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Forest Managers (forest + managers)
Selected AbstractsHillslope-swamp interactions and flow pathways in a hypermaritime rainforest, British ColumbiaHYDROLOGICAL PROCESSES, Issue 15 2003D. F. Fitzgerald Abstract The process of water delivery to a headwater stream in a hypermaritime rainforest was examined using a variety of physical techniques and tracing with dissolved organic carbon (DOC) and the stable isotopes of water. Headwater swamps, often the major discharge zones for water draining off steep forest slopes, strongly affect the physical and chemical character of streamflow in the region. The headwater swamp selected for detailed investigation was sustained by relatively constant groundwater input from the steep colluvial slopes that maintained the water table above the ground surface. During significant storm events the water table rose quickly and the swamp expanded to engulf marginal pools that developed rapidly on the adjacent ground surfaces. The corresponding release of surface water directly to the stream typically comprised up to 95% of total stream discharge. The proportion of groundwater seepage to the stream by matrix flow (<1%) and via macropore-fed springs (up to 73%) increased during the recession period, but could not be sustained over the longer term. In more protracted drying periods, deep groundwater contributions to the stream were routed first to the headwater swamp. Dissolved organic carbon (DOC) in the stream, measured daily or more frequently during storm events, was found to be directly proportional to discharge, owing to the domination of DOC-rich headwater-swamp water sources. Although ,18O and ,2H composition of rainwater, groundwater and stream flow were found to be similar, deuterium excess (d ,2H , 8,18O) of water components was often found to be distinct, and suggested short water residence times of roughly 12 days for one event. Overall, observations of a typical headwater swamp reveal that the groundwater regime is dominated by rapid infiltration and short, emergent flow paths. With a relatively short turnover time, potential disturbances to the system by harvesting of upslope areas can be expected to occur rapidly. Forest managers can mitigate some of the harmful effects of logging operations by respecting the integrity of headwater wetland systems. The nature and magnitude of such perturbations will require further study. Copyright © 2003 John Wiley & Sons, Ltd. [source] Beyond Reaping the First Harvest: Management Objectives for Timber Production in the Brazilian AmazonCONSERVATION BIOLOGY, Issue 4 2007DANIEL J. ZARIN manejo de bosques; producción sostenida; sustentabilidad; tala de impacto reducido Abstract:,Millions of hectares of future timber concessions are slated to be implemented within large public forests under the forest law passed in 2006 by the Brazilian Congress. Additional millions of hectares of large, privately owned forests and smaller areas of community forests are certified as well managed by the Forest Stewardship Council, based on certification standards that will be reviewed in 2007. Forest size and ownership are two key factors that influence management objectives and the capacity of forest managers to achieve them. Current best ecological practices for timber production from Brazil's native Amazon forests are limited to reduced-impact logging (RIL) systems that minimize the environmental impacts of harvest operations and that obey legal restrictions regarding minimum diameters, rare species, retention of seed trees, maximum logging intensity, preservation of riparian buffers, fire protection, and wildlife conservation. Compared with conventional, predatory harvesting that constitutes >90% of the region's timber production, RIL dramatically reduces logging damage and helps maintain forest cover and the presence of rare tree species, but current RIL guidelines do not assure that the volume of timber removed can be sustained in future harvests. We believe it is counterproductive to expect smallholders to subscribe to additional harvest limitations beyond RIL, that larger private forested landholdings managed for timber production should be sustainable with respect to the total volume of timber harvested per unit area per cutting cycle, and that large public forests should sustain volume production of individual harvested species. These additional requirements would improve the ecological sustainability of forest management and help create a stable forest-based sector of the region's economy, but would involve costs associated with lengthened cutting cycles, reduced harvest intensities, and/or postharvest silviculture to promote adequate growth and regeneration. Resumen:,Bajo la nueva ley forestal aprobada en 2006 por el Congreso Brasileño, millones de hectáreas de bosques públicos están destinadas a constituir futuras concesiones madereras. Millones de hectáreas adicionales de extensos bosques privados y áreas reducidas de bosques comunitarios están certificadas por el Forest Stewardship Council por su buen manejo, con base en estándares de certificación que serán revisados en 2007. La extensión y tenencia del bosque son dos factores clave que influyen en los objetivos de manejo y en la capacidad de los manejadores para alcanzarlos. Las mejores prácticas ecológicas actuales para la producción de madera en los bosques de la Amazonía Brasileña están limitadas a sistemas de tala de impacto reducido (TIR) que minimizan los impactos ambientales de las operaciones de cosecha y que obedecen restricciones legales en relación con los diámetros mínimos, las especies raras, la retención de árboles semilla, la máxima intensidad de tala, la preservación de amortiguamientos ribereños, la protección del fuego y la conservación de vida