The role of protected areas in maintaining natural vegetation in Brazil.

The destruction of natural vegetation in recent decades has been concentrated in the tropics, where ecosystem processes underpin global homeostasis and harbor most of the world's biodiversity. Protected areas (PAs) are the primary societal tool to avoid this destruction, yet their effectiveness is often questioned. Here, we quantified the impact of PAs and indigenous lands in avoiding 34 years of vegetation destruction in forested and nonforested biomes in Brazil. We showed that the odds of destruction in the PA network are four times lower than in unprotected areas, and generally, this positive effect extends to a buffer zone around PAs. Among the most effective groups of PAs are those that are older, larger, located in the Amazonian region, and indigenous lands. Despite recent setbacks for the Brazilian PA system, we highlight the benefits of PAs for biodiversity and climate if they were instead strengthened.

When are hypotheses useful in ecology and evolution?

Research hypotheses have been a cornerstone of science since before Galileo. Many have argued that hypotheses (1) encourage discovery of mechanisms, and (2) reduce bias-both features that should increase transferability and reproducibility. However, we are entering a new era of big data and highly predictive models where some argue the hypothesis is outmoded. We hypothesized that hypothesis use has declined in ecology and evolution since the 1990s, given the substantial advancement of tools further facilitating descriptive, correlative research. Alternatively, hypothesis use may have become more frequent due to the strong recommendation by some journals and funding agencies that submissions have hypothesis statements. Using a detailed literature analysis (N = 268 articles), we found prevalence of hypotheses in eco-evo research is very low (6.7%-26%) and static from 1990-2015, a pattern mirrored in an extensive literature search (N = 302,558 articles). Our literature review also indicates that neither grant success nor citation rates were related to the inclusion of hypotheses, which may provide disincentive for hypothesis formulation. Here, we review common justifications for avoiding hypotheses and present new arguments based on benefits to the individual researcher. We argue that stating multiple alternative hypotheses increases research clarity and precision, and is more likely to address the mechanisms for observed patterns in nature. Although hypotheses are not always necessary, we expect their continued and increased use will help our fields move toward greater understanding, reproducibility, prediction, and effective conservation of nature.

The environmental costs and benefits of high-yield farming.

How we manage farming and food systems to meet rising demand is pivotal to the future of biodiversity. Extensive field data suggest impacts on wild populations would be greatly reduced through boosting yields on existing farmland so as to spare remaining natural habitats. High-yield farming raises other concerns because expressed per unit area it can generate high levels of externalities such as greenhouse gas (GHG) emissions and nutrient losses. However, such metrics underestimate the overall impacts of lower-yield systems, so here we develop a framework that instead compares externality and land costs per unit production. Applying this to diverse datasets describing the externalities of four major farm sectors reveals that, rather than involving trade-offs, the externality and land costs of alternative production systems can co-vary positively: per unit production, land-efficient systems often produce lower externalities. For GHG emissions these associations become more strongly positive once forgone sequestration is included. Our conclusions are limited: remarkably few studies report externalities alongside yields; many important externalities and farming systems are inadequately measured; and realising the environmental benefits of high-yield systems typically requires additional measures to limit farmland expansion. Yet our results nevertheless suggest that trade-offs among key cost metrics are not as ubiquitous as sometimes perceived.

Carbon Storage and Land-Use Strategies in Agricultural Landscapes across Three Continents.

The loss of carbon stocks through agricultural land-use change is a key driver of greenhouse gas emissions [1-4], and the methods used to manage agricultural land will have major impacts on the global climate in the 21st century [4-9]. It remains unresolved whether carbon losses would be minimized by increasing farm yields and limiting the conversion of natural habitats ("land sparing"), or maximizing on-farm carbon stocks, even at the cost of reduced yields and therefore greater habitat clearance ("land sharing"). In this paper, we use field surveys of over 11,000 trees, in-depth interviews with farmers, and existing agricultural data, to evaluate the potential impacts of these contrasting approaches, and plausible intermediate strategies, on above-ground carbon stocks across a diverse range of agricultural and natural systems. Our analyses include agroforestry and oil palm plantations in the humid tropics of Ghana; cattle ranching in dry tropical forest in Mexico; and arable cropping in temperate wetlands and forests in Poland. Strikingly, despite the range of systems investigated, land sparing consistently had a higher potential to sustain regional above-ground carbon stocks than any other strategy. This was the case in all three regions and at all plausible levels of food production, including falls in demand. However, if agricultural production increases to meet likely future demand levels, we project large decreases in above-ground carbon stocks, regardless of land-use strategy. Our results strongly suggest that maintaining above-ground carbon stocks will depend on both limiting future food demand and minimizing agricultural expansion through linking high-yield farming with conserving or restoring natural habitats.

