ABSTRACT: Increasingly, fast-growing forest plantations are able to support the wood supply but may simultaneously reduce water availability. The trade-off between wood production and water supply is more evident in areas with low water availability, high seasonal variation, or high water demand from local communities. The management regime adopted in forest plantations can either increase or reduce this trade-off. Thus, we assess herein the water and wood supply under different fast-growing forest plantation management regimes to understand how forest management practices can balance the provision of these services. The study was conducted at two catchments with a predominance of fast-growing forest plantations, namely, the mosaic management catchment (MMC) and the intensive management catchment (IMC). Rainfall and streamflow were monitored for three water years. Hydrological indexes were calculated to assess the hydrological regime of both catchments, and make inventories of the forest to assess forest growth rates. MMC had streamflow coefficients, baseflow index and baseflow stability higher than those of IMC. Mean annual wood increment was 32.73 m3 ha-1 yr-1 in MMC, with a mean age of 15 years, and 44.40 m3 ha-1 yr-1 in IMC at coppice in the second year. MMC hydrological indexes remained stable over the period studied, while in IMC the hydrological indexes were affected by climatic variations, mainly in drier years. MMC showed potential for supplying both water and wood. However, in IMC there was a trade-off between wood supply at the expense of the water supply. Thus, the intensity of fast-growing management can be adjusted to achieve a balance between water and wood supply on a catchment scale.

ABSTRACT Distributions of aquatic macrophyte species are commonly associated with water chemistry characteristics. However, other environmental factors that can lead to the occurrence of aquatic plants in lotic ecosystems, such as dynamic habitats linked to the surrounding landscape, have been underestimated. This study aims to evaluate landscape features that may influence the occurrence of species of euhydrophyte aquatic macrophytes in a tropical river basin. We assessed the occurrence of the following seven species: Egeria densa, Cabomba furcata, Potamogeton pusillus, Potamogeton polygonus, Utricularia foliosa, Pistia stratiotes and Salvinia molesta. We also measured environmental variables related to three spatial scales, local (limnological), channel and riparian landscape, along 25.5 Km of the Itanhaém River basin (São Paulo, Brazil). We found that local (limnological) and channel characteristics were important variables in determining the occurrence of aquatic macrophyte species while the landscape scale had little influence on species composition. Channel depth and margin slope were especially relevant abiotic variables in explaining the occurrence of four of the species but not P. pusillus, P. polygonus and U. foliosa. Our results highlight the importance of channel morphology for understanding aquatic plant occurrence and community composition in tropical rivers.

ABSTRACT: Awareness of evapotranspiration (ET) and crop coefficient (Kc) is necessary for irrigation management in coffee crops. ET and Kc spatial variabilities are disregarded in traditional methods. Methods based on radiometric measurements have potential to obtain these spatialized variables. The Kc curve and spatial variability of actual evapotranspiration (ETa) were determined using images from Landsat 8 satellite. We used images of young and adult coffee plantations from OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor) sensors over a two-year period. Evapotranspiration was estimated using the Surface Energy Balance Algorithm for Land (SEBAL). Moreover, the reference evapotranspiration (ETo) was estimated through the Penman-Monteith method. We obtained the values for the evapotranspiration fraction (ETf), analogous to Kc, according to ET and ETo values. The study was conducted in Buritis, Minas Gerais State, Brazil, in areas cropped with Coffea arabica irrigated by central pivots. A comparative analysis was made using different statistical indices. Average ETa was 2.17 mm d−1 for young coffee plantations, , and the Kc mean value was 0.6. For adult coffee plantations, average ETa was 3.95 mm d−1, , and the K mean value was 0.85. The ET and K data obtained based on the SEBAL algorithm displayed similar values to studies that used traditional methods. This model has huge potential to estimate ET of different stages of coffee plantation for the region studied.

Resumo Neste artigo, ao utilizar isótopos estáveis de carbono, nós avaliamos as influências presentes e pretéritas do uso da terra a que as áreas ripárias estão sujeitas quando situadas dentro de paisagens agrícolas. Ênfase é dada ao entendimento dos efeitos do Código Florestal de 2012 em tais áreas. Nós selecionamos cinco áreas ripárias em uma paisagem agrícola altamente dominada por plantas C4. Três delas apresentam faixa ripária de floresta nativa (FRFN) de 30 metros de largura e as outras duas apresentam FRFN de 8 e 0 m (i.e. sem FRFN). Nós utilizamos três transectos de 100 metros localizados a 5, 15 e 30 metros de distância do canal fluvial para obter amostras de solo (0 - 10 cm). Todas as áreas ripárias apresentaram assinaturas isotópicas do carbono do solo que não são C3 (floresta nativa) independentemente de apresentarem ou não FRFN de 30 metros. Os dois casos em que FRFN era menor que 30 m apresentaram maior contribuição de carbono oriundo de plantas C4. Todas as outras três áreas com FRFN de 30 m também apresentaram, em algum grau, carbono oriundo de plantas C4. Todas as outras três áreas com FRFN de 30 m também apresentaram, em algum grau, carbono oriundo de plantas C4 que foi atribuído è deposição de matéria orgânica de plantas C4 originada das áreas cultivadas e, em um caso, è persistência de gramíneas exóticas pré-existentes. Com o Código Florestal de 2012 permitindo FRFN mais estreitas (< 30 metros), nós esperamos que a contribuição de plantas C4 para a matéria orgânica permaneça alta em áreas ripárias e rios dentro de paisagens agrícolas dominadas por plantas C4 onde a FRFN de 30 m não é mais uma obrigação. Tais contribuições irão, provavelmente, continuar a ter efeitos prejudiciais è qualidade de água dos rios e à sua biota.

