Oxalate Biogeochemistry of Forest Soil Ectomycorrhizal Mat Communities

Drs。Griffiths, Caldwell， Baham和Cromack已经表明，某些特殊的外生菌根物种的Gautieria和Hysterangium形成广泛的菌丝或根状垫结构，这是温带针叶林的显著特征。与没有明显垫地发育的土壤相比，两种类型的垫地均提高了孔隙水中溶解有机碳、氟化物、草酸盐和硫酸盐的浓度，以及主要和微量金属阳离子，包括Al和Fe，它们可以控制有机磷和无机磷的溶解度。在海地草垫中，大部分草酸盐以固相形式存在，可能是草酸钙，而在豪蒂尔草垫中，相对较大比例的草酸盐以溶液形式存在，其浓度接近土壤有机质提取中使用的浓度。草酸盐的配体性质虽然长期与矿物溶解有关，但也表明草酸盐在森林土壤过程中起着其他重要作用。Drs。Griffiths, Caldwell， Baham和Cromack将利用这些垫子群落来研究草酸盐物种和其他主要有机配体在矿物风化，溶液和固相土壤化学，Al和Fe活性以及不同森林生态型土壤酶对有机氮和磷的处理中的作用。实地研究和实验室实验的结果将被用作输入土壤溶液和固相生物地球化学的准稳态模型。该模型将为森林生态系统中控制养分循环的实际机制提供洞见。这些研究人员是森林土壤生物地球化学领域的专家。可用于这项研究的设备是非常出色的。

Drs. Griffiths, Caldwell, Baham and Cromack have shown that certain specialized ectomycorrhizal species of Gautieria and Hysterangium form extensive hyphal or rhizomorph mat structures that are significant features of temperate coniferous forests. In comparison with soils without obvious mat development, both types of mats have elevated pore-water concentrations of dissolved organic carbon, fluoride, oxalate, and sulfate, as well as major and trace metal cations, including Al and Fe which can be responsible for controlling the solubility of both organic and inorganic phosphorus. In Hysterangium mats, most of the oxalate was present in the solid phase, presumably as calcium oxalate, while in Gautieria mats, a relatively larger fraction of oxalate was in solution at concentrations that approached those used in organic matter extractions of soils. While long implicated in mineral dissolution, the ligand properties of oxalate also suggest other significant roles in forest soil processes. Drs. Griffiths, Caldwell, Baham and Cromack will use these mat communities to investigate the role of oxalate species and other major organic ligands in mineral weathering, solution and solid phase soil chemistry, Al and Fe activity, and the processing of organic nitrogen and phosphorus by soil enzymes in diverse forest ecotypes. Results from field studies and laboratory experiments will be used as input to a quasi-steady-state model of soil solution and solid phase biogeochemistry. This model will provide insight into actual mechanisms controlling nutrient cycling in forest ecosystems. These researchers are experts in the area of forest soil biogeochemistry. The facilities available for this research are outstanding.