文献类型：会议论文

英文题名：NITROGEN CYCLING AND DYNAMIC ANALYSIS OF MAN-MADE LARCH FOREST ECOSYSTEM

作者：LIU, SR

机构：[1]CHINESE ACAD FORESTRY, FORESTRY RES INST, BEIJING 100091, PEOPLES R CHINA

会议论文集：International Symposium on Nutrient Uptake and Cycling in Forest Ecosystems

会议日期：JUN 07-10, 1993

会议地点：HALMSTAD, SWEDEN

语种：英文

外文关键词：DECOMPOSITION; DYNAMIC CHANGE; LARCH FOREST; MINOR VEGETATION; NITROGEN CYCLING; SIMULATION MODEL; UPTAKE

年份：1995

摘要：Nitrogen cycling process and dynamic change over 2 years were studied in 21-year-old planted dahurian larch (Lurir gmelinii (Rupr) Rupr.) in the eastern part of northern China. N concentrations in the plants varied by tissue, age, position in tree and season, In the aboveground components the N concentration was highest in foliage, followed by live branches, bolebark and bolewood. The organic N concentrations in undergrowth and herbs were higher than that in larch tree. The total amount of N accumulated in the larch ecosystem was 13167 kg.ha(-1), in which the percentages of N storage in soil, living plants, dead standing and litter were 94.7%, 2.8%, 0.1% and 2.4%, respectively. The uptake of N by vegetation was 56 kg.ha(-1).y(-1), in which the retention acid return were 24 kg,ha(-1).y(-1) and 32 kg.ha(-1) y(-1), respectively. Precipitation provided 13 kg.ha(-1).y(-1) of N, while N loss via runoff was 4 kg.ha(-1).y(-1) and therefore, the net gain of N by ecosystem was 9 kg.ha(-1).y(-1). The simulation of N dynamic change showed that an increase in the age of stand was accompanied by a concomitant increase in N storage in the forest floor, whereas N flux from forest floor organic matter into soil would decrease, and consequently, growth rate of larch stands would reduce owing to the inadequacy of available N in the soil. The prediction indicated that the degradation of soil fertility in larch plantation might occur under continuous cropping. The study implied that release rate of N from litter into soil was the key factor in determining and regulating N cycling in larch plantation. The understory minor vegetation in the larch stand plays an important role in speeding up N cycling. The timely thinning is needed to improve growth and development of shrubs and herbs, and to avert the potential soil degradation. The mixed stand of larch with either a certain proportion of broad-leaved species or a moderately well developed understory vegetation should be encouraged.