Abstract In this article, by using carbon stable isotopes, we assessed the past and present land use influences that riparian areas are subject within agricultural landscapes. Emphasis is given to the understanding of the effects of the 2012 Brazilian Forest Act on such areas. We selected five riparian areas within a highly C4 dominated agricultural landscape. Three of them had 30 meters native riparian forest buffer (NRFB) and two of them had 8 meter and no NRFB. We used three 100 meter-transects located 5, 15 and 30 meters relative to stream channel to obtain soil samples (0 - 10 cm). All riparian areas presented soil carbon isotopic signatures that are not C3 (native forests) irrespective of having or not 30 meters NRFB. Two cases presenting less than 30 meters NRFB had higher C4 derived carbon contribution. All of the other three areas that followed the 30 meters NRFB presented, to some degree, C4 derived carbon, which was attributed to C4 organic matter deposition originated from cultivated areas and, in one case, to the persistence of former exotic grasses. With the 2012 Forest Act allowing narrower buffers (< 30 meters), we expect C4 contributions to soil organic matter to remain high in riparian areas and streams within agricultural landscapes dominated by C4 plants where 30 meter NRFB is no longer required. Such contributions will likely continue to have detrimental effects on stream water quality and biota.

A existência de uma relação entre cobertura florestal e provisão de água é foco de estudos há décadas, especialmente no que diz respeito às funções eco-hidrológicas da vegetação situada em diferentes posições do relevo. Neste artigo, fazemos uma síntese da literatura sobre essas funções e analisamos como as mudanças recentes no Código Florestal Brasileiro podem afetar essas relações. Mostramos que a posição no relevo da vegetação nativa altera as funções eco-hidrológicas que elas exercem, sendo mais voltadas para a recarga de aquíferos, ou para a redução do escoamento superficial e contenção de processos erosivos, ou para a proteção de corpos d'água, ou ainda como elementos auxiliares em todas essas funções. Assim, é necessário haver cobertura vegetal em cada posição do relevo, para garantir a provisão das funções eco-hidrológicas no conjunto de uma bacia. O novo Código Florestal, ao promover uma redução da proteção da vegetação em todas as posições do relevo, deverá reduzir a capacidade de provisão de água em qualidade e regularidade compatíveis com as demandas futuras. Para reverter essa situação, é necessário estabelecer novas políticas públicas que promovam a manutenção ou a restauração da vegetação natural em todas as posições do relevo.

The relationship between forest cover and water supply has been studied for decades, especially in regard to the ecohydrological functions provided by native vegetation. In this study, we present a literature synthesis of the different ecohydrological functions provided by the forests and how the provision of these functions may be affected by recent changes in the Brazilian Forest Code. Depending on the location in the watershed, the functions provided by the forests can be more associated to aquifer recharge, to the reduction of runoff and erosion, to the protection of water bodies, or complementing all these functions. Thus, forest cover is needed in different regions of the watersheds to ensure the provision of all ecohydrological functions. The new Brazilian Forest Code reduced the legal protection of vegetation in all the different regions of the watersheds, and may reduce provision of water resources in adequate quality and regularity needed to supply future demands. To mitigate this situation, it is necessary to establish new public policies to maintain or restore native vegetation in different regions of the watersheds.

Na bacia do rio Corumbataí, a vegetação natural ocupa menos de 3% de sua área total, e a ausência dessa vegetação florestal tem levado ao aumento dos processos erosivos e ao desequilíbrio do regime hídrico de seus rios, causando diversos problemas no abastecimento de água de várias cidades, como Piracicaba e Rio Claro. Desse modo, existe a necessidade de um reflorestamento criterioso em áreas dessa bacia. No entanto, devido à limitação de recursos, é necessário que sejam realizados estudos de seleção de áreas prioritárias para que, com os recursos disponíveis, o ganho ambiental das áreas restauradas seja máximo. O objetivo deste trabalho foi desenvolver um método de priorização de áreas para restauração florestal baseado no uso de indicadores de sustentabilidade em microbacias. Cinco indicadores foram utilizados: porcentagem de mata nativa na APP; descontinuidade da vegetação nativa na bacia; diversidade da paisagem; variação média do uso da terra; e suscetibilidade à erosão. A seleção das microbacias para restauração das áreas de APP foi realizada por meio da ponderação linear dos indicadores e ordenamento das microbacias. Simulação inicial foi realizada para a seleção de 1.000 ha para restauração, e os resultados indicaram que os indicadores representam diferentes aspectos de sustentabilidade das microbacias. O método foi considerado útil na seleção de microbacias em condições extremas, diferenciando aquelas que necessitam de ações de conservação daquelas que necessitam de ações de restauração.

In the Corumbataí river basin, State of São Paulo, forest remnants occupy less than 3% of the original total area, and the absence of this natural vegetation has been increasing erosion and disturbing hydrological regime of its streams, causing many problems on water supply in urban areas like Piracicaba and Rio Claro. This situation shows the need of a well planned reforestation in areas of this watershed. However, since the funds are limited, it is necessary a site selection study to use available fund on reforestation projects considering the maximum environmental gain. This study aims to develop a site selection method for reforestation based on sustainable indicators of catchments. Five indicators were considered: native forest proportion in the Permanent Preservation Areas (APP); native forest discontinuity in the basin; mean variation of land-use; Shannon landscape diversity index; and mean erosion susceptibility. Catchment areas were selected using linear weighting of indicators and ranking of catchments. An initial simulation was made to select the best 1.000 ha for reforestation and the results showed that the indicators were able to capture distinct aspects of catchment sustainability. The method was considered useful for selecting catchments at extreme conditions, differentiating those that need conservation actions from those that need restoration actions.