The present study tested the ecological apparency hypothesis in a Brazilian rural community. It used the use value to test the information gained through three types of calculations (UV change , UV general , UV potential ). A vegetation inventory was performed in two areas near Capivara, Paraí-ba, Brazil, and 112 informants were interviewed. For the hypothesis test, the Spearman correlation coefficient was used to correlate the phytosociological (vegetation) and ethnobotanical data (use value). The study recorded 25 useful species in the first site and 20 in the second site. Positive correlations were found in the first site, between the UV g to basal area and dominance, and between the UV c and basal area, dominance, and importance value. In the second site, between the UV g and both basal area and dominance and between UV c and basal area, density, and dominance. Apparency explained the local importance of useful plants in construction, technology, and fuel, but was not explanative of medicine. Also, important responses were observed for the different use values.

BackgroundThis study aimed to investigate the local botanical knowledge of native food plants in three rural communities, located in the semiarid region of Paraíba State, Brazil, verifying possibilities of differences of knowledge among communities and between men and women.MethodsSemi-structured interviews about native plant knowledge and use were conducted with all householders in each community, totaling 117 informants. The species similarity among the communities of Pau D’Arco, Várzea Alegre, and Barroquinha was compared with Jaccard index, and the use value index (UVgeneral, UVcurrent, UVpotential) was used to determine the most important species. The Kruskal-Wallis test was used to compare the use values among communities and genders. The consensus factor among the informants was calculated according to the uses cited, and the Wilcoxon test was used to compare the use values between men and women.ResultsWe recorded 9 species belonging to 8 genera and 8 families in Várzea Alegre; 10 species, 9 genera, and 9 families in Barroquinha; and 7 species, 7 genera and 7 families in Pau D’Arco. Spondias tuberosa Arruda (Anacardiaceae) in Várzea Alegre, Spondias sp. (Anacardiaceae) in Barroquinha, and Ximenia americana L. (Olacaceae) in Pau D’Arco were the most prominent species. Preparation methods are slightly different in the three communities, and there is low similarity about species use among the communities. Regarding gender, the analysis of use value among the communities evidenced significant differences only for UVgeneral among women, specifically between Barroquinha and Pau D’Arco. For men and women within each community, there is a difference only for UVpotential in Barroquinha.ConclusionThis study showed that the residents of the three rural communities have limited knowledge of native food plants found in their communities, but they know where to find them, which parts they may use and how to consume them. The fact is that men know plants that are more distant from the residences and women know those that are next to them.

The ecological apparency hypothesis seeks to understand the dynamics of use that a particular species has through its availability in vegetation areas. According to this hypothesis, apparent plants are the most collected and used by humans. This hypothesis was tested in the rural community of Santa Rita, municipality of Congo, in Cariri microregion (Paraíba state, Northeast Brazil). We calculated the use value (UV) for each species. For the phytosociological inventory, we adopted the point-quadrant method, plotting 500 points distributed in the vegetation areas of the community, registering the perimeter measurements and height of 2000 plants. Interviews were conducted with householders, totaling 98 informants (41 men and 57 women), and 24 species, 21 genera, and 11 families were recorded. The cited species were grouped into 11 utility categories. The Spearman correlation coefficient was used to correlate phytosociological and ethnobotanical data. The use values of the species did not correlate with phytosociological parameters. Regarding the use categories, there were positive correlations for fuel (UV with dominance and basal area), construction (UV with all phytosociological parameters), fodder (UV with all parameters), and poison/abortion categories (UV with density and frequency). Ecological apparency significantly explained the local importance of useful plants in fuel, construction, and fodder categories, and less significantly for poison/abortion.

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One of the biggest challenges in the intercropping system of two crops is to obtain the optimal dose of green manure and the adequate population density of the crops. So, the objective of this work was to evaluate the performance of beet and arugula intercropping, influenced by green manuring with Merremia aegyptia and Calotropis procera and arugula population densities in two cultivation years, in semi-arid environment. The experimental design used was in randomized complete blocks, with the treatments arranged in a 4 x 4 factorial scheme, with 4 repetitions. The first factor of this scheme consisted of equitable amounts of M. aegyptia and C. procera biomass (20, 35, 50 and 65 t ha-1 on a dry basis) and the second factor, by arugula population densities (40, 60, 80 and 100% of the recommended density for single cropping, corresponding to 400, 600, 800 and 1,000 thousand arugula plants ha-1). The production and its components were evaluated on beet and arugula. In addition to these characteristics, the following agro-economic indicators were also determined for each treatment: system productivity index (SPI), land equivalent coefficient (LEC) and monetary equivalent ratio (MER). The greatest agro-economic advantages of the beet with arugula intercropping were achieved with a system productivity index (SPI) of 53.47 t ha-1, land equivalent coefficient (LEC) of 0.84 and a monetary equivalent ratio (MER) of 1.56, respectively, combining 65 t ha-1 of M. aegyptia and C. procera biomass with the arugula population density of 1,000 thousand plants ha-1. The maximum optimized commercial productivity of beetroots in the system intercropped with arugula was 23.20 t ha-1 using 65 t ha-1 of M. aegyptia and C. procera and in the arugula population density of 1,000 thousand plants ha-1, while the maximum arugula productivity intercropped with beet was 9.65 t ha-1, in the same combination of green manures amount and arugula population density.