祁连山区是我国西部重要的生态安全屏障和固碳场所。为准确评估祁连山区青海云杉林生态系统生长季碳汇特征，利用涡度相关技术并结合增强回归树模型与结构方程模型，研究生长季其碳通量变化特征及其环境影响机制。结果表明，青海云杉林生长季净生态系统碳交换(net ecosystem carbon exchange，NEE)日变化呈"V"型，CO2通量变化范围在-0。71～0。08 mg CO2·m-2·s-1，季节尺度NEE变化范围在-20。93～11。75 g C·m-2，月均碳吸收量(188。27±17。85)g·m-2，生长季累积碳吸收941。34 g·m-2。增强回归树模型揭示植被指数对净生态系统碳交换量相对贡献率最高，为50。3%，其次是净辐射，为15。9%。结构方程模型表明，植被指数与相对湿度对净生态系统碳交换量的直接作用系数分别为0。61与-0。17。多元逐步回归模型表明植被指数与相对湿度对NEE具有显著影响(R2=0。74，P<0。01)。随着植被指数增加，祁连山森林生态系统碳汇功能显著增强。结果为准确评估祁连山区青海云杉林生态系统碳汇能力提供科学依据。
Carbon Sink Characteristics and Regulatory Factors of Qinghai Spruce Forests in the Qilian Mountains
Qilian mountain is an important ecological safety barrier and carbon sequestration site in western China.In order to accurately evaluate the characteristics of carbon sinks in the growing season of the Qinghai spruce forest ecosystem in Qilian mountains,this study used vortex correlation technology and combined with boosted regression trees and structural equation model to study the characteristics in the growing season carbon flux change and its environmental impact mechanism.The results showed that the daily variation of spruce forest net ecosystem carbon exchange(NEE)in Qinghai was"V"type,the CO2 flux variation ranged from-0.71 to 0.08 mg CO2·m-2·s-1,the seasonal scale variation range of NEE was-20.93～11.75 g C·m-2,the average monthly carbon uptake was(188.27±17.85)g·m-2,and the cumulative carbon uptake during the growing season was 941.34 g·m-2.The boosted regression trees revealed that the relative contribution of vegetation index to net ecosystem carbon exchange was highest at about 50.3%,followed by net radiation of 15.9%.The structural equation model showed that the coefficients of direct influence of vegetation index and relative humidity on net ecosystem carbon exchange were 0.61 and-0.17,respectively.Multiple stepwise regression models showed that vegetation index and relative humidity had significant effects on NEE(R2 =0.74,P<0.01).With the increase of vegetation index,the carbon sink function of forest ecosystem in Qilian mountains was significantly enhanced,which provided scientific basis for accurate assessment of carbon sequestration capacity of Qinghai spruce forest ecosystem in Qilian mountain area.
国家科技期刊平台
NSTL
万方数据
维普
