Article

Alternative biomass strategies for bioenergy: Implications for bird communities across the southeastern United States

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Abstract

Concerns over energy demands and climate change has led the United States to set ambitious targets for bioenergy production in the coming decades. The southeastern U.S. has had a recent increase in biomass woody pellet production and is projected to produce a large portion of the nation's cellulosic biofuels. We conducted a large-scale, systematic comparison of potential impacts of two types of bioenergy feedstocks–corn (Zea mays) and pine (Pinus spp.)–on bird communities across the southeastern U.S. In addition, we evaluated three biomass alternatives for woody biomass from pine plantations: thinning, residue harvest, and short-rotation energy plantations (SREPs). We conducted transect counts for birds in eight different land-uses across the region (85 sites), including corn fields, reference and plantation forests, 2013-2015. We then used hierarchical occupancy models to test the effect of these biomass alternatives on 31 species. Across all species, birds had lower rates of occupancy in corn fields compared to pine stands. Thinning had positive effects on the average occupancy across species, while residue harvest and the potential conversion of conventional plantations to SREPs had negative effects. Cavity nesters and species with bark-gleaning foraging strategies tended to show the strongest responses. These results highlight the potential negative effects of corn as an energy crop relative to the use of pine biomass. In addition, harvesting biomass via thinning was a bird-friendly harvest method in comparison to other alternatives. While SREPs may negatively impact some bird species, previously reported yields emphasize that they may provide an order of magnitude greater yield per unit area than other alternatives considered, such that this land-use practice may be an important alternative to minimize the bioenergy impacts across the landscape. This article is protected by copyright. All rights reserved.

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... We sampled bees in 85 sites in the southeastern coastal plain of eastern Alabama, northern Florida, and southern Georgia (Fig. 1), an area with a substantial extent of pine plantations. Our sampling effort was part of a larger study which included sampling for birds (Gottlieb et al. 2017) as well as reptiles, amphibians, and bats. We sampled between April and July in three years, 2013-2015. ...
... These remnant ecosystems are managed to maintain some degree of the natural fire regime needed for maintenance of these systems (Christensen 2000). This study is part of a larger research project on pine biofuel production in the US (Gottlieb et al. 2017), and includes contrasts within plantation forest sites designed to compare forest management practices between biofuel feedstock and traditional timber production. A previous study emerging from this research project found no substantial differences in bee abundance, richness, and community composition among different management practices in standing plantations (Gruenewald 2014), so we have aggregated these sites. ...
... Lasioglossum is the single most speciose genus of bees on Earth, with more than 1250 described species (Michener 2000). They are primarily ground-nesting, though some species nest in rotting wood (Michener 2000); while the nesting habits of these particular species are not documented, they were common even in clearcuts with woody debris removed (about 50% of our clearcut sites; see Gottlieb et al. 2017), consistent with the idea that they are soil-nesting. The mechanical disturbance of tree harvesting in clearcuts also typically involves substantial soil and non-tree vegetation disturbance, which can open up more nesting sites. ...
Article
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Context Land-use change is a key driver of pollinator declines worldwide. Plantation forests are a major land use worldwide and are likely to expand substantially in the near term, especially with projected cellulosic biofuel production. But little is known about the potential local and landscape-scale impacts of plantation forestry on bees, the most important group of pollinators worldwide. Objectives We studied the effects of local management, landscape context, and their interaction on bee abundance and species richness in the southeastern US, in pine plantations and other nearby land uses. Methods We sampled bee communities using aerial netting and pan trapping in 85 sites over 3 years. Results We found that both landscape composition and configuration are important factors for bee diversity and abundance at the landscape scale, though interestingly many landscape factors showed contrasting directional responses for diversity versus abundance. Removing the four most common species, all in the genus Lasioglossum (and which comprised ~ 45% of all specimens) largely harmonized the results between diversity and abundance. In addition, we found several interactions between local management and landscape factors, all consistent with the idea that compositional heterogeneity and configurational complexity are more important for bee communities in poorer-quality local habitat. Conclusions Our results underscore the importance of considering (1) both landscape configuration and composition in analyses, and (2) interactions between local management and landscape factors. The interactions in particular highlight the need to maintain landscape compositional heterogeneity and configurational complexity, particularly in heavily managed landscapes.
... In particular, SRCs and reforestations seem to play an important role for some birds by providing them with complementary or supplementary habitat for foraging and nesting. 1997, Perttu 1998, Reddersen 2001, Berg 2002, Kleijn & Sutherland 2003, Anderson & Fergusson 2006, Sage et al. 2006, Gottlieb et al. 2017. In particular, avian abundance and species richness were consistently higher in SRCs than in row crop or smallgrain fields, especially in regions dominated by agriculture (Berg 2002, Sage et al. 2006. ...
... It has been suggested that SRCs are contributing to the decline in farmland bird populations, due to a reduction of landscape openness (Mourgaud 1996), even though the efficacy of arboriculture to benefit bird populations has been shown in agroecosystems (Berg 2002, Sage et al. 2006, Gottlieb et al. 2017. Half of the species found in the SRCs are farmland birds, which exceed both the forest and the generalist species in abundance and richness, which has also been shown elsewhere , Christian et al. 1998, Berg 2002, Sage et al. 2006, Riffell et al. 2011. ...
... As found by various authors, heterogeneity in agricultural landscapes is associated with higher species richness (Benton et al. 2003, Fuhlendorf et al. 2006, Laube et al. 2006. From this point of view SRCs and other tree plantations diversify the landscape, potentially attracting new species in intensively managed agricultural ecosystems and contributing to stabilizing the bird community (Devictor & Jiguet 2007, Gottlieb et al. 2017. From a management perspective it seems important to encourage a system with rotational harvesting of mixed age-class blocks which could enhance habitat quality , Sage 1998, Giordano & Meriggi 2009). ...
Article
In recent decades, the establishment of plantations to produce biomass for energy, known as short rotation coppice (SRC), has been increasing in many countries in Europe. As with other tree plantations, these stands could enhance the structural diversity of intensively managed farmlands and consequently lead to an increase in animal diversity. In this study, we examined the effects of hybrid poplar SRCs on breeding bird richness, diversity and abundance in Northern Italy. We recorded bird species and estimated their abundances using point counts. We then analysed the relationships between landscape composition and bird abundances, as well as community composition, using canonical correspondence analysis. The results showed that birds abundances in SRCs were generally lower than in woodland and arable land (SRC: 1.30 birds/km2, woodland: 2.57, arable land: 1.89), and the same was true for species richness (SRC: 7.06 species/km2, woodland: 12.90, arable land: 9.13) and species diversity (Shannon Indices in SRC: 0.951, woodland: 1.606, arable land: 1.241). Half of the species found in SRC are considered farmland birds, a group whose species richness was significantly higher than that of forest and generalist species. Our research suggests that a system with rotational harvesting of mixed age and structure stands enhances habitat heterogeneity and consequently could support bird communities. In particular, SRCs and reforestations seem to play an important role for some birds by providing them with complementary or supplementary habitat for foraging and nesting.
... Surveys were postponed if wind or rain compromised an observer's ability to detect birds. Additional details are in Gottlieb et al. (2017). ...
... Both scenarios showed the highest cumulative diversity, suggesting that over the course of a stand rotation, biomass harvesting generally leads to less diversity ( Figure 5). This is a novel result that we had not assessed previously (Gottlieb et al., 2017;Jones et al., 2020;Loy et al., 2020;Ober et al., 2020). Our landscape scenarios, focused on temporal accumulation of species richness, produced inferences about bioenergy effects to biodiversity that were not apparent in analyses of alpha and beta diversity. ...
... For example, short-rotation energy plantations are a highly intensive wood production system that maximize biomass produced for bioenergy but result in lower alpha and beta diversity (Figures 3 & 5). Although they are production intensive, a smaller spatial footprint (Heaton et al., 2008) is required to generate comparable amounts of biomass in shortrotation energy plantations relative to thinning and residue removal (Munsell & Fox, 2010;Gottlieb et al., 2017). This difference can be conceptualized in a land sparing and sharing framework (Fischer et al., 2008;Anderson-Teixeira et al., 2012), where resource extraction can be thought of as either extensive but low-impact or intensive but high-impact. ...
Article
Full-text available
International demand for wood and other forest products continues to grow rapidly, and uncertainties remain about how animal communities will respond to intensifying resource extraction associated with woody bioenergy production. We examined changes in alpha and beta diversity of bats, bees, birds, and reptiles across wood production landscapes in the southeastern United States, a biodiversity hotspot that is one of the principal sources of woody biomass globally. We sampled across a spatial gradient of paired forest land-uses (representing pre and postharvest) that allowed us to evaluate biological community changes resulting from several types of biomass harvest. Short-rotation practices and residue removal following clearcuts were associated with reduced alpha diversity (-14.1 and -13.9 species, respectively) and lower beta diversity (i.e., Jaccard dissimilarity) between land-use pairs (0.46 and 0.50, respectively), whereas midrotation thinning increased alpha (+3.5 species) and beta diversity (0.59). Over the course of a stand rotation in a single location, biomass harvesting generally led to less biodiversity. Cross-taxa responses to resource extraction were poorly predicted by alpha diversity: correlations in responses between taxonomic groups were highly variable (-0.2 to 0.4) with large uncertainties. In contrast, beta diversity patterns were highly consistent and predictable across taxa, where correlations in responses between taxonomic groups were all positive (0.05-0.4) with more narrow uncertainties. Beta diversity may, therefore, be a more reliable and information-rich indicator than alpha diversity in understanding animal community response to landscape change. Patterns in beta diversity were primarily driven by turnover instead of species loss or gain, indicating that wood extraction generates habitats that support different biological communities.
... We sampled bees in 85 sites in the southeastern coastal plain of eastern Alabama, northern Florida, and southern Georgia (Fig. 1), an area with a substantial extent of pine plantations. Our sampling effort was part of a larger study which included sampling for birds (Gottlieb et al. 2017) as well as reptiles, amphibians, and bats. We sampled between April and July in three years, 2013-2015. ...
... These remnant ecosystems are managed to maintain some degree of the natural fire regime needed for maintenance of these systems (Christensen 2000). This study is part of a larger research project on pine biofuel production in the US (Gottlieb et al. 2017), and includes contrasts within plantation forest sites designed to compare forest management practices between biofuel feedstock and traditional timber production. A previous study emerging from this research project found no substantial differences in bee abundance, richness, and community composition among different management practices in standing plantations (Gruenewald 2014), so we have aggregated these sites. ...
... Lasioglossum is the single most speciose genus of bees on Earth, with more than 1250 described species (Michener 2000). They are primarily ground-nesting, though some species nest in rotting wood (Michener 2000); while the nesting habits of these particular species are not documented, they were common even in clearcuts with woody debris removed (about 50% of our clearcut sites; see Gottlieb et al. 2017), consistent with the idea that they are soil-nesting. The mechanical disturbance of tree harvesting in clearcuts also typically involves substantial soil and non-tree vegetation disturbance, which can open up more nesting sites. ...
... In general, reduction of stand basal area, combined with a diversity of management practices applied periodically, provide some of the greatest increases in species richness and abundance (compared to un-thinned, unmanaged stands) within managed pine landscapes and provides managers with flexibility to manipulate stand conditions for multiple species. Comparisons among thinned, unthinned, and early successional managed pine stands generally suggest greater avian species richness and abundance in thinned stands [34,38,48,50,72,73]. ...
