This project is part of the Esecaflor experiment (LBA), which consists in estimating possible effects of "El níno" by inducing an artificial drought, reducing about 80% of the rainwater reaching the soil from one hectare of dryland forest in the Scientific Station Ferreira Penna-Melgaço/Pará. We intend to establish abundance patterns for families of the order Diptera present in the litterfall, in relation to the experimental and control areas of Esecaflor, evaluating the effect of water exclusion on this group. The individuals were collected with Pitfall Traps and kept in the laboratory in 70% alcohol for identification. From June 2001 to November 2003, nine collections were made, two before and seven after the establishment of the experiment. So far, the material from the first six collections has been identified to the family level. The data show that the diptera did not show a significant difference in abundance between the plots in the pre-exclusion period, and after the implementation of the experiment this difference became significant for the Phoridae in the wettest months, April 2002 (T test M.O') and March 2003 (T test Tp. 0.00")' showing a decrease in abundance in the plot with water exclusion. The family Cecidomyiidae showed better response to the drier environment, significant difference between plots could be observed in the month of November 2002 (Test T}'.0. 009')' Drosophilidae responded better to a wetter site (control plot), showing significant difference among plots (Test X2 P.O.03341) in all months. Sciaridae was more abundant in the drier period, but showed no significant difference between plots for both periods (Test Xl P pre-excheão.0.9')92 eP ", cl,", o.0.J4(87)' Responses to water exclusion are variable among Diptera families. Continued taxonomic identification, advancing to the species level, will allow for greater precision in analyses of the responses of organisms to the microclimatic changes produced by the experiment.
|
