Population viability and harvest sustainability for Madagascar lemurs

Subsistence hunting presents a conservation challenge by which biodiversity preservation must be balanced with safeguarding of human livelihoods. Globally, subsistence hunting threatens primate populations, including Madagascar's endemic lemurs. We used population viability analysis to assess the sustainability of lemur hunting in Makira Natural Park, Madagascar. We identified trends in seasonal hunting of 11 Makira lemur species from household interview data, estimated local lemur densities in populations adjacent to focal villages via transect surveys, and quantified extinction vulnerability for these populations based on species-specific demographic parameters and empirically derived hunting rates. We compared stage-based Lefkovitch with periodic Leslie matrices to evaluate the impact of regional dispersal on persistence trajectories and explored the consequences of perturbations to the timing of peak hunting relative to the lemur birth pulse, under assumptions of density-dependent reproductive compensation. Lemur hunting peaked during the fruit-abundant wet season (March–June). Estimated local lemur densities were roughly inverse to body size across our study area. Life-history modeling indicated that hunting most severely threatened the species with the largest bodies (i.e., Hapalemur occidentalis, Avahi laniger, Daubentonia madagascariensis, and Indri indi), characterized by late-age reproductive onsets and long interbirth intervals. In model simulations, lemur dispersal within a regional metapopulation buffered extinction threats when a majority of local sites supported growth rates above the replacement level but drove regional extirpations when most local sites were overharvested. Hunt simulations were most detrimental when timed to overlap lemur births (a reality for D. madagascariensis and I. indri). In sum, Makira lemurs were overharvested. Regional extirpations, which may contribute to broad-scale extinctions, will be likely if current hunting rates persist. Cessation of anthropogenic lemur harvest is a conservation priority, and development programs are needed to help communities switch from wildlife consumption to domestic protein alternatives.     

Investigating the link between $$\hbox {PM}_{2.5}$$ and atmospheric profile variables via penalized functional quantile regression

Fine particulate matter (\(\hbox {PM}_{2.5}\)) events negatively affect the health of numerous persons globally each year. Previous works have described the association between air pollution and surface-level meteorological conditions; however, there has been less focus on the task of linking air pollution events with meteorological conditions at higher levels of the atmosphere. Working within the functional data framework, we develop a penalized functional quantile regression (PFQR) procedure to model conditional quantiles of a continuous response based on a functional covariate, with the ability to penalize selected derivatives of the estimated coefficient function. Our aim is to investigate the relationship between atmospheric profile variables (APVs), assumed to be functional, and key quantiles of the conditional distribution of surface-level \(\hbox {PM}_{2.5}\). Via a simulation study, we find that the performance of our PFQR procedure compares favorably to other related approaches. We conclude with an analysis of \(\hbox {PM}_{2.5}\) data at two Southeastern US locations, Columbia, SC and Tampa, FL, where we estimate the coefficient functions for the APVs corresponding to both ‘typical’ and ‘high’ \(\hbox {PM}_{2.5}\) events. As we believe that the true coefficient functions are smooth and may be exactly zero over subsets of their domains, we impose penalties on the 0th and 2nd derivatives. Our analysis indicates that the corresponding atmospheric conditions differ between the two locations, and that the conditions differ seasonally within location.     

A land use regression model for predicting ambient volatile organic compound concentrations in Toronto,Canada

More than 25 studies have employed land use regression (LUR) models to estimate nitrogen oxides and to a lesser extent particulate matter indicators, but these methods have been less commonly applied to ambient concentrations of volatile organic compounds (VOCs). Some VOCs have high plausibility as sources of health effects and others are specific indicators of motor vehicle exhaust. We used LUR models to estimate spatial variability of VOCs in Toronto, Canada. Benzene, n-hexane and total hydrocarbons (THC) were measured from July 25 to August 9, 2006 at 50 locations using the TraceAir organic vapor monitors. Nitrogen dioxide (NO₂) was also sampled to assess its spatial pattern agreement with VOC exposures. Buffers for land use, population density, traffic density, physical geography, and remote sensing measures of greenness and surface brightness were also tested. The remote sensing measures have the highest correlations with VOCs and NO₂ levels (i.e., explains >36% of the variance). Our regression models explain 66–68% of the variance in the spatial distribution of VOCs, compared to 81% for the NO₂ model. The ranks of agreement between various VOCs range from 48 to 63% and increases substantially – up to 75% – for the top and bottom quartile groups. Agreements between NO₂ and VOCs are much smaller with an average rank of 36%. Future epidemiologic studies may therefore benefit from using VOCs as potential toxic agents for traffic-related pollutants.     

