UFEI Publications

A Comparison of CA Forest Practice Rules and Two Certification Systems

California’s private forestlands are afforded some of the most extensive legal protection in the world. Multiple layers of federal, state, county and local regulations ensure that timber will be managed in a sustainable manner. In addition to comprehensive state regulations, some forest landowners voluntarily choose to seek third-party certification by the Forest Stewardship Council (FSC) or the Sustainable Foresty Initiative (SFI), entailing a rigorous and expensive evaluation of strict standards by qualified independent auditors who have no vested interest in the forestland in question.

This study investigates how the California Forest Practice Rules (FPRs) and other legal requirements compare to FSC and SFI standards in providing protection to environmental and cultural resources on private forestlands in California. It attempts to not only compare the written standards of each of the three systems, but also attempts to describe how these standards are evaluated in the field.

California Urban Woody Green Waste Utilization

This report deals with one of California’s important “natural” resources, namely, urban trees that are removed for a wide variety of reasons and end-up clogging landfills, or at best are used for firewood or other low value commodities. Historically, productive utilization of this “waste material” for valuable lumber has been minimal; but in recent years, it’s potential use has been recognized by a few resource managers and mill operators. The size of this potential resource, who is currently milling it, its physical characteristics, and how to get into the urban lumber producing business are the subjects of this report.

Community and Urban Forest Inventory and Management Program – Users Guide | CUFIM.zip (MS Excel Programs) 5.9MB

The Community and Urban Forest Inventory and Management program (CUFIM) is one more step in answer to the call for improved management and sustainability of California’s urban forests.

This report presents an Mac Excel-based computer program that can be used to setup and maintain a tree inventory and database, and to evaluate the urban forest in quantative terms including volume and value. It is the hope of the authors that this effort will help urban communities take the next step toward sustainability of the urban forest resource.

Elements of Sustainability in Urban Forestry

For quite some time now people have recognized the value of trees in urban environments. Cities and communities responded to this demand by planting trees wherever and whenever they could afford. Developers were required to participate under simplistic rules like “two trees for every parking space.” The result was the creation of urban forests that were generally not well planned and not sustainable. The purpose of this study was to describe the key elements in a urban forestry program that make it sustainable and to provide direction through examples of cities and communities that are employing some of them.

Just as in wild land settings, a sustainable forest is one which is ecologically sound, socially acceptable, and economically efficient. To achieve this condition, a level of “systems-thinking” is needed. This requires understanding the spatial and temporal interrelationships between programs and management practices.

Long-Term Growth, Sudden Oak Death Assessment and Economic Viability of Coast Live Oak in Three California Counties – 17 Year Results (Volume I)

Long-Term Growth, Sudden Oak Death Assessment and Economic Viability of Coast Live Oak in Three California Counties – 17 Year Results (Volume II)

A long-term thinning study was established in ten stands of coast live oak (Quercus agrifolia Née) in the Central Coast of California in 1984. Information about diameter, basal area, and volume growth and yield has been obtained from unthinned control plots and from plots thinned to 50 and 100 square feet of basal area per acre. Plots were measured in 1984, 1989, 1996, and 2001. Both basal area and total volume growth percentages were significantly greater in the thinned plots compared to control plots. In 2001, Sudden Oak Death study plots were established around the growth plots. Although some trees exhibited suspicious symptoms, all laboratory tests were negative for the pathogen Phytophthora ramorum in the study plots.

Tree Volume Equations for Fifteen Urban Species in California

This study is the first phase of a three-phase urban forest utilization project at Cal Poly, San Luis Obispo. Selected samples of fifteen urban species were carefully measured in order to develop tree volume equations. These species include Chinese Elm, Holly Oak, Camphor Tree, Jacaranda, American Sweet Gum, Monterey Pine, Blue Gum, Monterey Cypress, Acacia (Golden Wattle), Carob, Modesto Ash, Southern Magnolia, Sawleaf Zelkova, London Plane, and Chinese Pistache. Equations for species in three regions (Southland, Coastal and Central Valley) of California were developed. The results of all regions are completed and reported here. Local and standard volume equations were developed for use by urban foresters needing to calculate tree volumes.

