Influence of seasonality and vegetation type on suburban microclimates

Urbanization is responsible for some of the fastest rates of land-use change around the world, with important consequences for local, regional, and global climate. Vegetation, which represents a significant proportion of many urban and suburban landscapes, can modify climate by altering local exchanges of heat, water vapor, and CO₂. To determine how distinct urban forest communities vary in their microclimate effects over time, we measured stand-level leaf area index, soil temperature, infrared surface temperature, and soil water content over a complete growing season at 29 sites representing the five most common vegetation types in a suburban neighborhood of Minneapolis–Saint Paul, Minnesota. We found that seasonal patterns of soil and surface temperatures were controlled more by differences in stand-level leaf area index and tree cover than by plant functional type. Across the growing season, sites with high leaf area index had soil temperatures that were 7°C lower and surface temperatures that were 6°C lower than sites with low leaf area index. Site differences in mid-season soil temperature and turfgrass ground cover were best explained by leaf area index, whereas differences in mid-season surface temperature were best explained by percent tree cover. The significant cooling effects of urban tree canopies on soil temperature imply that seasonal changes in leaf area index may also modulate CO₂ efflux from urban soils, a highly temperature-dependent process, and that this should be considered in calculations of total CO₂ efflux for urban carbon budgets. Field-based estimates of percent tree cover were found to better predict mid-season leaf area index than satellite-derived estimates and consequently offer an approach to scale up urban biophysical properties.     

Potential impacts of emerald ash borer invasion on biogeochemical and water cycling in residential landscapes across a metropolitan region

Trees provide important ecological services in cities, yet the vulnerability of the urban forest to massive tree losses from pest outbreaks could threaten those services, with unknown environmental consequences. The outbreak of emerald ash borer is an imminent threat to the ash population in North America. In the Minneapolis?CSaint Paul, Minnesota, metropolitan area, ash trees are present in 50?% of residential landscapes in Ramsey and Anoka Counties. We used a large survey of household activities, a tree inventory, a Household Flux Calculator accounting tool, and a set of annual evapotranspiration measurements, to quantify the current carbon, nitrogen, and phosphorus storage in ash trees, the cycling of these elements, and the total evapotranspiration from ash trees in residential areas in the metropolitan region. Ash represented 6?% of the trees in residential areas and the removal of the entire ash population would correspondingly reduce net primary production and carbon sequestration by only a few percent and would have negligible effects on losses of nitrogen and phosphorus from residential landscapes. Similarly, the effects of ash loss on the hydrologic cycle would be minimal and would depend largely on management choices for the ground currently underneath ash tree canopies. Overall, the percentage change in biogeochemical and hydrological fluxes corresponded closely with the percent of the total urban tree population that was represented by ash, suggesting that areas with higher densities of ash would experience correspondingly larger effects. A hypothetical tree replacement scenario with similar broadleaf species was determined to be likely to re-establish the original biogeochemical and hydrological conditions once the replacement trees reach maturity.     

Rationality for Economists?

Rationality is a complex behavioral theory that can be parsed into statements about preferences, perceptions, and process. This paper looks at the evidence on rationality that is provided by behavioral experiments, and argues that most cognitive anomalies operate through errors in perception that arise from the way information is stored, retrieved, and processed, or through errors in process that lead to formulation of choice problems as cognitive tasks that are inconsistent at least with rationality narrowly defined. The paper discusses how these cognitive anomalies influence economic behavior and measurement, and their implications for economic analysis.     

Soviet Negotiating Behavior: A Research Design

This article discusses the Valuev circular of 1863 that placed limits on Ukrainian-language publications in the Russian Empire. It is based on extensive archival materials from RGIA in St. Petersburg. The main focus is on Petr Valuev’s intentions and the actual impact the circular had on Ukrainian publishing. Apart from the fear of Polish and Ukrainian subversion, Valuev was motivated by a long-term desire to spread the use of Russian—at least among some minority nationalities of the empire. The officially ‘provisional’ nature of the circular was Valuev’s tactic to appease the significant opposition that he anticipated within government circles against the restrictions. In actual fact, the minister intended his circular to retain its force for a long period of time. Up to the time of the Ems decree of 1876, the central bodies of censorship considered the circular binding. However, many works that violated the circular were indeed permitted and published (especially in the years 1874–1876). This is explained mainly by the corruption of one censor in Kyiv who permitted most of these publications and was ultimately dismissed.     

Aging in (Privatized) Places: Subsidized Housing Policy and Seniors

The market-based approach of delivering affordable housing has led to a net loss of traditional public housing and an increase in alternative subsidized housing options. For poor, physically frail older adult residents, subsidized housing and its associated services and support provide an important safety net. This article explores the implications and consequences of this movement for low-income seniors. Specifically, we look at the past and current housing policies, the focus on public-private partnerships, and the transition toward mixed-income communities. The article ends with suggestions for protecting vulnerable older adult populations in a market-driven arena.     

Firm-specific human capital, job matching, and turnover: evidence from major league baseball, 1900–1992

The two dominant labor market turnover hypotheses, the firm-specific human capital model (FSHCM) and the job-matching model, suggest different patterns of player mobility in major league baseball. The matching hypothesis predicts greater mobility of players in positions that require substantial team production. A better match may offer large productivity gains. Alternately, the FSHCM predicts players in positions requiring the greatest amount of teamwork will benefit from specific knowledge, making them less likely to change teams. We examine the frequency distribution of trades by player position from 1900–1992 and find the FSHCM provides the best explanation for turnover in this industry.