Valuing the benefits of the urban forest: a spatial hedonic approach

This paper measures the benefits of the urban forest by examining its effect on housing prices. A Geographic Information System is used to develop a measure of the urban forest, the Normalised Difference Vegetation Index, from satellite imagery and to construct other variables from a variety of sources. Spatial hedonic housing price models for the Indianapolis/Marion County area are estimated. The models indicate that greener vegetation around a property has a positive, significant effect on housing price, holding everything else constant. This effect is dominated by measures at the neighborhood level. These findings indicate that property owners value the urban forest, at least in part, by the premium they pay to live in neighborhoods with greener, denser vegetation. These findings also indicate that public action to maintain and enhance the urban forest may be warranted. Planners and urban foresters can use these findings to inform public and policy debates over urban forestry programs and proposals.     

The implicit price of urban public parks and greenways: a spatial-contextual approach

This paper examines the value residents place on public parks in a mid-sized urban area. The analysis makes a direct contribution to the literature by examining the extent to which spatial and neighbourhood context is related to the house price premium or discount associated with public recreational opportunities, natural resource areas and urban greenways. The analysis shows that the value of public parks and greenways varies across space, neighbourhood context and park type. Community area fixed-effects are included to bolster the findings. The findings indicate that park and greenway investment should be planned and managed contextually in urban areas. Park planners can use these findings to inform public policy debates over park investment and, perhaps, support efforts focused on comprehensive neighbourhood planning.     

Validation of the in vitro gastrointestinal (IVG) method to estimate relative bioavailable lead in contaminated soils

The effect of the dosing vehicle (e.g., dough) on the ability of an in vitro gastrointestinal (IVG) method to predict relative bioavailable Pb associated with soil ingestion was evaluated. Bioaccessible Pb determined by the IVG method was compared with relative bioavailable Pb measured from dosing trials using juvenile swine for 18 contaminated soils ranging from 1270 to 14200 mg Pb kg(-1). Bioaccessible Pb was measured in the IVG gastric extraction (GE) and intestinal extraction (IE) solutions. Mean bioaccessible Pb values were 32.2% for GE without dough, 23.0% for GE with dough, 1.06% for IE without dough, and 0.56% for IE with dough. It is possible that phytic acid associated with the dough addition decreased bioaccessible Pb. In vivo relative bioavailable Pb ranges for different swine tissues were 1 to 87% for blood, 0 to 110% for liver, 1 to 124% for kidney, and 0.04 to 94% for bone. Strong linear relationships between IVG GE Pb with dough (r > 0.76, P < 0.0002), IVG IE Pb with dough (r > 0.56, P < 0.015), and IVG GE Pb without dough (r > 0.81, P < 0.0001) and in vivo bioavailable Pb as estimated with blood, kidney, liver, and bone were found. Inexpensive in vitro methods may be useful in providing an estimate of the variability in relative bioavailable Pb at a single study site. The IVG method can be used to estimate relative bioavailable Pb, As, and Cd in contaminated soil.     

Soil characteristics and phosphorus level effect on phosphorus loss in runoff

The loss of phosphorus (P) in runoff from agricultural soils may accelerate eutrophication in lakes and streams as well as degrade surface water quality. Limited soil specific data exist on the relationship between runoff P and soil P. This study investigated the relationship between runoff dissolved reactive phosphorus (DRP) and soil P for three Oklahoma benchmark soils: Richfield (fine, smectitic, mesic Aridic Argiustoll), Dennis (fine, mixed, active, thermic Aquic Argiudoll), and Kirkland (fine, mixed, superactive, thermic Udertic Paleustoll) series. These soils were selected to represent the most important agricultural soils in Oklahoma across three major land resource areas. Surface soil (0-15 cm) was collected from three designated locations, treated with diammonium phosphate (18-46-0) to establish a wide range of water-soluble phosphorus (WSP) (3.15-230 mg kg(-1)) and Mehlich-3 phosphorus (M3P) (27.8-925 mg kg(-1)). Amended soils were allowed to reach a steady state 210 d before simulated rainfall (75 mm h(-1)). Runoff was collected for 30 min from bare soil boxes (1.0 x 0.42 m and 5% slope) and analyzed for DRP and total P. Soil samples collected immediately before rainfall simulation were analyzed for the following: M3P, WSP, ammonium oxalate P saturation index (PSI(ox)), water-soluble phosphorus saturation index (PSI(WSP)), and phosphorus saturation index calculated from M3P and phosphorus sorption maxima (P(sat)). The DRP in runoff was highly related (p < 0.001) to M3P for individual soil series (r2 > 0.92). Highly significant relationships (p < 0.001) were found between runoff DRP and soil WSP for the individual soil series (r2 > 0.88). Highly significant relationships (p < 0.001) existed between DRP and different P saturation indexes. Significant differences (p < 0.05) among the slopes of the regressions for the DRP-M3P, DRP-WSP, DRP-PSI(ox), DRP-PSI(WSP), and DRP-P(sat) relationships indicate that the relationships are soil specific and phosphorus management decisions should consider soil characteristics.     

