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Exploring social and institutional variation across oak wilt risk management programs in Minnesota, USA
Abstract
The Minnesota Department of Natural Resources, in cooperation with United States Forest Service, has implemented a risk management program to fund local government action aimed at containing the exotic invasive oak tree pathogen, Ceratocystis fagacearum – the causal agent of oak wilt. In administering the oak wilt ReLeaf program, the Minnesota Department of Natural Resources and United States Forest Service sought to facilitate efficient and effective management through enabling and mobilizing local land managers. Because the program is decentralized and because cities and counties are heterogeneous, local land managers take advantage of the program in different ways. Our goal in this study was to document the social and institutional variation in oak wilt management programs at the local (city and county) level, and provide preliminary insights into the causes of the variation. Specifically we asked: what factors constrain and facilitate oak wilt management at the local level; and how do ReLeaf program funds influence local management? To address these questions, we completed 12 in-depth qualitative interviews with foresters and private contractors, yielding information on 16 oak wilt management programs in the Minneapolis/St. Paul metropolitan area, Minnesota, USA. Through our analysis we identified five emergent themes that produce and reflect the overall variation in oak wilt management programs: (1) existence and enforcement of Potential Spore Producing Tree removal ordinances; (2) amount of local resources and potential effect of decrease in state funding; (3) differences across urban and rural areas; (4) differences in program goals and landowner cost sharing structures; and (5) ability to attain the Minnesota Department of Natural Resources’ suppression goal. These findings describe factors contributing to variation across oak wilt management programs, illustrate challenges facing local invasive species management efforts, and provide insights for designing improved invasive species management programs at the federal, state and local level.
... Lack of coordination between stakeholders 3,5,10,13,14,15,16,18,19,28,30,32,34,40,41,48,49,53,54,55,57 Lack of coordination between municipal units 1,3,9,14,15,22,29,34,40,41,43,44,45,49,50,51,53,54,57,58,59 Lack of education of the community 5,7,10,11,13,14,15,17,18,19,21,25,31,32,33,42,49,50,52,57,60 Lack of political support 3,7,10,12,19,21,22,37,50,54,55,59 Lack of public participation in management 10,11,13,16,30,32,33,51,54 Lack of volunteer or community planting 4,13,19,32,33 Resources Lack of budget 4,10,11,14,15,17,18,19,20,21,27,31,36,37,40,41,43,46,49,50,52,53,55,58,59,60 Lack of management plan/policy/strategy 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of knowledge of technical aspects of tree selection (e.g., site condition) 1,5,6,7,25,26,29,34,35,36,38,46,47,52 Lack of knowledge of ecological aspects of tree selection (e.g., native trees, climate change) 1,3,5,12,25,34,46,47,54,56,57,58,59 Lack of personnel 4,26,40,43,44,50,52,55,58,60 Rules of the game Lack of a pro-active management culture 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of coordination of policy at different levels of government 3,19,21,22,24,31,34,37,45,46,49,53,54,58,59,60 Lack of coordination of land management regimes 3,10,17,22,24,25,28,33,46,48 Lack of monitoring of trees 12,26,33,34,35,36,38,45 Discourses Framing of urban forestry as an ecosystem services delivery mechanism 7,8,16,23,39,47,56,57 Planting trees only for aesthetic or environmental benefits 1,7,8,43,46,47,55,58 Social vs. biophysical measures of urban forest program success 3,33,44,45 Lack of voice of arborists or urban foresters in management decisions 2, 5 ...
