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Shifting work zones from daytime to nighttime is a potential solution to air quality issues on roadway with high traffic volume and where it is undesirable to close lanes during peak hours. The expected benefit of such shifting is to reduce total fuel consumption and on-road vehicle emissions. However, the magnitude of emission reductions and air quality impacts has not been examined comprehensively at work zones. The study presented in this paper investigated the traffic-related emission impacts of work zones using an urban freeway case study. A VISSIM test bed combined with the Environmental Protection Agency’s MOVES emission model was used to estimate total emissions assuming daytime and nighttime lane-closure scenarios. Vehicle emissions were estimated using a link-based method and operating mode-based method. The results from both methods demonstrated that nighttime construction has a significant impact on both traffic speeds and vehicle emissions, primarily as a result of reductions in vehicle miles traveled. In addition, a horizontal comparison between the results from the two methods was made to assess the impact of different emission estimation approaches. The outcomes from the comparison highlight the potential importance of the operating mode-based approach for accurately estimate total traffic emission quantities when data or simulations are available.

Grasslands and open savannas are transitioning to shrub-dominated or tree-dominated landscapes. This phenomenon, often referred to as woody plant encroachment, is occurring globally. The outcomes of interactions among the various drivers of this change differ biogeographically; in semi-arid and subhumid regions they are often related to grazing-induced changes in fire regimes. Two important theoretical and conceptual frameworks are emerging that help us understand the underlying mechanisms of these transformations and inform approaches for maintaining and restoring grasslands and open savannas: alternative stable state theory (ASST) and pyric herbivory. Alternative stable state theory is a way of explaining, understanding, and predicting ecosystem state transitions in dual-life-form systems, and pyric herbivory is built on the notion that reciprocal, spatially distributed interactions between grazing and fire are a key to maintaining grassland and open savanna landscapes. Considered in tandem, ASST provides insights into rates and dynamics of grass–woody vegetation transitions, with pyric herbivory providing a conceptual basis for designing sustainable, site-specific management strategies. Future progress will hinge on experimental evaluations of these linked frameworks and their subsequent refinement over longer time frames in an adaptive management context.

Urban landscapes provide habitat for many species, including domesticated and feral honey bees, Apis mellifera L. (Hymenoptera: Apidae). With recent losses of managed honey bee colonies, there is increasing interest in feral honey bee colonies and their potential contribution to pollination services in agricultural, natural, and urban settings. However, in some regions the feral honey bee population consists primarily of Africanized honey bees. Africanized honey bees (AHB) are hybrids between European honey bees and the African honey bee, Apis mellifera scutellataLepeletier, and have generated economic, ecological, and human health concerns because of their aggressive behavior. In this study, we used two long-term datasets (7–10 years) detailing the spatial and temporal distribution of AHB colonies in Tucson, AZ, USA, where feral colonies occupy a variety of cavities including water meter boxes. A stage-structured matrix model was used to elucidate the implications of nest site selection and the effects of colony terminations on the structure and dynamics of the AHB population. Our results suggest that Tucson's AHB population is driven by a relatively small number of ‘source’ colonies that escape termination (ca. 0.165 colonies per km2 or 125 colonies in total), although immigrating swarms and absconding colonies from the surrounding area may have also contributed to the stability of the Tucson AHB population. Furthermore, the structure of the population has likely been impacted by the number and spatial distribution of water meter boxes across the city. The study provides an example of how urban wildlife populations are driven by interactions among landscape structure, human management, and behavioral traits conferred by an invasive genotype.

Transparent methods of estimating CO2 emissions from transportation sources are necessary to evaluate mitigation strategies. This study proposes a framework to assess the regional impact of roadway designs on CO2 emissions. First, three roadway infrastructure configurations were designed to improve the traffic flow at intersections and interchanges. Second, the economical and environmental life-cycle cost assessments of constructing and maintaining new infrastructures were developed. Then, the effects of infrastructure on regional vehicle CO2 emissions were modeled using a simulation-based dynamic traffic assignment model coupled with the U.S. Environmental Protection Agency's MOtor Vehicle Emission Simulator (MOVES) model. The case study estimated that converting 72 stop signs to roundabouts within El Paso, TX, reduced daily vehicular CO2 emissions by more than 50 tonnes, paying back the CO2 from construction and maintenance within 2.5 to 2.9 years. The roundabout modifications' cost-effectiveness ranged from $30 to $130 per tonne of CO2 over a 30-year assessment.

