Stubble manipulation in a herbaceous comunity of a thinned caatinga in central sertão of Ceará

Abstract

The objective of this research was to evaluate the effects of the increasing percentages of fitomass removal on the phytosociologic and production parameters of the herbaceous Inter of a thinned caatinga on a solodic planosol. The treatments, that were applied at the end of the rainy season, consisted of percentages of herbaceous layer phytomass removal, that means, 100, 75, 50, 25, 0 and check (cutting). (Ground cover was not affected by the treatments, but varied along the experimental period (P< 0,01). The frequency of Aristida setifolia H.B.K. did not change with the years, neither under the treatment effect, while those of Diodia sp. and Jaquemontia ferruginea Choisy increased from 1977 to 1980 but did not change by the removal percentage treatments. The frequency of Stylosanthes humilis H.B.K. increased and that of Hyptis suaveolens decreased with the increasing of mulch phytomass removal. The total phytomass availability decreased along the experimental period and showed significant differences (P<0,01) among the treatments. The removal percentages, the year and the interaction removal x year affected (P<0,01) the mulch accumulation