... Lack of coordination between stakeholders 3,5,10,13,14,15,16,18,19,28,30,32,34,40,41,48,49,53,54,55,57 Lack of coordination between municipal units 1,3,9,14,15,22,29,34,40,41,43,44,45,49,50,51,53,54,57,58,59 Lack of education of the community 5,7,10,11,13,14,15,17,18,19,21,25,31,32,33,42,49,50,52,57,60 Lack of political support 3,7,10,12,19,21,22,37,50,54,55,59 Lack of public participation in management 10,11,13,16,30,32,33,51,54 Lack of volunteer or community planting 4,13,19,32,33 Resources Lack of budget 4,10,11,14,15,17,18,19,20,21,27,31,36,37,40,41,43,46,49,50,52,53,55,58,59,60 Lack of management plan/policy/strategy 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of knowledge of technical aspects of tree selection (e.g., site condition) 1,5,6,7,25,26,29,34,35,36,38,46,47,52 Lack of knowledge of ecological aspects of tree selection (e.g., native trees, climate change) 1,3,5,12,25,34,46,47,54,56,57,58,59 Lack of personnel 4,26,40,43,44,50,52,55,58,60 Rules of the game Lack of a pro-active management culture 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of coordination of policy at different levels of government 3,19,21,22,24,31,34,37,45,46,49,53,54,58,59,60 Lack of coordination of land management regimes 3,10,17,22,24,25,28,33,46,48 Lack of monitoring of trees 12,26,33,34,35,36,38,45 Discourses Framing of urban forestry as an ecosystem services delivery mechanism 7,8,16,23,39,47,56,57 Planting trees only for aesthetic or environmental benefits 1,7,8,43,46,47,55,58 Social vs. biophysical measures of urban forest program success 3,33,44,45 Lack of voice of arborists or urban foresters in management decisions 2, 5 ...
... Lack of coordination between stakeholders 3,5,10,13,14,15,16,18,19,28,30,32,34,40,41,48,49,53,54,55,57 Lack of coordination between municipal units 1,3,9,14,15,22,29,34,40,41,43,44,45,49,50,51,53,54,57,58,59 Lack of education of the community 5,7,10,11,13,14,15,17,18,19,21,25,31,32,33,42,49,50,52,57,60 Lack of political support 3,7,10,12,19,21,22,37,50,54,55,59 Lack of public participation in management 10,11,13,16,30,32,33,51,54 Lack of volunteer or community planting 4,13,19,32,33 Resources Lack of budget 4,10,11,14,15,17,18,19,20,21,27,31,36,37,40,41,43,46,49,50,52,53,55,58,59,60 Lack of management plan/policy/strategy 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of knowledge of technical aspects of tree selection (e.g., site condition) 1,5,6,7,25,26,29,34,35,36,38,46,47,52 Lack of knowledge of ecological aspects of tree selection (e.g., native trees, climate change) 1,3,5,12,25,34,46,47,54,56,57,58,59 Lack of personnel 4,26,40,43,44,50,52,55,58,60 Rules of the game Lack of a pro-active management culture 1,4,7,9,11,17,19,24,26,27,31,34,39,40,41,45,46,47,49,50,52,58,59,60 Lack of coordination of policy at different levels of government 3,19,21,22,24,31,34,37,45,46,49,53,54,58,59,60 Lack of coordination of land management regimes 3,10,17,22,24,25,28,33,46,48 Lack of monitoring of trees 12,26,33,34,35,36,38,45 Discourses Framing of urban forestry as an ecosystem services delivery mechanism 7,8,16,23,39,47,56,57 Planting trees only for aesthetic or environmental benefits 1,7,8,43,46,47,55,58 Social vs. biophysical measures of urban forest program success 3,33,44,45 Lack of voice of arborists or urban foresters in management decisions 2, 5 ...
... Related studies on tree-wind interactions have been carried out in many places over the world, such as Asia (Hong Kong [13], Macau [14], and Mainland China [15]), the United States [16][17][18], Canada [19][20][21], the United Kingdom [22,23], Europe (Portugal [24], Czech Republic [25], and Germany [26]), and Australia [27]. Meanwhile, the field measurements were conducted on many tree species, and the sample tree species can be categorized into deciduous broadleaf trees (Lime trees (Tilia × europaea) [28], Oak trees (Quercus) [16,25,29,30], Maple trees (Acer spp.) [26], Hickory trees (Carya spp.) [31] and Pear trees (Pyrus spp.) [32]) and conifers trees (Pine (Pinus spp.) [18,30,33], Spruce (Picea spp.) [20,34,35], Douglas fir (Pseudotsuga menziesii) [36] and Ironwood (Casuarina equisetifolia) [37]). ...
