Percepções e ações em desertificação no município de São João do Cariri. Semiárido paraibano.

Abstract

Over the period between 2010 and 2013 three experiments were conducted in some properties in the municipality of São João do Cariri comprising Microregion of CaririParaibano, Mesoregion of Borborema, Sub-Basin of Taperoá River, Rio Paraíba Basin, Bioma Caatinga, Escorregão do Planalto, a Brazilian semi-arid region (experiment 1), The experiments in these areas considered to be Less Anthropized (experiment 1) Extremely Antropized (experiment 2), and Averagely Anthropized (experiment 3) revealed the existence of native vegetation (Witness Areas) identified as Pereiro(Aspidospermapyrifolium), Palmatória-de-Pelo (Tacingasp), Facheiro (Pilosocereussp), Jurema-Preta (Mimosa Tenuiflora), Catingueira (Caesalpiniapyramidalis), Juazeiro (Ziziphusjoazeiro), Marmeleiro (Croton sp), Xique-xique (Pilosocereussp), Qixabeira (Sideroxylonobtusifolium) and Pinhão(latrophasp). To recover the most degraded areas, the study team planted native species known as Macambira (Bromelialaciniosa) and xique-xique (Pilosocereussp), besides exotic species identified as Sisal Agave (sisalana)Aveloz (Euphorbia tirrucali), Buffel Grass (Cenchrusciliares) and Palma (Opuntia tuna), being the areas planted named Disturbed. Of all the native species planted, Sisal/Agave stood out in terms of survival with variations of 80,0% to 90,0%, being the average value of survival of the species planted 32,20%. The study collected physic and chemical samples of soil in both internal (named Witness and Disturbed) and external areas under experiment. Concerning the physical characteristics, the study discovered that there was a the highest level of loamy/sandy texture in both internal and external areas regardless of their history in terms of anthropization. Experiment 1 presented higher values of Electric Conductivity Clay and Available Water. Experiment 2 presented higher values of sand, hydrogen, nitrogen, potassium, phosphorus, sodium, organic carbon, organic matter, soil density and soil porosity. And experiment 3 revealed high values of Silte, Calcium, Magnesium, Sulfur and Ph. The density value of the particles was the same in all the experiments (2,67% g/cm3), being all the soils considered to be NON-SALINE. No aluminium contents has been found in any of the experiments. One of the best indicators do recover areas is the contents of organic matter - normally found in all the experiments and in the most different situations with very low values, pointing the need to intervene more specifically in the addition or creation (type of green fertilization) to most contents that could be shown higher in the area used for experiment 1 which was considered to be the oldest of all and less anthropized.