Abstract Limited experiential contact to natural environment can affect the knowledge of the local flora and, consequently, the intentions to conserve it. Therefore, this study aims to analyze whether high school students from Teresina (PI-Brazil) can identify more species of native than exotic plants and the factors that can affect this ability. 333 students from state public schools were interviewed through semi-structured questionnaires and with printed images of 20 species of plants found in the region. The data were analyzed using univariate non-parametric statistics. The results show that living in the countryside positively influenced the identification of local flora, but there was no significant difference in the number of identified plants between students who attended botany classes and those who did not. Two native plants (cashew-96.7% and pitomba-91.9%) and three exotic plants (mango-90.7%, guava-94.9% and acerola-82.0%) stood out among the most identified plant species. It was also found that, for two species of native plants very important for the State of Piauí, the caneleiro (0.6%) and the carnauba (26.7%), the identification rates were scarce. Thus, it is necessary to use Environmental Education and the teaching of Botany to prioritize native plant species, valuing local ecology and ensuring their protection.

Resumo A lenha é um dos mais importantes produtos florestais da região Nordeste do Brasil, e cada vez mais é necessário que sua exploração seja feita de maneira sustentável. Nesse sentido, o manejo florestal tem sido uma proposta de significativa melhoria das características ambientais dessa atividade. Este trabalho teve como objetivo identificar e analisar a atividade de exploração florestal por meio de Planos de Manejo Florestal Sustentável (PMFS) no estado do Piauí. Foram analisados dados de localização e produção, no período de 2010-2015. O diagnóstico dos PMFS do Piauí foi realizado por meio de consulta ao banco de dados da coordenação de licenciamento da Secretaria Estadual de Meio Ambiente e Recursos Hídricos - SEMAR, no período de janeiro a março de 2016. Os 96 PMFS detentores de autorização representaram 117.510,60 hectares de área manejada, em propriedades cujas extensões variaram de 67,60 a 34.208,00 ha, com área manejada por propriedade entre 40,00 e 24.969,00 ha. Os talhões adotados para a exploração anual tiveram dimensões entre 7,50 e 1.945,70 ha. O volume anual autorizado, no período, foi de 1.998.986,20 st/ano. A análise dos planos indica que o estado do Piauí possui capacidade de abastecimento de matriz energética proveniente de material lenhoso oriundo do manejo florestal, e que esta atividade, ainda, resulta em significativo benefício ambiental, pelo potencial de sustentabilidade que apresenta.

Abstract Wood is one of the most important forest products in the northeast of Brazil, and it is increasingly necessary that its exploitation can be carried out in a sustainable way. In this sense, the forest management has been proposing significant improvement of the environmental characteristics of this activity. The objective of this paper was to identify and analyze the activity of forest exploitation through Sustainable Forest Management Plans (PMFS), in the state of Piauí. The localization and the production data analyzed were in the period from 2010 to 2015.The diagnosis of PMFS in Piauí state was carried out by consulting the database of the licensing coordination of the State Department of Environment and Water Resources (SEMAR), from January to March 2016. The 96 PMFS holders of authorization accounted for more than 117.510,60 hectares of managed area, in properties in which extensions ranged from 67.60 to 34,208.00 ha, with an area managed by property between 40.00 and 24,969.00 ha. The plots adopted for the annual exploration had dimensions between 7.50 and 1,945.70 ha. The authorized annual volume in the period was 1,998.986.20 st/year. The analysis of the plans indicates that the state of Piauí has capacity to supply energy matrix from woody material of forest management activities and that this still results in a significant environmental benefit, due to the sustainability potential of the activity.

