Effects of time since fire on birds: how informative are generalized fire response curves for conservation management?

Fire is both a widespread natural disturbance that affects the distribution of species and a tool that can be used to manage habitats for species. Knowledge of temporal changes in the occurrence of species after fire is essential for conservation management in fire-prone environments. Two key issues are: whether postfire responses of species are idiosyncratic or if multiple species show a limited number of similar responses; and whether such responses to time since fire can predict the occurrence of species across broad spatial scales. We examined the response of bird species to time since fire in semiarid shrubland in southeastern Australia using data from surveys at 499 sites representing a 100-year chronosequence. We used nonlinear regression to model the probability of occurrence of 30 species with time since fire in two vegetation types, and compared species' responses with generalized response shapes from the literature. The occurrence of 16 species was significantly influenced by time since fire: they displayed six main responses consistent with generalized response shapes. Of these 16 species, 15 occurred more frequently in mid- or later-successional vegetation (> 20 years since fire), and only one species occurred more often in early succession (< 5 years since fire). The models had reasonable predictive ability for eight species, some predictive ability for seven species, and were little better than random for one species. Bird species displayed a limited range of responses to time since fire; thus a small set of fire ages should allow the provision of habitat for most species. Postfire successional changes extend for decades and management of the age class distribution of vegetation will need to reflect this timescale. Response curves revealed important seral stages for species and highlighted the importance of mid- to late-successional vegetation (> 20 years). Although time since fire clearly influences the distribution of numerous bird species, predictive models of the spatial distribution of species in fire-prone landscapes need to incorporate other factors in addition to time since fire.     

Our disappearing past: a GIS analysis of the vulnerability of coastal archaeological resources in California’s Santa Barbara Channel region

Coastal archaeological resources around the world often coincide with dense contemporary human populations and a rapidly changing physical environment. Projected sea level rise and urban expansion during the 21^st century threaten to destroy much of our global coastal archaeological heritage. In this study, we adapt an environmental vulnerability analysis to quantify the threats of modern development and sea level rise on archaeological sites in California’s Santa Barbara Channel region. Using spatial and statistical techniques, we create a Cultural Resource Vulnerability Index that combines environmental factors, current and projected urban footprints, and archaeological site positioning. We illustrate the importance of this method for targeting threatened archaeological sites for mitigation and salvage research. In the process, we highlight the significance of coastal archaeological sites for helping better understand contemporary environmental and cultural issues, underscoring the need to preserve or salvage these sites for their significant research value.     

Midwest U.S. landscape change to 2020 driven by biofuel mandates

Meeting future biofuel targets set by the 2007 Energy Independence and Security Act (EISA) will require a substantial increase in production of corn. The Midwest, which has the highest overall crop production capacity, is likely to bear the brunt of the biofuel-driven changes. In this paper, we set forth a method for developing a possible future landscape and evaluate changes in practices and production between base year (BY) 2001 and biofuel target (BT) 2020. In our BT 2020 Midwest landscape, a total of 25 million acres (1 acre = 0.40 ha) of farmland was converted from rotational cropping to continuous corn. Several states across the Midwest had watersheds where continuous corn planting increased by more than 50%. The output from the Center for Agriculture and Rural Development (CARD) econometric model predicted that corn grain production would double. In our study we were able to get within 2% of this expected corn production. The greatest increases in corn production were in the Corn Belt as a result of conversion to continuous corn planting. In addition to changes to cropping practices as a result of biofuel initiatives we also found that urban growth would result in a loss of over 7 million acres of productive farmland by 2020. We demonstrate a method which successfully combines economic model output with gridded land cover data to create a spatially explicit detailed classification of the landscape across the Midwest. Understanding where changes are likely to take place on the landscape will enable the evaluation of trade-offs between economic benefits and ecosystem services allowing proactive conservation and sustainable production for human well-being into the future.     

Wildlife collection for scientific purposes

Illegal transfer of wildlife has 2 main purposes: trade and scientific research. Trade is the most common, whereas scientific research is much less common and unprofitable, yet still important. Biopiracy in science is often neglected despite that many researchers encounter it during their careers. The use of illegally acquired specimens is detected in different research fields, from scientists bioprospecting for new pharmacological substances, to taxonomists working on natural history collections, to researchers working in zoos, aquariums, and botanical gardens. The practice can be due to a lack of knowledge about the permit requirements in different countries or, probably most often, to the generally high level of bureaucracy associated with rule compliance. Significant regulatory filters to avoid biopiracy can be provided by different stakeholders. Natural history collection hosts should adopt strict codes of conduct; editors of scientific publications should require authors to declare that all studied specimens were acquired legally and to cite museum catalog numbers as guarantee of best practices. Scientific societies should actively encourage publication in peer-reviewed journals of work in which specimens collected from the wild were used. The International Commission on Zoological Nomenclature could require newly designated types based on recently collected specimens to be accompanied by statements of deposition in recognized scientific or educational institutions. We also propose the creation of an online platform that gathers information about environmental regulations and permits required for scientific activities in different countries and respective responsible governmental agencies and the simplification of the bureaucracy related to regulating scientific activities. This would make regulations more agile and easier to comply with. The global biodiversity crisis means data need to be collected ever faster, but biopiracy is not the answer and undermines the credibility of science and researchers. It is critical to find a modus vivendi that promotes compliance with regulations and scientific progress.     

