Author Index

Authors Index

Author Index     

Effects of multiple fires on tree invasion in montane grasslands

There is circumstantial evidence that grasslands on the Bunya Mountains were once maintained by Aboriginal burning, and with lack of fire under European management are being colonised by trees. To assess the efficacy of burning for maintaining grasslands, 119 fires were lit between 1996 and 2006. The total area of unburnt grasslands decreased by 27%, while grasslands burnt at least once decreased by 1%. The density of invading trees was recorded from fixed plots on 23 grasslands burnt between one and six times. Cassinia was virtually eliminated and the density of the Rainforest species guild slowly but continually declined. Acacia irrorata exhibited a humped response, with initial increases resulting from vegetative resprouting and gradual decline with persistent burning. Phyllodinous Acacia and Woodland trees were the least fire sensitive guilds, having stable or increased density with repeated burning. Multi-factor regression modelling detected no significant relationships between changes in woody plant density and the interval between fires, fire intensity, the initial density of large trees, an index of soil moisture, or the cumulative number of fires for any species guild. The survivorship of both Cassinia and Rainforest guilds was significantly lower with summer burning than winter burning, but a seasonal effect of burning was not evident for other guilds. The findings suggest that regardless of fire conditions, frequent burning will reduce the number of adult trees, maintain resprouts in an immature state, facilitate further fire and reduce the rate of grassland loss. Woodland species are especially resilient to fire, and burning to maintain grassy ecosystems will be most successful where the main colonisers are rainforest species and burning is conducted in summer. The findings suggest that the montane grasslands of the Bunya Mountains were maintained by anthropogenic burning and active fire management will prolong their existence.     

The economic impacts to commercial farms from invasive monkeys in Puerto Rico

Beginning in the 1930s and continuing through the 1970s, rhesus macaques and patas monkeys were introduced to presumed secure locations, primarily coastal islets, in Puerto Rico. Escapes into the wild began almost immediately after introduction. Today the combined range of the two species covers approximately 600 km² of southwestern Puerto Rico, where serious conflicts with agricultural interests have resulted. The Puerto Rico Department of Agriculture surveyed about 90% of commercial farmers in the range of the monkeys to begin quantifying damage by monkeys and the associated economic losses during the years 2002–2006. During that time, total economic losses by commercial farmers to monkeys increased from $1.13 million USD to over $1.46 million per year. Of these amounts, the economic losses due to farmers avoiding monkey damage by switching from fruit and vegetable crops to less rewarding land use (primarily hay or pastureland) increased from $490,000 to $1.33 million per year. The losses reported from the survey represent only a portion of economic losses to the invasive monkeys. Subsistence and other smaller farms and agriculture were not included in the survey. We also discuss many other economic issues surrounding the impacts of the invasive monkeys, but for which sufficient data are not available for economic analyses. These include concerns such as destruction of native (especially endangered) wildlife, threat of disease spread, and property damage, all of which would also have to be considered to fully evaluate invasive monkey economic impacts in Puerto Rico.     

Monetary Valuation Methods for Economic Analysis of the Benefit-Costs of Protecting Rare Wildlife Species from Predators

Many threatened and endangered species are negatively impacted by predation. Management of the predators that are geographically and temporally in position to threaten species of concern can greatly aid in their conservation. However, decisions on management strategies are based within economic constraints, while the success of management actions is measured by wildlife resource improvement. Here, we review methods for applying monetary valuations for threatened and endangered species so that economic analyses of management actions can be used to help guide and evaluate management decisions. A variety of applied examples are provided to demonstrate the principles. This revised version was published online in July 2006 with corrections to the Cover Date.     

One Health as a moral dilemma: Towards a socially responsible zoonotic disease control

During the last decade, the concept of One Health has become the international standard for zoonotic disease control. This call for transdisciplinary collaboration between professionals in human, animal and environmental health has produced several successes in zoonotic disease control, surveillance and research. Despite the lack of a clear definition, a shared agenda or institutional governance, One Health has proven to be a fruitful idea. Due to its ambiguity, the One Health concept functions as a boundary object: by leaving room for interpretation to fit different purposes, it facilitates cooperation. In many cases, this results in the promotion of health of humans, animals and the environment. However, there are also situations in which this mutual benefit of a One Health approach is not that evident, for instance, when healthy animals are culled to protect public health. Although such a strategy could well be part of a One Health approach, it is hard to understand how this contributes to the health of concerning animals. Consequently, these practices often lead to public debate. This raises questions on how we should understand the One Health concept in zoonotic disease control. Is it really about equally improving the health of humans, animals and the environment and is this even possible? Or is it ultimately just public health that counts? In cases of conflict between different values, the lack of a universal definition of the One Health concept contributes to this complexity. Although boundary objects have many positive aspects, in the context of One Health and zoonotic disease control, this conception seems to conceal underlying normative differences. To address moral dilemmas related to a One Health approach in zoonotic disease control, it is important to reflect on moral status and the meaning of health for humans, animals and the environment.     

Langerhans cells facilitate epithelial DNA damage and squamous cell carcinoma

Polyaromatic hydrocarbons (PAHs) are prevalent, potent carcinogens, and 7,12-dimethylbenz[a]anthracene (DMBA) is a model PAH widely used to study tumorigenesis. Mice lacking Langerhans cells (LCs), a signatory epidermal dendritic cell (DC), are protected from cutaneous chemical carcinogenesis, independent of T cell immunity. Investigation of the underlying mechanism revealed that LC-deficient skin was relatively resistant to DMBA-induced DNA damage. LCs efficiently metabolized DMBA to DMBA-trans-3,4-diol, an intermediate proximal to oncogenic Hras mutation, and DMBA-treated LC-deficient skin contained significantly fewer Hras mutations. Moreover, DMBA-trans-3,4-diol application bypassed tumor resistance in LC-deficient mice. Additionally, the genotoxic impact of DMBA on human keratinocytes was significantly increased by prior incubation with human-derived LC. Thus, tissue-associated DC can enhance chemical carcinogenesis via PAH metabolism, highlighting the complex relation between immune cells and carcinogenesis.     

Epithelial-to-mesenchymal transition generates proliferative human islet precursor cells

Insulin-expressing beta cells, found in pancreatic islets, are capable of generating more beta cells even in the adult. We show that fibroblast-like cells derived from adult human islets donated postmortem proliferate readily in vitro. These mesenchymal-type cells, which exhibit no hormone expression, can then be induced to differentiate into hormone-expressing islet-like cell aggregates, which reestablishes the epithelial character typical of islet cells. Immunohistochemistry, in situ hybridization, and messenger RNA measurements in single cells and cell populations establish the transition of epithelial cells within islets to mesenchymal cells in culture and then to insulin-expressing epithelial cells.