Jiang Lei, Wang Huimin, Li Shenggong, Fu Xiaoli, Dai Xiaoqin, Yan Han, Kou Liang
Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
New Phytol. 2021 Jan;229(1):284-295. doi: 10.1111/nph.16844. Epub 2020 Sep 1.
Traits are critical in predicting decomposition that fuels carbon and nutrient cycling in ecosystems. However, our understanding of root trait-decomposition linkage, and especially its dependence on mycorrhizal type and environmental context, remains limited. We explored the control of morphological and chemical (carbon- and nutrient-related) traits over decomposition of absorptive roots in 30 tree species associated with either arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi in temperate and subtropical forests in China. Carbon-related traits (acid-unhydrolysable residue (AUR) and cellulose concentrations) had predominant control of root decomposition in AM species while nutrient-related traits (magnesium concentration) predominately controlled that in ECM species. Thicker absorptive roots decomposed faster in AM species as a result of their lower AUR concentrations, but more slowly in ECM angiosperm species potentially as a result of their higher magnesium concentrations. Root decomposition was linked to root nutrient economy in both forests while root diameter-decomposition coordination emerged only in the subtropical forest where root diameter and decomposition presented similar cross-species variations. Our findings suggest that root trait-decomposition linkages differ strongly with mycorrhizal type and environment, and that root diameter can predict decomposition but in opposing directions and with contrasting mechanisms for AM and ECM species.
植物性状对于预测生态系统中推动碳和养分循环的分解过程至关重要。然而，我们对根系性状与分解之间的联系，尤其是其对菌根类型和环境背景的依赖性，仍然了解有限。我们在中国温带和亚热带森林中，研究了与丛枝菌根（AM）或外生菌根（ECM）真菌相关的30种树木的吸收根的形态和化学（与碳和养分相关）性状对其分解的控制作用。与碳相关的性状（酸不溶性残渣（AUR）和纤维素浓度）对AM树种的根系分解起主要控制作用，而与养分相关的性状（镁浓度）对外生菌根树种的根系分解起主要控制作用。由于AUR浓度较低，AM树种中较粗的吸收根分解得更快，但在ECM被子植物树种中分解得更慢，这可能是由于它们的镁浓度较高。在这两种森林中，根系分解都与根系养分经济有关，而根系直径与分解的协调性仅出现在亚热带森林中，在那里根系直径和分解呈现出相似的跨物种变化。我们的研究结果表明，根系性状与分解之间的联系因菌根类型和环境的不同而有很大差异，并且根系直径可以预测分解，但对AM和ECM树种来说方向相反且机制不同。
