The field of urban ecology has progressed since the mid-1990s through four major phases: an ecology in, of, for, and with cities. This progression reflects an interest to address the complexity of urban systems with social-ecological approaches. Further, this progression signifies an interest to address societal issues by co-designing and co-producing research in collaboration with diverse stakeholders from government, non-governmental organizations (NGOs), businesses, and community associations. What remains unaddressed in this progression is a research mission orientation. While there may be a range of goals for an ecology with cities, a focus on regenerative urban ecologies is crucial. Regenerative ecologies may be seen as an endpoint along a continuum from degenerative ecologies to sustainability to regenerative ecologies. Regenerative ecologies rely upon feedback loops, similar to coral reefs and climax forests. In urban systems, these feedbacks in social-ecological systems may be considered virtuous cycles that create reinforcing, positive benefits for people and nature over time. Virtuous cycles or feedbacks are often conceived as a singular, positive feedback loop. However, virtuous cycles may be most impactful, adaptive, and resilient when they contain multiple positive and negative feedbacks and synergies. Research has several important roles in advancing virtuous cycles and regenerative urban ecologies. In this paper, we use our urban wood systems project in Baltimore as both a case study and model to illustrate an approach and lessons learned for regenerative ecologies, virtuous cycles, and the role of research. We conclude with lessons learned and consider opportunities and constraints for virtuous cycles, research, and regenerative urban ecologies in Baltimore and to other urban systems.

Abstract To promote urban sustainability and resilience, there is an increasing demand for actionable science that links science and decision making based on social–ecological knowledge. Approaches, frameworks, and practices for such actionable science are needed and have only begun to emerge. We propose that approaches based on the co‐design and co‐production of knowledge can play an essential role to meet this demand. Although the antecedents for approaches to the co‐design and co‐production of knowledge are decades old, the integration of science and practice to advance urban sustainability and resilience that we present is different in several ways. These differences include the disciplines needed, diversity and number of actors involved, and the technological infrastructures that facilitate local‐to‐global connections. In this article, we discuss how the new requirements and possibilities for co‐design, co‐production, and practical use of social–ecological research can be used as an ecology for the city to promote urban sustainability and resilience. While new technologies are part of the solution, traditional approaches also remain important. Using our urban experiences with long‐term, place‐based research from several U.S. Long‐Term Ecological Research sites and U.S. Department of Agriculture, Forest Service Urban Field Stations, we describe a dynamic framework for linking research with decisions. We posit that this framework, coupled with a user‐defined, theory‐based approach to science, is instrumental to advance both practice and science. Ultimately, cities are ideal places for integrating basic science and decision making, facilitating flows of information through networks, and developing sustainable and resilient solutions and futures.

Obstacles to Tree-Planting Programs in East BaltimoreIn 2006, government officials in Baltimore announced plans to double the city's tree canopy over the next thirty years.While the effort has already produced positive results, many parts of the city still lack trees.In this paper we consider whether two neighborhoods in East Baltimore -Berea and Madison-Eastend -are suitable locations for tree planting.We begin by calculating how much plantable space exists in each neighborhood.We then use interview data to cast light on how residents value the urban forest and whether or not they would support efforts to increase tree canopy in East Baltimore.The selection of East Baltimore as a study area is significant because it was here that the city's Division of Forestry encountered resistance to tree planting in the 1960s.A secondary goal of our research is to determine whether a shift in the ethnic profile of this section of the city over the past fifty years has changed the way residents perceive and value the urban forest.Our results show that while there is enough plantable space in these two neighborhoods to increase tree canopy, from approximately six percent to over 16 percent, residents are not yet ready to fully embrace an aggressive tree planting program.

Urban Tree Canopy (UTC) Prioritizations can be both a set of geographic analysis tools and a planning process for collaborative decision-making. In this paper, we describe how UTC Prioritizations can be used as a planning process to provide decision support to multiple government agencies, civic groups and private businesses to aid in reaching a canopy target. Linkages to broader City-scale sustainability plans are explored. This article represents an extension and update to the UTC Canopy Goal Setting Guide by Raciti et al (2006). We conclude with recommendations for a market-like analysis of neighborhoods to better match planting initiatives to particular neighborhoods’ motivations, capacities and interests in order to improve the adoption of improved urban forestry practices.

