Characteristics of the urban forests in arctic and near-arctic cities

The urban forest of three arctic and near-arctic cities (Murmansk in Russia, Nuuk in Greenland, and Reykjavik in Iceland) were surveyed to determine tree species composition and structure. Interviews with local authorities were conducted to learn about the history of urban tree planting. The urban forests of all three cities were composed of a limited number of trees and tree species due to abiotic constraints of the arctic and near-arctic environment. These limitations include: low temperature, short growing season, high wind velocity and permafrost. A total of 28 species were observed in the three cities. Only three of these (Alnus incana (L.) Moench, Picea abies (L.) Karst., Betula pubescens Ehrh., and Salix glauca L.) were observed in all three of the cities. Planting designs that created windbreaks for pedestrians were common along streets in Murmansk and Reykjavik. Street trees have not yet been introduced in Nuuk, but trees were found in cemeteries, parks, and on private property. Older portions of cemeteries in all three cities were characterized by trees planted directly on graves. These grave trees were the first trees to be introduced in these cities. Subsequently, ‘trial and error’ was used by local residents to plant trees. Much of these plantings failed. In recent times arboreta were established near all three cities to identify species suited for planting under arctic and near-arctic conditions. Trees identified in these test gardens are now being planted in Murmansk and Reykjavik.     

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area of the Korean peninsula, and compared this to the historical list of species found in these areas by consulting historical documents and old illustrations.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.     

Social disparities in tree canopy and park accessibility: A case study of six cities in Illinois using GIS and remote sensing

Easy access to green space and the presence of lush tree canopy in neighborhoods provide substantial psychophysical benefits to residents. However, these urban amenities are often unevenly distributed between white and racial/ethnic minority residents. In this study, we investigated racial/ethnic disparities in access to parks and tree canopy using a geographic information system (GIS) and remote-sensing techniques in six Illinois cities. An accessibility index based on a new Google Maps application programming interface (API) was used to calculate walking distances between points of origins and parks, and integrated classification techniques were applied to calculate the amount of tree canopy. Kernel-smoothing function was applied to both canopy and park layers to transform point value to continuous surface value. Both ordinary regression and spatial regression were used to find the relationship.The results of this study show that racial/ethnic minorities have less tree canopy in their neighborhoods, but it did not find significant differences in terms of access to parks. Spatial regression was determined to be an effective modeling approach for the data used in this study. Methods used in this study can be extended to study accessibility to various destinations using different means of transit, and the results can guide intervention programs to help reduce environmental inequity.     

Detection of unfavourable urban areas with higher temperatures and lack of green spaces using satellite imagery in sixteen Spanish cities

This paper seeks to identify the most unfavourable areas of a city in terms of high temperatures and the absence of green infrastructure. An automatic methodology based on remote sensing and data analysis has been developed and applied in sixteen Spanish cities with different characteristics. Landsat-8 satellite images were selected for each city from the July-August period of 2019 and 2020 to calculate the spatial variation of land surface temperature (LST). The Normalized Difference Vegetation Index (NDVI) was used to determine the abundance of vegetation across the city. Based on the NDVI and LST maps created, a k-means unsupervised classification clustering was performed to automatically identify the different clusters according to how favourable these areas were in terms of temperature and presence of vegetation. A Disadvantaged Area Index (DAI), combining both variables, was developed to produce a map showing the most unfavourable areas for each city. Overall, the percentage of the area susceptible to improvement with more vegetation in the cities studied ranged from 13 % in Huesca to 64–65 % in Bilbao and Valencia. The influence of several factors, such as the presence of water bodies or large buildings, is discussed. Detecting unfavourable areas is a very interesting tool for defining future planning strategy for green spaces.     

