银川盆地净初级生产力估算和趋势分析

【目的】基于2000—2010年间的遥感数据、气象数据,利用净初级生产力(NPP)估算模型模拟银川盆地NPP,分别从逐月、逐年对其时空变化过程进行分析,并进行预测分析,阐述11年期间银川盆地植被NPP的时空格局与变化特征,探讨NPP与植被健康指数(VHI)之间的耦合关系。【方法】选取2000—2010年间的SPOT VEGETATION数据、归一化植被指数(NDVI)、遥感数据、考虑了研究地区内及其周边气象站点数据等,利用CASA模型,一元线性回归、奇异值分解等方法对银川盆地NPP空间分布进行估算与分析。【结果】2000—2010年,银川盆地逐月NPP平均值呈现小幅度增长,月均增加0.51 g C·m~(-2),以7月、10月NPP值增长最为显著;2000—2010年,银川盆地逐年NPP平均值也呈小幅度增长,年均增加0.24 g C·m~(-2),NPP年平均值总体呈波动趋势,以2007、2009年NPP增长最为显著,降水直接导致了2005、2006年的NPP值出现低值;2000—2010年,从银川盆地NPP空间变化来看,行政区域年平均NPP物质量大小依次为:大武口区永宁县灵武市西夏区青铜峡市利通区平罗县贺兰县惠农区兴庆区金凤区。银川盆地NPP平均值表现出"南北高中间低、东高西低"的空间格局,其中NPP低值集中在西夏区、兴庆区、金凤区等区域;NPP趋势的好坏与村镇点数量大小、人口数量呈异步变化关系;银川盆地的VHI变高(低)时,NPP随之变低(高),第一模态左右场的相关系数为-0.69,呈现异步耦合关系。【结论】采用光能利用模型对银川盆地的NPP进行估算模拟和实测验证,发现其模拟结果与实测数据接近,该模型测算银川盆地的NPP较为合理;银川盆地NPP总体趋于良好,但局部区域出现恶化情况;银川盆地NPP波动明显,主要受土壤湿度的影响,因此NPP对干旱具有一定的指示作用。

Trend Analysis and Estimation of Net Primary Productivity in Yinchuan Basin

【Objective】The objective of this study is to simulate the net primary productivity (NPP) using the NPP model in Yinchuan Basin based on the remote sensing data and meteorological data from 2000 to 2010. The spatio-temporal changing process of NPP and its trend was analyzed (monthly and yearly), and the Yinchuan Basin’s vegetation NPP spatio-temporal pattern and variation were described for discussing the coupling relationship between the NPP and vegetation health index (VHI).【Method】Using SPOT VEGETATION data (1 km spatial resolution) from 2000-2010, as well as NDVI data and metrological data from 2000-2010, the NPP model was applied to analyze the spatial-temporal characteristics of NPP changes in Yinchuan Basin. The estimation was based on CASA model, linier regression equation and SVD method. 【Result】 Analysis of the spatial-temporal pattern of NPP showed that the NPP in Yinchuan Basin was increasing slowly at the rate of 0.51 per month, the most in July and October. The average annual change was 0.24, corresponding with the changes of rainfall. The NPP in Yinchuan Basin was higher in the south and east, while lower in the middle and west. The lowest value lies in Xixia region, Xingqing region and Jinfeng region: Dawukou District＞Yongning County＞Lingwu City＞Xixia District＞Qingtongxia City＞Litong District＞Pingluo County＞Helan County＞Huinong District＞Xingqing District＞Jinfeng District. The trend of NPP had a negative relationship with the amount of towns and the number of population. The correlation of the first mode was -0.69, showing the VHI made a negative influence on NPP. 【Conclusion】The estimated regional CASA model was precise to the actual data. The NPP in Yinchuan Basin was generally benign except some areas. Soil moisture can affect the NPP showing that drought can be predicted by using the value of NPP.