摘要
对 1 962年以来采集的表层土壤和深层土壤样品进行培养实验 ,以研究退耕还林 40年来土壤氮的动态变化以及植被恢复对土壤氮库矿质化的影响 .供试土样在专门设计的矿质化培养系统中 ,以温度 30℃、通气并保持土壤湿度的条件下培养 30d ,以 2mol LKCl溶液浸提培养土并测定其氮含量 .结果表明 ,土壤矿质氮及全氮含量均在造林的头 2 0年迅速下降 ,在 2 0年的林木生长过程中 ,生物吸收积累了土壤中约 80 %— 90 %的有效氮 ,表明耕地中施入的氮对树木早期生长有着重要作用 ;树龄达 40年时 ,土壤原有矿质氮的 5 0 %— 80 %已返还土壤 .这一结果表明 ,森林地被已成为土壤营养的重要来源 ,并且森林生态系统提供的这种有机质可成为可持续利用的土壤氮资源 .
Soil samples archived over four decades were used in an incubation experiment to measure the effects of reforestation on nitrogen dynamics in old agricultural fields. Samples collected from depths 0 cm to 7 5 cm and 35 cm to 60 cm at intervals ranging between five and nine years since 1962 were incubated aerobically at 30℃ for 30 days using a system specially designed to maintain constant soil moisture. Mineral N was measured in 2 mol/L KCl extracts. The ratio of mineralized N to total N rapidly decreased in the first two decades of forest development. Within 20 years of planting, 80% to 90% of plant available N had accumulated in the biomass indicating that agricultural inputs of N were important to early tree development. Significantly, by age 40, 50% to 80% of the original pool of mineral N had returned to the soil profile. The accretion of mineralizable N suggests that forest floor is serving as an increasingly important source for this nutrient. Further, it indicates that forest managers have the opportunity to manipulate a large pool of forest organic matter to sustain soil N supply.
出处
《中国科学院研究生院学报》
CAS
CSCD
2004年第2期241-247,共7页
Journal of the Graduate School of the Chinese Academy of Sciences
基金
SupportedbyYunnanEducationFoundationforstudyingabroad ,andGrantsfromUSDANationalResearchInitiativeandUSNSFtoDukeUniversity
关键词
植被恢复地
土壤
培养
氮矿质化
氮库
动态变化
长期
reforested soils, incubation, N-mineralization, nitrogen dynamics, long-term