... An example of such a finefilter species is the red-cockaded woodpecker, which inhabits planted pine stands when specific management actions are taken (e.g., frequent fire, longer rotations, provision of artificial cavities, etc.). Bachman's sparrow and Henslow's sparrow are other examples of species that are readily maintained in managed pine landscapes if fine-filter management approaches are taken, such as thinning followed by frequent (e.g., 3-year fire return interval) prescribed fire or other hardwood control treatments (e.g., herbicide application alone or in combination with prescribed fire) [50,84,88,89,91]. Private forest landowners may intentionally manage areas to meet species' habitat requirements through mechanisms such as Safe Harbor Agreements to reduce or eliminate regulatory burdens across the broader landscape [92,93]. ...
... Though allowing snags to be retained, or allowing existing trees to senesce naturally may be contrary to yield objectives, it is plausible that a portion of timber growth could be dedicated to retention of deadwood to help meet sustainability objectives [105]. Empirical studies of avian community associations with CWD on southeastern managed pine stands also suggest that presence of CWD positively affects bird communities in early successional stands [46,47,50]. As such, removal of CWD during stand establishment may be detrimental to some avian communities. ...
Article
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The southeastern U.S. is widely known as a bastion of privately-owned, managed pine (Pinus spp.) forests, comprised primarily of native pine species. The region supports high levels of biodiversity, but also a multi-billion-dollar forest products economy critical to socioeconomic stability of rural areas. We conducted a systematic review of studies focused exclusively on avifaunal associations within privately-owned, managed pine landscapes in the southeastern U.S. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis framework to examine all available studies that evaluated aspects of avian diversity, abundance, and community composition across a suite of forest types, stand ages, and forest management practices within southeastern managed pine systems in the last 70 years. We screened 160 records through primary database searches, and 1696 secondary records from supplemental searches and other sources, and identified 103 relevant articles for inclusion. As expected, although there is no single forest management practice that best provides for avian communities, we found practices that: (1) involve prudent site preparation; (2) promote forest thinning and intermediate management practices; (3) provide non-pine vegetative cover; (4) supply fine- and meso-filter resources such as retained snags and coarse woody debris; and (5) promote heterogeneity in cover types, largely enhanced value of southeastern managed pine systems to avian communities. Overall, it appears that avian communities can be best maintained by providing a diverse mosaic of forest conditions in managed pine landscapes. Key research gaps include improving understanding avian population demographics, such as survival, reproduction, and dispersal.
... Several recent empirical studies examining one type of bioenergy harvesting (residue removal following clearcut harvest) suggest no consistent negative effects on vertebrate taxa (Fritts et al., 2016(Fritts et al., , 2015Grodsky et al., 2016bGrodsky et al., , 2016a). Yet few studies have compared and contrasted how different bioenergy harvesting alternatives related to increased bioenergy production (e.g., thinning, residue removal, shorter rotation times) may affect biodiversity in different ways (but see Gottlieb et al., 2017;Loy et al., 2020;Ober et al., 2020). ...
... Finally, larger sample sizes for the number of sites sampled within each landuse type would have increased statistical power and reduced uncertainty in parameter estimates; we may not have detected all potential effects due to low power. However, we have detected several meaningful effects in parallel studies of other taxa studied at the same sites examined here (e.g., Gottlieb et al. 2017, which suggests that the power might be sufficient to identify effects for some taxa. ...
... Our results suggest herpetofauna may respond in distinct ways to bioenergy intensification in the Southeast compared to other taxa, implying that diverse conservation strategies are needed in bioenergy landscapes. Whereas generally we found neutral to positive effects of residue removal following clearcuts on amphibian and reptile occupancy, respectively, Gottlieb et al. (2017) found relatively large negative responses by birds to residue removal on the same study area (but see Grodsky et al., 2016bGrodsky et al., , 2016a. In addition, Loy et al. (2020) examined bee community diversity in the same study area and found lower richness associated with residue removal. ...
Article
Bioenergy produced from woody biomass in managed forest systems represents a substantial portion of the global supply of renewable energy. As societies transition to renewable energy and demand for wood-based bioenergy increases, timber-producing forests and other agricultural and marginal lands may transition to bioenergy management regimes. Limited empirical information exists regarding how wildlife communities will respond to bioenergy intensification. We investigated herpetofaunal occurrence across 75 study sites located in two types of bioenergy feedstocks (corn and pine) to evaluate effects of bioenergy alternatives in a global biodiversity hotspot in the southeastern United States: the North American Coastal Plain. We found that removing harvest residue following clearcut management in pine forests as a source of woody biomass resulted in either neutral or positive effects for six of the seven herpetofaunal species examined. Other bioenergy alternatives, such as mid-rotation thinning and short-rotation practices, resulted in highly variable effects among individual species and generally contrasting effects between amphibians and reptiles. Similarly high variability was observed when comparing species occurrence patterns between corn and managed pine bioenergy feedstocks. Our study suggests herpetofaunal community responses to changing land-use practices in the era of bioenergy may be taxa- and species-specific. Some land-use practices (e.g., residue removal following clearcuts) may be generally compatible with conservation of most species examined, but conserving herpetofaunal diversity within the Southeast as bioenergy production increases may involve promoting heterogeneous managed landscapes in which a diversity of harvest approaches are used.
... Production of many of the so-called first-generation biofuel crops (e.g., corn ethanol) is expected to have greater environmental impacts than second-generation biofuel crops (e.g., pine), because the former require more intensive inputs, produce more greenhouse gases, and are grown in ways that offer low structural and compositional heterogeneity to wildlife (Fargione et al. 2009, Fletcher et al. 2011, Immerzeel et al. 2014. But, to date, few systematic comparisons of impacts to wildlife have been made across alternative biomass production pathways (but see Robertson et al. 2011, Gottlieb et al. 2017. Such comparisons could provide useful information for policy makers and practitioners in the bioenergy industry who must weigh environmental trade-offs related to the implementation of land management practices that produce bioenergy. ...
... Third, pine plantations in the Southeast are typically thinned (i.e., tree density is reduced for the first time commercially between ages 12 and 16 to promote growth of remaining trees; Antony et al. 2011, Amateis andCarlson 2014), and this harvested material is a potential source of biomass for bioenergy production. The energy yield obtained from each of these three biomass production pathways varies (Eisenbies et al. 2009, Munsell andFox 2010), and the nature of their impacts on biodiversity is presumed to vary as well (Verschuyl et al. 2011, Riffell et al. 2011a,b, Gottlieb et al. 2017, Loy et al. 2020, Nuñez-Regueiro et al. 2020. ...
... As part of a large investigation on bioenergy and biodiversity (Gottlieb et al. 2017, Miljanic et al. 2019, Loy et al. 2020, we collected bat occurrence and activity data from 84 study sites stratified across three broad geographic regions situated in the Southern Coastal Plains and Southeastern Plains ecoregions in the states of Alabama, Florida, and Georgia, USA (Fig. 1). We selected these regions because they are expected to play an important role in producing biomass for bioenergy production (USDA 2010, He et al. 2014. ...
Article
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Human demand for food, fiber, and space is accelerating the rate of change of land cover and land use. Much of the world now consists of a matrix of natural forests, managed forests, agricultural cropland, and urbanized plots. Expansion of domestic energy production efforts in the USA is one driver predicted to influence future land‐use and land management practices across large spatial scales. Favorable growing conditions make the southeastern USA an ideal location for producing a large portion of the country’s renewable bioenergy. We investigated patterns of bat occurrence in two bioenergy feedstocks commonly grown in this region (corn, Zea mays, and pine, Pinus taeda and P. elliottii). We also evaluated potential impacts of the three major pathways of woody biomass extraction (residue removal following clearcut harvest, short‐rotation energy plantations, and mid‐rotation forest thinning) to bat occurrence through a priori land‐use contrasts. We acoustically sampled bat vocalizations at 84 sites in the Southeastern Plains and Southern Coastal Plains of the southeastern USA across three years. We found that mid‐rotation thinning resulted in positive effects on bat occurrence, and potential conversion of unmanaged (reference) forest to managed forest for timber and/or bioenergy harvest resulted in negative effects on bat occurrence when effects were averaged across all species. The effects of short‐rotation energy plantations, removal of logging residues from plantation clearcuts, and corn were equivocal for all bat species examined. Our results suggest that accelerated production of biomass for energy production through either corn or intensively managed pine forests is not likely to have an adverse effect on bat communities, so long as existing older unmanaged forests are not converted to managed bioenergy or timber plantations. Beyond bioenergy crop production, mid‐rotation thinning of even‐aged pine stands intended for timber production, increases to the duration of plantation rotations to promote older forest stands, arranging forest stands and crop fields to maximize edge habitat, and maintaining unmanaged forests could benefit bat communities by augmenting roosting and foraging opportunities.
... To illustrate the use of combining data in distribution models, we link data from planned surveys on bird communities in managed forests across the southeastern United States with eBird data. The motivation for these planned surveys was to understand how variation in forest management impacts bird communities, with a focus on forest management practices being considered for bioenergy production (Gottlieb et al. 2017). Reliable estimates of bird occurrence were needed to understand effects of land-use change from bioenergy, which were investigated in detail in Gottlieb et al. (2017). ...
... The motivation for these planned surveys was to understand how variation in forest management impacts bird communities, with a focus on forest management practices being considered for bioenergy production (Gottlieb et al. 2017). Reliable estimates of bird occurrence were needed to understand effects of land-use change from bioenergy, which were investigated in detail in Gottlieb et al. (2017). However, there was also interest in making projections of potential effects across the region, given the potential for large-scale land-use changes arising from an increase in bioenergy in the southeastern United States (Galik and Abt 2016). ...
... However, there was also interest in making projections of potential effects across the region, given the potential for large-scale land-use changes arising from an increase in bioenergy in the southeastern United States (Galik and Abt 2016). Here, we focus on using these data to project species distributions across the region; see Gottlieb et al. (2017) for inferences on bioenergy. ...
Article
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Understanding and accurately modeling species distributions lies at the heart of many problems in ecology, evolution, and conservation. Multiple sources of data are increasingly available for modeling species distributions, such as data from citizen science programs, atlases, museums, and planned surveys. Yet reliably combining data sources can be challenging because data sources can vary considerably in their design, gradients covered, and potential sampling biases. We review, synthesize and illustrate recent developments in combining multiple sources of data for species distribution modeling. We identify five ways in which multiple sources of data are typically combined for modeling species distributions. These approaches vary in their ability to accommodate sampling design, bias, and uncertainty when quantifying environmental relationships in species distribution models. Many of the challenges for combining data are solved through the prudent use of integrated species distribution models: models that simultaneously combine different data sources on species locations to quantify environmental relationships for explaining species distribution. We illustrate these approaches using planned survey data on 24 species of birds coupled with opportunistically collected eBird data in the southeastern United States. This example illustrates some of the benefits of data integration, such as increased precision in environmental relationships, greater predictive accuracy, and accounting for sample bias. Yet it also illustrates challenges of combining data sources with vastly different sampling methodologies and amounts of data. We provide one solution to this challenge through the use of weighted joint likelihoods. Weighted joint likelihoods provide a means to emphasize data sources based on different criteria (e.g., sample size) and we find that weighting improves predictions for all species considered. We conclude by providing practical guidance on combining multiple sources of data for modeling species distributions. This article is protected by copyright. All rights reserved.
