上海城市绿地不同植物群落土壤呼吸及因子分析

摘要

用CFX-2开放式呼吸测定系统对上海城区9种植物群落进行了土壤呼吸速率的测定及其影响因子的探讨.结果表明:9种植物群落的土壤呼吸速率均呈明显季节变化,土壤呼吸速率最大值出现在6-9月,最小值出现在12-3月;但土壤呼吸速率日变化有乔灌木较平稳,草坪呈单峰曲线的趋势;9种植物群落平均土壤呼吸速率的总体差异极为显著(P＜0.01),狗牙根Cynodon dactylon草坪最高,为5.51 μmol·m-2·s-1,是呼吸速率最低的紫荆Cercis sp.群落的2.76倍；9种植物群落的土壤呼吸速率与气温、5 cm地温和10 cm地温均呈极显著指数相关(P＜0.01),但地温Q10(温度系数,温度每变化10 ℃,呼吸速率的相对变化)值高于气温,且5 cm和10 cm地温对土壤呼吸速率的影响较小；土壤易变碳的大小顺序为轻组有机碳＞微生物量碳＞可溶性碳,但土壤呼吸速率受土壤微生物量碳和可溶性碳的影响较大;草坪群落二氧化碳的年释放量最大,达到了33.18 t·hm-2·a-1,是乔木林的1.95倍,是灌木丛的2.12倍.%The soil respiration rate of nine plant communities (Cinnamomum camphora, Torreya grandis-Ginkgo biloba, Cedrus deodara, Ginkgo biboba, Osmanthus fragrans , Cercis sp., Lolium perenne-Cynodon dactylon, Zoysiajaponica, and Cynodon dactylon) in Shanghai City were studied with a CFX-2 Soil Respiration Chamber, and the main influential factors were identified, and the aim was to evaluate correctly soil respiration of urban soil. The digital thermometer was used to test the air temperature, the soil temperature at 5 cm depth and the soil temperature at 10 cm depth. And all data were average of three replications, and a correlation analysis was also employed. Results showed that soil respiration rates varied by season with the maximum found from June to September and the minimum from December to the following March. Daily variation in the soil respiration rate under communities of trees and bushes was generally stable; whereas a lawn had a single-peaked curve. The maximum soil respiration rates (5.51 mol·m-2·s-1) found under Cynodon dactylon and the minimum (2.76 times less) found under a Cercis sp. community. The soil respiration rate had a significant exponential correlation (P<0.01) with the air temperature, the soil temperature at 5 cm depth, and the soil temperature at 10 cm depth. Soil water content had an effect on soil respiration under lawns, but it had a relatively small influence on tree and bush communities. The soil labile organic carbon content was ranked in the following order: light fraction organic carbon (LFOC) > microbial biomass carbon (MBC) > dissolved organic carbon (DOC), but MBC and DOC had the greatest influence on the soil respiration rate. The maximum released quantity of CO2 reached to 33.18 t·hm-2·a-1 under lawns, which was 1.95 times that of trees and 2.12 times that of bushes.