A Multiview Semantic Vegetation Index for Robust Estimation of Urban Vegetation Cover

Urban vegetation growth is vital for developing sustainable and liveable cities in the contemporary era since it directly helps people’s health and well-being. Estimating vegetation cover and biomass is commonly done by calculating various vegetation indices for automated urban vegetation management and monitoring. However, most of these indices fail to capture robust estimation of vegetation cover due to their inherent focus on colour attributes with limited viewpoint and ignore seasonal changes. To solve this limitation, this article proposed a novel vegetation index called the Multiview Semantic Vegetation Index (MSVI), which is robust to color, viewpoint, and seasonal variations. Moreover, it can be applied directly to RGB images. This Multiview Semantic Vegetation Index (MSVI) is based on deep semantic segmentation and multiview field coverage and can be integrated into any vegetation management platform. This index has been tested on Google Street View (GSV) imagery of Wyndham City Council, Melbourne, Australia. The experiments and training achieved an overall pixel accuracy of 89.4% and 92.4% for FCN and U-Net, respectively. Thus, the MSVI can be a helpful instrument for analysing urban forestry and vegetation biomass since it provides an accurate and reliable objective method for assessing the plant cover at street level.

Lessons Learned from Developing Best Management Practices for Urban Tree Care and Wildlife

Urban forests create indispensable habitat for declining wildlife populations. The tree care industry is essential to the viability of urban forests and thus the survival of urban wildlife. At the same time, tree care operations such as tree removal and branch pruning present clear threats to urban wildlife and their habitats. Here we describe the development of a grassroots coalition of arborists and wildlife advocates in the Western United States and the process of charting a path to best management practices and professional training to mitigate the impacts of tree care practices to wildlife. In particular, we describe the unique challenges and opportunities that arose through this multi-disciplinary process and build a case for the benefits of uniting diverse communities of practice around complex urban ecological problems. We finish by laying out recommendations to the international arboriculture and urban forestry practitioner and research communities.

Invasive Plant Relations in a Global Pandemic: Caring for a “Problematic Pesto”

In Spring 2020, amidst a COVID-19 state of emergency, the City of Toronto's Parks & Urban Forestry department posted signs in the city's remaining Black Oak Savannahs to announce the cancellation of the yearly ‘prescribed burn’ practice, citing fears it would exacerbate pandemic conditions. With this activity and other nature management events on hold, many invasive plants continued to establish and proliferate. This paper confronts dominant attitudes in invasion ecology with Indigenous epistemologies and ideas of transformative justice, asking what can be learned from building a relationship with a much-maligned invasive plant like garlic mustard. Written in isolation as the plant began to flower in the Black Oak savannahs and beyond, this paper situates the plant's abundance and gifts within pandemic-related ‘cancelled care’ and ‘cultivation activism’ as a means of exploring human-nature relations in the settler-colonial city. It also asks what transformative lessons garlic mustard can offer about precarity, non-linear temporalities, contamination, multispecies entanglements, and the impacts of colonial property regimes on possible relations. Highlighting the entanglements of historical and ongoing violences with invasion ecology, this paper presents ‘caring for invasives’ as a path toward more liveable futures.

Structural Stability of Urban Trees Using Visual and Instrumental Techniques: A Review

This review focuses on tree health assessment in urban forest, specifically on the methodologies commonly used to detect levels, dimensions, and location of wood deterioration. The acknowledged benefits to the urban forestry area from the application of assessment techniques are also addressed. A summary is presented of the different methodologies, such as visual analyses, acoustic tomography, and digital wood inspection drill, with the underlined importance of the biodeterioration of wood by fungi and termites.

