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1.
Conserv Biol ; 33(2): 456-468, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30465331

RESUMEN

Although evidence-based approaches have become commonplace for determining the success of conservation measures for the management of threatened taxa, there are no standard metrics for assessing progress in research or management. We developed 5 metrics to meet this need for threatened taxa and to quantify the need for further action and effective alleviation of threats. These metrics (research need, research achievement, management need, management achievement, and percent threat reduction) can be aggregated to examine trends for an individual taxon or for threats across multiple taxa. We tested the utility of these metrics by applying them to Australian threatened birds, which appears to be the first time that progress in research and management of threats has been assessed for all threatened taxa in a faunal group at a continental scale. Some research has been conducted on nearly three-quarters of known threats to taxa, and there is a clear understanding of how to alleviate nearly half of the threats with the highest impact. Some management has been attempted on nearly half the threats. Management outcomes ranged from successful trials to complete mitigation of the threat, including for one-third of high-impact threats. Progress in both research and management tended to be greater for taxa that were monitored or occurred on oceanic islands. Predation by cats had the highest potential threat score. However, there has been some success reducing the impact of cat predation, so climate change (particularly drought), now poses the greatest threat to Australian threatened birds. Our results demonstrate the potential for the proposed metrics to encapsulate the major trends in research and management of both threats and threatened taxa and provide a basis for international comparisons of evidence-based conservation science.


Medidas de Progreso en el Entendimiento y el Manejo de las Amenazas que Enfrentan las Aves Australianas Resumen Aunque los métodos basados en evidencias se han vuelto muy comunes para la determinación del éxito de las medidas de conservación del manejo de los taxones amenazados, hoy en día no existen medidas estandarizadas para la evaluación del progreso de la investigación o el manejo. Desarrollamos cinco medidas para cumplir con esta necesidad que tienen los taxones amenazados y para cuantificar la necesidad de una mayor acción y un alivio efectivo de las amenazas. Estas medidas (falta de investigación, éxito de la investigación, falta de manejo, éxito del manejo y porcentaje de reducción de amenazas) pueden agregarse para examinar las tendencias de un taxón individual o las tendencias de las amenazas para múltiples taxones. Probamos la utilidad de estas medidas por medio de su aplicación en aves australianas amenazadas, que parece ser la primera vez que se evalúa el progreso en la investigación y en el manejo de amenazas para el caso de varios taxones amenazados dentro de un grupo faunístico a escala continental. Se ha realizado algún tipo de investigación sobre casi tres cuartas partes de las amenazas conocidas para los taxones, y hay un claro entendimiento de cómo aliviar casi la mitad de las amenazas con el impacto más alto. Se ha intentado algún tipo de manejo con casi la mitad de las amenazas. Los resultados del manejo variaron desde ensayos exitosos hasta la mitigación completa de la amenaza, incluso para un tercio de las amenazas de alto impacto. Tanto el progreso en la investigación como en el manejo tendió a ser mayor para los taxones que estaban siendo monitoreados, o que ocurrían en islas oceánicas. La depredación por gatos tuvo el puntaje más como amenaza potencial. Sin embargo, ha habido poco de éxito en la reducción del impacto de la depredación por gatos, así que ahora el cambio climático (particularmente la sequía) es la mayor amenaza para las aves amenazadas en Australia. Nuestros resultados demuestran el potencial que tienen las medidas propuestas de encapsular las tendencias más importantes en la investigación y en el manejo tanto de las amenazas como de los taxones amenazados y de proporcionar una base para comparaciones internacionales de la ciencia de la conservación basada en evidencias.


