Banco de sementes e disponibilidade de forragem em caatinga enriquecida, adubada e diferida no Sertão Paraibano.

Abstract

The vegetation of the semiarid region is the Caatinga, characterized by the predominance of a shrub and tree layer composed of plants of low carrying capacity resulting in low income of animals. This study aimed to determine the density, composition and diversity of the four areas of Caatinga seed bank in the sertâo of Paraiba subjected to grazing goats (1) and assess the availability of forage in thinned Caatinga and enriched with Urochloa mosambicensis subjected to different levels of grazing deferment and phosphate fertilizers (2). Experiment 1 was conducted in December 2013, where eighty soil samples and litter in the 0-5 cm depth were collected in four study areas (20 / area) using an iron frame with 30 cm x 50 cm x 3 cm, arranged randomly in all plots. The floristic material of the species has been identified and deposited in the form of dried specimens in the Herbarium of the CSTR. The richness and abundance of species in each area were evaluated using the Shannon-Wiener Diversity Index and the distribution of individuals among species in the areas by the Uniform Pielou index. In the first area, 442 individuals were found, in area two 320 seeds germinated, in area three we counted 434 seedlings and in area four there was a total of 453 individuals. The seed bank of grazing areas studied is composed of a large number of individuals from four herbs and shrubs and tree component is represented by only one kind, characterizing the degradation process in which the areas are probably due to the grazing continuous animal associated with the absence of trees. Experiment 2 was conducted at Fazenda Lameirão UFCGCSTR using 24 crossbred goats. And two were held in the nursery of CSTR / UFCG. Four treatments were carried out in deferred management system: treatment I - animals enter the picket 20 days after the onset of rain; treatment II - animals enter the picket 31 days after the onset of rain; Treatment III - animals enter the picket 53 days after the onset of rain, and Treatment IV - animals enter the picket 82 days after the onset of rain. We used a completely randomized block design with four treatments and six repetitions, for the performance and the availability of MS. The treatments were distributed in the plots and phosphorus levels in the subplots. There was no significant interaction between levels of phosphorus and deferral to the availability of dry matter dicotyledonous current grass and other grasses. There was a significant interaction for the floristic composition of dicots and current grass variables, showing the influence of phosphorus fertilization levels in the production of MS except for composition of other grasses. For deferral and MS there were no significant differences for availability and floristic composition of broadleaved and other grasses at each level of deferral, except for the current grass. In relation to animal performance there was a significant effect of grazing deferment final weight. The phosphorus fertilization did not increase the productivity of dry matter. There was an increase in floristic composition in dicotyledones and Urochloa mosambicensis. The deferral periods did not change animal performance.