Pastagens no cerrado e a rela??o com os t?rmitas construtores de ninhos ep?geos

• Autor(a) principal: Lima, Sandra Santana de
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/3636
• topic: Isoptera; Indicadores; Cupinzeiros; Isoptera; Indicators; Termite mounds; Agronomia

The presence of epigean termite nests in pastures is commonly associated with degradation. Although there is no consensus about the damage caused by these insect builders, the presence of epigeous nests in pastures has been considered as a sign of degradation, reduces the value due to the pasture appearance, and at high density could reduce the area for grazing. This study evaluated the diversity and population of termites with pasture declining productivity and quality in the Brazilian Cerrado region. The survey was conducted on farms in the municipalities of Rio Brilhante and Anauril?ndia, both in Mato Grosso do Sul State. Pasture areas were selected and demarcated with different amounts of termite nests. In Chapter I, conducted in both municipalities, termites were collected for ?15N and ?13C analyses. The termite nests were evaluated in relation to number per hectare; area occupied; activity and spatial distribution of mounds. There were identified 14 species, where Cornitermes cumulans, which is a litter consumer, was the most commonly observed. The ?13C analysis of the termites indicated that forage grass of brachiaria grass was the sole food source. Different 15N values were registered between groups of humivours (between 13 and 15 ?), intermediate (11 ?) and litter-eaters (2 to 5 ?). The area occupied by the nests (0.26 to 1%) did not affect the pasture net area, and the nests spatial distribution was random. In Chapter II, conducted in Rio Brilhante, MS, there were selected three pasture areas, with and without termite nests, and it was evaluated according to indicators of pasture degradation: soil fertility, soil texture, microbial biomass, potentially mineralizable N, light fraction of soil organic matter (SOM), amount of existing litter and litter deposited in 28 days, and soil invertebrate macrofauna. The indicators tested showed no differences between the areas, only the parameters related to plant, regrowth and litter, showed a numerical trend in the different areas. In Chapter III, conducted in Anauril?ndia (MS), soil texture, soil fertility and amount of existing litter were evaluated in 16 areas. There was no relationship between the number of nests and soil chemical attributes. There was a negative relationship between the number of nests in relation to the content of SOM and cation exchange capacity (CEC), with a trend of least amount of nests with highest SOM and CEC observed in these areas. There was no trend toward increased number of nests in areas with less litter. The largest number of epigean termite nests builders was not related to the degradation parameters evaluated; the highest density was not always related to the pasture age, but the distribution form appears to be conditioned by ecological factors.