Homogeneous Landscape Research Articles

Long‐Term Shifts in U.S. Nitrogen Sources and Sinks Revealed by the New TREND‐Nitrogen Data Set (1930–2017)

AbstractReactive nitrogen (N) fluxes have increased tenfold over the last century, driven by increases in population, shifting diets, and increased use of commercial N fertilizers. Runoff of excess N from intensively managed landscapes threatens drinking water quality and disrupts aquatic ecosystems. Excess N is also a major source of greenhouse gas emissions from agricultural soils. While N emissions from agricultural landscapes are known to originate from not only current‐year N input but also legacy N accumulation in soils and groundwater, there has been limited access to fine‐scale, long‐term data regarding N inputs and outputs over decades of intensive agricultural land use. In the present work, we synthesize population, agricultural, and atmospheric deposition data to develop a comprehensive, 88‐year (1930–2017) data set of county‐scale components of the N mass balance across the contiguous United States (Trajectories Nutrient Dataset for nitrogen [TREND‐nitrogen]). Using a machine‐learning algorithm, we also develop spatially explicit typologies for components of the N mass balance. Our results indicate a large range of N trajectory behaviors across the United States due to differences in land use and management and particularly due to the very different drivers of N dynamics in densely populated urban areas compared with intensively managed agricultural zones. Our analysis of N trajectories also demonstrates a widespread functional homogenization of agricultural landscapes. This newly developed typology of N trajectories improves our understanding of long‐term N dynamics, and the underlying data set provides a powerful tool for modeling the impacts of legacy N on past, present, and future water quality.

Does the use of biological traits predict a smooth landscape of ecosystem functioning?

The biodiversity crisis has increased interest in understanding the role of biodiversity for ecosystem functioning. Functional traits are often used to infer ecosystem functions to increase our understanding of these relationships over larger spatial scales. The links between specific traits and ecosystem functioning are, however, not always well established. We investigated how the choice of analyzing either individual species, selected modalities, or trait combinations affected the spatial patterns observed on a sandflat and how this was related to the natural variability in ecosystem functioning. A large dataset of 400 benthic macrofauna samples was used to explore distribution patterns. We hypothesized that (1) if multiple species (redundancy) represent a trait combination or a modality their spatial patterns would be smoothed out, and (2) the lost spatial variability within a trait combination or modality, due to the smoothing effect, would potentially affect their utility for predicting ecosystem functioning (tested on a dataset of 24 samples). We predicted that species would show heterogeneous small spatial patterns, while modalities and trait combinations would show larger and more homogeneous patterns because they would represent a collection of many distributions. If modalities and trait combinations are better predictors of ecosystem functioning than species, then the smoother spatial patterns of modalities and trait combinations would result in a more homogeneous landscape of ecosystem function and the number of species exhibiting specific traits would provide functional redundancy. Our results showed some smoothing of spatial patterns progressing from species through modalities to trait combinations, but generally spatial patterns reflected a few dominant key species. Moreover, some individual modalities and species explained more or equal proportions of the variance in the ecosystem functioning than the combined traits. The findings thus suggest that only some spatial variability is lost when species are combined into modalities and trait combinations and that a homogeneous landscape of ecosystem function is not likely.

Crop diversity benefits carabid and pollinator communities in landscapes with semi‐natural habitats

Abstract In agricultural landscapes, arthropods provide essential ecosystem services such as biological pest control and pollination. Intensified crop management practices and homogenization of landscapes have led to declines among such organisms. Semi‐natural habitats, associated with high numbers of these organisms, are increasingly lost from agricultural landscapes but diversification by increasing crop diversity has been proposed as a way to reverse observed arthropod declines and thus restore ecosystem services. However, whether or not an increase in the diversity of crop types within a landscape promotes diversity and abundances of pollinating and predaceous arthropods, and how semi‐natural habitats might modify this relationship, are not well understood. To test how crop diversity and the proportion of semi‐natural habitats within a landscape are related to the diversity and abundance of beneficial arthropod communities, we collected primary data from seven studies focusing on natural enemies (carabids and spiders) and pollinators (bees and hoverflies) from 154 crop fields in Southern Sweden between 2007 and 2017. Crop diversity within a 1‐km radius around each field was positively related to the Shannon diversity index of carabid and pollinator communities in landscapes rich in semi‐natural habitats. Abundances were mainly affected by the proportion of semi‐natural habitats in the landscape, with decreasing carabid and increasing pollinator numbers as the proportion of this habitat type increased. Spiders showed no response to either crop diversity or the proportion of semi‐natural habitats. Synthesis and applications. We show that the joint effort of preserving semi‐natural habitats and promoting crop diversity in agricultural landscapes is necessary to enhance communities of natural enemies and pollinators. Our results suggest that increasing the diversity of crop types can contribute to the conservation of service‐providing arthropod communities, particularly if the diversification of crops targets complex landscapes with a high proportion of semi‐natural habitats.