Asunto(s)
Conservación de los Recursos Naturales , Especies en Peligro de Extinción , Animales , Australia , Biodiversidad , Aves , Gatos , Islas
2.
J Environ Manage ; 223: 668-675, 2018 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-29975894

RESUMEN

Targeted threatened species management is a central component of efforts to prevent species extinction. Despite the development of a range of management frameworks to improve conservation outcomes over the past decade, threatened species management is still commonly characterised as ad hoc. Although there are notable successes, many management programs are ineffective, with relatively few species experiencing improvements in their conservation status. We identify underlying factors that commonly lead to ineffective and inefficient management. Drawing attention to some of the key challenges, and suggesting ways forward, may lead to improved management effectiveness and better conservation outcomes. We highlight six key areas where improvements are needed: 1) stakeholder engagement and communication; 2) fostering strong leadership and the development of achievable long-term goals; 3) knowledge of target species' biology and threats, particularly focusing on filling knowledge gaps that impede management, while noting that in many cases there will be a need for conservation management to proceed initially despite knowledge gaps; 4) setting objectives with measurable outcomes; 5) strategic monitoring to evaluate management effectiveness; and 6) greater accountability for species declines and failure to recover species to ensure timely action and guard against complacency. We demonstrate the importance of these six key areas by providing examples of innovative approaches leading to successful species management. We also discuss overarching factors outside the realm of management influence that can help or impede conservation success. Clear recognition of factors that make species' management more straightforward - or more challenging - is important for setting realistic management objectives, outlining strategic action, and prioritising resources. We also highlight the need to more clearly demonstrate the benefit of current investment, and communicate that the risk of under-investment is species extinctions. Together, improvements in conservation practice, along with increased resource allocation and re-evaluation of the prioritisation of competing interests that threaten species, will help enhance conservation outcomes for threatened species.


Asunto(s)
Conservación de los Recursos Naturales , Especies en Peligro de Extinción , Animales , Australia , Extinción Biológica , Riesgo
3.
Ecol Appl ; 27(8): 2369-2381, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-28851094

RESUMEN

Management guidelines for many fire-prone ecosystems highlight the importance of maintaining a variable mosaic of fire histories for biodiversity conservation. Managers are encouraged to aim for fire mosaics that are temporally and spatially dynamic, include all successional states of vegetation, and also include variation in the underlying "invisible mosaic" of past fire frequencies, severities, and fire return intervals. However, establishing and maintaining variable mosaics in contemporary landscapes is subject to many challenges, one of which is deciding how the fire mosaic should be managed following the occurrence of large, unplanned wildfires. A key consideration for this decision is the extent to which the effects of previous fire history on vegetation and habitats persist after major wildfires, but this topic has rarely been investigated empirically. In this study, we tested to what extent a large wildfire interacted with previous fire history to affect the structure of forest, woodland, and heath vegetation in Booderee National Park in southeastern Australia. In 2003, a summer wildfire burned 49.5% of the park, increasing the extent of recently burned vegetation (<10 yr post-fire) to more than 72% of the park area. We tracked the recovery of vegetation structure for nine years following the wildfire and found that the strength and persistence of fire effects differed substantially between vegetation types. Vegetation structure was modified by wildfire in forest, woodland, and heath vegetation, but among-site variability in vegetation structure was reduced only by severe fire in woodland vegetation. There also were persistent legacy effects of the previous fire regime on some attributes of vegetation structure including forest ground and understorey cover, and woodland midstorey and overstorey cover. For example, woodland midstorey cover was greater on sites with higher fire frequency, irrespective of the severity of the 2003 wildfire. Our results show that even after a large, severe wildfire, underlying fire histories can contribute substantially to variation in vegetation structure. This highlights the importance of ensuring that efforts to reinstate variation in vegetation fire age after large wildfires do not inadvertently reduce variation in vegetation structure generated by the underlying invisible mosaic.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales , Bosques , Incendios Forestales , Territorio de la Capital Australiana , Ecosistema , Nueva Gales del Sur
4.
Oecologia ; 179(1): 237-48, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25935217

