Effects of Subsistence Hunting on Vertebrate Community Structure in Amazonian Forests

Abstract: Subsistence hunting affects vast tracts of tropical wilderness that otherwise remain structurally unaltered, yet distinguishing hunted from nonhunted tropical forests presents a difficult problem because this diffuse form of resource extraction leaves few visible signs of its occurrence. I used a standardized series of line-transect censuses conducted over a 10-year period to examine the effects of subsistence game harvest on the structure of vertebrate communities in 25 Amazonian forest sites subjected to varying levels of hunting pressure. Crude vertebrate biomass, which was highly correlated with hunting pressure, gradually declined from nearly 1200 kg km⁻² at nonhunted sites to less than 200 kg km⁻² at heavily hunted sites. Hunting had a negative effect on the total biomass and relative abundance of vertebrate species in different size classes at these forest sites, but it did not affect their overall density. In particular, persistent hunting markedly reduced the density of large-bodied game species (>5 kg), which contributed a large proportion of the overall community biomass at nonhunted sites (65–78%) and lightly hunted sites (55–71%). Nutrient-rich floodplain forests contained a consistently greater game biomass than nutrient-poor unflooded forests, once I controlled for the effects of hunting pressure. Conservative estimates of game yields indicate that as many as 23.5 million game vertebrates, equivalent to 89,224 tons of bushmeat with a market value of US$190.7 million, are consumed each year by the rural population of Brazilian Amazonia, which illustrates the enormous socioeconomic value of game resources in the region. My cross-site comparison documents the staggering effect of subsistence hunters on tropical forest vertebrate communities and highlights the importance of considering forest types and forest productivity in game management programs.     

Choice of Species-Area Function Affects Identification of Hotspots

Abstract: I tested the reliability of species-area curves for use in identifying hotspots, political or geographical regions of high species richness. On a species-area plot, hotspots are points (regions) that appear above the curve to a greater extent than other points. Because several different curves can be fit to species-area data, identification of hotspots may differ depending on the curve-fitting function used. I tested this hypothesis by comparing hotspots identified by the power function, the extreme value function, a linear function, and the exponential function. I examined several species-area data sets varying in size and in the presence of endemics. I defined hotspots as the highest 25% for small data sets and highest 10% and 25% for large data sets of standardized residuals from each function fitted to each data set. For some data sets, the functions agreed in identification of hotspots in that they identified 75% or more of the same hotspots. The extreme value function tended to identify hotspots not identified by the other three functions. For most data sets, the functions did not agree completely in identifying hotspots. Therefore, species-area curves should not be used as the sole means of identifying hotspots of species richness, although they can be used to examine the effect hotspot area has on richness for hotspots identified by other methods.     

The effect of low emission zones on air pollution and infant health

This paper investigates the effect of low emission zones on air quality and birth outcomes in Germany. The staggered introduction of the policy measure creates a credible natural experiment and a natural control group for births and air pollution measurements in cities that enact low emission zones. I show that the introduction of the most restrictive type of low emission zone decreases average levels of fine particulate matter by about 4 percent and by up to 8 percent at a city's highest-polluting monitor. Low emission zones also reduce the number of days per year on which legal pollution limits are exceeded by three. However, these reductions are too small to translate into substantial improvements in infant health. My results are not driven by changes in maternal or city specific characteristics, and are robust to variations in specification and to the choice of control group.     

Common and Conflicting Interests in the Engagements between Conservation Organizations and Corporations

The conservation community increasingly views the corporate sector as a positive force for conservation. Collaborations between corporations and nongovernmental conservation organizations (NGOs) seek to mitigate the negative effects of corporate activities and augment positive conservation outcomes. I reviewed the establishment of corporate social responsibility (CSR) policies by corporations; the emerging focus on environmental practices and sustainability; and the history of engagement between corporations and nongovernmental organizations. I considered the ethical and reputation vulnerabilities of these collaborations, which depend especially on the financial nature of the relationship and reviewed how CSR approaches have influenced corporate practices. I concluded that whereas CSR practices can act to mitigate negative environmental impact, to date they have had limited positive effect on biodiversity conservation. Intereses Comunes y Conflictivos en los Compromisos entre Organizaciones y Corporaciones de Conservación     

Practical Recommendations to Help Students Bridge the Research–Implementation Gap and Promote Conservation

