Formación de un humedal en la costa norte del Perú: estabilidad biofísica y diversidad biológica

Se describe, analiza y reporta por primera vez la formación de un humedal costero en el sur de Salaverry (La Libertad, Perú). Se realiza la comparación del número de especies con otros humedales ubicados en áreas costeras de la región, empleando para ello imágenes satelitales de acceso público e información biológica. Se obtuvo una serie de tiempo suficiente para plantear una hipótesis sobre su formación, calculando el NDVI (Índice de Vegetación de Diferencia Normalizada) y NDMI (Índice de Humedad de Diferencia Normalizada) para confirmar su estabilidad e influencia. El resultado del análisis sugiere que el humedal sur de Salaverry se formó hace quince años por dos aportes antrópicos: filtraciones de agua dulces desde terrenos agrícolas y agua de mar usada para el bombeo del material dragado en las inmediaciones del Puerto de Salaverry. Por sus características ecosistémicas, el humedal se encontraría en las primeras etapas de sucesión ecológica, y a pesar de origen espontáneo, estaría operando como una laguna costera salobre que atrae fauna oportunista, principalmente aves.

The formation of a coastal wetland located south of Salaverry (La Libertad - Peru) is first described, analyzed, and reported, and their biodiversity is compared with regional wetlands located at coastal areas, using publically access satellite imagery and biological information. An adequate time-series was obtained to hypothesize their formation, calculating the NDVI (Normalized difference vegetation index) and NDMI (Normalized Difference Moisture Index) to confirm the stability and influence. The analysis suggests that the wetland south of Salaverry was formed fifteen years ago by two human sources: freshwater infiltration from farmlands and seawater used to pump the dredged material in the vicinity of the Salaverry Port. Because of its ecosystemic features, the wetland would be at the first stages of the ecological succession, and despite its spontaneous origin, it will be functioning as a brackish coastal lagoon attracting opportunistic fauna, mainly birds.

Spatial and temporal evolution of family-farming land use in the Tapajós region of the Brazilian Amazon / Evolução espacial e temporal do uso da terra para agricultura familiar na região do Tapajós, Amazônia Brasileira

Pressures on the Brazilian Amazon forest have been accentuated by agricultural activities practiced by families encouraged to settle in this region in the 1970s by the colonization program of the government. The aims of this study were to analyze the temporal and spatial evolution of land cover and land use (LCLU) in the lower Tapajَs region, in the state of Parل. We contrast 11 watersheds that are generally representative of the colonization dynamics in the region. For this purpose, Landsat satellite images from three different years, 1986, 2001, and 2009, were analyzed with Geographic Information Systems. Individual images were subject to an unsupervised classification using the Maximum Likelihood Classification algorithm available on GRASS. The classes retained for the representation of LCLU in this study were: (1) slightly altered old-growth forest, (2) succession forest, (3) crop land and pasture, and (4) bare soil. The analysis and observation of general trends in eleven watersheds shows that LCLU is changing very rapidly. The average deforestation of old-growth forest in all the watersheds was estimated at more than 30% for the period of 1986 to 2009. The local-scale analysis of watersheds reveals the complexity of LCLU, notably in relation to large changes in the temporal and spatial evolution of watersheds. Proximity to the sprawling city of Itaituba is related to the highest rate of deforestation in two watersheds. The opening of roads such as the Transamazonian highway is associated to the second highest rate of deforestation in three watersheds.

As pressões sobre a Floresta Amazônica Brasileira têm sido acentuadas por atividades agrícolas de muitas famílias que foram estimuladas a se estabelecer nessa região durante o Programa de Colonização do Governo Federal, na década de 1970. Os objetivos deste presente estudo foram de analisar a evolução espacial e temporal em termos de mudanças de cobertura da terra e uso da terra (CTUT) na região do baixo Tapajós, no Estado do Pará. Contrastam-se 11 bacias que são geralmente representativas do processo de colonização regional por agricultores familiares, e para tanto imagens de satélite Landsat de três diferentes anos (1986, 2001, e 2009) foram analisadas utilizando-se um Sistema de Informação Geográfica. Imagens individuais não-supervisionadas foram classificadas usando-se GRASS, e o algoritmo de classificação de Probabilidade Máxima, para todos os comprimentos de onda do espectro visível e infravermelho (1 a 5 e 7). As classes retidas para a representação do CTUT nesse estudo foram: (1) floresta primária levemente alterada; (2) floresta de sucessão; (3) terra agricultável e pastagem; e (4) solo nu. A análise e observação de tendências gerais em 11 bacias mostram que o CTUT tem mudado rapidamente. O desmatamento médio de floresta primária em todas as bacias foi estimado em mais de 30% no período de 1986 a 2009. A análise em escala local de bacias revela a complexidade do CTUT, notavelmente em relação a grandes mudanças na evolução espacial e temporal das bacias. A proximidade com a cidade de Itaituba, que se encontra em plena expansão, está relacionada com a maior taxa de desmatamento em duas bacias hidrográficas, ao passo que a abertura de estradas, como a Rodovia Transamazônica, está associada à segunda maior taxa de desmatamento em três bacias hidrográficas.

Relationships between Land-Use Types and Plant Species Used by Traditional Ethno-Medical System.

Aims: The agricultural frontier advances progressively on forested regions in Central Argentina, changing the landscape structure by extremely reducing the extension of native forests. In rural communities that are related to the forests, it is possible that severe changes in the landscapes can have an impact on the knowledge and uses of medicinal plants. The aim of this paper was to evidence some general patterns between the ethnobotanical information recorded in the Chaco region and some characteristics of the landscape. Specifically, we hypothesized that the knowledge on medicinal plants and their type (native or exotic) are related to different types of land use (i.e. different proportions of native forests). Place and Duration of Study: The study was performed 15 rural localities within the Chaco phytogeographic regionin Córdoba, Argentina, conducted between 2004 and 2012. Methodology: A total of 279 interviews were conducted. Plant species were identified according to their status (native or exotic), and a standardized proportion of exotic species was calculated for each site. The different types of land use and their proportions were estimated in 15 rural localities using satellite images. A Principal Component Analysis and a bivariate Spearman correlation were performed to analyze the associations among land-use types, the proportion of native forests and the knowledge of medicinal plants. Results: In general, people had known many native and exotic medicinal plants. Nevertheless, in those localities where landscapes have experienced higher deforestation rates, exotic medicinal plants are more available than native ones (cultivated in gardens and orchards). The tradition of maintaining exotic species in gardens may contribute to maintain the ethno-medical systems in regions of severe forest fragmentation. Conclusion: The disappearance of the forest showed a positive association with losses in the knowledge and use of native medicinal plants.