... Related studies on tree-wind interactions have been carried out in many places over the world, such as Asia (Hong Kong [13], Macau [14], and Mainland China [15]), the United States [16][17][18], Canada [19][20][21], the United Kingdom [22,23], Europe (Portugal [24], Czech Republic [25], and Germany [26]), and Australia [27]. Meanwhile, the field measurements were conducted on many tree species, and the sample tree species can be categorized into deciduous broadleaf trees (Lime trees (Tilia × europaea) [28], Oak trees (Quercus) [16,25,29,30], Maple trees (Acer spp.) [26], Hickory trees (Carya spp.) [31] and Pear trees (Pyrus spp.) [32]) and conifers trees (Pine (Pinus spp.) [18,30,33], Spruce (Picea spp.) [20,34,35], Douglas fir (Pseudotsuga menziesii) [36] and Ironwood (Casuarina equisetifolia) [37]). The measurement approaches of tree displacement of these two botanical categories are different from the others. ...
Urban forest ecosystems are being developed to provide various environmental services (e.g., the preservation of urban trees) to urban inhabitants. However, some trees are deteriorated asymptomatically without exhibiting an early sign of tree displacement, which results in a higher vulnerability under dynamic wind loads, especially during typhoon seasons, in the subtropical and tropical regions. As such, it is important to understand the tilt and sway behaviors of trees to cope up with the probability of tree failure and to improve the efficacy of tree management. Tree behaviors under wind loads have been broadly reviewed in the past literature, yet thorough discussions on the measurement methods for tree displacement and its analysis of broadleaf specimens are lacking. To understand the behavioral pattern of both broadleaf and conifer species, this paper presents a detailed review of sway behavior analysis from the perspectives of the aerial parts of the individual tree, including tree stem, canopy, and trunk, alongside a highlighted focus on the root–plate movement amid the soil-root system. The analytical approaches associated with the time-space domain and the time-frequency domain are being introduced. In addition to the review of dynamic tree behaviors, an integrated tree monitoring framework based on geographic information systems (GIS) to detect and visualize the extent of tree displacement using smart sensing technology (SST) is introduced. The monitoring system aims to establish an early warning indicator system for monitoring the displacement angles of trees over the territory of Hong Kong’s urban landscape. This pilot study highlights the importance of the monitoring system at an operational scale to be applicable in the urban areas showcasing the practical use of the Internet of Things (IoT) with an in-depth understanding of the wind-load effect toward the urban trees in the tropical and subtropical cities.
... An even more critical constraint in urban areas could be the lack of knowledge about the structure and composition of forests, although the recent increase in urban forestry programs and tools have helped to address this deficiency (Nowak et al., 2008). If analyses in different cities or with different pests provided enough evidence to support cost-share programs (e.g., Kokotovich and Zeilinger, 2011), this could have spill-over benefits by reducing the movement of pests among cities and between cities and recreational areas, thus mitigating an important pathway for the spread of non-native forest pests (Colunga-Garcia et al., 2010;Tobin et al., 2010;Bigsby et al., 2011;Koch et al., 2012). ...
