RESUMO
The Brazilian Cerrado is a hotspot of biodiversity conservation and an important global agricultural region. Cultivated pastures under different degradation levels are dominant in the landscape and are being targeted for sustainable agricultural intensification and restoration of native vegetation. In this study, we classified the cultivated pastures of the Brazilian Cerrado according to their potential for natural regeneration, based on field surveys and environmental predictors. We surveyed the native vegetation cover in 186 plots distributed along 93 cultivated pastures. The environmental predictors considered in this study were the proportion of sand in the soil, cation exchange capacity, climate water deficit, pasture age, slope, and pasture vigor index. We then applied the Random Forest regression algorithm to predict and map the cultivated pastures according to their potential for natural regeneration in the 19 Cerrado ecoregions. The potential for natural regeneration was classified into low (< 30% of native plant cover), medium (30-50%), and high (> 50%). Our prediction explained 75% of the data variability. Most of the cultivated pastures presented medium potential for natural regeneration (57%), while 31% and 12% presented high and low potentials, respectively. Cultivated pastures in ecoregions with high mechanization, due to their high water availability and extensive flat terrains, presented low potential for natural regeneration. This first attempt to map the potential for natural regeneration in the cultivated pastures of the Brazilian Cerrado can be used as a proxy for planning low-cost and predictable restoration or environmentally sustainable intensification in this major type of land use found in this biome.
Assuntos
Conservação dos Recursos Naturais , Monitoramento Ambiental , Brasil , Ecossistema , Biodiversidade , Agricultura , ÁguaRESUMO
Degraded pasture is a major liability in Brazilian agriculture, but restoration and recovery efforts could turn this area into a new frontier to both agricultural yield expansion and forest restoration. Currently, rural properties with larger degraded pasture areas are associated with higher levels of technical inefficiency in Brazil. The recovery of 12 million ha of degraded pastures could generate an additional production of 17.7 million bovines while reducing the need for new agricultural land. Regional identification of degraded pastures would facilitate the targeting of agricultural extension and advisory services and rural credit efforts aimed at fostering pasture recovery. Since only 1% of Brazilian municipalities contain 25% of degraded pastures, focusing pasture recovery efforts on this small group of municipalities could generate considerable benefits. More efficient allocation of degraded and native pastures for meat production and forest restoration could provide land enough to fully comply with its Forest Code requirements, while adding 9 million heads to the cattle inventory. Degraded pasture recovery and restoration is a win-win strategy that could boost livestock husbandry and avoid deforestation in Brazil and has to be the priority strategy of agribusiness sector.
RESUMO
Edge effects alter insect biodiversity in several ways. However, we still have a limited understanding on simultaneous responses of ecological populations and assemblages to ecotones, especially in human modified landscapes. We analyze edge effects on dung beetle populations and assemblages between livestock pastures and native temperate forests (Juniperus and pine-oak forests (POFs)) to describe how species abundances and assemblage parameters respond to edge effects through gradients in forest-pasture ecotones. In Juniperus forest 13 species avoided the ecotones: six species showed greater abundance in forest interior and seven in pasturelands, while the other two species had a neutral response to the edge. In a different way, in POF we found five species avoiding the edge (four with greater abundance in pastures and only one in forest), two species had a neutral response, and two showed a unimodal pattern of abundance near to the edge. At the assemblage level edge effects are masked, as species richness, diversity, functional richness, functional evenness, and compositional incidence dissimilarity did not vary along forest-pasture ecotones. However, total abundance and functional divergence showed higher values in pastures in one of the two sampling localities. Also, assemblage similarity based on species' abundance showed a peak near to the edge in POF. We propose that conservation efforts in human-managed landscapes should focus on mitigating current and delayed edge effects. Ecotone management will be crucial in livestock dominated landscapes to conserve regional biodiversity and the environmental services carried out by dung beetles.