The karst landscapes offer diverse natural resources and ecosystem services. Because they
are highly fragile, these environments need integrated planning to avoid or mitigate the
environmental impacts of their occupation. To understand the structure and dynamics of
the karst landscape of the Sobrado River watershed, located in the southeast region of the
state of Tocantins, Landscape Geoecology presents itself as a theoretical and
methodological model since it analyzes the interaction between natural and social
dynamics. To this end, methodological procedures were carried out involving the
delimitation of the study area and a survey of the environmental information that
characterizes the Sobrado River watershed (BHRS, in the original acronym); preparation
of land use and land cover maps for the years 1985, 2000, 2015 and 2020; ecological
analysis with an emphasis on the results obtained by landscape metrics; geographical
analysis based on the compartmentalization of the geoecological units of the landscape,
using the overlapping of themes: geomorphology, declivity, hypsometry, geology and
soils, and subsequent association with the levels of current land use and occupation;
preparation of the exploratory map of karstic phenomena; and multitemporal analysis of
land use and land cover and fragmentation for the geoecological units with the presence
of karst features and tourist attractions. Thirty-seven geoecological units were identified
in the BHRS, with pasture being the predominant use classification in the watershed. It
was found that the geoecological units located at the top of the Serra Geral are currently
used for temporary agriculture. However, the units in the escarpment areas and near the
Serra Geral have preserved native vegetation. In the units with gentle to intermediate
relief, native vegetation areas have been converted into pastures or agriculture, followed
by the occurrence of the process of fragmentation of the remnants and a decrease in their
quality, mainly the replacement of fragments of the grassland formation and the
subdivision of fragments with an area of more than 100 hectares into those belonging to
the Savannah and Forest Formation. By overlaying the map of geoecological units with
the exploratory map of karstic phenomena, it was found that 14 units have karst features
and tourist attractions within their scope, with characteristics that portray the presence of
the Bambuí Group and the Urucuia Group, respectively, soils that are more susceptible
to the occurrence of erosive processes and the advance of human activities over native
vegetation and the fragmentation of remnants. This situation has adverse effects, such as
modifying the landscape and increasing human pressure on biodiversity and ecosystem
services. On the other hand, remnants of the Savannah and Forest Formations still
predominate, linked to massive outcrops of carbonate rocks, riparian forests, and areas
with steep terrain. The information obtained can support the implementation of
sustainable environmental planning and management to promote the rational use of
natural resource.
|
