Andrew K. Koeser

Drought and constrained municipal budgets are increasing demand for establishment practices that conserve water and labor. This study quantified trade-offs between inputs (water, labor, cost) and tree outcomes across irrigation methods and root-ball correction practices during establishment of American sycamore (Platanus occidentalis L.). In December 2022, forty-five 45-gal trees were planted in Gainesville, Florida, in a completely randomized design combining three root treatments (control, shaved, sliced) with three irrigation methods (hand watering, hydrogel bag, conventional slow-release bag). Over 23 months, trunk caliper, height, midday stem water potential, and anchorage (bending stress at 1° inclination) were analyzed using linear mixed-effects models; survival, labor, water, and cost inputs were compared descriptively. Labor differed by two orders of magnitude, but total cost ranked nearly opposite. All trees survived; irrigation method affected no measured response: trees receiving no scheduled irrigation after an initial hydrogel charge were indistinguishable from those hand-watered 48 times (differences within 10–12%). Shaving increased the bending stress required to tilt the trunk 81% over controls, indicating firmer anchorage, without altering growth or water status; slicing had no effect. Under the dormant-season, average-rainfall conditions tested, shaving improved anchorage at negligible cost, and irrigation method had no measurable effect on tree performance.

Tree mitigation policies are regulations that require replacement or compensation for the removal of urban trees and are among the most widely used mechanisms in tree governance. These policies vary in structure, rigor, and terminology across jurisdictions. In this study, we review mitigation-based tree protection policies enacted at local and county levels across the entire United States (n=162), focusing on cases where the replacement ratio exceeds one tree removed compensated by one new tree replanted. We analyze specific replacement ratios (how many trees should be planted for each tree removed), size standards for replacement, species requirements, and procedural conditions encoded in policies, local codes, and ordinances. We found that most mitigation provisions use variable, size-based replacement ratios, often calculated using diameter at breast height (DBH) or caliper inches, the number of trees, the size of the tree canopy, or a combination of these mechanisms. Alternatives to tree replacement include fee-in-lieu or tree banks. Our analysis also reveals variation in related policy provisions, including species-specific requirements for protection and replacement, conditions for on-site versus off-site tree installation, replanting timelines, performance bonds, and post-planting monitoring. We relate these findings to the broader literature on urban forest governance and the landscape of incentive-based policies, discussing implications for more holistic, life-cycle-oriented urban tree management.

Urban parks are widely recognized for their mental health benefits, especially among frequent visitors. However, the factors underlying regular park use among older urban residents remain poorly understood. This study examined park features, motivations, and barriers associated with park visitation frequency among Florida residents aged 45 and older. Using an online survey panel, data were collected from 1,237 participants across Florida's urban areas. Respondents were classified as frequent visitors (≥ once per week; 33.0%) or infrequent visitors (< once per week; 67.0%). Logistic regression was used to examine associations between perceived features, barriers, motivations, and visitation frequency. Among all barriers tested, only perceived distance significantly predicted infrequent visitation (OR = 1.99, p = .002), while commonly cited obstacles such as lack of time and weather did not reach significance. Among individual motivations, exercise (OR = 2.31, p < .001) and walking dog (OR = 2.10, p < .001) were significant predictors of frequent visitation. Connection with nature (60.9%), stress relief (56.3%), and exercise (48.3%) were the most commonly reported motivations overall. Frequent visitors were more likely to prioritize active features such as walking and biking paths and open spaces, while infrequent visitors favored quiet environments, safety and visibility, and seating areas. Older age and being male were significant sociodemographic predictors of frequent visitation. Natural vegetation and tree cover did not significantly predict visitation frequency. These findings suggest that park programming and design strategies aimed at building motivational pull, particularly by supporting structured physical activity, may be more effective at promoting regular engagement with urban green spaces than focusing primarily on barrier removal.

Tree cover near buildings has become a growing concern for homeowner insurance companies in hurricane-prone areas due to the potential for storm damage. Policies requiring the removal of trees located near or overhanging homes as a precondition for new coverage are not new to Florida, but they have become increasingly common as a risk-mitigation strategy. In this study, visual canopy analysis was used to interpret 3,500 random points across Florida, United States, in order to assess the potential statewide impacts of these tree-removal policies. Results indicate that insurance-related pruning and removal mandates could reduce Florida’s overall canopy coverage in developed areas by 588.5 square kilometers. Using ecosystem service models, this reduction was estimated to result in the loss of approximately 6,074 tonnes of air-pollutant removal capacity, more than 11.1 billion liters of avoided stormwater runoff, and 294,250 tonnes of carbon sequestration annually. These findings may help guide public policy and insurance industry practices by highlighting the broader ecological and economic consequences of large-scale tree removal in developed areas.

