喀斯特岩溶、非岩溶区植被总初级生产力与土壤呼吸的空间差异及其环境因子分析

Spatial Differences and It’s Environmental Factors of Vegetation Primary Productivity and Soil Respiration in Karst and Non-karst Areas

选取中国两个典型喀斯特石漠化生态系统(研究区Ⅰ广西盘阳河流域峰丛洼地石漠化区、研究区Ⅱ云南荞麦地流域中山山地石漠化区),通过遥感影像反演和广泛的野外验证,开展喀斯特生态系统植被总初级生产力(GPP)和土壤呼吸(Rs)的差异分析及其在地形地貌、海拔坡度、土地利用以及岩性等环境因子上的空间分异分析。结果表明:1)两个研究区雨季和非雨季的GPP均值均要大于Rs均值,峰丛洼地的GPP和Rs均值都要高于中山山地,但中山山地的Rs均值两级分异更为明显;2)GPP与海拔总体上呈现显著的负相关关系(在平均海拔较低的研究区Ⅰ更为明显),GPP均值在坡度大于25°左右时随着坡度的增加而减少;两个研究区的Rs均随着海拔的升高先降后增,坡度小于40°时呈负相关;3)不同土地覆盖类型GPP均值总体上呈现林地>灌丛>草地、耕地的规律,而Rs均值呈现出居住建设用地>耕地>草地>灌丛>林地的规律,常绿针叶林有着区域内最高的GPP值,城镇建设用地有着最高的Rs均值;4)研究区雨季与非雨季的GPP、Rs均值均呈现岩溶区小于非岩溶区的特点(p<0.001)。本研究可为西南喀斯特生态系统碳循环特征研究提供参考,为分析喀斯特区域碳汇特点和机制提供应用支撑,为区域制定侧重不同的生态策略提供思路和应用参考。

Two typical karst rocky desertification ecosystems in China( the peak cluster depression and rocky desertification area in the Panyang River Basin of Guangxi,research area Ⅰ,and the mountainous rocky desertification area in the Yunnan Qiaomaidi basin,research area Ⅱ) were selected as research areas to analyze total primary productivity( GPP) and soil respiration( Rs) of karst ecosystems and to analyze relations of their spatial differentiation with environmental factors,such as topography,elevation slope,land use and lithology,through remote sensing image inversion and extensive field verification. The results showed that: 1) the average values of GPP in rainy and non-rainy seasons of two study areas were larger than corresponding average values of Rs,and average values of GPP and Rs in the research area Ⅰ were higher than those in the research area Ⅱ,but the maximum Rs of the research area 2 was larger;2) GPP had a significant negative correlation with the altitude( more obviously in the research area I which has a lower average altitude),and average values of GPP decreased as slope increasing when the slope is greater than 25°;Rs was related to the elevation,Rs decreased first and then increased as the altitude increasing,but a negative correlation was found when the slope was less than 40°;3)The average values of GPP of different land cover types generally showed a rule of"forest land>shrubs>grassland and cultivated land",while the average value of Rs presented the rule of residential construction land>cultivated land>grassland>shrub>forest land,the evergreen coniferous forest had the highest GPP value in the study region and the urban construction land had the highest Rs mean value;4) No matter in rainy or non-rainy seasons,the average values of GPP and Rs in karst areas were smaller than those in non-karst areas( p<0.001). This study can provide reference for the study of carbon cycle characteristics of southwest karst ecosystems,provide application support for analyzing characteristics and mechanisms of carbon sinks in karst regions,and provide ideas and application references for regional development of different ecological strategies.