silvestre. En comparación con la cosecha convencional, depredadora, mediante la cual se obtiene >90% de la producción de madera en la región, la TIR dramáticamente reduce el daño y ayuda a mantener la cobertura del bosque y la presencia de especies de árboles raras, pero los actuales lineamientos de TIR no aseguran que el volumen de madera removida pueda ser sostenido en futuras cosechas. Consideramos que es contraproducente esperar que los pequeños propietarios suscriban límites a la cosecha más allá de la TIR; que los bosques privados manejados para la producción de madera debieran ser sustentables respecto al volumen total de madera cosechada por unidad de área por ciclo de corte; y que los bosques públicos deberían sustentar el volumen de producción de especies individuales. Estos requerimientos adicionales mejorarían la sustentabilidad ecológica del manejo de bosques y ayudaría a crear un sector forestal estable en la economía regional, pero implicarían costos asociados con la prolongación de los ciclos de corte, la reducción de las intensidades de cosecha y/o la silvicultura postcosecha para promover el crecimiento adecuado y la regeneración. [source] Regeneration patterns and persistence of the fog-dependent Fray Jorge forest in semiarid Chile during the past two centuriesGLOBAL CHANGE BIOLOGY, Issue 1 2008ALVARO G. GUTIÉRREZ Abstract The persistence of rainforest patches at Fray Jorge National Park (FJNP) in semiarid Chile (30°40,S), a region receiving approximately 147 mm of annual rainfall, has been a source of concern among forest managers. These forests are likely dependent on water inputs from oceanic fog and their persistence seems uncertain in the face of climate change. Here, we assessed tree radial growth and establishment during the last two centuries and their relation to trends in climate and canopy disturbance. Such evaluation is critical to understanding the dynamics of these semiarid ecosystems in response to climate change. We analyzed forest structure of six forest patches (0.2,22 ha) in FJNP based on sampling within 0.1 ha permanent plots. For the main canopy species, the endemic Aextoxicon punctatum (Aextoxicaceae), we used tree-ring analysis to assess establishment periods, tree ages, growing trends and their relation to El Niño Southern Oscillation (ENSO), rainfall, and disturbance. The population dynamics of A. punctatum can be described by a continuous regeneration mode. Regeneration of A. punctatum was sensitive to different canopy structures. Growth release patterns suggest the absence of large scale human impact. Radial growth and establishment of A. punctatum were weakly correlated with rainfall and ENSO. If water limits forests patch persistence, patches are likely dependent on the combination of fog and rain water inputs. Forest patches have regenerated continuously for at least 250 years, despite large fluctuations in rainfall driven by ENSO and a regional decline in rainfall during the last century. Because of the positive influence on fog interception, forest structure should be preserved under any future climate scenario. Future research in FJNP should prioritize quantifying the long-term trends of fog water deposition on forests patches. Fog modeling is crucial for understanding the interplay among physical drivers of water inputs under climate change. [source] Recovery from bark harvesting of 12 medicinal tree species in Benin, West AfricaJOURNAL OF APPLIED ECOLOGY, Issue 3 2009Claire Delvaux Summary 1The growing interest in medicinal plants from both international industry and local markets requires management of tree bark harvesting from natural forests in order to prevent inappropriate exploitation of target species. This study was designed to determine the bark re-growth response of a selected number of medicinal tree species as a basis for the development of an optimal bark harvesting method. 2In 2004, bark was harvested from 925 trees belonging to 12 species in 38 sites in a dry forest in Benin, West Africa. Two years later, the response of trees to bark harvesting was examined with respect to re-growth (edge or sheet), development of vegetative growth around the wound, and the sensitivity of the wound to insect attack. 3Two species, Khaya senegalensis and Lannea kerstingii, showed complete wound recovery by edge growth. At the other extreme, Afzelia africana, Burkea africana and Maranthes polyandra had very poor edge growth. M. polyandra showed good sheet growth, whereas the other 11 species had none or poor sheet growth after total bark harvesting. In contrast, partial bark removal allowed better sheet growth in all 12 species studied. 4Insect sensitivity was species-specific. Insect attacks were negatively correlated with non-recovered wound area, but there was a marked species effect for the same rate of regeneration. L. kerstingii and K. senegalensis had very good and similar re-growth, but L. kerstingii was very susceptible to insect attack, whereas K. senegalensis appeared to be very resistant. Only a few individuals developed vegetative growth, and each tree usually developed only one or two agony shoots, but there was no significant difference between species. 