Search

Tree establishment following severe or stand-replacing disturbance is critical for achieving U.S. climate change mitigation goals and for maintaining the co-benefits of intact forest ecosystems. In many contexts, natural post-fire tree regeneration is sufficient to maintain forest cover and associated ecosystem services, but increasingly the pattern and scale of disturbance exceeds ecological thresholds and active reforestation may be warranted. Our capacity to plant trees, however, is not keeping pace with reforestation needs. This shortfall is uniquely apparent in the western U.S., where wildfire size and severity have increased in recent decades and long-term divestment in the reforestation supply chain has limited our ability to respond to existing needs. Here we present an analysis of key facets of both the supply and demand side of reforestation in the western U.S. and address six questions: (1) What is the current backlog of potential reforestation needs driven by high-severity wildfire?; (2) How will increasing wildfire activity through the end of the century affect potential reforestation needs?; (3) What is our capacity to meet current and future reforestation needs?; (4) How can we scale the reforestation supply chain to meet current and future demands?; (5) What approaches to reforestation can promote forest resilience to climate change and wildfire?; and (6) Where are opportunities emerging from recent policy initiatives, innovative public-private partnerships, and natural capital markets for scaling reforestation? Between 1984 and 2000, annual tree planting capacity met post-fire needs but cumulatively over the last two decades (2000 to 2021) it has fallen short of fire-driven needs by an estimated 1.5 million ha (ca. 3.8 million ac). We anticipate this gap will increase 2 to 3 fold by 2050. Scaling up reforestation efforts to close this gap will require increased investment across all facets of the reforestation supply chain, public-private partnerships, and novel approaches to reforestation that increase the resilience of western forests to drought and wildfire. We highlight emerging opportunities from recent policy initiatives and conservation finance for expanding reforestation efforts. [ABSTRACT FROM AUTHOR]

The scale and pace of energy infrastructure development required to achieve netzero greenhouse gas (GHG) emissions are unprecedented, yet our understanding of how to minimize its potential impacts on land and ocean use and natural resources is inadequate. Using high-resolution energy and land-use modeling, we developed spatially explicit scenarios for reaching an economy-wide net-zero GHG target in the western United States by 2050. We found that among net-zero policy cases that vary the rate of transportation and building electrification and use of fossil fuels, nuclear generation, and biomass, the "High Electrification" case, which utilizes electricity generation the most efficiently, had the lowest total land and ocean area requirements (84,000 to 105,000 km² vs. 88,100 to 158,000 km² across all other cases). Different levels of land and ocean use protections were applied to determine their effect on siting, environmental and social impacts, and energy costs. Meeting the net-zero target with stronger land and ocean use protections did not significantly alter the share of different energy generation technologies and only increased system costs by 3%, but decreased additional interstate transmission capacity by 20%. Yet, failure to avoid development in areas with high conservation value is likely to result in substantial habitat loss. [ABSTRACT FROM AUTHOR]

Meeting ambitious climate targets will require deploying the full suite of mitigation options, including those that indirectly reduce greenhouse-gas (GHG) emissions. Healthy diets have sustainability co-benefits by directly reducing livestock emissions as well as indirectly reducing land use emissions. Increased crop productivity could indirectly avoid emissions by reducing cropland area. However, there is disagreement on the sustainability of proposed healthy U.S. diets and a lack of clarity on how long-term sustainability benefits may change in response to shifts in the livestock sector. Here, we explore the GHG emissions impacts of seven scenarios that vary U.S. crop yields and healthier diets in the U.S. and overseas. We also examine how impacts vary across assumptions of future ruminant livestock productivity and ruminant stocking density in the U.S. We employ two complementary land use models—the US FABLE Calculator, an agricultural and forestry sector accounting model with high agricultural commodity representation, and GLOBIOM, a spatially explicit partial equilibrium optimization model for global land use systems. Results suggest that healthier U.S. diets that follow the Dietary Guidelines for Americans reduce agricultural and land use greenhouse gas emissions by 25–57% (approx 120–310 MtCO2e/y) and pastureland area by 28–38%. The potential emissions and land sparing benefits of U.S. agricultural productivity growth are modest within the U.S. due to the increasing comparative advantage of U.S. crops. Our findings suggest that healthy U.S. diets can significantly contribute toward meeting U.S. long-term climate goals for the land use sectors. [ABSTRACT FROM AUTHOR]

New land protection is expensive, and many conservation NGOs rely on loans to help fund land acquisition in the short term. Conservation loans are offered by a range of philanthropic organizations that often allow much more flexible terms than traditional loans. Thus, conservation loans may behave differently from other types of loan. There are costs and benefits to relying on loan financing to fund land protection that organizations need to consider, but few data are available to inform such evaluations. Here, we focus on estimating the financial cost of these loans, by analyzing loans used to support land protection projects that were provided through an internal revolving fund at a large U.S. conservation NGO. We estimate loan financing cost through accrued interest and test deal‐level characteristics for their ability to explain or predict loan interest. We find that loan performance can be highly uncertain and costs can be substantial in relation to the total purchase price. An improved ability to estimate the overall cost of conservation loans upfront may determine just which conservation projects are prioritized for investment and avoid costly misallocations of conservation resources. [ABSTRACT FROM AUTHOR]