Recent studies suggest that the transportation sector is a major contributor to fine particulate matter (PM2.5) in urban areas. A growing body of literature indicates PM2.5 exposure can lead to adverse health effects, and that PM2.5 concentrations are often elevated close to roadways. The transportation sector produces PM2.5 emissions from combustion, brake wear, tire wear, and resuspended dust. Traffic-related resuspended dust is particulate matter, previously deposited on the surface of roadways that becomes resuspended into the air by the movement of traffic. The objective of this study was to use regulatory guidelines to model the contribution of resuspended dust to near-road traffic-related PM2.5 concentrations. The U.S. Environmental Protection Agency (EPA) guidelines for quantitative hotspot analysis were used to predict traffic-related PM2.5 concentrations for a small network in Dallas, Texas. Results show that the inclusion of resuspended dust in the emission and dispersion modeling chain increases prediction of near-road PM2.5 concentrations by up to 74%. The results also suggest elevated PM2.5 concentrations near arterial roads. Our results are discussed in the context of human exposure to traffic-related air pollution.

Eastern hemlock (Tsuga canadensis Carriere) and the Carolina hemlock (Tsuga caroliniana Engelmann) are ecologically important tree species in eastern North America forests that are currently threatened by the hemlock woolly adelgid (HWA, Adelges tsugae Annand, Hemiptera: Adelgidae). HWA has spread rapidly from its original introduction site into new areas. Once present, HWA kills its hosts over a period of 4 to 10 years leading to a phenomenon that is known scientifically and colloquially as hemlock decline. To date, quarantine, chemical management, and biocontrol efforts have failed to curb the spread of the HWA. As such, forest management efforts are now being redirected towards developing an understanding of the effects of hemlock removal on vegetation dynamics, changes in forest composition, and changes in ecosystem function. In this study, we parameterize a spatially explicit landscape simulation model LANDIS II for a specific forested region of the southern Appalachians. Parameterization involves defining the life-history attributes of 37 tree species occupying 11 ecological zones and is based on knowledge of: current vegetation composition data, recent historic management and fire regimes, and life-history traits of each species. The parameterized model is used to explore a simple scenario of catastrophic hemlock mortality likely to occur as a result of HWA herbivory. Our results emphasize that hemlock is an important foundation species. When hemlock is removed from the system, forest composition changes considerably with a greater presence of shade intolerant pine and oak species. Additionally, hemlock removal leads to a period of transient, relatively unstable vegetation dynamics as the forest communities restructure.

A geographic information system (GIS) application was developed containing 18 layers of spatially explicit environmental data relevant to characterization of the eight officially recognized American Viticultural Areas (AVAs) for wine grape (Vitis vinifera) production in Texas. GIS climate variables included daily minimum temperature, daily maximum temperature, daily average temperature (TAVG), growing degree days (GDD), ripening period mean temperature (RPMT), annual precipitation, solar radiation, vapor pressure, and number of frost days. Soil attributes were texture, depth, available water capacity, pH, permeability, and bulk density. These data were used to develop interpretative descriptions of Texas AVAs published on the Winegrowing Regions of Texas web site, which also serves as the public portal to the interactive GIS (AVATXIS). Individuals can use AVATXIS to access data and visualize spatial variability on maps to characterize Texas AVAs for any or all of the environmental factors and to examine spatial relationships among factors.

The Pecan ipmPIPE Program has been operational throughout the Pecan Belt for four growing seasons. During this period, new interactive deliverables including near real time, locally relevant risk assessment tools for major pests, educational materials useful in conducting best management practices, a pecan library, pesticide search engines, and an interactive database have been developed and made available to the public using the Internet. Using metrics from several sources shows that ∼50% of Texas pecan producers have readily adopted this new technology; producers from other states are shown to behave similarly, albeit fewer metrics were available for comparison. The annual economic impact in Texas is estimated to be $1 million, which is expected to increase 2–3 fold if similar metrics were available to assess this belt-wide. The program is expected to increase in value to stakeholders as more producer adoption occurs and as Internet tools become increasingly sophisticated. The need for profess...

