Accumulation of Organic Matter in Infertile Red Soils and Its Ecological Importance

Field experiments on the decomposition of organic materials and the accumulation of organic carbon ininfertile red soils were conducted at the Ecological Experimental Station of Red Soil, the Chinese Academyof Sciences, and the potential of CO2 sequestration by reclamation and improving the fertility of these soils was estimated. Results showed that in infertile red soils, the humification coefficients of organic materials were rather high, ranging from 0.28 to 0.63 with an average of 0.43, which was 41% higher than those incorresponding red soils with medium fertility. This was mainly attributed to the high clay content, highacidity and low native organic matter content of infertile red soils. Compared to those in correspondingnormal red soils, the decomposition rates of organic materials were significantly lower in infertile red soilsin the first 2 yearst thereafter no significant difference was observed between those in the two kinds of soils.Depending on the kind and amount of organic manure applied, the soil properties and the rotation systems,annual application of organic manure with a rate of 4500 to 9000 kg ha-1 increased the organic carboncontent in surface 20 cm of infertile red soils by 2.1~7.5 g kg-1 with an average of 4.7 g kg-1 within the first5 years. The organic carbon content in infertile red soils which received organic manure annually increasedlinearly in the first 10 years, thereafter it slowed down, implying that the fertility of the infertile red soilscould reach middle or high level in 1O years if the soil was managed properly It was estimated that throughexploitation of wastelands, re-establishment of fuel forests and improvement of soil fertility, soils in red soilregion of China could sequester an extra 1.50 × 1015 g of atmospheric CO2.

Assessment of ecological importance of the Qinghai-Tibet Plateau based on ecosystem service flows

Assessments of ecological importance based on static indexes that do not consider service flows frequently underestimate the importance of the Qinghai-Tibet Plateau as a "source".On the basis of natural environmental characteristics,this study selected six type of ecosystem services for evaluation,including water retention,soil retention,carbon sequestration,biodiversity conservation,sandstorm prevention,and tourism.According to the attributes of each ecosystem service flow,we calculated the flow length and traffic accessibility indexes,using Arc GIS hydrological module and kernel functions separately,to comprehensively analyse the ecological importance levels of the Qinghai-Tibet Plateau.Results showed that after considering the service flows,the ecologically important zone shifted to the core area of the Three River Source Region,such as Zadoi County located in the Tanggula Mountains.The area of extreme importance is mainly distributed in the Yarlung Zangbo River basin,Tanggula Mountains,Hengduan Mountains,and Qilian Mountains,which accounts for 31.7% of the Qinghai-Tibet Plateau,providing approximately 60% of the ecosystem services and having extremely high protection efficiency and protection value.By introducing ecosystem service flow indexes,this study confirmed the ecological importance of core source areas such as the Tanggula Mountains,weakened the space bias caused by not considering the spatial transfer of ecosystem services,and provided technical support for optimizing ecological protection strategies and coordinating regional development.

Identifying the priority areas for enhancing the ecosystem services in hilly and mountainous areas of southern China

Ecosystem services can be enhanced through ecological restoration,industrial structure adjustment,land-use optimization,and agricultural and forestry ecosystem transformation.The ecosystem services in hilly and mountainous areas of southern China are crucially needed to be enhanced since these regions are important ecological functional zones in China.However,due to its large area,it is not possible to simultaneously upgrade the ecosystem services for all areas,and therefore,priority areas need to be selected to individually upgrade the ecosystem service function.In this study,via an approach of combining remote sensing,geographic information system,and spatial statistics,we identify the priority areas that need to be upgraded based on the analysis of ecological sensitivity,importance of ecosystem service function,and decreased degree in ecosystem services.For five counties in hilly and mountainous areas of southern China,only less than 2% of the total area was identified as the first priority area;its land-use compositions were analyzed and recommendations on how to enhance ecosystem service were suggested.This approach overcomes the conflict and contradiction issues associated with identifying priority areas in previous studies and solves the problems of high cost or difficult implementation of priority areas.