Rosling Anna, Midgley Meghan G, Cheeke Tanya, Urbina Hector, Fransson Petra, Phillips Richard P
Department of Evolutionary Biology, EBC, Uppsala University, Uppsala, Sweden.
Biology Department, Indiana University, Bloomington, IN, 47405, USA.
New Phytol. 2016 Feb;209(3):1184-95. doi: 10.1111/nph.13720. Epub 2015 Oct 28.
Although much is known about how trees and their associated microbes influence nitrogen cycling in temperate forest soils, less is known about biotic controls over phosphorus (P) cycling. Given that mycorrhizal fungi are instrumental for P acquisition and that the two dominant associations - arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi - possess different strategies for acquiring P, we hypothesized that P cycling would differ in stands dominated by trees associated with AM vs ECM fungi. We quantified soil solution P, microbial biomass P, and sequentially extracted inorganic and organic P pools from May to November in plots dominated by trees forming either AM or ECM associations in south-central Indiana, USA. Overall, fungal communities in AM and ECM plots were functionally different and soils exhibited fundamental differences in P cycling. Organic forms of P were more available in ECM plots than in AM plots. Yet inorganic P decreased and organic P accumulated over the growing season in both ECM and AM plots, resulting in increasingly P-limited microbial biomass. Collectively, our results suggest that P cycling in hardwood forests is strongly influenced by biotic processes in soil and that these are driven by plant-associated fungal communities.
尽管人们对树木及其相关微生物如何影响温带森林土壤中的氮循环已经了解很多，但对于生物对磷（P）循环的控制作用却知之甚少。鉴于菌根真菌对磷的获取至关重要，且两种主要的共生关系——丛枝菌根（AM）真菌和外生菌根（ECM）真菌——具有不同的获取磷的策略，我们推测在以与AM真菌或ECM真菌相关的树木为主的林分中，磷循环会有所不同。我们在美国印第安纳州中南部，对由形成AM或ECM共生关系的树木主导的样地，从5月到11月对土壤溶液中的磷、微生物生物量磷以及依次提取的无机磷和有机磷库进行了量化。总体而言，AM和ECM样地中的真菌群落功能不同，土壤在磷循环方面表现出根本差异。ECM样地中有机磷的有效性高于AM样地。然而，在生长季节，ECM和AM样地中的无机磷均减少，有机磷均积累，导致微生物生物量的磷限制日益增加。总体而言，我们的结果表明，硬木森林中的磷循环受到土壤生物过程的强烈影响，而这些过程是由与植物相关的真菌群落驱动的。