The role of the social network structure on the spread of intensive agriculture: an example from Navarre, Spain

Social networks influence decision-making in agricultural landscapes by affecting how farmers access knowledge and resources. However, researchers ignore the disparate structures built to access different kinds of knowledge and resources and the social mechanisms that take place on such farmers’ advice networks. We explored the role of social networks in decision-making among farmers in Navarre (Spain) to understand how and why some practices spread among farming communities. Social network analysis allows us to understand how farmers in this region share both knowledge and resources, and the potential implications of this sharing for the landscape. We find that large-scale farmers undertaking intensive land management are at the core of the network in this region, controlling the flow of knowledge and resources related to farm management, policy, technology, and finance. The central position of these farmers in the social network, and their reputation, is key to the spread of intensive farming practices in the region, which ultimately may lead to homogenization of local agricultural landscapes. Understanding farmer network structures in a context of agricultural intensification can help tease out the social mechanisms, such as farmers joining each other in cooperatives, behind the spread of agricultural practices.

The edge of the Empire: diet characterization of medieval Rome through stable isotope analysis

This paper aims to define the dietary profile of the population of early medieval Rome (fifth–eleventh centuries CE) by carbon and nitrogen stable isotope analysis. This period was characterized by deep changes in the city’s economic, demographic, and social patterns, probably affecting its inhabitants’ nutritional habits. Carbon and nitrogen stable isotope analysis of bone collagen was used to detect the nutritional profile of 110 humans from six communities inhabiting the city center of Rome and one from the ancient city of Gabii. Thirteen faunal remains were also analyzed to define the ecological baseline of the medieval communities. The isotopic results are consistent with a diet mainly based on the exploitation of C3 plant resources and terrestrial fauna, while the consumption of aquatic resources was detected only among the San Pancrazio population. Animal protein intake proved to be similar both among and within the communities, supporting a qualitatively homogenous dietary landscape in medieval Rome. The comparison with isotopic data from the Imperial Age allowed us to detect a diachronic nutritional transition in ancient Rome, in which the collapse of the Empire, and in particular the crisis of economic power and the trade system, represented a tipping point for its population’s nutritional habits.

Landscape dynamics on insular environments of South-east mediterranean Europe

Mediterranean islands are characterized by high biodiversity and cultural value. As the human demand for natural resources increases, the need for assessing the future landscape is prerequisite. This study aimed to simulate the future landscape composition and structure of the Ionian Islands (Western Greece). To do so, we integrated the Future Land Use Model and Markov Chain analysis, taking into consideration fifteen socio-environmental predictors. The results showed that the landscape of the Ionian Islands is expected to develop into two major patterns. The first pattern refers to the expected increase of forests and scrublands, shaping a homogenous landscape. Whereas, the second pattern reveals an expected degradation of natural vegetation, shaping a highly fragmented landscape. In all circumstances, the built-up areas are anticipated to extend, mainly near to touristic hot-spots. This study demonstrated that contemporary spatial simulation approaches, along with various socio-environmental factors offer an important tool for effective landscape management.

