冻融末期川西亚高山/高山森林土壤水解酶活性特征

Soil hydrolase characteristics in late soil-thawing period in subalpine/alpine forests of west Sichuan

冻融末期是连接冬季与生长季节的关键时期,期间强烈的温度变化可能深刻影响土壤生态过程.为了解冻融末期川西亚高山/高山森林土壤的生化过程,2009年3月5日—4月25日土壤融化期间,研究了该区典型冷杉原始林、针阔混交林和冷杉次生林土壤转化酶、脲酶和磷酸酶(中性、酸性和碱性磷酸酶)活性特征.结果表明:在土壤完全冻结期,3个森林群落各水解酶的活性仍相对较高.在土壤融化前期,随土壤温度升高,除中性磷酸酶外,其他水解酶活性均出现了一个爆发性增高然后迅速降低的过程.随后,除转化酶外,其他水解酶活性均随土壤温度的升高而持续增高.相对于矿质土壤层,冻融末期土壤有机层的水解酶活性更高,对土壤温度变化的响应更加明显.

Late soil-thawing period is a critical stage connecting winter and growth season.The significant temperature fluctuation at this stage might have strong effects on soil ecological processes.In order to understand the soil biochemical processes at this stage in the subalpine/alpine forests of west Sichuan,soil samples were collected from the representative forests including primary fir forest,fir and birch mixed forest,and secondary fir forest in March 5-April 25,2009,with the activities of soil invertase,urease,and phosphatase（neutral,acid and alkaline phosphatases） measured.In soil frozen period,the activities of the three enzymes in test forests still kept relatively higher.With the increase of soil temperature,the activities of hydrolases at the early stage of soilthawing decreased rapidly after a sharp increase,except for neutral phosphatease.Thereafter,there was an increase in the activities of urease and phosphatase.Relative to soil mineral layer,soil organic layer had higher hydrolase activity in late soil-thawing period,and showed more obvious responses to the variation of soil temperature.