Environmental influences in the annual current increment of the basal area, in the Caatinga environment

Influências ambientais no incremento anual da área basal, em ambiente de Caatinga

ABSTRACT

The growth of plant species is directly influenced by biotic and abiotic factors. With this, the objective was to identify variables that influence the current annual increment – CAI of the basal area, in two areas, considered as “least conserved” and “most conserved” in the Semiarid of Pernambuco, Brazil. The dendrometric data is from 40 permanent plots of (20 m x 20 m), in the years (2008 and 2011 to 2019), measurements were conducted on individuals and branches with a circumference at 1.30 m from the ground ≥ 6 cm. The environmental data came from the National Institute of Meteorology and the Water and Climate Agency of Pernambuco. Spearman's correlation was applied between the CAI and the environmental variables, given the problem of repeated measurements, the mixed linear regression model was used: CAI_i = (β₀ + α_period + λ_specie) + β_nVdendrometric_n + β_mVenvironmental_m + ϵ_i, considering the random effects the period and species, and the fixed effects the dendrometric and environmental variables. Regarding the significance of the variables in the CAI, an influence was noted for the least conserved area only in relation to the fixed effects, whereas in the most conserved area it was significant in terms of the fixed effects for the dendrometric variables. In general, the model showed satisfactory performance, residual distributions, without outliers. Despite having shown influence of environmental variables only in the least conserved, long-term monitoring is necessary, to overcome seasonal drought events.

Keywords
Seasonally dry tropical forest; Growth; Climate conditions