Funding for protected areas is limited and recurrent costs associated with managing these sites must be considered in planning their acquisition. However, most conservation planning studies either ignore management costs or use snapshot estimates, even though they vary through time. We surveyed expenditures on management made over 15 years for 37 protected areas in the Appalachians that were established by a large land trust (TNC). These management costs varied greatly through both time and space. We explored what ecological and socioeconomic characteristics explain this variation. Management costs increased with site area but exhibited economies of scale. They were also greater for sites presenting a more rugged terrain and surrounded by a denser combination of roads and urban areas. Prescribed burns were strong drivers of expenditures in the years they occur, while acquisition costs were negatively correlated to subsequent expenditures on management. Land managers felt that protected areas that received less management effort were in worse condition and tended to spend more on areas with greater estimated species richness. Better accounting of how management costs vary in space and time can help conservation organizations allocate their limited resources effectively and to evaluate the likely long‐term cost implications of expanding protected area networks. [ABSTRACT FROM AUTHOR]

To help avoid the most catastrophic effects of climate change, society needs to achieve net-zero greenhouse gas emissions by mid-century. Wind energy provides a clean, renewable source of electricity; however, improperly sited wind facilities pose known threats to wildlife populations and contribute to degradation of natural habitats. To support a rapid transition to low-carbon energy while protecting imperiled species, we identified potential low-impact areas for wind development in a 19-state region of the central U.S. by excluding areas with known wildlife sensitivities. By combining maps of sensitive habitats and species with wind speed and land use information, we demonstrate that there is significant potential to develop wind energy in the region while avoiding significant negative impacts to wildlife. These low-impact areas have the potential to yield between 930 and 1550 GW of name-plate wind capacity. This is equivalent to 8–13 times current U.S. installed wind capacity. Our analysis demonstrates that ambitious low-carbon energy goals are achievable while minimizing risks to wildlife. [ABSTRACT FROM AUTHOR]

Single species conservation unites disparate partners for the conservation of one species. However, there are widespread concerns that single species conservation biases conservation efforts towards charismatic species at the expense of others. Here we investigate the extent to which sage grouse (Centrocercus sp.) conservation, the largest public-private conservation effort for a single species in the US, provides protections for other species from localized and landscape-scale threats. We compared the coverage provided by sage grouse Priority Areas for Conservation (PACs) to 81 sagebrush-associated vertebrate species distributions with potential coverage under multi-species conservation prioritization generated using the decision support tool Zonation. PACs. We found that the current PAC prioritization approach was not statistically different from a diversity-based prioritization approach and covers 23.3% of the landscape, and 24.8%, on average, of the habitat of the 81 species. The proportion of each species distribution at risk was lower inside PACs as compared to the region as a whole, even without management (land use change 30% lower, cheatgrass invasion 19% lower). Whether or not bias away from threat represents the most efficient use of conservation effort is a matter of considerable debate, though may be pragmatic in this landscape where capacity to address these threats is limited. The approach outlined here can be used to evaluate biological equitability of protections provided by flagship species in other settings. [ABSTRACT FROM AUTHOR]

A hopeful vision of the future is a world in which both people and nature thrive, but there is little evidence to support the feasibility of such a vision. We used a global, spatially explicit, systems modeling approach to explore the possibility of meeting the demands of increased populations and economic growth in 2050 while simultaneously advancing multiple conservation goals. Our results demonstrate that if, instead of "business as usual" practices, the world changes how and where food and energy are produced, this could help to meet projected increases in food (54%) and energy (56%) demand while achieving habitat protection (>50% of natural habitat remains unconverted in most biomes globally; 17% area of each ecoregion protected in each country), reducing atmospheric greenhouse‐gas emissions consistent with the Paris Climate Agreement (≤1.6°C warming by 2100), ending overfishing, and reducing water stress and particulate air pollution. Achieving this hopeful vision for people and nature is attainable with existing technology and consumption patterns. However, success will require major shifts in production methods and an ability to overcome substantial economic, social, and political challenges. [ABSTRACT FROM AUTHOR]

