Abstract

Urban land area in North America is expected to double by 2030; currently, 78 percent of the population lives in urban areas, and that proportion is expected to climb (Seto et al. 2012). As the US population grows, urbanization increases the amount of wood waste produced from disposal of unwanted wood items, such as construction and demolition projects, or trimmed and harvested trees in urban and transition areas located between urban and traditional forests (i.e., forest interface areas). The abundant supply of urban wood waste is typically sent to a landfill or used in low-value products, such as mulch or firewood (Nowak et al. 2001; Bratkovich et al. 2007, 2008; Nzokou 2009; Little et al. 2011; Brashaw et al. 2012; Roush and Royer n.d.). Infestation of urban trees by invasive insect species (e.g., emerald ash borer) has caused a tremendous increase in the amount of available roundwood in urban areas due to removal of dead or dying trees. Owing to the increase in wood waste from urban trees, federal, state, and local governments have started to develop new strategies to reclaim wood from this waste (Bratkovich 2002, Brashaw et al. 2012). The increasing concern for climate change issues has caused some to look at using urban wood from trees in value-added wood products applications (e.g., cabinets, furniture, and lumber) instead of allowing the release of carbon from using wood as a fuel source (Bratkovich and Sherrill 2011).

Damaged or worn-out wood products in urban areas have added to the ever-growing amount of wood waste ending up in landfills. Annually, about 70 million tons of wood waste are generated in the United States (Howe et al. 2013). This type of urban wood is classified under the US Environmental Protection Agency (EPA) guidelines for municipal solid waste (MSW) and construction and demolition debris (C&D; Bratkovich et al. 2009, MacFarlane 2009). Wood waste in this category includes cabinets, wood panels, wooden crates, containers, pallets, furniture, scrap lumber, and discarded wood materials (English et al. 2006, Bratkovich et al. 2009). Public demand for sustainability and a need to find better ways to utilize all kinds of wood waste material has raised awareness of urban wood waste; therefore, a clear and practical definition is needed.

Researchers of urban wood waste and other stakeholders often use different definitions when describing wood waste from an urban setting. In the past, these definitions typically evolved from EPA guidelines for MSW (e.g., trash or garbage) from residential, institutional, and industrial sectors. However, within MSW, the EPA separates wood waste into two components: “wood” and “yard trimmings.” The wood component includes C&D (e.g., scrap lumber, cabinets, and wooden furniture), wood containers, pallets, etc. The term “yard trimmings” includes brush, leaves, grass clippings, tree trimmings, and removals (Falk and McKeever 2012, EPA 2013). However, the EPA (2007) definition of urban wood waste includes yard trimmings, wood from C&D projects, site removals, pallets, furniture, packaging, and other commercial or household wood waste that is otherwise disposed of in landfills. It appears that the main regulatory agency for waste has a variable definition for the components included as urban wood waste. Table 1 presents descriptions/definitions of urban wood waste from main stakeholder groups and studies that have used the term.

Table 1. Urban wood waste descriptions by key stakeholder organizations.^a

View Fullscreen

Urbanization creates a variety of wood waste from different sources: waste from living trees and elements of previously manufactured wood products, making the term confusing. The lack of a clear definition may cause stakeholders involved in the utilization and management of urban wood waste to select the meaning of the terms depending on the materials they have at their disposal. Stakeholders need to understand that the types of wood waste included in this material may differ depending the use of the term so that the waste is properly utilized and not just disposed of in a landfill. This leads to the topic of this article: how do various stakeholder groups define urban wood waste? The purpose of this note is to review the current usage of the terminology regarding urban wood waste and to develop a clear definition that can be accepted across stakeholder groups.

Urban Wood Waste as Municipal Solid Waste

The EPA, the leading governmental authority on waste, along with other governmental agencies involved in the utilization of wood, such as the US Forest Service (USFS), have inconsistent definitions of urban wood waste. According to a Forest Products Laboratory USFS publication (Solid Waste Association of North America 2002; Table 1), urban wood waste included sawn lumber, pruned branches, stumps, and whole trees from street and park maintenance. Yet another Forest Products Laboratory study examining the generation and recovery of solid wood in the United States presented the term “urban wood waste” as being similar to the EPA definition as a component of the MSW and C&D waste streams (Falk and McKeever 2012). The studies referenced indicate the difficulty of interpreting the term “urban wood waste” since even scientists within the same agency use the term differently.