Seasoned conservation researchers often struggle to bridge the research–implementation gap and promote the translation of their work into meaningful conservation actions. Graduate students face the same problems and must contend with obstacles such as limited opportunities for relevant interdisciplinary training and a lack of institutional support for application of research results. However, students also have a crucial set of opportunities (e.g., access to academic resources outside their degree programs and opportunities to design research projects promoting collaboration with stakeholders) at their disposal to address these problems. On the basis of results of breakout discussions at a symposium on the human dimensions of the ocean, a review of the literature, and our own experiences, we devised recommendations on how graduate students can create resources within their academic institutions, institutionalize resources, and engage with stakeholders to promote real‐world conservation outcomes. Within their academic institutions, graduate students should foster links to practitioners and promote knowledge and skill sharing among students. To institutionalize resources, students should cultivate student leaders and faculty sponsors, systematically document their program activities, and engage in strategic planning to promote the sustainability of their efforts. While conducting research, students should create connections to and engage actively with stakeholders in their relevant study areas and disseminate research results both to stakeholders and the broader public. Our recommendations can serve as a template for graduate students wishing to bridge the research–implementation gap, both during their current studies and in their future careers as conservation researchers and practitioners. Recomendaciones Prácticas para Ayudar a Estudiantes a Vencer la Brecha entre Investigación e Implementación y Promover la Conservación     

Spatiotemporal dynamics in variable population interactions with density-dependent interaction coefficients

In this article, I present a two-patch metapopulation model with locally explicit dynamics to study the effect of spatial heterogeneity and dispersal upon population interactions with variable or conditional outcomes. These are interactions that may be either detrimental or beneficial for each species depending on the balance of the density-dependent costs and benefits involved. The local dynamics respond to density-dependent α-interaction functions that may change sign, thus yielding a diversity of possible local outcomes for the association in terms of type of interaction and in the number of stable solutions. The spatiotemporal model predicts that the fragmentation of space and dispersal between patches may cause further variation in these outcomes. First, the demographic performance of a species in the association is enhanced if migrations cause a proportional increase of individuals of its own species; being so, a victim may become a mutualist or an exploiter, an excluded species may invade, and a good competitor may overcome its own carrying capacity: the ‘enhancement effect of dispersal’; a sort of rescue effect in source-sink dynamics. The underlying mechanisms involve an interplay between density-dependent effects of dispersal per se and the relative local and global average α-interaction functions, which involve costs and benefits at both the local and regional level that may either counteract or reinforce each other; thus, localities and/or populations may change dynamically their sink or source role in the spatial dynamics. A significant insight arises herewith: in the context of variable or conditional interactions the concept of the role of a species does not make strict sense; it becomes a spatiotemporal dynamic quality. Second, regardless of which species disperses, bifurcation of equilibria may occur in those patches that receive the migrating individuals, and annihilation of equilibria in those from where migration leaves; thus, the number of equilibria increases or decreases accordingly.     

Translating land-use science to a museum exhibit

For land-use science to engage the general public it must successfully translate its concepts and conclusions and make them public outside of traditional scientific venues. Here we explore science-art exhibits, which blend artistic presentations with specific scientific data or themes, as a possible effective way of communicating scientific information and disrupting misconceptions. We describe the process of producing a science-art exhibit on remote sensing and Puerto Rican landscape history from 1937 to the present, sited at a rural Puerto Rican community museum, and examine the visitor experience and educational outcomes of the museum exhibit through analysis of survey data. The exhibit project engaged undergraduate students from a variety of academic backgrounds, introduced land-use science concepts to the public in an engaging format, and was effective at reshaping visitors’ misconceptions of Puerto Rico’s landscape change history.     

The social cost of carbon revisited

An estimate of the social cost of carbon (SCC) is crucial to climate policy. But how should we estimate the SCC? A common approach uses an integrated assessment model (IAM) to simulate time paths for the atmospheric CO₂ concentration, its impact on temperature, and resulting reductions in GDP. I have argued that IAMs have deficiencies that make them poorly suited for this job, but what is the alternative? I present an approach to estimating an average SCC, which I argue can be a useful guide for policy. I rely on a survey of experts to elicit opinions regarding (1) probabilities of alternative economic outcomes of climate change, but not the causes of those outcomes; and (2) the reduction in emissions required to avert an extreme outcome, i.e., a large climate-induced reduction in GDP. The average SCC is the ratio of the present value of lost GDP from an extreme outcome to the total emission reduction needed to avert that outcome. I discuss the survey instrument, explain how experts were identified, and present results. I obtain SCC estimates of $200/mt or higher, but the variation across experts is large. Trimming outliers and focusing on experts who expressed a high degree of confidence in their answers yields lower SCCs, $80 to $100/mt, but still well above the IAM-based estimates used by the U.S. government.     