RESUMEN

Altered disturbance regimes are a major driver of biodiversity loss worldwide. Maintaining or re-creating natural disturbance regimes is therefore the focus of many conservation programmes. A key challenge, however, is to understand how co-occurring disturbances interact to affect biodiversity. We experimentally tested for the interactive effects of prescribed fire and large macropod herbivores on the web-building spider assemblage of a eucalypt forest understorey and investigated the role of vegetation in mediating these effects using path analysis. Fire had strong negative effects on the density of web-building spiders, which were partly mediated by effects on vegetation structure, while negative effects of large herbivores on web density were not related to changes in vegetation. Fire amplified the effects of large herbivores on spiders, both via vegetation-mediated pathways and by increasing herbivore activity. The importance of vegetation-mediated pathways and fire-herbivore interactions differed for web density and richness and also differed between web types. Our results demonstrate that for some groups of web-building spiders, the effects of co-occurring disturbance drivers may be mostly additive, whereas for other groups, interactions between drivers can amplify disturbance effects. In our study system, the use of prescribed fire in the presence of high densities of herbivores could lead to reduced densities and altered composition of web-building spiders, with potential cascading effects through the arthropod food web. Our study highlights the importance of considering both the independent and interactive effects of disturbances, as well as the mechanisms driving their effects, in the management of disturbance regimes.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Ecosistema , Monitoreo del Ambiente/métodos , Incendios , Herbivoria/fisiología , Arañas/crecimiento & desarrollo , Animales , Australia , Biodiversidad , Eucalyptus/crecimiento & desarrollo , Cadena Alimentaria
5.
Conserv Biol ; 28(6): 1594-603, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25048948

RESUMEN

Biodiversity surrogates and indicators are commonly used in conservation management. The focal species approach (FSA) is one method for identifying biodiversity surrogates, and it is underpinned by the hypothesis that management aimed at a particular focal species will confer protection on co-occurring species. This concept has been the subject of much debate, in part because the validity of the FSA has not been subject to detailed empirical assessment of the extent to which a given focal species actually co-occurs with other species in an assemblage. To address this knowledge gap, we used large-scale, long-term data sets of temperate woodland birds to select focal species associated with threatening processes such as habitat isolation and loss of key vegetation attributes. We quantified co-occurrence patterns among focal species, species in the wider bird assemblage, and species of conservation concern. Some, but not all, focal species were associated with high levels of species richness. One of our selected focal species was negatively associated with the occurrence of other species (i.e., it was an antisurrogate)-a previously undescribed property of nominated focal species. Furthermore, combinations of focal species were not associated with substantially elevated levels of bird species richness, relative to levels associated with individual species. Our results suggest that although there is some merit to the underpinning concept of the FSA, there is also a need to ensure that actions are sufficiently flexible because management tightly focused on a given focal species may not benefit some other species, including species of conservation concern, such of which might not occur in species-rich assemblages.


Asunto(s)
Distribución Animal , Biodiversidad , Aves/fisiología , Conservación de los Recursos Naturales/métodos , Bosques , Animales , Nueva Gales del Sur
6.
Mol Ecol ; 22(5): 1267-81, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23379886

RESUMEN

Species that specialize in disturbed habitats may have considerably different dispersal strategies than those adapted to more stable environments. However, little is known of the dispersal patterns and population structure of such species. This information is important for conservation because many postfire specialists are at risk from anthropogenic changes to natural disturbance regimes. We used microsatellite markers to assess the effect of landscape variation and recent disturbance history on dispersal by a small mammal species that occupies the early seral stage of vegetation regeneration in burnt environments. We predicted that a postfire specialist would be able to disperse over multiple habitat types (generalist) and not exhibit sex-biased dispersal, as such strategies should enable effective colonization of spatially and temporally variable habitat. We found significant differentiation between sites that fitted an isolation-by-distance pattern and spatial autocorrelation of multilocus genotypes to a distance of 2-3 km. There was no consistent genetic evidence for sex-biased dispersal. We tested the influence of different habitat- and fire-specific landscape resistance scenarios on genetic distance between individuals and found a significant effect of fire. Our genetic data supported recently burned vegetation having greater conductance for gene flow than unburnt habitat, but variation in habitat quality between vegetation types and occupied patches had no effect on gene flow. Postfire specialists must evolve an effective dispersal ability to move over distances that would ensure access to early successional stage vegetation. Natural disturbance and natural heterogeneity may therefore not influence population genetic structure as negatively as expected.


