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Lessons about parks and poverty from a decade of forest loss and economic growth around Kibale National Park, Uganda: We use field data linked to satellite image analysis to examine the relationship between biodiversity loss, deforestation, and poverty around Kibale National Park (KNP) in western Uganda, 1996–2006. Over this decade, KNP generally maintained forest cover, tree species, and primate populations, whereas neighboring communal forest patches were reduced by half and showed substantial declines in tree species and primate populations. However, a bad decade for forest outside the park proved a prosperous one for most local residents. Panel data for 252 households show substantial improvement in welfare indicators (e.g., safer water, more durable roof material), with the greatest increases found among those with highest initial assets. A combination of regression analysis and matching estimators shows that although the poor tend to be located on the park perimeter, proximity to the park has no measureable effect on growth of productive assets. The risk for land loss among the poor was inversely correlated with proximity to the park, initial farm size, and decline in adjacent communal forests. We conclude the current disproportionate presence of poor households at the edge of the park does not signal that the park is a poverty trap. Rather, Kibale appears to provide protection against desperation sales and farm loss among those most vulnerable. conservation | tropical forest | protected areas | economic development

Newly discovered landscape traps produce regime shifts in wet forests: We describe the “landscape trap” concept, whereby entire landscapes are shifted into, and then maintained (trapped) in, a highly compromised structural and functional state as the result of multiple temporal and spatial feedbacks between human and natural disturbance regimes. The landscape trap concept builds on ideas like stable alternative states and other relevant concepts, but it substantively expands the conceptual thinking in a number of unique ways. In this paper, we (i) review the literature to develop the concept of landscape traps, including their general features; (ii) provide a case study as an example of a landscape trap from the mountain ash (Eucalyptus regnans) forests of southeastern Australia; (iii) suggest how landscape traps can be detected before they are irrevocably established; and (iv) present evidence of the generality of landscape traps in different ecosystems worldwide. altered ecosystem processes | old growth

The search for unknown biodiversity: 1st paragraph: in a world being rapidly transformed by human activities, an alarming possibility is that many species might disappear before we have a chance to study or even scientifically describe them. This possibility goes beyond a simple desire to document biodiversity, because unknown species could have important benefits for humanity. For instance, who might have imagined that an obscure herb endemic to Madagascar, the rosy periwinkle (Catharanthus roseus), would yield the only known treatment for childhood leukemia (1)?

Global land use change, economic globalization, and the looming land scarcity: A central challenge for sustainability is how to preserve forest ecosystems and the services that they provide us while enhancing food production. This challenge for developing countries confronts the force of economic globalization, which seeks cropland that is shrinking in availability and triggers deforestation. Four mechanisms— the displacement, rebound, cascade, and remittance effects—that are amplified by economic globalization accelerate land conversion. A few developing countries have managed a land use transition over the recent decades that simultaneously increased their forest cover and agricultural production. These countries have relied on various mixes of agricultural intensification, land use zoning, forest protection, increased reliance on imported food and wood products, the creation of off-farm jobs, foreign capital investments, and remittances. Sound policies and innovations can therefore rec- oncile forest preservation with food production. Globalization can be harnessed to increase land use efficiency rather than leading to uncontrolled land use expansion. To do so, land systems should be understood and modeled as open systems with large flows of goods, people, and capital that connect local land use with global- scale factors. land change | forest transition food sustainability

Societal challenges in understanding and responding to regime shifts in forest landscapes: 2 excerpts: "The degradation of seminatural landscapes at regional scales, whereby essential functional capabilities and biotic elements are permanently lost as a result of altered disturbance regimes, is a widespread phenomenon." and "Salvage logging of burned or windthrown forests not only eliminates critical structural legacies from predisturbance stands but can disrupt natural regenerative processes, as noted below (10, 11)."

Genome diversity in wild grasses under environmental stress: Patterns of diversity distribution in the Isa defense locus in wild- barley populations suggest adaptive selection at this locus. The extent to which environmental selection may act at additional nuclear-encoded defense loci and within the whole chloroplast genome has now been examined by analyses in two grass species. Analysis of genetic diversity in wild barley (Hordeum spontaneum) defense genes revealed much greater variation in biotic stress-related genes than abiotic stress-related genes. Genetic diversity at the Isa defense locus in wild populations of weeping ricegrass [Microlaena stipoides (Labill.) R. Br.], a very distant wild-rice relative, was more diverse in samples from relatively hotter and drier environments, a phenomenon that reflects observations in wild barley populations. Whole-chloroplast genome sequences of bulked weeping ricegrass individuals sourced from contrasting environments showed higher levels of diversity in the drier environment in both coding and noncoding portions of the genome. Increased genetic diversity may be important in allowing plant populations to adapt to greater environmental variation in warmer and drier climatic conditions. adaptive variation | genomics | molecular evolution | disease resistance | abiotic stress resistance

