Efeito do raleamento da caatinga e do manejo da jurema preta (Mimosa tenuiflora) [Willd.] Poir.) na similaridade e produção de fitomassa herbácea.

Abstract

The vegetation of the Caatinga is composed of seasonal herbaceous and shrub strata, strongly influenced by the distribution of rainfall and the marked presence of cacti. The objective of this work was to evaluate the effect of thinning and management of jurema preta (Mimosa tenuiflora (Willd.) Poir.) On frequency, coefficient of similarity and phytomass availability of herbaceous vegetation. The work was carried out at Fazenda Lameirão, Federal University of Campina Grande, PB. For that, four areas of 1 ha were used, undergoing the thinning of woody species such as catingueira (Poincianella bracteosa (Tul.) L.P. Queiroz); Poincianella pyramidalis (Tul.) L.P. Queiroz) and quince (Croton sonderianus Muell. Arg), lowering of jurema preta (Mimosa tenuiflora (Willd.) Poiret) in December 2015 and enrichment with andropogon grass (Andropogon gayanus Kunth.). Each area was subdivided into 4 smaller areas (45x45m) for treatments. There were 4 treatments applied: plants lowered and managed to allow the growth of one (01) regrowth; plants that are lowered and managed to allow the growth of two (02) regrowths; plants lowered and managed to allow the growth of three (03) regrowths; plants lowered and managed to allow the growth of all regrowths, that is, after the demotion will not be submitted to any control. A randomized complete block design (DBC) was used. For determination of all variables, an iron frame (sample unit) with dimensions of 1.00x0.25m was used. For the first chapter, the χ2 test was applied, collecting 100 samples per area. The frequency of herbaceous species was influenced by the evaluation period, with species such as Mesosphaerum suaveolens (L.), Sida cordifolia L, Axonopus purpusii (Mez) chase with high frequency values. There was no significant difference in the coefficient of similarity, but presented values higher than 72%, indicating the great similarity of the vegetation between the areas. For soil cover, there was no significant difference when comparing Season 1 (E1) with Season 4 (E4). Even so, higher values were observed in absolute values at E4. In the second chapter, the Tukey test was applied at a 5% probability by collecting 20 samples per area. There was a significant difference (P <0.005) between all the periods analyzed for all the components under analysis regarding the availability of phytomass (kg DM / ha) of the herbaceous species, indicating the importance of the evaluation period in determining this variable. The epochs of evaluation significantly affected the participation of Sida cordifolia L. differently from that occurring to other dicotyledons (OD) and grasses (G), which were not influenced. In the treatments, the availability of the herbaceous components and their participation were not influenced. The availability of leaf litter MS was influenced by the evaluation period (E1 and E4), but not by the interaction between seasons and treatments.