Comparing the carbon sequestration capacity of temperate deciduous forests between urban and rural landscapes in central Japan

Urbanisation is increasing tremendously in some parts of the world. Consequently, many rural forests may become depleted, although many opportunities exist for urban forests to increase. However, few studies have quantified the carbon (C) sequestration capacities of urban and rural forests in specific climatic zones. The present study compared carbon sequestration in two temperate deciduous forests located in Nagoya and Toyota, central Japan. The Nagoya University forest represented an urban forest, and a site in Toyota represented a rural forest. The urban forest at Nagoya University had comparatively smaller areas of green space and larger areas of buildings and roads. Land uses for building and road, which are typical of urban areas, result in smaller diurnal temperature ranges but higher air temperature, vapour pressure deficit, and atmospheric carbon dioxide (CO₂) concentration. The urban forest in this study exhibited higher gross ecosystem exchange (GEE), especially in the active growing season from May to September, suggesting the possible effect of CO₂ fertilisation. However, higher air temperatures caused comparatively smaller net ecosystem exchange (NEE) because of higher ecosystem respiration (RE). Although both forests functioned as CO₂ sinks at annual time scales, the rural Toyota forest site (5.43 t C ha^–1 yr^–1) had 36% higher net ecosystem production (NEP=–NEE; the negative sign indicates uptake by the forest ecosystem from the atmosphere) than that at the urban forest. The higher normalised respiration (i.e., RE/GPP ratio; GPP=–GEE where GPP represents gross primary production) at the Nagoya University forest might be attributable to factors associated with the degree of urbanisation. Thus, in temperate forests, factors associated with urbanisation may reduce the atmospheric carbon sink function by accelerating respiration. This is an issue of global interest, as many countries are experiencing rapid urbanisation.     

The temporal trend of urban green coverage in major Chinese cities between 1990 and 2010

Information on changes in urban green spaces and the causes of these changes is important for urban planning. In this study the trends of urban green coverage (UGC) between 1990 and 2010 in 30 major Chinese cities were studied using classified Landsat satellite images. Associations between the trends and natural and socio-economic variables were analyzed using the maximum information-based nonparametric exploration method. The results showed that, overall, the studied cities have become greener over the past two decades. Greening in old city districts and expanded built-up areas (BUAs) led to the increase of urban green coverage at a mean annual rate of 1.51%. However rapid urbanization also caused a dramatic turn-over in vegetation covers. On a regional scale, around 46.89% of original vegetation cover was converted to other land cover types. The trends of UGC cannot be attributed to any one of natural or socio-economic variables alone. The combined influences of economic growth, climate change, and urban greening policies are the most likely causes behind the detected trend. One lesson from this study is that the preservation of existing vegetation cover must be a priority in urban greening programs.     

Urbanization pressures on the natural forests in Turkey: An overview

Forests used to be the main field of interest for rural communities, but now they attract the attention of urbanites too. The forest–public relationship is important as forests protect water resources, preserve the soil and increase its productivity, provide positive effects on climate and health in general, and can be used for recreation and tourist purposes. This study aims at assessing how the current rapid urbanization process in Turkey affects forests. Urban requirements such as biomass for heating, education facilities, settlements, recreation, tourism and employment exert various pressures on the forest. In this study we assessed these pressures and suggest that forest legislations should be developed to respond to expectations of urbanites from forests, new recreation areas should be developed and urbanites’ interest in and knowledge of the forests should be increased, where all social groups including the forestry authority should work together.     

Urban forests and social inequality in the Pacific Northwest

Research has shown there is a positive relationship between urban greenness and the well-being of city residents. But greenness is often unevenly distributed across a city, raising environmental justice issues. In 2011 and 2012 the USDA Forest Service, Forest Inventory and Analysis program installed ground plots in the urbanized areas of Oregon and Washington. We analyze these data for the urban areas west of the Cascade Mountains, linking it with demographic data from the U.S. Census to examine the relationship between greenness and socioeconomic status at a sub-regional scale. To explore some relations between urban forest measures and socioeconomic conditions and measures we developed four models: presence of tree canopy cover with a logistic mixed model, and on a subset of the data, percent tree canopy cover with a linear mixed model and tree count and tree species count with Poisson mixed models. We found that median household income, house value, land use, and years in the Tree City USA program contributed to explaining measures of greenness, such as canopy cover presence, percent canopy cover, tree counts, and tree species counts. This agrees with other studies, but does so at a broad scale covering the most densely populated areas in the Pacific Northwest.     

