Micro-topography associated to forest edges

Forest edges are often defined as the discontinuity between the forest habitat and an adjacent open habitat, thus they are based on a clear difference in the structure of the dominant vegetation. However, beside this very general definition, in the field we can observe a large diversity of edges, with often different kinds of micro-topography features: bank, ditch, stone wall, path, etc. As these elements are rather common in many temperate forest edges, it seems important to start to characterize them more clearly and with consistency. From a set of observations in south-western France, we build a first typology of the micro-topographic elements associated to forest edges. For each of them we describe the process, natural or human induced, at their origin, and according to the literature available, we identify some of their key ecological roles. Banks, generated by the differential erosion between forest and crops along slopes, are especially analyzed since they are the most common micro-topographic element in our region. It offers many micro-habitat conditions in the soil used by a wide range of species, notably by several bee species. More research is required to study in details the importance of such micro-topographic elements

The Effectiveness of Protected Areas in Central Africa: A Remotely Sensed Measure of Deforestation and Access

For protected areas that are extensively forested, the rate of deforestation is one indicator of the integrity of the protected area, and the effectiveness of protected area management. The goal of this study was to examine the deforestation rate in protected areas in Central Africa. Using remote sensing techniques, I measured levels of deforestation in 87 protected areas in five countries in Central Africa from 1990-2000. To examine possible causes of deforestation I also measured the level of access in these protected areas. A lack of access to remote areas can limit deforestation, forest degradation, and the resulting loss of biodiversity while decreasing development in rural areas. Access was defined either as natural (rivers) or constructed (e.g. roads or transmission lines). The annual net deforestation rate for protected areas in Central Africa, among the protected areas studied, was 0.05%. This is lower than the annual rate of forest loss found by other studies for the entire Congo Basin forest. Based on the rates of deforestation in the entire Congo Basin and the assumption that protected areas are trying to avoid deforestation, this suggests that Central African protected areas may be effective safeguards against deforestation. Five of the 87 protected areas exhibited zero deforestation, while one forest reserve, Kaga Bandoro in the Central African Republic, showed a five percent net increase in forest cover since 1990. Cameroon's protected areas had significantly higher levels of deforestation than those in the other countries in Central Africa. Within protected areas in each country studied there was a similar level of reforestation of 5%. Deforestation in a 10km area around protected areas was not significantly higher than that found within the protected areas. Protected areas that border other protected areas had significantly lower levels of deforestation than protected areas that were isolated from each other. The increased disturbance caused by increasing access to the forest seems to be of an ephemeral nature, initially resulting in forest loss, but leading to reforestation. There was no difference in deforestation rates when a road or river bordered a protected area, or crossed through a protected area. Only the density of roads or rivers had an effect on the deforestation rates. The secondary impacts of human use on both the forest structure and the wildlife inhabiting the forest are likely to be detrimental, and worthy of further study

Modeling Culex tarsalis Coquillett abundance on the northern Colorado Front Range using a landscape-level approach

2012 Fall.Includes bibliographical references.Endemic and emerging vector-borne diseases are major health problems, and some of them are unlikely to be eliminated regardless of control efforts. The applications for remote sensing and Geographic Information System (GIS) data include the identification of larval mosquito habitats and forecasting of species distribution and abundance, thereby improving the ability to target control efforts to reduce the risk of transmission of vector-borne pathogens. The practicality for the incorporation of remotely sensed environmental data into a GIS has greatly enhanced the understanding for the spatial and temporal distribution patterns of vectors, thereby enabling improved vector control operations and disease management response. Since the initial detection of West Nile virus (WNV) in Colorado in 2002, the northern part of the Colorado Front Range has come to be recognized as a high-risk area for WNV infections in humans, with 7.5% of the national cases of WNV being reported from Boulder, Weld and Larimer counties during 2003-2011. Culex tarsalis Coquillett is recognized as the primary species of concern in the transmission of WNV to humans along the northern Colorado Front Range. Before implementing the tools needed to control the spread of a vector-borne disease, public health agencies and organization officials must consider the spatial and temporal factors which are driving the interactions between the pathogen, the vertebrate host(s), and the vector(s). A sound understanding of the vector biology will vastly improve the efficacy for its control. Previous research performed on the northern Colorado Front Range used National Land Cover Data (NLCD) and IKONOS satellite imagery to model adult mosquito abundance of Cx. tarsalis. I applied a landscape-level approach to elucidate the effects of landscape-level environmental factors (independent or predictor variables) at multiple spatial extents on monthly adult Cx. tarsalis abundance (dependent variable) in Fort Collins, Loveland and Johnstown, Colorado using GIS technology. Multiple regression models provided empirical evidence for the seasonal variability in adult Cx. tarsalis populations. A more detailed representation for the importance of spatial extent for elevation, slope, distance to and area of irrigated lands and the distance to larval mosquito sites was obtained from this study. Multiple regression models developed using stepAIC were able to explain and forecast monthly adult mosquito abundance with accuracies ranging from 43%-73% in Fort Collins and 36%-68% in Loveland and Johnstown. The expression of environmental variables also differed by month and year. Mean elevation within a 500 m buffer of mosquito trap locations in Fort Collins were negatively correlated with mean monthly adult Cx. tarsalis abundance. A positive relationship existed between mean monthly adult Cx. tarsalis abundance in Fort Collins and the perimeter of larval mosquito habitats within a 1.0 km buffer of traps and the distance to irrigated lands at a spatial extent of 500 m around traps. Mean elevation, slope and distance to larval mosquito sites at a spatial extent of 500 m provided improved predictive power for mean monthly adult Cx. tarsalis abundance in Loveland and Johnstown. My results indicate that landscape and topographic heterogeneity within the study area are interacting on a monthly basis in different ways, resulting in varying populations of adult Cx. tarsalis mosquitoes. I believe it is a combination of interactions between landscape variables identified in this study and weather variables which determines the seasonal spikes in mosquito abundance. The ability to understand the factors that drive vector abundance is critical in managing risk and will aid large scale Integrated Pest Management efforts