ResumenEn los bosques tropicales secos, la dinámica de las poblaciones herbáceas están fuertemente influenciadas por la variación estacional y anual de la precipitación total. Por otra parte, los acontecimientos presentes y pasados de anomalía climática (por ejemplo, años de sequía y lluvia errática antes de la temporada de crecimiento) pueden causar reducciones drásticas de tamaño de la población, lo que lleva a la desaparición temporal de algunas especies. Por lo tanto, este estudio tiene como objetivo evaluar, durante tres años, la dinámica de Delilia biflora (Asteraceae), Commelina obliqua (Commelinaceae), Phaseolus peduncularis (Fabaceae) y Euphorbia heterophylla (Euphorbiaceae). El estudio se realizó en una zona de bosque seco tropical conocida como Caatinga, situado en la estación experimental del Instituto Agronómico de Pernambuco (IPA), en Caruaru, Pernambuco, Brasil. La Caatinga tiene un clima semiárido y fuerte variación estacional y anual de la precipitación total. Durante este estudio, hubo un evento de anomalía climática llamado la sequía de 2006 y la lluvia errática en la estación seca. El nacimiento, la muerte y la supervivencia fueron monitoreados mensualmente en 105 parcelas de 1 × 1 m. Las diferencias en densidad entre años y estaciones se evaluaron mediante la prueba de Kruskal-Wallis. El poder explicativo de la precipitación del presente y del pasado sobre la densidad se evaluó utilizando el Modelo Lineal Generalizado. En este estudio, fue el primer registro de Euphorbia heterophylla en el área de estudio. Las poblaciones estudiadas fueron mayores en los años más húmedos y durante la temporada de lluvias, y se redujeron drásticamente en el año más seco y en las estaciones secas. Commelina obliqua fue la menos sensible a la variación de la precipitación total. Con respecto a la densidad, las cuatro especies estuvieron presentes durante los tres años. Las tasas de natalidad fueron mayores durante la temporada de lluvias y las tasas de mortalidad fueron mayores en la estación seca. Lluvias esporádicas en la estación seca causado pronunciado reclutamiento de plántulas seguida de muerte y tuvo un fuerte impacto en la dinámica de D. biflora, E. heterophylla y P. peduncularis. La precipitación del año en curso explica entre el 3 % y 18 % de la variación interanual de la densidad y el poder explicativo de la precipitación del año anterior en la densidad de las poblaciones varió de 32 % a 67 %. Por lo tanto, los fenómenos climáticos del pasado también tienen una consecuencia significativa para las cuatro poblaciones. En conclusión, la drástica reducción de la precipitación total entre años podría ser un parámetro predictivo para el tamaño de la población de plantas herbáceas (en el momento presente y futuro) en una área de bosque tropical seco en el Noreste brasileño.

AbstractIn tropical dry forests, the dynamics of herbaceous populations is strongly influenced by seasonal and annual variation in total rainfall. Moreover, the present and past events of climatic anomalies (e.g. severe drought years and erratic rain before the growth season) may cause drastic reductions in population size, leading to the temporal disappearance of some species. Therefore, this three-year study aimed to assess the dynamics of Delilia biflora (Asteraceae), Commelina obliqua (Commelinaceae), Phaseolus peduncularis (Fabaceae) and Euphorbia heterophylla (Euphorbiaceae). The study was conducted in an area of tropical dry forest known as Caatinga, situated in the experimental station of the Pernambuco Agronomic Institute (IPA), in Caruaru, Pernambuco, Brazil. The Caatinga has a semiarid climate with strong seasonal and annual variation in total precipitation. During this study, there was a climatic anomaly event called the 2006 drought, and also erratic rains in the dry season. The birth, death and survival of plants were evaluated monthly using 105 plots (1 × 1 m). Differences in density between years and seasons were evaluated using the Kruskal-Wallis test. The explanatory power of present and past precipitation on density was evaluated using the General Linear Model. In this study, we present the first record of Euphorbiaheterophylla in the studied area. The studied populations were larger during the rainy seasons and in wet years, and were drastically reduced in the driest year and dry seasons. Commelina obliqua was the least sensitive to variation in total rainfall. Regarding the variation in density, all four species were present during all three years. Birth rates were higher during the rainy season, and death rates were higher in the dry season. Sporadic rain in the dry season caused pronounced seedling recruitment followed by death, and had a strong impact on the dynamics of D. biflora, E. heterophylla and P. peduncularis. The precipitation of the current year explained between 3 % - 18 % of the inter-annual density variation, and the explanatory power of the previous year precipitation on the density of populations ranged from 32 % to 67 %. Therefore, climatic events of the past also have a significant consequence over the four populations. In conclusion, drastic reduction in total precipitation between years may be considered as a predictive parameter for herbaceous plants population size (in the present and future time) in a Northeastern Brazilian tropical dry forest area. Rev. Biol. Trop. 63 (4): 903-914. Epub 2015 December 01.