燕沟流域土壤微生物学性质对植被恢复过程的响应

以黄土高原丘陵区陕北延安燕沟流域为例,研究了退耕地土壤微生物生物量对植被恢复过程的响应。结果表明,随植被恢复年限的增加,植被盖度、多度和物种数均呈现先增加后减少然后又增加的趋势。同对照农地相比,表层(0—5 cm)土壤呼吸速率和土壤微生物生物量均明显增加。表层土壤呼吸速率和微生物量碳、氮、磷分别比对照农地增加31.61%3~60.75%和15.19%5~12.81%、122.91%6~97.15%、193.5%2~068.17%。表层土壤呼吸速率对植被恢复的响应是在植被恢复初期(02~9年),随植被恢复年限的增加而增加;植被恢复305~5年期间,随植被恢复年限的增加而减少;而植被恢复55年以后,又随植被恢复年限的增加而增加。植被恢复过程中,土壤微生物量碳、氮和磷的变化与土壤呼吸速率变化趋势类似。除植被恢复8和16年外,植被恢复年限间的土壤呼吸速率、呼吸熵和微生物量碳、氮、磷均有显著性差异。表层土壤呼吸速率与土壤微生物量氮、磷呈极显著相关,土壤微生物量碳与土壤微生物量氮呈显著相关;而土壤呼吸熵与呼吸速率和微生物量碳、氮、磷相关性不明显。

Soil microbial biomass characteristics in response to vegetation restoration on abandoned lands in Yangou watershed of China

Taking the Yangou watershed located in the hilly-gully region of the Loess Plateau as an example, the responses of soil microbial biomass characteristics to vegetation restoration on abandoned lands were studied. The results showed that with an increase of vegetation restoration years, vegetation coverage, vegetation abundance, and amount of species increased at the beginning of vegetation restoration(4-16 years), then decreased(16-29 or 16-55 years), and later increased again(after 30 or 55 years). Respiration rate and microbial biomass of topsoil(0-5 cm)significantly increased compared to cropland with topsoil respiration rate, microbial biomass C, microbial biomass N and microbial biomass P increased by 31.61%-360.75%, 15.19%-512.81%，122.91%-697.15% and 193.5%-2068.17%, respectively. At the early stages of vegetation restoration(0-29 years), topsoil respiration rate increased with an increase of vegetation restoration years, then decreased at 30-55 years of vegetation restoration, and then increased again after 55 years of vegetation restoration. With vegetation succession, the changing tendency of topsoil microbial biomass C, N, and P were similar to that of soil respiration rate. Soil respiration rates, soil respiratory quotients, soil microbial biomass C, N, and P in different restoration years showed significantly different except in 8 and 16 years. Topsoil respiration rate was significantly correlated with soil microbial biomass N and P, but soil respiratory quotient was not significantly correlated with soil respiration rate, soil microbial biomass C, N, and P.