Heterogeneous landscapes of urban greenways in Shenzhen: Traffic impact, corridor width and land use

Greenways are linear green spaces that are widely incorporated as policy instruments to address various urban issues. Heterogeneity is observed among the forms, functions, and activities of greenways. However, a number of studies have viewed urban greenways as homogeneous landscape features despite the increasing heterogeneity of urban greenways caused by transportation development. Taking the “three-legged stool” concept as a theoretical starting point, this article develops a conceptual framework for understanding the heterogeneous landscapes of urban greenways. The framework is then applied to empirical work in Shenzhen. This study shows that traffic impact, corridor width and land use are crucial factors in determining the heterogeneity of urban greenways and resolving the conflicts that result from the overemphasis on the transportation function of greenways. These factors also determine the primary benefits of greenways and differentiate various types of greenways. Based on field observations and empirical data, we identify four types of greenways in Shenzhen: transport greenways, forest greenways, park greenways and rural greenways. Greenways in Shenzhen have apparent heterogeneity in recreational attractiveness due to the surrounding landscape and external interference. Furthermore, the majority of Shenzhen greenways are nonmotorized transportation infrastructure with narrow corridors of street greenery. The composition and heterogeneity of greenways in Shenzhen are the result of the “one-size-fits-all” approach to greenway typologies and planning activities, which has become a challenge for multipurpose greenway planning in urban environments. Future efforts should place more emphasis on the heterogeneous landscapes of urban greenways in order to develop improvement strategies associated with specific policy goals.

Does the simplification of activity systems produce landscape homogenization?

Activity systems determine the land-use strategies that ultimately shape landscapes. Identifying the reasoning behind the decision making on land use strategies can help to understand how humans contribute to shaping landscapes and to design appropriate land management plans. We studied changes in land-use strategies employed by rural communities, as well as their impact on the landscape in Atzalan, Mexico. For this, we conducted interviews in households distributed throughout the municipality, documenting their activities, resources, and motivations related to land use. We also compared local perceptions of landscape change with that detected by remote sensing analysis. Our results indicate that the activity system in Atzalan features a multiplicity of economic strategies with traditional activities at their core, as well as other more intensified systems such as monocultures and pastures. However, traditional activities are largely giving way to intensified land uses, leading to landscape homogenization. The spatial and temporal distribution of the dominant land covers throughout the municipality reflects a dependency on the environmental context, social structure and land accessibility. People are aware of changes in the landscape and recognize their role in these transformations, mostly due to impacts on the forest and crop cover. Simplification of the activity system has been reflected in the homogenization of the landscape and could prevent households from maintaining diversified strategies of multiple uses of resources.

Ecological Specialization and Rarity of Arable Weeds: Insights from a Comprehensive Survey in France.

The definition of “arable weeds” remains contentious. Although much attention has been devoted to specialized, segetal weeds, many taxa found in arable fields also commonly occur in other habitats. The extent to which adjacent habitats are favorable to the weed flora and act as potential sources of colonizers in arable fields remains unclear. In addition, weeds form assemblages with large spatiotemporal variability, so that many taxa in weed flora are rarely observed in plot-based surveys. We thus addressed the following questions: How often do weeds occur in other habitats than arable fields? How does including field edges extend the taxonomic and ecological diversity of weeds? How does the weed flora vary across surveys at different spatial and temporal scales? We built a comprehensive dataset of weed taxa in France by compiling weed flora, lists of specialized segetal weeds, and plot-based surveys in agricultural fields, with different spatial and temporal coverages. We informed life forms, biogeographical origins and conservation status of these weeds. We also defined a broader dataset of plants occupying open habitats in France and assessed habitat specialization of weeds and of other plant species absent from arable fields. Our results show that many arable weeds are frequently recorded in both arable fields and non-cultivated open habitats and are, on average, more generalist than species absent from arable fields. Surveys encompassing field edges included species also occurring in mesic grasslands and nitrophilous fringes, suggesting spill-over from surrounding habitats. A total of 71.5% of the French weed flora was not captured in plot-based surveys at regional and national scales, and many rare and declining taxa were of Mediterranean origin. This result underlines the importance of implementing conservation measures for specialist plant species that are particularly reliant on arable fields as a habitat, while also pointing out biotic homogenization of agricultural landscapes as a factor in the declining plant diversity of farmed landscapes. Our dataset provides a reference species pool for France, with associated ecological and biogeographical information.

