论文部分内容阅读
为了解高山森林林窗对土壤氮动态的影响,于2012—2013年在川西高山冷杉原始林大、中、小林窗以及林下采集了4个关键时期(初冻期、深冻期、初融期和融化末期)的土样,测定其铵态氮、硝态氮、微生物生物量氮和可溶性有机氮含量。结果表明:各林窗内土壤铵态氮、硝态氮含量在融化末期显著高于其他3个关键时期;土壤微生物生物量氮在初融期最低,土壤可溶性有机氮含量在深冻期最低,而这两者含量在初冻期均最高;土壤硝态氮含量占土壤矿质氮总量的67.26%~83.59%;冬季林窗通过改变土壤微环境进而引起氮素组分的改变,林窗大小与可溶性有机氮含量呈显著正相关;土壤温度与铵态氮、硝态氮及可溶性有机氮含量呈显著正相关;冻结深度与硝态氮和可溶性有机氮呈显著负相关。经过季节性冻融期,小林窗和林下土壤具有更高的矿质氮和可溶性有机氮,为生长季内植被与土壤微生物奠定了良好的生长条件。
In order to understand the influence of alpine forest gap on soil nitrogen dynamics, four key periods (initial freezing, deep freezing and thawing Soil samples at the end of thawing and thawing, and the contents of ammonium nitrogen, nitrate nitrogen, microbial biomass nitrogen and soluble organic nitrogen were measured. The results showed that the content of soil ammonium nitrogen and nitrate nitrogen was significantly higher at the end of thawing than in the other three critical periods. The content of soil microbial biomass nitrogen was the lowest at the beginning of thawing period, and the content of soil soluble organic nitrogen was the lowest at the deep freezing period. While the contents of both were the highest in the initial freezing period; the contents of nitrate nitrogen in soil accounted for 67.26% -83.59% of the total soil mineral nitrogen; the changes of nitrogen components in winter canopy caused by changes of soil microenvironment, There was a significant positive correlation between soluble nitrogen and soluble organic nitrogen in soil. There was a significant positive correlation between soil temperature and ammonium nitrogen, nitrate nitrogen and soluble organic nitrogen. There was a significant negative correlation between freezing depth and nitrate nitrogen and soluble organic nitrogen. After seasonal freezing and thawing periods, the soil of Kobayashi and undergrowth had higher mineral nitrogen and soluble organic nitrogen, which laid favorable conditions for the growth of vegetation and soil microbes in the growing season.