Since its introduction in the 1860s, gypsy moth, Lymantria dispar (L.), has periodically defoliated large swaths of forest in the eastern United States. Prior research has suggested that the greatest costs and losses from these outbreaks accrue in residential areas, but these impacts have not been well quantified. We addressed this lacuna with a case study of Baltimore City. Using two urban tree inventories, we estimated potential costs and losses from a range of gypsy moth outbreak scenarios under different environmental and management conditions. We combined outbreak scenarios with urban forest data to model defoliation and mortality and based the costs and losses on the distribution of tree species in different size classes and land uses throughout Baltimore City. In each outbreak, we estimated the costs of public and private suppression, tree removal and replacement, and human medical treatment, as well as the losses associated with reduced pollution uptake, increased carbon emissions and foregone sequestration. Of the approximately 2.3 M trees in Baltimore City, a majority of the basal area was primary or secondary host for gypsy moth. Under the low outbreak scenario, with federal and state suppression efforts, total costs and losses were $5.540 M, much less than the $63.666 M estimated for the high outbreak scenario, in which the local public and private sectors were responsible for substantially greater tree removal and replacement costs. The framework that we created can be used to estimate the impacts of other non-native pests in urban environments.
In 2013, the U.S. Fish and Wildlife Service (USFWS) Conservation Objectives Team (COT) identified wildfire and the associated conversion of low‐ to mid‐elevation sagebrush (Artemisia tridentata) habitats to invasive annual grass‐dominated vegetation communities as the two primary threats to the sustainability of Greater sage‐grouse (Centrocercus urophasianus, hereafter GRSG) in the western portion of the species range. To facilitate the examination and evaluation of the role fire and invasive plants play in the conservation of GRSG, the USFWS solicited the assistance of the Western Association of Fish and Wildlife Agencies (WAFWA) to conduct a collaborative assessment of the conservation challenges associated with the fire and invasive threat. The results of this collaborative effort led by WAFWA can be found in a series of publications between 2014 and 2019. With respect to the management of invasive plants within the range of the GRSG, WAFWA assessed conditions and activities within the geographic range of GRSG, including parts of 11 states in the western United States and two Canadian provinces represented by the northwestern Great Plains, Great Basin, Snake River Plain, Colorado Plateau, and Columbia Basin. This chapter highlights the results of the assessment and identifies key challenges associated with invasive plant management across the range of the GSRG.
Cost-effective strategies are needed to find and remove diseased trees in forests damaged by pathogens. We develop a model of cost-minimizing surveillance and control of forest pathogens across multiple sites where there is uncertainty about the extent of the infestation in each site and when the goal is to minimize the expected number of new infections. We allow for a heterogeneous landscape, where grid cells may be differentiated by the number of trees, the expected number of infected trees, rates of infection growth, and costs of surveillance and control. In our application to oak wilt in Anoka County, Minnesota, USA, we develop a cost curve associated with saving healthy trees from infection. Assuming an annual infection growth rate of 8%, a $1 million budget would save an expected 185 trees from infection for an average of $5400 per tree.We investigate how more precise prior estimates of disease and reduced detection sensitivity affect model performance. We evaluate rules of thumb, finding that prioritizing sites with high proportions of infected trees is best. Our model provides practical guidance about the spatial allocation of surveillance and control resources for well-studied forest pathogens when only modest information about their geographic distribution is available.
Oak wilt is recognized as one of the most destructive diseases to afflict oak species in the United States. The distribution and development of oak wilt in our eastern and midwestern oak forests has been closely linked to changes in forest stand composition, forest management practices, and pathogen dissemination facilitated by human and vector activity. The potential for oak wilt to spread into southern and western states and its possible impacts are discussed. The Texas experience with an oak wilt epidemic provides useful perspectives and suppression alternatives for other states not yet touched by this malady.
The management of invasive non-native species is a frequent cause of conflict in the field of biodiversity conservation because
perceptions of their costs and benefits differ among stakeholder groups. A lack of cohesion between scientific researchers,
the commercial sector and policy makers lies at the root of a widespread failure to develop and implement sustainable management
practices for invasive species. The crisis of this situation is intensified by drivers stemming from international conventions
and directives to address invasive species issues. There are further direct conflicts between legislative instruments promoting
biodiversity conservation on the one hand while liberalizing trade at the national, European and global level on the other.