Remotely Sensed Tree Characterization in Urban Areas: A Review

Urban trees and forests provide multiple ecosystem services (ES), including temperature regulation, carbon sequestration, and biodiversity. Interest in ES has increased amongst policymakers, scientists, and citizens given the extent and growth of urbanized areas globally. However, the methods and techniques used to properly assess biodiversity and ES provided by vegetation in urban environments, at large scales, are insufficient. Individual tree identification and characterization are some of the most critical issues used to evaluate urban biodiversity and ES, given the complex spatial distribution of vegetation in urban areas and the scarcity or complete lack of systematized urban tree inventories at large scales, e.g., at the regional or national levels. This often limits our knowledge on their contributions toward shaping biodiversity and ES in urban areas worldwide. This paper provides an analysis of the state-of-the-art studies and was carried out based on a systematic review of 48 scientific papers published during the last five years (2016–2020), related to urban tree and greenery characterization, remote sensing techniques for tree identification, processing methods, and data analysis to classify and segment trees. In particular, we focused on urban tree and forest characterization using remotely sensed data and identified frontiers in scientific knowledge that may be expanded with new developments in the near future. We found advantages and limitations associated with both data sources and processing methods, from which we drew recommendations for further development of tree inventory and characterization in urban forestry science. Finally, a critical discussion on the current state of the methods, as well as on the challenges and directions for future research, is presented.

Twenty Years of Providing Free Plants in An Urban New Zealand Setting: What Affects Community Participation and Planting Success?

<p>An urban greening programme in Wellington, New Zealand providing free plants to city residents was evaluated with the following objectives: 1. To assess the levels of plant survival after five, ten, and fifteen years and determine factors contributing to observed survival; 2. To investigate factors influencing participation in the programme; 3. To quantify the some of the socioeconomic factors relating to programme participants and environmental factors relating to sites. Data were collected from a combination of council records, site surveys and postal questionnaire surveys. The study found that plant survival was generally poor, but was mainly influenced by indigeneity of the plants. Contrary to many theories of exotic invasiveness, New Zealand native plants were 4.3 times more likely to survive than exotic plants. Site based effects were not found to influence survival significantly; nor were specific plant traits, or year of planting. A small sample of these sites was matched to questionnaire responses and it was found that length of residence by programme participants increased the performance of the best model indigeneity, indicating that increasing length of residence was a predictor of better survival of plantings. The questionnaire respondents included both those who had participated in the programme and those who had not. The sample population, however, was quite distinct from the general population of the region, being older, wealthier, having higher levels of education, and twice as likely to own their own home. As suggested by previous research looking at the effects of socioeconomic factors on urban forestry or urban greening participation was shown in this study to be mainly affected by the age of the respondent, which increased the odds of participation by 200% between the youngest and oldest age groups. This socioeconomic model was improved when two factors were included: the number of trees outside their property, and, horticultural knowledge of the participant. This indicates that participants might be more motivated by personal interest in horticulture, than in improving environmental conditions.</p>

Twenty Years of Providing Free Plants in An Urban New Zealand Setting: What Affects Community Participation and Planting Success?

<p>An urban greening programme in Wellington, New Zealand providing free plants to city residents was evaluated with the following objectives: 1. To assess the levels of plant survival after five, ten, and fifteen years and determine factors contributing to observed survival; 2. To investigate factors influencing participation in the programme; 3. To quantify the some of the socioeconomic factors relating to programme participants and environmental factors relating to sites. Data were collected from a combination of council records, site surveys and postal questionnaire surveys. The study found that plant survival was generally poor, but was mainly influenced by indigeneity of the plants. Contrary to many theories of exotic invasiveness, New Zealand native plants were 4.3 times more likely to survive than exotic plants. Site based effects were not found to influence survival significantly; nor were specific plant traits, or year of planting. A small sample of these sites was matched to questionnaire responses and it was found that length of residence by programme participants increased the performance of the best model indigeneity, indicating that increasing length of residence was a predictor of better survival of plantings. The questionnaire respondents included both those who had participated in the programme and those who had not. The sample population, however, was quite distinct from the general population of the region, being older, wealthier, having higher levels of education, and twice as likely to own their own home. As suggested by previous research looking at the effects of socioeconomic factors on urban forestry or urban greening participation was shown in this study to be mainly affected by the age of the respondent, which increased the odds of participation by 200% between the youngest and oldest age groups. This socioeconomic model was improved when two factors were included: the number of trees outside their property, and, horticultural knowledge of the participant. This indicates that participants might be more motivated by personal interest in horticulture, than in improving environmental conditions.</p>