紫色土丘陵区典型林地土壤温室气体释放研究

采用动态-密闭气室法(LI-6400-09)对紫色土丘陵区三种典型林地土壤温室气体释放进行连续测定.结果表明,温度是影响土壤呼吸的关键因子,各林地土壤呼吸速率与土壤温度呈正相关,都随温度呈指数增长.在温度较低的冬春季,土壤湿度对土壤呼吸的影响不明显,温度较高的夏季土壤湿度与林地(桤树,柏树)土壤呼吸速率呈显著性抛物线相关(p＜0.05);三种林地中,针叶林柏树林地土壤呼吸与土壤湿度相关性最好,当土壤含水量＜25%时,随着湿度的增加,土壤呼吸速率逐渐增大,之后随着湿度的增大,土壤呼吸速率逐渐减小.各季节的日变化规律表现不一致,冬春两季各林地土壤呼吸都和土壤温度的日变化趋势保持一致,表现为先升后减的趋势;夏秋两季,因为较高的土壤温度和表层土壤相对湿度的剧烈波动,各林地土壤呼吸日变化呈现不规则波动.

A Study of Emission of Greenhouse Gases from Soil in Different Forestland of Hilly Area in Central Sichuan Province

Soil respiration rate are measured by LI-6400 in three types of forestland in the hilly area of the central Sichuan basin.The mainly researches are focused on the characteristics and influencing factors of soil respiration and the litter fall respiration,organic matter in soil and organic carbon in litter are measured to estimate the quantity of carbon released by litter decomposition.The results and conclusions are as follows: soil respiration in three kinds of woodlands showed remarkably seasonal changes,which were higher in summer and autumn and lower in spring and winter.The soil respiration rate of forestland soil with litter is higher than the non-litter-covered soils.The litter layer on the soil surface of beech land could be low down the emission of CO2 from soil to atmosphere.soil temperature and soil moisture are primary impact factors of soil respiration.There is a significant correlation between soil respiration rates and soil temperature at 5 cm depth.The impact of soil moisture on soil respiration has a seasonally performance.There are parabola correlations between the soil respiration and the soil moisture in summer.There are not correlations between soil moisture and soil respiration in other seasons.Diurnal changes of soil respiration are accorded with that of the soil temperature in winter and spring but not in summer and autumn,in which irregular peaks are displayed in the diurnal changes because of the high soil temperature and the intense changes of the relative moisture.