Mudanças estruturais e florísticas do estrato herbáceo-arbustivo em campo sujo e campo limpo úmido na fazenda Água Limpa-DF após sete anos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Changes in floristic composition and structure of the herbaceous and shrub layer of campo sujo and campo limpo úmido (moist grassland) at the Fazenda Água Limpa, DF were studied between September 1999 and February 2001 and between August 2006 and August 2007. For the phytosociological survey lines were randomly sampled in both areas. The first inventory was conducted in 2000, when permanent lines were installed, in an area of 400 x 400 m, divided in four portions of 200 x 200 m, where lines were randomly sampled. The line intercept method was adopted for the phytosociological survey. The second inventory was conducted from december 2006 to april 2007. In the floristic survey we sampled 509 species, distributed in 220 genera and 64 families. For the floristic survey in the campo sujo there was a reduction of 9% in the herbaceous component between the years, while the subshrubs increased 16%. For the floristic survey in the campo limpo úmido the richest families were Poaceae (35 species), Asteraceae (29), Cyperaceae (20), Melastomataceae (19) and Xyridaceae (14). In the phytosociological survey there were 253 species in 150 genera and 46 families. In the campo sujo Poaceae was the most important family, with a cover of 72,2%, similar to that found in the survey conducted in 2000. Echinolaena inflexa showed the highest frequency in both periods. Tristachya leiostachya presented the highest cover value, only in the second inventory. In the campo limpo úmido Poaceae and Cyperaceae were the most important families, with a cover of 72,2% and 34,6%, similar to that found in the survey conducted in 2000. Along the time there were significant differences between relative frequency and relative cover. The low similarity points distinct structural and floristic compositions between the campo sujo and campo limpo úmido. The substitution in the species composition suggests that the species present in the communities are undergoing changes, maybe due to lack of the frequency of disturbances. Seasonal climatic variations and fire protection for a long period is a possible explanation for the evidences of structural changes in the communities.

ASSUNTO(S)

savanna cerrado distúrbios campos botanica cerrado grassland dinâmica dynamic parcelas permanentes permanent plots fire supression

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