The island of Ireland provides graphic illustration of the importance of cross-jurisdictional approaches to biological invasions.
Using primarily Irish examples in this review, we emphasize the importance of approaching risk assessment, risk reduction
and control or eradication policies from a cost-efficient, highly flexible perspective, incorporating linkages between environmental,
economic and social objectives. The need for consolidated policies between Northern Ireland and the Republic of Ireland is
particularly acute, though few model cross-border mechanisms for such consolidation are available. The importance of engaging
affected stakeholders through positive interactions is discussed with regard to reducing the currently fragmented nature of
invasive species management between the two jurisdictions.
This site provides a variety of tools and resources for citizens and local governments interested in developing, revising, or evaluating local tree ordinances. Rather than using a "model ordinance" approach, we describe how tree ordinance development can be integrated with an overall community tree management program. The site includes annotated examples of effective tree ordinance provisions used throughout the country. We also provide detailed descriptions of practical methods used to monitor community tree resources, tree management activities, and community attitudes. USDA Forest Service through the National Urban and Community Forestry Advisory Council, the International Society of Arboriculture, and ESRI, Inc.
Ecological disturbances of forests by insects have a complex array of associated human dimensions presenting complications for natural resource decision making and relationships between stakeholders and managers. This article discusses the human context of forest disturbances by insects by reviewing four cases of bark beetle forest disturbance from British Columbia in Canada, Bavarian Forest National Park in Germany, the Kenai Peninsula in Alaska, and the north central region of Colorado. Findings and lessons learned from these studies are outlined along with their implications for managing forest disturbances by insects in general. Conclusions focus on the need to assess the broad array of impacts and risks perceived by local residents and the capacity for local action and involvement in managing forest disturbances. Communication and interaction between resource managers and local stakeholders can facilitate the identification of management priorities and potentially reduce some of the risks associated with forest disturbances by insects.
The oak wilt pathogen, Ceratocystis fagacearum, may be another example of a damaging, exotic species in forest ecosystems in the United States. Though C. fagacearum has received much research attention, the origin of the fungus is unknown. The pathogen may have been endemic at a low incidence until increased disturbances, changes in land use, and forest management created conditions favorable for disease epidemics. The host genus Quercus contains some relatively resistant species native to the United States, further supporting the hypothesis that the pathogen is native in origin. However, there are also many common, highly susceptible Quercus species--a characteristic typical of introduced pathogens. Most convincingly, studies have shown that the known populations of C. fagacearum have experienced a severe genetic bottleneck that can only be explained by a single introduction. The weight of evidence indicates that C. fagacearum is an introduced pathogen, with possible origins in Central or South America, or Mexico.
Ceratocystis fagacearum (Bretz) Hunt, the oak wilt pathogen, is currently causing massive losses of semievergreen live oaks (Quercus fusiformis Small and Q. virginiana Mill.) in central Texas. Given the relatively limited oak mortality caused by C. fagacearum in the deciduous forests of the North Central, Midwestern, and Mid-Atlantic United States, this Texas epidemic was not anticipated. The intensity of oak wilt in Texas is attributed to a number of factors related to host characteristics and the ability of the pathogen to adapt to limiting environmental conditions. Oak wilt management in semievergreen oaks requires considerable revision of the control techniques previously designed for deciduous oaks. The Texas oak wilt epidemic provides a new perspective from which to evaluate questions concerning oak wilt, including the origins of the pathogen as well as the potential for future losses in unaffected oak forests.