Meta-analyses and mega-mistakes: calling time on meta-analysis of the species richness-productivity relationship

The form of the species richness-productivity relationship (SRPR) is both theoretically important and contentious. In an effort to distill general patterns, ecologists have undertaken meta-analyses, within which each SRPR data set is first classified into one of five alternative forms: positive, humped (unimodal), negative, U-shaped (unimodal), and no relationship. Herein, I first provide a critique of this approach, based on 68 plant data sets/ studies used in three meta-analyses published in Ecology. The meta-analyses are shown to have resulted in highly divergent outcomes, inconsistent and often highly inappropriate classification of data sets, and the introduction and multiplication of errors from one meta-analysis to the next. I therefore call on the ecological community at large to adopt a far more rigorous and critical attitude to the use of meta-analysis. Second, I develop the argument that the literature on the SRPR continues to be bedeviled by a common failing to appreciate the fundamental importance of the scale of analysis, beginning with the confusion evident between concepts of grain, focus, and extent. I postulate that variation in the form of the SRPR at fine scales of analysis owes much to artifacts of the sampling regime adopted. An improved understanding may emerge from combining sampling theory with an understanding of the factors controlling the form of species abundance distributions and species accumulation curves.     

Orchestrating Ecosystem Management: Challenges and Lessons from Sequoia National Forest

Abstract: Numerous agencies and organizations have adopted the concept of ecosystem management as a guiding principle in natural resource management. Despite this widespread interest, no single definition of ecosystem management has been accepted, and there are no specific guidelines or standards by which to apply the concept. I examined how one federal agency, the U.S. Forest Service, is applying the principles of ecosystem management at a local level. I present a case study examining management of giant sequoia (   Sequoiadendron giganteum ) in Sequoia National Forest, California, to illuminate the challenges of practicing ecosystem management by associating on-the-ground management activities with ecosystem management themes, characteristics, and mechanisms identified in academic, industry, and agency literature. Experience at Sequoia National Forest suggests that the application of ecosystem management is compromised by poor relations between managers and stakeholders, multifarious policy requirements, budgetary uncertainty, and limited ecological research on which to base management decisions. To facilitate successful application of ecosystem management in the future, I recommend that managers (1) build confidence and trust in the process, (2) acknowledge bias, (3) reconcile policy and funding constraints with long-term planning, (4) invest in scientific research, data collection, and monitoring capacity, and (5) explore the relationship between values and science. These recommendations, although based on the U.S. Forest Service experience, are relevant to natural resource management in general.     

Too hot to handle: The effects of high temperatures during pregnancy on adult welfare outcomes

This paper studies the long-term effects of high temperatures during pregnancy on later-life outcomes for Chinese adults. Adults experienced one additional high-temperature day during in utero period, on average, attain 0.02 fewer years of schooling, increase the risk of illiteracy by 0.18%, achieve lower standardized word-test score by 0.48%, and are shorter by 0.02 cm. The impacts are greater in the first and second trimesters. Additionally, we find that income effects represent one important channel to explain the adverse effects of hot weather. Back-of-the-envelope predictions suggest that by the end of the 21st century, a 0.14–0.54 reduction in years of education and a 0.21–0.84 cm reduction in height is likely to result from climate change, ceteris paribus.     

Indoor air quality in elementary schools of Lisbon in spring

Analysis of indoor air quality (IAQ) in schools usually reveals higher levels of pollutants than in outdoor environments. The aims of this study are to measure indoor and outdoor concentrations of NO₂, speciated volatile organic compounds (VOCs) and carbonyls at 14 elementary schools in Lisbon, Portugal. The investigation was carried out in May–June 2009. Three of the schools were selected to also measure comfort parameters, such as temperature and relative humidity, carbon dioxide (CO₂), carbon monoxide (CO), total VOCs, and bacterial and fungal colony-forming units per cubic metre. Indoor concentrations of CO₂ in the three main schools indicated inadequate classroom air exchange rates. The indoor/outdoor (I/O) NO₂ ratio ranged between 0.36 and 0.95. At the three main schools, the total bacterial and fungal colony-forming units (CFU) in both indoor and outdoor air were above the advised maximum value of 500 CFU/m³ defined by Portuguese legislation. The aromatic compounds benzene, toluene, ethylbenzene and xylenes, followed by ethers, alcohols and terpenes, were usually the most abundant classes of VOCs. In general, the indoor total VOC concentrations were markedly higher than those observed outdoors. At all locations, indoor aldehyde levels were higher than those observed outdoors, particularly for formaldehyde. The inadequate ventilation observed likely favours accumulation of pollutants with additional indoor sources.     