Asunto(s)
Ambiente , Variación Genética , Roedores/genética , Animales , Cruzamiento , Bases de Datos Genéticas , Ecosistema , Femenino , Flujo Génico , Sitios Genéticos , Genotipo , Masculino , Ratones , Repeticiones de Microsatélite , Filogeografía , Análisis de Secuencia de ADN
7.
Proc Natl Acad Sci U S A ; 107(51): 21957-62, 2010 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-21098660

RESUMEN

Ecological "surprises" are defined as unexpected findings about the natural environment. They are critically important in ecology because they are catalysts for questioning and reformulating views of the natural world, help shape assessments of the veracity of a priori predictions about ecological trends and phenomena, and underpin questioning of effectiveness of resource management. Despite the importance of ecological surprises, major gaps in understanding remain about how studies might be done differently or done better to improve the ability to identify them. We outline the kinds of ecological surprises that have arisen from long-term research programs that we lead in markedly different ecosystems around the world. Based on these case studies, we identify important lessons to guide both existing studies and new investigations to detect ecological surprises more readily, better anticipate unusual ecological phenomena, and take proactive steps to plan for and alleviate "undesirable" ecological surprises. Some of these lessons include: (i) maintain existing, and instigate new, long-term studies; (ii) conduct a range of kinds of parallel and concurrent research in a given target area; (iii) better use past literature and conceptual models of the target ecosystem in posing good questions and developing hypotheses and alternative hypotheses; and (iv) increase the capacity for ecological research to take advantage of opportunities arising from major natural disturbances. We argue that the increased anticipatory capability resulting from these lessons is critical given that ecological surprises may become more prevalent because of climate change and multiple and interacting environmental stressors.


Asunto(s)
Conservación de los Recursos Naturales , Ecología/métodos , Ecosistema , Ecología/tendencias
8.
J Environ Manage ; 105: 66-75, 2012 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-22531752

RESUMEN

Wildfires pose significant risks to people and human infrastructure worldwide. The treatment of fuel in landscapes may alter these risks but the magnitude of this effect on risk is poorly understood. Evidence from Australian Eucalyptus forests suggests that mitigation of risk using prescribed burning as a fuel treatment is partial because weather and fuel dynamics are conducive to regular high intensity fires. We further examine the response of risk to treatment in eucalypt forests using landscape simulation modelling. We model how five key measures of wildfire activity that govern risk to people and property may respond to variations in rate and spatial pattern of prescribed fire. We then model effects of predicted climate change (2050 scenarios) to determine how the response of risk to treatment is likely to be altered in the future. The results indicate that a halving of risk to people and property in these forests is likely to require treatment rates of 7-10% of the area of the landscape per annum. Projections of 2050 weather conditions under climate change further substantially diminished the effect of rate of treatment. A large increase in rates of treatment (i.e. circa. 50% over current levels) would be required to counteract these effects of climate change. Such levels of prescribed burning are unlikely to be financially feasible across eucalypt dominated vegetation in south eastern Australia. Despite policy imperatives to expand fuel treatment, a reduction rather than an elimination of risk will result. Multi-faceted strategies will therefore be required for the management of risk.


Asunto(s)
Ecosistema , Eucalyptus , Incendios , Modelos Biológicos , Australia , Simulación por Computador , Conservación de los Recursos Naturales/métodos , Agricultura Forestal/métodos , Medición de Riesgo
9.
Conserv Biol ; 22(5): 1309-19, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18680500