... Further, second-generation crops often come from otherwise unused sources of biomass, such as residues from forestry operations, or from prairies from which biomass harvest is often compatible with wildlife conservation (Fargione et al. , 2010Fletcher et al. 2011). Local studies along with regional and crop-specific meta-analyses have illustrated the potential impacts of bioenergy on biodiversity (e.g., Koh & Wilcove 2008;Fletcher et al. 2011;Verschuyl et al. 2011;Robertson et al. 2012;Werling et al. 2014;Gottlieb et al. 2017). However, currently, there has been no attempt to quantitatively synthesize these problems related to bioenergy and impacts on biodiversity across the planet (but see Immerzeel et al. 2014 for a qualitative global review). ...
... This approach has been used previously for interpreting effects of bioenergy alternatives (Meehan et al. 2010;Fletcher et al. 2011;Riffell et al. 2011). We pooled variation within crops (e.g., pine plantation ages), which can potentially mediate bioenergy impacts on biodiversity (e.g., Riffell et al. 2011;Gottlieb et al. 2017). Furthermore, some investigations did not contrast lands currently used for bioenergy production, but rather studied biodiversity in the major crops being considered for bioenergy that were producing other products at that time (e.g., timber and food [Fletcher et al. 2011]). ...
... First, sitespecific conditions can moderate the effects of potential bioenergy crops. For instance, favorable environmental conditions in pine plantations could have driven higher abundance and richness, especially for invasive species (Liu et al. 2012) and in well-managed plantations (e.g., Gottlieb et al. 2017). Heterogeneous landscapes with hedgerows or forest patches and ecological traits that allow some species to thrive in agriculture can explain high diversity and abundance in sugarcane, soybean, and corn (Nunes et al. 2006;Minor & Cianciolo 2007;Mulwa et al. 2012;Nuñez-Regueiro et al. 2015). ...
Article
Understanding how the world's flora and fauna will respond to bioenergy expansion is critical. This issue is particularly pronounced considering bioenergy's potential role as a driver of land-use change, the variety of production crops being considered and currently used for biomass, and the diversity of ecosystems that can potentially supply land for bioenergy across the planet. We conducted a global meta-analysis to ask how eight of the most commonly used bioenergy crops may impact site-level biodiversity. Species diversity and abundance were generally lower in crops being considered for bioenergy when compared to the natural ecosystems they may replace. First-generation crops, derived from oils, sugars, and starches, tended to have greater effects than second-generation crops, derived from lignocellulose, woody crops, or residues. Crop yield had non-linear effects on abundance and, to a lesser extent overall biodiversity, with biodiversity effects being driven by negative yield effects for birds but not other taxa. Our results emphasize that replacing natural ecosystems with bioenergy crops across the planet will largely be detrimental for biodiversity, with first generation and high yielding crops having the strongest negative effects. We argue that meeting energy goals with bioenergy using existing marginal lands or via biomass extraction within existing production landscapes may provide more biodiversity friendly alternatives than via land conversion of natural ecosystems. Impact Statement: Meta-analysis reveals that replacing natural ecosystems with bioenergy crops across the planet will largely be detrimental for biodiversity. This article is protected by copyright. All rights reserved.
... were lower in avian diversity, avian guild richness, and mammalian guild and species richness relative to unmanaged forest stands (i.e., not conventionally managed forest stands; Riffell, Verschuyl, Miller, & Wigley, 2011). However, Gottlieb et al. (2017) indicated that SRWC pine would support more bird species than maize fields but less than reference forest stands. ...
... Diversity of birds and mammals decreases in SRWC stands relative to longer rotation forestry and unmanaged forests, but less so than agriculture (Gottlieb et al., 2017;Riffell et al., 2011). However, in general there is a dearth of published literature on long-term effects of SRWCs at the stand scale or over the scale of mixed-used watersheds. ...
Article
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Logging and mill residues are currently the largest sources of woody biomass for bioenergy in the US, but short‐rotation woody crops (SRWCs) are expected to become a larger contributor to biomass production, primarily on lands marginal for food production. However, there are very few studies on the environmental effects of SRWCs, and most have been conducted at stand rather than at watershed scales. In this manuscript, we review the potential environmental effects of SRWCs relative to current forestry or agricultural practices and best management practices (BMPs) in the southeast US and identify priorities and constraints for monitoring and modeling these effects. Plot‐scale field studies and a watershed‐scale modeling study found improved water quality with SRWCs compared to agricultural crops. Further, a recent watershed‐scale experiment suggests that conventional forestry BMPs are sufficient to protect water quality from SRWC silvicultural activities, but the duration of these studies is short with respect to travel times of groundwater transporting nitrate to streams. While the effects of SRWC production on carbon
... Unfortunately, we were unable to include the impacts of intensification of existing management plantations in our analysis, because projections of intensification of existing plantations for the study region were not available, and the GAP habitat suitability models do not distinguish between different management intensities in pine plantations. Forest management can have either positive effects, for instance due to thinning (Gottlieb et al., 2017;Verschuyl et al., 2011), or neutral or negative impacts, for instance due to residue removal Gottlieb et al., 2017;Grodsky, Moorman, Fritts, & Hazel, et al., 2016;Riffell et al., 2011b) on species richness. Therefore, impacts on species richness due to pine plantation establishment may be overestimated if new plantations are not managed intensively. ...
... Unfortunately, we were unable to include the impacts of intensification of existing management plantations in our analysis, because projections of intensification of existing plantations for the study region were not available, and the GAP habitat suitability models do not distinguish between different management intensities in pine plantations. Forest management can have either positive effects, for instance due to thinning (Gottlieb et al., 2017;Verschuyl et al., 2011), or neutral or negative impacts, for instance due to residue removal Gottlieb et al., 2017;Grodsky, Moorman, Fritts, & Hazel, et al., 2016;Riffell et al., 2011b) on species richness. Therefore, impacts on species richness due to pine plantation establishment may be overestimated if new plantations are not managed intensively. ...
Article
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Increasing wood pellet exports from the United States are projected to lead to changes in land use and timberland management, including a shift from natural timberland to pine plantations. These projected changes may impact biodiversity. This study aims to quantify potential biodiversity impacts of increased wood pellet demand in the southeastern US in a spatially explicit manner. We determined differences according to an index of potential species richness (for total, threatened and endemic species and four taxonomic groups) between scenarios of high and low demand for wood pellets, while taking into account potential developments in other wood markets and other land uses. Increased demand for wood pellets was projected to cause both positive and negative biodiversity impacts. Negative shifts in total potential species richness were projected for areas in Florida, coastal Virginia and North Carolina, and parts of the Gulf Coast. Positive shifts in total potential species richness were projected in parts of Oklahoma and Arkansas. In some locations, the direction of change differed per taxonomic group, highlighting the importance of analysing different taxonomic groups. Shifts in potential species richness due to increased wood pellet demand were considerably smaller compared to the changes due to other drivers, such as urbanization and increased timber demand. Biodiversity impacts due to wood pellet demand should therefore be considered in the context of other drivers of land‐use change and biodiversity loss. Our results provide information that allows policy makers, industry and NGOs to focus on areas of concern and take appropriate mitigation measures to limit negative biodiversity impacts and promote positive impacts. The spatially explicit approach presented in this study can be applied to different regions and drivers of land‐use change, to show how projected demand for an internationally traded commodity may lead to impacts on land use and biodiversity in the procurement region.
... Most existing studies evaluate the carbon benefits of electricity generated from imported industrial wood pellets from the southern United States [17,18] or biodiversity [19,20]. Existing studies focusing on the hydrological impacts of bioenergy feedstocks in the southern United States analyze mostly agriculture-based bioenergy feedstocks [21,22]. ...
... Therefore, the goal of this study is to assess the potential impacts of changing land use and climate on the hydrology, in general, and streamflow in particular, of a local watershed in the context of rising demand for industrial wood pellets in the southeastern United States. We hope that our results will help in developing a comprehensive understanding of the overall sustainability of the transatlantic wood pellet trade by bringing a fresh perspective of hydrology into consideration, apart from existing studies on carbon [17,18] and biodiversity [19,20]. ...
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This study examines the impact of projected land use changes in the context of growing production of industrial wood pellets coupled with expected changes in precipitation and temperature due to the changing climate on streamflow in a watershed located in the northeastern corner of the Oconee River Basin. We used the Soil and Water Assessment Tool (SWAT) for ascertaining any changes in streamflow over time. The developed model was calibrated over a seven-year period (2001–2007) and validated over another seven-year period (2008–2014). Any changes in streamflow were simulated for a combination of 10 land use and climate change cases, from 2015 to 2028, under the two scenarios of High and Low Demand for industrial wood pellets. Our results suggest that streamflow is relatively stable (<1% change) for land use and temperature-related cases relative to the base case of no change in land use and climate. However, changes in precipitation by ±10% lead to considerable changes (±25%) in streamflow relative to the base case. Based on our results, expected changes in precipitation due to the changing climate will determine any changes in the streamflow, rather than projected land use changes in the context of rising demand for industrial wood pellets for export purposes in the selected watershed, keeping land under urban areas as constant. This study contributes to our broader understanding of the sustainability of the transatlantic industrial wood pellet trade; however, we suggest undertaking similar research at a larger spatial scale over a longer time horizon for understanding trade-offs across carbon, biodiversity, and water impacts of the transatlantic industrial wood pellet trade.
... Shown is an example where the real world is conceptualized based on (a) the island model, (b) the patch-corridor-matrix model, (c) the landscape mosaic model, (d) the habitat variegation model, and (e) the continuum model that there are different types of patches from various cover types, such that it de-emphasizes a single focal habitat or cover type. For instance, different types of natural land cover (e.g., forest and wetland), agricultural land uses, and urban areas may all be simultaneously considered (Fahrig et al. 2011;Gottlieb et al. 2017). This conceptual model is now often used in a variety of conservation settings, particularly in situations where multiple objectives for land use and conservation are considered (Polasky et al. 2008;Phalan et al. 2011). ...
... For mapping we may want to label the integers based on the land- The landscape being considered. Shown is the reclassified National Land Cover Database for a 4 Â 4 km landscape in Alabama, which was sampled in Gottlieb et al. (2017) cover type classifications. We can provide labels and plot the map. ...
Chapter
Understanding spatial and temporal variation in land use and land cover is a topic that bridges a variety of disciplines such as ecology, geography, sociology, and economics. Land-use and land-cover change has major impacts on biodiversity and ecosystem services. Our goals are to introduce key concepts regarding land-use and land-cover change and provide insight on the quantification of such change. We first discuss some foundational concepts and terms that capture key aspects of land-use and land-cover change, including conceptual models that have been advanced and problems of habitat loss, fragmentation, and degradation, such as the patch-corridor-matrix, habitat variegation, and continuum models. We then provide an overview on common ways in which spatial patterns are quantified, focusing primarily on the quantification of variation in composition and configuration of land use and land cover at different spatial scales, such as pattern that arises at the patch, neighborhood, and entire landscape scales. We illustrate then how spatial patterns can be quantified at different scales using an example from the southeastern USA. Our example highlights the ways in which this variation in pattern can capture different components of landscapes considered to be important for biodiversity, such as habitat edge and isolation, and that many of the ways in which spatial pattern of land use and land cover are quantified are highly correlated. We end by illustrating the use of neutral landscape models, which have been used in both theoretical and applied problems for understanding patterns of land use and land cover.