Global forest loss disproportionately erodes biodiversity in intact landscapes.

Global biodiversity loss is a critical environmental crisis, yet the lack of spatial data on biodiversity threats has hindered conservation strategies. Theory predicts that abrupt biodiversity declines are most likely to occur when habitat availability is reduced to very low levels in the landscape (10-30%). Alternatively, recent evidence indicates that biodiversity is best conserved by minimizing human intrusion into intact and relatively unfragmented landscapes. Here we use recently available forest loss data to test deforestation effects on International Union for Conservation of Nature Red List categories of extinction risk for 19,432 vertebrate species worldwide. As expected, deforestation substantially increased the odds of a species being listed as threatened, undergoing recent upgrading to a higher threat category and exhibiting declining populations. More importantly, we show that these risks were disproportionately high in relatively intact landscapes; even minimal deforestation has had severe consequences for vertebrate biodiversity. We found little support for the alternative hypothesis that forest loss is most detrimental in already fragmented landscapes. Spatial analysis revealed high-risk hot spots in Borneo, the central Amazon and the Congo Basin. In these regions, our model predicts that 121-219 species will become threatened under current rates of forest loss over the next 30 years. Given that only 17.9% of these high-risk areas are formally protected and only 8.9% have strict protection, new large-scale conservation efforts to protect intact forests are necessary to slow deforestation rates and to avert a new wave of global extinctions.

Land-use strategies to balance livestock production, biodiversity conservation and carbon storage in Yucatán, Mexico.

Balancing the production of food, particularly meat, with preserving biodiversity and maintaining ecosystem services is a major societal challenge. Research into the contrasting strategies of land sparing and land sharing has suggested that land sparing-combining high-yield agriculture with the protection or restoration of natural habitats on nonfarmed land-will have lower environmental impacts than other strategies. Ecosystems with long histories of habitat disturbance, however, could be resilient to low-yield agriculture and thus fare better under land sharing. Using a wider suite of species (birds, dung beetles and trees) and a wider range of livestock-production systems than previous studies, we investigated the probable impacts of different land-use strategies on biodiversity and aboveground carbon stocks in the Yucatán Peninsula, Mexico-a region with a long history of habitat disturbance. By modelling the production of multiple products from interdependent land uses, we found that land sparing would allow larger estimated populations of most species and larger carbon stocks to persist than would land sharing or any intermediate strategy. This result held across all agricultural production targets despite the history of disturbance and despite species richness in low- and medium-yielding agriculture being not much lower than that in natural habitats. This highlights the importance, in evaluating the biodiversity impacts of land use, of measuring population densities of individual species, rather than simple species richness. The benefits of land sparing for both biodiversity and carbon storage suggest that safeguarding natural habitats for biodiversity protection and carbon storage alongside promoting areas of high-yield cattle production would be desirable. However, delivering such landscapes will probably require the explicit linkage of livestock yield increases with habitat protection or restoration, as well as a deeper understanding of the long-term sustainability of yields, and research into how other societal outcomes vary across land-use strategies.

Getting Road Expansion on the Right Track: A Framework for Smart Infrastructure Planning in the Mekong.

