No abstract

The clearing of native vegetation in water source areas and its effects on water supply availability have become a major concern in large metropolises. This study examined the spatial and temporal changes in land use and cover and their effects on the conservation of Atlantic Forest in a water source area in the Metropolitan Region of São Paulo that is the second most densely populated territory in Brazil, the municipality of Diadema. Historical maps and trend scenarios were developed by applying the Markov chain in association with cellular automata. Forest conservation was assessed based on a set of landscape metrics of resource availability, fragment isolation, and trends of forest fragmentation. Our findings revealed an increase in urban growth of 37% in the last five decades directly associated to the clearing of 50% of forests in intermediate/advanced stages and 40% in early stages. The main drivers of landscape change were human-modified fields (41%) and net roads (54%). Optimal resource availability was drastically reduced (75%) while isolation increased (361.5%) among existing forest fragments. Therefore, future trends indicate that, without changes in the management of the area, deforestation may occur rapidly and continuously until 10% of forest remains, leading to potential adverse effects on water availability and quality of the Billings Reservoir and the local biodiversity.

Landscape connectivity can be assessed based on the physical connection (structural connectivity) or the maintenance of flow among habitats depending on the species (functional connectivity). The lack of empirical data on the dispersal capacity of species can lead to the use of simple structural measures. Comparisons between these approaches can improve decision-making processes for the conservation or restoration of habitats in fragmented landscapes, such as the Cerrado biome. This study aimed to understand the correspondence between the measures of landscape structural and functional connectivity for Cerrado plants. Three landscapes with cerradão patches in a pasture matrix were selected for the application of these metrics based on the functional connectivity of four profiles of plant dispersal capacity. The results showed divergent interpretations between the measures of landscape structural and functional connectivity, indicating that the assessment of biodiversity conservation and landscape connectivity is dependent on the set of metrics chosen. Structurally, the studied landscapes had the same number of cerradão patches but varied in optimal resource availability, isolation, heterogeneity, and aggregation. Functional connectivity was low for all profiles (based on the integral index of connectivity—IIC) and null for species with a low dispersal capacity (based on the connectance index—CONNECT), indicating that species with a medium- to long-distance dispersal capacity may be less affected by the history of losses and fragmentation of the Cerrado in the pasture matrix. The functional connectivity metrics used allowed a more robust analysis and, apparently, better reflected reality, but the lack of empirical data on dispersal capacity and the difficulty in choosing an indicator organism can limit their use in the management and planning of conservation and restoration areas.

Question: Is there a decrease in the richness, structural variables and composition similarity of woody Cerrado species with habitat-matrix distance, potentially influenced by soil compaction and propagule dispersal strategies in the pasture matrix? Location: We studied three landscapes of a pasture matrix in areas of the Cerrado biome in southwestern São Paulo, Brazil. Methods:We sampled 110 plots of 2 m × 2 m in the matrix, stratified in ranges perpendicular to the edge of the habitat, and 10 plots in the forest with no edge effect (60 m from the edge). We undertook soil sampling and collected information about the plants (taxonomy, height, circumference and establishment form by germination or resprouting). We defined habitat distance as the predictor variable for the following response variables: abundance, richness, establishment form, mean height, mean diameter at soil height and dispersal syndrome of the individuals sampled; in addition to the porosity and bulk density of the sampled soil. Results:We found significant differences between habitat and matrix for abundance, richness, mean height and germination number, but non-significant differences for resprouting number and mean diameter at soil height. There was no relationship regarding matrix-habitat distances for structural variables, and habitat species composition was similar only for the first 10 m distance from the habitat edge. Conclusion: Pasture did not prevent plant establishment but might act as an environmental filter. Pasture matrices modify the composition and diversity of the plant community compared with the Cerrado community. Pastures are dominated by resprouting, autochory and grassland species. Regenerating plants from the propagule bank of the matrix showed the potential for natural regeneration of Cerrado areas in pasture as a restoration strategy.

No abstract