Efeito do manejo da jurema preta ( Mimosa tenuiflora (WILLD.) POIR.) na vegetação herbácea em caatinga raleada e o enriquecimento com capim andropogon (Andropogon gayanus KUNTH).

Abstract

The Caatinga vegetation is composed by seasonal herbaceous and shrub strata, strongly influenced by rainfall distribution and marked presence of cacti. The objective of this study was to evaluate the effect of thinning and management of jurema preta (Mimosa tenuiflora (Willd.) Poir.) On the frequency, coefficient of similarity and availability of herbaceous vegetation. Federal of Campina Grande, PB. For this, 4 areas of 1 ha were used, subjected to 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 black jurema (Mimosa tenuiflora (Willd.) Poiret) in December 2015 and enrichment with andropogon grass (Andropogon gayanus Kunth.). Each area was subdivided into 4 smaller areas (45 x 45 m) for treatment application. Four treatments were applied: lowered and managed plants to allow the growth of one (01) regrowth; plants lowered and managed to allow the growth of two (02) sprouts; plants lowered and managed to allow the growth of three (03) sprouts; plants lowered and managed to allow the growth of all regrowths, ie after the lowering will not be subjected to any control. It was carried out in a randomized block design (DBC). To determine all variables, an iron frame (sample unit) with dimensions of 1.00 x 0.25 m 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 time of evaluation, highlighting species such as Mesosphaerum suaveolens (L.), Sida cordifolia L., Axonopus purpusii (Mez) Chase with high frequency values. There was no significant difference in the similarity coefficient, but presented values above 72%, indicating the great similarity of vegetation between the areas. For ground cover, there was no significant difference when compared Season 1 (E1) with Season 4 (E4). Even so, the highest results were observed in absolute values in E4. In the second chapter, the Tukey test was applied at 5% probability collecting 20 samples per area. There was a significant difference (P <0.05) between all analyzed seasons for all components under analysis regarding phytomass availability (kg DM / ha) of herbaceous species, indicating the importance of the evaluation period in determining this variable. The evaluation seasons significantly affected the participation of Sida cordifolia L. unlike that of other dicotyledons (OD) and grasses (G), which were not influenced. In treatments, the availability of herbaceous components and their participation were influenced. The availability of litter DM was influenced by the time of evaluation (E1 and E4), but not by the interaction between times and treatments. The rainy season contributes to the increase of the frequency of all evaluated species, except for the panasco grass, resulting in a high similarity coefficient (always higher than 76%).