Unprecedented rates of urbanization are changing our understanding of the ways in which children build connections to the natural world, including the importance of educational settings in affecting this relationship. In addition to influencing human-nature connection, greenspace around school grounds has been associated with benefits to students' cognitive function. Questions remain regarding the size of this benefit relative to other factors, and which features of greenspace are responsible for these effects. We conducted a large-scale correlative study subsampling elementary schools (n = 495) in ecologically, socially and economically diverse California. After controlling for common educational determinants (e.g., socio-economic status, race/ethnicity, student teacher ratio, and gender ratio) we found a significant, positive association between test scores and tree and shrub cover within 750 and 1000 m of urban schools. Tree and shrub cover was not associated with test scores in rural schools or five buffers closer to urban schools (10, 50, 100, 300, and 500 m). Two other greenspace variables (NDVI and agricultural area) were not associated with test performance at any of the analyzed buffer distances for rural or urban schools. Minority representation had the largest effect size on standardized test scores (8.1% difference in scores with 2SD difference in variable), followed by tree and shrub cover around urban schools, which had a large effect size (2.9–3.0% at 750 and 1000 m) with variance from minority representation and socioeconomic status (effect size 2.4%) included. Within our urban sample, average tree-cover schools performed 4.2% (3.9–4.4, and 95% CI) better in terms of standardized test scores than low tree-cover urban schools. Our findings support the conclusion that neighborhood-scale (750–1000 m) urban tree and shrub cover is associated with school performance, and indicate that this element of greenspace may be an important factor to consider when studying the cognitive impacts of the learning environment. These results support the design of experimental tests of tree planting interventions for educational benefits. [ABSTRACT FROM AUTHOR]

Conservation organizations must redouble efforts to protect habitat given continuing biodiversity declines. Prioritization of future areas for protection is hampered by disagreements over what the ecological targets of conservation should be. Here we test the claim that such disagreements will become less important as conservation moves away from prioritizing areas for protection based only on ecological considerations and accounts for varying costs of protection using return-on-investment (ROI) methods. We combine a simulation approach with a case study of forests in the eastern United States, paying particular attention to how covariation between ecological benefits and economic costs influences agreement levels. For many conservation goals, agreement over spatial priorities improves with ROI methods. However, we also show that a reliance on ROI-based prioritization can sometimes exacerbate disagreements over priorities. As such, accounting for costs in conservation planning does not enable society to sidestep careful consideration of the ecological goals of conservation [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Protection of lands threatened with conversion to agriculture can reduce carbon emissions. Until recently, most climate change mitigation incentive programs for avoided conversion have focused on forested ecosystems. We applied the Avoided Conversion of Grasslands and Shrublands v.1.0 ( ACo GS) methodology now available through the American Carbon Registry to a threatened region of grasslands in the northern Great Plains. For all soil types across 14 counties in North and South Dakota, we used the DAYCENT model calibrated to the study area to quantify the difference in CO2 and N2O emissions under a cropping and a protection scenario, and we used formulas in the ACo GS methodology to calculate CH4 emissions from enteric fermentation under the protection scenario. We mapped the resulting GHG emissions across the entire project area. Emissions averaged 51.6 tCO2e/ha over 20 years, and with a 31% reduction for leakage and uncertainty from the ACo GS methodology, carbon offsets averaged 35.6 tCO2e/ha over 20 years. Protection of 10% of the 2.1 million unprotected ha in the project area with the highest emissions would reduce emissions by 11.7 million tCO2e over 20 years (11% of the total emissions from all unprotected grassland) and avoid a social cost of $430 million worth of CO2 emissions. These results suggest that carbon offsets generated from avoided conversion of grasslands can meaningfully contribute to climate mitigation and grassland conservation objectives. [ABSTRACT FROM AUTHOR]

Energy production in the United States for domestic use and export is predicted to rise 27% by 2040. We quantify projected energy sprawl (new land required for energy production) in the United States through 2040. Over 200,000 km2 of additional land area will be directly impacted by energy development. When spacing requirements are included, over 800,000 km2 of additional land area will be affected by energy development, an area greater than the size of Texas. This pace of development in the United States is more than double the historic rate of urban and residential development, which has been the greatest driver of conversion in the United States since 1970, and is higher than projections for future land use change from residential development or agriculture. New technology now places 1.3 million km2 that had not previously experienced oil and gas development at risk of development for unconventional oil and gas. Renewable energy production can be sustained indefinitely on the same land base, while extractive energy must continually drill and mine new areas to sustain production. We calculated the number of years required for fossil energy production to expand to cover the same area as renewables, if both were to produce the same amount of energy each year. The land required for coal production would grow to equal or exceed that of wind, solar and geothermal energy within 2–31 years. In contrast, it would take hundreds of years for oil production to have the same energy sprawl as biofuels. Meeting energy demands while conserving nature will require increased energy conservation, in addition to distributed renewable energy and appropriate siting and mitigation. [ABSTRACT FROM AUTHOR]

We examine the efficiency with which a suite of ecosystem services can be restored by different reforestation configurations. We use a spatial analysis to quantify the ecosystem service trade-offs and synergies of five equal-area, large-scale bottomland hardwood reforestation scenarios for a study area in the Mississippi Alluvial Valley. Each reforestation configuration is designed to achieve a different environmental objective: nutrient retention, intact riparian and floodplain areas, forest breeding bird habitat, and black bear habitat connectivity. A random reforestation of the same area is also created to represent an opportunistically driven scenario. The opportunistic reforestation delivered services between 85% and 94% less efficiently than targeted reforestation. We also find a distinct service trade-off between reforestation to address water quality and reforestation to provide habitat for large vertebrates. This analysis underscores the importance of spatially quantifying ecosystem services and their trade-offs when seeking to optimize the ecosystem service benefits of restoration. [ABSTRACT FROM AUTHOR]