... With the consideration of multiple system objectives, one practice may benefit some but not all landowner-valued ecosystem services, although a preferable balance may be achieved across multiple services. For example, empirically driven biodiversity metrics for certain taxa are shown to be higher under thinning but lower under clear-cut conditions in bioenergy pine plantation systems (Gottlieb et al., 2017;Loy et al., 2020;Jones et al., 2022). ...
... The 48 watersheds in the coastal plains of Alabama, Georgia, and Florida ( Figure S1) that we examined represent the study region of previous related work that investigated bioenergy effects on a variety of ecosystem services (Gottlieb et al., 2017;Jones et al., 2020;Loy et al., 2020;Ober et al., 2020;Jones et al. 2022). The watershed areas ranged from 696 to 7,374 km 2 , with a mean of 3,158 km 2 . ...
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Changes in global bioenergy consumption have catalyzed the emergence of forest plantations as an important energy alternative. In the southeastern United States, land cover changes caused by increasing demands for pine trees as a bioenergy feedstock incite associated impacts on local ecosystem services (e.g., water yield). However, water yield impacts from pine plantation management strategies, such as thinning and short rotation, have yet to be simultaneously examined on multiple spatial scales. Here, we modeled the effects of thinning and clear-cut conditions on long term mean annual water yield across a 55-year time horizon at the watershed scale (watershed area ranging 696 – 7,374 km²) in northern Florida, southern Georgia, and southern Alabama. Additionally, we assessed the long term water yield effects of thinning, clear-cut, and short-rotation management at the pine plantation (i.e., plot) scale. We compared three plot-level evapotranspiration models as well as the watershed-level Water Supply Stress Index water balance model to simulate plot and watershed hydrologic responses from pine plantation management scenarios. Both methods showed that 10% thinning had the smallest increase in water yield (<6%), while clear-cut conditions imposed the greatest increase (up to 51% for plot scale and up to 25% for watershed scale simulations). Short-rotation management caused plot-level water yield increases ranging from 3% to 24%. Overall, greater water yield effects were seen in site simulations, rather than in watersheds, reinforcing the importance of scale when assessing water budget impacts given land cover changes. These results suggest that landowners have agency over the magnitude of water that is yielded from their plantations and that local water supply shortages can be mitigated by changing forestry biomass management strategies. The opportunity to supplement local water availability is especially valuable within the context of changing climate cycles that may bring about drier local conditions. The multi-scale approach presented here can support efforts from landowners and water managers to optimize profit as well as ecosystem service provision.
... With the consideration of multiple system objectives, one practice may benefit some but not all landowner-valued ecosystem services, although a preferable balance may be achieved across multiple services. For example, empirically driven biodiversity metrics for certain taxa are shown to be higher under thinning but lower under clear-cut conditions in bioenergy pine plantation systems (Gottlieb et al., 2017;Loy et al., 2020;Jones et al., 2022). ...
... The 48 watersheds in the coastal plains of Alabama, Georgia, and Florida ( Figure S1) that we examined represent the study region of previous related work that investigated bioenergy effects on a variety of ecosystem services (Gottlieb et al., 2017;Jones et al., 2020;Loy et al., 2020;Ober et al., 2020;Jones et al. 2022). The watershed areas ranged from 696 to 7,374 km 2 , with a mean of 3,158 km 2 . ...
... Of all the species types, invertebrates exhibited the strongest statistical responses to residue quantities, and Grodsky et al. (2018) suggest that at least 15% retention of woody debris is a good conservation guideline for invertebrates. Gottlieb et al. (2017) conducted a survey of bird responses to biomass procurement for bioenergy in the SE USA across 31 bird species and three breeding seasons. The team took measurements at 85 sites throughout Florida, Georgia, and Alabama including corn fields, plantation forests for timber harvest, plantation forests for short rotation woody crops, and longleaf pine (Pinus palustris) forests (considered to be the reference forests). ...
Article
Land‐management choices made for economic and societal gains intrinsically influence landscapes and species that are dependent upon them. We propose a simple analysis framework to examine critical intersections between land‐management choices and the life‐history conditions of selected species of concern, thereby facilitating the identification of mitigation practices that can reduce negative impacts on species at risk. We test the proposed framework through application to gopher tortoise (Gopherus polyphemus ), a keystone species that is the focus of conservation efforts across the southeastern region of United States of America, where wood pellets are being produced for bioenergy. Production of these wood pellets for export to Europe and Asia has drastically increased in the past decade, raising concerns about potential harm to biodiversity since many species in the forests sourcing pellet production were already at risk prior to the development of this new commodity. Identifying the mechanisms of potential impacts of wood pellet production on species of concern is essential to establishing meaningful management recommendations that can enhance conservation efforts while supporting sustainable bioenergy. By considering the intersections between life‐history conditions of gopher tortoise and forest‐management practices related to woody biomass extraction for pellet production, we identify several mechanisms by which the wood‐pellet industry might affect this species of concern, both positively and negatively. We then identify mitigation practices that can help offset the potential impacts of logging, thinning, and dead wood removal on gopher tortoise. Our analysis framework may be transferable to other species of concern and land‐management practices across diverse landscapes. This article is categorized under: • Bioenergy > Economics and Policy • Bioenergy > Climate and Environment
... We used a stratified semi-random selection approach to locate 36 study sites spread across three study regions in the southeastern US, a region with a high prevalence of agriculture and timber production that is experiencing high rates of land use change (Napton et al., 2010). These three study regions spanned southern Alabama, southern Georgia, and north-central Florida, sampled as part of a larger study (Gottlieb et al., 2017;Ober et al., 2020) (Fig. 1). We placed a grid with 3 km x 3 km cells across each study region and classified land cover within each grid cell by simplifying the USGS EROS National Land Cover Data (US Geological Survey, 2014) land cover types into three categories: Forested, Field, and Other. ...
Article
As generalist predators, insectivorous bats exploit fluctuations in prey distribution and abundance. A more nuanced understanding of the influence of bats on arthropod pests requires documentation of the pest species bats consume and of the conditions associated with variation in rates of pest consumption. Here, we used high-throughput metabarcoding of DNA extracted from bat feces to investigate diets of 180 bats representing three Vespertilionidae species common to the southeastern US, a region dominated by agriculture and pine plantations. We detected 23 species of agricultural pests in bat diets, including pests responsible for severe economic damage, such as Helicoverpa zea, Spodoptera frugiperda, Chloridea virescens and Chrysodeixis includens. Incidence of pest consumption was high: 61% of all bats had consumed at least one agricultural pest species, with each bat consuming an average of 1.7 pest species. The likelihood of consumption of pests to row crops and the average size of pests consumed varied by bat species, with a large foliage-roosting species (Lasiurus seminolus) consuming a greater variety of pest species and pest species larger in size than smaller crevice, cavity, and cave roosting bat species (Nycticeus humeralis, Myotis austroriparius). Likelihood of pest consumption also varied among sampling periods (season) and among bats of different sizes (as reflected by wing length and mass). Overall, likelihood of pest consumption was higher in the late summer season than during spring or early summer, and higher among larger bats than smaller bats. Bat characteristics and seasonality were generally more effective than geographic features and weather conditions in predicting pest consumption patterns. Strategies for enhancing pest consumption services by bats in agroecosystems should strive to maintain and enhance diverse bat populations on a landscape scale by protecting and augmenting roost structures appropriate for each species. Our finding of widespread pest consumption by bats contributes to mounting evidence worldwide of the important role bats play in agricultural systems and highlights the value of incorporating bat conservation into integrated pest management programs globally.
... Our research focused on private timberlands in the key wood-based bioenergy states of Alabama, Georgia, and Florida (Gottlieb et al., 2017;United States Department of Agriculture, 2010). The Southern Coastal Plains and Southeastern Plains ecoregions include high concentrationws of private pine plantations (Zhang & Polyakov, 2010) that are used to produce wood products, including saw logs, veneer logs, pulpwood, composite panels, and wood pellets (Costanza et al., 2017;U.S. ...
Article
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International demand for wood‐based biomass for bioenergy production is growing, and private forestlands in the southeastern United States have the potential to supply that demand. The southeastern United States (Southeast) is the world’s largest exporter of wood pellets for bioenergy, primarily to the United Kingdom (UK) and the European Union (EU). However, wood‐based biomass production accounts for only a small share of total wood removals from private forestlands in the Southeast. There is sufficient wood‐based biomass in the Southeast to support greater production of wood pellets for domestic and international markets without redirecting timber from sawtimber and pulpwood production. In 2018‐19, we conducted 39 semi‐structured interviews with private forest landowners, foresters, loggers, and biomass production facility managers in Alabama, Florida, and Georgia to obtain their views on wood‐based biomass production in the Southeast. Although landowners were interested in supplying wood for biomass as a byproduct of timber harvesting, they seldom participated in wood‐based biomass production because of limited and unreliable access to biomass markets. Loggers and production facility managers had not invested in biomass production because they remain skeptical about the financial viability of wood‐based biomass. Continued obstacles to biomass production include: price competition with fossil fuels and conventional wood products; inconsistent domestic government support for biomass production; concerns about meeting the sustainability requirements to export wood‐based biomass to the UK and EU; and the high costs associated with harvesting low‐grade wood for biomass. The barriers to biomass expansion in the southeastern United States remain primarily economic and political rather than biophysical.
... I en tysk fältstudie visades att de flesta fågelarterna i odlingslandskapet föredrar trädor och andra gräsmarker framför majsodlingar (Hötker et al. 2009 I USA har fler studier genomförts, och det generella resultatet är att majs hyser färre arter och fågelindivider än de flesta perenna gräsmarker, som vall, betesmark, bioenergiodlingar med jungfruhirs och återskapad eller naturlig prärie (Fletcher et al. 2011, Rupp et al. 2012. Även jämfört med energiskogar av poppel och tall är majs klart sämre för fåglarna (Gottlieb et al. 2017). Framförallt saknas naturvårdsintressanta arter i majsodlingar (Blank et al. 2014). ...
Chapter
All topics in ecology and conservation play out in space and time at multiple scales. These scales describe the spatiotemporal dimensions of patterns or processes. By understanding and quantifying spatial scale, it can profoundly influence our understanding of ecological patterns and processes, and it can alter conservation decisions. Scale has two primary components, grain and extent, and it can be applied to describe ecological phenomena, ecological sampling, or data analysis. Spatial scale has been shown to be important for ecological and conservation problems because ecological processes can operate at different scales and patterns can be fundamentally different depending on the scale at which they are quantified. Two general approaches to the problem of scale include multiscale and multilevel modeling. Multiscale modeling quantifies environment conditions at multiple scales by altering either the grain or extent of the analysis, and then evaluates which of the considered scales best explains a pattern or process. In multilevel modeling, the focus is on interpreting effects at different levels in an organizational hierarchy. We illustrate the use of buffer-based and kernel-based multiscale modeling of species–environment relationships using an example of reptile distribution (i.e., the southeastern five-lined skink, Plestiodon inexpectatus) in the Southeastern USA. Our example shows how to optimally identify the scale at which species respond to the environment but also illustrates how the quantification of pattern is highly correlated across scales, a common issue in multiscale modeling. We end by discussing some further advances in understanding and quantifying scale.
