361 research outputs found
Public Benefits of Undeveloped Lands on Urban Outskirts: Non-Market Valuation Studies and their Role in Land Use Plans
Over the past three decades, the economics profession has developed methods for estimating the public benefits of green spaces, providing an opportunity to incorporate such information into land-use planning. While federal regulations routinely require such estimates for major regulations, the extent to which they are used in local land use plans is not clear. This paper reviews the literature on public values for lands on urban outskirts, not just to survey their methods or empirical findings, but to evaluate the role they have played--or have the potential to play-- in actual land use plans. Based on interviews with authors and representatives of funding agencies and local land trusts, it appears that academic work has had a mixed reception in the policy world. Reasons for this include a lack of interest in making academic work accessible to policy makers, emphasizing revealed preference methods which are inconsistent with policy priorities related to nonuse values, and emphasis on benefit-cost analyses. Nevertheless, there are examples of success stories that illustrate how such information can play a vital role in the design of conservation policies. Working Paper 07-2
Superfund, Hedonics, and the Scales of Environmental Justice
Environmental justice (EJ) is prominent in environmental policy, yet EJ research is plagued by debates over methodological procedures. A well-established economic approach, the hedonic price method, can offer guidance on one contentious aspect of EJ research: the choice of the spatial unit of analysis. Environmental managers charged with preventing or remedying inequities grapple with these framing problems. This article reviews the theoretical and empirical literature on unit choice in EJ, as well as research employing hedonic pricing to assess the spatial extent of hazardous waste site impacts. The insights from hedonics are demonstrated in a series of EJ analyses for a national inventory of Superfund sites. First, as evidence of injustice exhibits substantial sensitivity to the choice of spatial unit, hedonics suggests some units conform better to Superfund impacts than others. Second, hedonic estimates for a particular site can inform the design of appropriate tests of environmental inequity for that site. Implications for policymakers and practitioners of EJ analyses are discussed
Mapping recent information behavior research: an analysis of co-authorship and cocitation networks
There has been an increase in research published on information behavior in recent years, and this has been accompanied by an increase in its diversity and interaction with other fields, particularly information retrieval (HR). The aims of this study are to determine which researchers have contributed to producing the current body of knowledge on this subject, and to describe its intellectual basis. A bibliometric and network analysis was applied to authorship and co-authorship as well as citation and co-citation. According to these analyses, there is a small number of authors who can be considered to be the most productive and who publish regularly, and a large number of transient ones. Other findings reveal a marked predominance of theoretical works, some examples of qualitative methodology that originate in other areas of social science, and a high incidence of research focused on the user interaction with information retrieval systems and the information behavior of doctors
Automated valuation modelling: a specification exercise
Market value predictions for residential properties are important for investment decisions and the risk management of households, banks, and real estate developers. The increased access to market data has spurred the development and application of Automated Valuation Models (AVMs), which can provide appraisals at low cost. We discuss the stages involved when developing an AVM. By reflecting on our experience with md*immo, an AVM from Berlin, Germany, our paper contributes to an area that has not received much attention in the academic literature. In addition to discussing the main stages of AVM development, we examine empirically the statistical model development and validation step. We find that automated outlier removal is important and that a log model performs best, but only if it accounts for the retransformation problem and heteroscedasticity
Sagebrush, Greater Sage-Grouse, and the occurrence and importance of forbs