The association between plant diversity and perceived emotions for visitors in urban forests: A pilot study across 49 parks in China

Urbanization introduces uncertainties to the biodiversity of plant communities. The perception of biodiversity can be associated with positive mental health and well-being, but direct evidence is still insufficient. In this study, we collected data about plant biodiversity assessments from studies on urban forests in the literature of China’s national knowledge infrastructure. Records of the species amount, Shannon index, and Simpson index were extracted from 49 urban forest parks in 13 cities across mainland China from 2018 to 2021. A total of 1938 facial photos were obtained from microblogs with check-in locations at these parks in the Sina Microblog in 2020. Happy, sad, and neutral emotions and positive response index (PRI; happy minus sad) were rated and mapped for spatial distributions. The amount of species was distributed as a heterogeneous pattern for all plant types, and biodiversity was higher in the northern regions (e.g., ~55% in Qingdao and over 50% in Taiyuan) than in southern cities along the Yangtze River (e.g., ~35% in Huaihua and Changsha). Trees did not account for the association of biodiversity with emotional expressions. Smiles were elicited mostly in parks with more diverse shrubs (Shannon index: R=0.4335; P = 0.0029) and herbs (R=0.6162; P = 0.0008). Females showed more smiles than males (47% vs. 32%, respectively; F=39.15, P < 0.0001), and happy emotions tended to be higher in older visitors (senior vs. younger: 58% vs. 43%, respectively; F=2.72, P = 0.0280). Overall, we recommend visiting parks in northern cities of China for the benefit of evoking positive emotions through experiencing abundant undergrowth species. Female visitors would benefit more than males in the promotion of mental well-being by perceiving diverse shrubs and herbs in urban forest parks.     

Epiphyte communities in Mediterranean fragmented forests: importance of the fragment size and the surrounding matrix

Context

Mediterranean forests have been fragmented intensively over time, thereby yielding small and isolated forest remnants. They host a rich variety of epiphytes, which may be affected by landscape structure. Previous studies have analyzed the influence of habitat quality on these epiphytic communities, but there is little knowledge of the effects of other fragment features.

Objectives

We evaluated the impacts of forest loss and fragmentation on epiphytic communities (lichens and bryophytes) at plot and fragment scales after controlling the variation in forest structure and management.

Methods

We considered 40 fragments of dense oak forests in a human-modified landscape. We quantified their spatial attributes (size and shape), the quality of the surrounding matrix and the forest stand structure. We modeled community traits, and the presence and abundance of species at fragment and plot scales.

Results

Fragment size, shape, and the quality of the surrounding matrix were key factors that affected epiphytic richness and diversity. Larger and more regularly shaped fragments hosted the richest and most diverse communities, possibly offering a larger core area and thus favoring the entry of typical forest species. A high-contrast matrix was only favorable in small fragments, probably allowing the arrival of propagules. The species-level response was highly variable.

Conclusions

Landscape structure provides powerful explanations of the richness and diversity losses among epiphytes. Forest management should ensure the retention of the largest possible continuous forests. The management strategy of the matrix will depend on the conservation goal, since we observed different effects related with quality and fragment size.

     

Linking ecological condition and the soundscape in fragmented Australian forests

Natural landscapes are increasingly subjected to anthropogenic pressure and fragmentation resulting in reduced ecological condition. In this study we examined the relationship between ecological condition and the soundscape in fragmented forest remnants of south-east Queensland, Australia. The region is noted for its high biodiversity value and increased pressure associated with habitat fragmentation and urbanisation. Ten sites defined by a distinct open eucalypt forest community dominated by spotted gum (Corymbia citriodora ssp. variegata) were stratified based on patch size and patch connectivity. Each site underwent a series of detailed vegetation condition and landscape assessments, together with bird surveys and acoustic analysis using relative soundscape power. Univariate and multivariate analyses indicated that the measurement of relative soundscape power reflects ecological condition and bird species richness, and is dependent on the extent of landscape fragmentation. We conclude that acoustic monitoring technologies provide a cost effective tool for measuring ecological condition, especially in conjunction with established field observations and recordings.     