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1.Cultivation of bioenergy feedstocks is a growing land‐use worldwide, yet we have a poor understanding of how bioenergy crop management practices affect biodiversity. This knowledge gap is particularly acute for candidate cellulosic bioenergy feedstocks, such as tree plantations, and for organisms that provide important ecosystem services, such as pollinators. 2.We examined bee communities in 83 sites across three states in the southeastern USA—Alabama, Florida and Georgia. We compared bee abundance and diversity in 66 pine plantation sites that reflect management with and without potential bioenergy feedstock production. At least three bioenergy feedstock production methods have been proposed for this region: 1) converting conventional timber stands to short‐rotation bioenergy plantations; 2) harvesting feedstock by thinning conventional plantations; and 3) harvesting of woody debris residues after plantations have been clear‐cut. 3.We found that bioenergy‐associated management practices including younger plantations (relative to older) and woody debris removal (relative to debris unremoved) in clear‐cut plantations were associated with reduced bee diversity. Removing ground debris in clear‐cut plantations also drastically increased bee abundance, though this effect was largely driven by strong dominance of just two bee species. Clear‐cut plantations had lower beta diversity than standing plantations. 4.Synthesis and applications. Management practices associated with bioenergy feedstock production can have negative effects on bee community diversity. In particular, harvesting of debris in clear‐cut plantations dramatically reduces bee diversity. Large‐scale bioenergy feedstock production that increases the prevalence of young and clear‐cut stands may cause landscape‐level beta diversity to decline. Nevertheless, bioenergy pine plantations likely support higher bee diversity than corn fields, an alternative bioenergy feedstock.
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Forests in the southeastern USA have been actively managed for timber and other wood products for over 200 years. The wood pellet industry is relatively new and has generated polarised debate between those who want little or no active management of forests in the region, and those who point to the region’s long history of sustainable forest management (broadly a debate between those seeking to protect nature from use and proponents of production forestry). Outside plantations grown for the purpose, the wood pellet industry claims to use thinnings and forest residues from final timber harvests (as well as sawmill residues), logging waste and material from forests harvested for timber. Claims that the industry uses material from the forest that would otherwise have no market and that this is a co-product of harvests that would happen in any case have been contested and assertions made about the damage the industry is doing to forests in the region. The academic literature on specific impacts of the wood pellet industry on the ecology of southeastern forests is sparse. In order to determine likely impacts of the industry, an assessment was made of the broader impacts of harvest and extraction techniques which remove residues generally. The impact of such forest management techniques on terrestrial and aquatic biodiversity has not been systematically assessed, despite the large volume of literature over several decades. A systematic synthesis of the literature was therefore conducted to create an evidence base of knowledge of relevance to future policy and practice. The synthesis followed best practice guidelines on conducting systematic synthesis. In addition to a searchable database of relevant research, an interactive cartographic map was produced which enables users to interrogate the evidence base according to criteria defined in the format of the evidence data sheets created for each study. In total 19,919 articles were assessed systematically, from which 211 studies were identified and analysed in detail. The majority of studies (145) in the evidence base report no negative impacts of forestry practices on biodiversity (i.e. 69% of the studies). The review covers in detail the subset of papers that do report negative impacts and these can also be filtered and interrogated separately on the systematic map. The analysis shows that within this small subset of studies, impacts appear to be greatest for land invertebrates (26% of all negative impacts, i.e. 8% of all studies).
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The ongoing debate about costs and benefits of wood-pellet based bioenergy production in the southeastern United States (SE US) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, “How is the production of wood pellets in the SE US affecting forest systems and the ecosystem services they provide?” To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE US are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically-based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to non-forest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long-term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
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Forest regeneration following timber harvest is a principal source of habitat for early-successional birds and characterized by influxes of early-successional vegetation and residual downed woody material. Early-successional birds may use harvest residues for communication, cover, foraging, and nesting. Yet, increased market viability of woody biomass as bioenergy feedstock may intensify harvest residue removal. Our objectives were to: 1) evaluate effects of varying intensities of woody biomass harvest on the early-successional bird community; and (2) document early-successional bird use of harvest residues in regenerating stands. We spot-mapped birds from 15 April– 15 July, 2012–2014, in six woody biomass removal treatments within regenerating stands in North Carolina (n = 4) and Georgia (n = 4), USA. Treatments included clearcut harvest followed by: (1) traditional woody biomass harvest with no specific retention target; (2) 15% retention with harvest residues dispersed; (3) 15% retention with harvest residues clustered; (4) 30% retention with harvest residues dispersed; (5) 30% retention with harvest residues clustered; and (6) no woody biomass harvest (i.e., reference site). We tested for treatment-level effects on breeding bird species diversity and richness, early-successional focal species territory density (combined and individual species), counts of breeding birds detected near, in, or on branches of harvest piles/windrows, counts of breeding bird behaviors, and vegetation composition and structure. Pooled across three breeding seasons, we delineated 536 and 654 territories and detected 2,489 and 4,204 birds in the North Carolina and Georgia treatments, respectively. Woody biomass harvest had limited or short-lived effects on the early-successional, breeding bird community. The successional trajectory of vegetation structure, rather than availability of harvest residues, primarily drove avian use of regenerating stands. However, many breeding bird species used downed wood in addition to vegetation, indicating that harvest residues initially may provide food and cover resources for early-successional birds in regenerating stands prior to vegetation regrowth.
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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.
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Production of woody biomass for bioenergy, whether wood pellets or liquid biofuels, has the potential to cause substantial landscape change and concomitant effects on forest ecosystems, but the landscape effects of alternative production scenarios have not been fully assessed. We simulated landscape change from 2010 to 2050 under five scenarios of woody biomass production for wood pellets and liquid biofuels in North Carolina, in the southeastern United States, a region that is a substantial producer of wood biomass for bioenergy and contains high biodiversity. Modeled scenarios varied biomass feedstocks, incorporating harvest of ‘conventional’ forests, which include naturally regenerating as well as planted forests that exist on the landscape even without bioenergy production, as well as purpose-grown woody crops grown on marginal lands. Results reveal trade-offs among scenarios in terms of overall forest area and the characteristics of the remaining forest in 2050. Meeting demand for biomass from conventional forests resulted in more total forest land compared with a baseline, business-as-usual scenario. However, the remaining forest was composed of more intensively managed forest and less of the bottomland hardwood and longleaf pine habitats that support biodiversity. Converting marginal forest to purpose-grown crops reduced forest area, but the remaining forest contained more of the critical habitats for biodiversity. Conversion of marginal agricultural lands to purpose-grown crops resulted in smaller differences from the baseline scenario in terms of forest area and the characteristics of remaining forest habitats. Each scenario affected the dominant type of land-use change in some regions, especially in the coastal plain that harbors high levels of biodiversity. Our results demonstrate the complex landscape effects of alternative bioenergy scenarios, highlight that the regions most likely to be affected by bioenergy production are also critical for biodiversity, and point to the challenges associated with evaluating bioenergy sustainability.
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Domestic and foreign renewable energy targets and financial incentives have increased demand for woody bio- mass and bioenergy in the southeastern United States. This demand is expected to be met through purpose- grown agricultural bioenergy crops, short-rotation tree plantations, thinning and harvest of planted and natural forests, and forest harvest residues. With results from a forest economics model, spatially explicit state-and-tran- sition simulation models, and species-habitat models, we projected change in habitat amount for 16 wildlife spe- cies caused by meeting a renewable fuel target and expected demand for wood pellets in North Carolina, USA. We projected changes over 40 years under a baseline ‘business-as-usual’ scenario without bioenergy production and five scenarios with unique feedstock portfolios. Bioenergy demand had potential to influence trends in habi- tat availability for some species in our study area. We found variation in impacts among species, and no sce- nario was the ‘best’ or ‘worst’ across all species. Our models projected that shrub-associated species would gain habitat under some scenarios because of increases in the amount of regenerating forests on the landscape, while species restricted to mature forests would lose habitat. Some forest species could also lose habitat from the con- version of forests on marginal soils to purpose-grown feedstocks. The conversion of agricultural lands on mar- ginal soils to purpose-grown feedstocks increased habitat losses for one species with strong associations with pasture, which is being lost to urbanization in our study region. Our results indicate that landscape-scale impacts on wildlife habitat will vary among species and depend upon the bioenergy feedstock portfolio. There- fore, decisions about bioenergy and wildlife will likely involve trade-offs among wildlife species, and the choice of focal species is likely to affect the results of landscape-scale assessments. We offer general principals to con- sider when crafting lists of focal species for bioenergy impact assessments at the landscape scale.
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Forests are a major supplier of renewable energy; however, gleaning logging residues for use as woody biomass feedstock could negatively alter habitat for species dependent on downed wood. Biomass Harvesting Guidelines (BHGs) recommend retaining a portion of woody biomass on the forest floor following harvest. Despite BHGs being developed to help ensure ecological sustainability, their contribution to biodiversity has not been evaluated experimentally at operational scales. We compared herpetofauanal evenness, diversity, and richness and abundance of Anaxyrus terrestris and Gastrophryne carolinensis among six treatments that varied in volume and spatial arrangement of woody biomass retained after clearcutting loblolly pine (Pinus taeda) plantations in North Carolina, USA (n = 4), 2011-2014 and Georgia (n = 4), USA 2011-2013. Treatments were: (1) biomass harvest with no BHGs, (2) 15% retention with biomass clustered, (3) 15% retention with biomass dispersed, (4) 30% retention with biomass clustered, (5) 30% retention with biomass dispersed, and (6) no biomass harvest. We captured individuals with drift fence arrays and compared evenness, diversity, and richness metrics among treatments with repeated-measure, linear mixed-effects models. We determined predictors of A. terrestris and G. carolinensis abundances using a priori candidate N-mixture models with woody biomass volume, vegetation structure, and groundcover composition as covariates. We had 206 captures of 25 reptile species and 8710 captures of 17 amphibian species during 53 690 trap nights. Herpetofauna diversity, evenness, and richness were similar among treatments. A. terrestris abundance was negatively related to volume of retained woody biomass in treatment units in North Carolina in 2013. G. carolinensis abundance was positively related with volume of retained woody debris in treatment units in Georgia in 2012. Other relationships between A. terrestris and G. carolinensis abundances and habitat metrics were weak or absent. The lack of consistent community or population responses suggests the addition of a woody biomass harvest to a clearcut in pine plantations does not impact herpetofauna use of Coastal Plain loblolly plantations in the southeastern United States. We recommend additional research to examine relationships between woody biomass harvesting and rarer species or amphibians with high desiccation risk, particularly in other regions and harvesting systems.