Internet based, Information Technology (IT) offers opportunities to agricultural scientists to share information important to production agriculture. We offer an objective view for how IT can be used to manipulate data, information, and knowledge. The application of these technologies in other domains serves as a lesson to how they might be used to benefit production agriculture. We discuss three related technologies that have the potential to improve information flow among agricultural stakeholders and identify a number of trends (increased robustness, standardization of data formats, and reduced cost of implementation) that make them impor- tant tools for production agriculture.

Small Footprint LiDAR (Light Detection And Ranging) has been proposed as an effective tool for measuring detailed biophysical characteristics of forests over broad spatial scales. However, by itself LiDAR yields only a sample of the true 3D structure of a forest. In order to extract useful forestry relevant information, this data must be interpreted using mathematical models and computer algorithms that infer or estimate specific forest metrics. For these outputs to be useful, algorithms must be validated and/or calibrated using a sub-sample of `known' metrics measured using more detailed, reliable methods such as field sampling. In this paper we describe a novel method for delineating and deriving metrics of individual trees from LiDAR data based on watershed segmentation. Because of the costs involved with collecting both LiDAR data and field samples for validation, we use synthetic LiDAR data to validate and assess the accuracy of our algorithm. This synthetic LiDAR data is generated using a simple geometric model of Loblolly pine (Pinus taeda) trees and a simulation of LiDAR sampling. Our results suggest that point densities greater than 2 and preferably greater than 4 points per m2 are necessary to obtain accurate forest inventory data from Loblolly pine stands. However the results also demonstrate that the detection errors (i.e. the accuracy and biases of the algorithm) are intrinsically related to the structural characteristics of the forest being measured. We argue that experiments with synthetic data are directly useful to forest managers to guide the design of operational forest inventory studies. In addition, we argue that the development of LiDAR simulation models and experiments with the data they generate represents a fundamental and useful approach to designing, improving and exploring the accuracy and efficiency of LiDAR algorithms.

The Pecan ipm PIPE program provides a new informatics resource that targets ≈5,000 pecan stakeholders located primarily in the southern tier of the United States. Pecan scientists and producers working with information technology experts have developed and delivered this program via the Internet since 2009. Stakeholder participation in and adoption of this resource has grown since inception and is expected to continue as new upgrades are made. More than 41,000 visits have been recorded annually, page loads have increased by 312%, unique visitors have increased by 205%, and return visitors have increased by 32%. Major program features are the interdisciplinary organization of information relevant to conducting pecan integrated pest management aided by search engines that provide real time access to information for the status of the Pecan Nut Casebearer tailored to any location across the pecan belt, and the interactive involvement of scientists and producers in real time that is enabled by informatics.

Africanized honey bees overlap in resource use with humans in urban environments, creating concerns over public health and safety. We obtained data on Africanized honey bee colony removals from water meter boxes in the greater Tucson metropolitan area from 1996 to 2008 to identify characteristics associated with the spatial distribution of Africanized honey bees across the city. Two generalized linear models were constructed to predict the occupation of water meter boxes based on land use, lot/structure characteristics, and the presence of colonies in neighboring water meter boxes. More than 8000 colonies were removed from water meter boxes during the 12-year study period. Colonies were more likely to occupy water meter boxes associated with residential (versus commercial) locations, smaller lots, older structures, closer distances to vacant land, and higher percentages of neighboring water meter boxes with colonies. Occupied water meter boxes and boxes with multiple occupancies were concentrated in South Central Tucson, suggesting this area provides abundant resources for honey bees and that well established, source colonies exist in this area. Locating and removing these source colonies may be the best approach for controlling the Africanized honey bee population in the greater Tucson metropolitan area and similar settings. Also, the regular removal of colonies from water meter boxes is important for the control of Africanized honey bees in the greater Tucson metropolitan area.

Stochastic weather generators are useful tools for exploring the relationship between organisms and their environment. This paper describes a simple weather generator that can be used in ecological modeling projects. We provide a detailed description of methodology, and links to full C++ source code (http://weathergen.sourceforge.net) required to implement or modify the generator. We argue that understanding the principles of weather generation will allow ecologists to tailor a solution for their own requirements. The detailed, repeatable methodology we present demonstrates that weather generation is relatively straightforward for ecologists to implement and modify.