RESUMEN

Mature trees scattered throughout agricultural landscapes are critical habitat for some biota and provide a range of ecosystem services. These trees are declining in intensively managed agricultural landscapes globally. We developed a simulation model to predict the rates at which these trees are declining, identified the key variables that can be manipulated to mitigate this decline, and compared alternative management proposals. We used the initial numbers of trees in the stand, the predicted ages of these trees, their rate of growth, the number of recruits established, the frequency of recruitment, and the rate of tree mortality to simulate the dynamics of scattered trees in agricultural landscapes. We applied this simulation model to case studies from Spain, United States, Australia, and Costa Rica. We predicted that mature trees would be lost from these landscapes in 90-180 years under current management. Existing management recommendations for these landscapes--which focus on increasing recruitment--would not reverse this trend. The loss of scattered mature trees was most sensitive to tree mortality, stand age, number of recruits, and frequency of recruitment. We predicted that perpetuating mature trees in agricultural landscapes at or above existing densities requires a strategy that keeps mortality among established trees below around 0.5% per year, recruits new trees at a rate that is higher than the number of existing trees, and recruits new trees at a frequency in years equivalent to around 15% of the maximum life expectancy of trees. Numbers of mature trees in landscapes represented by the case studies will decline before they increase, even if strategies of this type are implemented immediately. This decline will be greater if a management response is delayed.


Asunto(s)
Agricultura , Conservación de los Recursos Naturales/métodos , Ecosistema , Modelos Teóricos , Árboles/crecimiento & desarrollo , Australia , Simulación por Computador , Costa Rica , Dinámica Poblacional , España , Estados Unidos
10.
Int J Parasitol ; 28(5): 747-55, 1998 May.
Artículo en Inglés | MEDLINE | ID: mdl-9650054

RESUMEN

The effects of a reduction of parasite burdens were determined in adult female Mountain Brushtail Possums, Trichosurus caninus, on the birth, mortality and growth rates of pouch-dependent young, as well as the haematological and serum biochemical values of the mothers. The efficacy of the anthelmintic drug ivermectin for reducing parasite burdens in this host was assessed using faecal and necropsy examinations of a small number of animals. Ivermectin began to reduce parasite burdens by 48 h after treatment. In the second stage of the experiment, animals were treated or sham injected (control individuals) with ivermectin and praziquantel at 8-10-week intervals throughout the breeding season to the time of emergence of young from the pouch. Treatment with ivermectin and praziquantel had no significant effect on the proportion of females giving birth, or on the survival of young to emergence. An effect of treatment was recorded for absolute eosinophil counts in adult females, which, in spring; were higher among control animals than those that were treated.


Asunto(s)
Animales Salvajes/parasitología , Antihelmínticos/uso terapéutico , Helmintiasis Animal/tratamiento farmacológico , Parasitosis Intestinales/veterinaria , Marsupiales/parasitología , Animales , Australia , Tasa de Natalidad , Eosinófilos , Heces/parasitología , Femenino , Interacciones Huésped-Parásitos , Parasitosis Intestinales/tratamiento farmacológico , Ivermectina/uso terapéutico , Marsupiales/fisiología , Recuento de Huevos de Parásitos , Praziquantel/uso terapéutico , Embarazo , Complicaciones Parasitarias del Embarazo/tratamiento farmacológico , Complicaciones Parasitarias del Embarazo/veterinaria , Reproducción , Estaciones del Año
11.
J Wildl Dis ; 32(1): 142-6, 1996 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8627928

RESUMEN

Hematological and serum biochemical values were determined in a wild population of the mountain brushtail possum (Trichosurus caninus) at Cambarville, central Victoria, southeastern Australia. Animals were sampled during two-week trapping periods in June, September, and December 1992, and April 1993. Values for hemoglobin, red cell count and hematocrit were significantly higher in males than females. Total protein and mean corpuscular volume (MCV) were significantly higher in female T. caninus. Significant seasonal variations were detected for total bilirubin, alkaline phosphatase, total protein, albumin, urea, absolute eosinophils, MCV, sodium, potassium, and phosphate.