La influencia de la privatización de bienes comunes en la sostenibilidad cultural y ecológica de las sabanas e islas del Caribe colombiano

Partiendo del paradigma de la sostenibilidad crítica y el estudio de los sistemas socioecológicos (SES), esta tesis busca comprender de qué manera las dinámicas de privatización de las tierras y los bienes comunes influyen en la sostenibilidad de los sistemas socioecológicos de la región insular y de sabanas del Caribe colombiano en cuatro subregiones habitadas por pueblos afrodescendientes que se han transformado en los últimos años. Teóricamente la tesis busca articular un marco analítico que integra transdisciplinariamente los estudios ecosistémicos con la perspectiva de la justicia socioambiental intercultural. Por un lado, el enfoque de los SES permite establecer unidades de análisis de gran complejidad organizacional, tanto espaciales como temporales, y posibilita descripciones densas de las interacciones y los actores en la complejidad ecológica, económica y sociocultural en la que ocurren. Por otro lado, la justicia socioambiental intercultural exige un análisis desde el pluralismo social y cultural considerando las contribuciones y responsabilidades específicas de los diversos actores frentes a los desafíos comunes de la sociedad, incluidos los desafíos ecológicos, a la vez que implica analizar la configuración histórica de un territorio, identificar el vínculo entre las estructuras ecológicas y políticas que subyacen a los conflictos y cambios relacionados con acceso y regulación de bienes comunes. Para dar cuenta de ello, los tres artículos científicos que constituyen el cuerpo principal de esta tesis han seguido un diseño metodológico similar. Basándose en fuentes cartográficas y sensores remotos (fotografías aéreas e imágenes satelitales), se hizo la descripción socioespacial de las coberturas y su cambio multitemporal para tener evidencias biofísicas de cómo se transforman los ecosistemas en regiones donde las nociones y figuras privadas irrumpen en la configuración colectiva del uso y tenencia de la tierra y los bienes comunes. Asimismo, en todos los casos se empleó un enfoque etnográfico para la descripción de los sistemas socioecológicos a partir del conocimiento ecológico local de las comunidades con las que se adelantó el trabajo de campo y se discutió críticamente las implicaciones ecológicas y culturales de los modelos privados en sus formas de vida. Por último, en los tres artículos se proponen categorías y variables para examinar la justicia socioambiental intercultural implícita, principalmente por el déficit de derechos que se pudo constatar, y la pertinencia que representa articular los criterios de justicia socioambiental en las dimensiones de la sostenibilidad. En los tres artículos se muestra que los efectos del cambio climático en los ecosistemas tropicales no pueden interpretarse basándose únicamente en variables físicas. La grave escasez de agua y el deterioro de los ecosistemas son más agudos en lugares donde se dan discrepancias históricas, como el acceso desigual a la tierra o a otros bienes y derechos necesarios para la subsistencia de los pueblos que las habitan. Las transformaciones ecosistémicas y sus repercusiones en los recursos hídricos tienen mayor severidad en regiones donde hay conflictos de uso, falta de claridad en los derechos de tenencia y dificultades de gestión y gobernanza. Es por ello por lo que se ha examinado la política pública de sostenibilidad que orienta los planes de uso de los ecosistemas y que, en la mayoría de los casos, busca estar alineada con la Agenda 2030. Sin embargo, los modelos de planificación del uso de la tierra y los modelos referidos a las costas que hemos podido historizar, muestran que en las últimas cinco décadas se han favorecido las prácticas de apropiación individual y los modelos turístico, agroindustriales y urbanísticos frente a las formas colectivas de pesca, recolección, pastoreo y otros sistemas de pequeña escala

