Forest land cover phenologies and their relation to climatic variables in a Carpathian Mountains region

摘要

Sustaining forest resources in Romania requires a better understanding of forest ecosystem processes, and how management decisions and climate and anthropogenic change may affect these processes in the future. This paper aims to provide an application of time series anomalies and harmonic analysis to extract information about vegetation phenology from NDVI/EVI and LAI time series for a forest ecosystem Prahova Valley, placed in Carpathian Mountains, Romania, from MODIS Terra/Aqua data over 2000 - 2017 period. Spatio-temporal forest vegetation dynamics have been quantified also based on LANDSAT TM/ETM/OLI satellite data. Several daily climatic variables, were used as explanatory variables for the discussion of the vegetation phenology behavior. For investigated test area, considerable NDVI/EVI and LAI decline were observed for drought events during 2003, 2007, and 2012 years. The vegetation phenology analysis was correlated with associated time series of climatic variables in order to detect recorded anomalies. Temperature, rainfall and radiation were significantly correlated with almost all forest land-cover classes, while vegetation phenology was not correlated with climatic variables for the same period of analysis, suggesting a delay between climatic biophysical parameters variations and forest vegetation response. Under stress conditions, it is evident that environmental factors such as soil type, parent material, and topography are not correlated with NDVI/EVI dynamics.