Tropical deforestation and species endangerment: the role of remote sensing

Initial results of a pilot study to link remotely-sensed information on tropical forest loss to field-based information on species endangerment are reported here. LANDSAT multispectral scanner (MSS) imagery from 1973 and 1988 were used to estimate net forest removal (29% of forest area), regrowth (7% of forest area, including possible artifactual errors), and forest edges in Mabira Forest in southeastern Uganda during the 15-year period. Of the forest remaining, the percentage that was heavily disturbed increased from 18% to 42%. This change in forest density was observable with the MSS imagery. The total forest edge-to-area ratio (including edges interior to the forest boundary) increased by 29% over the period. Although four distinct types of closed tropical forest, based on structure or dominance, could be recognized on the ground, the types could not be distinguished by differences in spectral reflectance in the four MSS bands. Closed tropical forest could be readily distinguished from exotic conifer plantations, banana plantations, and other non-forest vegetation types. Field measurements in Mabira and other Ugandan rain forests, and in rain forest isolates on the Atherton Tableland of North Queensland, are being made to relate changes in forest fragmentation to resulting changes in species abundance, structural form of the forests, and morphological diversity of target populations. Possible applications of conservation biology theory and modeling to these data are briefly discussed.     

Vacant lots: An underexplored resource for ecological and social benefits in cities

Vacant lots make up a large proportion of urban land and are of interest to many stakeholder groups. While they are often viewed as dangerous or unsightly, they can be an economic, social, and ecological resource. Here we present a literature review focused on restoring biodiversity in vacant lots, emphasizing the intersection of human and wildlife needs. We focus on the benefits, challenges, and processes of restoration in vacant lots and synthesize ecological, social, and economic information across these domains. We suggest that fast, inexpensive restoration techniques could be implemented in vacant lots and would be well suited to increasing greenspace in low-income areas. Furthermore, we emphasize that land managers, ecologists, sociologists, urban planners, and local communities must work together to conceptualize, carry out, and monitor restoration projects, as these projects are often characterized by disparate goals and insufficient follow-up. Vacant lot restoration is best addressed by an interdisciplinary approach that combines economic, social, and environmental needs and concerns into a holistic urban land use paradigm.     

Modelling the spread of tree pests and pathogens in urban forests

Understanding the potential dynamics of tree pests and pathogens is a vital component for creating resilient urban treescapes. Epidemiologically relevant features include differences in environmental stress and tree management between street and garden trees, and variation in the potential for human-mediated spread due to intensity of human activity, traffic flow and buildings. We extend a standard spatially explicit raster-based model for pest and pathogen spread by dividing the urban tree population into roadside trees and park/garden trees. We also distinguish between naturally-driven radial spread of pests and pathogens and human-mediated linear spread along roads. The model behaviour is explored using landscape data for tree locations in an exemplar UK town. Two main sources of landscape data were available: commercially collated aerial data, which have high coverage but no information on species; and, an urban tree inventory, with low, non-random, coverage but with some species data. The data were insufficient to impute a species-specific host landscape accurately; however, by combining the two data sources, and applying either random or Matérn cluster point process driven selection of a subset of all trees, we create two sets of potential host landscapes. We find that combining the two mechanisms of dispersal has a non-additive effect, with the enhanced linear dispersal enabling new foci of infection to be established more rapidly than with radial dispersal alone; and clustering of trees by species slows down the expansion of epidemics when compared with random distribution of tree species within known host locations.     

Intensive recreational activities in suburban forests: A method to quantify the reduction in timber value

Central European forests are generally multifunctional; the same forest areas are used for timber production and recreation. In frequently visited areas damage to trees can be observed. We developed a method to estimate the actual reduction in timber value due to recreation-induced damage. The method was tested in two suburban (oak–hornbeam and beech) forests sustainably maintained by a selective management system and with free access in northwestern Switzerland. Considering the total forest areas, 9.4% of oak trees and 23.0% of beech trees were damaged by recreational activities. The resulting reduction in timber value averaged 19 and 53 € ha^?1 a^?1 in the two forests. The annual reduction in timber value due to recreation-induced damage can account for up to 16% of the total proceeds. The monetary benefits of forest recreation in these areas, however, by far exceed the damage to trees.     

