Commentary: Continental-level biodiversity collapse

Biodiversity loss is a global phenomenon, with Woinarski et al. providing a sobering review of the demise of the Australian native terrestrial mammal fauna. The authors’ focus is on the loss of >10% of endemic terrestrial native mammal fauna since European settlement in 1788. The extent of mammal loss is highlighted by the contrast with mainland North America, with just one mammal species extinction in the equivalent ∼200-y period. Woinarski et al. make key points about conservation policies and practices, some of which have global implications

Small patches make critical contributions to biodiversity conservation

Vast areas of the earth's land surface have been altered by human activities such as clearing native vegetation for agriculture and livestock grazing, logging of natural forests, and land conversion for urban settlements (1). These activities have had profound impacts on biodiversity and on key ecosystem processes (e.g. pollination and nutrient cycling) (2). Many ecosystems have been markedly reduced in extent (often termed habitat loss) (3, 4) with remaining areas sub-divided into small, isolated remnants (typically termed habitat fragmentation) (see (5)). In PNAS, Wintle et al. (6) explore some new perspectives associated with the conservation value of small, isolated remnants and demonstrate they are more important for biodiversity conservation than often recognized

The Variable Retention Harvest System and its implications for biodiversity in the Mountain Ash forests of the Central Highlands of Victoria

This report was commissioned by the Victorian Government through the Department of Primary Industries (DPI) in mid-2006. The aim of the report was to describe the impacts of timber harvesting activities on biodiversity in native forests. It was to focus on these impacts at a landscape level and describe opportunities for improving biodiversity and other outcomes through alternative approaches to timber harvesting. The report focuses on the highlyproductive, wet ash-type eucalypt forests of the Central Highlands of Victoria. The alternative silvicultural system described in this report is referred to as the Variable Retention Harvest System (VRHS) and involves the retention of strategic elements of the forest from one rotation to the next. The VRHS aims to maintain ecological functionality at a landscape level and is based on insights into ecologically appropriate harvesting methods being developed and adopted in the Pacific-Northwest of North America

Failing to conserve Leadbeater’s Possum and its Mountain Ash forest habitat

The conservation of the Critically Endangered Leadbeater’s Possum Gymnobelideus leadbeateri in Victoria’s Mountain Ash Eucalyptus regnans forests is one of the most controversial native mammal conservation issues in Australia. Much of the controversy results from long-running conflicts between the demands of the native forest logging industry and associated impacts on Leadbeater’s Possum and its Mountain Ash forest habitat. Here we argue that despite a legislative obligation to protect Leadbeater’s Possum and some limited recent improvements in management, conservation efforts for the species have gone backwards over the past decade. The key problems we identify include that the Victorian Government has: (1) maintained levels of wood production that are too high given the amount of the forest estate that was burned in 2009, (2) failed to substitute clearfell logging practices with more ecologically-sensitive Variable Retention Harvesting Systems, (3) ignored the science (including by its own researchers) on the need for a large protected area for Leadbeater’s Possum, (4) altered key definitions such as those for mature trees and old growth that have substantially weakened the ability to protect the species, and (5) overlooked the array of forest values beyond timber production (such as water and tourism) and which make a greater contribution to the economy. Our analyses suggest that populations of Leadbeater’s Possum are undergoing a substantial decline, as are other hollow-dependent species such as the Greater Glider Petauroides volans. Far more concerted efforts are needed to conserve not only Leadbeater’s Possum but also the Mountain Ash forests in which it presently occurs

The adequacy of Victoria's protected areas for conserving its forest-dependent fauna

Networks of protected areas are a key component of efforts to conserve biodiversity. However, there are concerns about an uncritical focus on the percentage area of reserves without an assessment of how well formal reserves are actually protecting biodiversity. We completed a spatial analysis of the formal reserve system in the Australian state of Victoria. We quantified how well the reserve system captured a crude surrogate for vegetation communities (viz: Ecological Vegetation Classes) as well as distribution models for an array of threatened forest-dependent species. We found evidence of a high degree of overlap between areas subject to intensive forestry (clearcutting) operations and the modelled distribution of a suite of forest dependent species. A key outcome of our study was that areas around sites subject to past logging as well as new areas proposed for logging under the Timber Release Plan in Victoria had significantly higher values for threatened forest dependent species (as determined by habitat distribution models) than areas that had not been logged. We found significant differences in the spatial characteristics of the dedicated reserve systems and informal protected area networks, with the latter featuring much of its area close to a tenure boundary where logging occurs. Our empirical analyses demonstrating the impacts of ongoing logging operations on areas with high environmental suitability for threatened species has important implications. In particular, the current reserve system is inadequate for a suite of forest-dependent taxa, including Critically Endangered Leadbeater’s Possum (Gymnobelideus leadbeateri) and the vulnerable Greater Glider (Petauroides volans). This suggests a high degree of conflict between areas of high value for conservation and areas targeted for wood production.Threatened Species Recovery Hub, National Environmental Science Progra

Where there is fire, there is smoke

In his In Depth News story “Scientists aim to smoke out wildfire impacts” (1 June, p. 948), W. Cornwall discusses wildfire-generated smoke and the associated large quantities of particulate matter. We agree that research on smoke demands more sustained scientific attention, particularly given its impacts on human communities [e.g., (1)]. However, not all fires are created equal in terms of their (natural or deliberate) origins, the amount of biomass they consume, and the amount of smoke they generate as a result. High-intensity wildfires (those exceeding 200,000 kW/m2) in very high biomass forests may consume 9 to 14% of the biomass (burning green parts of living trees but often leaving dense wood) or 40 to 58 tons per hectare (2). This is substantially less than half of the 140 to 450 tons of biomass per hectare consumed when logging slash (i.e., dense waste wood) is burned after logging operations in these same kinds of forest (3, 4). Moreover, such logging burns consume at least 10 times as much biomass as hazard reduction burns designed to reduce wildfire risk (5). The smoke generated from logging therefore represents a substantial form of industrial pollution, but it is not treated as such. Beyond improving efforts to quantify the chemical composition of smoke and its long-term impacts on human health, there is an urgent need to examine the problem in a more holistic manner. This demands far more careful consideration of the origins of smoke, the relative amounts of smoke originating from different kinds of fires, and the forest and land use policies that generate smoke (and might reduce it)

