论文部分内容阅读
放牧及围封是引起沙质草地生态系统变化的重要因素。对科尔沁地区放牧和围封不同年限的沙质草地进行土壤呼吸动态测定与分析,结果表明:(1)植物生长初期土壤呼吸速率日平均值,围封样地的显著大于放牧样地的(p<0.05);植物生长末期土壤呼吸速率日平均值,放牧样地的显著大于围封样地的(p<0.05)。围封17年和围封22年样地的土壤呼吸速率日平均值相比较,7月上旬之前,围封17年样地的较围封22年样地的大,而7月中旬以后,围封22年样地的较围封17年样地的大,且差异均显著(p<0.05)。(2)土壤呼吸速率的季节动态对放牧和围封的响应过程相似,但围封引起的变异相对较小;土壤呼吸速率季节平均值,围封22年样地的显著大于围封17年的(p<0.05)和放牧的(p<0.01),围封17年样地的大于放牧的(p>0.05),故围封可以增强土壤CO2的排放,且在一定的时间内,土壤CO2的排放速率与围封时间正相关。(3)土壤温度和土壤体积含水率可解释土壤呼吸速率的变异从大到小依次为放牧(58%)>围封22年(39%)>围封17年(28%)。
Grazing and enclosure are the important factors that cause the change of sandy grassland ecosystem. The results showed that: (1) The daily average of soil respiration rate in the initial stage of plant growth was significantly larger than that in the grazing plot (p <0.05). The daily average of soil respiration rate at the end of the plant growth stage was significantly higher than that of the grazing plot (p <0.05). Compared with the daily average of soil respiration rate of the 17-year enclosure and the 22-year enclosure, in the first ten days of July, the 17-year-old plot was more enclosed than that of the 22-year-old plot. After mid-July, In the 22-year plots, there was a significant difference between the two plots in the 17-year plots (p <0.05). (2) The seasonal dynamics of soil respiration rate was similar to that of grazing and enclosure, but the variation caused by enclosure was relatively small. The seasonal average of soil respiration rate was significantly larger in the 22-year plots than in the 17-year (p <0.05) and grazing (p <0.01), and enclosing the 17-year-old plot was more than that of grazing (p> 0.05), so the enclosure could enhance the soil CO2 emission, and within a certain period of time, The discharge rate is positively correlated with the confinement time. (3) Soil temperature and soil water content can explain the variation of soil respiration rate in descending order of grazing (58%), sealing time of 22 years (39%), sealing time of 17 years (28%).