Contribution of Nitrate and Carbonaceous Species to PM2.5 Observed in Canadian Cities

ABSTRACT

At a variety of Canadian monitoring sites, carbonaceous compounds were estimated to account for an average of 50% of fine particle mass. These estimates were determined by subtracting the total fine particle mass associated with inorganic compounds from the total fine mass determined gravimetrically. This approach, which yields an upper limit estimate of the total amount of carbon-related mass was necessary since particulate carbon was not measured in the Canadian National Air Pollution Surveillance (NAPS) network. In this paper, total carbon estimates are evaluated against organic and elemental carbon measurements at locations in the Greater Vancouver area and Toronto. In addition, particle nitrate measurements at seven Canadian locations are used to determine the importance of nitrate relative to total mass and to examine the sampling artifacts due to the loss of particle nitrate from Teflon filters used in the NAPS di-chotomous samplers.

Measurements of organic and elemental carbon indicated that the total carbon estimation approach provides representative estimates of the average contribution by carbonaceous material to the total fine and coarse mass. The average total carbon among all Vancouver area measurements (N = 225) was 4.28 μg m^-3, while the estimated value was 4.34 μg m^-3. There was a larger discrepancy between Toronto total carbon measurements (12.1 μg m^-3) and estimates (8.8 μg m^-3), which is attributed in part to sampling of particles above 10 mm in diameter. However, the R² relating the measurements and estimates was about 0.71 for both areas. Linear regression slopes of 0.98 for Vancouver and 0.78 for Toronto (nonsignificant intercepts) indicate little bias in the Vancouver estimates, but a tendency for underestimation as the observed total carbon concentration increased in Toronto.

Annually, nitrate was responsible for 17% and 12% of the fine mass in the Vancouver area and Ontario, respectively. In contrast, at two rural locations in southern Quebec and Nova Scotia, only 6% of fine mass was associated with nitrate. Due to filter losses, nitrate concentrations determined through the NAPS dichot sampling were much lower than actual concentrations (0.44 μg m^-3 vs. 2.63 μg m^-3). As a result of these losses (attributed mostly to loss during laboratory storage), previous total carbon estimates for the Canadian NAPS sites were likely to have been overestimated on average by about 10%.     

Description and evaluation of a model of deposition velocities for routine estimates of dry deposition over North America. Part II: review of past measurements and model results

Numerical sensitivity tests and four months of complete model runs have been conducted for the Routine Deposition Model (RDM). The influence of individual model inputs on dry deposition velocity as a function of land-use category (LUC) and pollutant (SO₂, O₃, SO²⁻₄ and HNO₃) were examined over a realistic range of values for solar radiation, stability and wind speed. Spatial and temporal variations in RDM deposition velocity (V_d) during June – September 1996 time period generated using meteorological input from a mesoscale model run at 35 km resolution over north-eastern North America were also examined. Comparison of RDM V_d values to a variety of measurements of dry deposition velocities of SO₂, O₃, SO²⁻₄ and NHO₃ that have been reported in the literature demonstrated that RDM produces realistic results. Over northeastern NA RDM monthly averaged dry deposition velocities for SO₂ vary from 0.2 to 3.0 cm s⁻¹ with the highest deposition velocities over water surfaces. For O₃, the monthly averaged dry deposition velocities are from 0.05 to 1.0 cm s⁻¹ with the lowest values over water surfaces and the highest over forested areas. For HNO₃, the monthly averaged dry deposition velocities have the range of 0.5 to 6 cm s⁻¹, with the highest values for forested areas. For SO²⁻₄, they range from 0.05–1.5 cm s⁻¹, with the lowest values over water and the highest over forest. The monthly averaged dry deposition velocities for SO₂ and O₃ are higher in the growing season compared to the fall, but this behaviour is not apparent for HNO₃ and sulphate. In the daytime, the hourly averaged dry deposition velocities for SO₂, O₃, SO²⁻₄ and HNO₃ are higher than that in the nighttime over most of the vegetated area. The diurnal variation is most evident for surfaces with large values for leaf area index (LAI), such as forests. Based on the results presented in this paper, it is concluded that RDM V_d values can be combined with measured air concentrations over hourly, daily or weekly periods to determine dry deposition amounts and with wet deposition measurements to provide seasonal estimates of total deposition and estimates of the relative importance of dry deposition.     

