Espécies invasoras em sítios de restauração florestal de floresta estacional

Jézili Dias

Exotic invasive species are the second greatest cause of biodiversity loss in the world. In forest restoration, these invaders can cause serious problems, like the suppression or exclusion of plants through competition and changes in the environment. Among these species, tropical invasive grasses are responsible for heavy costs and contribute to several setbacks. Given these issues, this study aimed to evaluate the effects of preexistent nonnative species on forest restoration in semideciduous Atlantic Forest. To check for the effect of invasive plants, we installed 120 plots (10x10m), divided into 12 native species reforestation sites aged from 40 to 89 months. Four subplots (1m²) per plot were installed to estimate herb dry biomass. Grass abundance declined with age of the sites (n=12; β=-0,61; p=0,03; r²=0,37) and with the percentage of planted pioneer trees (Spearman, r=-0,61). Abundance and biomass of non-grass ruderal species showed a positive relationship with canopy openness (n=12; β=0,58; p=0,04; r²=0,34 e n=12; β=0,57; p=0,05; r²=0,33 respectively). Soil fertility and grass biomass were positively related, markedly due to K+ concentration (Spearman, r=0,60) and grasses abundance increased with the P concentration (Spearman, r=0,62). Grass abundance declined with age of the areas, but grass biomass was not explained nor by age or by canopy openness Panicum maximum Jacq. (guinea grass) and the native regeneration was affected negatively by this grass. The results suggest that, while some grasses show strong detrimental effects on the regeneration, non-grass ruderal species are not necessarily a concern.

Espécies invasoras em sítios de restauração florestal de floresta estacional

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