Big sagebrush (Artemisia tridentata Nutt.) ecosystems provide habitat for sagebrush-obligate wildlife species such as the Greater Sage-Grouse (Centrocercus urophasianus). The understory of big sagebrush plant communities is composed of grasses and forbs that are important sources of cover and food for wildlife. The grass component is well described in the literature, but the composition, abundance, and habitat role of forbs in these communities is largely unknown. Our objective was to synthesize information about forbs and their importance to Greater Sage-Grouse diets and habitats, how rangeland management practices affect forbs, and how forbs respond to changes in temperature and precipitation. We also sought to identify research gaps and needs concerning forbs in big sagebrush plant communities. We searched for relevant literature including journal articles and state and federal agency reports. Our results indicated that in the spring and summer, Greater Sage-Grouse diets consist of forbs (particularly species in the Asteraceae family), arthropods, and lesser amounts of sagebrush. The diets transition to sagebrush in fall and winter. Forbs provide cover for Greater Sage-Grouse individuals at their lekking, nesting, and brood-rearing sites, and the species has a positive relationship with arthropod presence. The effect of grazing on native forbs may be compounded by invasion of nonnative species and differs depending on grazing intensity. The effect of fire on forbs varies greatly and may depend on time elapsed since burning. In addition, chemical and mechanical treatments affect annual and perennial forbs differently. Temperature and precipitation influence forb phenology, biomass, and abundance differently among species. Our review identified several uncertainties and research needs about forbs in big sagebrush ecosystems. First, in many cases the literature about forbs is reported only at the genus or functional type level. Second, information about forb composition and abundance near lekking sites is limited, despite the fact that lekking sites are an important center of Greater Sage-Grouse activity. Third, there is little published literature on the relationship between forbs and precipitation and between forbs and temperature, thereby limiting our ability to understand potential responses of forbs to climate change. While there is wide agreement among Greater Sage-Grouse biologists that forbs are an important habitat component, our knowledge about the distribution and environmental responses of forb species in big sagebrush plant communities is limited. Our work for the first time synthesizes the current knowledge regarding forbs in sagebrush ecosystems and their importance for Greater Sage-Grouse and identifies additional research needs for effective conservation and management.Los ecosistemas de artemisa (Artemisia tridentata Nutt) son el hábitat de especies silvestres como el urogallo de las artemisas (Centrocercus urophasianus). El sotobosque de las comunidades de plantas de artemisa grandes se compone de pastos y malezas que son importantes fuentes de cobertura y alimento para la fauna. El componente de pastos está bien descrito en la literatura, pero hay un vacío en el conocimiento de la composición, abundancia y el papel que juega el hábitat de especies herbáceas en estas comunidades. Nuestro objetivo fue sintetizar información sobre las plantas herbáceas y su importancia para las dietas y los hábitats de los urogallos, cómo las prácticas de manejo de los pastizales afectan a las plantas herbáceas y cómo éstas responden a los cambios de temperatura y precipitación. También intentamos identificar las deficiencias en las investigaciones y las necesidades de las plantas herbáceas en comunidades de plantas de artemisa grandes. Realizamos búsquedas generales en la literatura relevante, incluyendo artículos en revistas e informes gubernamentales y reportes de agencias federales. Nuestros resultados indican que, durante la primavera y el verano, la dieta de los urogallos consiste de hierbas, en particular de especies de la familia Asteraceae, artrópodos y, en menor medida, artemisas. Su dieta cambió a artemisas durante el otoño y el invierno. Las plantas herbáceas ofrecen cobertura a los urogallos en sus áreas de lek, anidación y lugares de cría, y tienen una relación positiva con la presencia de artrópodos. Los efectos del pastoreo en las plantas herbáceas nativas pueden agravarse con la invasión de especies no nativas, y difieren dependiendo de la intensidad del pastoreo. Los efectos del fuego en las plantas herbáceas son muy variables, y pueden depender del tiempo transcurrido desde la quema. Además, los tratamientos químicos y mecánicos afectan a las plantas herbáceas anuales y perennes de manera diferente. La temperatura y la precipitación influencian la fenología, la biomasa y la abundancia de las herbáceas de manera diferente entre especies. Nuestra revisión identificó varias incertidumbres y la necesidad de estudiar las plantas herbáceas en los ecosistemas de artemisa. En primer lugar, en muchos casos, la literatura informa sólo a nivel de género o funcional sobre las herbáceas. En segundo lugar, la información sobre la composición y la abundancia de las herbáceas cerca de áreas de lek es limitada, a pesar de que los sitios de lek son una parte importante de la actividad del urogallo. En tercer lugar, tenemos poca literatura sobre la relación entre las plantas herbáceas y las precipitaciones, así como de las herbáceas y la temperatura, lo cual limita nuestra capacidad para entender las posibles respuestas de las herbáceas al cambio climático. Nuestra conclusión general es que, si bien existe un amplio consenso entre los biólogos sobre que las herbáceas son un componente importante en el hábitat del urogallo, nuestro conocimiento sobre la distribución y las respuestas ambientales de las especies de plantas herbáceas en las comunidades de grandes plantas de artemisa es limitado. Nuestro trabajo sintetiza, por primera vez, el conocimiento actual con respecto a las plantas herbáceas en los ecosistemas de artemisa y su importancia para el urogallo, al mismo tiempo que identifica la necesidad de continuar investigando para encontrar un manejo y conservación eficaces