Asunto(s)
Animales Salvajes/sangre , Zarigüeyas/sangre , Fosfatasa Alcalina/sangre , Animales , Bilirrubina/sangre , Recuento de Células Sanguíneas/veterinaria , Análisis Químico de la Sangre/veterinaria , Proteínas Sanguíneas/análisis , Electrólitos/sangre , Femenino , Hematócrito/veterinaria , Hemoglobinas/análisis , Masculino , Valores de Referencia , Estaciones del Año , Caracteres Sexuales , Urea/sangre , Victoria
12.
J Wildl Dis ; 37(2): 370-4, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11310891

RESUMEN

Reference hematological and plasma biochemical values are presented for the greater glider (Petauroides volans) at Tumut (southeastern New South Wales, Australia). Nineteen animals were sampled during a capture period of 1 wk in August 1999. Values for red cell counts were significantly higher in male animals (mean +/- SE; males: 5.6 +/- 0.1; females: 5.2 +/- 0.1). Young animals had higher white cell counts than older ones (mean +/- SE; young: 4.9 +/- 0.4; older: 2.8 +/- 0.4). Lymphocytes were the predominant white blood cell type in this species.


Asunto(s)
Análisis Químico de la Sangre/veterinaria , Marsupiales/sangre , Animales , Australia , Recuento de Eritrocitos , Femenino , Hemoglobinas/análisis , Recuento de Linfocitos/veterinaria , Masculino , Valores de Referencia , Caracteres Sexuales
13.
Aust Vet J ; 72(6): 215-6, 1995 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8526814

RESUMEN

A combination of tiletamine hydrochloride and zolazepam hydrochloride in a 1:1 ration by weight was used successfully to sedate mountain brushtail possums, Trichosurus caninus, in the field. A standard total dose of 50 to 60 mg provided adequate sedation for the completion of a range of handling procedures. We describe the induction time, dose rate and side-effects associated with the use of tiletamine and zolazepam in T caninus.


Asunto(s)
Anestesia/veterinaria , Anestésicos Disociativos , Hipnóticos y Sedantes , Zarigüeyas/fisiología , Tiletamina , Zolazepam , Anestésicos Disociativos/administración & dosificación , Anestésicos Disociativos/efectos adversos , Animales , Temperatura Corporal/efectos de los fármacos , Quimioterapia Combinada , Femenino , Hipnóticos y Sedantes/administración & dosificación , Hipnóticos y Sedantes/efectos adversos , Inmovilización , Inyecciones Intramusculares/veterinaria , Masculino , Relajación Muscular/efectos de los fármacos , Respiración/efectos de los fármacos , Tiletamina/administración & dosificación , Tiletamina/efectos adversos , Factores de Tiempo , Zolazepam/administración & dosificación , Zolazepam/efectos adversos
14.
Conserv Biol ; 20(4): 1005-15, 2006 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16922217

RESUMEN

The two major forms of disturbance in the montane ash eucalypt forests of the Central Highlands of Victoria (southeastern Australia) are clearfell logging and unplanned wildfires. Since the 1930s wildfire has been followed by intensive and extensive salvage-logging operations, which may proceed for many years after a wildfire has occurred. Although applied widely, the potential effects of salvage logging on native flora and fauna have been poorly studied. Our data indicate that the abundance of large trees with hollows is significantly reduced in forests subject to salvage harvesting. This has implications for thepersistence of an array of such cavity-using vertebrates as the endangered arboreal marsupial, Leadbeater's possum (Gymnobelidues leadbeateri). Salvage logging also reduces the prevalence of multiaged montane ash forests--places that typically support the highest diversity of arboreal marsupials and forest birds. Limited research has been conducted on the effects of salvage logging on plants; thus, we constructed hypotheses about potential impacts for further testing based on known responses to clearfell logging and key life history attributes. We predict many species, such as vegetatively resprouting tree ferns, will decline, as they do after clearfelling. We also suggest that seed regenerators, which typically regenerate well after fire or conventional clearfelling, will decline after salvage logging because the stimulation for germination (fire) takes place prior to mechanical disturbance (logging). Understoryplant communities in salvage-logged areas will be dominated by a smaller suite of species, and those that are wind dispersed, have viable soil-stored seed remaining after salvage logging, or have deep rhizomes are likely to be advantaged. We recommend the following improvements to salvage-logging policies that may better incorporate conservation needs in Victorian montane ash forests: (1) exemption of salvage logging from some areas (e.g., old-growth stands and places subject to only partial stand damage); (2) increased retention of biological legacies on burned areas through variations in the intensity of salvage logging; and (3) reduction in the levels of physical disturbance on salvage-logged areas, especially through limited seedbed preparation and mechanical disturbance.