High yields are a priority in managing biomass for renewable energy, but the environmental impacts of various feedstocks and production systems should be equally considered. Mixed-species, perennial grasslands enrolled in conservation programs are being considered as a source of biomass for renewable energy. Conservation grasslands are crucial in sustaining native biodiversity throughout the US Upper Midwest, and the effects of biomass harvest on biodiversity are largely unknown. We measured the effect of late-season biomass harvest on plant community composition in conservation grasslands in three regions of Minnesota, USA from 2009 to 2012. Temporal trends in plant species composition within harvested grasslands were compared to unharvested grasslands using mixed effects models. A before-after control-impact approach using effect sizes was applied to focus on pre- and postharvest conditions. Production-scale biomass harvest did not affect plant species richness, species or functional group diversity, nor change the relative abundance of the main plant functional groups. Differences in the relative abundances of plant functional groups were observed across locations; and at some locations, changed through time. The proportion of non-native species remained constant, while the proportion of noxious weeds decreased through time in both harvested and unharvested grasslands at the central location. Ordination revealed patterns in species composition due to location, but not due to harvest treatment. Therefore, habitat and bioenergy characteristics related to grassland plant communities are not expected to change due to short-term or intermittent late-season biomass harvest. [ABSTRACT FROM AUTHOR]

Bioenergy deployment offers significant potential for climate change mitigation, but also carries considerable risks. In this review, we bring together perspectives of various communities involved in the research and regulation of bioenergy deployment in the context of climate change mitigation: Land-use and energy experts, land-use and integrated assessment modelers, human geographers, ecosystem researchers, climate scientists and two different strands of life-cycle assessment experts. We summarize technological options, outline the state-of-the-art knowledge on various climate effects, provide an update on estimates of technical resource potential and comprehensively identify sustainability effects. Cellulosic feedstocks, increased end-use efficiency, improved land carbon-stock management and residue use, and, when fully developed, BECCS appear as the most promising options, depending on development costs, implementation, learning, and risk management. Combined heat and power, efficient biomass cookstoves and small-scale power generation for rural areas can help to promote energy access and sustainable development, along with reduced emissions. We estimate the sustainable technical potential as up to 100 EJ: high agreement; 100-300 EJ: medium agreement; above 300 EJ: low agreement. Stabilization scenarios indicate that bioenergy may supply from 10 to 245 EJ yr−1 to global primary energy supply by 2050. Models indicate that, if technological and governance preconditions are met, large-scale deployment (>200 EJ), together with BECCS, could help to keep global warming below 2° degrees of preindustrial levels; but such high deployment of land-intensive bioenergy feedstocks could also lead to detrimental climate effects, negatively impact ecosystems, biodiversity and livelihoods. The integration of bioenergy systems into agriculture and forest landscapes can improve land and water use efficiency and help address concerns about environmental impacts. We conclude that the high variability in pathways, uncertainties in technological development and ambiguity in political decision render forecasts on deployment levels and climate effects very difficult. However, uncertainty about projections should not preclude pursuing beneficial bioenergy options. [ABSTRACT FROM AUTHOR]

Payments for ecosystem services (PES) can improve environmental quality by aligning the incentives of individual landowners with societal interests in providing valuable ecosystem services such as carbon storage, water quality, flood control, and wildlife habitat. However, for this potential to be realized, many institutional details and technical challenges must be addressed. In this review, we discuss six critical issues for creating effective PES markets: using the appropriate type of market institution, defining suitable spatial and temporal scales for the market, promoting additionality (avoiding payments for services that would have been provided even in the absence of payments) so that payments result in increased services, offering incentives for projects that generate multiple ecosystem services, considering practice-based versus performance-based payments, and eliminating opportunities for strategic behavior aimed at "gaming the system". We illustrate these issues with an example of how PES could be applied to floodplain restoration. [ABSTRACT FROM AUTHOR]

Perennial biomass from grasslands managed for conservation of soil and biodiversity can be harvested for bioenergy. Until now, the quantity and quality of harvestable biomass from conservation grasslands in Minnesota, USA, was not known, and the factors that affect bioenergy potential from these systems have not been identified. We measured biomass yield, theoretical ethanol conversion efficiency, and plant tissue nitrogen (N) as metrics of bioenergy potential from mixed-species conservation grasslands harvested with commercial-scale equipment. With three years of data, we used mixed-effects models to determine factors that influence bioenergy potential. Sixty conservation grassland plots, each about 8 ha in size, were distributed among three locations in Minnesota. Harvest treatments were applied annually in autumn as a completely randomized block design. Biomass yield ranged from 0.5 to 5.7 Mg ha−1. May precipitation increased biomass yield while precipitation in all other growing season months showed no affect. Averaged across all locations and years, theoretical ethanol conversion efficiency was 450 l Mg−1 and the concentration of plant N was 7.1 g kg−1, both similar to dedicated herbaceous bioenergy crops such as switchgrass. Biomass yield did not decline in the second or third year of harvest. Across years, biomass yields fluctuated 23% around the average. Surprisingly, forb cover was a better predictor of biomass yield than warm-season grass with a positive correlation with biomass yield in the south and a negative correlation at other locations. Variation in land ethanol yield was almost exclusively due to variation in biomass yield rather than biomass quality; therefore, efforts to increase biomass yield might be more economical than altering biomass composition when managing conservation grasslands for ethanol production. Our measurements of bioenergy potential, and the factors that control it, can serve as parameters for assessing the economic viability of harvesting conservation grasslands for bioenergy. [ABSTRACT FROM AUTHOR]

