Estratégias funcionais CSR em um gradiente luminoso em floresta urbana tropical úmida no Nordeste do Brasil

Abstract

The Atlantic Forest suffered an intense process of degradation, which transformed previously continuous environments into fragments. The CSR theory, which classifies species into competitors (C), stress-tolerant (S) and ruderals (R), has been shown to be interesting to understand the influence of the environment on the functional strategies of plant species. Thus, this research aimed to evaluate how the variation of luminosity along the ecological succession in a humid tropical forest influences the proportion of the CSR functional strategies of the trees. The work was carried out in the Dois Irmãos State Park (PEDI), which is a protected remnant of the Atlantic Forest, a refuge for fauna and flora with 1161 ha, of great importance because it is a forest within an urbanized area. Data were collected in a module of the graduate program in biology (PPBio) composed of three treatments with different ages of regeneration: younger than 30 years (initial); between 34 and 46 years old (intermediate) and over 46 years old (mature). Three 250 x 40 m plots were sampled in each treatment, which were composed of 60 sampling units of 10 x 20 m. The data were the percentage of light transmission within the canopy (TransTotal%), the basal area and three leaf functional traits (specific leaf area, leaf dry matter content and leaf area), submitted to the StrateFy spreadsheet to determine the scores. of CSR strategies. From these scores, the CWM (Community Weighted-Mean) of C, S and R of the plots was calculated to obtain the predominance of ecological strategies at the community level. A MANOVA was performed with the values of CWM-C and CWM-S, basal area and TransTotal% to detect whether environmental variables explain the adoption of functional strategies, in addition to a regression between basal area and TransTotal%, in order to assess whether the forest structure is influencing the luminosity gradient. Light did not follow the expected pattern of greater penetration in more recent regeneration and less in mature forest. The basal area followed the expected pattern, although with little influence on the luminosity gradient. In the plots with higher light input, there were more trees with S strategy and in those with lower light input with C strategy. Both light, age or basal area were not determining factors for the adoption of CSR strategies Given the history of use and exploitation in the park, anthropic disturbances and chronic disturbances may be responsible for the patterns found.