Regeneration dynamics of the Baetic Spanish fir forests. Inter-annual and seasonal trends analysis of NDVI

Abstract

The Spanish fir is a botanical relic of the Tertiary that persists in a singular mountain ecosystem. This fir is an endemic species that is unusual in the Andalusian landscape, so it is strongly protected with a pro-active conservation management that seeks to mitigate the negative effects of global change. In this paper, we analysed the Spanish fir forests based on time series analysis of 15 years of MODIS images. First, we generated a monthly frequency series of 180 images, from January 2002 to December 2016, and then we applied an interannual and seasonal trend analysis by using monthly average of NDVI. The results showed positive trends of NDVI in the Spanish fir forests. The trend was significant in almost all types of tree cover density and forest types of Spanish fir. This suggests that the current pro-active conservation management program favours the regeneration of these forests. However, we found an earlier start of Green up, that could be related to global warming.