Estimating the alignment of tree species composition with foraging practice in Philadelphia's urban forest: Toward a rapid assessment of provisioning services

Urban greenspaces (UGS) are increasingly recognized for their potential to provide provisioning services to residents foraging for food and other plant materials. The alignment of tree species composition with foraging practices in cities, and the provisioning services harvesters derive, in UGS remains less well studied. To address this gap, we draw on existing tree species data and forager practices in the City of Philadelphia to estimate the alignment between tree species composition and foraging in the city. Our approach uses an existing forest inventory, an international online database of useful species, online information for residents about useful species found in the city, and novel data about forager practices. By considering these datasets in tandem, we are able to identify useful tree species, species likely of interest to foragers, and species actively foraged, and estimate the relative abundance of species in each category. Our results suggest that managers may be able to analyze proxy data, through use of online quality ratings, to rapidly identify and assess forager interest in species found in their urban forests.     

Exotic trees contribute to urban forest diversity and ecosystem services in inner-city Cleveland,OH

Vacant land, a product of population and economic decline resulting in abandonment of infrastructure, has increased substantially in shrinking cities around the world. In Cleveland, Ohio, vacant lots are minimally managed, concentrated within low-income neighborhoods, and support a large proportion of the city’s urban forest. We quantified abundance, richness, diversity, and size class of native and exotic tree species on inner-city vacant lots, inner-city residential lots, and suburban residential lots, and used i-Tree Eco to model the quantity and economic value of regulating ecosystem services provided by their respective forest assemblages. Inner-city vacant lots supported three times as many trees, more exotic than native trees, and greater tree diversity than inner-city and suburban residential lots, with the plurality of trees being naturally-regenerated saplings. The urban forest on inner-city vacant lots also had two times as much leaf area and leaf biomass, and more tree canopy cover. The quantity and monetary value of ecosystem services provided by the urban forest was greatest on inner-city vacant lots, with exotic species contributing most of that value, while native taxa provided more monetary value on residential lots. The predominately naturally-regenerated, minimally managed exotic species on vacant land provide valuable ecosystem services to inner-city neighborhoods of Cleveland, OH.     

The assessment of degradation to sustainability in an urban forest ecosystem by GIS

Different factors affect the sustainability of urban forests. In this study, in order to distinguish the parameters affecting an ecosystem, the man-made Sorkhehesar Park of Iran was divided into homogeneous units (HUs) in accordance with natural (slope, aspect, elevation, soil depth, pure and mixed planting systems) and human (irrigation and recreation levels) factors using GIS, and their effects on ecosystem sustainability were investigated. All tree and shrub species (Fraxinus excelsior, Cercis siliquastrum, Platanus orientalis, Robinia pseudoacacia, Cupressus arizonica, Pinus eldarica, and Cupressus sempervirens) individuals of the park were studied qualitatively and quantitatively. Homogeneous units were identified on the basis of tree height, basal area, crown diameter and symmetry, tree vitality, canopy cover, and density of herbal vegetation. Results showed that the sustainability of the ecosystem was affected by different factors and the limiting factors were pure and mixed plantation system, slope, and soil depth. Local recreation resulted in unsustainability of the site in areas with slopes more than 15% and shallow soil. It was concluded that the status of C. siliquastrum and C. sempervirens individuals was more stable in similar conditions compared to other species.     

Socio-ecological restoration of cultural forests: The case of the Gyeongju historic areas in South Korea

This study seeks to provide a more holistic understanding of traditional forest management. Focusing on cultural/historical sites, this paper highlights the values attributed to historical and cultural landscapes. To restore traditional landscapes and their values, we identified all of the tree species that are currently present in the Oreung royal tomb grove and Gyerim sacred grove in the city of Gyeongju, located in the southeastern area of the Korean peninsula, and compared this to the historical list of species found in these areas by consulting historical documents and old illustrations. The results revealed that a large number of species not part of the original design are present in both the Oreung royal tomb grove (12.51 %) and the Gyerim sacred grove (33.14 %) of the total trees, respectively. Our findings highlight the importance of conserving culturally important species following traditional management strategies to restore historical/cultural landscapes of the past rather than simply increasing biological diversity. This study offers a more comprehensive understanding of the management of traditional forests by incorporating historical and ecological perspectives and suggests future strategies for the conservation of traditional forests.     

Mapping the urban forest in detail: From LiDAR point clouds to 3D tree models

Trees are an integral component of the urban environment and important for human well-being, adaption measures to climate change and sustainable urban transformation. Understanding the small-scale impacts of urban trees and strategically managing the ecosystem services they provide requires high-resolution information on urban forest structure, which is still scarce. In contrast, there is an abundance of data portraying urban areas and an associated trend towards smart cities and digital twins as analysis platforms. A GIS workflow is presented in this paper that may close this data gap by classifying the urban forest from LiDAR point clouds, detecting and reconstructing individual crowns, and enabling a tree representation within semantic 3D city models. The workflow is designed to provide robust results for point clouds with a density of at least 4 pts/m² that are widely available. Evaluation was conducted by mapping the urban forest of Dresden (Germany) using a point cloud with 4 pts/m². An object-based data fusion approach is implemented for the classification of the urban forest. A classification accuracy of 95 % for different urban settings is achieved by combining LiDAR with multispectral imagery and a 3D building model. Individual trees are detected by local maxima filtering and crowns are segmented using marker-controlled watershed segmentation. Evaluation highlights the influences of both urban and forest structure on individual tree detection. Substantial differences in detection accuracies are evident between trees along streets (72 %) and structurally more complex tree stands in green areas (31 %), as well as dependencies on tree height and crown diameter. Furthermore, an approach for parameterized reconstruction of tree crowns is presented, which enables efficient and realistic city-wide modeling. The suitability of LiDAR to measure individual tree metrics is illustrated as well as a framework for modeling individual tree crowns via geometric primitives.