Simulation model of universal law of school size distribution applied to southern bluefin tuna (Thunnus maccoyii) in the Great Australian Bight

A universal law of animal group size distribution correlates well to observed fish school size distribution from fisheries catch data. I applied the law to fisheries independent aerial survey data of southern bluefin tuna (Thunnus maccoyii) collected over a 10-year period in the Great Australian Bight. The law does not correlate to the observed school size distribution. A computer model originally demonstrated the formation of the universal law from simple rules. I redesigned this model as an individual-based simulation model calibrated from acoustic tag observations and state a mathematical formula for a resultant new family of transient group size distributions. The new formula correlates accurately to the simulation and to the aerial survey data. I use the mathematical model to estimate area of aggregation and total abundance. This approach is new as it does not seek stationary states of group size distribution and because it demonstrates a quantitative relationship between individual behaviour and group size distribution. This work elevates the pattern of group size distribution from a curiosity to a useful tool, and introduces a new family of transient distributions that may have a general application to other grouping phenomena.     

The effects of summer heat on academic achievement: A cohort analysis

This paper analyzed the effect of summer heat on academic achievement. Summer heat can negatively affect student learning, as previous studies have shown that high temperatures in laboratory settings have a negative effect on cognitive abilities. For this analysis, the test scores of five different cohorts were combined with city-level daily temperature data. To control for unobserved heterogeneity, the test scores of students within the same school were compared over time (school-fixed effects estimation). Summer heat negatively affected student test scores. Specifically, an additional day with a maximum daily temperature exceeding 34 °C (93.2 °F) during the summer, relative to a day with a maximum temperature between 28 °C (82.4 °F) and 30 °C (86 °F), decreased the scores of math and English tests by 0.0042 and 0.0064 standard deviations, respectively. No significant effects were found on the reading test scores. In addition, these effects were larger in relatively cooler cities, but did not differ based on gender. Finally, the previous year's summer also had negative effects on the current year's test scores.     

Air pollution as a cause of sleeplessness: Social media evidence from a panel of Chinese cities

We provide first evidence of a link from daily air pollution exposure to sleep loss in a panel of Chinese cities. We develop a social media-based, city-level metric for sleeplessness, and bolster causal claims by instrumenting for pollution with plausibly exogenous variations in wind patterns. Estimates of effect sizes are substantial and robust. In our preferred specification a one standard deviation increase in AQI causes an 11.6% increase in sleeplessness, and for PM_2.5 is 12.8%. The results sustain qualitatively under OLS estimation but are attenuated. The analysis provides a previously unaccounted for benefit of more stringent air quality regulation. It also offers a candidate mechanism in support of recent research that links daily air quality to diminished workplace productivity, cognitive performance, school absence, traffic accidents, and other detrimental outcomes.     

Creating local institutional arrangements for sustainable wetland socio-ecological systems: lessons from the ‘Striking a Balance’ project in Malawi

Wetland socio-ecological systems provide livelihood benefits for many poor people throughout the developing world, yet their sustainable development requires local utilisation strategies that balance both environmental and development outcomes. Community-based local institutional arrangements that mediate peoples’ relationships with their environment and facilitate adaptive co-management offer one means of achieving this, and increasingly many NGOs and development practitioners have sought to integrate local institutional capacity building into development projects. In the context of wider academic debates surrounding the long-term sustainability of externally facilitated local institutions, this article draws on the experiences of the three-year Striking a Balance (SAB) project in Malawi which sought to embed sustainable wetland management practices within community-based local institutional arrangements. Drawing on field data collected through participatory methods at three project sites some 5 years after the cessation of project activities, we examine the extent to which SAB’s local institutional capacity building has been successful, and from this draw some lessons for externally driven project interventions which seek win-win outcomes for people and the environment. With reference to Elinor Ostrom’s design principles for long-enduring common property resource institutions, we suggest that the observed declining effectiveness of SAB’s local institutions can be attributed to issues of stakeholder inclusiveness and representations; their sustainability was arguably compromised from their inception on account of them being nested within pre-existing, externally driven village ‘clubs’ whose membership and decision-making was not congruent with all the wetland stakeholders within the community.     

