Effects of forest succession on the richness and composition of Zingiberales in a forest fragment in the southwestern Amazon

Tropical forests have been increasingly modified by human activities and the forest recovery through succession has caused an increase in the amount of secondary forests in the landscape. Little is known about changes in the richness and composition of non-woody species throughout the succession in tropical forests; therefore, the objective of this work was to evaluate the effects of forest succession on a community of herbs in the order Zingiberales. Zingiberales and soil were sampled and data on vegetation structure, including bamboo abundance, canopy opening, and basal area were collected from nine 80 × 90 m plots installed on the Catuaba Experimental Farm, Acre, representing three successional stages: early secondary forest, late secondary forest, and mature forest. Early secondary forest areas were experimentally deforested, burned, and sprayed with herbicide in the dry season of 2001 and the late secondary forest areas suffered deforestation followed by burning for agricultural cultivation between 1985 and 1986. A total of 3,831 individuals and 26 species distributed in nine genera and five families was registered. Both soil characteristics and vegetation structure variables showed significant differences among the successional stages. The richness of Zingiberales was lower in the early secondary forest areas and did not differ among the other successional stages. Canopy opening was the variable that best explained the variation in the richness of Zingiberales among the areas. The composition of Zingiberales differed among the successional stages, with the late secondary forest and mature forest stages being most similar. The soil characteristics, canopy opening, bamboo abundance and basal area were the variables that best explained a variation in the composition of Zingiberales. In the areas of initial secondary forest the group of dominant species was composed of Renealmia breviscapa , Calathea altissima and Heliconia rostrata , in the areas of late secondary forest by Chamaecostus lanceolatus Calathea polytricha , Calathea sp.1 and in the areas of mature forest by Heliconia acuminata, Calathea mansonis and Phenakospermum guyannense . These results show that the disturbance caused by cutting, burning, and herbicide application alters the community of Zingiberales. These data also highlight the importance of late secondary and mature forests in maintaining and recovering biodiversity.