科尔沁沙地不同恢复方式下生态系统营养元素积累与分配特征

Nutrient elements' accumulation and distribution pattern of different grassland restoration approaches in Horqin Sandy Land

生态系统营养元素的生物地球化学循环是生态系统重要功能之一,正确认识不同恢复模式生态系统营养物质的积累和分配对生态恢复、项目实施与评估具有重要作用.对科尔沁沙地4种恢复方式下的生态系统营养元素积累与分配特征进行了研究,结果表明:3种树种各器官N、P、K含量排序整体上为叶>枝>根>干,N、K的积累排序为北京杨>榆树>樟子松,P的积累为樟子松>北京杨>榆树;不同恢复方式草本层地上部分N、P、K的积累均高于地下部分的积累;不同恢复方式乔木层N、P、K积累为0.233~0.292,0.074~0.098 t/hm^2和0.244~0.379 t/hm^2,草本层为0.023~0.049,0.003~0.008 t/hm^2和0.024~0.048 t/hm^2,凋落物层为0.006~0.008,0.001~0.002 t/hm^2和0.001~0.004 t/hm^2,土壤层为2.489~25.682,0.786~2.438 t/hm^2和44.749~98.465 t/hm^2;土壤层N、P、K的积累占总积累量的比例最大,分别为97.54%~98.81%,94.52%~99.49%和99.54%~99.94%,其次是乔木层,草本层,凋落物层最小;4种恢复方式下生态系统N、P、K营养元素的积累排序均为榆树疏林草地>樟子松疏林草地>防护林围草地>撂荒草地.研究结果表明:科尔沁沙地东南缘营造防护林和稀疏植树显著恢复了沙地植被,对生态系统N、P、K的积累与分配有显著影响,是较适合于科尔沁东南缘降水不足和土壤有效营养元素缺乏的植被恢复模式.

Biogeochemical cycle of nutrient elements is one of the most important ecosystem functions. Understanding the accumulation and distribution of nutrient elements in different restoration models plays an important role in ecological restoration,project implementation and assessment.The accumulation and distributions of nutrient elements under different grassland restoration approaches in Horqin Sandy Land was studied. The results sbowed：N,P and K concentration of various organs in three tree species ranked as follow：leaf〉branch〉root〉 trunk, as a whole, N and K accumulation of the three species ranked as follow： Peking Aspen〉Pinus sylvestris var. mongolica〉Ulmus pumila,P accumulation of three species tree ranked as follow：Pinus sylvestris var.mongolica 〉 Peking Aspen〉Ulmus pumila.Accumulation of N,P and K of aboveground parts of herb layer was higher than that of the underground parts despite the different restoration approaches.The accumulation of N, P and K in soil layer was the highest, followed by tree layer, herb layer and litter layer. N, P, K accumulation under four different grass- land restoration approaches was elm scattered grassland〉Mongolian Pine scattered grassland〉grassland fenced by shelter forest〉abandoned grassland, which showed that the recovery mode had a significant impact on the accumulation and distribution of N,P and K.The results also showed that shelterbelt and sparse planting in sand land in the southeast Horqin Sandy Land restored vegetation significantly and had a significant influence on the accumulation and distribution of N, P, and K, which was suggested to be more suitable for the vegetation restoration under insufficient precipitation and lack of available nutrient elements in the Southeast Horqin.