Individual tree detection in large-scale urban environments using high-resolution multispectral imagery

A model was developed to predict the value contribution of forest condition on small urban-wildland interface properties. Sample data were collected on property transactions in the Lake Tahoe Basin of California between 1990 and 1994. A variant of the stand density index (SDI) and a tree health measure were added to a list of traditional property characteristics (i.e., location, house size, lot size) to express the influence of tree care on property value. These aesthetic characteristics were statistically significant despite the expected dominant influence of the traditional characteristics. Values for the forest density and health characteristics were estimated and reveal a contribution to property value between 5 and 20 percent.

Street tree diversity and urban heat

Higher diversity within a city’s street trees may offer greater cooling benefits than less diverse urban forests. California’s urban forests are among the most diverse in the world and offer an opportunity to test the relationship between diversity and cooling at a large scale. For 136 urban ZIP codes, we connect the most comprehensive data to date on California’s urban forests to both local station and satellite weather data for the period 2010–2018. We test whether biodiversity, measured by the Shannon-Wiener index and the new Top Diversity 50 index, is correlated with extreme heat in summer. After controlling for local averages in weather and tree canopy cover, we find that urban forest biodiversity is associated with lower maximum and higher minimum temperatures for June to September. Our specification makes it unlikely that reverse causality drives our result. Instead, we suggest that greater tree species diversity may boost daytime cooling through several pathways, including mutualism and greater aboveground biomass, a mechanical relationship where greater biodiversity implies a greater likelihood of having species with excellent shade, and cooling benefits from structural diversity in urban settings.

Diversity and structure in California’s urban forest: What over six million data points tell us about one of the world’s largest urban forests

Urban street trees provide many benefits to surrounding communities, but our ability to assess such benefits relies on the availability of high-quality urban tree data. While these data are numerous, they are not available in an easily accessible, centralized place. To fill this gap, we aggregated public and private data into a single, comprehensive inventory of urban trees in California called the California Urban Forest (CUF) Inventory. These data are offered to the public (aggregated to ZIP code) via an online data portal, which at the time of publication contained over 6.6 million urban tree records. In this study, we first describe the assembly and utility of the inventory. Then, we conduct the most comprehensive assessment of the diversity and structure of California’s urban forest to date at statewide, regional, and local spatial scales. These analyses demonstrate that California’s urban forests are highly diverse and among the most diverse urban forests in the world. We present a new and intuitive metric of species diversity, the top diversity or TD-50 index, which represents the cumulative number of species accounting for the top 50 % abundance of trees in an urban forest. We used species abundance data from 81 well-inventoried cities to demonstrate that the TD-50 index was a robust metric of diversity and a good predictor of comprehensive metrics like the Shannon Index. We also found that small-statured trees, such as crape myrtles (Lagerstroemia cv.) dominate California’s urban forests. This aggregated inventory of one of the world’s largest urban forests provides the data necessary to assess the structure, diversity, and value of California’s urban forests at multiple spatial scales. The inventory’s presentation to the public and the information that can be gained from its analysis can be a model for urban forest management worldwide.

California’s urban forest is composed of both native and non-native species. These trees improve the quality of life of urban residents and mitigate the effects of climate change by buffering local microclimates. A species’ native status is often defined at the scale of the state’s political boundaries, which doesn’t reflect its actual native range. Here we define the list of 95 tree species native to California, create digital range maps for each species, provide native species lists for every city in California, and analyze trends in native tree species in the state’s urban areas. We found that California’s urban areas have relatively few tree species that are native within a given city’s boundaries. Even though non-natives outnumber natives in all California cities, opportunities for more native tree diversity are slim as most cities have less than four native species that aren’t already growing as urban trees. California’s cities face a hotter and drier future, threatening existing urban forests and the benefits they provide residents. We explore different options for tree selection based on the goal of growing healthy and resilient urban forests into the future.

A spatial triage of at-risk conifer forests to support seed collection efforts and sustainable forestry