Fundamental intra-specific differences in plant–water relations in a widespread desert shrub (Artemisia tridentata)

Big sagebrush (Artemisia tridentata) is a widespread and locally dominant shrub that is a key driver of water fluxes and storage in western North America. There are several recognized subspecies of big sagebrush that occupy different microsites across the landscape according to moisture availability, yet little is known about how these subspecies vary in drought tolerance or water management strategies. We measured diurnal and seasonal (i.e., early-, mid-, and late summer) variation in water status and transport efficiency, transpiration, and stomatal regulations in two subspecies of big sagebrush (A.t. wyomingensis and A.t. vaseyana) at the Reynolds Creek Critical Zone Observatory in southwestern Idaho. We hypothesized that water status, transport efficiency, and stomatal regulations would be greater in A.t. vaseyana compared to A.t. wyomingensis, because the first subspecies occupies wetter microsites. Predawn and midday water potentials were up to 2× more negative in A.t. wyomingensis compared to A.t. vaseyana, and transpiration was up to ~ 4× greater in A.t. vaseyana compared to A.t. wyomingensis. A.t. vaseyana was more isohydric with ~ 1.5× greater stomatal sensitivity to atmospheric vapor pressure deficit and a smaller hydroscape, compared to A.t. wyomingensis. Our data demonstrate that there are fundamental differences in plant–water relations among these subspecies that constitute the vast, but not homogeneous sagebrush landscapes. These important differences can have implications for modeling water fluxes in big sagebrush-dominated communities at shrub to ecosystem scales.

Rewilding and restoring cultural landscapes in Mediterranean mountains: Opportunities and challenges

Farmland abandonment and the decline of livestock activity in the Mediterranean mountains have resulted in dramatic landscape changes, including the generalized expansion of shrublands and forests, and the homogenization of the old cultural landscapes. This process has a variety of consequences from ecological, geomorphological and hydrological points of view, as well as from the perspectives of land management and public awareness. An intense debate currently surrounds the discussion and evaluation of rewilding (the process of passively allowing woody encroachment, as well as the reintroduction of large mammals) as an opportunity for enhancing biodiversity and restoring original landscapes after centuries of human activity versus ecological restoration (activities leading to the recovery of degraded ecosystems, including clearing and light human activity). There is no clear consensus regarding the best way to improve the ecological relationships and functioning within an ecosystem. Biodiversity and sustainability can be seen under different levels of human pressure and landscape transformation; total farmland abandonment is not always the best alternative, particularly when local inhabitants aim to sustain themselves using local resources. Many geographers and ecologists consider that extensive stockbreeding in a partially open landscape is a rational way to (i) improve landscape organization, (ii) increase flows and turnover within the ecosystems, (iii) increase the diversity of plants and animals that benefit from a relatively light human presence, and (iv) reduce wildfire risk. However, it has proven challenging for land managers and stockbreeders to clear the best old abandoned fields and “construct” a sustainable, balanced landscape that combines forests, shrublands and open lands. Private landowner involvement and support from the general public is crucial for both funding and the long-term maintenance of benefits. The best old fields should be cleared in the context of high-resolution knowledge of the topography, grassland characteristics, grassland cycles and livestock management. Such efforts are likely to be an excellent opportunity to introduce compatibility between light human activity and increases in biodiversity and sustainability for many marginal mountains, where land abandonment and general forest/shrub recovery are the inevitable tendencies. This paper examines some of the contrasting positions of the scientific community regarding the rewilding or ecological restoration of mountain landscapes, and briefly highlights some experiences in which intentional clearing of old abandoned fields has benefited stockbreeding, biodiversity, runoff generation and wildfire risks. Notably, we describe a sub-Mediterranean valley of the Iberian Range, Northern Spain, as an example. In the long term, we find that the intentional clearing of the best old fields allows the slow organization of a final landscape that will be more useful for local inhabitants, thereby helping to reverse human depopulation in these regions.

Spread externalities and the implications of heterogeneous ecological capacity constraints

We develop a spatial-dynamic model of resource management in the presence of externalities, such as the spread of harmful invasive species, and show that ecological capacity constraints influence optimal management strategies across space. We use integer-programming methods to solve for optimal control strategies in both homogeneous and heterogeneous landscapes. Using the spread of gypsy moths as an application, our results show that optimal levels of control vary over space in landscapes with heterogeneous capacity constraints. Optimal outcomes depend on the marginal costs and damages associated with the externality and the emergence of spread externalities from relative differences in population levels between adjacent patches. In models with high degrees of heterogeneity, we show that a naïve policy assuming homogeneous carrying capacity results in a significantly higher welfare losses from the externality.

