Treesearch

Urban forests impact energy use for cooling and heating as a result of their moderating influence on climate. To evaluate the regional magnitude of these impacts, a large-scale analysis framework was developed and applied to Sacramento County, California, as a case study. Heating, cooling, and peak electrical energy use changes resulting from modification of solar radiation, air temperature, and wind speed by the existing urban forest were estimated for representative residential and commercial buildings. This is combined with building age and size, canopy and tree cover, and tree density...

We compared the accuracy of five methods used to estimate leaf area index (LAI) of eight open-grown deciduous trees, including six white mulberries (Moms alba) and two black cherries (Prunus serotina var. rufula). The methods included the use of four instruments (AccuPAR Ceptometer, CI-100 Plant Canopy Analyzer, image processing with the AgVision System, LI-COR LAI-2000 Plant Canopy Analyzer) and the application of a logarithmic regression equation. The image processing method demonstrated the highest probability of accurately estimating LAI (P = 0.99). However, all methods showed bias...

Concern about global climate change and the effects that increasing atmospheric carbon dioxide could have on the earth has risen in recent years. Methods for accurately and efficiently quantifying carbon storage and annual carbon fluxes are needed to determine what role urban forests may have in reducing levels of atmospheric CO2. This will require the development of techniques for estimating foliar and woody biomass of individual trees. In this study, 2 sampling methods and 2 regression formulas for estimating foliar and above-ground woody biomass were tested against the actual above-groun...

The urban forest of Sacramento County, California, contains approximately 6 million trees. Tree density and basal area decrease along an urban-rural gradient from city (73 trees/ha, 13.4 m2 /ha), to suburban (64 trees/ha, 4.5 m2 /ha), to rural (10 trees/ha, 0.9 m2 /ha) sectors. Within the city and suburban sectors, where 90% of all residents live, approximately 75% of total tree numbers, basal area, and leaf area occurs on residential land. Sacramento's urban forest is relatively sustainable. Seventy percent of the trees are in excellent or good condition, the population is well distributed...

A one-dimensional mass and energy balance model was developed to simulate rainfall interception in Sacramento County, California. The model describes tree interception processes: gross precipitation, leaf drip, stem flow, and evaporation. Kriging was used to extend existing meteorological point data over the region. Regional land use/ land cover and tree canopy cover were parameterized with data obtained by remote sensing and ground sampling. Annual interception was 1.1% for the entire county and 11.1% of precipitation falling on the urban forest canopy. Summer interception at the urban...

A dry deposition model was employed to estimate air pollutant uptake by Sacramento's urban forest. Assuming 1990 air pollutant concentrations, model simulations estimated that approximately 1,457 metric tons of air pollutant are absorbed annually, at an implied value of US$28.7 million. The growing season daily uptake for ozone was approximately 2.4 metric tons per day, while particulate matter (< 10 μ diameter, PM10) uptake was slightly greater, at 2.7 metric tons per day. Daily uptake of NCX, and particulate matter represented 1 % to 2% of anthropogenic emissions for the county. Estimated...

Sacramento County's 6 million trees store 8 million tons of CO2 (31 t/ha), and annually sequester 238,000 t (0.92 t/ha). Air-conditioning (157 GWh) and space-heating (145 TJ) savings from the urban forest further reduce emissions by 75,600 t of CO2 annually (0.29 t/ha). These avoided emissions are only 32% of the amount sequestered, due to a clean, hydroelectric energy supply. Annual CO, release associated with tree maintenance is estimated at 9,400 t (0.04 t/ha), or 3% of the amount sequestered and avoided. In net, the urban forest removes approximately 304,000 t (1.2 t/ha) each year,...

The ecological view in urban forestry evolved from diverse roots beginning over 100 years ago and is currently expressed in formal programs of research and practice. Among the most useful concepts in urban forest ecology are structure, function, diversity, dominance, mosaic-gradients, and ecosystems. These concepts assist in understanding changes in ecological states that produce changes in the distribution of benefits and costs. The ecological history of urban forestry provides these concepts as points of departure for two special issues of the Journal of Arboriculture devoted to the...

Over the course of 150 years, a combination of cultural and natural processes drove Sacramento's transition from City of the Plains to the City of Trees. This paper describes how the many authors of Sacramento's treescape have affected the health, management, and public perception of the city's trees. Local government directed early street and park tree plantings and banned problem tree species by ordinance. During the first half of the 20th century, participation in street tree planting and preservation by groups such as the Chamber of Commerce, Boy Scouts, Science Teachers Association,...

Site surveys were conducted on residential properties in Sacramento, California, and residents were given questionnaires about whether they had added trees to their properties, their motivations for planting trees, and the extent and frequency of their maintenance of the trees on their properties. These surveys indicate that most residents (68% of the sample) plant trees on their properties; that residential areas are relatively densely planted (with room for about 9% more trees than are already in place); that issues of comfort (shade) and appearance play more of a role in the decision to...