Rising energy consumption in coming decades, combined with a changing energy mix, have the potential to increase the impact of energy sector water use on freshwater biodiversity. We forecast changes in future water use based on various energy scenarios and examine implications for freshwater ecosystems. Annual water withdrawn/manipulated would increase by 18-24%, going from 1,993,000-2,628,000 Mm³ in 2010 to 2,359,000-3,271,000 Mm³ in 2035 under the Reference Case of the Energy Information Administration (EIA). Water consumption would more rapidly increase by 26% due to increased biofuel production, going from 16,700-46,400 Mm³ consumption in 2010 to 21,000-58,400 Mm³ consumption in 2035. Regionally, water use in the Southwest and Southeast may increase, with anticipated decreases in water use in some areas of the Midwest and Northeast. Policies that promote energy efficiency or conservation in the electric sector would reduce water withdrawn/manipulated by 27-36 m³GJ-1 (0.1-0.5 m³GJ-1 consumption), while such policies in the liquid fuel sector would reduce withdrawal/manipulation by 0.4-0.7 m³GJ-1 (0.2-0.3 m³GJ-1 consumption). The greatest energy sector withdrawal/manipulation are for hydropower and thermoelectric cooling, although potential new EPA rules that would require recirculating cooling for thermoelectric plants would reduce withdrawal/manipulation by 441,000 Mm³ (20,300 Mm³ consumption). The greatest consumptive energy sector use is evaporation from hydroelectric reservoirs, followed by irrigation water for biofuel feedstocks and water used for electricity generation from coal. Historical water use by the energy sector is related to patterns of fish species endangerment, where water resource regions with a greater fraction of available surface water withdrawn by hydropower or consumed by the energy sector correlated with higher probabilities of imperilment. Since future increases in energy-sector surface water use will occur in areas of high fish endemism (e.g., Southeast), additional management and policy actions will be needed to minimize further species imperilment. [ABSTRACT FROM AUTHOR]

Nutrient addition to grasslands consistently causes species richness declines and productivity increases. Competition, particularly for light, is often assumed to produce this result. Using a long-term dataset from North American herbaceous plant communities, we tested whether height and clonal growth form together predict responses to fertilization because neither trait alone predicted species loss in a previous analysis. Species with a tall-runner growth form commonly increased in relative abundance in response to added nitrogen, while short species and those with a tall-clumped clonal growth form often decreased. The ability to increase in size via vegetative spread across space, while simultaneously occupying the canopy, conferred competitive advantage, although typically only the abundance of a single species within each height-clonal growth form significantly responded to fertilization in each experiment. Classifying species on the basis of two traits (height and clonal growth form) increases our ability to predict species responses to fertilization compared to either trait alone in predominantly herbaceous plant communities. [ABSTRACT FROM AUTHOR]

Wind energy offers the potential to reduce carbon emissions while increasing energy independence and bolstering economic development. However, wind energy has a larger land footprint per Gigawatt (GW) than most other forms of energy production and has known and predicted adverse effects on wildlife. The Northern Great Plains (NGP) is home both to some of the world's best wind resources and to remaining temperate grasslands, the most converted and least protected ecological system on the planet. Thus, appropriate siting and mitigation of wind development is particularly important in this region. Steering energy development to disturbed lands with low wildlife value rather than placing new developments within large and intact habitats would reduce impacts to wildlife. Goals for wind energy development in the NGP are roughly 30 GW of nameplate capacity by 2030. Our analyses demonstrate that there are large areas where wind development would likely have few additional impacts on wildlife. We estimate there are -1,056 GW of potential wind energy available across the NGP on areas likely to have low-impact for biodiversity, over 35 times development goals. New policies and approaches will be required to guide wind energy development to low-impact areas. [ABSTRACT FROM AUTHOR]

