Pathways affect vegetation structure and composition in the Atlantic Forest in southeastern Brazil

Abstract

Although impacts generated by gaps can aff ect vegetation, few studies have addressed these impacts in the Atlantic Forest. Our aim was to investigate the eff ects of pathways of varying widths on vegetation structure and composition, considering dispersal syndromes, diversity, life forms, successional categories and threatened and exotic species occurrence in the Atlantic Forest. We studied three pathways with widths of 2, 10 and 20 m, intersecting a protected area in southeastern Brazil. To assess edge eff ects, plots were established adjacent to paths (edge) and 35 m from the edge (neighborhood), and in a control area without pathways. Wider pathways (10 and 20 m) exhibited reduced tree height and diameter, high liana density, exotic species, and a high proportion of pioneer and anemochorous species. In conclusion, our results indicate that the vegetation structure of narrow pathways (2 m) is similar to the control area, and that wide linear gaps cause negative eff ects on vegetation and extend to a distance of at least 35 m into the forest interior. Considering that linear gaps generate permanent eff ects to vegetation and may aff ect other organisms, we suggest that these eff ects must be considered for successful management of protected areas, including planning and impact mitigation.

Association between urbanization and the biotic integrity of urban forest remnants

“…Besides, this effect changes nutrient availability in the soil and sediments' flow, as well as reduces the size of forest remnants. It is the reason why it is often impossible maintaining certain fauna and flora populations in these fragments; sometimes they even disappear from these environments (MCGARIGAL, 2015; MELLO; TOPPA; CARDOSO-LEITE, 2016;SILVA et al, 2017).…”

Is Biotic Integrity of Urban Forests Remants Related With Their Size and Shape?

“…The area "Petrochemical Terminal" (Figure 1) is relatively large (76.5 ha) and did not record high integrity. Signs of fire occurrence in the recent past have been observed in the area and this fact may justify the high rate of grasses and lianas (indicators 3, 4 (Table 1) at the edges of this fragment (Pohlman et al, 2007;Silva et al, 2017). In this area, there were few late understory and canopy species (Indicators 10 and 11, Table 1) indicating that the fire must have impaired the regeneration of late canopy species in both the canopy and understory strata.…”

“…In fact, what influences or not the biotic integrity is the presence of edges, known as "edge effect" (Murcia, 1995, Silva et al, 2017 which increases the occurrence of light and wind, and this reduces shading and moisture (Silva et al, 2007). Also, there is an increase of the presence of dead trees, clearings, lianas and grasses.…”

Área de Proteção Ambiental Rainha das Águas do município de Paraíba do Sul (RJ, Brasil): estudo da cobertura florestal, contingências e manejo

“…É possível verificar que grande parcela da área da APA Rainha das Águas apresenta pastagens, sendo essa a principal feição da paisagem que isola os fragmentos florestais. Uma pequena porcentagem do total de remanescentes florestais existentes da APA Rainha das Águas apresenta índice de circularidade próximo de 1, assim uma elevada parcela dos fragmentos florestais da APA sofre expressivo efeito de borda (Tabela 4).O aumento do efeito de borda ocorre como resultado da fragmentação das florestas, pois as condições ambientais nos trechos marginais são diferentes daqueles observados no interior dos remanescentes florestais e essas mudanças nos atributos ambientais afetam a biota presente nas bordas das florestas (SILVA et al, 2017).…”