Spatial distribution of urban greenspace in response to urban development from a multi-scale perspective

Urban expansion and renewal are one of the major drivers affecting urban landscapes worldwide. Considerable research has been conducted to understand how urban greenspace (UG) changes in response to urbanization at various scales from individual patches to landscapes. However, most of these studies have been conducted at a single scale, and little is known from a multiple scale perspective. Here, we present a multi-scale analytical framework to quantify the spatial pattern of greenspace and its change by integrating rank-size distribution, urban–rural gradient analysis and hotspots analysis. We applied this framework to nine major Chinese cities using 2.5 m resolution Advanced Land Observation Satellite and Systeme Probatoire d’Observation de la Terre imagery captured in 2005 and 2010. We found the multi-scale assessment provides integrated and synthesized information about the dynamics of UG that would otherwise be missed. First, the hotspots analysis revealed dramatic change in UG for all the nine cities, and such change tended to be spatially clustered. Second, the spatial heterogeneity of UG decreased from 2005 to 2010 for all the cities as a result of the increase of UG in urban core areas and loss of UG in the urban periphery, resulting in landscape homogenization along the urban–rural gradient. Third, substantial loss of UG co-occurred with densification of urban land development, indicating potential adverse impacts of compact city on urban greenery. Infill development became dominant, with percentage ranging from 52.7% in Shanghai to 90.6% in Nanjing, resulting in more compact urban form. This study underscores the importance of a multi-scale perspective on understanding the spatial distribution of UG and its change, and its response to urban development.

Present Status of Musculoskeletal Radiology in Europe: International Survey by the European Society of Musculoskeletal Radiology.

No official data exist on the status of musculoskeletal (MSK) radiology in Europe. The Committee for National Societies conducted an international survey to understand the status of training, subspecialization, and local practice among the European Society of Musculoskeletal Radiology (ESSR) partner societies. This article reports the results of that survey. An online questionnaire was distributed to all 26 European national associations that act as official partner societies of the ESSR. The 24 questions were subdivided into six sections: society structure, relationship with the national radiological society, subspecialization, present radiology practice, MSK interventional procedures, and MSK ultrasound. The findings of our study show a lack of standardized training and/or accreditation methods in the field of MSK radiology at a national level. The European diploma in musculoskeletal radiology is directed to partly overcome this problem; however, this certification is still underrecognized. Using certification methods, a more homogeneous European landscape could be created in the future with a view to subspecialist training. MSK ultrasound and MSK interventional procedures should be performed by a health professional with a solid knowledge of the relevant imaging modalities and sufficient training in MSK radiology. Recognition of MSK radiology as an official subspecialty would make the field more attractive for younger colleagues as well as attracting the brightest and best, an important key to further development of both clinical and academic radiology. KEY POINTS: · Standardized training and/or accreditation methods in the field of MSK radiology is lacking at a national level.. · With certification methods, such as the European diploma in musculoskeletal radiology, a more homogeneous European landscape could be created in the future with a view to subspecialist training.. · Recognition of MSK radiology as an official subspecialty would make the field more attractive for younger colleagues as well as attracting the brightest and best, an important key to further development of both clinical and academic radiology..

Recent introgression between Taiga Bean Goose and Tundra Bean Goose results in a largely homogeneous landscape of genetic differentiation

