Eissenstat David M, Kucharski Joshua M, Zadworny Marcin, Adams Thomas S, Koide Roger T
Intercollege Graduate Degree Program in Plant Biology, Penn State University, University Park, PA, 16802, USA.
Department of Ecosystem Science and Management, Penn State University, University Park, PA, 16802, USA.
New Phytol. 2015 Oct;208(1):114-24. doi: 10.1111/nph.13451. Epub 2015 May 13.
The identification of plant functional traits that can be linked to ecosystem processes is of wide interest, especially for predicting vegetational responses to climate change. Root diameter of the finest absorptive roots may be one plant trait that has wide significance. Do species with relatively thick absorptive roots forage in nutrient-rich patches differently from species with relatively fine absorptive roots? We measured traits related to nutrient foraging (root morphology and architecture, root proliferation, and mycorrhizal colonization) across six coexisting arbuscular mycorrhizal (AM) temperate tree species with and without nutrient addition. Root traits such as root diameter and specific root length were highly correlated with root branching intensity, with thin-root species having higher branching intensity than thick-root species. In both fertilized and unfertilized soil, species with thin absorptive roots and high branching intensity showed much greater root length and mass proliferation but lower mycorrhizal colonization than species with thick absorptive roots. Across all species, fertilization led to increased root proliferation and reduced mycorrhizal colonization. These results suggest that thin-root species forage more by root proliferation, whereas thick-root species forage more by mycorrhizal fungi. In mineral nutrient-rich patches, AM trees seem to forage more by proliferating roots than by mycorrhizal fungi.
确定能够与生态系统过程相关联的植物功能性状备受关注，尤其是在预测植被对气候变化的响应方面。最细吸收根的根直径可能是一个具有广泛意义的植物性状。具有相对较粗吸收根的物种与具有相对较细吸收根的物种在营养丰富斑块中的觅食方式是否不同？我们测量了六种共存的丛枝菌根（AM）温带树种在添加和不添加养分情况下与养分觅食相关的性状（根形态和结构、根增殖以及菌根定殖）。根直径和比根长等根性状与根分支强度高度相关，细根物种的分支强度高于粗根物种。在施肥和未施肥的土壤中，具有细吸收根和高分支强度的物种比具有粗吸收根的物种表现出更大的根长度和质量增殖，但菌根定殖率更低。在所有物种中，施肥导致根增殖增加和菌根定殖减少。这些结果表明，细根物种更多地通过根增殖觅食，而粗根物种更多地通过菌根真菌觅食。在富含矿质养分的斑块中，AM树木似乎更多地通过根增殖而非菌根真菌觅食。
