Rural and Suburban Sprawl in the U.S. Midwest from 1940 to 2000 and Its Relation to Forest Fragmentation

Abstract:  Housing growth and its environmental effects pose major conservation challenges. We sought to (1) quantify spatial and temporal patterns of housing growth across the U.S. Midwest from 1940–2000, (2) identify ecoregions strongly affected by housing growth, (3) assess the extent to which forests occur near housing, and (4) relate housing to forest fragmentation. We used data from the 2000 U.S. Census to derive fine-scale backcasts of decadal housing density. Housing data were integrated with a 30-m resolution U.S. Geological Survey land cover classification. The number of housing units in the Midwest grew by 146% between 1940 and 2000. Spatially, housing growth was particularly strong at the fringe of metropolitan areas (suburban sprawl) and in nonmetropolitan areas (rural sprawl) that are rich in natural amenities such as lakes and forests. The medium-density housing (4–32 housing units/km²) category increased most in area. Temporally, suburban housing growth was especially high in the post-World War II decades. Rural sprawl was highest in the 1970s and 1990s. The majority of midwestern forests either contained or were near housing. Only 14.8% of the region's forests were in partial block groups with no housing. Housing density was negatively correlated with the amount of interior forest. The widespread and pervasive nature of sprawl shown by our data is cause for conservation concern. Suburban sprawl has major environmental impacts on comparatively small areas because of the high number of housing units involved. In contrast, rural sprawl affects larger areas but with less intensity because associated housing densities are lower. The environmental effects per house, however, are likely higher in the case of rural sprawl because it occurs in less-altered areas. Conservation efforts will need to address both types of sprawl to be successful.     

Beyond Biogeography: a Framework for Involving the Public in Planning of U.S. Marine Protected Areas

Abstract:  Planning of marine protected areas (MPAs) is highlighted in the conservation literature but is not explored in much detail. Many researchers acknowledge the importance of involving the public in MPA planning, but there is limited guidance on how to do this in an effective manner. I present a framework for involving the public in planning of U.S. MPAs. Derived from empirically and theoretically based research on public participation in U.S. natural resource management, this framework is composed of factors that influence the success of participatory processes: active participant involvement, complete information exchange, fair decision making, efficient administration, and positive participant interactions. Processes incorporating these factors will produce decisions that are more likely to be supported by stakeholders, meet management objectives, and fulfill conservation goals. This framework contributes to the MPA social science literature and responds to calls in the conservation literature to increase the use of social science research to inform conservation decision making.     

美国杏李园主要害虫与天敌类群间相关性分析

应用典范相关分析方法研究了美国杏李园丰要害虫与天敌间的相互关系,在未受干扰的自生园中.害虫亚系统与天敌亚系统间第一典范相关系数达到显著水平,天敌亚系统中瓢虫类、草蛉类与主要害虫蚜虫类,螨类的数量变动规律一致.而蜘蛛类与主要害虫的数最关系不密切,化防园内主要害虫与天敌间的典范相关系数均未达显著永平,这表明未受干扰的自生园和生防园内,害虫与天敌亚系统间存在着有效的数量反馈机制,天敌对害虫具有一定的自然抑制作用,而化防园内,害虫与天敌间的数量反馈机制因农药干扰而失调,生态平衡受破坏.自生园和生防园害虫与天敌主要类群间具正相关关系.害虫亚系统中,蚜虫类贡献最大,其次为山楂叶螨和李小食心虫:天敌亚系统中蜘蛛和瓢虫贡献最大,其次为瓢虫类和草蛉类,草蛉类贡献最小.说明蜘蛛类、瓢虫类与主要害虫的数量变动规律一致.而草蛉类与美国杏李园主要害虫的数量关系不密切.     

Tracking land cover change along the western edge of the U.S. Corn Belt from 1984 through 2016 using satellite sensor data: observed trends and contributing factors

The Cropland Data Layers (CDL) are high-resolution geo-referenced data products made available by the U.S. Department of Agriculture. However, the CDL lacks in its ability to be employed as a tool to identify the impact of the gradually evolving drivers of land use change, e.g., climate change, due to its limited historical depth. We implement a robust, phenology-based satellite image classification algorithm to identify historical cropland allocation in eastern South Dakota and North Dakota predating the initial CDL by 13 and 22 years, respectively. Five major land covers, i.e., corn, soybeans, wheat, alfalfa and grass (including native grass, hay and pasture) are identified using archived Landsat-5 surface reflectance data, while achieving CDL-like accuracy. The long-term rate of grassland loss during 1985–2011 is found to be significantly lower (26,781 hectares or 1.5% annually) relative to the near-term rate of grassland loss during 2006-’11 (84,545 hectares or 5.2% annually). We find similar discrepancy in regional corn expansion rates. Our value-added raster data provide opportunities for improved identification of land use drivers, whereas relying solely on the CDL’s restricted historical extent may lead to biased land use change estimates and misguide policy.     

Human drivers,biophysical changes,and climatic variation affecting contemporary cropping proportions in the northern prairie of the U.S

Grassland to cropland conversion in the northern prairie of the United States has been a topic of recent land use change studies. Within this region more corn and soybeans are grown now (2017) than in the past, but most studies to date have not examined multi-decadal trends and the synergistic web of socio-ecological driving forces involved, opting instead for short-term analyses and easily targeted agents of change. This paper examines the coalescing of biophysical and socioeconomic driving forces that have brought change to the agricultural landscape of this region between 1980 and 2013. While land conversion has occurred, most of the region’s cropland in 2013 had been previously cropped by the early 1980s. Furthermore, the agricultural conditions in which crops were grown during those three decades have changed considerably because of non-biophysical alterations to production practices and changing agricultural markets. Findings revealed that human drivers played more of a role in crop change than biophysical changes, that blending quantitative and qualitative methods to tell a more complete story of crop change in this region was difficult because of the synergistic characteristics of the drivers involved, and that more research is needed to understand how farmers make crop choice decisions.     

Hybridization,agency discretion,and implementation of the U.S. Endangered Species Act

The U.S. Endangered Species Act (ESA) requires that the “best available scientific and commercial data” be used to protect imperiled species from extinction and preserve biodiversity. However, it does not provide specific guidance on how to apply this mandate. Scientific data can be uncertain and controversial, particularly regarding species delineation and hybridization issues. The U.S. Fish and Wildlife Service (FWS) had an evolving hybrid policy to guide protection decisions for individuals of hybrid origin. Currently, this policy is in limbo because it resulted in several controversial conservation decisions in the past. Biologists from FWS must interpret and apply the best available science to their recommendations and likely use considerable discretion in making recommendations for what species to list, how to define those species, and how to recover them. We used semistructured interviews to collect data on FWS biologists’ use of discretion to make recommendations for listed species with hybridization issues. These biologists had a large amount of discretion to determine the best available science and how to interpret it but generally deferred to the scientific consensus on the taxonomic status of an organism. Respondents viewed hybridization primarily as a problem in the context of the ESA, although biologists who had experience with hybridization issues were more likely to describe it in more nuanced terms. Many interviewees expressed a desire to continue the current case‐by‐case approach for handling hybridization issues, but some wanted more guidance on procedures (i.e., a “flexible” hybrid policy). Field‐level information can provide critical insight into which policies are working (or not working) and why. The FWS biologists’ we interviewed had a high level of discretion, which greatly influenced ESA implementation, particularly in the context of hybridization.