The current unprecedented expansion of infrastructure promises to enhance human wellbeing but risks causing substantial harm to natural ecosystems and the benefits they provide for people. A framework for systematically and proactively identifying the likely benefits and costs of such developments is badly needed. Here, we develop and test at the subregional scale a recently proposed global scheme for comparing the potential gains from new roads for food production with their likely impact on biodiversity and ecosystem services. Working in the Greater Mekong-an exceptionally biodiverse subregion undergoing rapid development-we combined maps of isolation from urban centres, yield gaps, and the current area under 17 crops to estimate where and how far road development could in principle help to increase food production without the need for cropland expansion. We overlaid this information with maps summarising the importance of remaining habitats to terrestrial vertebrates and (as examples of major ecosystem services) to global and local climate regulation. This intersection revealed several largely converted yet relatively low-yielding areas (such as central, eastern, and northeastern Thailand and the Ayeyarwady Delta), where narrowing yield gaps by improving transport links has the potential to substantially increase food production at relatively limited environmental cost. Concentrating new roads and road improvements here while taking strong measures to prevent their spread into areas which are still extensively forested (such as northern Laos, western Yunnan, and southwestern Cambodia) could thus enhance rural livelihoods and regional food production while helping safeguard vital ecosystem services and globally significant biological diversity.

Reducing the land use of EU pork production: where there's swill, there's a way.

Livestock production occupies approximately 75% of agricultural land, consumes 35% of the world's grain, and produces 14.5% of anthropogenic greenhouse gas emissions. With demand for meat and dairy products forecast to increase 60% by 2050, there is a pressing need to reduce the footprint of livestock farming. Food wastes have a long history as a source of environmentally benign animal feed, but their inclusion in feed is currently banned in the EU because of disease control concerns. A number of East Asian states have in the last 20 years, however, introduced regulated, centralised systems for safely recycling food wastes into animal feed. This study quantifies the land use savings that could be realised by changing EU legislation to promote the use of food wastes as animal feed and reviews the policy, public, and industry barriers to the use of food waste as feed. Our results suggest that the application of existing technologies could reduce the land use of EU pork (20% of world production) by one fifth, potentially saving 1.8 million hectares of agricultural land. While swill presents a low-cost, low-impact animal feed, widespread adoption would require efforts to address consumer and farmer concerns over food safety and disease control.

Age-related variation in foraging behaviour in the wandering albatross at South Georgia: no evidence for senescence.

Age-related variation in demographic rates is now widely documented in wild vertebrate systems, and has significant consequences for population and evolutionary dynamics. However, the mechanisms underpinning such variation, particularly in later life, are less well understood. Foraging efficiency is a key determinant of fitness, with implications for individual life history trade-offs. A variety of faculties known to decline in old age, such as muscular function and visual acuity, are likely to influence foraging performance. We examine age-related variation in the foraging behaviour of a long-lived, wide-ranging oceanic seabird, the wandering albatross Diomedea exulans. Using miniaturised tracking technologies, we compared foraging trip characteristics of birds breeding at Bird Island, South Georgia. Based on movement and immersion data collected during the incubation phase of a single breeding season, and from extensive tracking data collected in previous years from different stages of the breeding cycle, we found limited evidence for age-related variation in commonly reported trip parameters, and failed to detect signs of senescent decline. Our results contrast with the limited number of past studies that have examined foraging behaviour in later life, since these have documented changes in performance consistent with senescence. This highlights the importance of studies across different wild animal populations to gain a broader perspective on the processes driving variation in ageing rates.

An agenda for assessing and improving conservation impacts of sustainability standards in tropical agriculture.

Sustainability standards and certification serve to differentiate and provide market recognition to goods produced in accordance with social and environmental good practices, typically including practices to protect biodiversity. Such standards have seen rapid growth, including in tropical agricultural commodities such as cocoa, coffee, palm oil, soybeans, and tea. Given the role of sustainability standards in influencing land use in hotspots of biodiversity, deforestation, and agricultural intensification, much could be gained from efforts to evaluate and increase the conservation payoff of these schemes. To this end, we devised a systematic approach for monitoring and evaluating the conservation impacts of agricultural sustainability standards and for using the resulting evidence to improve the effectiveness of such standards over time. The approach is oriented around a set of hypotheses and corresponding research questions about how sustainability standards are predicted to deliver conservation benefits. These questions are addressed through data from multiple sources, including basic common information from certification audits; field monitoring of environmental outcomes at a sample of certified sites; and rigorous impact assessment research based on experimental or quasi-experimental methods. Integration of these sources can generate time-series data that are comparable across sites and regions and provide detailed portraits of the effects of sustainability standards. To implement this approach, we propose new collaborations between the conservation research community and the sustainability standards community to develop common indicators and monitoring protocols, foster data sharing and synthesis, and link research and practice more effectively. As the role of sustainability standards in tropical land-use governance continues to evolve, robust evidence on the factors contributing to effectiveness can help to ensure that such standards are designed and implemented to maximize benefits for biodiversity conservation.