Celebrating 25 Years of World Wetlands Day

The purpose of this Special Issue is to celebrate 25 years of “World Wetlands Day”. There is no other ecosystem that has its very own Ramsar Convention or such a challenge impacting ecosystem sustainability. Papers for this Special Issue provide an overview of wetland status and function within different regions of the world. The papers in this Special Issue of Land consist of three review papers, ten research articles and one perspective paper. Edward Maltby’s review paper provides us with an overview of the paradigm shift of how we value and assess wetlands over time. Ballut-Dajud et al. provide us with a worldwide perspective on factors affecting wetland loss. Finally, Jan Vymazal provides us with a historical overview of the development of water quality treatment wetlands in Europe and North America. The research papers can be grouped into four groups: 1) use of remote sensing to analyze stability and dynamic factors affecting wetlands; 2) factors affecting the wetlands’ ability to store carbon; 3) assessment of wetlands effect on water quality; and 4) understanding historical use and value of wetlands, farmer’s attitudes about wetland management, and how we can value wetland ecosystem services. Finally, Bryzek et al. remind us that, as wetland researchers and managers, we should minimize damage to wetlands even through field monitoring work

The global tree carrying capacity (keynote)

editorial reviewe

The Changing Matrix: Reforestation and Connectivity in a Tropical Habitat Corridor

In the last two decades, export-oriented crops and timber and fruit plantations have joined small-scale cultivation and pasture as important causes of tropical deforestation. Widespread conversion of tropical forest to agriculture threatens to isolate protected areas, which has led to efforts to maintain functional connectivity in landscapes between protected areas. Relatively few "landscape conservation" efforts have been assessed for their effect on deforestation, but advances in remote sensing now permit detailed monitoring of tropical land uses over time, including mapping of tree crops and plantations. This dissertation evaluates the long-term impact of forest conservation and reforestation policies on tropical forests in a habitat corridor. The following chapters test the capability of remote sensing to monitor tropical conservation efforts and assess whether landscape conservation policies can maintain forest cover and connectivity in the face of rapid agricultural expansion. Costa Rica has one of the most comprehensive landscape conservation policies in the tropics: a 1996 Forest Law banned deforestation and expanded payments for environmental services (PES) to protect forests and plant trees, prioritizing designated habitat corridors between protected areas. The long-term effect of the program on land-use transitions is not well known. To take advantage of this regional policy experiment, I used a time-series of five moderate-resolution Landsat images to track land-use change from 1986 to 2011in the oldest habitat corridor, the San Juan-La Selva Biological Corridor (SJLSBC). Forest conservation policies were associated with a 40% decline in deforestation after 1996 despite a doubling in the area of cropland in the last decade. The proportion of cropland derived from mature forest dropped from 16.4% to 1.9% after 1996, while one fifth of pasture expansion continued to be derived from mature forest. These results suggest that forest conservation policies can successfully lower deforestation, and that they can be more effective with large export producers than small-scale cattle producers. Tree plantations are an important component of Costa Rican PES, but knowledge of their distribution and contribution to connectivity in the corridor region is poor. After reviewing the remote sensing literature, I employed a novel integration of hyperspectral images and a Landsat time-series to create the first regional map of tropical tree plantation species. Including multitemporal data significantly improved overall hyperspectral map accuracy to 91%; the six tree plantation species were classified with 83% mean producer's accuracy. Non-native species made up 89% of tree plantations, and they were cleared more rapidly than native tree plantations and secondary forests. I combined existing land cover maps, field behavioral experiments, and a graph connectivity model to estimate whether landscape conservation policies increased connectivity for understory insectivorous birds, a representative forest-dependent group. The field playback experiments indicated both native and exotic tree plantations with a dense shrubby understory were acceptable dispersal habitat for all species, and that birds traveled readily near secondary forest edges but rarely into forested pasture. Graph model parameters were informed by these results. For all of these bird species, functional connectivity declined by 14-21% with only a 4.9% decline in forest area over time, implying that conservation policies have not caused a net increase in functional connectivity in the SJLSBC region. Despite making up 2% of the region, tree plantations had little effect on regional connectivity because of their placement in the landscape; we demonstrate that spatially-targeted reforestation of 0.1% of the region could increase connectivity by 1.8%. Collectively, the results presented in these chapters underline the potential and limitations of landscape conservation policies and corridor plans in the tropics; combining regulations and PES can lower deforestation over the medium-term, but increased enforcement, improved monitoring with remote sensing, and targeted conservation effort is needed to combat illegal deforestation and restore functional connectivity. Given numerous new tropical corridor and PES programs and the qualified successes of landscape conservation policies in Costa Rica and other tropical countries, our approach to the analysis can be applied to monitor and evaluate connectivity across the tropics