TANG Rongbin¹, FU Meichen¹, WANG Li², HUANG Ni², LIAN Haifeng³

（1. School of Land Science and Technology, China University of Geosciences(Beijing), Beijing 100083, China;
2. Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;
3. School of Computer and Informatics, Fujian Agriculture and Forestry University, Fuzhou 350002, China

Abstract: 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 1, and the mountainous rocky desertification area in the Yunnan Qiaomaidi basin, research area 2) 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 1 were higher than those in the research area 2, 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.

Key words: carbon balance; karst and non-karst areas; gross primary productivity; soil respiration; spatial differentiation

EARTH AND ENVIRONMENT Vol.48, No.3, Tot No.335, 2020, Page 307-317