增温及隔离降雨对杉木不同序级细根形态和化学计量学性状的影响

Effects of Soil Warming and Precipitation Exclusion on the Morphological and Stoichiometric Traitsof Fine Roots of Different Orders in Cunninghamia lanceolata

为了解细根形态和化学计量学性状对增温和干旱交互作用的响应。在福建三明森林生态系统国家野外科学观测研究站开展杉木Cunninghamia lanceolata幼苗增温(不增温和增温5℃)×隔离降雨(不隔离降雨和隔离降雨50%)双因子试验,共4个处理,即对照(CT)、土壤增温(W)、隔离降雨(P)、增温+隔离降雨(WP)。在处理1年后,测定前3序级细根的形态和化学计量学性状。结果表明:增温和隔离降雨对细根形态性状均无显著交互作用。增温主效应对细根直径(RD)无显著影响,但显著降低细根比根长(SRL,特别是1序级根)和细根比表面积(SRA)、显著增加细根组织密度(RTD);隔离降雨主效应仅显著降低了SRL,而对RD、SRA和RTD均无显著影响。增温和隔离降雨以及两者交互作用显著影响细根碳(C)、氮(N)含量以及碳氮比(C∶N)。与CT相比,P处理导致1和2序级细根C含量和C∶N显著降低,而N含量显著升高;W和WP处理下各序级细根N含量显著上升,而细根C∶N显著降低。在增温和隔离降雨作用下,细根可能增强了生理吸收能力(高N含量),但却弱化了养分的探寻能力(低SRL和SRA)。研究结果有助于深入理解全球气候变化背景下亚热带地区杉木细根应对环境应力的生态策略。

In order to understand the responses of fine root morphological and stoichiometric traits to the interaction of warming and drought,the two-factor experiment of soil warming(no warming and 5℃warming)and precipitation exclusion(no precipitation exclusion and 50%precipitation exclusion)with Cunninghamia lanceolata seedlings as the materials was carried out in the National Field Scientific Observation and Research Station of Forest Ecosystem in Sanming of Fujian.There were four treatments,namely the control group(CT),soil warming(W),precipitation exclusion(P),and soil warming+precipitation exclusion(WP).The morphological and stoichiometric traits of fine roots in the first three orders were measured after one year of treatment.The results showed that there was no significant interaction between temperature enhancement and precipitation exclusion on the morphological traits of fine roots.The main effect of temperature enhancement had no significant effect on the diameter of fine roots(RD),but significantly reduced the specific root length of fine roots(SRL,especially the first-order root)and the specific surface area of fine roots(SRA),while significantly increased the fine root tissue density(RTD).The main effect of precipitation exclusion only significantly reduced the specific root length(SRL),but had no significant effect on the root diameter(RD),specific surface area(SRA)and root tissue density(RTD).The effect of temperature enhancement,precipitation exclusion and their interactions had significant effects on the contents of carbon and nitrogen in fine roots and the carbon-nitrogen ratio.Compared with CT,the P treatment resulted in a significant decrease in carbon content and carbon-nitrogen ratio of fine roots in first and second order.The nitrogen content of fine roots in each order increased significantly under W and WP treatments,while the carbon-nitrogen ratio of fine roots decreased significantly.Under the effect of temperature enhancement and precipitation exclusion,the fine roots of Cunninghamia lanceolata may enhance the physiological absorption ability(high content of nitrogen),but weaken the ability to explore nutrients(low SRL and SRA).The results of this study were helpful to further understand the ecological strategies of the fine roots of Cunninghamia lanceolata to cope with the environmental stress in the subtropical regions in the context of global climate change.