Urban Forestry & Urban Greening最新文献

Urban agriculture is acknowledged as a multifunctional integrated concept capable of delivering various ecosystem services. Design-related empirical research which is regarded as crucial for introducing and exploring the transformation of design knowledge and practice. Despite the growing body of scientific evidence, operational guidelines for this topic are relatively scarce. The primary step in promoting practical value involves reviewing existing design knowledge and transformation status in empirical research. In conjunction with the existing design research findings, research through design is the only way to acquire and test design knowledge. Spatial design is acknowledged as a way to translate theoretical concepts into practical applications. This systematic literature review offers a comprehensive qualitative analysis of urban agriculture, ecosystem services, and design research. Additionally, it utilizes bibliometric visualization tools to clarify existing research gaps and propose reliable solutions. This paper reveals the imbalance of design research in delivering ecosystem services in urban agriculture through the review of 70 selected empirical research articles. The results suggest that the research for design approach is the most prevalent and offers abundant design knowledge. However, the relatively infrequent use of the research through design method obstructs the transition from implicit to explicit design knowledge, resulting in a shortage of available operational guidelines. Consequently, the study proposes a framework for systematic design knowledge of urban agriculture to catalyze the transformation of design knowledge. Finally, we outline the framework's composition and logic and elucidate its role in addressing research gaps.

Biofiltration systems can fail over time due to clogging by fine sediments in stormwater. Infiltration can be maintained by plant roots, but species selection for biofiltration to date has largely been driven by pollutant removal efficiency and tolerance of conditions. As a result, plant species diversity in biofilters is typically low and dominated by sedges and rushes. Increased use of woody species could in theory improve plant diversity, aesthetic appeal, infiltration under high sediment loads and volumetric runoff reduction via higher evapotranspiration, without jeopardising nutrient pollutant removal. We tested whether shrubs could maintain infiltration and evapotranspiration in biofiltration profiles treated with a high sediment load, by comparing them with biofilters subjected to tap water without sediment. Following sediment application, biofilter columns planted with shrubs with high total biomass and total root length showed higher infiltration and evapotranspiration than those receiving tap water. These results indicate that shrub species are likely to alleviate clogging and increase stormwater retention in biofiltration systems. However, shrubs with a high root diameter also had low total biomass and total root length and showed 33–51 % lower infiltration rates after sediment application compared with those receiving tap water. As all shrubs had higher root diameters than typical sedges and rushes, we suggest that shrubs need a combination of higher total biomass, total root length and average root diameter to effectively maintain infiltration. While shrubs which maintained infiltration had traits associated with high nutrient removal, nutrient removal efficiency of shrubs needs to be quantified. Although root traits were related to maintenance of infiltration, above-ground stems likely created flow pathways through sediment which requires further investigation. Overall, selecting shrub species with high total biomass has the potential to maintain infiltration and increase evapotranspiration in biofiltration systems impacted by high sediment loads.

The relationship between habitat heterogeneity and diversity can underpin design of urban spaces for biodiversity conservation. The area-heterogeneity trade-off hypothesis predicts that higher habitat heterogeneity should result in an increase in species richness but only up to a point, beyond which habitat micro-fragmentation leads to decreases in species diversity. However, the strength of area-heterogeneity trade-offs at small spatial scales is not well studied. We studied the relationship between avian diversity and habitat heterogeneity in 16 small urban parks across Hong Kong during the winter dry season across 2016 and 2017 (ten repeated surveys in total for each park). Habitat heterogeneity was assessed by measuring the evenness of microhabitat coverage of seven habitats as well as vertical canopy cover. In total, 12,973 individuals of 73 bird species were recorded in the study. Habitat heterogeneity had a small but negligible effect on total bird species richness or abundance. However, water coverage was positively related to total, intermediately rare and habitat specialist bird species richness, and shrub coverage was positively related to total and common bird species richness. These results demonstrate that environmental heterogeneity had little effect on avian species richness in urban green spaces at small spatial scales. We also found that microhabitat coverage can affect avian diversity and abundance, and these effects are specific to certain groups of bird species. When managing urban green spaces for biodiversity conservation in densely urbanized cities, a decrease in management disturbance (e.g. tree topping or pesticide application) will likely benefit avian species. Together with the fact that some locally uncommon species were observed throughout the study, capacity exists for environmental enhancement of these small urban parks to contribute to local avian conservation.

Audio-visual interactions play a crucial role in environmental perception. Incongruent audio-visual environments, although prominent in the urban fabric, have been underlit in research. Contrasting exposures to visually natural environments combined with urban sounds, as well as the reverse scenario of visually urban environments with natural sounds, are explored for their restorative potential, both at the cognitive level by means of self-reported evaluations and instinctively through measurements of electrodermal activity. The test panel (n=67) results point at a strong audio-visual urban-nature incongruency asymmetry. Eventful natural sounds in an urban setting were perceived as more pleasant and relaxing than eventful urban sounds in a green environment. So augmenting an urban environment with natural sounds, even in absence of any visual natural features, could be an interesting soundscape intervention. In contrast, a visually natural environment paired with urban sounds is strongly negatively perceived. The findings further contribute to a growing body of literature emphasizing the importance of the sonic environment in designing restorative spaces.