Asunto(s)
Biodiversidad , Eucalyptus/fisiología , Agricultura Forestal/métodos , Animales , Conservación de los Recursos Naturales/métodos , Marsupiales/fisiología , Árboles , Victoria
15.
Conserv Biol ; 20(4): 949-58, 2006 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16922212

RESUMEN

We summarize the documented and potential impacts of salvage logging--a form of logging that removes trees and other biological material from sites after natural disturbance. Such operations may reduce or eliminate biological legacies, modify rare postdisturbance habitats, influence populations, alter community composition, impair natural vegetation recovery, facilitate the colonization of invasive species, alter soil properties and nutrient levels, increase erosion, modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity These impacts can be assigned to three broad and interrelated effects: (1) altered stand structural complexity; (2) altered ecosystem processes and functions; and (3) altered populations of species and community composition. Some impacts may be different from or additional to the effects of traditional logging that is not preceded by a large natural disturbance because the conditions before, during, and after salvage logging may differ from those that characterize traditional timber harvesting. The potential impacts of salvage logging often have been overlooked, partly because the processes of ecosystem recovery after natural disturbance are still poorly understood and partly because potential cumulative effects of natural and human disturbance have not been well documented. Ecologically informed policies regarding salvage logging are needed prior to major natural disturbances so that when they occur ad hoc and crisis-mode decision making can be avoided. These policies should lead to salvage-exemption zones and limits on the amounts of disturbance-derived biological legacies (e.g., burned trees, logs) that are removed where salvage logging takes place. Finally, we believe new terminology is needed. The word salvage implies that something is being saved or recovered, whereas from an ecological perspective this is rarely the case.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales/métodos , Desastres , Agricultura Forestal , Árboles , Ecosistema , Agricultura Forestal/economía , Agricultura Forestal/legislación & jurisprudencia , Agricultura Forestal/métodos
16.
Mol Ecol ; 14(6): 1667-80, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15836641

RESUMEN

Dispersal is an important influence on species' distributions, patch colonization and population persistence in fragmented habitat. We studied the impacts of habitat fragmentation resulting from establishment of an exotic pine plantation on dispersal of the marsupial carnivore, Antechinus agilis. We applied spatial analyses of individual multilocus microsatellite genotypes and mitochondrial haplotypes to study patterns of gene flow in fragmented habitat and natural habitat 'control' areas, and how this is affected by the spatial dispersion of habitat patches, the presence of corridors and a 'mainland' source of migrants. Spatial analysis of molecular variance and partial Mantel tests confirmed the absence of cryptic barriers to gene flow in continuous habitat, which if present would confound the comparison of genetic structures in fragmented vs. unfragmented habitats. Spatial genotypic structure suggested that although dispersal was male-biased in both habitat types, fragmentation restricted dispersal of males more than that of females and the degree of restriction of male dispersal was dependent on the geographical isolation of the patch. The scale of positive genotypic structure in fragmented habitat was restricted to the two closest patches for females and the three closest patches for males. Our results provide evidence for significantly increased gene flow through habitat corridors relative to that across the matrix and for significantly lower gene flow between 'mainland' unfragmented habitat and habitat patches relative to that within either habitat type, suggesting a behavioural barrier to crossing habitat interfaces.


