Desertification is a phenomenon that takes place in the arid, semiarid and dry subhumid areas of the Planet. Although its causes and consequences are well known, data and robust information are often insufficient to provide indicators that allow desertification effects to be measured precisely and efficiently. Accordingly, the objective of this study was to introduce a methodology for the drafting of a monitoring index for desertification, with indicators of vegetal coverage, taking the semiarid area of Paraiba State, Brazil, as the test example. For this purpose, we analyzed conserved and desertified areas (22 pairs), in which we evaluated the following parameters: woody species richness, woody plant density, canopy height, mean basal circumference, mean circumference at breast height and total absolute dominance. First, we selected the indicators, calculated the areas of coverage and measured the reference values. Subsequently, we obtained masses for the indicators, and developed and tested the desertification degree index (DDI). The DDI showed 99% accuracy and 95% efficiency, respectively, and was able to select indicators and evaluate the level of desertification in the test areas. The methodology is simple, inexpensive and replicable in other regions of the world as a means of monitoring and planning strategies to counter desertification.

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RESUMOO marmeleiro (Croton sp.) é planta que compõe a florística da vegetação de caatinga denunciando áreas antropizadas, promovendo assim a instalação de um espaço ideal para que outras espécies mais Palavras-chave: Marmeleiro, Caatinga, Manejo, Produção florestal. ABSTRACTThe quince is Croton sp. plant that makes up the flora of caatinga vegetation denouncing disturbed areas, thus promoting the installation of an ideal space for other species more sensitive and demanding to be located. Through a performance of Action Research was intended to verify from which the spontaneous quince the same potential to produce forest products and byproducts and how plants respond to some management initiatives, the Action Research was developed in Benedict's Farm Amorim, District Galante, municipality of Campina Grande, state of Paraiba -Brazil. Five plots of 20 m x 20 m sampling (. In plots 1 and 2, were sampled plants with diameter less than 3.0 cm in height and 0.30 m considered commercial plants. The commercials were considered not only numbered and labeled. The data obtained allow inferring that the total number of plants per hectare varies from 10,400 copies to 14,450 copies, quince plants make up 98.07% to 99.30% of the total plant. The quince made with commercial samples ranging from 8.33% to 11.49% (850 to 1650 plants / ha) for plots sampled the highest values were related to wood quality (58.82% to 72.72 %), followed by the production of rods (27.27% to 41.18%) where 8.33% (850 plants) 11.49% (1,650 plants) could be categorized as commercial, 58.82% to these 72.72% will be used to produce firewood and 27.27% to 41.18% will be used to produce rods. As the height of plants in these spontaneous quince ranged from 1.80 m a 4.00 m. There that most of the plants that produced rods had diameters of 3.32 cm to 3.47 cm commercial heights 1.98 m 2.10 m respectively. The cylindrical volume of 0.0020 m3 average booed at 0.0021 m3/plant for firewood and 0.0017 to 0.0020 m³ / plant to sticks. The management of quince, (cut) showed values from 10.88 to 14.04 sprouts with the average total of 12.67 shoots per plant. At the shallow cut in one portion, the herbaceous material in sheet form originated was the equivalent of 595.0 kilograms of green leaves / ha, to scrawl the values can vary from 8,400 kg / ha to 12,980 kg / ha showing strength biomass production of quince even under the most adverse.

This study aimed to evaluate the gas exchanges in genotypes of Nopalea cochenillifera Salm-Dyck in different seasons and times of the day. The experiment was conducted with the varieties Miúda and Baiana at the Experimental Station Prof. Ignacio Salcedo, belonging to the National Semi-Arid Institute (INSA), in the municipality of Campina Grande, State of Paraíba, Brazil. The treatments were distributed in a 24 × 2 factorial arrangement, corresponding to gas exchange evaluations performed every hour for 24 hours in the rainy season (June) and in the drought season (December). Analyzed were stomatal conductance, transpiration rate, CO2 uptake, and internal CO2 concentration, besides instantaneous water-use efficiency, intrinsic water-use efficiency, and instantaneous carboxylation efficiency. In both drought and rainy seasons, variety Baiana presented higher gas exchange intensity than the variety Miúda. In the rainy season, gas exchanges are potentialized in both varieties evaluated. In this period, the peak of CO2 uptake occurs from 1:00 a.m. to 3:00 a.m. for the verity Baiana, and from11:00 p.m. to 2:00 a.m. for the variety Miúda, whereas, in the drought season, it occurs from 11:00 p.m. to 2:00 a.m. for both varieties, with these constituting the ideal intervals for measuring gas exchanges in the field.

Forage cactus (Opuntia spp. and Nopalea spp.) is a crop tolerant to drought, high temperatures, and less fertile soils, which favors its cultivation in arid and semiarid regions and production of cladodes to animal feed. Intercropping may improve water use efficiency and increase agricultural production sustainability. The aim of this research was to evaluate the growth and yield of forage cactus genotypes intercropped with timber species under semi-arid conditions. Three forage cactus genotypes, erect prickly pear 'Orelha de Elefante Mexicana' [O. stricta (Haw.) Haw.], 'Miúda' [N. cochenillifera (L.) Salm-Dyck: syn. O. cochenillifera (L.) Mill.], and 'Baiana' [N. cochenillifera (L.) Salm-Dyck] in three cropping systems (monocropping; intercropped with Prosopis juliflora (Sw.) DC.; and intercropped with Mimosa caesalpiniifolia Benth.) were studied. All species were irrigated with treated domestic effluent water. Plants were evaluated after 2 yr of cultivation. The forage cactus intercropped with timber species had lower cladode weight, dry matter yield, and lower carrying capacity than forage cactus in monocropped system regardless of genotype. These results suggest that timber species may inhibit the yield of forage cactus, and intercropping is not recommended. In addition, there was no significant difference in the performance of forage cactus when intercropping with M. caesalpiniifolia and P. juliflora. The P. juliflora had greater growth performance when compared with M. caesalpiniifolia intercropped with Miúda and Orelha de Elefante Mexicana. However, when intercropped with the Baiana, the growth of P. juliflora and M. caesalpiniifolia are similar to each other.