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Forests are a major supplier of renewable energy; however, gleaning logging residues for use as woody biomass feedstock could negatively alter habitat for species dependent on downed wood. Biomass Harvesting Guidelines (BHGs) recommend retaining a portion of woody biomass on the forest floor following harvest. Despite BHGs being developed to help ensure ecological sustainability, their contribution to biodiversity has not been evaluated experimentally at operational scales. We compared herpetofauanal evenness, diversity, and richness and abundance of Anaxyrus terrestris and Gastrophryne carolinensis among six treatments that varied in volume and spatial arrangement of woody biomass retained after clearcutting loblolly pine (Pinus taeda) plantations in North Carolina, USA (n = 4), 2011–2014 and Georgia (n = 4), USA 2011–2013. Treatments were: (1) biomass harvest with no BHGs, (2) 15% retention with biomass clustered, (3) 15% retention with biomass dispersed, (4) 30% retention with biomass clustered, (5) 30% retention with biomass dispersed, and (6) no biomass harvest. We captured individuals with drift fence arrays and compared evenness, diversity, and richness metrics among treatments with repeated-measure, linear mixed-effects models. We determined predictors of A. terrestris and G. carolinensis abundances using a priori candidate N-mixture models with woody biomass volume, vegetation structure, and groundcover composition as covariates. We had 206 captures of 25 reptile species and 8710 captures of 17 amphibian species during 53 690 trap nights. Herpetofauna diversity, evenness, and richness were similar among treatments. A. terrestris abundance was negatively related to volume of retained woody biomass in treatment units in North Carolina in 2013. G. carolinensis abundance was positively related with volume of retained woody debris in treatment units in Georgia in 2012. Other relationships between A. terrestris and G. carolinensis abundances and habitat metrics were weak or absent. The lack of consistent community or population responses suggests the addition of a woody biomass harvest to a clearcut in pine plantations does not impact herpetofauna use of Coastal Plain loblolly plantations in the southeastern United States. We recommend additional research to examine relationships between woody biomass harvesting and rarer species or amphibians with high desiccation risk, particularly in other regions and harvesting systems.
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Woody biomass from the southeast United States is expected to play an important role in meeting European Union renewable energy targets. In crafting policies to guide bioenergy development and in guiding investment decisions to meet established policy goals, a firm understanding of the interaction between policy targets and forest biomass markets is necessary, as is the effect that this interaction will have on environmental and economic objectives. This analysis increases our understanding of these interactions by modeling the response of southern US forest markets to new pellet demand in the presence of sustainability sourcing or harvest criteria. We first assess the influence of EU recommended sustainability guidelines on the forest inventory available to supply EU markets, and then model changes in forest composition and extent in response to expected increases in pellet demand. Next, we assess how sustainability guidelines can influence the evolution of forest markets in the region, paying particular attention to changes in land use and forest carbon. Regardless of whether sustainability guidelines are applied, we find increased removals, an increase in forest area, and little change in forest inventory. We also find annual gains in forest carbon in most years of the analysis. The incremental effect of sustainability guideline application on forest carbon and pellet greenhouse gas (GHG) balance is difficult to discern, but results suggest that guidelines could be steering production away from sensitive forest types inherently less responsive to changing market conditions. Pellet GHG balance shows significant annual change and is attributable to the complexity of the underlying forest landscape. The manner by which GHG balance is tracked is thus a critical policy decision, reinforcing the importance and relevance of current efforts to develop approaches to accurately account for the GHG implications of biomass use both in the United States and European Union.
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Abstract Supply chain and delivered cost models for seven feedstocks (loblolly pine, Eucalyptus, natural hardwood, switchgrass, Miscanthus, sweet sorghum, and corn stover) were built, simulating a supply of 453,597 dry tons per year to a biorefinery. Delivered cost of forest-based feedstocks ranged from $69 to $71 per dry ton. On the other hand, delivered cost of agricultural biomass ranged from $77.60 to $102.50 per dry ton. The total production area required for fast growing feedstocks was estimated as between 22,500 to 27,000 ...
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Ecologists have advocated retaining various densities of canopy trees in harvest units in Pacific Northwest forests, In contrast to clear-cutting, this practice may better emulate the patterns of disturbance and structural complexity typical of natural forests in the region. Several ecological attributes, including vertebrate habitat diversity, are thought to be associated with stands of complex structure. The goal of this study was to determine bird abundance in canopy retention sites relative to other common stand types in the Pacific Northwest and to develop habitat functions for extrapolating bird abundance across current and future landscapes. We used data from five previous studies in the west central Cascades of Oregon to compare bird abundance and to develop habitat functions for forest birds across a wide range of natural and managed stand structures and ages. The 67 stands included clearcuts, retention sites, young closed-canopy plantations, mature stands, and old-growth stands. ANOVA revealed that 18 of the 23 species included in the analysis differed significantly in abundance among the stand types, with some species being primarily associated with each of the stand types. The habitat variables used to build habitat functions included tree density by size class, mean tree diameter, and variation in tree diameter. Linear, polynomial, and various nonlinear regression models were evaluated for each bird species. Significant habitat functions were generated for 17 of the 23 bird species. The analyses identified four habitat-use guilds among the 17 bird species: open-canopy; open-canopy with dispersed large trees, structurally complex closed-canopy; and structurally simple closed-canopy guilds. This study is the first in the Pacific Northwest to compare bird abundances across natural stands, traditionally managed plantations, and stands managed under ecological forestry approaches, The results suggested that canopy tree retention benefits many, but not all, of the bird species we studied, Moreover, the nonlinear responses of bird abundance revealed thresholds in tree density at which bird abundance changed dramatically. Knowledge of these thresholds allow managers to design stands for specific biodiversity objectives. The habitat functions presented here can be used to predict bird abundance based on habitat measurements derived from field data, remotely sensed data, or output from computer models of forest dynamics.
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As the use of short-rotation coppice willow crops increases, this vegetation type will comprise a greater extent of the landscape, yet its attendant effects on biodiversity remain poorly understood. In this study we characterized the avian and small mammal communities of willow crops that were established for phytoremediation and biomass production in industrial settling basins and compared these communities to those of surrounding areas of naturally-established perennial herbaceous-woody vegetation. Overall, we observed 33 bird species and five small mammal species in five focal sites (i.e., areas consisting of willow crops and adjacent vegetation) and 20 bird species and four small mammal species in two reference sites (i.e., areas of the settling basins without willow crops). For birds and small mammals, focal sites supported slightly greater average species richness and average abundances of all species combined than reference sites. Within focal sites, willow crops supported fewer species and similar combined abundances compared to adjacent areas. Importantly, community and individual species responses varied with the duration of time since coppicing. More small mammal species and individuals used willow crops in the year following coppicing because of their herbaceous undergrowth, while more birds tended to use older willow crops. Collectively, these results indicate that willow crops located within areas of perennial herbaceous-woody vegetation provide some benefits to bird and small mammal populations and that promoting a herbaceous layer in willow crops and maintaining multiple age classes of willows in the landscape simultaneously are likely to enhance the value of willow crops for biodiversity.
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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 Mm(3) in 2010 to 2,359,000-3,271,000 Mm(3) 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 Mm(3) consumption in 2010 to 21,000-58,400 Mm(3) 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 m(3)GJ(-1) (0.1-0.5 m(3)GJ(-1) consumption), while such policies in the liquid fuel sector would reduce withdrawal/manipulation by 0.4-0.7 m(3)GJ(-1) (0.2-0.3 m(3)GJ(-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 Mm(3) (20,300 Mm(3) 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.
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A growing interest in cellulosic biofuels, coupled with the economic challenges faced by nonindustrial private forestland (NIPF) owners of the Southern United States, presents a unique opportunity to use forest biomass as a feedstock for developing bioenergy markets. This study uses a cost-benefit analysis framework to calculate the profitability for three simulated NIPF slash pine (Pinus elliottii) plantations under multiple feedstock production levels. Also, the unit cost of cellulosic ethanol production considering both the two-stage dilute sulfuric acid (2SDSA) and proposed synthesis gas ethanol catalytic conversion (SGECC) processes is calculated through a discounted cash flow methodology. The results show that the bioenergy market opportunity increases land values by $28.56-37.50/ac. The calculated unit cost of production is found to be $2.39/gallon under the 2SDSA process and $1.16/gallon for the SGECC process. The overall analysis indicates that ethanol production from Southern slash pine plantations offers a promising option for biofuel production, but that further advancements are necessary in the ethanol conversion phase.
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Alternative management regimes of loblolly pine (Pinus taeda) plantations were evaluated and compared for joint production of timber and biomass and exclusively for biomass production in Mississippi. The PTAEDA3.1 computerized yield simulator was used to predict growth effects of various site preparation techniques, initial planting densities, and thinning activities. Evaluation criteria included land expectation values (LEVs) and mean annual increment. Results indicated that sites with a site index of 50-70 (base age 25) yielded average annual stem residues of 0.86-1.20 tons/ac, from which 39.8-47.4 gallons of ethanol could be produced. Inclusion of pulpwood as a feedstock would approximately double biofuel production. Culminating sustainable annual outputs of total stem biomass exclusively for biofuel production using intensive site preparation was unprofitable on all sites because of high site preparation costs and low biomass prices. Sensitivity analyses indicated that LEVs and optimal management strategies were sensitive to changes in price of biomass relative to that of sawtimber. The rise of the relative biomass price would increase woody biomass availability for biofuels. It would also boost intensive management practices, such as intensive site preparation, closer initial tree spacings, earlier thinnings, and shorter rotation ages.
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Indicators of the environmental sustainability of biofuel production, distribution, and use should be selected, measured, and interpreted with respect to the context in which they are used. The context of a sustainability assessment includes the purpose, the particular biofuel production and distribution system, policy conditions, stakeholder values, location, temporal influences, spatial scale, baselines, and reference scenarios. We recommend that biofuel sustainability questions be formulated with respect to the context, that appropriate indicators of environmental sustainability be developed or selected from more generic suites, and that decision makers consider context in ascribing meaning to indicators. In addition, considerations such as technical objectives, varying values and perspectives of stakeholder groups, indicator cost, and availability and reliability of data need to be understood and considered. Sustainability indicators for biofuels are most useful if adequate historical data are available, information can be collected at appropriate spatial and temporal scales, organizations are committed to use indicator information in the decision-making process, and indicators can effectively guide behavior toward more sustainable practices.
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A guide to data collection, modeling and inference strategies for biological survey data using Bayesian and classical statistical methods. This book describes a general and flexible framework for modeling and inference in ecological systems based on hierarchical models, with a strict focus on the use of probability models and parametric inference. Hierarchical models represent a paradigm shift in the application of statistics to ecological inference problems because they combine explicit models of ecological system structure or dynamics with models of how ecological systems are observed. The principles of hierarchical modeling are developed and applied to problems in population, metapopulation, community, and metacommunity systems. The book provides the first synthetic treatment of many recent methodological advances in ecological modeling and unifies disparate methods and procedures. The authors apply principles of hierarchical modeling to ecological problems, including * occurrence or occupancy models for estimating species distribution * abundance models based on many sampling protocols, including distance sampling * capture-recapture models with individual effects * spatial capture-recapture models based on camera trapping and related methods * population and metapopulation dynamic models * models of biodiversity, community structure and dynamics * Wide variety of examples involving many taxa (birds, amphibians, mammals, insects, plants) * Development of classical, likelihood-based procedures for inference, as well as Bayesian methods of analysis * Detailed explanations describing the implementation of hierarchical models using freely available software such as R and WinBUGS * Computing support in technical appendices in an online companion web site.
