Capim - gordura (Melinis minutiflora P. Beauv.), uma gramínea exótica que compromete a recupera??o de áreas degradadas em unidades de conserva??o

摘要

Melinis minutiflora is an African grass that invades degraded areas in the cerrado endangering native species. The effects of this invasion and of burning on Melinis minutiflora propagation were investigated in a gravel-mining pit, within the National Park of Brasilia. This study was conducted in an area where an experimental field was set up in 1993 to study the establishment of native grasses after sowing with seed mixture. Melinis minutiflora established itself in all experimental plots where castor oil cake or peat was incorporated as amendments before sowing, even though its seeds were not present in the mixture. Half of the experimental plots, which showed the highest indices of vegetation cover in May 1998, were burnt at the end of the dry season in September 1998. Eight months later, May 1999, a reduction of more than 50% in the vegetation cover of the burnt plots was recorded compared to the vegetative cover before the fire. During the subsequent years, the vegetation cover increased until it reached the pre-fire levels by May 2001. During this period, the contribution of Melinis minutiflora increased gradually to the detriment of native species, showing that burning was not effective in controlling the invasion of this alien species. Thus, it seems essential to control the invasion of Melinis minutiflora to promote the establishment of native species during recuperation of degraded patches in protected areas such as national parks.