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研究了川西理县毕棚沟不同海拔梯度(3600 m、3300 m和3000 m)森林群落土壤活性氮库及土壤净氮矿化速率的季节动态.结果表明:研究区森林土壤活性氮库(铵态氮、硝态氮、微生物生物量氮和可溶性有机氮)及净氮矿化速率存在明显的季节变化,但不同形态土壤活性氮库的季节动态有一定差异.4个采样时期(非生长季与生长季初期、中期及末期)各海拔土壤硝态氮浓度(8.38~89.60 mg·kg-1)均显著高于铵态氮浓度(0.44~8.43 mg·kg-1).生长季初期各海拔梯度的土壤净氮矿化速率均表现为负值(-0.77~-0.56 mg·kg-1·d-1),而非生长季、生长季中期和末期均为正值.除硝态氮外,不同海拔的土壤铵态氮、微生物生物量氮和可溶性有机氮浓度的差异极显著,海拔对它们的影响与季节变化有关.该区土壤净氮矿化以硝化为主,且氮矿化过程不受海拔梯度的影响.冬季土壤净氮矿化明显(0.42~0.99 mg·kg-1·d-1),早春高的土壤无机氮可能为植物生长提供基础养分,也可能通过淋溶方式从系统中丢失.
The seasonal dynamics of soil active nitrogen pool and net nitrogen mineralization rate of forest communities with different altitudes (3600 m, 3300 m and 3000 m) in Bengshenggou, Lixian County, western Sichuan were studied. The results showed that: There was a significant seasonal variation in the rate of mineralization of nitrogen, nitrogen, nitrate nitrogen, microbial biomass nitrogen and soluble organic nitrogen and the net nitrogen mineralization rate, but there were some differences in seasonal dynamics of soil active nitrogen pools. (8.38-89.60 mg · kg-1) were significantly higher than those of ammonium nitrogen (0.44- 8.43 mg · kg-1) at the beginning, middle and last growing season, The net nitrogen mineralization rate of the gradient soil showed negative values (-0.77-0.56 mg · kg-1 · d-1), but not in the growing season, both in the middle and the end of the growing season. , The differences of soil ammonium nitrogen, microbial biomass nitrogen and soluble organic nitrogen at different altitudes were extremely significant.The effects of altitude on them were related to the seasonal changes.The net nitrogen mineralization in this area was dominated by nitrification and the nitrogen mineralization Unaffected by the altitude gradient, net soil nitrogen mineralization was significant in winter (0.42-0.99 mg · kg -1 · d -1), high soil inorganic N in early spring may provide basic nutrients for plant growth, and may also be lost from the system by leaching.