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Applied Hierarchical Modeling in Ecology: Distribution, Abundance, Species Richness offers a new synthesis of the state-of-the-art of hierarchical models for plant and animal distribution, abundance, and community characteristics such as species richness using data collected in metapopulation designs. These types of data are extremely widespread in ecology and its applications in such areas as biodiversity monitoring and fisheries and wildlife management. This first volume explains static models/procedures in the context of hierarchical models that collectively represent a unified approach to ecological research, taking the reader from design, through data collection, and into analyses using a very powerful class of models. Applied Hierarchical Modeling in Ecology, Volume 1 serves as an indispensable manual for practicing field biologists, and as a graduate-level text for students in ecology, conservation biology, fisheries/wildlife management, and related fields. Provides a synthesis of important classes of models about distribution, abundance, and species richness while accommodating imperfect detection Presents models and methods for identifying unmarked individuals and species Written in a step-by-step approach accessible to non-statisticians and provides fully worked examples that serve as a template for readers' analyses Includes companion website containing data sets, code, solutions to exercises, and further information
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Increased demand and government mandates for bioenergy crops in the United States could require a large allocation of agricultural land to bioenergy feedstock production and substantially alter current landscape patterns. Incorporating bioenergy landscape design into land-use decision making could help maximize benefits and minimize trade-offs among alternative land uses. We developed spatially explicit landscape scenarios of increased bioenergy crop production in an 80-km radius agricultural landscape centered on a potential biomass-processing energy facility and evaluated the consequences of each scenario for bird communities. Our scenarios included conversion of existing annual row crops to perennial bioenergy grasslands and conversion of existing grasslands to annual bioenergy row crops. The scenarios explored combinations of four biomass crop types (three potential grassland crops along a gradient of plant diversity and one annual row crop [corn]), three land conversion percentages to bioenergy crops (10%, 20%, or 30% of row crops or grasslands), and three spatial configurations of biomass crop fields (random, clustered near similar field types, or centered on the processing plant), yielding 36 scenarios. For each scenario, we predicted the impact on four bird community metrics: species richness, total bird density, species of greatest conservation need (SGCN) density, and SGCN hotspots (SGCN birds/ha ≥ 2). Bird community metrics consistently increased with conversion of row crops to bioenergy grasslands and consistently decreased with conversion of grasslands to bioenergy row crops. Spatial arrangement of bioenergy fields had strong effects on the bird community and in some cases was more influential than the amount converted to bioenergy crops. Clustering grasslands had a stronger positive influence on the bird community than locating grasslands near the central plant or at random. Expansion of bioenergy grasslands onto marginal agricultural lands will likely benefit grassland bird populations, and bioenergy landscapes could be designed to maximize biodiversity benefits while meeting targets for biomass production.
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This document is based on previous documentation of the nationally standardized Forest Inventory and Analysis database (Hansen and others 1992; Woudenberg and Farrenkopf 1995; Miles and others 2001). Documentation of the structure of the Forest Inventory and Analysis database (FIADB) for Phase 2 data, as well as codes and definitions, is provided. Examples for producing population level estimates are also presented. This database provides a consistent framework for storing forest inventory data across all ownerships for the entire United States. These data are available to the public.
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We studied abundance and species composition of birds and small mammals on hybrid poplar (Populus sp.) biomass plantations and other nearby land use types in the northcentral United States. There were few differences in mammal abundance or diversity between hybrid poplar plantations and rowcrop or small-grain fields. Avian abundance and species richness were consistently higher on plantations than in rowcrop or small-grain fields. Our findings suggest little negative site-level effect on songbirds or small mammals resulting from replacement of rowcrop or small-grain fields with hybrid poplar; our study did not address fragmentation or other landscape-level issues. Avian and mammalian abundance and diversity generally were considerably lower on plantations than in forests and non-wooded wildlands. Birds appeared to be more strongly attracted to plantations in agricultural regions than in forested landscapes. Limited use of plantations by area-sensitive and long-distance. Neotropical migrant bird species may reflect the relatively young age or small size of the plantations we studied. Mammal abundance and species richness were higher in patches where clones had failed or weed control was ineffective, suggesting that incorporating heterogeneity as a specific design feature may be one approach for managing plantations for biodiversity.
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Intensively managed forests in the southeastern United States are a potential source of cellulosic bioenergy and, as conversion technologies improve and demand increases, a greater land area may be required to produce biofuel feedstocks. However, responses of wildlife to forest-based biofuel production are largely unknown. We examined the 4-year response of rodent populations and assemblages to a range of biofuel production regimes, including harvesting residual woody debris and intercropping switchgrass (Panicum virgatum), in an intensively managed loblolly pine (Pinus taeda) forest in eastern North Carolina, USA. We investigated abundance, demography, and community response of rodents in a randomized and replicated field experiment using mark-recapture techniques during 2009–2012. Whereas removal of downed woody biomass did not affect abundance, diversity, or demography of rodents, we detected species-specific effects of incorporating switchgrass. After switchgrass was well established, invasive house mice (Mus musculus) were most abundant in plots with switchgrass. In contrast, white-footed mice (Peromyscus leucopus) were commonly captured in plots without switchgrass and other rodents were not affected by biofuel treatments. Across the study, natural succession exerted greater effects on rodent species and the rodent community than biofuel production regimes. As remaining logs and stumps decay and become limiting, downed wood may become more important to rodents. Our results indicate that intercropping switchgrass and harvesting residual woody material had limited effects on rodents in the Coastal Plain of North Carolina, USA within 4 years of stand establishment. © 2014 The Wildlife Society.
Article
In the United States, government-mandated growth in the production of crops dedicated to biofuel (agrofuels) is predicted to increase the demands on existing agricultural lands, potentially threatening the persistence of populations of grassland birds they support. We review recently published literature and datasets to (1) examine the ability of alternative agrofuel crops and their management regimes to provide habitat for grassland birds, (2) determine how crop placement in agricultural landscapes and agrofuel-related land-use change will affect grassland birds, and (3) identify critical research and policy-development needs associated with agrofuel production. We find that native perennial plants proposed as feedstock for agrofuel (switchgrass, Panicum virgatum, and mixed grass–forb prairie) have considerable potential to provide new habitat to a wide range of grassland birds, including rare and threatened species. However, industrialization of agrofuel production that maximizes biomass, homogenizes vegetation structure, and results in the cultivation of small fields within largely forested landscapes is likely to reduce species richness and/or abundance of grassland-dependent birds. Realizing the potential benefits of agrofuel production for grassland birds’ conservation will require the development of new policies that encourage agricultural practices specifically targeting the needs of grassland specialists. The broad array of grower-incentive programs in existence may deliver new agrofuel policies effectively but will require coordination at a spatial scale broader than currently practiced, preferably within an adaptive-management framework.
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Native tallgrass prairie and wetland habitat in the Prairie Pothole Region of the United States have declined over the past two centuries. Bird communities using these habitats have also experienced widespread declines that are often attributed to severe habitat loss and fragmentation. We estimated the change, or turnover, in bird populations in the Eagle Lake Wetland Complex, Iowa, with ongoing grassland and wetland restoration by linking geographic information system data and bird surveys in different land cover types (hayland, pasture, restored grassland, restored wetland and rowcrop agriculture) during the 1999-2001 breeding seasons. Habitat restoration efforts primarily converted rowcrop agriculture and pastures into grassland and wetland habitat. Based on land conversion, abundances of most species have likely increased in the area, including many species of management concern. Yet a few species, such as killdeer (Charadrius vociferus), have probably decreased in abundance. This estimation approach and these estimates provided a critical first step for evaluating restoration efforts; however, information on demographic parameters, such as nesting success, in restored areas is needed for understanding how restoration ultimately affects bird populations.
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The economics of producing cellulosic ethanol using loblolly pine, natural mixed hardwood, Eucalyptus, corn stover, and switchgrass as feedstocks was simulated in Aspen Plus using the thermochemical process via indirect gasification and mixed alcohol synthesis developed by NREL. Outputs from the simulation were linked to an economic analysis spreadsheet to estimate NPV, IRR, payback and to run further sensitivity analysis of the different combinations of feedstocks. Results indicate that forest-based feedstocks including loblolly pine, natural hardwood and eucalyptus may present more attractive financial returns when compared to switchgrass and corn stover, mainly due to their composition (%C, %H, %ash) and alcohol yield. Simulated alcohol yields from forest-based feedstock were significantly higher than from switchgrass and corn stover. Models fed with switchgrass and corn stover, also demonstrated greater sensitivity to changes in ethanol price, alcohol yield, capital investment and biomass costs. Furthermore, moisture content of receiving feedstocks greatly affected the economics of the biorefinery. A difference of −10% in the moisture content of the receiving feedstock affected the NPV of the simulated project by +25% (with respect to central NPV of ~$192million).
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Growing demand for alternative energy sources has contributed to increased biofuel production, but the effects on biodiversity of land-use change to biofuel crops remain unclear. Using a meta-analysis for crops being used or considered in the US, we find that vertebrate diversity and abundance are generally lower in biofuel crop habitats relative to the non-crop habitats that these crops may replace. Diversity effects are greater for corn than for pine and poplar, and birds of conservation concern experience greater negative effects from corn than species of less concern. Yet conversion of row-crop fields to grasslands dedicated to biofuels could increase local diversity and abundance of birds. To minimize impacts of biofuel crops on biodiversity, we recommend management practices that reduce chemical inputs, increase heterogeneity within fields, and delay harvests until bird breeding has ceased. We encourage research that will move us toward a sustainable biofuels economy, including the use of native plants, development of robust environmental criteria for evaluating biofuel crops, and integrated cost-benefit analysis of potential land-use change.
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There are times when birds reproduce at higher rates in places where they are less abundant, limiting the generally accepted value of bird counts as environmental indicators. But how often, and under what circumstances, does this happen? In 109 published cases involving 67 species across North America and Europe, higher density sites displayed greater recruitment per capita and per unit of land area in 72% and 85% of cases, respectively. The frequency of negative relationships between abundance and reproductive success did not differ between different kinds of birds or habitats. However, density was negatively related to reproductive success more often in areas of human disturbance than in relatively natural areas. Although further study is needed to confirm the generality of this pattern, especially in areas such as the tropics, results suggest that birds can fail to recognize ecological traps or opportunities in landscapes that differ from those in which they evolved.
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In the near future, wood from the 130 000 km2 of pine plantations in the southern United States could provide much of the feedstock for emerging bioenergy industries. Research and operational experience show that total plantation biomass productivity exceeding 22.4 Mg ha−1 y−1 green weight basis with rotations less than 25 years are biologically possible, financially attractive, and environmentally sustainable. These gains become possible when intensively managed forest plantations are treated as agro-ecosystems where both the crop trees and the soil are managed to optimize productivity and value. Intensive management of southern US pine plantations could significantly increase the amount of biomass available to supply bioenergy firms. Results from growth and yield simulations using models and a financial analysis suggest that if the 130 000 km2 of cutover pine plantations and an additional 20 000 km2 of planted idle farmland are intensively managed in the most profitable regimes, up to 77.5 Tg green weight basis of woody biomass could be produced annually. However, questions exist about the extent to which intensive management for biomass production can improve financial returns to owners and whether they would adopt these systems. The financial analysis suggests providing biomass for energy from pine plantations on cutover sites is most profitable when intensive management is used to produce a mixture of traditional forest products and biomass for energy. Returns from dedicated biomass plantations on cutover sites and idle farmland will be lower than integrated product plantations unless prices for biomass increase or subsidies are available.