Managing green spaces of the deceased: Characteristics and dynamics of Danish cemetery administrations

Cemeteries in Denmark are managed by the national church; they are green spaces of high standard, with an important role as burial places for members of the society. Previous studies elsewhere indicate that cemetery management operates with special approaches on the fringe of other public service organisations. To gain a better understanding of cemetery administration, this paper will characterise cemetery management and in particular different types of cemetery administration in the national church of Denmark. A case study of 28 cemetery administrations was conducted, gathering key data about the cemeteries, and included 42 semi-structured interviews to address this question. The analyses indicated that the Danish cemetery administrations show traits similar to those found in previous studies. They are locally governed and marginalised from the rest of the local administration; they perceive themselves as unlike other administrations; and change is dependent on local initiatives, only occurring when necessary, but also with indications that cooperation in handling crises in the wider field do happen. The Danish cemeteries are categorised according to the constructs of urban and rural cemeteries and the conflicting logics of the cemetery as a static or a dynamic entity. Furthermore, the categorising can be related to the combination of utilisation of the grave areas and the adaptation of the cemetery site to local burial needs. This decouples, to some extent, economic performance from the efficiency of operation control and links it to strategic planning. The special traits of cemetery administration are associated with the special approaches and institutions that surround cemetery administration, because they are linked to the handling of the deceased. These two aspects seem appropriate for explaining the dissimilarity of cemetery administration from other public administrations and green space management in particular. Further research however is required.     

Three objectives of historical ecology: the case of litter collecting in Central European forests

Short- and long-term patterns of net ecosystem carbon balance (NECB) for small, relatively uniform forest stands have been examined in detail, but the same is not true for landscapes, especially those with heterogeneous disturbance histories. In this paper, we explore the effect of two contrasting types of disturbances (i.e., fire and tree harvest) on landscape level NECB by using an ecosystem process model that explicitly accounts for changes in carbon (C) stores as a function of disturbance regimes. The latter were defined by the average disturbance interval, the regularity of the disturbance interval (i.e., random, based on a Poisson frequency distribution, or regular), the amount of C removed by the disturbance (i.e., severity), and the relative abundance of stands in the landscape with unique disturbance histories. We used the model to create over 300 hypothetical landscapes, each with a different disturbance regime, by simulating up to 200 unique stand histories and averaging their total C stores. Mean NECB and its year-to-year variability was computed by calculating the difference in mean total C stores from one year to the next. Results indicated that landscape C stores were higher for random than for regular disturbance intervals, and increased as the mean disturbance interval increased and as the disturbance severity decreased. For example, C storage was reduced by 58% when the fire interval was shortened from 250 years to 100 years. Average landscape NECB was not significantly different than zero for any of the simulated landscapes. Year-to-year variability in landscape NECB, however, was related to the landscape disturbance regime; increasing with disturbance severity and frequency, and higher for random versus regular disturbance intervals. We conclude that landscape C stores of forest systems can be predicted using the concept of disturbance regimes, a result that may be a useful for adjusting estimates of C storage to broad scales that are solely based on physiological processes.     

Greening cities through urban planning: A literature review on the uptake of concepts and methods in Stockholm

Nature-based solutions (NBS) represent the most recent of several "greening" concepts proposed to support spatial planning and decision-making towards sustainable metropolitan regions. Despite similarities, the concepts stem from different disciplines and policy arenas and reflect various models of people-nature relations. This paper aims to analyze the uptake of greening concepts in scientific planning literature focusing on (urban) nature and landscape in the metropolitan region of Stockholm, Sweden, over the last three decades. It investigates what changes this evolution has brought in terms of the topics adopted, methods applied, and types of planning support put into practice. We identified 574 articles that reflect substantial research on greening concepts in the Swedish planning context. The articles demonstrate an initial prevalence of biodiversity with later increases of interest in ecosystem services and NBS. A detailed analysis of the studies focusing on Stockholm revealed Population growth/densification, Green space management and Biodiversity conservation as the most commonly addressed societal challenges. The most frequently mentioned type of green and blue element is Parks and (semi-)natural urban green areas, including urban forests. Methods applied were mostly quantitative, while mixes with qualitative approaches were only apparent in ecosystem services articles. Half of the studies involved practitioners or decision-makers, but only four seemed related to real-life planning processes. Taken together, the influence of scientific literature on the uptake of greening concepts in spatial planning seems to have been limited. Future mainstreaming of greening concepts in Stockholm and beyond could benefit from available data, methods and experiences, but will require more active translation and boundary management. Further research into science-policy-planning interfaces at city scale is thus imperative to advance more sustainable pathways for people and nature in metropolitan regions.