Background: When branches lack a defined collar, arborists are left without a clear target to guide removal pruning. A common recommendation is to cut at a 45° angle from the branch bark ridge. Cutting perpendicular to the branch axis as an alternative would minimize effective wound size, potentially reducing wood dysfunction in the remaining stem. Methods: A total of 92 Acer rubrum L. ‘Florida Flame’ and 102 Quercus virginiana Mill. ‘Highrise’ branches without visible collars were pruned one of two ways: 1.) removal cut angle 45° from the branch bark ridge (45°) or 2.) removal cut angle perpendicular to the branch axis (perpendicular). Three years later, pruned areas were harvested and assessed for wound closure and internal discoloration and decay, controlling for initial branch diameter, branch-to-parent-stem aspect ratio, sprout growth, and branch height. Results: In live oak, branch size and cut method affected the amount and length of discoloration observed. In red maple, discoloration and decay were largely a function of branch size and aspect ratio (i.e., the relative size difference between the removed branch and parent stem). In both species, cambial dieback was more common with perpendicular removal cuts, often negating any initial benefit associated with the smaller wound. Conclusions: When removing branches without a branch collar, we recommend making 45° cuts. Identifying which branches to remove or retain early in a tree’s life is important to avoid large branch removal cuts later.

Nursery producers and tree giveaway hosts must do their best to anticipate demand for the wide range of species and traits available. When trying to gauge customer response to various product design choices, companies often employ conjoint analysis to determine what features garner the most customer interest. For this study, we used the method to assess various tree attributes ranging from mature size to hurricane resistance. Our findings indicate that large nursery trees significantly deter consumer interest, though it remains unclear whether this is due to their cost or physical bulk. Similarly, consumers preferred trees that grew to small- and medium-stature at maturity over large-stature trees. Trees labeled as Florida-Friendly, native, or hurricane-resistant had a strong positive effect on purchasing interest among Florida residents.

Trees located on private property constitute a substantial portion of the urban forest canopy, yet management responsibilities vary widely across different jurisdictions. While property owners are granted freedom over their land-use decisions, some governments promote tree preservation by regulating and restricting how property owners manage trees on their properties. Incentive-based policies for tree protection can serve as an alternative to enact behavior change through positive reinforcement. In this study, we provide a comprehensive national review in the United States (U.S.) to identify, consolidate, and organize existing urban forest incentives offered by local governments targeting private property owners. In reviewing codes and official government websites across all U.S. states and the District of Columbia, focusing on communities with populations of over 50,000 (n=1839), we found that 27.90% of these locations included provisions for offering some type of incentive to property owners, and 6.14% indicated plans to add such practices in future updates. We organized these mechanisms into 15 broad categories to improve navigation and highlighted some examples to present a wide range of possible approaches for adopting and implementing these practices. Our results indicate that incentives are not always substantiated in official documents, can vary in ease of implementation, and often target only one stage of a tree’s life cycle. We align with previous research that there is no “one-size-fits-all” approach and conclude that it is important to consider the holistic process of a tree’s life cycle, the specific and individual details for each situation, as well as evaluate long-term impacts before tailoring the most suitable incentive mechanism for context-appropriate urban forest management plans.

Background: Tree roots colonize cracks in rock and similarly confining spaces in built environments, contributing to natural weathering processes and urban infrastructure dysfunction. Methods: In this study, we assessed the limits of radial expansion in woody Quercus virginiana Mill. and Taxodium distichum (L.) Rich. roots grown in clamps under increasing tension. Results: After two growing seasons, a maximum stress threshold for radial growth in mature structural roots was identified and was similar for both species. These thresholds (0.173 MPa to 0.329 MPa) fall within the lower to middle range of values reported in previous studies and are notably lower than those observed in seedling radicles or in other woody species under more acute stress exposure. Conclusions: Our findings provide some of the first empirical estimates of pressure thresholds for deformation in mature woody roots, suggesting that structural root flattening can occur at relatively modest stress levels. These results offer important insights for the design of urban infrastructure aimed at minimizing root-related damage while also informing future biomechanical studies of species-specific responses to soil confinement.

Trees in urban environments provide essential ecosystem services, but root growth–pavement system conflicts often constrain tree longevity and degrade infrastructure performance. The study presents a conceptual model for green and grey infrastructure alignment to ensure tree longevity while maintaining pavement performance in the urban environment. Drawing on past research where roots were flattened when exposed to confining stresses greater than 0.35 MPa, we developed a series of finite element models in COMSOL Multiphysics to simulate root-induced stresses in concrete pavements under varying pavement thickness, base thickness, and root depth. Parametric analyses showed that an increase in root depth had the largest impact in reducing stress, followed by an increase in pavement thickness, then base thickness. Maximum single-root-induced stresses were approximately 0.55 MPa, below that of normal concrete flexural strength. From these results, design guidance is proposed for tree root accommodation and pavement in existing and new infrastructure, with emphasis on root growth enhancement, pavement durability, and cost-effectiveness measures.