川西亚高山_高山森林土壤养分动态及其对季节性冻融的响应.docVIP

  川西亚高山/高山森林土壤养分动态及其对 季节性冻融的响应# 谭波，吴福忠，杨万勤** 5 10 15 （四川农业大学生态林业研究所，长江上游林业生态工程重点实验室，成都温江 611130） 摘要：季节性冻融是亚高山/高山地区普遍存在的气候现象。为了解川西亚高山/高山森林冬 季土壤生态过程，于 2008 年 11 月—2009 年 10 月，在土壤初冻期、冻结期和融化期及生长 季节，研究了不同海拔(3582 m、3298 m 和 3023 m )岷江冷杉林的土壤养分动态及其对季节 性冻融的响应。三个海拔森林土壤冬季具有较高的可溶性碳和氮、铵态氮、硝态氮含量。土 壤养分动态随土壤冻融过程不断变化。土壤有机层可溶性碳和氮、铵态氮、硝态氮含量随初 冻期土壤冻结过程显著增加后快速降低，随土壤融化迅速增加至完全融化后再次降低，而在 冻结期土壤可溶性碳和氮、硝态氮含量变化不明显，铵态氮显著增加。矿质土壤层可溶性碳 和氮、铵态氮含量同样在初冻期显著增加后降低，而土壤冻结后可溶性氮、铵态氮和硝态氮 显著增加，并在融化期经历一个明显的含量高峰。海拔和土层的交互作用显著影响了土壤可 溶性碳和硝态氮含量，但对可溶性氮和铵态氮含量不显著，土壤养分与土壤温度的相关性随 海拔差异而不同。这表明季节性冻融期是土壤生态过程的重要时期，土壤冻融格局显著影响 了土壤养分过程。 关键词：亚高山/高山森林; 季节性冻融; 土壤养分; 冬季生态学 中图分类号：S718.5 20 Dynamics of soil nutrients and their response to seasonal freeze–thaw in the subalpine/alpine forests of western Sichuan TAN Bo, WU Fuzhong, YANG Wanqin 25 30 35 40 (Key Laboratory of Ecological Forestry Engineering, Institute of Ecological Forestry, Sichuan Agricultural University, Wenjiang, Sichuan 611130, China) Abstract: Seasonal freeze–thaw in the subalpine/alpine region is a common climate phenomenon. In order to understand soil nutrients dynamics and their responses to seasonal freeze–thaw cycle in the subalpine/alpine forests of western Sichuan, three fir (Abies faxoniana) forests, including primary fir forest at 3582 m of altitude, fir and birch mixed forest at 3298 m of altitude, and secondary fir forest at 3023 m of altitude, were selected covering a 600 m vertical transition zone. Soils were sampled in different stages as the onset of soil freezing period, soil frozen period, soil thawing period and growing period from November 2008 to October 2009. The dissolve carbon and nitrogen, NH4+-N and NO3--N were measured. Soils in the sampled forests had relatively high dissolve carbon and nitrogen, NH4+-N and NO3--N in winter. The dynamics of measured soil nutrients changed with the process of soil freeze-thaw. In the soil organic layer, the dissolve carbon and nitrogen, NH4+-N and NO3--N experienced a significantly increasing then de