In the southwestern United States, local weed management programs are increasingly important in weed prevention and control; however, little is known about the effectiveness of different local approaches to weed management. We surveyed coordinators of 53 local weed management programs in Arizona, Colorado, New Mexico, and Utah to determine how 4 key program attributes (interagency coordination, volunteer participation, regulatory authority and enforcement, and the state in which the program was located) were related with 4 performance measures: weed control, public education and outreach, weed monitoring, and integrated weed management. Based on the responses of 42 program coordinators (79%) we found that 1) weed programs that coordinated their activities with other organizations and those with citizen volunteers conducted more monitoring, but programs that did not coordinate or use volunteers treated more of their infested acreage; 2) programs that used a light-handed regulatory approach conducted more weed control than those with more punitive enforcement regimes or no enforcement authority; and 3) Colorado programs conducted more outreach and education than did programs in the other 3 states. Thus, although volunteer involvement and interagency coordination contributed to the performance of the local weed programs studied, particularly in monitoring, they have not compensated for the lack of locally enforceable weed regulations or adequate funding. Successful weed management in southwestern United States will require adequately funded, locally adapted approaches supported by locally enforceable weed regulations.
Introduced species represent an accelerated global change, and current efforts to manage them, though effective in particular situations, are not controlling the general problem. In the US, this failure is the result of insufficient policy, inadequate research and management funding, and gaps in scientific knowledge. Comparative policy analysis is urgently needed; the main US shortcoming is the absence of a coherent set of policies to address the entire issue, rather than individual invaders. Deliberate introductions should be more stringently regulated and risk assessments must become more predictive. Monitoring and attempts to identify new invasions (both deliberate and inadvertent) are technically feasible but not sufficiently funded and coordinated. Techniques to manage established invaders have often succeeded, but have been hamstrung by inconsistent funding. All of these problems could be improved by more fundamental research, ranging from basic natural history and simple advances in control technologies to more sophisticated ecological modeling and remote sensing techniques.
Control of biological invasions depends on the collective decisions of resource managers across invasion zones. Regions with high land-use diversity, which we refer to as "management mosaics", may be subject to severe invasions, for two main reasons. First, as land becomes increasingly subdivided, each manager assumes responsibility for a smaller portion of the total damages imposed by invasive species; the incentive to control invasives is therefore diminished. Secondly, managers opting not to control the invasion increase control costs for neighboring land managers by allowing their lands to act as an invader propagule source. Coordination among managers can help mitigate these effects, but greater numbers - and a wider variety of land managers occupying a region hinder collective action. Here, we discuss the challenges posed by management mosaics, using a case study of the yellow starthistle (Centaurea solstitialis) invasion in the Sierra Nevada foothills of California. We suggest that the incorporation of management mosaic dynamics into invasive species research and management is essential for successful control of invasions, and provide recommendations to address this need.
Summary • Humans have traded and transported alien species for millennia with two notable step-changes: the end of the Middle Ages and beginning of the Industrial Revolution. However, in recent decades the world has entered a new phase in the magnitude and diversity of biological invasions: the Era of Globalization. This Special Profile reviews the links between the main drivers of globalization and biological invasions and examines state-of-the-art approaches to pathway risk assessment to illustrate new opportunities for managing invasive species. • Income growth is a primary driver of globalization and a clear association exists between Gross Domestic Product and the richness of alien floras and faunas for many regions of the world. In many cases, the exposure of these economies to trade is highlighted by the significant role of merchandise imports in biological invasions, especially for island ecosystems. • Post-1950, technical and logistic improvements have accelerated the ease with which commodities are transported across the globe and hindered the traceability of goods and the ease of intercepting pests. New sea, land and air links in international trade and human transport have established novel pathways for the spread of alien species. Increasingly, the science advances underpinning invasive species management must move at the speed of commerce. • Increasing transport networks and demand for commodities have led to pathway risk assessments becoming the frontline in the prevention of biological invasions. The diverse routes of introduction arising from contaminant, stowaway, corridor and unaided pathways, in both aquatic and terrestrial biomes are complex. Nevertheless, common features enable comparable approaches to risk assessment. By bringing together spatial data on climate suitability, habitat availability and points of entry, as well a demographic models that include species dispersal (both natural and human-mediated) and measures of propagule pressure, it is possible to generate risk maps highlighting potential invasion hotspots that can inform prevention strategies. • Synthesis and applications. To date, most attempts to model pathways have focused on describing the likelihood of invader establishment. Few have modelled explicit management strategies such as optimal detection and inspection strategies and assessments of the effectiveness of different management measures. A future focus in these areas will ensure research informs response.
