Rain‐washing of foliar deposits of Dimilin®WP‐25 formulated in four different carrier liquids

Abstract

Dimilin^® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray^® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol^® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585.     

Effect of Planning for Connectivity on Linear Reserve Networks

Although the concept of connectivity is decades old, it remains poorly understood and defined, and some argue that habitat quality and area should take precedence in conservation planning instead. However, fragmented landscapes are often characterized by linear features that are inherently connected, such as streams and hedgerows. For these, both representation and connectivity targets may be met with little effect on the cost, area, or quality of the reserve network. We assessed how connectivity approaches affect planning outcomes for linear habitat networks by using the stock‐route network of Australia as a case study. With the objective of representing vegetation communities across the network at a minimal cost, we ran scenarios with a range of representation targets (10%, 30%, 50%, and 70%) and used 3 approaches to account for connectivity (boundary length modifier, Euclidean distance, and landscape‐value [LV]). We found that decisions regarding the target and connectivity approach used affected the spatial allocation of reserve systems. At targets ≥50%, networks designed with the Euclidean distance and LV approaches consisted of a greater number of small reserves. Hence, by maximizing both representation and connectivity, these networks compromised on larger contiguous areas. However, targets this high are rarely used in real‐world conservation planning. Approaches for incorporating connectivity into the planning of linear reserve networks that account for both the spatial arrangement of reserves and the characteristics of the intervening matrix highlight important sections that link the landscape and that may otherwise be overlooked. El Efecto de la Planeación para la Conectividad en Redes de Reservas Lineales     

Temporal Analysis of Genetic Structure to Assess Population Dynamics of Reintroduced Swift Foxes

Reintroductions are increasingly used to reestablish species, but a paucity of long‐term postrelease monitoring has limited understanding of whether and when viable populations subsequently persist. We conducted temporal genetic analyses of reintroduced populations of swift foxes (Vulpes velox) in Canada (Alberta and Saskatchewan) and the United States (Montana). We used samples collected 4 years apart, 17 years from the initiation of the reintroduction, and 3 years after the conclusion of releases. To assess program success, we genotyped 304 hair samples, subsampled from the known range in 2000 and 2001, and 2005 and 2006, at 7 microsatellite loci. We compared diversity, effective population size, and genetic connectivity over time in each population. Diversity remained stable over time and there was evidence of increasing effective population size. We determined population structure in both periods after correcting for differences in sample sizes. The geographic distribution of these populations roughly corresponded with the original release locations, which suggests the release sites had residual effects on the population structure. However, given that both reintroduction sites had similar source populations, habitat fragmentation, due to cropland, may be associated with the population structure we found. Although our results indicate growing, stable populations, future connectivity analyses are warranted to ensure both populations are not subject to negative small‐population effects. Our results demonstrate the importance of multiple sampling years to fully capture population dynamics of reintroduced populations. Análisis Temporal de la Estructura Genética para Evaluar la Dinámica Poblacional de Zorros (Vulpes velox) Reintroducidos     

Mitigating the Effect of Development on Bats in England with Derogation Licensing

The Convention on Biological Diversity has catalyzed worldwide awareness of threats to biological diversity and stimulated global conservation strategies. These have led to national and international legislation and have generated debate about the most effective conservation actions. Under the EU Habitats Directive, all member states are obliged to establish a system for strict protection of species listed in Annex IV(a), which includes all bats. In England, this obligation has resulted in legislation that allows for derogation from strict protection under license, provided activities are undertaken to mitigate any potential negative effects on bat numbers. We used an evidence‐based approach to assess the cost‐effectiveness of mitigation strategies and the English bat‐derogation licensing process as a whole. We analyzed data from 389 bat derogation licenses issued in England from 2003 to 2005 relating to 1776 roosts and 15 species to determine the nature and extent of development and mitigation activities and their effects on bats. Overall the effects of licensed activities on roosts were negative. Despite the level of protection afforded to bats, the majority (68%) of roosts for which derogation licenses were issued were destroyed. There were species‐specific differences in the probability of roosts being destroyed, and impacts on roosts did not reflect a species’ conservation status. Information provided by licensees was inadequate and inconsistent. Most licensees (67%) failed to submit postdevelopment reports, and postdevelopment monitoring was conducted at only 19% of sites. Despite a minimum of £4.13 million spent on mitigation structures for bats from 2003 to 2005, it was unclear whether the licensing process meets EU obligations. On the basis of our results, we believe there is a need to overhaul the licensing process, to establish a comprehensive, standardized postdevelopment monitoring system, and to demonstrate that mitigation is commensurate with Britain's legal obligations. Mitigando el Efecto del Desarrollo sobre los Murciélagos en Inglaterra con Licencias de Derogación     

Fire Mosaics and Reptile Conservation in a Fire‐Prone Region

Fire influences the distribution of fauna in terrestrial biomes throughout the world. Use of fire to achieve a mosaic of vegetation in different stages of succession after burning (i.e., patch‐mosaic burning) is a dominant conservation practice in many regions. Despite this, knowledge of how the spatial attributes of vegetation mosaics created by fire affect fauna is extremely scarce, and it is unclear what kind of mosaic land managers should aim to achieve. We selected 28 landscapes (each 12.6 km²) that varied in the spatial extent and diversity of vegetation succession after fire in a 104,000 km² area in the semiarid region of southeastern Australia. We surveyed for reptiles at 280 sites nested within the 28 landscapes. The landscape‐level occurrence of 9 of the 22 species modeled was associated with the spatial extent of vegetation age classes created by fire. Biogeographic context and the extent of a vegetation type influenced 7 and 4 species, respectively. No species were associated with the diversity of vegetation ages within a landscape. Negative relations between reptile occurrence and both extent of recently burned vegetation (≤10 years postfire, n = 6) and long unburned vegetation (>35 years postfire, n = 4) suggested that a coarse‐grained mosaic of areas (e.g. >1000 ha) of midsuccessional vegetation (11–35 years postfire) may support the fire‐sensitive reptile species we modeled. This age class coincides with a peak in spinifex cover, a keystone structure for reptiles in semiarid and arid Australia. Maintaining over the long term a coarse‐grained mosaic of large areas of midsuccessional vegetation in mallee ecosystems will need to be balanced against the short‐term negative effects of large fires on many reptile species and a documented preference by species from other taxonomic groups, particularly birds, for older vegetation. Mosaicos de Fuego y la Conservación de Reptiles en una Región Propensa al Fuego     

