Gender and the Automobile – An Analysis of Non-work Service Trips

Focusing on individual motorists in car-owning households in Germany, this analysis econometrically investigates the determinants of automobile travel for non-work service activities against the backdrop of two questions: 1) Does gender play a role in determining the probability of car use and the distance driven? 2) If so, how is this role mitigated or exacerbated by other socioeconomic attributes of the individual and the household in which they reside? Drawing on a panel of data collected between 1996 and 2003, we specify Heckman’s sample selection model to control for biases that could otherwise arise from the existence of unobservable variables that determine both the discrete and continuous choices pertaining to car use.The results indicate that although women,on average, undertake more non-work travel than men, they undertake less of such travel by car, implying a greater reliance on other modes. Moreover, employment status, age, the number of children, automobile availability, and the proximity to public transit are all found to have significantly different effects on the probability of non-work car travel between men and women, but – with the exception of automobile availability – not on the distance driven.Taken together, these results suggest that policies targeted at reducing automobile dependency and associated negative externalities such as congestion are unlikely to have uniform effects across the sexes, findings having implications for both policy evaluation as well as travel demand forecasting.Automobile travel, gender, Heckman model, Monte Carlo simulation

ASSESSING THE JOINT INFLUENCE OF ECOLOGICAL AND SOCIOECONOMIC DETERMINANTS OF INCREASES IN THE BUILT-ENVIRONMENT: A STUDY OF TRENDS IN CENTRAL NORTH CAROLINA

This paper advances an empirical model assessing how, over both time and space, changes in land-use respond to changing economic and ecological conditions. Focusing on Central North Carolina, a region that has undergone extensive changes in forest cover and agricultural lands over the past two decades, landscape dynamics are modeled by exploiting a spatial database that links several satellite images spanning the years 1975-1999 to a suite of socioeconomic, institutional and GIS-created explanatory variables.Environmental Economics and Policy, Land Economics/Use,

Cities and Satellites: Spatial Effects and Unobserved Heterogeneity in the Modeling of Urban Growth

The confluence of factors driving urban growth is highly complex, resulting from a combination of ecological and social determinants that co-evolve over time and space. Identifying these factors and quantifying their impact necessitates models that capture both why urbanization happens as well as where and when it happens. Using a database that links five satellite images spanning 1976–2001 to a suite of socioeconomic, ecological and GIS created explanatory variables, this study develops a spatial-temporal model of the determinants of built-up area across a 25,900 square kilometer swath across central North Carolina. Extensive conversion of forest and agricultural land over the last decades is modeled using the complementary log-log derivation of the proportional hazards model, thereby affording a means for modeling continuous- time landscape change using discrete-time satellite data. To control for unobserved heterogeneity, the model specification includes an error component that is Gamma distributed. Results confirm the hypothesis that the landscape pattern surrounding a pixel has a major influence on the likelihood of its conversion and, moreover, that the omission of external spatial effects can lead to biased inferences regarding the influence of other covariates, such as proximity to road. Cartographic and nonparametric validation exercises illustrate the utility of the model for policy simulation.Urban growth, landscape pattern, satellite imagery, hazard model,North Carolina

Land conversion and market equilibrium

We specify a system of equations that fully reflects the supply and demand sides of the market for agricultural open space at equilibrium. Although simple, the system is exceedingly flexible and allows for household and parcel heterogeneity. We derive an empirical model directly from the structural equations and contrast this using a simulated landscape with the econometric specification most often found in the literature. We then show how the model can be used to project land-use change into the future and for policy simulation. Finally, we use the model to examine the impact of common land conservation policies in Europe

Past role and future outlook of the Conservation Reserve Program for supporting honey bees in the Great Plains