Summary 1. Community assembly theories predict that the success of invading species into a new community should be predictable by functional traits. Environmental filters could constrain the number of successful ecological strategies in a habitat, resulting in similar suites of traits between native and successfully invading species (convergence). Conversely, concepts of limiting similarity and competitive exclusion predict native species will prevent invasion by functionally similar exotic species, resulting in trait divergence between the two species pools. Nutrient availability may further alter the strength of convergent or divergent forces in community assembly, by relaxing environmental constraints and/or influencing competitive interactions. 2. To investigate how nutrient availability influences forces of divergence and convergence during the invasion of exotic species into native communities, we conducted multivariate analyses of community composition and functional traits from naturally assembled plant communities in long-term nitrogen (N) addition experiments across North America. 3. Relative abundances of key functional traits differed between the native and exotic plant communities, consistent with limiting similarity or a trait bias in the exotic species pool. Environmental context also played an important role in invasion because sites varied in the identity of the traits that predicted dissimilarity between native and exotic communities. Nitrogen enrichment did not alter these patterns. 4. Nitrogen enrichment tended to increase exotic abundance, but this result was driven by a dramatic increase in exotics in only a few experiments. When similarity between native and exotic communities was included in the statistical model, N enrichment no longer predicted an increase in exotic relative abundance. Instead, sites with the highest abundance of exotic species were the ones where native and exotic communities had the highest trait similarity. 5. Synthesis. Our analysis of natural patterns of invasion across herbaceous communities in North America found evidence of both divergent and convergent forces on community assembly with exotic species. Together, these results suggest that while functionally dissimilar exotic species may be more likely to invade, they are unlikely to become abundant unless they have traits pre-adapting them to environmental conditions in their invaded range. Contrary to prior studies, invasion was not consistently promoted by N enrichment. [ABSTRACT FROM AUTHOR]

Wind energy, if improperly sited, can impact wildlife through direct mortality and habitat loss and fragmentation, in contrast to its environmental benefits in the areas of greenhouse gas, air quality, and water quality. Fortunately, risks to wildlife from wind energy may be alleviated through proper siting and mitigation offsets. Here we identify areas in Kansas where wind development is incompatible with conservation, areas where wind development may proceed but with compensatory mitigation for impacts, and areas where development could proceed without the need for compensatory mitigation. We demonstrate that approximately 10.3 million ha in Kansas (48 percent of the state) has the potential to provide 478 GW of installed capacity while still meeting conservation goals. Of this total, approximately 2.7 million ha would require no compensatory mitigation and could produce up to 125 GW of installed capacity. This is 1,648 percent higher than the level of wind development needed in Kansas by 2030 if the United States is to get 20 percent of its electricity from wind. Projects that avoid and offset impacts consistent with this analysis could be awarded ''Green Certification.'' Certification may help to expand and sustain the wind industry by facilitating the completion of individual projects sited to avoid sensitive areas and protecting the industry's reputation as an ecologically friendly source of electricity. [ABSTRACT FROM AUTHOR]

Previous national and global conservation assessments have relied on habitat conversion data to quantify conservation risk. However, in addition to habitat conversion to crop production or urban uses, ecosystem alteration (e.g., from logging, conversion to plantations, biological invasion, or fire suppression) is a large source of conservation risk. We add data quantifying ecosystem alteration on unconverted lands to arrive at a more accurate depiction of conservation risk for the conterminous United States. We quantify ecosystem alteration using a recent national assessment based on remote sensing of current vegetation compared with modeled reference natural vegetation conditions. Highly altered (but not converted) ecosystems comprise 23% of the conterminous United States, such that the number of critically endangered ecoregions in the United States is 156% higher than when calculated using habitat conversion data alone. Increased attention to natural resource management will be essential to address widespread ecosystem alteration and reduce conservation risk. [ABSTRACT FROM AUTHOR]

In many economies, wealth is strikingly concentrated. Entrepreneurs-individuals with ownership in for-profit enterprises- comprise a large portion of the wealthiest individuals, and their behavior may help explain patterns in the national distribution of wealth. Entrepreneurs are less diversified and more heavily invested in their own companies than is commonly assumed in economic models. We present an intentionally simplified individual-based model of wealth generation among entrepreneurs to assess the role of chance and determinism in the distribution of wealth. We demonstrate that chance alone, combined with the deterministic effects of compounding returns, can lead to unlimited concentration of wealth, such that the percentage of all wealth owned by a few entrepreneurs eventually approaches 100%. Specifically, concentration of wealth results when the rate of return on investment varies by entrepreneur and by time. This result is robust to inclusion of realities such as differing skill among entrepreneurs. The most likely overall growth rate of the economy decreases as businesses become less diverse, suggesting that high concentrations of wealth may adversely affect a country's economic growth. We show that a tax on large inherited fortunes, applied to a small portion of the most fortunate in the population, can efficiently arrest the concentration of wealth at intermediate levels. [ABSTRACT FROM AUTHOR]

The article focuses on the biofuels and biodiversity in the U.S. It says that biofuel production in the country has obtained political support, particularly in agricultural sector, which is visible in the production tax credit for ethanol used as transportation fuel and import tariff on foreign ethanol. It mentions that the new land for biofuel production could have a big impact on carbon emissions and biodiversity in the country.