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We compared the abundance and nesting success of avian species in Conservation Reserve Program (CRP) fields during the summer with that in rowcrop fields over 5 years (1991-1995) for 6 midwestern states (Ind., la., Kans., Mich., Mo., and Nebr.). Field techniques were standardized in all states. CRP fields consisted of either perennial introduced grasses and legumes (CP1) or perennial native grasses (CP2), and the plant species seeded in CRP fields differed within and among the states. Disturbances to CRP fields included mowing (partial or complete), application of herbicides, and burning. The height, vertical density, and canopy coverage of vegetation in CRP fields were measured in each state; values for these measurements were particularly low in Kansas. Mean annual total bird abundance in CRP fields ranged from 4.9 to 29.3 birds/km of transect. The most abundant species on CRP fields differed among states but included red-winged blackbirds (Agelaius phoeniceus), grasshopper sparrows (Ammodramus savannarum), and dickcissels (Spiza americana). Although the total number of bird species was similar in CRP and rowcrop fields across the region, bird abundance was 1.4-10.5 times greater in the former. Nests of 33 bird species were found in CRP fields compared with only 10 species in rowcrop fields, and the number of nests found was 13.5 times greater in CRP fields. Nest success in CRP fields was 40% overall; predation was the greatest cause of nest failure. Long-term farm set-aside programs that establish perennial grass cover, such as the CRP, seem to provide many benefits for grassland birds, including several species for which conservation is a great concern.
Article
The Energy Independence and Security Act (P.L. 110-140, H.R. 6) is an omnibus energy policy law that consists mainly of provisions designed to increase energy efficiency and the availability of renewable energy. This report describes the key provisions of the enacted law, summarizes the legislative action on H.R. 6, and provides a summary of the provisions under each of the titles in the law. Many analysts in the CRS Resources, Science, and Industry Division contributed to this report; their names and contact information are located on the back of the summary page.
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Land area occupied by tallgrass prairie has declined throughout the midcontinental United States during the past 2 centuries, and migratory birds breeding in these habitats have also experienced precipitous population declines. State and federal agencies have responded by restoring and reconstructing grassland habitats. To understand consequences of restoration for grassland bird populations, we combined demographic data collected over 4 breeding seasons (1999–2002) in northern Iowa, USA, with population projection models to estimate population growth rates of 2 declining migratory songbirds, dickcissels (Spiza americana) and bobolinks (Dolichonyx oryzivorus). To determine what parameters were critical for conservation of these species, we estimated relative contributions of nest predation, brood parasitism by brown-headed cowbirds (Molothrus ater), annual survival, and renesting to population growth using elasticity analysis. Based on model simulations, the population growth rate for dickcissels was not high enough to be stable without immigration into the area (λ < 1). For bobolinks, populations could only be stable (λ = 1) if annual survival was relatively high (adult survival >0.7, with juvenile survival between 0.2 and 0.5). Population growth rates were most sensitive to adult survival across a wide range of parameter estimates, whereas sensitivity to brood parasitism and renesting were consistently low. Elasticities associated with nest predation were highly variable and dependent on survival estimates. In the absence of changes in other demographic parameters, eliminating brood parasitism would not be enough to ensure stable populations of either species. Only management focused on increasing adult survival or decreasing nest predation could produce stable populations. Our results underscore the need for reliable adult survival estimates and conservation strategies focused throughout all phases of the annual cycle. In addition, our modeling approach provides an effective framework for investigating the importance of demographic parameters to population growth rates of birds that are influenced by nest predation, brood parasitism, and renesting. Although habitat restoration is one of the few alternatives for conserving communities in threatened landscapes, restoration strategies also need to have positive effects on population dynamics for species of concern, which has not been demonstrated in this grassland system.
Article
Short-rotation woody cropping (SRWC) refers to silvicultural systems designed to produce woody biomass using short harvest cycles (1–15 years), intensive silvicultural techniques, high-yielding varieties, and often coppice regeneration. Recent emphasis on alternatives to fossil fuels has spurred interest in producing SRWC on privately owned and intensively managed forests of North America. We examined potential bird and small mammal response at the stand level to conversion of existing, intensively managed forests to SRWCs using meta-analysis of existing studies. We found 257 effect sizes for birds (243 effect sizes) and mammals (14 effect sizes) from 8 studies involving Populus spp. plantations. Diversity and abundance of bird guilds were lower on short-rotation plantations compared with reference woodlands, while abundance of individual bird species was more variable and not consistently higher or lower on SRWC plantations. Shrub-associated birds were more abundant on SRWC plantations, but forest-associated and cavity-nesting birds were less abundant. Effects on birds appeared to decrease with age of the SRWC plantation, but plantation age was also confounded with variation in the type of reference forest used for comparison. Both guilds and species of mammals were less abundant on SRWC plantations. These conclusions are tentative because none of these studies directly compared SRWC plantations to intensively managed forests. Plantations of SRWCs could contribute to overall landscape diversity in forest-dominated landscapes by providing shrubby habitat structure for nonforest species. However, extensive conversion of mature or intensively managed forests to SRWC would likely decrease overall diversity, especially if they replace habitat types of high conservation value.
Article
Bioenergy from crops is expected to make a considerable contribution to climate change mitigation. However, bioenergy is not necessarily carbon neutral because emissions of CO2, N2O and CH4 during crop production may reduce or completely counterbalance CO2 savings of the substituted fossil fuels. These greenhouse gases (GHGs) need to be included into the carbon footprint calculation of different bioenergy crops under a range of soil conditions and management practices. This review compiles existing knowledge on agronomic and environmental constraints and GHG balances of the major European bioenergy crops, although it focuses on dedicated perennial crops such as Miscanthus and short rotation coppice species. Such second-generation crops account for only 3% of the current European bioenergy production, but field data suggest they emit 40% to >99% less N2O than conventional annual crops. This is a result of lower fertilizer requirements as well as a higher N-use efficiency, due to effective N-recycling. Perennial energy crops have the potential to sequester additional carbon in soil biomass if established on former cropland (0.44 Mg soil C ha−1 yr−1 for poplar and willow and 0.66 Mg soil C ha−1 yr−1 for Miscanthus). However, there was no positive or even negative effects on the C balance if energy crops are established on former grassland. Increased bioenergy production may also result in direct and indirect land-use changes with potential high C losses when native vegetation is converted to annual crops. Although dedicated perennial energy crops have a high potential to improve the GHG balance of bioenergy production, several agronomic and economic constraints still have to be overcome.
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Summary • Territory quality may affect individual fitness and contribute to density-dependent reproduction, with repercussions on population regulation. We investigated the probable causes and population consequences of spatio-temporal variations in territory quality, measured by occupancy, in eight black kite Milvus migrans Boddaert populations, one of them studied for 10 years (Lake Lugano) and the rest for 4–5 years. • Over a period of years, the occupation rate of territories varied from a random pattern. Some territories were preferred while others were avoided. On return from migration, males and females settled earlier on high-occupancy territories. • The positive association between territory occupancy and breeding performance held in all years of study at Lake Lugano, and in six of seven tested populations. As a result, high-occupancy territories contributed most of the young produced by each population. • The occupation rate of the overall 225 territories was related positively to food availability and negatively to mortality risk, measured as proximity to the nearest eagle owl Bubo bubo Linnaeus nest. • At the population level, spatial variation in mean occupancy was positively correlated with spatial variation in mean productivity, suggesting that mean occupancy could be used as a measure of overall habitat quality and population performance. • In the Lake Lugano area, a higher proportion of low quality territories was occupied in years of higher density and annual productivity was related negatively to its coefficient of variation. However, annual productivity was not related significantly to the proportion of low quality territories occupied, so support for the theory of site-dependent population regulation was only partial. • In a review of 22 studies of territory occupancy in 17 species, occupancy always deviated from a random pattern in species in which it was tested and was always correlated with productivity and/or with some other measure of territory quality. Our results confirm the importance of prioritizing conservation of high quality territories. Occupancy may be a reliable method of quality assessment, especially for populations in which not all territories are always occupied, or for species in which checking occupancy is easier than finding nests.
Article
The 2007 Energy Independence and Security Act mandates a five-fold increase in US biofuel production by 2022. Given this ambitious policy target, there is a need for spatially explicit estimates of landscape suitability for growing biofuel feedstocks. We developed a suitability modeling approach for two major US biofuel crops, corn (Zea mays) and switchgrass (Panicum virgatum), based upon the use of two presence-only species distribution models (SDMs): maximum entropy (Maxent) and support vector machines (SVM). SDMs are commonly used for modeling animal and plant distributions in natural environments, but have rarely been used to develop landscape models for cultivated crops. AUC, Kappa, and correlation measures derived from test data indicate that SVM slightly outperformed Maxent in modeling US corn production, although both models produced significantly accurate results. When compared with results from a mechanistic switchgrass model recently developed by Oak Ridge National Laboratory (ORNL), SVM results showed higher correlation than Maxent results with models fit using county-scale point inputs of switchgrass production derived from expert opinion estimates. However, Maxent results for an alternative switchgrass model developed with point inputs from research trial sites showed higher correlation to the ORNL model than the corresponding results obtained from SVM. Further analysis indicates that both modeling approaches were effective in predicting county-scale increases in corn production from 2006 to 2007, a time period in which US corn production increased by 24%. We conclude that presence-only methods are a powerful first-cut tool for estimating relative land suitability across geographic regions in which candidate biofuel feedstocks can be grown, and may also provide important insight into potential land-use change patterns likely to be associated with increased biofuel demand.
Article
The dawn chorus is a widely observed phenomenon. One of the common, but inadequately studied, explanations for the occurrence of the dawn chorus is based on the rationale that atmospheric turbulence, which impairs acoustic communication, is least at dawn, and thus singing at dawn in some way maximizes signal performance. To investigate what possible acoustic benefit is gained through singing at dawn, we transmitted Swamp Sparrow Melospiza georgiana and White-throated Sparrow Zonotrichia albicollis song through open grassland and closed forest both at dawn and at midday. The transmitted songs were re-recorded at four distances from 25 to 100 m. Our results show that the mean overall absolute transmission quality of the signals was not significantly better at dawn than at midday. However, the signal transmission quality was significantly more consistent at dawn than at midday. Also, in general, signal transmission quality decreased with increasing distance. Variability in the transmission quality increased with distance for the White-throated Sparrow song, but not for the Swamp Sparrow song. Consistency in signal transmission quality is a factor that, arguably, is crucial for the identity function of song. This study strongly supports the acoustic transmission hypothesis as an explanation for the existence of the dawn chorus while the demonstration of variability as a key factor in singing at dawn is novel.
Article
Federal mandates to increase biofuel production in North America will require large new tracts of land with potential to negatively impact biodiversity, yet empirical information to guide implementation is limited. Because the temperate grassland biome will be a production hotspot for many candidate feedstocks, production is likely to impact grassland birds, a group of major conservation concern. We employed a multiscaled approach to investigate the relative importance of arthropod food availability, microhabitat structure, patch size and landscape-scale habitat structure and composition as factors shaping avian richness and abundance in fields of one contemporary (corn) and two candidate cellulosic biomass feedstocks (switchgrass and mixed-grass prairie) not currently managed as crops. Bird species richness and species density increased with patch size in prairie and switchgrass, but not in corn, and was lower in landscapes with higher forest cover. Perennial plantings supported greater diversity and biomass of arthropods, an important food for land birds, but neither metric was important in explaining variation in the avian community. Avian richness was higher in perennial plantings with greater forb content and a more diverse vegetation structure. Maximum bird species richness was commonly found in fields of intermediate vegetation density and grassland specialists were more likely to occur in prairies. Our results suggest that, in contrast to corn, perennial biomass feedstocks have potential to provide benefits to grassland bird populations if they are cultivated in large patches within relatively unforested landscapes. Ultimately, genetic improvement of feedstock genets and crop management techniques that attempt to maximize biomass production and simplify crop vegetation structure will be likely to reduce the value of perennial biomass plantings to grassland bird populations.