Abstract “Biological invasions” are now recognized as the cause of significant ecological and economic damage. They also raise a series of less visible social issues. Management of invasive species is often a political process raising questions such as who decides which organisms are to be managed, and who benefits or is affected by different management techniques. In a rural region of northern California, the proposed use of herbicides on spotted knapweed sparked an intense social controversy. This research uses participant observation, interviews, and archival material to understand how members of the Karuk Tribe of California, the non-Indian community, and the U.S. Forest Service developed different perceptions of safety and risk regarding herbicide use. I describe interconnected factors that frame the interpretation of risk: institutional trust, proximity to exposure, gender, and race. Gender and race, in turn, form the basis of anti-herbicide mobilization. The larger sociological question highlighted is, who pays the price for species invasions? Use of herbicides on invasive species is increasing. Many people who face increased exposure to herbicides are members of racial minority groups. When the poor or racial minorities face disproportionate exposure, differences in risk perception become matters of environmental justice. This paper discusses the broader social implications of differences in risk perception among communities and land managers.
Biotic resistance describes the ability of resident species in a community to reduce the success of exotic invasions. Although resistance is a well-accepted phenomenon, less clear are the processes that contribute most to it, and whether those processes are strong enough to completely repel invaders. Current perceptions of strong, competition-driven biotic resistance stem from classic ecological theory, Elton's formulation of ecological resistance, and the general acceptance of the enemies-release hypothesis. We conducted a meta-analysis of the plant invasions literature to quantify the contribution of resident competitors, diversity, herbivores and soil fungal communities to biotic resistance. Results indicated large negative effects of all factors except fungal communities on invader establishment and performance. Contrary to predictions derived from the natural enemies hypothesis, resident herbivores reduced invasion success as effectively as resident competitors. Although biotic resistance significantly reduced the establishment of individual invaders, we found little evidence that species interactions completely repelled invasions. We conclude that ecological interactions rarely enable communities to resist invasion, but instead constrain the abundance of invasive species once they have successfully established.
We used historical data to parameterize species-accumulation models relating international trade to the establishment rates of nonindigenous species in the United States over the past century. We then coupled these relationships with published trade forecasts to predict future invasion rates for insects, plant pathogens, and mollusks. Relationships between the accumulation of non-native species and merchandise imports were reasonably described by log-log and log-linear species-area models and Michaelis-Menten accumulation functions. However, the latter two models produced markedly better fits. When coupled with projected trade forecasts, the log-linear species-area model predicted 16–24% taxon-specific increases in the number of nonindigenous species established in the United States from 2000 to 2020. The Michaelis-Menten model predicted much lower 3–6% increases, but even this meant 115 new insect species and 5 new plant pathogens. These results suggest that the ecological and economic costs associated with human-caused biological invasions may continue to rise substantially over the coming decades.
Invasive alien species (IAS) exact large biodiversity and economic costs and are a significant component of human-induced,
global environmental change. Previous studies looking at the variation in alien species across regions have been limited geographically
or taxonomically or have not considered economics. We used a global invasive species database to regress IAS per-country on
a suite of socioeconomic, ecological, and biogeographical variables. We varied the countries included in the regression tree
analyses, in order to explore whether certain outliers were biasing the results, and in most of the cases, merchandise imports
was the most important explanatory variable. The greater the degree of international trade, the higher the number of IAS.