Demand for land to grow corn for ethanol increased in the United States by 4.9 million hectares between 2005 and 2008, with wide-ranging effects on wildlife, including habitat loss. Depending on how biofuels are made, additional production could have similar impacts. We present a framework for assessing the impacts of biofuels on wildlife, and we use this framework to evaluate the impacts of existing and emerging biofuels feedstocks on grassland wildlife. Meeting the growing demand for biofuels while avoiding negative impacts on wildlife will require either biomass sources that do not require additional land (e.g., wastes, residues, cover crops, algae) or crop production practices that are compatible with wildlife. Diverse native prairie offers a potential approach to bioenergy production (including fuel, electricity, and heat) that is compatible with wildlife. Additional research is required to assess the compatibility of wildlife with different composition, inputs, and harvest management approaches, and to address concerns over prairie yields versus the yields of other biofuel crops. [ABSTRACT FROM AUTHOR]

Concern over climate change has led the U.S. to consider a cap-and-trade system to regulate emissions. Here we illustrate the land-use impact to U.S. habitat types of new energy development resulting from different U.S. energy policies. We estimated the total new land area needed by 2030 to produce energy, under current law and under various cap-and-trade policies, and then partitioned the area impacted among habitat types with geospatial data on the feasibility of production. The land-use intensity of different energy production techniques varies over three orders of magnitude, from 1.9-2.8 km²/TW hr/yr for nuclear power to 788-1000 km²/TW hr/yr for biodiesel from soy. In all scenarios, temperate deciduous forests and temperate grasslands will be most impacted by future energy development, although the magnitude of impact by wind, biomass, and coal to different habitat types is policy-specific. Regardless of the existence or structure of a cap-and-trade bill, at least 206,000 km² will be impacted without substantial increases in energy efficiency, which saves at least 7.6 km² per TW hr of electricity conserved annually and 27.5 km² per TW hr of liquid fuels conserved annually. Climate policy that reduces carbon dioxide emissions may increase the areal impact of energy, although the magnitude of this potential side effect may be substantially mitigated by increases in energy efficiency. The possibility of widespread energy sprawl increases the need for energy conservation, appropriate siting, sustainable production practices, and compensatory mitigation offsets. [ABSTRACT FROM AUTHOR]

Most explanations for the positive effect of plant species diversity on productivity have focused on the efficiency of resource use, implicitly assuming that resource supply is constant. To test this assumption, we grew seedlings of Echinacea purpurea in soil collected beneath 10-year-old, experimental plant communities containing one, two, four, eight, or 16 native grassland species. The results of this greenhouse bioassay challenge the assumption of constant resource supply; we found that bioassay seedlings grown in soil collected from experimental communities containing 16 plant species produced 70% more biomass than seedlings grown in soil collected beneath monocultures. This increase was likely attributable to greater soil N availability, which had increased in higher diversity communities over the 10-year-duration of the experiment. In a distinction akin to the selection/complementarity partition commonly made in studies of diversity and productivity, we further determined whether the additive effects of functional groups or the interactive effects of functional groups explained the increase in fertility with diversity. The increase in bioassay seedling biomass with diversity was largely explained by a concomitant increase in N-fixer, C4 grass, forb, and C3 grass biomass with diversity, suggesting that the additive effects of these four functional groups at higher diversity contributed to enhance N availability and retention. Nevertheless, diversity still explained a significant amount of the residual variation in bioassay seedling biomass after functional group biomass was included in a multiple regression, suggesting that interactions also increased fertility in diverse communities. Our results suggest a mechanism, the fertility effect, by which increased plant species diversity may increase community productivity over time by increasing the supply of nutrients via both greater inputs and greater retention. [ABSTRACT FROM AUTHOR]

Global energy use and food production have increased nitrogen inputs to ecosystems worldwide, impacting plant community diversity, composition, and function. Previous studies show considerable variation across terrestrial herbaceous ecosystems in the magnitude of species loss following nitrogen (N) enrichment. What controls this variation remains unknown. We present results from 23 N-addition experiments across North America, representing a range of climatic, soil and plant community properties, to determine conditions that lead to greater diversity decline. Species loss in these communities ranged from 0 to 65% of control richness. Using hierarchical structural equation modelling, we found greater species loss in communities with a lower soil cation exchange capacity, colder regional temperature, and larger production increase following N addition, independent of initial species richness, plant productivity, and the relative abundance of most plant functional groups. Our results indicate sensitivity to N addition is co-determined by environmental conditions and production responsiveness, which overwhelm the effects of initial community structure and composition. [ABSTRACT FROM AUTHOR]

The article discusses the effect of the gradual declination of the diversity of plant and animal life relative to human alterations of ecosystems. It also provides a deductive reasoning of the most crucial messages emerging from the most recent scientific literature. Further, it enunciates international appraisals and assessments of the role of biodiversity in ecosystem services and human well-being.

