Few investigations have examined the structural controls of bark on its water storage and influence on stemflow, despite the bark being considered a critical component that determines the time and magnitude of this process. This study seeks to answer the question: Do bark water absorbability and wettability estimates correlate with stemflow yield? We hypothesized that (1) the absorbability and wettability are correlated, that is, greater water absorbability implies greater wettability, and (2) high rates of bark water absorbability and wettability has a strong and negative correlation with stemflow generation. Stemflow yield (Sy) was monitored over 12 months for 31 trees, representing 9 species common to the Brazilian savanna ecosystem known as Cerrado. Bark absorbability, per unit dry weight, changes over time of the water absorbability (BWA - by submersion methodology), bark drying (BWD), bark absorbability rate (BWArate), bark drying rate (BWDrate), and wettability (initial contact angle – CAin and CA rate - CArate) were determined under laboratory conditions. As insoluble lignin may also act to alter bark water storage dynamics, for each species, the bark insoluble lignin content was characterized. Stemflow variability was significant across the study species. Funneling ratios (FR) indicates that all species’ canopies diverted enough rainfall as stemflow to concentrate rainwaters at the surface around their stem bases (FR > 1). Differences in bark water absorbability were notable some of tree species. A decrease in the CA value as a function of time was not observed for all barks, which in association with stemflow yields, allowed a novel classification method of wettability, based on CAin and it’s rate of change: highly wettable (CAin ≤ 75.3° and CArate ≥ 0.26°h–1) and non-wettable (CAin ≥ 93.5° and CArate ≤ 0.13°h–1). So, only from the wettability classification could be observed that the non-wettable bark species presented higher Sy, FR, BWA, and BWArate than highly wettable bark species. The stemflow from species with highly wettable bark had a strong and positive correlation with BWA. On the other hand, non-wettable bark stemflow yield has a strongly and negative correlation with FR, CAin, and BWArate. Thus, bark wettability properties showed to deserves special attention. This novel classification of bark wettability had a substantial effect on stemflow yield comprehension and proved to be an important variable to link laboratory and field investigation for understanding the stemflow yield. These findings will improve our understanding of the stemflow dynamics, water balance and the ecohydrology processes of forest ecosystems.

The reaction wood is formed in an attempt to remain upright tree in response to the action of forces such as winds, irregular crown or slope of the land that tend to incline it. In hardwoods, as in Eucalyptus, this type of wood is called tension wood and occurs in the region of the stem facing the face of force application. Indicative of the presence of this type of wood is the high shrinkage and basic density compared to normal wood. Once the basic density and shrinkage are parameters for determining the quality of the wood, this study aimed to evaluate the variation of basic density and shrinkage of opposite and tension wood along the radius in four species of Eucalyptus sp. Four tree species Eucalyptus camaldulensis, Eucalyptus maculata, Eucalyptus pilularis and Eucalyptus urophylla, with 32 years of age, were taken from an experimental planting of the Federal University of Lavras. Specimens were made to represent the diametrical variation of the opposite of tension wood in disks cut at the dbh. The results indicate that the properties of radial, tangential and volumetric shrinkage, coefficient of anisotropy and basic density did not differ statistically between the tensionand opposite wood.

RIBEIRO, A. I.; DIAS, H. C. T.; BESSI, D.; TONELLO, K. C.; The dynamics of the substrate recovery of waste dumps in calcary mining under natural regeneration. CERNE, v. 24, n. 1, p. 18-26, 2018. HIGHLIGHTSEvaluate the dynamics of the physical and chemical recovery of the substrates of waste dumps of different ages undergoing natural regeneration, in a calcary mining.Characterization of the vegetation, vegetation and physical and chemical cover of the substrates of the abandoned waste dumps since 1994 and 2013 and the soil of a native forest fragment adjacent to the mining was carried out.The soil cover rate with herbaceous, grassy, regenerating and litter of the sterile stacks are similar to the native forest fragment.The same was observed for the physical characterization of soil resistance to penetration, soil moisture content and relative light index. ABSTRACTThis study aimed to evaluate the dynamics of the physical and chemical recovery of the substrates of waste dumps of different ages undergoing natural regeneration, in a calcary mining in Salto de Pirapora -SP, Brazil. Characterization of the vegetation, vegetation and physical and chemical cover of the substrates of the abandoned waste dumps since 1994 and 2013 and the soil of a native forest fragment adjacent to the mining was carried out. Twelve plots of 10x10m were allocated in each environment. It was verified that the soil cover rate with herbaceous, grassy, regenerating and litter of the sterile stacks are similar to the native forest fragment. The same was observed for the physical characterization of soil resistance to penetration, soil moisture content and relative light index. For the chemical characteristics, in all areas sampled there is aluminum deficiency which, consequently, presented low potential acidity and alkaline pH. The CEC of the substrates of the waste dumps presented values similar to the CEC of the native forest fragment, with abundance in some essential nutrients, indicating the possibility of vegetation development in the sterile stacks and the contribution of the natural regeneration to the substrates. Thus, the plant-soil relationship via natural regeneration in the sterile piles contributed to the improvement of the edaphic quality of the substrates over time, being a potential form of recovery in calcary mining. Thereby, the Fabaceae predominated on the waste dumps, especially Leucaena leucocephala, which, despite being an exotic species, is relevant for the current recovery stage of the substrates.

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O presente trabalho buscou avaliar os impactos do plano diretor de um município sob a perspectiva de produção e conservação de serviços ambientais. Localizada em Sorocaba (SP), a microbacia do Pirajibu-Mirim foi delimitada como área de estudo, e mapas de zoneamento, uso do solo, modelo digital de elevação e declividade foram elaborados. Com a análise dos dados, observa-se que a zona rural (ZR) e a zona de conservação ambiental (ZCA) sofreram reduções, assim como o tamanho mínimo estipulado para lotes em zonas de chácaras urbanas (ZCH). Embora atividades agrícolas sejam escassas no município, essas zonas são imprescindíveis para o aumento da permeabilidade do solo nas cidades e, quando manejadas corretamente, contribuem para a recarga dos lençóis freáticos. Além disso, grande parte da microbacia é ocupada por áreas degradadas e ociosas. Diante desse contexto, são sugeridas alternativas em curto e médio prazo para a melhoria da permeabilidade do solo em uma microbacia produtora de água. Palavras-chave: bacia hidrográfica; zoneamento; uso do solo; gestão de recursos naturais.