Semeadura direta para restauração florestal e seus efeitos sobre comunidades de formigas e interações ecológicas

Abstract

The conversion of natural habitats into degraded areas poses a great threat to biodiversity. This process makes restoration practices increasingly necessary to help ecosystems reach a condition with greater functional complexity over time. Active methods such as direct seeding are used to accelerate the restoration process in structural vegetation recovery, fauna restructuring and ecological processes. We carried out the study in pasture areas, in a contact zone Savana/Forestry Seasonal. We implemented sowing experiments divided into three parts: broadcast, lines and control. We subdivided sowing plots into two: partial composition of green manure species and complete composition with the same species and adding more agricultural species. Control plots were prepared but not seeded. We used four successional classes with a total of 57 sown species. We evaluated the effect of different types of sowing on the successful establishment of native tree species and on the decrease in exotic grass over three years. Plants from the 1-year successional class covered 33 to 89% of the soil at three months and were replaced by the 2-4 year class, covering 41 to 95%. At 36 months the 1 year class no longer covered, the 2-4 year class coverage decreased from 15 to 75%, the 5-10 year class covered 38% and the >10 class had low cover due to slow plant growth. There were large variations in establishment between species and in their responses to treatments and sampling times. Exotic grasses recolonized but shared the cover with the sown species, which was greater in absolute terms. However, exotic grass decreased the density of tree seedlings. On the other hand, the coverage of the initial classes resulted in a higher density of tree seedlings. Our best treatment, partial-broadcast, with 5-10 year old tree cover reaching 30% and a density of 20.000 seedlings/m2 of class >10 years at 36 months, we consider the restoration to be successful without chemical maintenance or mechanics. These areas already form dense and stratified patches of capoeira, increasing the initial vegetation structure, which can trigger and favor the restructuring of the fauna and the return of ecological processes that are important for the community's dynamics. We compared ant diversity and seed and herbivory removal rates in sowing areas, with seedlings of the same age planted and pasture as control. We found differences in richness and relative abundance, reflecting similarity in terms of composition. We also saw that seed removal was higher in sowing areas, with an increase of 20% compared to planting seedlings and 31% compared to pastures. Herbivory rates were low and did not differentiate between areas, but varied between species. Our results indicate that the largest vegetation structure achieved by the direct seeding method can be effective in recovering ant diversity, modifying the animal-plant interaction networks, with results that can be favorable for community recovery throughout the succession.