Iranian Journal of Applied Ecology

Drought is one of the main factors of ecological potential stress due to the wide extension of the time scale and impact space. The performance of regional drought monitoring using the meteorological indicators is a challenge due to spatial distribution constraints. In present study, 168 time series images including NDVI and LST indices were used. Integrating these two indices, VSWI was used to assess near-real-time and spatial-temporal spatial drought monitoring in Gavkhoni basin during 2003 to 2014. The SPI was assigned as the basis and the feedback of satellite and meteorological indices was assessed using Pearson correlation test. The results of the study of the relationships between the mean annual values of the VSWI and SPI indices during the same period showed a value of 0.578. In order to study the significance of the indices correlation, a nonparametric Spearman correlation test was added to the study. In addition, the results of the spatio-temporal pattern of the annual VSWI, indicating a severe long-term drought in the southeastern parts of the Zayandehrud dam and the entire Gavkhoni wetland area. The adaptation of this map to the meteorological drought map indicates the efficiency of integrating NDVI and LST satellite indices in drought monitoring.

Currently, there is little information on the high mountain species' response to the climate change in Iran, and it seems that these species are significantly affected by the climate change. In the current research, the spatial vulnerability of Caspian snowcock (Tetraogallus caspius) to the  climate change in Chaharmahal and Bakhtiari province was predicted using the ensemble modelling approach, based on seven species distribution models. According to the findings, about 19.43% of the province was estimated to be the suitable habitat of Caspian snowcock. The variables of annual precipitation (23.23%), annual temperature range (21.82%), human footprints (15.77%) and slope (14.46%) had the highest contributions to the model. Findings also showed that about 12.9- 32.28% of the suitable habitats might be lost by 2050 due to the climate change, based on the two scenarios of increased greenhouse gases (RCP4.5 and RCP8.5) and the HadGEM2-CC model. At the same period, it is expected that the suitable habitats of the Caspian snowcock in the low altitude areas  would be lost. Additionally, due to the climate change, some populations, especially in the far southern regions of the province, will undergo local extinction or  may be completely isolated. Findings of this research can be, therefore, useful for adopting more appropriate approaches in order to manage and protect the Caspian snowcock populations in the country.

The present study was conducted to investigate NPP changes and its relationship with drought. The monthly time series of NPP for the country's rangelands was prepared from the sum of net photosynthesis production (PSN) of the eight-day MODIS sensor (MOD17A2H) with a spatial scale of 500 m for 2000 to 2022.The monthly rainfall data of 165 synoptic stations were obtained from the National Meteorological Organization to calculate the Standard Precipitation Index (SPI) and monitor droughts in this period. Box plots of precipitation and NPP were prepared and showed that the highest values of NPP with an average of more than 50 gC.m-2month-1 occur during spring and early summer in humid areas. Results showed that NPP is increasing in Iran's rangeland ecosystems, and on average, the NPP of all rangeland ecosystems in the country is about 112.6 ± 13 gC.m-2.year-1  ,in other words, about 76 million tons of carbon per year. It is absorbed by the plants in the rangeland ecosystems of the country. The trend of changes in the monthly series of NPP was not significant due to the influence of seasonal characteristics, but the annual changes of NPP showed a significant trend of increase in all regions.