论文部分内容阅读
细根对氮沉降的生理生态响应将显著影响森林生态系统的生产力和碳吸存。为了揭示氮沉降对杉木细根的生理生态影响,对一年生杉木(Cunninghamia lanceolata)幼苗进行了模拟氮沉降试验,并测定施氮1年后杉木幼苗细根生物量、细根形态学特征(比根长、比表面积)、元素化学计量学指标(C、N、P、C/N、C/P、N/P)、细根代谢特征(细根比呼吸速率、非结构性碳水化合物)。结果表明:(1)杉木细根生物量随氮添加水平的升高而显著降低,尤其是0—1 mm细根生物量;细根比根长和比表面积随氮添加水平升高而显著增大。(2)氮添加后杉木细根C含量、C/N、C/P显著降低,高氮添加导致1—2 mm细根N含量和N/P显著升高,而低氮添加导致1—2 mm细根P含量显著升高、N/P显著降低,而0—1 mm细根的N、P含量则保持相对稳定。(3)氮添加后杉木细根比呼吸速率无显著变化,细根可溶性糖含量随氮添加增加而显著增加,而淀粉含量和NSC显著降低。综合以上结果表明:氮添加后用于细根形态构建的碳分配减少,这可能会减少土壤中有机碳的保留,0—1 mm细根的形态更易发生变化,但是其内部N、P养分含量相对更稳定以维持生理活动,细根NSC对氮添加的响应表明施氮可能导致细根受光合产物的限制。
Physiological and ecological responses of fine roots to nitrogen deposition will significantly affect forest ecosystem productivity and carbon sequestration. In order to reveal the physiological and ecological effects of nitrogen deposition on the fine roots of Cunninghamia lanceolata, simulated nitrogen deposition experiments were conducted and the fine root biomass and fine root morphology of Chinese fir seedlings after 1 year of nitrogen application Long and specific surface area), elemental chemometrics (C, N, P, C / N, C / P, N / P), fine root metabolism (fine root specific respiration rate, unstructured carbohydrate). The results showed that: (1) The fine root biomass of Chinese fir decreased significantly with the increase of N addition, especially the fine root biomass of 0-1 mm. The root length and specific surface area of fine roots were significantly increased with the increase of N addition Big. (2) The content of C, C / N and C / P of Chinese fir decreased significantly after nitrogen addition. High nitrogen addition resulted in significant increase of 1-2 mm fine root N and N / P, The content of fine root P increased significantly while the N / P decreased significantly, while the content of N and P in fine root of 0-1 mm remained relatively stable. (3) There was no significant change in the specific root respiration rate of the Chinese fir after nitrogen addition. The soluble sugar content of fine roots increased significantly with the increase of nitrogen addition, while the starch content and NSC decreased significantly. Based on the above results, it is concluded that the allocation of carbon for fine root morphology after nitrogen addition decreases, which may reduce the retention of organic carbon in soil. The fine root morphology of 0-1 mm is more likely to change, but the content of N and P nutrients Relatively more stable to maintain physiological activity, responses of fine root NSCs to nitrogen addition indicate that application of nitrogen may result in the fine roots being limited by photosynthetic products.