马尾松人工林林窗土壤有效氮和氮转化酶活性的季节动态  

Seasonal variations of soil available nitrogen and nitrogen transformation enzyme activities in forest gaps of Pinus massoniana plantations

作　　者：李建平[1] 欧江[1,2] 宋小艳[1] 邓长春[1] 张艳[1] 张健[1] 高顺[1] 

机构地区：[1]四川农业大学生态林业研究所/四川生态林业工程重点实验室,成都611130 [2]四川省资阳市林业局,四川资阳641300

出　　处：《生态学杂志》2015年第9期2598-2604,共7页Chinese Journal of Ecology

基　　金：国家科技支撑计划项目(2011BAC09B05);国家自然科学基金项目(31370628);四川省科技支撑计划项目(12ZC0017);教育部博士点基金项目(20135103120001)资助

摘　　要：对长江上游低山丘陵区马尾松人工林4种不同大小林窗（G1：100 m2、G2：400 m2、G3：900 m2、G4：1600 m2）及林下土壤铵态氮、硝态氮、脲酶及亚硝酸还原酶活性进行季节动态对比分析。结果表明,随着林窗面积增大,铵态氮呈先升后降的趋势,硝态氮呈现降低的趋势,铵态氮、硝态氮、脲酶活性分别在400 m2、100~400 m2、900~1600 m2的林窗较高,亚硝酸还原酶活性在面积为400 m2的林窗较低,说明林窗面积对铵态氮和硝态氮有显著影响,小林窗更利于土壤中有效氮的积累。铵态氮春季显著高于其他三季,硝态氮、脲酶活性秋冬两季较高,亚硝酸还原酶活性秋季较高。与林下相比,有效氮仅小林窗在春夏季明显升高;酶活性总体较林下高,但无明显差异,仅林窗边缘的亚硝酸还原酶活性显著高于中央。此外,土壤有效氮、酶活性与土壤温度、含水量密切相关。林窗形成后,对微气候条件尤其是土壤湿度的改善,可能提高土壤酶活,进而促进土壤氮的转化。The seasonal variations of ammonium nitrogen（ NH4＋-N）,nitrate nitrogen（ NO3--N）,activities of urease and nitrite reductase in different-sized forest gaps（ G1： 100 m2,G2：400 m2,G3： 900 m2,G4： 1600 m2） of Pinus massoniana plantations in hilly area of the upper reaches of the Yangtze River were analyzed. Our results showed that the ammonium nitrogen content gradually increased,and then decreased with the increasing size of forest gap,while the nitrate nitrogen content showed a decrease trend. The NH4＋-N,NO3--N contents,and urease activity of soil were higher in the forest gaps of 400 m2,100-400 m2 and 900-1600 m2 than in the other gaps. However,the nitrite reductase activity in the forest gap of 400 m2 was lower than in the other gaps. These findings indicated that the NH4＋-N and NO3--N contents were significantly affected by forest gap size,and smaller size of forest gaps contributed to soil nitrogen mineralization. The NH4＋-N content in spring was significantly higher than in other seasons,and the content of NO3--N and urease activity were higher in autumn and winter. However,the nitrite reductase activity was highest in autumn. Compared to under tree canopy,the available nitrogen content in smaller forest gaps significantly increased in spring and summer; the enzyme activity was higher but no significant differences were observed except that the nitrite reductase activity in the gap edge was significantly higher than in the center of forest gap. Moreover,the available nitrogen content and enzyme activity were closely related to soil temperature and moisture. Our findings suggested that after the formation of gaps,the improvement of soil moisture may enhance the enzyme activity and further contribute to the transformation of nitrogen in soil.

关 键 词：马尾松人工林 林窗 铵态氮 硝态氮 脲酶 亚硝酸还原酶 

分 类 号：S791.248[农业科学—林木遗传育种]