Determinação da taxa de decomposição das fezes do elefante em três habitats na Reserva Especial de Maputo

Abstract

This study was carried out in the Maputo Special Reserve from January to March 1999. Its objectives were to determine the rate of decomposition of the.faeces.dojBlefante in three habitats (forest, savanna and grassland), to estimate the percentage of moisture in faeces and soils. , identify the macrofauna that participate in the decomposition of faeces and interpret the differences in rates between the three habitats based on the factors studied during the study period. For the study of decomposition rates, 90 piles of fresh elephant droppings were selected from the savanna, of which 30 were distributed in each of the three habitats under study. The piles were placed in each habitat and monitored at intervals of 3 days, recording changes in their characteristics as they moved from one stage to another until they disappeared. 6 piles of faeces were selected for the moisture study. From these, 3 samples were taken through 30 ml probes in each of the habitats, which were then taken to the laboratory, where they were placed in the greenhouse for 5 h and then weighed to calculate the difference between the initial and final weight. For the study of soil moisture, 3 samples were taken, through 30 ml probes, in each habitat. These were taken to the laboratory to determine the moisture using the method used to determine the moisture of the faeces. No significant differences were observed between the rates of decomposition of elephant droppings between the three habitats. The average rates of decomposition of elephant droppings in the forest, savannah and prairie were respectively 0.0129, 0.0117 and 0.0159. The average faecal humidity was 53.07% in the forest, 40.01% in the savanna and 40.82% in the prairie. There were no significant differences in faecal moisture between the three habitats. A significant negative correlation was observed between faecal moisture and decay rates in the three habitats studied. The average soil moisture in the forest, savanna and prairie was respectively 14.41%, 5.39% and 7.01%. Significant differences in soil moisture were observed between the three habitats. A negative correlation was observed between soil moisture and decay rates in forest, savanna and grassland. The average environmental temperature was 23.9° C in the forest, 27.2° C in the savanna and 31.1° C in the prairie. There was a significant difference in environmental temperature between the three habitats. There was a non-significant positive correlation between decomposition rate and ambient temperatures in the savannah and prairie. In the forest, a non-significant negative correlation was observed between the temperature of the environment and the rate of decomposition.

The average soil temperature was 26.02°C in the forest, 30.46°C in the savanna, 32.49°C in the prairie. Significant differences in soil temperature were observed between the three habitats. The average rainfall in the forest was 10.87 mm, 9.73 mm in the savanna and 7.79 mm in the prairie. There were no significant differences in precipitation between the three habitats. The macrofauna found in the three habitats consisted of 739 individuals, of which 41.68% were found in the forest, 32.61% in the savanna and 25.71% in the prairie. There were significant differences between the number of individuals found by habitat and by method used. There was a significant negative correlation between number of individuals, weight of individuals by volume and decomposition rates. The effect of macrofauna on decomposition rates was most notable in fresh faeces. Temperature and precipitation were more determining factors in the decomposition of faeces in the prairie than in the forest and savannah.