Characterisation of particulate exposure during fireworks displays

Little is known about the level and content of exposure to fine particles (PM_2.5) among persons who attend fireworks displays and those who live nearby. An evaluation of the levels of PM_2.5 and their elemental content was carried out during the nine launches of the 2007 Montréal International Fireworks Competition. For each event, a prediction of the location of the firework plume was obtained from the Canadian Meteorological Centre (CMC) of the Meteorological Service of Canada. PM_2.5 was measured continuously with a photometer (Sidepak?, TSI) within the predicted plume location (“predicted sites”), and integrated samples were collected using portable personal samplers. An additional sampler was located on a nearby roof (“fixed site”). The elemental composition of the collected PM_2.5 samples from the “predicted sites” was determined using both a non-destructive energy dispersive ED-XRF method and an ICP-MS method with a near-total microwave-assisted acid digestion. The elemental composition of the “fixed site” samples was determined by the ICP-MS with the near-total digestion method. The highest PM_2.5 levels reached nearly 10 000 μg m^?3, roughly 1000 times background levels. Elements such as K, Cl, Al, Mg and Ti were markedly higher in plume-exposed filters. This study shows that 1) persons in the plume and in close proximity to the launch site may be exposed to extremely high levels of PM_2.5 for the duration of the display and, 2) that the plume contains specific elements for which little is known of their acute cardio-respiratory toxicity.     

Monitoring Contrasting Land Management in the Savanna Landscapes of Northern Australia

We compared measures of ecosystem state across six adjacent land-tenure groups in the intact tropical savanna landscapes of northern Australia. Tenure groups include two managed by Aboriginal owners, two national parks, a cluster of pastoral leases, and a military training area. This information is of relevance to the debate about the role of indigenous lands in the Australian conservation estate. The timing and frequency of fire was determined by satellite imagery; the biomass and composition of the herb-layer and the abundance of large feral herbivores by field surveys; and weediness by analysis of a Herbarium database. European tenures varied greatly in fire frequencies but were consistently burnt earlier in the dry season than the two Aboriginal tenures, the latter having intermediate fire frequencies. Weeds were more frequent in the European tenures, whilst feral animals were most abundant in the Aboriginal tenures. This variation strongly implies a signature of current management and/or recent environmental history. We identify indices suitable for monitoring of management outcomes in an extensive and sparsely populated landscape. Aboriginal land offers a unique opportunity for the conservation of biodiversity through the maintenance of traditional fire regimes. However, without financial support, traditional practices may prove unsustainable both economically and because exotic weeds and feral animals will alter fire regimes. An additional return on investment in Aboriginal land management is likely to be improved livelihoods and health outcomes for these disadvantaged communities.     

Decoupling of component and ensemble density feedbacks in birds and mammals

A component density feedback represents the effect of change in population size on single demographic rates, whereas an ensemble density feedback captures that effect on the overall growth rate of a population. Given that a population's growth rate is a synthesis of the interplay of all demographic rates operating in a population, we test the hypothesis that the strength of ensemble density feedback must augment with increasing strength of component density feedback, using long-term censuses of population size, fertility, and survival rates of 109 bird and mammal populations (97 species). We found that compensatory and depensatory component feedbacks were common (each detected in approximately 50% of the demographic rates). However, component feedback strength only explained <10% of the variation in ensemble feedback strength. To explain why, we illustrate the different sources of decoupling between component and ensemble feedbacks. We argue that the management of anthropogenic impacts on populations using component feedbacks alone is ill-advised, just as managing on the basis of ensemble feedbacks without a mechanistic understanding of the contributions made by its components and environmental variability can lead to suboptimal decisions.