Invading together: the benefits of coalition dispersal in a cooperative bird

Dispersal attempts can be costly and may often end in failure. Individuals should therefore only disperse when the benefits of dispersal outweigh the costs. While previous research has focussed on aspects of the individual that may affect dispersal success, social factors may also influence dispersal outcomes. One way of achieving successful dispersal could be through cooperative, or coalition dispersal. I investigated this possibility in the cooperatively breeding Arabian babbler Turdoides squamiceps. I found that coalition dispersal appears to be an effective strategy to ensure the success of dispersal attempts, with coalitions more successful than lone individuals at taking over the breeding position in a new group. Lone dispersal was more costly than coalition dispersal, with lone individuals suffering a greater loss of body mass during dispersal attempts. These results suggest a substantial short-term benefit for this type of cooperative behaviour. There was no evidence for dispersal polymorphism in the population, with no detectable phenotypic difference between dispersers and non-dispersers or those that dispersed as part of a coalition compared with those that dispersed alone.     

Does mating experience of male house crickets affect their behavior to subsequent females and female choice?

Male mating experience was shown to play an important role in settling conflicts between males; however, little is known about whether and how prior access to females influences male behavior during intersexual interactions and female choice itself. Here, I experimentally test this relationship in the house cricket (Acheta domesticus) by combining one-on-one interaction between the male and female with direct comparison of males by the female, but precluding aggression between males. I found that solitary males were more active during subsequent courtship displays than paired males, suggesting the detrimental effect of mating on courtship performance. At the same time, females spent significantly more time close to solitary males or playbacks of male's natural courtship songs, and responded positively to the condition of males, ignoring body size of males. In contrast, females responded similarly to computer-modified playbacks of courtship songs of solitary and paired males with standardized rate of phrases and amplitudes; however, when females were additionally allowed to contact with anesthetized males they spent more time close to bigger males, irrespective of the acoustic parameters of courtship songs. These results show that although females were able to differentiate between many behavioral and morphological characteristics of males, including voluntary and intrinsic ones, they preferred traits conditional upon the costliness of male's displays. In addition, mating experience appeared to be a crucial factor in the choice of a particular costly mating strategy by males.     

Evidence of variable discount rates and non-standard discounting in mortality risk valuation

Time discounting is central to the valuation of future health and mortality risks in public sector allocative decision-making, particularly for environmental policies with delayed health impacts. Using a Risk-Risk trade-off survey, we elicit discount rates for fatality risks and establish discounting functional forms on both a sample and an individual level. We find wide variation in implicit discount rates for fatality risk between individuals, as well as between-individual heterogeneity in discounting functional forms. In aggregate, the sample is best characterised by subadditive discounting. Our work has implications for the academic investigation of intertemporal choice involving mortality risks, and potentially for the evaluation of policy options with delayed mortality risk outcomes. A thought experiment cautions against the standard practice of assuming that exponential discounting characterises society's time preferences.     

Animal agency in wildlife conservation and management

Wildlife conservation and management (WCM) practices have been historically drawn from a wide variety of academic fields, yet practitioners have been slow to engage with emerging conversations about animals as complex beings, whose individuality and sociality influence their relationships with humans. We propose an explicit acknowledgement of wild, nonhuman animals as active participants in WCM. We examined 190 studies of WCM interventions and outcomes to highlight 3 common assumptions that underpin many present approaches to WCM: animal behaviors are rigid and homogeneous; wildlife exhibit idealized wild behavior and prefer pristine habitats; and human–wildlife relationships are of marginal or secondary importance relative to nonhuman interactions. We found that these management interventions insufficiently considered animal learning, decision-making, individuality, sociality, and relationships with humans and led to unanticipated detrimental outcomes. To address these shortcomings, we synthesized theoretical advances in animal behavioral sciences, animal geographies, and animal legal theory that may help conservation professionals reconceptualize animals and their relationships with humans. Based on advances in these fields, we constructed the concept of animal agency, which we define as the ability of animals to actively influence conservation and management outcomes through their adaptive, context-specific, and complex behaviors that are predicated on their sentience, individuality, lived experiences, cognition, sociality, and cultures in ways that shape and reshape shared human–wildlife cultures, spaces, and histories. Conservation practices, such as compassionate conservation, convivial conservation, and ecological justice, incorporate facets of animal agency. Animal agency can be incorporated in conservation problem-solving by assessing the ways in which agency contributes to species’ survival and by encouraging more adaptive and collaborative decision-making among human and nonhuman stakeholders.