Herbáceas da floresta atlântica nordestina : regeneração natural em uma cronossequência de abandono agrícola e potencial invasor

• Autor(a) principal: LIMA, Patrícia Barbosa
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4581
• topic: Herbácea; Erva nativa; Ambiente antrópico; Planta invasora; Herbaceous; Native herb; Antropic environment; Invasive plant; CIENCIAS BIOLOGICAS::BOTANICA

Secondary forest areas in different successional stages are predominantly found in tropical rainforest areas, and can help with biodiversity maintenance. These forests show gradual changes in biotic and abiotic environment throughout the forest succession. The successional trajectory is well described for woody flora. Nevertheless, studies on herbaceous plants are still lagging. This study was divided into two manuscripts, whose objectives were to: 1) analyze herbaceous assembly in a 30 years chronosequence of sugar cane abandonment, and compare theses assemblade to mature forest sites, also considering environmental factors (chronosequence age, surrounding forest cover, understory light, and soil characteristics) that drive the herbs responses; and 2) understand how aliens herbaceous affect richness, and native forest herbs diversity of this chronosequence. In order to understand this, one sugar cane abandoned chronosequence was selected, containing 15 secondary forest sites (FS) (ages varying from 4 up to 30 years of abandonment), and 15 areas of mature forest (FM) in the Corredor Ecológico Pacatuba-Gargaú landscape, located inside of Paraíba Atlantic forest. In each site were established nine plots of 5x5m, in a total of 270 plots, which all herbs were registered. The plants were identified and posteriorly classified regarding their geographic origin. An NMDS was performed in order to verify difference in the floristic composition among FS and FM sites, as well as, an analysis of indicator species of those environments was performed. Generalized Linear Models (GLMs) were used to test: the impact of age areas, soil characteristics, availability of light, and surrounding forest cover on the structural characteristics of herbs in FS; and the impact of the more representative aliens herbs on native flora of FS. In a total, 42,966 individuals were registered (of this total 32,915 and 10,615 native and alien individuals, respectively), in 67 species (59 natives; 6 aliens herbs; 2 morphospecies; 66% and 18% of exclusive species in FS and FM, respectively). The density and the diversity of the herbs were significantly higher in FS than in FM, while the richness was lower in FM and the equability did not exhibit significantive difference. There was more proportion of native herbs than aliens herbs in both habitats. The floristic composition was distinct between FS and FM, also were observed 21 and 11 indicatives species of FS and FM, respectively. The sites age was positively related to richness and species diversity; however, negatively related to the herbs density. Successional progress influenced positively native richness throughout the chronosequence, and minimized negative impact of the only two invasive especies Digitaria insularis and Megathyrsus maximum on native’s species. Surrounding forest cover was also one of the mainly variants that negatively influenced richness and herbs density of the studied landscape. Finally, this study shows that despite the invasive species presence on the sugar cane abandoned chronosequence, the landscape Corredor Ecológico Pacatuba-Gargaú exhibits a dense, diverse, and rich flora of herbs (natives and alien), that are in agreement to the Intermediate Disturbance Hypothesis, and it is favored by the increment of biotic resistance associated to environmental changes along the successional progress.