Spatial and temporal niche differentiation are potential mechanisms of plant species’ coexistence in many communities, including many grasslands. In a 6-year field experiment, a dominant prairie bunchgrass, Schizachyrium scoparium, excluded species sharing similar phenology and rooting depth, but coexisted with species differing in phenology and rooting depth. We used a series of experimental plots that differed in S. scoparium abundance to measure the effect of S. scoparium on abundances of other species and on soil nitrate concentrations across time and depth. Because we found that S. scoparium most strongly reduced soil nitrate levels at mid-season and at shallow depths, we hypothesized that at higher S. scoparium abundance, species with mid-season phenology and shallow roots would be excluded and that deep-rooted and early season species would be more likely to persist. As predicted, the proportional number and cover of species exploiting different niches than S. scoparium (early season and deep-rooted species) increased across the S. scoparium abundance gradient. This work provides novel empirical evidence for the factors that contribute to species coexistence in the field. Our study suggests that spatial and temporal niche differentiation promote species coexistence in these grasslands. [ABSTRACT FROM AUTHOR]

• Concentration reduction theory is the leading theory regarding the mechanism of competition for nutrients in soils among plants, yet it has not been rigorously tested.• Here we used a spatially explicit, fine-scale grid-based model that simulated diffusion and plant uptake of nutrients by plants in soil to test whether concentration reduction theory was appropriate for terrestrial plant competition for nutrients.• In the absence of competition, increasing the rate of diffusion allows a plant to maintain positive growth rates below the lowest average concentration to which it can reduce nutrients in soil solution (R*). As such, differences among plants in the reduction of soil moisture, which here primarily affects nutrient diffusion, can causeR* to predict competitive success incorrectly. The stronger competitor for nutrients captures the largest proportion of the nutrient supply by ensuring nutrients contact its roots before those of a competitor.• Although the metric derived from concentration reduction theory,R*, might have predictive power for competitive outcomes in terrestrial ecosystems, this evidence suggests that plants outcompete other plants for nutrients by pre-empting the supply, not reducing the average concentration.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01386.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]

Complementarity and sampling effects may both contribute to increased invasion resistance at higher diversity. We measured plant invader biomass across a long-term experimental plant diversity gradient. Invader species’ biomass was inhibited in more diverse plots, largely because of the presence of strongly competitive C4 bunchgrasses, consistent with a sampling effect. Invader biomass was negatively correlated with resident root biomass, and positively correlated with soil nitrate concentrations, suggesting that competition for nitrogen limited invader success. Resident root biomass increased and soil nitrate concentrations decreased with the presence of C4 grasses and also across the diversity gradient, suggesting that diverse plots are more competitive because of the presence of C4 grasses. In addition to this evidence for a sampling effect, we also found evidence for a complementarity effect. Specifically, the percentage of plots that had lower invader biomass than did the best resident monoculture (i.e. that had invader‘underyielding’) increased across the species richness gradient. This pattern cannot be explained by a sampling effect and is a unique signature of complementarity effects. Our results demonstrate the importance of multiple mechanisms by which diversity can increase invasion resistance. [ABSTRACT FROM AUTHOR]

A species-addition experiment showed that prairie grasslands have a structured, nonneutral assembly process in which resident species inhibit, via resource consumption, the establishment and growth of species with similar resource use patterns and in which the success of invaders decreases as diversity increases. In our experiment, species in each of four functional guilds were introduced, as seed, into 147 prairie-grassland plots that previously had been established and maintained to have different compositions and diversities. Established species most strongly inhibited introduced species from their own functional guild. Introduced species attained lower abundances when functionally similar species were abundant and when established species left lower levels of resources unconsumed, which occurred at lower species richness. Residents of the C4 grass functional guild, the dominant guild in nearby native grasslands, reduced the major limiting resource, soil nitrate, to the lowest levels in midsummer and exhibited the greatest inhibitory effect on introduced species. This simple mechanism of greater competitive inhibition of invaders that are similar to established abundant species could, in theory, explain many of the patterns observed in plant communities. [ABSTRACT FROM AUTHOR]

Abstract In an experiment that factorially manipulated plant diversity, CO2 , and N, we quantified the effects of the presence of species on assemblage biomass over 10 time points distributed over 5 years. Thirteen of the 16 species planted had statistically significant effects on aboveground and/or belowground biomass. Species differed dramatically in their effects on biomass without any relationship between aboveground and below-ground effects. Temporal complementarity among species in their effects seasonally, successionally, and in response to a dry summer maintained the diversity–biomass relationships over time and may be the cause behind higher diversity plots having less variation in biomass over time. The response of plant biomass to elevated N, but not CO2 , was at times entirely dependent on the presence of a single species. [ABSTRACT FROM AUTHOR]

This synthetic data set contains plant species relative abundance measures from 35 nitrogen (N) fertilization experiments conducted at 10 sites across North America. The data set encompasses the fertilization responses of 575 taxa from 1159 experimental plots. The methodology varied among experiments, in particular with regard to the type and amount of N added, plot size, species composition measure (biomass harvest, pin count, or percent cover), additional experimental manipulations, and experimental duration. At each site, each species has been classified according to a number of easily identified categorical functional traits, including life history, life form, the number of cotyledons, height relative to the canopy, potential for clonal growth, and nativity to the United States. Additional data are available for many sites, indicated by references to publications and web sites. Analyses of these data have shown that N enrichment significantly alters community composition in ways that are predictable on the basis of plant functional traits as well as environmental context. This data set could be used to answer a variety of questions about how plant community composition and structure respond to environmental changes. [ABSTRACT FROM AUTHOR]