Soil and vegetation types are predisposition factors controlling greenness changes: A shift of paradigm in greening and browning modelling?

Abstract

Increases (greening) and losses (browning) of vegetation greenness related to climatic and anthropic changes are processes well documented in the literature. However, the control exerted by predisposition factors on the response of vegetation to these changes has been little studied, and appears to be especially important in anthropized regions. The present study aimed to map greening and browning processes, as well as to characterize and analyze their distribution in heavily anthropized regions regarding two main predisposition factors: soil and vegetation types. The Brazilian Semiarid region was used as a model area, using two novel approaches: a readily reproducible cloud computing approach to map consistent greening and browning processes, and a disaggregation approach in homogeneous units of vegetation, soil and land use types. The results showed that stable greenness dominates (66.8%), but browning is more frequent (29.1%) and intense than greening (4.1%), and may be related to desertification processes in native and anthropized areas. The distribution of greening and browning processes is zonal and heterogeneous. Environmental predisposition factors, mainly the water supply capacity, regionally control the distribution of greening and browning zones. Human-environment interplays locally regulate the intensity and distribution of the processes. We defend the need of a paradigm shift in greening and browning modelling. Further studies should consider the simultaneous and balanced use of predictors related to both predisposition and changes. The need for advances in the interpretability of these models is also evident, given that current approaches fail to elucidate the regulating mechanisms of greening and browning processes.