5Synthesis and applications. This is the first study to provide data on the ability of trees to close wounds after bark harvesting in West Africa. We report large variability in the response of different species to our bark harvesting technique, and identify just two out of the 12 study species as suitable for sustainable bark harvesting. Based on our results, we developed a decisional step method to help forest managers select the best techniques for managing medicinal tree species as an alternative to bark harvesting, for example, coppice management, harvesting leaves instead of bark, stand establishment, and collaboration with timber companies. [source] Habitat assessment for a rare, arboreal forest mammal, the tree hyrax Dendrohyrax arboreusAFRICAN JOURNAL OF ECOLOGY, Issue 2 2001A. Gaylard Abstract Recent findings have suggested that there has been a change in the structural nature of forests in the Eastern Cape, South Africa, which explains decreases in forest fauna. One of these (rare) forest species is the tree hyrax Dendrohyrax arboreus, a nocturnal, arboreal folivore, which makes use of cavity-bearing trees as dens. However, a conflict exists between the use of forest resources and in protecting habitats for the tree hyrax. In order to design appropriate management strategies, conservation authorities and forest managers require information regarding the specific habitat requirements of fauna in their forest, particularly those that are already threatened by resource use. The aims of this study were thus: (i) to characterise the den trees of D. arboreus, (ii) to determine whether D. arboreus selects for certain den tree characteristics (i.e. relative to the abundance of that characteristic); and (iii) to develop a habitat assessment model for D. arboreus. The tree hydrax was found to select for den trees with particular characteristics: seven tree species were selected as den trees, which were usually the tallest trees in the canopy (4,8 m). Den trees were usually only partly decayed, with multiple cavity entrances and trunk angles of between 45° and 68°. Cavity entrance and orientation did not appear to play a role in den tree selection by D. arboreus. A function which discriminated between den trees and non-den trees was calculated, and can be used to determine the suitability of a tree as a den for a tree hyrax (and thus to prevent it from being removed during commercial logging operations), or to assess the suitability of an area for habitation by tree hyraxes. This model can therefore help to alleviate the conflict between forest conservation managers and resource users in the Eastern Cape. Résumé Des découvertes récentes laissent entendre qu'il y a eu des changements dans la nature structurelle des forêts du Cap oriental, en Afrique du Sud, qui expliquent le déclin de la faune forestière. Une de ces (rares) espèces forestières est le daman des arbres, Dendrohyrax arboreus, un nocturne arboricole, mangeur de feuilles, qui utilise les cavités dans les arbres comme terriers. Cependant, il existe un conflit entre l'utilisation des ressources forestières et la protection de l'habitat des damans des arbres. Afin de concevoir une stratégie de gestion adéquate, les autorités de la conservation et les gestionnaires forestiers ont besoin d'informations sur les exigences spécifiques en matière d'habitat de la faune de leurs forêts et particulièrement des espèces qui sont déjà menacées par l'utilisation des ressources. Les buts de cette étude étaient donc : (i) de caractériser les arbres qui servent de refuge àD. arboreus, (ii) de déterminer si D .arboreus choisit certaines caractéristiques des arbres qui lui servent d'abris (i.e. en fonction de l'abondance de cette caractéristique) et (iii) de mettre au point un modèle d'évaluation de l'habitat pour D. arboreus. On a découvert que le daman choisissait comme refuge des arbres qui avaient certaines caractéristiques : sept espèces d'arbres étaient choisies comme abris, qui étaient d'habitude les plus hauts arbres de la canopée (4 ,,8 m). Les arbres choisis n'étaient d'habitude que partiellement abîmés, avec des nombreuses entrées vers des creux et des troncs formant un angle compris entre 45° et 68°. L'entrée et l'orientation de la cavité ne semblaient pas jouer un rôle dans le choix de l'arbre par D. arboreus. On a calculé une fonction qui faisait la distinction entre les arbres qui servaient d'abris et les autres et qui peut servir à déterminer si un arbre convient pour servir d'abri à un daman des arbres (et donc à empêcher de le supprimer lors des opérations d'abattage commercial), ou àévaluer si une zone convient comme habitat pour les damans des arbres. Ce modèle peut donc aider à réduire les conflits entre les responsables de la conservation des forêts et ceux qui veulent en utiliser les ressources au Cap oriental. [source] The Delphi process , an expert-based approach to ecological modelling in data-poor environmentsANIMAL CONSERVATION, Issue 1 2006D. C. MacMillan Abstract Resource managers are involved in difficult decisions that affect rare species and habitats but often lack relevant ecological knowledge and experience. Ecological models are increasingly being looked to as a means of assisting the decision-making process, but very often the data are missing or are unsuited to empirical modelling. This paper describes the development and application of the Delphi approach to develop a decision support tool for wildlife conservation and management. The Delphi process is an expert-based approach to decision support that can be used as a means for predicting outcomes in situations where ,absolute' or ,objective' models are unavailable or compromised by lack of appropriate data. The method aims to develop consensus between experts over several rounds of deliberation on the assumption that combining the expertise of several individuals will provide more reliable results than consulting one or two individuals. In this paper the approach is used to engineer soft knowledge on the conservation requirements of capercaillie Tetrao urogallus, an endangered woodland grouse, into a model that can be used by forests managers to improve the quality of forest habitat for capercaillie over extensive commercial forest areas. This paper concludes with a discussion of the potential advantages and disadvantages of Delphi and other soft knowledge approaches to ecological modelling and conservation management. [source] | ||||||||||