Several studies have uncovered a highly heterogeneous landscape of genetic differentiation across the genomes of closely related species. Specifically, genetic differentiation is often concentrated in particular genomic regions (“islands of differentiation”) that might contain barrier loci contributing to reproductive isolation, whereas the rest of the genome is homogenized by introgression. Alternatively, linked selection can produce differentiation islands in allopatry without introgression. We explored the influence of introgression on the landscape of genetic differentiation in two hybridizing goose taxa: the Taiga Bean Goose (Anser fabalis) and the Tundra Bean Goose (A. serrirostris). We re-sequenced the whole genomes of 18 individuals (9 of each taxon) and, using a combination of population genomic summary statistics and demographic modeling, we reconstructed the evolutionary history of these birds. Next, we quantified the impact of introgression on the build-up and maintenance of genetic differentiation. We found evidence for a scenario of allopatric divergence (about 2.5 million years ago) followed by recent secondary contact (about 60,000 years ago). Subsequent introgression events led to high levels of gene flow, mainly from the Tundra Bean Goose into the Taiga Bean Goose. This scenario resulted in a largely undifferentiated genomic landscape (genome-wide FST = 0.033) with a few notable differentiation peaks that were scattered across chromosomes. The summary statistics indicated that some peaks might contain barrier loci while others arose in allopatry through linked selection. Finally, based on the low genetic differentiation, considerable morphological variation and incomplete reproductive isolation, we argue that the Taiga and the Tundra Bean Goose should be treated as subspecies.

Can pedotransfer functions based on environmental variables improve soil total nutrient mapping at a regional scale?

Numerous pedotransfer functions (PTFs) have been developed to predict the soil properties of interest from other soil properties and, less commonly, from environmental variables. However, only a few PTFs have been developed to predict soil nutrients using environmental variables and to extrapolate them to characterize spatial soil variations at a regional scale. In this study, we attempted to develop PTFs for the total nitrogen (TN), total phosphorus (TP) and total potassium (TK) concentrations in three typical pedo-climatic areas of China (Fujian Province, Jiangsu Province and Qilian Mountains) with diverse climate, terrain and soil types. A series of linear PTFs were developed to quantify the effect of terrain and climate on the predictive relations between the soil nutrients and other measured soil properties and environmental variables. In addition, digital soil mapping (DSM) based on the random forest (RF) technique was performed to test the hypothesis that the best-fit PTFs could be extrapolated, based on soil maps and environmental variables, to describe regional soil variations in the soil nutrients. The root mean square errors (RMSEs) of the best-fit PTFs for TN, TP and TK ranged from 0.21 to 0.79 g kg−1, 0.20 to 0.58 g kg−1, and 3.68 to 5.00 g kg−1, respectively. Different RMSEs were produced by DSM, namely 0.37-1.89 g kg−1, 0.19−0.56 g kg−1 and 3.79-4.83 g kg−1 for TN, TP and TK, respectively. PTFs provided a sound basis for database compilation if the soil properties were highly correlated. However, the extrapolation of best-fit PTFs to regional scales yielded greater errors than those produced by DSM. The comparison results reveal the limitations of PTFs and suggest that their performance could be improved by using environmental covariates or by fitting data in areas with relatively homogeneous soil landscapes. The DSM techniques may provide satisfactory alternatives to predict soil data at both regional and plot scales.

Coexistence of Sympatric Carnivores in a Relatively Homogenous Landscape and the Effects of Environmental Factors on Site Occupation

We used a total of 589 independent photos of three species — the leopard cat (Prionailurus bengalensis), red fox (Vulpes vulpes) and North China leopard (Panthera pardus japonensis) — from 81 camera traps to study coexistence of those sympatric carnivores. We computed an occupancy model and ran single-season and two-species models to examine patterns in occupancy, detection and coexistence. Our study revealed simultaneous presence of red foxes and leopards both in space and in time. Leopard cats and leopards avoided each other, and red foxes and leopard cats coexisted particularly at night. Vegetation cover was found to be the most important factor in candidate models for site occupation.

Agricultural Landscape Composition Linked with Acoustic Measures of Avian Diversity

