Zagros forest, the second most important renewable source of cellulose for Iran, is one of the best known oak forest reserves worldwide. These vital ecosystems hold great environmental and ecological importance in protecting water resources in the climatic dry conditions of the country. In recent years, however, oak dieback has decimated these forests. The purpose of our work is to evaluate and analyze the relationship of climate variables and the dieback of the Zagros oak forest in Lorestan Province, Iran. Dieback is defined by dieback indices, such as DVI, GEMI, IPVI, MSAVI2, NDVI, EVI, OSAVI, Sarvi2, SR, and VHI, which were obtained for 110 locations in the study area in the period between 2001 and 2017. On the other hand, daily climate variables influencing oak tree dieback were extracted in the same time period. As a first step, the most important climate variables affecting oak tree dieback were detected using the factor analysis method. Next, the so-called G* spatial correlation index was used to compute the covariance of dieback indices with climate variables as well as the spatial patterns of the changes of these covariances. The results of factor analysis showed that three factors, namely, humidity, temperature, and precipitation, were the most significant variables affecting dieback indices. Spatial autocorrelation patterns indicated that humidity played a major role regarding the widespread dieback in the study area. The mismatch of areas of low humidity and dieback indices, however, prompts that other factors, such as fungal diseases, affected the dieback alongside climatic variables. A similar investigation relating temperature with dieback indices indicated that changes in the match of spatial autocorrelation patterns of temperature and other dieback indices were less than 30% in terms of matching area except for NDVI and EVI. The effect of temperature on dieback indices was more limited to the southeast part of the study area. However, the covariance change pattern relating precipitation with dieback indices was related to northwest areas. Among all studied dieback indices, the NDVI was most correlated with all three factors of humidity, temperature, and precipitation, and temperature along humidity was found to play the most important role concerning the dieback of the Zagros oak forest.

扎格罗斯森林是伊朗第二大最重要的纤维素可再生资源，是世界上最著名的橡树林保护区之一。这些重要的生态系统在保护该国气候干燥条件下的水资源方面具有巨大的环境和生态重要性。但是，近年来，橡树死灰复燃使这些森林绝迹。我们的工作目的是评估和分析气候变量与伊朗洛雷斯坦省Zagros橡树林的枯死的关系。死背由死背指标定义，例如DVI，GEMI，IPVI，MSAVI2，NDVI，EVI，OSAVI，Sarvi2，SR和VHI，这些指标是在2001年至2017年期间从研究区域的110个位置获得的。另一方面，在同一时期提取了影响橡树枯萎的每日气候变量。第一步 使用因子分析方法检测了影响橡树枯萎的最重要的气候变量。接下来，使用所谓的G *空间相关性指数来计算回缩指数与气候变量的协方差以及这些协方差变化的空间模式。因子分析结果表明，湿度，温度和降水这三个因子是影响回缩指数的最重要变量。空间自相关模式表明，湿度对研究区域广泛的枯萎有重要作用。但是，低湿度和枯萎指数的区域不匹配，这提示其他因素（例如真菌病）与气候变量一起影响了枯萎。关于温度与回溯指数的类似研究表明，除NDVI和EVI以外，就匹配面积而言，温度与其他回溯指数的空间自相关模式的匹配变化小于30％。温度对回缩指数的影响更多地局限于研究区域的东南部。但是，降水与枯竭指数相关的协方差变化模式与西北地区有关。在所有研究的枯萎指数中，NDVI与湿度，温度和降水的所有三个因素最相关，并且沿着湿度的温度被发现对于Zagros橡树林的枯萎起着最重要的作用。