State and federal agencies and nonprofit organizations also have variable definitions. The Southeast Michigan Resource Conservation and Development Council identified urban wood waste as part of the EPA guidelines for wood and yard trimmings (Nzokou 2009). The California Integrated Waste Management Board characterized urban waste wood as dimension lumber, brush, trees, etc. that come from municipal sources (Cotton et al. 2001). Other states have similar definitions for urban wood waste (Mangun and Phelps 2005, English et al. 2006, MacFarlane 2009). Public Policy Associates (1994) identified eight components in urban wood waste: pallets, wood scraps, construction waste, demolition debris, railroad ties, tree trimmings, land clearing, and composite wood products. Finally, a 2009 Dovetail Partners report followed the EPA's guidelines for describing waste wood to include municipal solid waste and construction and demolition waste. Their definition described waste wood as similar to the EPA guidelines for C&D; however, they noted additional materials not described in the report that may contribute to urban wood waste, such as trees or woody yard debris (Bratkovich et al. 2009).

Urban Trees as Urban Wood Waste

Wood from urban tree trimmings and removal has been a component of the definition of urban wood waste since the early 1990s (see Table 1). However, the need arose in the early to mid-2000s to find a more value-added utilization method for this material; this need caused some stakeholder organizations to consider only wood from urban trees as the sole source of urban wood waste. Some resources recognize urban wood waste as only that originating from urban trees. Several urban wood utilization studies conducted by the USFS examined harvesting and utilizing urban trees and woody yard residues from municipalities. Their intent was to find ways to increase the value of a historically low-value product, such as mulch or firewood (Bratkovich 2001, Cesa et al. 2003, McKeever and Skog 2003). Several of these studies determined that trees were an important part of the urban wood waste stream (Bratkovich 2001, McKeever and Skog 2003). While these studies looked at ways to utilize trees as a component of urban wood waste, they did not clearly define what constitutes urban wood waste. The Urban Forest Products Alliance (2013), a group of industry, government, and nonprofit organizations with a mission to advance the sustainable recovery and the highest and best use of the products of urban forests, defines urban wood as wood from felled urban trees and trimmings. Similarly, companies (i.e., arborists) that focus on removal and maintenance of urban trees also consider urban trees and woody debris as urban wood waste (Little et al. 2011). The Tree Care Industry Association (2012), the leading trade association for commercial tree care companies, uses the term “urban forest product” to describe a wood product produced from an urban or community tree harvested from residential or public lands. Additionally, some view wood harvested from urban forests as “urban lumber” as opposed to urban wood waste (Allen et al. 2009). In short, to develop better utilization practices, some stakeholders are establishing new terminology that describes the materials they have at their disposal.

Some definitions place more emphasis on residential and community yard waste than construction and demolition waste. In North Carolina, the statues and regulations governing wood waste describe urban wood waste as “yard waste.” Yard waste is broken down into two categories: (1) wood waste from land-clearing debris and (2) yard trash. Land-clearing debris includes trees and other vegetation that is removed during the construction of homes, facilities, and other buildings. Yard trash consists of leaves, tree and shrub branches, logs, wood from landscaping, and storm debris (Heinen et al. 2012). A San Francisco Bay area wood recycling program identified urban tree removals as an important part of the urban wood waste stream (Fairchild 2003). These definitions focused on trees and yard waste as urban wood waste and excluded municipal solid waste items (e.g., wood pallets, furniture, wood containers, packaging) and construction and demolition debris.

As shown in Table 1 and discussed in the previous sections, existing definitions of “urban wood waste” include a variety of items, including urban tree material and discarded wood furniture in an urban setting. While the term “urban wood waste” was once focused more on discarded wood products and has moved to focus more on woody debris, it is clear that the term still commonly includes both in practical use. No separate terms currently exist that focus on one specific source of waste; therefore, a new term or terms would have to be created and adopted across all stakeholder groups. Given the vast use of “urban wood waste” by multiple stakeholders, this would likely lead to significant confusion. The authors suggest that all the stakeholders discussed in this article should use the term “urban wood waste,” but they must clearly define all materials associated with their definition.

Summary

In conclusion, a review of the existing terminology suggests that urban wood waste consists of more than just wood from urban forests or reclaimed from old buildings. However, no standard definition of “urban wood waste” exists among all stakeholder groups. Stakeholders involved in the management and utilization of urban wood waste tend to view the definition within their own context. The main grouping of definitions evolved around the EPA's description of wood and yard trimmings in the MSW category. The wood component includes C&D (e.g., scrap lumber, cabinets, and wooden furniture), wood containers, pallets, and so on. The term “yard trimmings” includes brush, leaves, grass clippings, tree trimmings, and removals. Because the definition of wood waste can vary depending on the user, as demonstrated in this article, it is important for stakeholders to define how they are using the term. Differences in usage of terminology among governing organizations and stakeholder groups may lead to misunderstanding or suboptimal usage of a potential resource. Using the term without a clear definition could also lead to misinterpreting research results, creating unnecessary waste, and limiting potential value-added uses.