Human dependence on insect pollinators continues to grow even as pollinators face global declines. The Northern Great Plains (NGP), a region often referred to as America’s last honey bee (Apis mellifera) refuge, has undergone rapid land-cover change due to cropland expansion and weakened land conservation programs. We conducted a trend analysis and estimated conversion rates of Conservation Reserve Program (CRP) enrollments around bee apiaries from 2006 to 2016 and developed models to identify areas of habitat loss. Our analysis revealed that NGP apiaries lost over 53% of lands enrolled in the CRP, and the rate of loss was highest in areas of high apiary density. We estimated over 163,000 ha of CRP lands in 2006 within 1.6 km of apiaries was converted to row crops by 2012. We also evaluated how alternative scenarios of future CRP acreage caps may affect habitat suitability for supporting honey bee colonies. Our scenario revealed that a further reduction in CRP lands to 7.7 million ha nationally would reduce the number of apiaries in the NGP that meet defined forage criteria by 28% on average. Alternatively, increasing the national cap to 15 million ha would increase the number of NGP apiaries that meet defined forage criteria by 155%. Our scenarios also show that strategic placement of CRP lands near existing apiaries increased the number of apiaries that meet forage criteria by 182%. Our research will be useful for informing the potential consequences of future US farm bill policy and land management in the epicenter of the US beekeeping industry

Persistence and quality of vegetation cover in expired Conservation Reserve Program fields

For nearly 40 years, the Conservation Reserve Program (CRP) has implemented practices to reduce soil erosion, improve water quality, and provide habitat for wildlife and pollinators on highly erodible cropland in the United States. However, an approximately 40,470 ha (10 million acres) decline in enrolled CRP land over the last decade has greatly reduced the program\u27s environmental benefits. We sought to assess the program\u27s enduring benefits in the central and western United States by (1) determining the proportion of fields that persist in CRP cover after contracts expired, (2) identifying the type of agricultural production that CRP fields shift to after contract expiration, (3) comparing the vegetation characteristics of expired CRP fields that are persisting in CRP-type cover with enrolled CRP fields, and (4) identifying differences in management activities (e.g., haying, grazing) between expired and enrolled CRP fields. We conducted edge-of-field vegetation cover surveys in 1092 CRP fields with contracts that expired ≥3 years prior and 1786 currently enrolled CRP fields in 14 states. We found that 41% of expired CRP fields retained at least half of their area in CRP-type cover, with significant variation in persistence among regions ranging from 19% to 84%. When expired fields retained CRP vegetation, bare ground was low in all regions and grass cover was somewhat greater than in fields with current CRP contracts, but at the expense of forb cover in some regions. Evidence of more frequent management in expired CRP fields may explain differences between active and expired CRP fields. Overall, there is clear evidence that CRP-type cover frequently persists and provides benefits for more than three years after contract expiration. Retaining CRP-type cover, post-contract, is an under-recognized program benefit that persists across the central and western United States long after the initial retirement from cropland

ASSESSING THE JOINT INFLUENCE OF ECOLOGICAL AND SOCIOECONOMIC DETERMINANTS OF INCREASES IN THE BUILT-ENVIRONMENT: A STUDY OF TRENDS IN CENTRAL NORTH CAROLINA

This paper advances an empirical model assessing how, over both time and space, changes in land-use respond to changing economic and ecological conditions. Focusing on Central North Carolina, a region that has undergone extensive changes in forest cover and agricultural lands over the past two decades, landscape dynamics are modeled by exploiting a spatial database that links several satellite images spanning the years 1975-1999 to a suite of socioeconomic, institutional and GIS-created explanatory variables

Gender and the Automobile: Analysis of Nonwork Service Trips

With a focus on individual motorists in car-owning households in Germany, this analysis econometrically investigates the determinants of automobile travel for nonwork service activities against the backdrop of two questions: (a) Does gender play a role in determining the probability of car use and the distance driven? and (b) If so, how is this role mitigated or exacerbated by other socioeconomic attributes of the individual and the household in which he or she resides? Drawing on a panel of data collected between 1996 and 2003, Heckman’s sample selection model is specified to control for biases that otherwise could arise from the existence of unobservable variables that determine both the discrete and the continuous choices pertaining to car use. The results indicate that although women, on average, undertake more nonwork travel than men, they undertake less such travel by car, implying a greater reliance on other modes. Moreover, employment status, age, the number of children, automobile availability, and the proximity to public transit are all found to have significantly different effects on the probability of nonwork car travel between men and women but—with the exception of automobile availability—not on the distance driven. Taken together, these results suggest that policies targeted at reducing automobile dependency and associated negative externalities, such as congestion, are unlikely to have uniform effects across the sexes. These findings have implications for both policy evaluation and travel demand forecasting