黄土丘陵区土壤基础呼吸对草地植被恢复的响应及其影响因素

为探讨黄土丘陵区草地植被自然恢复过程中土壤微生物活性的变化特征及其影响因素, 采用"时空互代"法采集宁夏云雾山自然保护区8个不同植被恢复年限的春、夏两季0～20 cm和20～40 cm的土样, 用室内密闭静态培养-碱液吸收法测定了新鲜和风干土样的基础呼吸.结果表明: 土壤基础呼吸随植被恢复年限增加呈增加趋势, 土壤呼吸强度和累积呼吸量都表现为植被恢复73年和78年较高, 而耕地和植被恢复3年最低.采样季节对呼吸强度测定有较大影响, 春季土样能更好地反映土壤微生物活性的变化.风干土样可以通过预培养后测定土壤的呼吸作用, 且能更加稳定地反映不同土壤之间的差异.在测定土壤基础呼吸时, 利用 1 d或3 d的培养平均值能更稳定地表现不同土壤的特性.累积呼吸量可较呼吸强度更直观地反映不同土壤的微生物活性.土壤有机质和全氮含量与土壤呼吸强度密切相关.

Soil basal respiration response to grass vegetation restoration and its' affecting factors in the Loess Hilly-Gully Region

Soil respiration response to different stages of vegetation restoration was determined via closed system measurements of carbon dioxide and selected factors affecting the correctitude and sensitivity of soil respiration. Eight different soil samples under different vegetation restoration stages were separately collected at 0~20 cm and 20~40 cm soil depth in spring and summer and both fresh and air-dried samples analyzed. The results show that the period of vegetation restoration significantly influences soil basal respiration (SBR), which logarithmically increases with vegetation recovery time. Measurements of equivalent daily respiration (EDR) and cumulative respiration (CR) show that respirations in 73- and 78-year recovery sites are highest, while those in farmland and 3-year recovery sites are lowest. SBR is distinctly different for the spring and summer samples. SBR of spring samples better reflect soil basal microbial activity. Air-dried soils can be used for measuring SBR after pre-incubation, more stably reflecting difference among soils. 1 or 3-day EDR mean data can better reflect soil quality. CR more directly and clearly reflects microbial activities of different soil types than EDR. There is a positive correlation between SBR and soil organic carbon and nitrogen content.