Relationships between NDVI and climatic factors in mountain ecosystems: A case study of Armenia

In this paper, we study vegetation, temperature, and precipitation dynamics, as well as their correlations and lag-time effects in mountain ecosystems of Armenia using SPOT/VGT NDVI data over the period 1998–2013. Three study sites near the Sisian, Megri and Kajaran meteorological stations were chosen, representing steep, xerophytic and meadow vegetation types, respectively. The results showed a significant increase in NDVI across the growing season during the study period. Meanwhile, a significant increase in mean precipitation and temperature during the growing season was detected for the Kajaran station. A negative correlation was observed between temperature and xerophytic/steep vegetation NDVI and positive correlation between temperature and meadow vegetation NDVI, while correlations between precipitation and NDVI for all vegetation types were positive. Moreover, the response of vegetation to climatic factors exhibited a time-lag effect. In general, the temperature and precipitation in the 2nd and 3rd 10-day intervals of April have a strong impact on the vegetation growth in summer. This study suggests that for a better understanding of the impact and lag-time effect of climatic factors on mountain vegetation growth it is preferable to use 10-day data.