Distúrbios climáticos do antropoceno afetam negativamente o manejo florestal na Caatinga: estudo de caso com Amburana cearensis (Allemão) A.C.Sm

Abstract

The main climate variables that show a tendency to change due to global warming are: the frequency of ENSO events, precipitation, and the average temperature of the planet. The last two factors are strongly correlated with the annual increment of plant biomass. All of these parameters point towards negative trends for plant growth in tropical zones in the short and medium term, including in the semi-arid region of the Brazilian Northeast. Understanding the effects of climate fluctuations on Caatinga trees will help in decision-making aimed to mitigate the combined action of climate and anthropogenic disturbances on the sustainability of forest management. Management methods such as coppicing are traditionally applied to accelerate the increase of biomass in forest systems. However, long-term studies to verify the effect of climate change on forest management demand time and money. Alternatively, investigations through dendrochronology are effective in detecting relationships between climate and tree growth. In aforementioned, we aim to understand, through dendrochronology, the effects of climate disturbances on the growth of natural populations of non-coppice vs. coppice trees of Amburana cearensis in the Caatinga of the state of Ceará, one of the driest areas in the Brazilian Northeast. We found a strong negative correlation between the SST of the eastern equatorial Pacific Ocean (a region associated with ENSO phenomena) and the maximum terrestrial temperature in the study area with the growth of the studied species. There was a strong positive correlation between precipitation in the study area and the increment of tree biomass. The growth of individuals grown from coppice was faster than that of non-coppice individuals. The fact that both coppice and non-coppice trees demonstrate climate sensitivity in the annual increment of biomass reflects how vulnerable the natural populations of this species are to the ongoing climate changes in the Brazilian semi-arid region. This also allows us to infer that the acceleration of growth caused by coppice in commercial forests extends to the application in the sustainable management of natural populations of the Caatinga. The dendrochronology of coppice and non-coppice trees can also support the definition of more updated management plans, since the annual diametric growth will depend on the frequency of El Niño events, which tend to increase, harming plant growth. Both coppice and non-coppice populations will be negatively affected by climate change, which will affect most of the species distribution range.