Ranking Conservation And Timber Management Options For Leadbeater's Possum In Southeastern Australia Using Population Viability Analysis

The conservation of the endangered Leadbeater's Possum, Gymnobelideus leadbeateri, is one of the most contentious forestry issues in Australia. The challenge is to identify strategies to conserve the species in the significant portion of its range in the central highlands of Victoria (southeastern Australia) where timber harvesting occurs. We used ALEX, a simulation program for population viability analysis, to explore the effectiveness of potential forest management strategies to enhance the persistence of G. leadbeateri in areas of wood production. Our study focused on the relationship between the risk of metapopulation extinction and (1) the number and spatial arrangement of 50-ha logging areas that could be reserved from timber harvesting and (2) the impacts of post-fire salvage logging in reserved areas. We modeled complex patch structures within two forest blocks (Murrindindi and Steavenson) that were based on maps of both existing patches of suitable habitat for G. leadbeateri and the location of potential logging areas. We recorded high values for the probability of extinction of metapopulations of G. leadbeateri when existing strategies for the conservation of the species within the Murrindindi and Steavenson Forest Blocks were modeled. Exclusion of salvage logging operations from burned, old-growth forests significantly improved the species' prospects of survival in both the short and long term. Withdrawal of timber harvesting from some proposed logging coupes made a significant, positive long-term contribution to metapopulation persistence. But there will be a delay of at least 150 years until areas set aside now make a significant contribution to metapopulation persistence. This is the time required for existing stands of regrowth to develop old-growth characteristics that are an essential habitat component for G. leadbeateri. We examined the effectiveness of different designs for setting aside a total reserved area of 300 ha. These ranged from a single 300-ha reserve to 12, 25-ha reserves. Populations in smaller reserves were vulnerable to extinction from demographic stochasticity and environmental variability. Conversely, a small number of larger reserves were susceptible to destruction in a single, catastrophic wildfire, highlighting the need for several dispersed reserves. Analyses of the sensitivity of various management options to variations in fire frequency and extent, movement capability, and a wide range of other factors indicated that the conservation strategy that gave the best relative outcome for G. leadbeateri was both to set aside several 50 to 100-ha reserves in every forest block and to preclude post-fire salvage logging operations from these areas if they burned in a wildfire

Risks of fire and the management of catchments for timber production and urban water supply

While previous studies have examined how forest management is influenced by the risk of fire, they rely on probabilistic estimates of the occurrence and impacts of fire. However, nonprobabilistic approaches are required for assessing the importance of fire risk when data are poor but risks are appreciable. We explore impacts of fire risk on forest management using as a case study a water catchment in the Australian Capital Territory (south-eastern Australia). In this forested area, urban water supply and timber yields from exotic plantations are potential joint but also competing land uses. Our analyses were stimulated by extensive wildfires in early 2003 that burned much of the existing exotic pine plantation estate in the water catchment and the resulting need to explore the relative economic benefits of revegetating the catchment with exotic plantations or native vegetation. The current mean fire interval in the ACT is approximately 40 years, making the establishment of a pine plantation economically marginal at a 4% discount rate. However, the relative impact on water yield of revegetation with native species and pines is very uncertain, as is the risk of fire under climate change. We use info-gap decision theory to account for these nonprobabilistic sources of uncertainty, demonstrating that the decision that is most robust to uncertainty is highly sensitive to the cost of native revegetation. If costs of native revegetation are sufficiently small, this option is more robust to uncertainty than revegetation with a commercial pine plantation

The difficulties of systematic reviews

The need for robust evidence to support conservation actions has driven the adoption of systematic approaches to research synthesis in ecology. However, applying systematic review to complex or open questions remains challenging, and this task is becoming more difficult as the quantity of scientific literature increases. We drew on the science of linguistics for guidance as to why the process of identifying and sorting information during systematic review remains so labor intensive, and to provide potential solutions. Several linguistic properties of peer-reviewed corpora-including nonrandom selection of review topics, small-world properties of semantic networks, and spatiotemporal variation in word meaning-greatly increase the effort needed to complete the systematic review process. Conversely, the resolution of these semantic complexities is a common motivation for narrative reviews, but this process is rarely enacted with the rigor applied during linguistic analysis. Therefore, linguistics provides a unifying framework for understanding some key challenges of systematic review and highlights 2 useful directions for future research. First, in cases where semantic complexity generates barriers to synthesis, ecologists should consider drawing on existing methods-such as natural language processing or the construction of research thesauri and ontologies-that provide tools for mapping and resolving that complexity. These tools could help individual researchers classify research material in a more robust manner and provide valuable guidance for future researchers on that topic. Second, a linguistic perspective highlights that scientific writing is a rich resource worthy of detailed study, an observation that can sometimes be lost during the search for data during systematic review or meta-analysis. For example, mapping semantic networks can reveal redundancy and complementarity among scientific concepts, leading to new insights and research questions. Consequently, wider adoption of linguistic approaches may facilitate improved rigor and richness in research synthesis.Australian Research Council. Grant Number: fl12010010