Fenologia reprodutiva da comunidade vegetal em ecossistemas de veredas no Sudeste do Brasil

Abstract

Veredas are flooded ecosystems in the Cerrado, ecologically important and highly threatened. The description of the reproductive phenological pattern of the plant community in these environments and the evaluation of the influence of abiotic factors on flowering and fruiting of its species can help to understand the ability of plants to reproduce and adapt to various environmental variations. We followed the reproductive phenology of the plant community of two veredas, under different soil water conditions and landscape changes, to answer: (i) is the reproductive phenological pattern related to seasonality? (ii) does the reproductive phenological pattern differ between the two distinct microenvironments of the veredas (open area and hygrophilous forest)? (iii) does the phenological reproductive pattern differ between the two veredas in relation to soil moisture and landscape modification? (iv) which of the environmental variables tested (temperature, precipitation, photoperiod and water table level) affects or influences flowering and fruiting in these ecosystems? The study was developed in the Almescla Footpath, in the Pandeiros River Environmental Protection Area (APA Rio Pandeiros), in Bonito de Minas and in the Peruaçu Footpath, in the Veredas do Peruaçu State Park, in Cônego Marinho, northern Minas Gerais State. A total of 91 species (36 families) were monitored, from a phytosociological study conducted in the Almescla and Peruaçu veredas in 2017. Phenological observations were carried out monthly, during 36 months, in the Almescla vereda, from March 2018 to February 2021 and during 24 months in the Peruaçu vereda, from August 2018 to July 2020. During the monitoring, the presence or absence of the reproductive phenophases of flowering (emergence of floral buds and open flowers) and fruiting (immature and mature fruits) were recorded for all species studied. To evaluate the seasonality of the reproductive phenophases, circular statistical analyses were performed. The determination of the influence of climatic and environmental variables, was made from multiple regressions. Despite the absence of seasonality effect, there is a relationship of the reproductive phenology of the Almescla and Peruaçu vereda with the rainy season and the dry season, respectively. A divergent phenological pattern was observed between the microenvironments of open area and hygrophilous forest and between the veredas, which are under the same climatic conditions, but with different hydric conditions and landscape structure. Among the environmental variables tested, the temperature showed more correlations with the phenophases, but with the lowest values. The highest correlations observed were of the flowering of the species with the water table level. The seasonal climate is considered the main factor capable of defining the phenological patterns of the Cerrado vegetation, resulting in a wide diversity of phenological strategies. The decrease in water table levels in the Peruaçu vereda, which has caused the drying of this ecosystem, is the main cause of landscape modification, which leads to the colonization of species from drier environments and consequently, changes in phenological patterns of this environment.