RESULTS AND DISCUSSION Cláusulas Exemplificativas

RESULTS AND DISCUSSION. The analysis of the soil water data showed large variations in total soil water in the two-meter soil profile along the months for all vegetations. These fluctuations in soil moisture were not similar in all the soil depths studied. Much of the monthly variation in soil water content occurred only at the surface (0 cm depth) and down in the 50-cm depth. At the depth of 100-cm and below, the water content in the soil was more uniform throughout the period of study in the three different vegetations. The differences in soil water content among the species studied were greatest in the surface layer of soil. Considering the 24 months of the study period, and taking the average monthly values of soil moisture content for the total profile, and rainfall data, these average values were used to construct Figure 2, which shows the mean annual fluctuation of total soil water, in mm, for the tropical pine forests in comparison with that of the “cerrado” vegetation, together with the mean monthly precipitation, and with the average values of moisture retention in the soil at 1/3 and 15 atm of negative pressure. The figure shows that the soil under “cerrado” vegetation was, in general, always more humid than the soils under the tropical pine forests. Between the pine species, the soil was always more humid under the Pinus oocarpa forest. The Pinus caribaea var. hondurensis forest, therefore, was responsible for the highest depletion of soil water throughout the study period. The differences in soil water utilization among the covers tended to be higher during the dry months of the year. As shown in the average pattern of soil moisture utilization of Figure 2, only in the case of P. caribaea plot did the soil water content fall below the 15 atm tension during the driest period of the year (august-september). The differences in soil water regime thus discussed are, therefore, in terms of monthly values of soil moisture, species studied, and different depths of the soil profile. To test the significance and the extent of these differences, the data was submitted to analysis of variance. Table 3 summarizes the results of the separate analyses: Table 3: Analysis of variance for the monthly values of soil moisture contents in the three different study vegetation. Source d.f. S.S. M.S. F Species (S) Depths (D) Interaction (SxD) Error 2 4 8 276 301,46 37,80 189,16 1013,71 150,73 8,20 23,65 11,02 6,37* 0,35 n.s. 2,15* * significant at the 5% level