Urban Forest Types Research Articles

Carbon storage and sequestration by urban forests in Shenyang, China

Urban forests can play an important role in mitigating the impacts of climate change by reducing atmospheric carbon dioxide (CO2). Quantification of carbon (C) storage and sequestration by urban forests is critical for the assessment of the actual and potential role of urban forests in reducing atmospheric CO2. This paper provides a case study of the quantification of C storage and sequestration by urban forests in Shenyang, a heavily industrialized city in northeastern China. The C storage and sequestration were estimated by biomass equations, using field survey data and urban forests data derived from high-resolution QuickBird images. The benefits of C storage and sequestration were estimated by monetary values, as well as the role of urban forests on offsetting C emissions from fossil fuel combustion. The results showed that the urban forests in areas within the third-ring road of Shenyang stored 337,000t C (RMB92.02 million, or $ 13.88 million), with a C sequestration rate of 29,000t/yr (RMB7.88 million, or $ 1.19 million). The C stored by urban forests equaled to 3.02% of the annual C emissions from fossil fuel combustion, and C sequestration could offset 0.26% of the annual C emissions in Shenyang. In addition, our results indicated that the C storage and sequestration rate varied among urban forest types with different species composition and age structure. These results can be used to help assess the actual and potential role of urban forests in reducing atmospheric CO2 in Shenyang. In addition, they provide insights for decision-makers and the public to better understand the role of urban forests, and make better management plans for urban forests.

Species diversity of four major urban forest types under extreme climate conditions in Erzurum, Turkey

Plants in open green spaces play a vital role in environmental and aesthetic improvement of cities. Such spaces can improve the quality of life in cities, such as Erzurum, which are under severe social and physical stress due to the prevalent harsh climatic conditions. The objective of this study was to identify the woody plant species and their frequency and amenity functions in four urban forest types in Erzurum. A total of 33,381 woody plants (72.3% trees, 27.7% shrubs) were examined: 44.9% in the grounds of public institutions; 30.8% along roadsides; 14.8% in city parks; and 9.5% in home gardens. Overall, 73 woody plant species were identified. Pinus sylvestris was the most frequent tree, followed by Betula verrucosa, Acer negundo and Fraxinus americana; while among the shrubs, Ribes aureum was most frequent, followed by Spirea vanhouttei, Rosa canina and Syringa vulgaris. Institutional grounds had the largest diversity and number of woody plants, followed by home gardens, city parks and roadsides. The majority (83.3%) of trees were deciduous species. The identified species belong to 24 families: 15 tree families and 12 shrub families. While dominant trees were evenly divided between native and exotic species, 71% of dominant shrub species were exotic.

Exotic vascular plant invasiveness and forest invasibility in urban boreal forest types

The riverine forests of the northern city of Edmonton, Alberta, Canada display strong resilience to disturbance and are similar in species composition to southern boreal mixedwood forest types. This study addressed questions such as, how easily do exotic species become established in urban boreal forests (species invasiveness) and do urban boreal forest structural characteristics such as, native species richness, abundance, and vertical vegetation layers, confer resistance to exotic species establishment and spread (community invasibility)? Eighty-four forest stands were sampled and species composition and mean percent cover analyzed using ordination methods. Results showed that exotic tree/shrub types were of the most concern for invasion to urban boreal forests and that exotic species type, native habitat and propagule supply may be good indicators of invasive potential. Native forest structure appeared to confer a level of resistance to exotic species and medium to high disturbance intensity was associated with exotic species growth and spread without a corresponding loss in native species richness. Results provided large-scale evidence that diverse communities are less vulnerable to exotic species invasion, and that intermediate disturbance intensity supports species coexistence. From a management perspective, the retention of native species and native forest structure in urban forests is favored to minimize the impact of exotic species introductions, protect natural succession patterns, and minimize the spread of exotic species.

Forest type affects predation on gypsy moth pupae

Abstract 1 Predation by small mammals has previously been shown to be the largest source of mortality in low‐density gypsy moth, Lymantria dispar (L.), populations in established populations in north‐eastern North America. Fluctuations in predation levels are critical in determining changes in population densities.2 We compared small mammal communities and levels of predation on gypsy moth pupae among five different oak‐dominated forest types along this insect's western expanding population front in Wisconsin. Comparisons of predator impact can provide critical information for predicting variation in susceptibility among forest types.3 The results indicated that small mammals caused more mortality than did invertebrates.4 Both abundance of Peromyscus sp. predators and predation levels were lower in urban and xeric forest types than in mesic sites.5 These results suggest that, because predation pressures will probably be greater in the mesic sites, gypsy moths may be less likely to develop outbreaks in these habitats, and that defoliation will probably be more frequent in urban and xeric oak‐dominated sites.

