库布齐沙地四种植被类型土壤呼吸的昼夜变化及其影响因子

摘要

In order to elucidate carbon cycling in desert ecosystem,respiration of soils in four vegeta-tions in natural and artificial restoration and its environmental factors were investigated in Hobq sand.Soil respiration was measured in the vegetation growing season(July,2012)using LI-6400 Automated Soil CO2 Flux System.Soil temperature and water content,air temperature and moisture were also tested.The re-sults showed that the day and night time Rs pattern was different among four vegetations.The soil respira-tion rate of Artemisia ordosica community in fixed and half-fixed sandy land had a single-peak curve,Ca-ragana intermedia and Medicago sativa community showed a bimodal curve,peak values of soil respira-tion rate appeared in 12:00~16:00,minimum of Rs appeared in 3:00~6:00.Mean value of day-time Rs was significantly different from mean value of night-time Rs(P<0.01).In the growing season,there were differences in daily mean value of soil respiration rate among four vegetations,and the order was Medicago sativa>Caragana intermedia>Artemisia ordosica community in fixed sandy land>Artemisia ordosica community in half-fixed sandy land.The effect of interaction between soil temperature and water content on soil respiration rate was higher than that of soil temperature.The correlation between soil respiration rate and air temperature and moisture was highre in surface soil.%采用 Li-6400-09土壤呼吸室对库布齐沙地四种植被类型土壤呼吸速率进行测定,分析不同植被类型土壤呼吸速率昼夜变化特征、土壤呼吸日均值差异性及其对水热因子的响应.结果表明:(1)库布齐沙地四种植被类型土壤呼吸的昼夜变化格局不同,固定、半固定沙地油蒿群落呈单峰曲线,中间锦鸡儿群落和苜蓿草地呈双峰型,峰值总体出现在12:00~16:00,最低值出现在3:00~6:00之间;四种植被类型昼、夜间土壤呼吸速率具有极显著差异(P<0.01).(2)四种植被类型土壤呼吸速率日均值之间存在显著差异,大小为:苜蓿草地>中间锦鸡儿群落>固定沙地油蒿群落>半固定沙地油蒿群落.(3)土壤水热因子的交互作用对土壤呼吸速率的影响高于土壤温度单因子模型.(4)近地面大气温度、湿度与土壤呼吸速率的相关性要高于土壤水热因子,是影响四种植被类型土壤呼吸速率昼夜变化的主要因子.