Effect of drainage ditches on diversity, structure and dynamics vegetation in campos de murundus (mound fields)

Abstract

Campos de murundus (CM) is a savanna vegetation type of Cerrado which remain flooded in the rainy season. It is considered protected areas in the state of Goiás, Brazil, but are under strong pressure due to the construction of drainage ditches around them. In this study we compared sampled and estimated species richness, structure and vegetation dynamics between drained and non-drained areas in CM over a seven-year period. We delimited 10 20x50 m plots in drained areas and 10 plots in non-drained areas with 200 m between them. Friedman's test was used to compare richness and individuals per plot between drained and non-drained areas. A MANOVA was used to compare horizontal structure parameters such as density, frequency, dominance, importance value index, importance value cover, mortality, recruitment, net changes and turnover in individuals and basal area per plot between areas. The estimated richness was higher in non-drained than in drained areas. Density and absolute dominance were greater in drained than non-drained areas. The increase in species richness, individual number, densification, dominance, and recruitment of individuals indicates encroachment of woody plants in the mound fields over time in both areas. Our study suggests a shift on structure of woody layer in CM which may affect ecosystem services such as water circulation in the long term.