Physical Environment Aspects as Subsidy to Occupation in Southwest Amazon Conservation Units – A Case Study Relating the Jamari National Forest and its Surrounding Areas

Abstract

This research had as its objective the understanding of physical environment dynamics and its association with land occupation in the Jamari National Forest and its surrounding areas. Geoprocessing and the adaptation of thematic maps were used during the research. Field activities were carried out in order to verify the adapted maps, interpret the actual land occupation dynamics and to collect and analyze soil/sediment samples. Most of the soils were shown to be physically fragile with low nutrients bioavailabile. They cannot support agricultural activities, even with the use of fertilizers. Research showed the presence of soils with a high content of sand fraction grains, presenting high levels of quartz mineral, which vary from 76 to 93% in the west, where the greatest anthrop interference in the area can be found. Cattle rearing is the prevailing activity in the region. This occupies around 95% of deforested areas. The pastures have lost approximately half of their productive biomass capacity in 10 years forcing either the clearing of previously forested areas or the acquisition of lands by cattle ranchers. The settlers that sell their lands purchase others that are cheaper, forested, so continuing the cycle of settlement and clearance. However, research shows that the fine balance between vegetation, soil and dissected relief is fragile. Thus, the breaking of this balance by altering any of these elements can accelerate the erosion process and nutrient loss to the depth of the water table. The structural and mineralogical characteristics of the soils show marked limitations for agricultural use due to the reduced volume of weathered material available to physically support crop cultivation and humidity retention.