Atmospheric pollution threatens human health worldwide, with tropospheric ozone (O₃) and particulate matter (PM) among the most harmful pollutants. Urban trees can reduce the concentration of air pollutants through dry deposition on their canopies and stomatal uptake. At the same time, urban trees can deteriorate air quality by emitting aerosol- and O₃ precursors in the form of biogenic volatile organic compounds (BVOCs). O₃ and PM removal, and BVOC emissions vary depending on the tree species. Therefore, the diversity and spatial distribution of urban trees significantly influence their impact on local air quality. This study employs a dual approach to assess and map the impact of urban trees on air quality in Geneva, Switzerland. Firstly, we use the i-Tree Eco model combined with a tree inventory (237,191 trees) to quantify BVOC emissions and PM₁₀ (PM < 10 µm) and O₃ removal at the genus level. Secondly, we develop a species-level parameterization using 51 common urban tree species to estimate the same variables and ozone-forming potential (OFP). Results show that the tree density is heterogeneous in the study area, leading to neighborhoods with greater biomass and, therefore, stronger influence by trees on local air quality. According to i-Tree Eco, urban trees in Geneva emitted 50 t of BVOCs, while removing 14 t of PM₁₀ and 52 t of O₃ in 2014. With the species-level parametrization, we estimate that urban trees removed about 66 ± 55 t of PM₁₀ and 150 ± 96 t of O₃ in 2014. However, they could also emit about 130 ± 52 t of BVOCs annually, which, under favorable conditions, can form 1153 ± 519 t of O₃. Depending on the method, urban trees removed between 4 and 19 % of the anthropogenic PM₁₀ emissions. The annual removal rates are comparable to findings in other European cities. The disparities between the two approaches are due to different parameterizations. This study could help urban planners to select adequate species for future planting programs in Geneva and more generally. It showed that the impact of urban trees on air quality is spatially heterogeneous but significant, and tightly linked to the species composition.

Green roofs (GRs) are vital for shaping the material cycles of urban ecosystems as a form of distributed green infrastructure. However, current studies have predominantly focused on the material exchange between GRs and the urban environment, neglecting the internal distribution and equilibrium of constituent elements. By monitoring carbon (C), nitrogen (N), and phosphorus (P) in Sedum lineare Thunb and four substrates throughout the seasons, this study analyzes the ecological stoichiometric characteristics of an extensive GR in Nanjing, China. Intra-annual ratios of C:N (46.02, 13.38, 15.40), C:P (252.41, 57.85, 47.22), and N:P (5.75, 4.23, 3.84) were identified in the plant, substrate, and substrate microbial biomass, respectively. The intra-annual ratios of plant to substrate C, N, and P were roughly 9:1, 7:3, and 6:4, respectively. The use of different substrates resulted in significant variations in plant C, N, and P levels and their quantitative ratios, leading to distribution differences of these elements. Furthermore, substrate C, N, and P levels exhibit a generalized threshold effect on microbial biomass and plant C, N, and P concentrations. Notably, the substrate demonstrates an organic C sink potential of 7.11 g/kg/season, surpassing that of plants in unit mass. These findings contribute to understanding the distribution and dynamics of C, N, and P elements within extensive GRs.

Increasing heat in urban environments has recently become one of the most dangerous climate hazards due to its adverse impacts on urban populations. Implementing street-level trees could be an effective strategy to mitigate pedestrian heat exposure, particularly due to their ability to block incoming solar radiation. In this study, the PALM model system was applied to simulate the effects of a tree canopy and its location on heat exposure, as quantified by the Universal Thermal Climate Index (UTCI), during a heat wave, using the example of Prague-Dejvice, Czech Republic. Our results show that trees reduce the UTCI under their canopy by 3.5 °C on average, with the greatest UTCI reduction in open spaces during mornings and afternoons. High spatio-temporal variations in the reduction of UTCI by a tree canopy were observed in the study domain, especially in street canyons and courtyards. The effectiveness of trees in mitigating heat exposure was found to be closely related to their individual location with respect to surrounding buildings, specifically: (i) the distance from the nearest building, (ii) the height of the nearest building, and (iii) the azimuthal angle of the vector from the nearest building towards the tree. Model simulations indicate that a particularly small reduction in UTCI (about 2.5 °C less than the mean) can be found under trees located in the shade of taller buildings that are within a few metres and between southwest and southeast of the trees. Our findings illustrate that tree positioning in cities should be undertaken carefully and thoughtfully so that the presence of trees effectively improves thermal comfort and urban quality of life.

Historic gardens are conceptualized within various cultural and legal frameworks. This research aims to unravel the complexities of the historic garden identity through the lens of international regulations, national laws, and scientific literature to reveal differences in the perception of their botanical elements. We employed a combined analytical approach, using recommendations from related international institutions (i.e. UNESCO, ICCROM, and ICOMOS), national legislation, and a review of scientific literature. The analysis identified 25 documents related to the keywords: nature, landscape, site, and garden; however, only six mentioned gardens, and just one (The Florence Charter., 1982) explicitly addressed historic gardens. Only 7 % of UNESCO member countries (197) have specific provisions for historic gardens. Within them, a diverse range of definitions and standards has resulted in discrepancies in how historic gardens are recognized and conserved across different jurisdictions. Some countries have well-defined categories for garden heritage, while others offer limited or broad categorizations that may obscure garden identities. The findings underscore the necessity for more coherent international regulations that adequately reflect historic gardens' cultural and botanical significance. The study also highlighted the overlooked role of botanical elements, since only four countries included botanical value as an explicit criterion in their legal designations, suggesting that the botanical aspect is often considered within a larger ecological and geographical context. The imperative to preserve these living legacies within the broader context of cultural heritage also became apparent.