内蒙古草原区植被净初级生产力及其与气候的关系

利用NOAA/AVHRR GIMMSNDVI数据、土地覆盖分类数据、气象数据等,基于改进的基于光能利用率的净初级生产力(Net Primary productivity,NPP)遥感估算模型对内蒙古草原区1982-2006年的NPP进行估算,并分别以年、季节和月为时间单位,计算基于像元的NPP与降水、温度之间的相关及偏相关系数,分析不同时间单位及尺度上NPP与气候的关系。结果表明,1982-2006年内蒙古草原区NPP总量呈波动增加的趋势,平均增加值为0.861Mt C/a。以年为时间单位,内蒙古草原区年NPP与降水的关系比较明显。以季节为时间单位,年际春季和夏季NPP与降水的关系比较明显,秋季二者关系相对较弱,春季和秋季NPP与温度的相关系数和偏相关系数空间格局比较一致,且相关性明显高于夏季。以月为时间单位的相关水平明显高于年际水平,多年平均年内月NPP与降水、温度的相关程度明显增强,除去降水的影响,月均温对NPP的影响明显下降,且空间格局也有明显的变化,说明以月为时间单位在年内尺度上降水对植被生长的影响比温度要大。而以4、7、10月份为例,在年际尺度上,虽然各月份NPP均受降水的影响较大,但与降水关系最为密切的是4月份和10月份NPP,与之相比,7月份NPP与温度的关系明显高于其他两月。

Net primary productivity (NPP) of grassland ecosystem and its relationship with climate in Inner Mongolia

Net primary productivity (NPP) of grassland ecosystem in Inner Mongolia from 1982 to 2006 was estimated using improved light use efficiency model using NOAA/AVHRR GIMMS NDVI, land use classification data and meteorological data. And the relationship between NPP and climate in different temporal unites (annual, season and month) and scales were analyzed based on correlation and partial correlation coefficients of the two-group elements. Results indicated that NPP tends to increase during 1982-2006, with an average of 0.861Mt C/a. The relation between NPP and climate in different unites and scales can be interpreted as follows: annual NPP of Inner Mongolia correlated more with precipitation than temperature, while interannual spring and summer precipitation influence NPP more seriously than that of autumn, but taking account of temperature, the correlation of summer NPP was the weakest. Correlation between month NPP and climate rises significantly than annual level. Multi-year average month NPP within a year strongly correlated with precipitation and temperature. Eliminating influence of precipitation, correlation coefficients of NPP and temperature dropped obviously and spatial distribution changed dramatically, which revealed that precipitation contributed more to vegetation growth than in month unite and within a year scale. Taking April, July and October for example, though NPP was affected more by precipitation, correlation coefficients of interannual April and October NPP with precipitation were larger than that of July and that showed contrary results in temperature.