Satellite-based global-ocean mass balance estimates of interannual variability and emerging trends in continental freshwater discharge: Freshwater discharge from the continents is a key component of Earth’s water cycle that sustains human life and ecosystem health. Surprisingly, owing to a number of socioeconomic and political obstacles, a comprehensive global river discharge observing system does not yet exist. Here we use 13 years (1994–2006) of satellite precipitation, evaporation, and sea level data in an ocean mass balance to estimate freshwater discharge into the global ocean. Results indicate that global freshwater discharge averaged 36,055 km3∕y for the study period while exhibiting significant interannual variability driven primarily by El Niño Southern Oscillation cycles. The method described here can ultimately be used to estimate long-term global discharge trends as the records of sea level rise and ocean temperature lengthen. For the relatively short 13-year period studied here, global discharge increased by 540 km3 ∕y2 , which was largely attributed to an increase of global- ocean evaporation (768 km3 ∕y2 ). Sustained growth of these flux rates into long-term trends would provide evidence for increasing intensity of the hydrologic cycle. climate ∣ global water cycle ∣ hydrology ∣ remote sensing ∣ observations

Ecosystem services: From theory to implementation: Around the world, leaders are increasingly recognizing ecosystems as natural capital assets that supply life-support services of tremendous value. The challenge is to turn this recognition into incentives and institutions that will guide wise investments in natural capital, on a large scale. Advances are required on three key fronts, each featured here: the science of ecosystem production functions and service mapping; the design of appropriate finance, policy, and governance systems; and the art of implementing these in diverse biophysical and social contexts. Scientific understanding of ecosystem production functions is improving rapidly but remains a limiting factor in incorporating natural capital into decisions, via systems of national accounting and other mechanisms. Novel institutional structures are being established for a broad array of services and places, creating a need and opportunity for systematic assessment of their scope and limitations. Finally, it is clear that formal sharing of experience, and defining of priorities for future work, could greatly accelerate the rate of innova- tion and uptake of new approaches.

Evolutionary history and the effect of biodiversity on plant productivity: Loss of biological diversity because of extinction is one of the most pronounced changes to the global environment. For several decades, researchers have tried to understand how changes in biodiversity might impact biomass production by examining how biomass correlates with a number of biodiversity metrics (especially the number of species and functional groups). This body of research has focused on species with the implicit assumption that they are independent entities. However, functional and ecological similarities are shaped by patterns of common ancestry, such that distantly related species might contribute more to production than close relatives, perhaps by increasing niche breadth. Here, we analyze 2 decades of experiments performed in grassland ecosystems throughout the world and examine whether the evolutionary relationships among the species comprising a community predict how biodiversity impacts plant biomass production. We show that the amount of phylogenetic diversity within communities explained significantly more variation in plant community biomass than other measures of diversity, such as the number of species or functional groups. Our results reveal how evolutionary history can provide critical information for understanding, predicting, and potentially ameliorating the effects of biodiversity loss and should serve as an impetus for new biodiversity experiments.

Temperature increase of 21st century mitigation scenarios: Estimates of 21st Century global-mean surface temperature in- crease have generally been based on scenarios that do not include climate policies. Newly developed multigas mitigation scenarios, based on a wide range of modeling approaches and socioeconomic assumptions, now allow the assessment of possible impacts of climate policies on projected warming ranges. This article assesses the atmospheric CO2 concentrations, radiative forcing, and tem- perature increase for these new scenarios using two reduced- complexity climate models. These scenarios result in temperature increase of 0.5–4.4°C over 1990 levels or 0.3–3.4°C less than the no-policy cases. The range results from differences in the assumed stringency of climate policy and uncertainty in our understanding of the climate system. Notably, an average minimum warming of 􏰂1.4°C (with a full range of 0.5–2.8°C) remains for even the most stringent stabilization scenarios analyzed here. This value is sub- stantially above previously estimated committed warming based on climate system inertia alone. The results show that, although ambitious mitigation efforts can significantly reduce global warming, adaptation measures will be needed in addition to mitigation to reduce the impact of the residual warming. climate 􏰀 climate policy 􏰀 stabilization 􏰀 integrated assessment 􏰀 scenario

