Florística e estrutura em cronossequência de florestas pós-abandono da cultura do café na Mata Atlântica

Abstract

In the state of Espírito Santo, the Atlantic Forest vegetation was severely impacted and, currently, around 12% of its original coverage remains. The original forests were replaced by agricultural crops, mainly coffee, which in the mountainous region of Espírito Santo, is present on more than 65% of rural properties. In many cases, the forests that still persist on rural properties are the result of the natural succession process that occurred after the abandonment of coffee plantations. However, little is known about the flora and structure of these forests. Given the above, this study aimed to characterize the structure and floristic composition of the arboreal component of a chronosequence of secondary montane forests post-abandonment of coffee cultivation in the southern region of Espírito Santo. Three forest areas with different ages were selected, two established after the abandonment of coffee cultivation (A20 and A50), and one area of mature forest with no history of clear cutting (Aref), located in the municipality of Venda Nova do Imigrante. At each location, ten plots measuring 10 m x 10 m (1000 m².area-1) were implemented, totaling 30 sampling units (3000 m² of total area). In each plot, all tree individuals, palm trees and tree ferns with a diameter at breast height (DBH) equal to or greater than 5 cm were sampled. The individuals were numbered and their dendrometric data (DBH and height) were estimated. Plant samples were collected for identification and collection in the herbarium. The phytosociological parameters, Shannon's diversity index and Pielou's evenness index were calculated, as well as the similarity index. The floristic composition was classified according to functional group (diversity and coverage), dispersal syndromes (anemochory, zoochory and autochory) and IUCN threat categories (Critically Endangered: CR, Endangered: EN, and Vulnerable: VU). Overall, 366 individuals were sampled, from 40 families, 126 species and 79 genera (57 individuals, 13 families, 22 species, and 19 genera in A20; 133 individuals, 23 families, 48 species and 38 genera in A50; 176 individuals, 28 families, 56 species and 46 genera for Aref). The predominant dispersal syndrome, in all sampled areas, was zoochoric. In total, five species appear on the official lists of endangered species, with three species classified in the VU category, one cited as CR and one cited in the EN category. In addition to these, species with deficient data (DD) were mentioned. In relation to the functional group, the predominance of species classified as diversity was observed in the three areas. Similar richness patterns were detected between the 50-year and reference areas, with no differences observed by sample-based rarefaction and extrapolation curves. However, the species richness curve showed marked changes between areas. For example between the 50-year and reference areas the richness curve is similar and differs with the 20-year area, with contrasting differences in shared species. Regarding abundance in the areas, there was a greater number of individuals in Aref, with lower abundance recorded in A20. The most abundant species in A20 were Piptadenia gonoacantha (Mart.) J.F.Macbr. (8 ind.) and Ocotea cf. aurantiodora (Ruiz & Pav.) Mez (7 in.). For A50, the species with the greatest abundance were Casearia sp. (17 ind.), Euterpe edulis Mart. (10) and for Aref, they were E. edulis (18 ind.) and Aparisthmium cordatum (A.Juss.) Baill. (11). Despite presenting different ages, only the 20-year-old area proved to be very different from the other two areas studied, with greater similarity between areas A50 and Aref. With the results presented in this study, we can expand our knowledge of the flora of Espírito Santo. Attention is drawn to secondary forests, which are extremely important, as they are able to preserve floristic groups, with a considerable richness of species, including rare or endangered species, thus conserving the remnants of the Atlantic Forest and helping to recover its native vegetation.