期刊文献+
共找到1篇文章
< 1 >
每页显示 20 50 100
Estimation of spatial and temporal changes in net primary production based on Carnegie Ames Stanford Approach(CASA) model in semi-arid rangelands of Semirom County, Iran 被引量:9
1
作者 Fatemeh HADIAN Reza JAFARI +2 位作者 Hossein BASHARI Mostafa TARTESH kenneth dclarke 《Journal of Arid Land》 SCIE CSCD 2019年第4期477-494,共18页
Net primary production(NPP) is an indicator of rangeland ecosystem function. This research assessed the potential of the Carnegie Ames Stanford Approach(CASA) model for estimating NPP and its spatial and temporal chan... Net primary production(NPP) is an indicator of rangeland ecosystem function. This research assessed the potential of the Carnegie Ames Stanford Approach(CASA) model for estimating NPP and its spatial and temporal changes in semi-arid rangelands of Semirom County, Iran. Using CASA model, we estimated the NPP values based on monthly climate data and the normalized difference vegetation index(NDVI) obtained from the MODIS sensor. Regression analysis was then applied to compare the estimated production data with observed production data. The spatial and temporal changes in NPP and light utilization efficiency(LUE) were investigated in different rangeland vegetation types. The standardized precipitation index(SPI) was also calculated at different time scales and the correlation of SPI with NPP changes was determined. The results indicated that the estimated NPP values varied from 0.00 to 74.48 g C/(m^2·a). The observed and estimated NPP values had different correlations, depending on rangeland conditions and vegetation types. The highest and lowest correlations were respectively observed in Astragalus spp.-Agropyron spp. rangeland(R^2=0.75) with good condition and Gundelia spp.-Cousinia spp. rangeland(R^2=0.36) with poor and very poor conditions. The maximum and minimum LUE values were found in Astragalus spp.-Agropyron spp. rangeland(0.117 g C/MJ) with good condition and annual grassesannual forbs rangeland(0.010 g C/MJ), respectively. According to the correlations between SPI and NPP changes, the effects of drought periods on NPP depended on vegetation types and rangeland conditions. Annual plants had the highest drought sensitivity while shrubs exhibited the lowest drought sensitivity. The positive effects of wet periods on NPP were less evident in degraded areas where the destructive effects of drought were more prominent. Therefore, determining vegetation types and rangeland conditions is essential in NPP estimation. The findings of this study confirmed the potential of the CASA for estimating rangeland production. Therefore, the model output maps can be used to evaluate, monitor and optimize rangeland management in semi-arid rangelands of Iran where MODIS NPP products are not available. 展开更多
关键词 CASA NPP ESTIMATION light utilization efficiency vegetation type drought RANGELAND condition SEMIARID RANGELANDS
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部