土壤环境对陇东黄土高原刺槐林土壤碳通量的影响

Effects of soil environment on soil carbon flux of Robinia pseudoacacia forest at different stand ages in Longdong Loess Plateau

土壤环境是影响人工林土壤碳通量的关键因素之一。以甘肃陇东不同林龄(12、14、15和18 a)刺槐林和荒草地为研究对象,采用Li-8100系统定位,监测土壤碳通量,并对土壤温度(5 cm)、地表温度、土壤含水量和土壤有机质等因子进行监测。结果表明:1)地表温度和土壤温度与土壤碳通量显著相关(P<0.01),拟合程度64.64%~96.27%,相比地表温度,土壤碳通量对土壤温度的变化更为敏感,Q10值为2.21~4.36;其中,15和18 a刺槐林Q10值较大,荒草地Q10值最小。2)土壤含水量与土壤碳通量显著线性相关(P<0.01),但拟合度较低,仅可以解释土壤碳通量变化的19.57%~36.70%。3)土壤养分质量分数的高低,影响土壤碳通量的释放速度,12 a到14和15 a的刺槐林土壤养分增量明显。各因子中,土壤温度是土壤碳通量变化的主导因子。研究结果可为探究陇东黄土高原林地土壤碳通量机理提供数据支撑。

[Background] Soil environment is one of the key elements affecting soil carbon flux on artificial plantations. This study investigated the mechanisms between soil environmental factors and soil carbon flux thus distinguishing the main driving factors for soil carbon flux,which remained poorly understood to date. [Methods] This study was carried out to understand the soil carbon flux of Robinia pseudoacacia for different restoration periods（ 12,14,15,and 18 years） in the Longdong Loess Plateau.Soil carbon flux of different stand ages were monitored by Li-8100 system and the grassland was used as control. Meanwhile, the soil environmental factors such as soil organic matter, soil moisture soil temperature at 5 cm and surface temperature were detected simultaneously. The experimental data were analyzed and plotted by Excel2007. The correlation analysis was carried out by SPSS21. 0,and the fitting degree between soil carbon flux and temperature,soil water content and single factor and two factors was tested. [Results]1） The surface temperature and soil temperature were significantly correlated with soilcarbon flux（ P 0. 01）, the degree of fitting was 64. 64%-96. 27%. Compared with surface temperature,soil carbon flux was more sensitive to soil temperature,and the values of Q10 varied from2. 21 to 4. 36. The highest value was detected in 15 and 18 years,whereas the grassland exhibited the lowest. 2） There was a significant linear correlation between soil carbon flux and soil moisture（ P 0. 01）,while the regression model can only explain the variation of soil carbon flux by 19. 57%-36. 70%. 3） Total nitrogen,available nitrogen,available phosphorus,available potassium and soil organic matter showed similar trend in different stand ages,all of these decreased with the increase of soil depth. In the top soil layer（ 0-10 cm）,soil nutrients showed the highest value while the lowest values were at 60-100 cm soil layer. The level of soil nutrient contents affected the release rate of soil carbon flux. The soil nutrient contents of 14 and 15 years increased rapidly. [Conculsions]Soil temperature is the main driving factor for determining soil carbon flux. Our results may provide data for exploring the mechanism of soil carbon flux in the Longdong Loess Plateau.