Understanding the spatial and temporal patterns of net ecosystem productivity(NEP)is important for improving ecosystem functions in arid/semi-arid regions.Most existing studies on spatial and temporal patterns of NEP have been analyzed at the annual scale,and the differences in the characteristics of NEP at multiple time scales are not yet clear.Based on the data of multi-source remote sensing,meteorological and ground-truthing,the CASA model,the geostatistical model of soil respiration(GSMSR),and the soil respiration-soil heterotrophic respiration(Rs-Rh)relationship model were used to couple and simulate the NEP in Inner Mongolia from 2001 to 2020,and analyze the temporal and spatial characteristics of the NEP at multi-temporal scales of years,seasons,and months.Then the differences in multi-timescale characteristics of eight different vegetation NEPs were explored.The results show that 1)the spatial distribution pattern of annual NEP in Inner Mongolia was stable,decreasing from northeast to southwest,which was consistent with the spring,summer,and fall seasons and the growing period of vegetation from March to October.However,the spatial difference was significantly reduced in winter when the vegetation enters the dormant period.2)The interannual trends of NEP in Inner Mongolia at multiple time scales were different.On the annual scale,the total NEP in Inner Mongolia showed a fluctuating upward trend,with an interannual rate of change of C 3.75 Tg∙a-1.On the seasonal scale,the summer season showed the largest growth trend,accounting for 41.6%of the annual growth.Both spring and fall seasons played crucial roles in the growth of NEP,which accounted for 34.9%and 23.3%,respectively,while,the contribution of winter to NEP growth was very limited.On the monthly scale,the annual change of NEP was close to the vegetation growth cycle,with decreasing trend in January and December,but increasing trend in the rest of the months,with the largest growth trend in September,accounting for 19.3%of the annual growth.3)There are differences in the interannual NEP trends of different vegetation types.Five vegetation types showed an increasing trend in annual NEP and three showed a decreasing trend.Grassland kept increasing in all seasonal-scale interannual changes,with highest growth in the summer.Shrubland showed a decreasing trend in all seasonal-scale interannual changes and monthly-scale inter-annual changes,with the greatest decrease in the summer and January,respectively.This study can provide a scientific basis for clarifying the regional carbon cycle and improving ecosystem functions.
关键词
净生态系统生产力/多时间尺度/分布格局/CASA模型/GSMSR模型/内蒙古
Key words
net ecosystem productivity/multiple time scales/distribution pattern/CASA model/GSMSR model/Inner Mongolia
维普
万方数据