Caracterização química de frutos carnosos de acordo com um gradiente ambiental rural-urbano: implicações para as aves frugívoras

Abstract

Urban afforestation reduces the impact of urbanization on biodiversity, e.g., by offering fruits to birds. As the urban area is generally polluted due to vehicles traveling, it is worth questioning whether the chemical properties of the fruits are altered due to pollution, and the frugivorous birds are expected to do harm in a nutritional perspective. Here, some chemical properties of fleshy fruits in the urban area are investigated to ascertain their nutritional quality and potential negative impact on frugivorous birds. The chemical properties were evaluated in a comparative perspective, i.e., urban (polluted) and rural (presumed unpolluted) environment. For this, 500g of ripe fruits from different plants (5/species/environment) were collected from Ficus benjamina (fig-benjamina), Mangifera indica (mango), Morus nigra (mulberry), Psidium guajava (guava) and Syzygium cumini (jambangly). Using multiple methods, the following nutritional parameters were analyzed in the laboratory: pH; Soluble solids; Titratable acidity; Total Reducing Sugars; Vitamin C; Pigments; Total Phenols; Antioxidant Capacity. Possible changes in these properties according to the environmental gradient were analyzed using the Mann-Whitney U Test. The consumption of fruits by birds was observed in the respective plants, therefore environments. The chemical properties of the fruits were shown to be contrasting in relation to plant species and environments, with no pattern of changes. Some chemical parameters increased or decreased in the urban environment compared to the rural one. For example, the pH value obtained from M. nigra fruits was significantly higher in the rural environment. In S. cumini, it was higher in the urban area. Thirty-two species of birds consumed fruits of the aforementioned plant species, a total of 1134 observations, 323 in the rural area and 811 in the urban area. Chemical properties varied diffusely according to the rural-urban environmental gradient. However, some quality parameters based on these properties are, in general, similar between such environments. The level of fruit consumption in the urban environment is considerable, possibly due to vitamin and antioxidant levels, which were higher in this environment. Therefore, potential nutritional problems arising from this activity of frugivores must be interpreted with caution. Due to the contrasts in the chemical properties of the fruits considering the plant species and the rural and urban environments, it is healthy to include other analyzes and thus identify more significant chemical changes that can affect the nutrition of avifauna via frugivory in the urban area.