Impacts of climate change on the world’s most exceptional ecoregions: The current rate of warming due to increases in greenhouse gas (GHG) emissions is very likely unprecedented over the last 10,000 y. Although the majority of countries have adopted the view that global warming must be limited to <2 °C, current GHG emission rates and nonagreement at Copenhagen in December 2009 increase the likelihood of this limit being exceeded by 2100. Extensive evi- dence has linked major changes in biological systems to 20th century warming. The “Global 200” comprises 238 ecoregions of exceptional biodiversity [Olson DM, Dinerstein E (2002) Ann Mo Bot Gard 89:199–224]. We assess the likelihood that, by 2070, these iconic ecoregions will regularly experience monthly climatic conditions that were extreme in 1961–1990. Using >600 realizations from climate model ensembles, we show that up to 86% of terres- trial and 83% of freshwater ecoregions will be exposed to average monthly temperature patterns >2 SDs (2σ) of the 1961–1990 base- line, including 82% of critically endangered ecoregions. The entire range of 89 ecoregions will experience extreme monthly temper- atures with a local warming of <2 °C. Tropical and subtropical ecor- egions, and mangroves, face extreme conditions earliest, some with <1 °C warming. In contrast, few ecoregions within Boreal Forests and Tundra biomes will experience such extremes this cen- tury. On average, precipitation regimes do not exceed 2σ of the baseline period, although considerable variability exists across the climate realizations. Further, the strength of the correlation between seasonal temperature and precipitation changes over nu- merous ecoregions. These results suggest many Global 200 ecore- gions may be under substantial climatic stress by 2100. climate impacts | climate model ensemble | conservation extreme

Protected areas facilitate species’ range expansions: The benefits of protected areas (PAs) for biodiversity have been questioned in the context of climate change because PAs are static, whereas the distributions of species are dynamic. Current PAs may, however, continue to be important if they provide suitable locations for species to colonize at their leading-edge range boundaries, thereby enabling spread into new regions. Here, we present an empirical assessment of the role of PAs as targets for coloniza- tion during recent range expansions. Records from intensive sur- veys revealed that seven bird and butterfly species have colonized PAs 4.2 (median) times more frequently than expected from the availability of PAs in the landscapes colonized. Records of an additional 256 invertebrate species with less-intensive surveys supported these findings and showed that 98% of species are disproportionately associated with PAs in newly colonized parts of their ranges. Although colonizing species favor PAs in general, species vary greatly in their reliance on PAs, reflecting differences in the dependence of individual species on particular habitats and other conditions that are available only in PAs. These findings highlight the importance of current PAs for facilitating range expansions and show that a small subset of the landscape receives a high proportion of colonizations by range-expanding species. conservation | climate change adaptation | nature reserves

Climate negotiations under scientific uncertainty: How does uncertainty about “dangerous” climate change affect the prospects for international cooperation? Climate negotiations usually are depicted as a prisoners’ dilemma game; collectively, countries are better off reducing their emissions, but self-interest impels them to keep on emitting. We provide experimental evidence, grounded in an analytical framework, showing that the fear of crossing a dangerous threshold can turn climate negotiations into a coordination game, making collective action to avoid a dangerous threshold virtually assured. These results are robust to uncertainty about the impact of crossing a threshold, but uncertainty about the location of the threshold turns the game back into a prisoners’ dilemma, causing cooperation to collapse. Our research explains the paradox of why countries would agree to a collective goal, aimed at reducing the risk of catastrophe, but act as if they were blind to this risk.

Soil warming, carbon–nitrogen interactions, and forest carbon budgets: Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming- induced increases in nitrogen availability. This study underscores the importance of incorporating carbon–nitrogen interactions in atmosphere–ocean–land earth system models to accurately simulate land feedbacks to the climate system. climate system feedbacks | ecological stoichiometry | forest carbon budget | forest nitrogen budget | global climate change

Latitudinal variation in lifespan within species is explained by the metabolic theory of ecology: Many ectotherms exhibit striking latitudinal gradients in lifespan. However, it is unclear whether lifespan gradients in distantly related taxa share a common mechanistic explanation. We com- piled data on geographic variation in lifespan in ectotherms from around the globe to determine how much of this intraspecific variation in lifespan may be explained by temperature using the simple predictions of the metabolic theory of ecology. We found that the metabolic theory accurately predicts how lifespan varies with temperature within species in a wide range of ectotherms in both controlled laboratory experiments and free-living populations. After removing the effect of temperature, only a small fraction of species showed significant trends with latitude. There was, however, considerable residual intraspecific variation indi- cating that other, more local factors are likely to be important in determining lifespan within species. These findings suggest that, given predicted increases in global temperature, lifespan of ectotherms may be substantially shortened in the future. ectotherms 􏰀 intraspecific 􏰀 longevity 􏰀 MTE