DISTRIBUTED RUNOFF FORMULATION DESIGNED FOR A PRECISION AGRICULTURAL LANDSCAPE MODELING SYSTEM1

A precision scale landscape model designed for agricultural applications is described in this paper. The Precision Agricultural Landscape Modeling System (PALMS) is a combination of two process‐based models: a diffusive wave runoff model with ponding (described in detail) and a biosphere model with a crops module (briefly reviewed). Several innovations, including numerical formulations for the hydrologic properties of the soil surface with crusting, slope/tillage angle interactions, and change of roughness and detention storage with cumulative precipitation have been included. The model is compared to observations on one 1.8 ha field planted with maize and soybeans during four growing seasons, and one 24 ha field planted with maize during one growing season. Daily average soil moisture is simulated well (within 5 percent volumetric), except in extended runoff/ponding episodes. Physical processes not simulated in the model suggest possible explanations for model errors. Planned improvements for PALMS are also presented.     

Silica reduces the toxicity of aluminium to a tropical freshwater fish (Mogurnda mogurnda)

The toxicity of aluminium (Al) to fish in acidic waters has been well documented. It was therefore expected that Al toxicity would be significant in fish communities in Gadjarrigamarndah (Gadji) Creek, a seasonally flowing stream in tropical northern Australia. This creek receives acidic groundwater containing elevated concentrations of Al from earlier land irrigation of treated mine tailings water from the former Nabarlek uranium mine. It was hypothesised that Al toxicity was reduced by high levels of silica (Si) in the water, and the subsequent formation of Al-silicate complexes. This prompted a laboratory assessment of the toxicity of Gadji Creek water to sac-fry of the native fish, Mogurnda mogurnda, followed by more detailed investigation of the toxicity of Al and the influence of Si in reducing Al toxicity. No mortality of M. mogurnda sac-fry was observed in two toxicity tests using Gadji Creek water collected in August 1997 and September 1998. The majority of Al (80-95%) was calculated to be complexed with humic substances and sulfate, with < 1% being complexed with silicate. Assessment of the influence of silica on the acute toxicity of Al in the absence of natural organic complexants (i.e. in reconstituted freshwater, pH 5) revealed that Si reduced Al toxicity. As the molar ratio of Si:Al was increased, the percent survival of M. mogurnda sac-fry increased until there was no significant (P > 0.05) difference from the controls. However, speciation modelling again predicted that little (< 3%) Al complexed with silicate, with the speciation and bioavailability of Al remaining constant as the molar ratio of Si:Al increased. Therefore, the original hypothesis that Al-silicate complexes in solution reduced the toxicity of Al to M. mogurnda could not be supported. This potential mechanism, and an alternative hypothesis, that Si competes with Al for binding sites at the fish gill surface, requires further investigation.     

How flexible is phenotypic plasticity? Developmental windows for trait induction and reversal

Inducible defenses allow prey to modulate their phenotypic responses to the level of predation risk in the environment and reduce the cost of constitutive defenses. Inherent in this statement is that prey must alter their phenotypes during development in order to form these defenses. This has lead many ecologists and evolutionary biologists to call for studies that examine developmental plasticity to provide insights into the importance of development in controlling the trajectories of trait formation, the integration of phenotypes over ontogeny, and the establishment of developmental windows for trait formation and reversal. By moving away from studies that focus on a single point in development, we can obtain a more complete understanding of the phenotypic decisions and limitations of prey. We exposed freshwater snails (Helisoma trivolvis) to environments in which predatory water bugs (Belostoma flumineum) were always absent, always present, or added and removed at different points in development. We discovered that snails formed morphological defenses against water bugs. Importantly, after the initial induction of defenses, snails showed similar developmental trajectories as snails reared without predators. Further, the snails possessed wide developmental windows for inducible defenses that extended past sexual maturity. However, being induced later in development appeared to have an associated cost (i.e., decreased shell thickness) that was not found when water bugs were always present. This epiphenotype (i.e., new shell formation as an extension of the current shell) suggests that resource limitation plays an important role in responses to temporal variation in predation risk and may have critical ecological costs that limit the benefits of the inducible defense. Lastly, the ability of snails to completely reverse their defenses was limited to early in ontogeny due to the constraints associated with modular growth of shell material. In sum, we demonstrate that taking a developmental perspective is extremely valuable for understanding the ecology of inducible defenses.