退耕还草对锡林郭勒草原总初级生产力变化的影响

Changes of gross primary productivity induced by returning farmland to grassland in Xilin Gol Grassland

内蒙古草原是我国重要的生态保护屏障,部分区域是农牧交错带的重要组成部分。锡林郭勒草原位于内蒙古东中部,属典型温性草原,深入开展退耕还草对其植被总初级生产力(GPP)的影响、探究相关环境因子,对深入了解退耕还草过程中区域植被生长状况变化和生物固碳潜力时空分布以及制定更加科学精准的退耕政策具有重要意义。基于遥感、气象观测和土地利用数据,采用残差分析和相关性分析方法,系统研究了2010—2015年间锡林郭勒草原退耕还草区域的植被GPP变化特征,并探讨了不同环境因子对GPP变化量的影响,揭示了退耕还草活动造成的GPP变化特征及其受环境因子影响的作用机制。结果发现:(1)锡林郭勒盟退耕还草区域5年内GPP平均变化量为0.47 g C/m^(2),其中GPP增加面积占退耕还草总面积的67.2%,退耕还草初期GPP变化不显著;(2)退耕还草区域内,土壤含水量和土壤有机碳与GPP变化量显著负相关,而气温、降水、高程和坡度均与GPP变化量显著正相关;(3)坡度和土壤含水量与GPP变化量的相关程度最强,对退耕还草后GPP变化的影响程度较高。

Inner Mongolia grassland is an important ecological protection barrier in China and part of it is the important agro-pastoral ecotone,but it is dry and windy,with fragile surface material structure,strong soil erosion,and extremely fragile ecological environment.Located in the mid-eastern Inner Mongolia grassland,Xilin Gol Grassland is a typical temperate grassland.In-depth research on the impact of returning farmland to grassland on the gross primary productivity(GPP)of land vegetation in Xilin Gol Grassland and related environmental factors is of great significance to understand the regional vegetation growth status and biological carbon sequestration capacity in the project of returning farmland to grassland as well as to formulate scientific policies for returning farmland to grassland.We use the VI model to estimate the GPP change in the Xilingol Grassland Conversion Area from 2010 to 2015.Based on MODIS remote sensing data,ground observation data,environmental factor data and land use data,this paper systematically studied the characteristics of the GPP change of land vegetation in the area of returning farmland to grassland in Xilin Gol Grassland from 2010 to 2015 by using residual analysis,correlation analysis and partial correlation analysis,and discussed the impact of different environmental factors on the GPP change,and revealed the characteristics of the GPP change and the active mechanism of environmental factors after returning farmland to grassland.The results showed that:(1)the average GPP change in the area of returning farmland to grassland in Xilin Gol League within 5 years was 0.47 g C/m^(2),in which the area with an increased GPP accounted for 67.2%of the total area of returning farmland to grassland,and the GPP change in the initial stage of returning farmland to grassland was not significant;(2)In the area of returning farmland to grassland,soil water content and soil organic carbon were significantly negatively correlated with the GPP change,while air temperature,precipitation,elevation,and slope were significantly positively correlated with the GPP change,and there is no significant correlation between soil nitrogen content,soil phosphorus content,and soil potassium content with GPP change;(3)Slope and soil water content had the strongest correlation with the GPP change,and had a higher impact on the GPP change after returning farmland to grassland,precipitation and oil organic carbon had the strongest correlation with the GPP change,environmental conditions have a significant impact on the GPP change after returning farmland to grassland.