The Water and Watersheds program has made significant and lasting contributions to the basic understanding of the complex ecological system of Baltimore, MD. Funded at roughly the same time as the urban Long- Term Ecological Research (LTER) project in Baltimore, the Water and Watersheds grant and the LTER grant together established the Baltimore Ecosystem Study (BES) in 1997. This joint project took advantage of three conspicuous stream catchments and the direct harbor drainage in metropolitan Baltimore. Not only the watersheds themselves, but the community and political interest in those watersheds were crucial to the success and application of our project.

In 2005, Maryland’s tree expert licensing law, initially enacted in 1945, was amended to include tree removal as an activity requiring a tree expert license. The Maryland Department of Natural Resources (MD DNR) sought to identify and communicate with the potentially affected community regarding the pending changes in the law by a number of means, including a search of companies advertising tree services in Maryland by online phone listings. The majority of firms (69.91%) found to be advertising tree services online were unlicensed tree experts (UnLTEs). A significant number of those UnLTEs (40%) did not provide full contact information, including a street address, and no current address was available for over 25% of them. Only 21 of the UnLTEs studied had ever been the subject of a complaint to MD DNR and those firms accounted for only 18.2% of complaints MD DNR received regarding UnLTEs during a 10 year period. UnLTEs were found in approximately equal measure in one of three business types: incorporated, unincorporated, or unknown (sole proprietorships, general partnerships, or noncompliant). UnLTEs are fairly ubiquitous in small numbers across Maryland with the largest concentrations found close to the borders of adjacent states, in the northeast metropolitan area of Maryland’s largest city (Baltimore), and around the state capital (Annapolis).

The Tree City USA (TCUSA) program is a national program in the United States that provides recognition to communities that meet certain standards, including having a tree ordinance and spending at least US$2.00 per capita on urban forestry. Census data for 2000 were combined with records on TCUSA program participation and tree canopy cover data for 74 communities in Maryland, U.S., to ascertain relationships among tree canopy quantity, community demographics, and Tree City USA program participation. Communities participating in TCUSA had widely varying demographics (2.2% to more than 97% nonwhite) but tended to have larger overall populations and larger nonwhite populations than did nonparticipating communities, with the percentage of nonwhite population slightly higher for nonparticipants. Multivariate statistical analysis showed that the most predictive variable related to the amount of canopy cover is the size of the city in hectares (acres). A combination of city population, hectares (acres) of tree cover, expenditures per capita on trees, and city size in hectares (acres) produced the greatest predictability in whether a city participates in the TCUSA program. The relationship between quantity of tree canopy and total population was stronger in participating than in nonparticipating communities. However, the relationship between land area and quantity of tree canopy was stronger for nonparticipants than for participants, and overall percentage of canopy cover as well as mean percentage of canopy cover were higher in nonparticipating communities. TCUSA participants in Maryland have similar land areas, similar ethnic demographics, higher populations, and canopy coverage more closely related to population than land area when compared to non-TCUSA communities and are most likely to be found in an urban/suburban context, while non-TCUSAs are more likely to be found in a rural (agricultural/forest) context.

The Maryland Roadside Tree Law places trees in all public road rights-of-way in the State of Maryland, U.S., under the jurisdiction of the Maryland Department of Natural Resources-Forest Service. Passed in 1914, this law is one of the oldest tree conservation laws in the United States. However, little statistical data have ever been generated related to Maryland's roadside trees. This paper provides a methodology for assessing the condition of roadside trees by combining GIS tools, rights-of-way definitions, and components of a national forest health monitoring program. The assessment of roadside trees was carried out in six of Maryland's most urbanized jurisdictions. Results indicate that 14% of Maryland's roadsides are tree lined and that the trees are in good health based on crown and damage indicators collected. Shannon-Weaver index and importance values were calculated to describe species diversity. Views on the efficacy of the law in protecting roadside trees in light of the findings, and the findings themselves, are discussed.

