Estudos de espécies de topsoil de campo rupestre ferruginoso potenciais para recuperação de áreas mineradas

Abstract

The modern society has a growing demand for iron ore, generating economic, social and environmental impacts. Mining activities licensing requires compliance with a broad environmental legislation that establishes guidelines for recovering, revegetating and rehabilitating exploited areas. Associated with iron ore deposits are the Ferruginous rocky fields, an environment rich in diversity and plant endemism. Due to the vegetation specificity, which is still little studied, in addition to the lack of seedlings and seeds of its species in the market, the recovery and even the rehabilitation of these environments are challenging. One of the alternatives to obtain biological material able to revegetate these slopes, cuts and landfills of the mined areas is to use the species that have developed from the topsoil seed bank of that site. Against the foregoing, this study’s objectives were to evaluate the species from the ferruginous topsoil seed bank deposited in the Research and Innovation Unit of the Ferruginous rocky fields, located in OuroBranco - MG and to select the grass with the highest importance value index (IVI). In the analysis, absolute and relative density, frequency and coverage parameters were calculated in addition to IVI for all species, identifying 430 individuals from 42 species, distributed in 12 families, being the Poaceae family the most important and the Eragrostispolytricha, because of its higher IVI, was identified as the potential species to be used in revegetation and recovery of degraded areas. Through the result obtained, seeds of the Eragrostispolytricha species were collected, stored and benefited with the objectives of evaluating the presence of dormancy, characterizing their germination, evaluating the effect of different treatments on germination and determining the temperature and regime conditions to conduct the germination test. The treatments consisted of four replicates of 50 seeds each. Germination tests were performed using alternating temperatures of 15-35ºC, 25ºC and 35ºC constants, also soaked in 0.2% KNO3 solution. In the germination tests, the treatment with alternating temperature (15-35ºC) using KNO₃ obtained the best result with 95.5% of germination. It was also compared the test of alternating temperature germination 20-30ºC using KNO3 in seeds without bark and with bark, which did not present significant difference. It was concluded that the high percentages of germination of this species and the speed with which the seeds germinate under more favorable conditions suggest that Eragrostispolytricha is a species that is potentially suitable for the recovery of degraded areas.