Measuring, monitoring, and managing biodiversity across agricultural regions depends on methods that can combine high-resolution mapping of landscape patterns with local biodiversity observations. This study explores the potential to monitor biodiversity in agricultural landscapes by linking high-resolution remote sensing with passive acoustic monitoring. Land cover maps produced using a small unmanned aerial system (UAS) and PlanetScope (PS) satellite imagery were used to investigate relationships between landscape patterns and an acoustically derived biodiversity index (vocalizing bird species richness) across 12 agricultural sample locations equipped with acoustic recorders in Iowa, USA during the 2018 growing season. Statistical assessment revealed a significant direct association between vocalizing bird richness and percent noncrop vegetation cover. High spatial resolution (1 m) UAS mapping produced stronger statistical associations than PS-based maps (3 m) for landscape composition metrics. Landscape configuration metrics (Shannon’s diversity index, contagion, perimeter-area-ratio, and circumscribing circle index) were either cross-correlated with composition metrics or unusable owing to complete landscape homogeneity in some agricultural landscape samples. This study shows that high resolution mapping of noncrop vegetation cover can be linked with acoustic monitoring of unique bird vocalizations to provide a useful indicator of biodiversity in agricultural landscapes.

Exploring adoption price effects on life cycle inventory results

The environmental impact of a product may change according to who adopts it, where it is adopted, and how it is used. Market forces are an inherent part of consequential LCA and the practice of coupling economic models with life cycle inventory data has increased in popularity. Nevertheless, the actual relationship between the price of a commodity and potential changes to its life cycle inventory has rarely been discussed explicitly. The adoption price effect refers to a change in a product’s environmental impact associated with a change in price, calculated on a functional unit basis. The price of a product influences the type and quantity of incumbent product(s) it displaces. This study provides insights on when the adoption price of a product is likely to influence its life cycle inventory and also identifies conditions where adoption price is expected to have negligible effects on inventory results. A switchgrass bioenergy case is used to demonstrate the adoption price effect on life cycle inventory results when introducing a new product (i.e., switchgrass) into a system with multiple incumbents (i.e., crops, hay, pasture). This study estimates the adoption price effect on nutrient emissions by coupling biogeochemical models with a simplified economic breakeven model that estimates potential switchgrass adoption. In this case study, high switchgrass prices correspond to nitrate emission reductions that are three times greater than low switchgrass prices (0.67 kg N reduced/Mg switchgrass vs 0.21 kg N reduced/Mg switchgrass). The large adoption price effect found within the Southeastern USA is due to the highly heterogeneous landscape in the region. There is no single dominant land use, each incumbent product has a different environmental baseline, and each is displaced at a different switchgrass price range. Meanwhile, the adoption price effect is expected to be negligible in mostly homogenous landscapes, such as the more commonly studied Corn Belt, which has a single dominant incumbent in the form of corn-soy production. In addition to the specific case study, this analysis discusses general adoption conditions likely to lead to adoption price effects when conducting consequential LCA.

Assessment of spatial genetic structure to identify populations at risk for infection of an emerging epizootic disease.

Understanding the geographic extent and connectivity of wildlife populations can provide important insights into the management of disease outbreaks but defining patterns of population structure is difficult for widely distributed species. Landscape genetic analyses are powerful methods for identifying cryptic structure and movement patterns that may be associated with spatial epizootic patterns in such cases.We characterized patterns of population substructure and connectivity using microsatellite genotypes from 2,222 white‐tailed deer (Odocoileus virginianus) in the Mid‐Atlantic region of the United States, a region where chronic wasting disease was first detected in 2009. The goal of this study was to evaluate the juxtaposition between population structure, landscape features that influence gene flow, and current disease management units.Clustering analyses identified four to five subpopulations in this region, the edges of which corresponded to ecophysiographic provinces. Subpopulations were further partitioned into 11 clusters with subtle (F ST ≤ 0.041), but significant genetic differentiation. Genetic differentiation was lower and migration rates were higher among neighboring genetic clusters, indicating an underlying genetic cline. Genetic discontinuities were associated with topographic barriers, however.Resistance surface modeling indicated that gene flow was diffuse in homogenous landscapes, but the direction and extent of gene flow were influenced by forest cover, traffic volume, and elevational relief in subregions heterogeneous for these landscape features. Chronic wasting disease primarily occurred among genetic clusters within a single subpopulation and along corridors of high landscape connectivity.These results may suggest a possible correlation between population substructure, landscape connectivity, and the occurrence of diseases for widespread species. Considering these factors may be useful in delineating effective management units, although only the largest features produced appreciable differences in subpopulation structure. Disease mitigation strategies implemented at the scale of ecophysiographic provinces are likely to be more effective than those implemented at finer scales.