Belo Monte Dam impacts: Protagonism of local people in research and monitoring reveals ecosystem service decay in Amazonian flooded vegetation
Effects of season and reproductive state on lipid intake and fatty acid composition of gastrointestinal tract contents in the European hare
We investigated lipid content and fatty acid (FA) composition of gastrointestinal tract contents in free-living, herbivorous European hares (Lepus europaeus). Mean crude fat content in hare stomachs and total gastrointestinal (GI) tracts was higher than expected for typical herbivore forages and peaked in late fall when hares massively deposited body fat reserves. Changes of FA proportions in different parts of the GI-tract indicated a highly preferential absorption of polyunsaturated fatty acids (PUFA). A further reduction of PUFA content in the caecum, along with the appearance of odd-chained FAs in caecum, caecotrophes, and colon content, pointed to a biohydrogenation of PUFA in the hare’s hindgut. GI-tract contents showed significant seasonal changes in their FA composition. Among PUFA, α-linolenic acid peaked in spring while linoleic acid was predominant in late summer and fall, which probably reflected changes in the plant composition of forage. However, independent of seasonal changes, GI-tracts of lactating females showed a significantly (+33%) higher content of linoleic acid, a FA that is known to increase reproductive performance in European hares. This finding suggests that lactating females actively selected dietary plants rich in linoleic acid, a PUFA that may represent a limited resource for European hares
The Opportunity Cost of the Conservation Reserve Program: A Kansas Land Example
The effects of the Conservation Reserve Program (CRP) on farmland values is investigated using a set of parcel-level data for land sales in Kansas over the period 1998 to 2014. The sales data are used to estimate a hedonic model of land values that allows for the opportunity cost of CRP enrollment to vary across space and time. Factors impacting the opportunity costs include the relative productivity of land, returns to farming, and the time remaining under the CRP contracts. We find that the discount associated with having land under CRP contract averages 7%
Episodic Occurrence of Favourable Weather Constrains Recovery of a Cold Desert Shrubland After Fire
Key to the long-term resilience of dryland ecosystems is the recovery of foundation plant species following disturbance. In ecosystems with high interannual weather variability, understanding the influence of short-term environmental conditions on establishment of foundation species is essential for identifying vulnerable landscapes and developing restoration strategies. We asked how annual environmental conditions affect post-fire establishment of Artemisia tridentata, a shrub species that dominates landscapes across much of the western United States, and evaluated the influence of episodic establishment on population recovery. We collected A. tridentata stem samples from 33 plots in 12 prescribed fire sites that burned 8–11 years before sampling. We determined individual establishment years using annual growth rings. We measured seasonal soil environmental conditions at the study sites and asked if these conditions predicted annual establishment density. We then evaluated whether establishment patterns could be predicted by site-level climate or dominant subspecies. Finally, we tested the effect of the magnitude and frequency of post-fire establishment episodes on long-term population recovery. Annual post-fire recruitment of A. tridentata was driven by the episodic availability of spring soil moisture. Annual establishment was highest with wetter spring soils (relative influence [RI] = 19.4%) and later seasonal dry-down (RI = 11.8%) in the year of establishment. Establishment density declined greatly 4 to 5 years after fire (RI = 17.1%). Post-fire establishment patterns were poorly predicted by site-level mean climate (marginal R2 ≤ 0.18) and dominant subspecies (marginal R2 ≤ 0.43). Population recovery reflected the magnitude, but not the frequency, of early post-fire establishment pulses. Post-fire A. tridentata density and cover (measured 8–11 years after fire) were more strongly related to the magnitude of the largest establishment pulse than to establishment frequency, suggesting that population recovery may occur with a single favourable establishment year. Synthesis and applications. This study demonstrates the importance of episodic periods of favourable weather for long-term plant population recovery following disturbance. Management strategies that increase opportunities for seed availability to coincide with favourable weather conditions, such as retaining unburned patches or repeated seeding treatments, can improve restoration outcomes in high-priority areas
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