Asunto(s)
Demografía , Ambiente , Genética de Población , Marsupiales/genética , Animales , ADN Mitocondrial/genética , Femenino , Genotipo , Haplotipos/genética , Masculino , Repeticiones de Microsatélite/genética , Nueva Gales del Sur , Dinámica Poblacional , Factores Sexuales
17.
Mol Ecol ; 14(6): 1789-801, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15836650

RESUMEN

Habitat fragmentation is one of the major contributors to the loss of biodiversity worldwide. However, relatively little is known about its more immediate impacts on within-patch population processes such as social structure and mating systems, whose alteration may play an important role in extinction risk. We investigated the impacts of habitat fragmentation due to the establishment of an exotic softwood plantation on the social kin structure and breeding system of the Australian marsupial carnivore, Antechinus agilis. Restricted dispersal by males in fragmented habitat resulted in elevated relatedness among potential mates in populations in fragments, potentially increasing the risk of inbreeding. Antechinus agilis nests communally in tree hollows; these nests are important points for social contact between males and females in the mating season. In response to elevated relatedness among potential mates in fragmented habitat, A. agilis significantly avoided sharing nests with opposite-sex relatives in large fragment sites (but not in small ones, possibly due to limited nest locations and small population sizes). Because opposite-sex individuals shared nests randomly with respect to relatedness in unfragmented habitat, we interpreted the phenomenon in fragmented habitat as a precursor to inbreeding avoidance via mate choice. Despite evidence that female A. agilis at high inbreeding risk selected relatively unrelated mates, there was no overall increased avoidance of related mates by females in fragmented habitats compared to unfragmented habitats. Simulations indicated that only dispersal, and not nonrandom mating, contributed to inbreeding avoidance in either habitat context. However, habitat fragmentation did influence the mating system in that the degree of multiple paternity was reduced due to the reduction in population sizes and population connectivity. This, in turn, reduced the number of males available to females in the breeding season. This suggests that in addition to the obvious impacts of reduced recruitment, patch recolonization and increased genetic drift, the isolation of populations in habitat patches may cause changes in breeding behaviour that contribute to the negative impacts of habitat fragmentation.


Asunto(s)
Ambiente , Endogamia , Marsupiales/fisiología , Comportamiento de Nidificación/fisiología , Conducta Sexual Animal/fisiología , Conducta Social , Animales , Simulación por Computador , Femenino , Masculino , Marsupiales/genética , Repeticiones de Microsatélite/genética , Nueva Gales del Sur , Dinámica Poblacional
18.
Environ Monit Assess ; 39(1-3): 543-57, 1996 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24198028

RESUMEN

The production of timber from native forests is presently one of the most controversial land management issues in Australia. Part of this controversy results from the potential impacts of forestry practices on forest-dependent fauna, particularly those that are rare and endangered, such as Leadbeater's Possum Gymnobelideus leadbeateri McCoy, in the forests of central Victoria, south-eastern Australia. A significant proportion of the highly limited distribution of this species overlaps with some of the most valuable wood production forests in Australia within which extensive clearfelling operations are employed to produce timber and pulpwood. These operations can destroy the habitat of G. leadbeateri. The Victoria government agency that is responsible for forest and wildlife management has devised a forest zoning system as part of the management strategies to conserve G. leadbeateri within timber production areas. This is designed to partition the forest into three types of areas: (1) where the conservation of G. leadbeateri is a priority, (2) where wood production is a priority, and, (3) where both land uses are a joint priority. The classification of areas of forest where the conservation of G. leadbeateri is the primary land use is based on an understanding of the habitat requirements of the species. The results of recent field studies, where statistical models of the habitat requirements of G. leadbeateri have been developed and their performance subsequently tested using a new dataset, highlights the need for a new basis to guide the classification of areas for the conservation of the species within wood production forests. We describe a method for devising a forest management zoning system that is based on a statistical model of the habitat requirements of G. leadbeateri and which will better integrate wood production and the conservation of the species. This procedure accounts for the uncertainty in the statistical model and, in turn, reduces the risk that areas where G. leadbeateri occurs are logged, whilst ensuring that other areas are not unnecessarily excluded from timber harvesting.

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