아까시나무림의 군락분류와 군락생태

아까시나무 우점림의 식생유형에 대한 분류와 분포양식 그리고 생태식물상적 특성을 규명하였다. 전통적인 식물사회학적 방법과 식생조사자료 및 식생유형간의 유사성 분석을 위하여 주좌표분석법(Principal Coordinates Analysis)과 상관 계수(correlation coefficient)가 이용되었다. 생태식물상의 분석에는 출현 식물종들의 특질(넌출형, 일이년생 생명환, 삼림식생요소, 체감도시화지수)이 이용되었다. 이러한 분석은 출현종의 상대기여도를 바탕으로 하는 입지-식생조사구 매트릭스의 식물군락표 및 군락합성표를 토대로 이루어졌다. 아까시나무 우점림은 총 77과 193속 323종으로 이루어져 있었으며, 아까시나무-닭의장풀군집(전형아군집, 떡갈나무아군집, 자귀나무아군집, 소나무아군집, 굴참나무아군집, 가중나무아군집), 아까시나무-갈대군락(전형하위군락, 띠하위군락)으로 분류되었으며, 크게 네 가지 식생형(도시형, 농촌형, 하천형, 복합형)으로 구분되었다. 아까시나무-닭의장풀군집은 졸참나무-작살나무아군단의 냉온대 남부 저산지대의 아까시나무 조림식생을 대표하는 식생단위이며, 아까시나무-갈대군락은 하천(정수역)형으로 기재되었다. 가중나무아군집은 높은 체감도시화지수에 의하여 도시형 아까시나무림으로 규정되었다. 하천형을 제외한 우리나라의 아까시나무 우점림은 지속군락으로 고려되었다. The black locust (Robinia pseudoacacia L.) forests were studied by a phytosociological approach. Particular attention was given to characterize the vegetation classification, distribution pattern, and ecological flora of the syntaxa classified. A total of 38 releves were analyzed by using Correlation coefficient, UPGMA as the clustering method, and Principal Coordinates Analysis for ordination. Ecological flora analyzed by plant character sets such as scrambler, annual and biennial plants, forest elements, and actual urbanization index. The analyzed data are based on site-releve matrix with relative net contribution degree (r-NCD) of species. A total of 77 families, 193 genera and 323 species of vascular plants are recorded. Camellino-Robinietum pseudoacaciae ass. nov. and Phragmites-Robinia pseudoacacia community were described. Main cluster and ordination could be separated: 1) urban type, 2) rural type, 3) riparian type, and 4) combined type. It is defined that the Robinietum is a representative unit on the black locust afforestation, Phragmites-Robinia community on the lentic zone in the river ecosystem, and Cameliino-Robinietum ailanthetosum altissimae as an urban forest type. The Robinietum was considered as a perpetual community.

Heterogeneity and differentiation of the tree flora in three major land uses in Guangzhou City, China

The tree flora of humid-tropical Guangzhou city in south China was studied to understand its composition and variations. Aerial photographs identified three major urban-forest types in three land uses: institutional, park and roadside. Data on 115 064 trees in 246 species were statistically analyzed. Park and roadside areas have lower species richness than institutional forest. Park habitat has re- latively more rooms for species, biomass and floral enrichment. Roadside leads in tree density with full utilization of plantable space, whereas institutional forest has the highest species density index and the most rare natives. Commonality of species amongst forests li- mits to 91 species, with park and institutional sharing 68 species, and road sharing merely 8 and 1 species respectively with institutional and park. Institutional forest has distinct composition and character, with less domination by popular species and more solitary or rare species. Native species exceed exotics at roadside; institutional and park have a reverse trend. Practical implications for urban-forest ma- nagement are discussed.

Species diversity of three major urban forest types in Guangzhou City, China

Guangzhou city in South China was assessed to understand the associations between tree species diversity and urban development. The study area covers five urban districts which form the bulk of the built-up areas. Reconnaissance field trips and aerial photograph survey identified main green covers in three urban-forest types, namely roadside niches, urban parks, and institutional grounds. Trees at roadsides and 21 parks were censused, whereas 14 large institutional sites were sampled. A total of 115,140 trees were evaluated for species identification, dimensions and site-environs conditions, with 40.8% at roadsides, 38.2% in parks, and 21.0% in institutional grounds. The urban forests composed of 254 species in 62 botanical families led by Moraceae, Caesalpiniaceae and Myrtaceae. Institutional forest has the highest diversity, followed by park and roadside trees. Most trees are derived from a small group of dominant species. Broadleaf species are prominent, especially the evergreen, whereas conifers and palms are sparingly adopted, except palms in institutional areas. Exotic species, mainly originating from tropical Asia and Australia, are common but not as dominating as in other tropical cities. Native species include spontaneous invasion into ruderal habitats, especially in parks. Species composition was interpreted vis-à-vis the interplay of natural and cultural factors then and now. Changing site conditions (geometric vs. physiological attributes), decision-making and management regimes (official-public vs. individual-lot stewardship), funding constraint (straitjacketed vs. adequate), intended amenity functions, and evolving landscape fashion (traditional vs. innovative), have helped to mould respective species assemblages to define their identity. Implications for long-term tree planning and management in Guangzhou and other fast developing cities are explored.

CLASSIFICATION OF URBAN FORESTS IN THREE U.S. CITIES: A TEST OF MOLL'S URBAN FOREST ZONE MODEL

Summary Cluster analysis, using urban forest configuration variables, was used to classify census tracts in three U.S. cities: Waterbury, Connecticut; Pueblo, Colorado; and Eugene, Oregon. The resulting classification indicates that tracts in each city can be grouped into four categories: inner city tracts characterized by small average tract size and small amounts of space for growing vegetation; transitional tracts with increased amounts of growing space; residential tracts with large amounts of herbaceous cover and growing space; and suburban tracts characterized by large average tract size and large amounts of growing space. Differences within these groups among the cities can be attributed to different patterns of development and differences in potential natural vegetation. Broad similarities among the three cities with very different development histories, indicate that simplified models of urban spatial structure correspond to general urban forest types. These urban forest types can be used to develop management options for vegetation and associated resources in urban areas.