Global warming benefits the small in aquatic ecosystems: Understanding the ecological impacts of climate change is a crucial challenge of the twenty-first century. There is a clear lack of general rules regarding the impacts of global warming on biota. Here, we present a metaanalysis of the effect of climate change on body size of ectothermic aquatic organisms (bacteria, phyto- and zooplankton, and fish) from the community to the individual level. Using long-term surveys, experimental data and published results, we show a significant increase in the proportion of small-sized species and young age classes and a decrease in size-at-age. These results are in accordance with the ecological rules dealing with the temperature–size relationships (i.e., Bergmann’s rule, James’ rule and Temperature–Size Rule). Our study provides evidence that reduced body size is the third universal ecological response to global warming in aquatic systems besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life cycle events. biological scale 􏰀 body size 􏰀 climate change 􏰀 ectotherms 􏰀 metaanalysis

Nonlinear temperature effects indicate severe damages to U.S. crop yields under climate change: The United States produces 41% of the world’s corn and 38% of the world’s soybeans. These crops comprise two of the four largest sources of caloric energy produced and are thus critical for world food supply. We pair a panel of county-level yields for these two crops, plus cotton (a warmer-weather crop), with a new fine-scale weather dataset that incorporates the whole distribution of tem- peratures within each day and across all days in the growing season. We find that yields increase with temperature up to 29° C for corn, 30° C for soybeans, and 32° C for cotton but that tem- peratures above these thresholds are very harmful. The slope of the decline above the optimum is significantly steeper than the incline below it. The same nonlinear and asymmetric relationship is found when we isolate either time-series or cross-sectional variations in temperatures and yields. This suggests limited his- torical adaptation of seed varieties or management practices to warmer temperatures because the cross-section includes farmers’ adaptations to warmer climates and the time-series does not. Holding current growing regions fixed, area-weighted average yields are predicted to decrease by 30 – 46% before the end of the century under the slowest (B1) warming scenario and decrease by 63–82% under the most rapid warming scenario (A1FI) under the Hadley III model. agriculture 􏰀 panel analysis 􏰀 time series 􏰀 cross section 􏰀 farmer adaptation

Temperature sensitivity of drought-induced tree mortality portends increased regional die-off under global change-type drought: Large-scale biogeographical shifts in vegetation are predicted in response to the altered precipitation and temperature regimes associated with global climate change. Vegetation shifts have profound ecological impacts and are an important climate-ecosystem feedback through their alteration of carbon, water, and energy exchanges of the land surface. Of particular concern is the potential for warmer temperatures to compound the effects of increasingly severe droughts by triggering widespread vegetation shifts via woody plant mortality. The sensitivity of tree mortality to temperature is dependent on which of 2 non-mutually-exclusive mechanisms predominates—temperature-sensitive carbon starvation in response to a period of protracted water stress or temperature-insensitive sudden hydraulic failure under extreme water stress (cavitation). Here we show that experimentally induced warmer temperatures (􏰂4 °C) shortened the time to drought- induced mortality in Pinus edulis (pin ̃ on shortened pine) trees by nearly a third, with temperature-dependent differences in cumu- lative respiration costs implicating carbon starvation as the primary mechanism of mortality. Extrapolating this temperature effect to the historic frequency of water deficit in the southwestern United States predicts a 5-fold increase in the frequency of regional-scale tree die-off events for this species due to temperature alone. Projected increases in drought frequency due to changes in pre- cipitation and increases in stress from biotic agents (e.g., bark beetles) would further exacerbate mortality. Our results demon- strate the mechanism by which warmer temperatures have exac- erbated recent regional die-off events and background mortality rates. Because of pervasive projected increases in temperature, our results portend widespread increases in the extent and frequency of vegetation die-off. biosphere–atmosphere feedbacks 􏰀 drought impacts 􏰀 global-change ecology 􏰀 Pinus edulis 􏰀 carbon starvation

Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time: Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO2 between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO2 (gcmax) to sites of assimi- lation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO2, the crucial significance of similarly large variations in S has been overlooked. Here, we use physical diffusion theory to explain why large changes in S nec- essarily accompanied the changes in D and atmospheric CO2 over the last 400 million years. In particular, we show that high densities of small stomata are the only way to attain the highest gcmax values required to counter CO2‘‘starvation’’ at low atmospheric CO2 concentrations. This explains cycles of increasing D and decreasing S evident in the fossil history of stomata under the CO2 impover- ished atmospheres of the Permo-Carboniferous and Cenozoic gla- ciations. The pattern was reversed under rising atmospheric CO2 regimes. Selection for small S was crucial for attaining high gcmax under falling atmospheric CO2 and, therefore, may represent a mechanism linking CO2 and the increasing gas-exchange capacity of land plants over geologic time. Phanerozoic 􏰀 photosynthesis 􏰀 plant evolution 􏰀 transpiration 􏰀 xylem

Irreversible climate change due to carbon dioxide emissions: The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450 – 600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the ‘‘dust bowl’’ era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4–1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6 –1.9 m for peak CO2 concentrations exceeding 1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer. dangerous interference 􏰀 precipitation 􏰀 sea level rise 􏰀 warming

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