Forest landscape models simulate forest change through time using spatially referenced data across a broad spatial scale (i.e. landscape scale) generally larger than a single forest stand. Spatial interactions between forest stands are a key component of such models. These models can incorporate other spatio-temporal processes such as natural disturbances (e.g. wildfires, hurricanes, outbreaks of native and exotic invasive pests and diseases) and human influences (e.g. harvesting and commercial thinning, planting, fire suppression). The models are increasingly used as tools for studying forest management, ecological assessment, restoration planning, and climate change. In this paper, we define forest landscape models and discuss development, components, and types of the models. We also review commonly used methods and approaches of modeling forest landscapes, their application, and their strengths and weaknesses. New developments in computer sciences, geographic information systems (GIS), remote sensing technologies, decision-support systems, and geo-spatial statistics have provided opportunities for developing a new generation of forest landscape models that are increasingly valuable for ecological research, restoration planning and resource management.

Matrix models have been used to model population growth of organisms for many decades. They are popular because of both their conceptual simplicity and their computational efficiency. For some types of organisms they are relatively accurate in predicting population growth; however, for others the matrix approach does not adequately model growth rate. One of the reasons for the lack of accuracy is that most matrix-based models implicitly assume a specific degree of variability in development times for the organism. Because the variability is implicit, the implied variances are often not verified with experimental data. In this paper, we shall present extensions to the stage-classified matrix models so that organisms with arbitrary means and standard deviations of development times can be modeled.

The forests of southeastern North America are influenced by a variety of disturbances including fire and insect outbreaks. In this paper, we discuss the role of disturbances in structuring forest landscapes with particular emphasis placed on the reciprocal interaction between forest structure and outbreaks of the southern pine beetle (Dendroctonus frontalis Zimmermann). We highlight work in which we are currently involved to illustrate the importance and utility of using spatially explicit forest modeling as a tool for understanding forest–insect interactions and its potential role in determining management strategies.

The reciprocal interaction of landscape structure and ecological processes is a cornerstone of modern landscape ecology. We use a simulation model to show how landscape structure and herbivory interact to influence outbreaks of southern pine beetle (Dendroctonus frontalis Zimmermann) in a landscape representative of the southern Appalachian Mountains, USA. We use LANDIS and its biological disturbance agent module to simulate the effects of landscape composition (proportion of landscape in host area) and host aggregation on the size and severity of insect outbreaks and the persistence of the host species, Table Mountain Pine (Pinus pungens Lamb.). We find that landscape composition is less important in the modeled landscapes than host aggregation in structuring the severity of insect outbreaks. Also, simulated southern pine beetle outbreaks over time tend to decrease the aggregation of host species on the landscape by fragmenting large patches into smaller ones, thereby reducing the severity of future outbreaks. Persistence of Table Mountain pine decreases throughout all simulations regardless of landscape structure. The results of this study indicate that when considering alternative restoration strategies for insect-affected landscapes, it is necessary to consider the patterns of hosts on the landscape as well as the landscape composition.

Question: Can fire be used to maintain Yellow pine (Pinus subgenus Diploxylon) stands disturbed by periodic outbreaks of southern pine beetle? Location: Southern Appalachian Mountains, USA. Methods: We used LANDIS to model vegetation disturbance and succession on four grids representative of xeric landscapes in the southern Appalachians. Forest dynamics of each landscape were simulated under three disturbance scenarios: southern pine beetle, fire, and southern pine beetle and fire, as well as a no disturbance scenario. We compared trends in the abundance of pine and hardwood functional types as well as individual species. Results: Yellow pine abundance and open woodland conditions were best maintained by a combination of fire and southern pine beetle disturbance on both low elevation sites as well as mid-elevation ridges & peaks. On mid-elevation SE-W facing slopes, pine woodlands were best maintained by fire alone. Conclusions: Our simulations suggest that fire can help maintain open pine woodlands in stands affected by southern pine beetle outbreaks.