The Maryland Forest Conservation Act (FCA) was passed in 1991 to protect the state's forest resources during development. Compliance is required for any project for which grading is required on a unit of land 40,000 ft2 (0.42 ha) or greater. Applicants must generate and submit two documents. The first, a forest stand delineation (FSD), must identify forest stands, specimen trees, and sensitive areas such as steep slopes, hydric or erodible soils, critical habitat areas, streams, and floodplains. This map is used to direct the location of the impacts away from priority areas onsite. The second, a forest conservation plan (FCP), follows a priority sequence concerning impacts to and retention of priority areas identified in the FSD. Thresholds for clearing, afforestation, and reforestation are established based on the net tract area, land-use category, existing forest cover, and proposed clearing area. Forest and tree protective measures are required for stand edges and specimen trees. Long-term protective instruments are required to ensure that the retained area will remain forested. In its first five years, FCA has been responsible for the retention of more than 22,000 ac (10,000 ha) of forest, and 120% more forest retained and planted than has been cleared for development.

As a consequence of compacted soils, impervious surfaces, heat irradiation, pollution, and other stresses, urban trees have an average expected service life of 10 to 25 years. Most public agency budgets for street tree replacement and maintenance are declining. Public tree managers need tools to prolong the service life of street tree populations while reducing the need for maintenance activities (including pruning and pest management). Many jurisdictions rely on “approved tree” lists, but these often contain large numbers of species generally unavailable in a given area, and filters for diversity are seldom part of these documents. To avoid catastrophic losses and pest outbreaks associated with virtual monocultures, the Maryland Department of Natural Resources has developed a methodology for assessing biodiversity in existing populations. An inventory is taken. The results of the inventory are broken down taxonomically by family, genus, and species; The results are then analyzed, with target levels established as follows: no more than 30% of any one family, 20% of one genus, or 10% of one species should be present. Based on the results of the assessment, recommendations are made as a tool for use in future replacement contracts to bring about the desired species composition.

In Maryland, persons engaged in the work of the treatment and care of trees for compensation must be licensed by the Department of Natural Resources. The Department of Natural Resources—Forest Service, the Mid- Atlantic Chapter of the International Society of Arboriculture, the Maryland Arborist Association, and the Maryland Community Forest Council cosponsored a survey of Licensed Tree Experts (LTEs). The survey's purposes were to estimate the total number of jobs and gross dollar revenue that the arboricultural industry provides to the state of Maryland; to identify the tree care industry as a constituency in the business community; to identify training resources and trade affiliations most used by LTEs; to identify business type, geographic concentration, and client type; and to provide input into agency regulations affecting the industry. It is estimated that the tree care industry in Maryland employs 2,841 individuals and generates more than $134.5 million in annual gross revenue.

The SUFA: Baltimore City is a partnership between the USDA-Forest Service, Maryland DNR (Forest Service, Chesapeake and Coastal Watershed Service), Baltimore City Department of Planning, the Parks and People Foundation, and other local NGOs. This project took concepts of the Maryland Department of Natural Resources' Strategic Forest Lands Assessment (SFLA) and applied them to an urban scale. The grant provided for a high -resolution tree canopy and land cover analysis of the city. Leaf -on IKONOS satellite imagery was obtained by the MD DNR for the entire city of Baltimore, Maryland for Oc tober 2, 2001. The ERDAS Imagine Resolution Merge application was used to sharpen the 4-meter multi-spectral data. A vegetation mask was created from the NIR-to-Red, (Band4:Band3) ratio image. A texture image of the ratio image was produced to separate tree canopy from vegetation pixels. The resultant vegetation and tree canopy bit-masks were exported to ESRI GRID files from ERDAS Imagine. Initial statistics generated from these GRID files show total vegetation (trees and other vegetation) as 47 perce nt, non-tree vegetation at 27 percent and tree canopy as 20 percent of the Baltimore land area. The Baltimore City Department of Planning will overlay in-house GIS layers of site types to establish baseline canopy cover. The bit masks were used in combin ation with other data reported by the Baltimore Neighborhood Indicators Alliance (BNIA). The SUFA: Baltimore will serve as a long-term green infrastructure and planning template for Baltimore City and partners.