We also found a positive relationship between species richness and the number of invasives, in accord with other investigations
at large spatial scales. Island status (overall), country area, latitude, continental position (New World versus Old World)
or other measures of human disturbance (e.g., GDP per capita, population density) were not found to be important determinants
of a country’s degree of biological invasion, contrary to previous studies. Our findings also provide support to the idea
that more resources for combating IAS should be directed at the introduction stage and that novel trade instruments need to
be explored to account for this environmental externality.
Oak wilt, caused by the invasive fungal pathogen Ceratocystis fagacearum (Bretz) Hunt, is a serious and fatal disease of oaks, Quercus spp., with red oaks (section Lobatae) generally being more susceptible than white oaks (section Quercus). Oak wilt was first recognized in North America in 1944 and has since been confirmed in 24 eastern, midwestern, and southern states. The purpose of this paper is to review relevant literature on the efficacy of oak wilt treatment options. Root disruption, sanitation, and chemical control methods have been used most often to manage the disease. Root disruption has primarily focused on severing root grafts between oaks. Sanitation has focused on removal and proper disposal of potential spore-producing trees. Chemical control has focused on the use of systemic triazole fungicides. Efficacy of treatments can vary significantly, for example from 54% to 100% for root graft barriers. Educational programs can increase prevention efforts, detection, compliance with recommended management methods, and overall efficacy. Our review confirms that management programs should address underground and overland spread and include an educational component.
Foreword - Larry Culpepper Introduction - William L Miller and Benjamin F Crabtree PART ONE: OVERVIEW OF QUALITATIVE RESEARCH METHODS Primary Care Research - William L Miller and Benjamin F Crabtree A Multimethod Typology and Qualitative Roadmap PART TWO: DISCOVERY: DATA COLLECTION STRATEGIES Sampling in Qualitative Inquiry - Anton J Kuzel Participant Observation - Stephen P Bogdewic Key Informant Interviews - Valerie J Gilchrist PART THREE: INTERPRETATION: STRATEGIES OF ANALYSIS A Template Approach to Text Analysis - Benjamin F Crabtree and William L Miller Developing and Using Codebooks Grounded Hermeneutic Research - Richard B Addison Computer Management Strategies for Text Data - Alfred O Reid Jr PART FOUR: SPECIAL CASES OF ANALYSIS Approaches to Audio and Video Tape Analysis - Moira Stewart Interpreting the Interactions Between Patients and Physicians Historical Method - Miguel Bedolla A Brief Introduction Philosophic Approaches - Howard Brody PART FIVE: PUTTING IT ALL TOGETHER: COMPLETED STUDIES A Qualitative Study of Family Practice Physician Health Promotion Activities - Dennis G Willms, Nancy A Johnson and Norman A White Doctor-Caregiver Relationships - David Morgan An Exploration Using Focus Groups PART SIX: SUMMARY Qualitative Research - Ian McWhinney et al Perspectives on the Future
The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management.
Ceratocystis fagacearum (Bretz) Hunt, the oak wilt pathogen, is currently causing massivel osses of semievergreen live oaks (Quercus fusiformis Small and Q. virginiana Mill.) in central Texas. Given the relatively limited oak mortality caused by C. fagacearum in the deciduous forests of the North Central, Midwestern, and Mid-Atlantic United States, this Texas epidemic was not anticipated. The intensity of oak wilt in Texas is attributed to a number of factors related to host characteristics and the ability of the pathogen to adapt to limiting environmental conditions. Oak wilt management in semievergreen oaks requires considerable revision of the control techniques previously designed for deciduous oaks. The Texas oak wilt epidemic provides a new perspective from which to evaluate questions concerning oak wilt, including the origins of the pathogen as well as the potential for future losses in unaffected oak forests.
In this paper, we will examine some approximations to the multivariate hypergeometric distribution by continuous random variables. The continuous random variables will be chosen so as to have the same range of variation, means, variances and covariances as their discrete counterparts. We then show how these approximations can be used in testing hypotheses about the parameters of the multivariate hypergeometric distribution.
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