Land Prioritization: An Approach to the Effective Environmental Planning of Hydrographic Basins.

Hydrographic basins are the fundamental unit for the effective territorial planning. However, areas of higher and lesser susceptibility to degrading processes can occur in the same region, where different actions are required to preserve natural resources, as soil and water. In this context, this study aimed to propose a prioritization model to guide the territorial management in hydrographic basins. The study was conducted in the Tarumã River basin, embedded in the southwest region of the São Paulo State, Brazil. First, the basin was compartmentalized into planning units, based on the delimitation and grouping of small watersheds. In each unit, seven morphometric parameters were calculated. The relationships among the parameters were evaluated by principal component analysis, from which the parameters were weighted. It resulted in an index expressing the environmental fragility of the planning units. Among the planning units, 20% present very-high priority, only 5% very-low priority, and 75% low, moderate, and high priority. Units of higher priority are commonly at the basins' headwaters, where linear channels and steeper slopes are concentrated. Lower priority units present low relief and hydrography conditions that do not favor high-intensity erosive processes. The proposed method is effective in identifying regions of high susceptibility to degradation according to morphometric parameters, which should be prioritized on the basins' territorial management. Since these parameters can be easily calculated, it can be presumed that the results could assist the environmental planning and the optimization of natural resources management within different hydrographic basins.

Keystone Species, Forest and Landscape: A Model to Select Protected Areas.

The selection of forest fragments for conservation is usually based on spatial parameters as forest size and canopy integrity. This strategy assumes that chosen fragments present high conservation status, ensuring biodiversity and ecological functions. We argue that a well-preserved forest fragment that remains connected by the landscape structure, does not necessarily hold attributes that ensure the presence of keystone species. We also discuss that the presence of keystone species does not always mean that it has the best conditions for its occurrence and maintenance. We developed a model to select areas in forest landscapes to be prioritized for protection based on suitability curves that unify and compare spatial indicators of three categories: forest fragment quality, landscape quality, and environmental conditions for the occurrence of a keystone species. We use a case study to compare different suitability degrees for Euterpe edulis presence, considered an important functional element in Atlantic Forest (São Paulo, Brazil) landscapes and a forest resource for local people. The results show that the identification of medium or advanced stage fragments as singular indicator of forest quality does not guarantee the existence or maintenance of this keystone species. Even in some well-preserved forest fragments, connected to others and with palm presence, the reverse J-shaped distribution of the population size structure is not sustained and these forests continue to be threatened due to human disturbances.