定的膦酸盐。在不稳定的 N 和 P 浓度增加的区域，N 矿化与 P 周转密切相关。有趣的是，固定 N 的潜力在总 P 浓度最高的大块土壤中最高。即使 N 和 P 周转率的相关性在它们的比率低时最强，但获取策略在很大程度上取决于土壤特性。