The southern pine beetle (SPB) (Dendroctonus frontalis) is an important pest of southern U.S. pine forests. During most years, SPB populations occur at low densities and cause little or no damage. However, unpredictable regional outbreaks occur during which tree mortality is extensive and unevenly distributed across a forest landscape. Because the southern forest is a managed, productive ecosystem, SPB outbreaks can have a large impact on forest stakeholders. Although SPB pestilence has led to considerable research, the ecological processes that drive its population dynamics remain uncertain. In this chapter, we discuss how the related concepts of ecological disturbance and systems modeling could be used to address the SPB problem. We describe the importance, scale, and complexity of the system; define our concept of ecological disturbance; and discuss model types that could be applied to the SPB problem. We suggest that characteristics of the system may naturally influence and sometimes impede effective SPB modeling. Specifically, we argue that: (1) instead of conceptualizing SPB damage as an external disturbance, models should be developed that represent SPB as an endogenous property of the system; (2) because the structure and composition of forests are largely driven by human management, it may be useful to model SPB as a coupled social–ecological system; and (3) although the economic importance of SPB naturally drives the need for models that can be used as management and decision support tools, its complex ecology suggests that a broader range of model types is useful to organize, integrate, and communicate data and ideas among researchers.

In this chapter, we examined forest landscape management from a pragmatic (practical as opposed to idealistic) perspective. The discussion was framed in the context of the landscape: a spatially explicit geographic area consisting of recognizable and characteristic component ecosystems. This perspective provided two opportunities for management: the individual component ecosystems and the mosaic of ecosystems that form the landscape per se. A point of emphasis was that forest management is not a generic concept and requires specification of the purpose of management, the spatial unit(s) being managed, the type of forest being managed, and the projected desired outcome of management. Given these constraints, we considered how the principal drivers of landscape change (disturbances, climate, and domestication) influence forest management practices. We concluded with an examination of the concept of designed forest landscapes to provide human-valued goods and services and identified constraints to achieving this end.

The southern pine beetle (Dendroctonus frontalis Zimmermann) is the most destructive insect pest of pine (Pinus spp.) forests in the southern United States. Restoring and managing pine stands infested by southern pine beetle are critically important for forest health and sustainability in the region. The successful restoration of damaged pine forests requires the integration of information of beetle biology and behavior, pine ecology, and landscape restoration. Certain social, economic, and political issues also need to be considered concomitantly. The knowledge for effective restoration and management of southern pine forests has increased greatly in the past decade. In this chapter, we provide a synthesis of new and existing knowledge to address the goals, framework, implementation, social and political impacts on the restoration of the southern pine forests in the context of southern pine beetle. We also provide information on common restoration methods and cost estimates. More effective use and further development of such knowledge could substantially reduce the economic, ecological, and social impact of southern pine beetle within the southern United States and adjacent areas.

A field-scale study of the spatially explicit interaction between the carabidPoecilus cupreusLinnaeus, and two common aphid species (Sitobion avenae(Fabricius) andMetopolophium dirhodum(Walker)) in winter wheat was conducted. All three species showed considerable spatial pattern at the field scale. Activity-density ofP. cupreuswas an order of magnitude higher in the central part of the field compared to its periphery. WhereP. cupreusactivity-density was highest,S. avenaeandM. dirhodumpopulation peaks were delayed. Additionally, in the case ofM. dirhodum, lower maximum counts were evident whereP. cupreusactivity-density was highest. An analysis of the movement of individualP. cupreususing release–recapture indicated that those beetles within the centre of the field exhibited reduced displacement, which may have caused the generation or maintenance of spatial pattern. Crop density was also measured throughout the field. Although crop density had no large-scale spatial pattern, its variability at the small-scale was consistent with an influence on aphid population dynamics. This study demonstrates empirically that both large-scale spatially explicit and small-scale localized processes influenced aphid population dynamics simultaneously.

1. A laser-marking technique is described that may be used to rapidly mass-mark and individually code insects in the field. In this study, ground beetles were marked but the method is applicable to a wide range of organisms with a hard exoskeleton or shell. 2. In a field-scale capture–recapture study conducted in winter wheat, 8266 beetles were coded. Individuals marked in the first week of the trial and recaptured 2 months later retained their codes, which were therefore considered permanent. 3. Assemblages were dominated numerically by Pterostichus cupreus, which formed more than 98% of the total captures. Of the 8046 released P. cupreus, 2269 were recaptured. As an illustration of the use of these data, the POPAN parameterisation of the Jolly–Seber model was used to estimate a whole-field population of 17 237 individuals, equating to a density of 0.46 beetles m−2.