Paradigms for parasite conservation

Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite‐inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid‐20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host‐density threshold and cost‐benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host–parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of an uncertain environmental future.     

Sorption and desorption kinetics of diuron,fluometuron, prometryn and pyrithiobac sodium in soils

Abstract

The sorption and desorption characteristics of four herbicides (diuron, fluometuron, prometryn and pyrithiobac‐sodium) in three different cotton growing soils of Australia was investigated. Kinetics and equilibrium sorption and desorption isotherms were determined using the batch equilibrium technique. Sorption was rapid (> 80% in 2 h) and sorption equilibrium was achieved within a short period of time (ca 4 h) for all herbicides. Sorption isotherms of the four herbicides were described by Freundlich equation with an r² value > 0.98. The herbicide sorption as measured by the distribution coefficient (K_d) values ranged from 3.24 to 5.71 L/kg for diuron, 0.44 to 1.13 L/kg for fluometuron, 1.78 to 6.04 L/kg for prometryn and 0.22 to 0.59 L/kg for pyrithiobac‐sodium. Sorption of herbicides was higher in the Moree soil than in Narrabri and Wee Waa soils. When the K_d values were normalised to organic carbon content of the soils (K_oC), it suggested that the affinity of the herbicides to the organic carbon increased in the order: pyrithiobac‐sodium < fluometuron < prometryn < diuron. The desorption isotherms were also adequately described by the Freundlich equation. For desorption, all herbicides exhibited hysteresis and the hysteresis was stronger for highly sorbed herbicides (diuron and prometryn) than the weakly sorbed herbicides (fluometuron and pyrithiobac‐sodium). Hysteresis was also quantified as the percentage of sorbed herbicides which is not released during the desorption step ω = [n_ad / n_de ‐1] x 100). Soil type and initial concentration had significant effect on ω. The effect of sorption and desorption properties of these four herbicides on the off‐site transport to contaminate surface and groundwater are also discussed in this paper.     

Bayesian Small Area Models for Assessing Wildlife Conservation Risk in Patchy Populations

Abstract:  Species conservation risk assessments require accurate, probabilistic, and biologically meaningful maps of population distribution. In patchy populations, the reasons for discontinuities are not often well understood. We tested a novel approach to habitat modeling in which methods of small area estimation were used within a hierarchical Bayesian framework. Amphibian occurrence was modeled with logistic regression that included third-order drainages as hierarchical effects to account for patchy populations. Models including the random drainage effects adequately represented species occurrences in patchy populations of 4 amphibian species in the Oregon Coast Range (U.S.A.). Amphibian surveys from other locations within the same drainage were used to calibrate local drainage-scale effects. Cross-validation showed that prediction errors for calibrated models were 77% to 86% lower than comparable regionally constructed models, depending on species. When calibration data were unavailable, small area and regional models performed similarly, although poorly. Small area estimation models complement wildlife ecology and habitat studies, and can help managers develop a regional picture of the conservation status for relatively rare species.     

Evaluating the Success of Conservation Actions in Safeguarding Tropical Forest Biodiversity

Abstract: We reviewed the evidence on the extent and efficacy of conservation of tropical forest biodiversity for each of the classes of conservation action defined by the new International Union for Conservation of Nature (IUCN) classification. Protected areas are the most tested conservation approach, and a number of studies show they are generally effective in slowing deforestation. There is some documentation of the extent of sustainable timber management in tropical forest, but little information on other landscape‐conservation tactics. The extent and effectiveness of ex situ species conservation is quite well known. Forty‐one tropical‐forest species now survive only in captivity. Other single‐species conservation actions are not as well documented. The potential of policy mechanisms, such as international conventions and provision of funds, to slow extinctions in tropical forests is considerable, but the effects of policy are difficult to measure. Finally, interventions to promote tropical conservation by supporting education and livelihoods, providing incentives, and furthering capacity building are all thought to be important, but their extent and effectiveness remain poorly known. For birds, the best studied taxon, the sum of such conservation actions has averted one‐fifth of the extinctions that would otherwise have occurred over the last century. Clearly, tropical forest conservation works, but more is needed, as is critical assessment of what works in what circumstances, if mass extinction is to be averted.     

The effects of triclopyr on 2,4‐D mineralization in two soils

Abstract

The effects of the herbicide triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) on the mineralization of 2,4‐D (2,4‐dichlorophenoyxacetic acid) in two soils which differed in their histories of prior exposure to the two herbicides were investigated. The relative effects of triclopyr on 2,4‐D mineralization and most probable numbers of 2,4‐D degraders were dependent upon the soil. Triclopyr was shown to increase 2,4‐D mineralization rates in a soil which had been exposed to both 2,4‐D and triclopyr, but decreased the mineralization rate of 2,4‐D and inhibited the increase of most probable numbers of 2,4‐D degraders in a soil that had not been directly exposed to either herbicide.