IMPACTS OF A SEVERE SUSTAINED DROUGHT ON COLORADO RWER WATER RESOURCES1

ABSTRACT: The impacts of a severe sustained drought on Colorado River system water resources were investigated by simulating the physical and institutional constraints within the Colorado River Basin and testing the response of the system to different hydrologic scenarios. Simulations using Hydrosphere's Colorado River Model compared a 38-year severe sustained drought derived from 500 years of reconstructed streamflows for the Colorado River basin with a 38-year streamflow trace extracted from the recent historic record. The impacts of the severe drought on streamflows, water allocation, storage, hydropower generation, and salinity were assessed. Estimated deliveries to consumptive uses in the Upper Basin states of Colorado, Utah, Wyoming, New Mexico, and northern Arizona were heavily affected by the severe drought, while the Lower Basin states of California, Nevada, and Arizona suffered only slight shortages. Upper Basin reservoirs and streamflows were also more heavily affected than those in the Lower Basin by the severe drought. System-wide, total hydropower generation was 84 percent less in the drought scenario than in the historical stream-flow scenario. Annual, flow-weighted salinity below Lake Mead exceeded 1200 ppm for six years during the deepest portion of the severe drought. The salinity levels in the historical hydrology scenario never exceeded 1100 ppm.     

A Fast Method for Monitoring Foliage Density in Single Lower-canopy Trees

A subjective visual assessment of foliage density is the mostwidely used rapid method of determining forest health. Forthese assessments to be ecologically meaningful they must bereliable (have low inter- and intra-observer variability) andreadily relate to a measure of physiological or physicalstress. A simple rapid method for assessing percent foliagedensity in lower stature trees is described. This method haslow inter-observer variability (standard deviation betweenobservers=8.6%) and therefore, minimizes the risk ofconfounding the effects of different observers with genuinechanges in density. The percentage changes in this measure offoliage density correlate well with percentage changes inbiomass, allowing a ready interpretation of observed changes.The technique does not specifically identify the cause of themeasured changes, however, with appropriate additionalmeasures this problem may be overcome.     

Jointly estimating survival and mortality: integrating recapture and recovery data from complex multiple predator systems

Environmental and Ecological Statistics - Identifying where, when, and how many animals live and die over time is principal to understanding factors that influence population dynamics....     

A second case of intrauterine growth retardation and primary hypospadias associated with a trisomy 22 placenta but with biparental inheritance of chromosome 22 in the fetus

We report a case of severe intrauterine growth retardation (IUGR) and hypospadias in association with trisomy 22 diagnosed following chorionic villus sampling (CVS). Subsequent analysis of amniotic fluid cultures showed a normal male karyotype, 46,XY. As a previous case had been reported with similar abnormalities, in association with maternal uniparental disomy (UPD) 22, molecular studies were also performed. Microsatellite marker studies showed biparental inheritance. Follow-up studies after delivery showed a normal cell line in lymphocytes with the trisomy appearing to be confined to the placenta. The present case concurs with other earlier reports that maternal UPD for chromosome 22 has no impact on the phenotype. The features seen in the fetus are most likely the result of placental dysfunction due to trisomy, tissue-specific mosaicism and/or the effects of local growth restriction. Copyright © 2002 John Wiley & Sons, Ltd.