Abstract

This study explored the spatiotemporal variability of rangeland NPP in response to drought in Chaharmahal and Bakhtiari province, Iran, from 2000 to 2016 using the Carnegie Ames Stanford Application (CASA) model and Standardized Palmer Drought Index (SPDI). The spatial distribution of NPP and Light Use Efficiency(LUE) values, especially during dry years, indicated a larger dwindling rate for annual NPP and LUE in poor and very poor conditions compared to fair and good rangelands. During the nine-year drought period (2008–2016), NPP decreased across all rangelands, with the highest average of 5.14 g C/(m².a) and maximum of 6.42 g C/(m².a) in annual grass-annual forb and the lowest of 0.95 g C/(m².a) in the Daphne-Astragalus type. The correlation between SPDI and NPP varied from R² > 0.85 (p < 0.001) and R² < 0.1 (p > 0.01) among the rangeland types. The highest and the lowest sensitivity to drought were observed in the annual plants and shrublands, respectively.

中文翻译：

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基于SPDI指数的伊朗中部牧场NPP对干旱的时空响应

摘要

这项研究使用卡内基·埃姆斯·斯坦福应用（CASA）模型和标准化的帕尔默干旱指数（SPDI），探讨了伊朗查马哈尔和巴赫蒂亚里省2000年至2016年牧场NPP对干旱的时空变异性。NPP的空间分布和光利用效率（LUE）值，特别是在干旱年份，表明在较差和极差条件下，年均NPP和LUE的减少率要比公平和良好的牧场高。在九年干旱期间（2008-2016年），所有牧场的NPP均下降，年草最高平均值为5.14 g C /（m ² .a），最高为6.42 g C /（m ² .a）。一年生Forb，在达芙妮-黄芪中最低，为0.95 g C /（m ² .a）类型。在草地类型中，SPDI和NPP之间的相关性在R ² > 0.85（p <0.001）和R ² <0.1（p > 0.01）之间变化。在一年生植物和灌木丛中分别观察到最高和最低的干旱敏感性。