Desenvolvimento tecnológico em bioengenharia de solos aplicável em programas de restauração ecológica

Abstract

The restoration of degraded areas consists in creating conditions to repair part of the ecological functions of an ecosystem that has lost its resilience. In sites where the natural regeneration capacity has been lost, human intervention is fundamental for the establishment of environmental conditions that favor the natural recovery process. In order to contribute with innovation of environmental restoration methods of opened gaps to hydrocarbons prospection in the amazon biome, the objective of this study was to provide the use of macro cuttings of pioneer species associated with prefabricated and biodegradable structures for contention of surface erosion. The study of vegetative propagation was developed for eleven native species, in forest nursery outdoors under sprinkler irrigation system located in Manaus, Amazonas, Brazil (03005 32.2 S e 60001 08.1 W). Ninety cuttings for each species were tested by planting in polyethylene containers with sand substrate, as initial establishment. Experimental was completely randomized design. Thirty cuttings for each species were excavated after 60, 90 and 120 days of the experimental installation. It was done using a water jet in low pressure and the goal was to quantify the survival rate. On each cutting was verified the number and base diameter of shoots, the length of the longest root and shoots and dry mass of shoots and roots. Only Alchornea castaneifolia, Salix humboldtiana and Piper aduncum species among all tested presented vegetative development, with a survival rate between 70 and 100%. Multivariate analysis of variance (MANOVA) detected difference among three species. Although these species presented fasciculate root system, S. Humbolditiana developed roots in all cutting extension, in Alchornea the roots are localized in the base of the cutting and in P. aduncum they are concentrated in nodes below the soil. Simple linear regression analysis demonstrated that cuttings amplitude range from 1 to 3,5 cm has influence only in the number of shoots at 120 days to P. aduncum, not interfering in other variables of growth of shoots and roots. The retainers of surface erosion were produced with three different types of particles (coconut fiber, buriti straw and chopped wood), two adhesives (centrifuged latex and polyvinylacetate - PVA) and in three different shapes (trapezium, rectangular and grid), resulting in 11 treatments. The two treatments that used polyvinylacetate as an adhesive did not confer enough resistance to the structures and those were deformed by the increase of the volume after 24 hours of water immersion. The nine treatments that used latex were similar in response to water absorption. However they were different in swellingand maximum force to break. Only the structures made by using coconut fiber or chopped wood and latex as adhesives demonstrated to be viable to a large scale production. We suggest that assays in field with these structures and plant cuttings are be made to verify their efficiency when submitted to all environmental conditions.