A global strategy for road building.

The number and extent of roads will expand dramatically this century. Globally, at least 25 million kilometres of new roads are anticipated by 2050; a 60% increase in the total length of roads over that in 2010. Nine-tenths of all road construction is expected to occur in developing nations, including many regions that sustain exceptional biodiversity and vital ecosystem services. Roads penetrating into wilderness or frontier areas are a major proximate driver of habitat loss and fragmentation, wildfires, overhunting and other environmental degradation, often with irreversible impacts on ecosystems. Unfortunately, much road proliferation is chaotic or poorly planned, and the rate of expansion is so great that it often overwhelms the capacity of environmental planners and managers. Here we present a global scheme for prioritizing road building. This large-scale zoning plan seeks to limit the environmental costs of road expansion while maximizing its benefits for human development, by helping to increase agricultural production, which is an urgent priority given that global food demand could double by mid-century. Our analysis identifies areas with high environmental values where future road building should be avoided if possible, areas where strategic road improvements could promote agricultural development with relatively modest environmental costs, and 'conflict areas' where road building could have sizeable benefits for agriculture but with serious environmental damage. Our plan provides a template for proactively zoning and prioritizing roads during the most explosive era of road expansion in human history.

Comparative cognition for conservationists.

Every animal occupies a unique cognitive world based on its sensory capacities, and attentional and learning biases. Behaviour results from the interaction of this cognitive world with the environment. As humans alter environments, cognitive processes ranging from perceptual processes to learned behaviour govern animals' reactions. By harnessing animals' perceptual biases and applying insights from cognitive theory, we can purposefully alter cues to reduce maladaptive responses and shape behaviour. Despite the fundamental connection between cognition and behaviour, the breadth of cognitive theory is underutilised in conservation practice. Bridging these disciplines could augment existing conservation efforts targeting animal behaviour. We outline relevant principles of perception and learning, and develop a step-by-step process for applying aspects of cognition towards specific conservation issues.

BIOFRAG - a new database for analyzing BIOdiversity responses to forest FRAGmentation.

Habitat fragmentation studies have produced complex results that are challenging to synthesize. Inconsistencies among studies may result from variation in the choice of landscape metrics and response variables, which is often compounded by a lack of key statistical or methodological information. Collating primary datasets on biodiversity responses to fragmentation in a consistent and flexible database permits simple data retrieval for subsequent analyses. We present a relational database that links such field data to taxonomic nomenclature, spatial and temporal plot attributes, and environmental characteristics. Field assessments include measurements of the response(s) (e.g., presence, abundance, ground cover) of one or more species linked to plots in fragments within a partially forested landscape. The database currently holds 9830 unique species recorded in plots of 58 unique landscapes in six of eight realms: mammals 315, birds 1286, herptiles 460, insects 4521, spiders 204, other arthropods 85, gastropods 70, annelids 8, platyhelminthes 4, Onychophora 2, vascular plants 2112, nonvascular plants and lichens 320, and fungi 449. Three landscapes were sampled as long-term time series (>10 years). Seven hundred and eleven species are found in two or more landscapes. Consolidating the substantial amount of primary data available on biodiversity responses to fragmentation in the context of land-use change and natural disturbances is an essential part of understanding the effects of increasing anthropogenic pressures on land. The consistent format of this database facilitates testing of generalizations concerning biologic responses to fragmentation across diverse systems and taxa. It also allows the re-examination of existing datasets with alternative landscape metrics and robust statistical methods, for example, helping to address pseudo-replication problems. The database can thus help researchers in producing broad syntheses of the effects of land use. The database is dynamic and inclusive, and contributions from individual and large-scale data-collection efforts are welcome.