Impacto da invasão e do manejo do capim-gordura (Melinis minutiflora) sobre a riqueza e biomassa da flora nativa do Cerrado sentido restrito

Abstract

-(Impact of invasion and management of molasses grass (Melinis minutiflora) on the native vegetation of the Brazilian Savanna). In Brazil, several grass species are cited as invaders of protected areas. However, little is known about the impacts due to establishment and colonization of these species in protected areas in Brazil. Among the exotic grasses introduced into the Cerrado the African species Melinis minutiflora P. Beauv., molasses grass, deserves special mention. The objective of this study was to evaluate the impact of this grass on the biomass and species richness of the native community in an area of invaded Cerrado as well as to study the dynamics of the vegetation of the ground layer after different management treatments for control of molasses grass. The results showed that in the experimental area, where molasses grass composed 62% of the total biomass of the ground layer, the number of native species was high. In the areas where molasses grass had a high degree of coverage (> 98%) its biomass was approximately two times higher than values cited in other studies in the Cerrado. Between three and four years after using fire as a management tool for control of molasses grass its biomass returned to values similar to those observed prior to this treatment. Contrarily, with an integrated management treatment (May or September) a reduction of 99.9% in the presence of molasses grass was observed along with a recovery of native vegetation, making this a promising strategy for recuperation of areas in the Cerrado that were invaded by molasses grass.Key words -biological invasions, conservation, restoration RESUMO -(Impacto da invasão e do manejo do capim-gordura (Melinis minutiflora) sobre a riqueza e biomassa da flora nativa do Cerrado sentido restrito). No Brasil, várias espécies de gramíneas são citadas como invasoras em Unidades de Conservação. Contudo, ainda se conhece muito pouco sobre o impacto do estabelecimento e da colonização dessas espécies nas áreas protegidas. Entre as gramíneas exóticas introduzidas no bioma Cerrado merece destaque a espécie africana Melinis minutiflora P. Beauv., o capim-gordura. O presente estudo objetivou avaliar o impacto desta invasora na biomassa e na riqueza da comunidade nativa em uma área de Cerrado Ralo invadido, como também estudar a dinâmica da vegetação do estrato rasteiro submetida à aplicação de diferentes técnicas de manejo para o controle do capim-gordura. Os resultados mostraram que, na área experimental, onde o capimgordura representa cerca 62% da biomassa total do estrato rasteiro, o número de espécies nativas encontradas foi alto. Nas áreas onde o capim-gordura apresentou alto índice de colonização (> 98%), sua biomassa alcançou cerca de duas vezes a biomassa do estrato rasteiro registrada para o Cerrado. A realização de uma queimada não foi suficiente para controlar o capim-gordura, porque após três anos a sua biomassa se aproximou aos valores encontrados inicialmente. Por outro lado, no tratamento manejo integrado (maio ou setembro) a reduçã...

Impact of invasion by molasses grass (Melinis minutifloraP. Beauv.) on native species and on fires in areas of campo-cerrado in Brazil

“…Molasses grass greatly increased the fine fuel biomass in the campo-cerrado areas of the PESRM, potentially reaching values of up to 18 Mg/ha, similar to the 12.1-21.4 Mg/ha estimated for a cerrado area with high rates of invasion in Brasília (Martins et al, 2011). The negative correlation between the biomasses of native monocots and those of molasses grass suggests that the former have been suppressed by the latter.…”

“…occur in Brazil (Biodiversitas et al 2006;Filgueiras et al 2010). Molasses grass grows vigorously in the nutrient-poor and aluminum-rich soils of the Cerrado Biome (Gonçalves & Borges 2006;Martins et al 2011). It blooms at the beginning of the dry season, in mid-May, producing large amount of seeds with a germination rate of approximately 90% (Alcântara & Bufarah 1951;Martins 2006;).…”

Rehabilitation of degraded dryland ecosystems – review

“…However, alien invasive plants are not always a menace, as observed in the Cerrado vegetation where the alien grass Melinis minutiflora P. Beauv. increased the above-ground biomass by 40% within two-year period (Martins et al 2011). The degradation of rangelands is further complicated by rangeland conservation policies, such as exclusion of grazing, the ban on traditional burning practice and tenure insecurity, which are proven to bring no additional benefits but rather exacerbate the degradation process (Solomon et al 2007;Savadogo et al 2008;Angassa et al 2012).…”

Floristic composition of a Neotropical inselberg from Espírito Santo state, Brazil: an important area for conservation

“…The biological invasion process has been responsible for significant changes in the structure and composition of vegetation in diverse ecosystems around the world (D' Antonio & Vitousek 1992;McNeely et al 2001). In particular, the African grass Melinis minutiflora is an extremely aggressive invasive, competing successfully with native flora, being found in many Brazilian protected areas, where it can disfigure the original phytophysiognomy in a few years (Martins et al 2007(Martins et al , 2011. In addition, worth mentioning the large accumulation of biomass fuel, which aggravates vulnerability to fire, because it alters characteristics of the fire regime of invaded areas (D'Antonio & Vitousek 1992).The high number of endangered species occurring in the studied inselberg and presence of invasive species reinforces the need for conservation initiatives in the area.…”