Leaf area measurements of urban woodlands, parks and trees in Gothenburg, Sweden

• Leaf area of urban vegetation is an important characteristic since it influences e.g. the urban climate through transpiratory cooling, air quality through air pollutant deposition and water management through rainfall interception. Measurements of leaf area are fundamental to accurately model these processes. Few studies have however presented leaf area measurements in the urban environment. The aim of this study was to i) describe the urban greenery based on measurements of leaf area index (LAI) of trees in different types of urban environments and ii) compare two different methods to measure LAI of urban trees. During the summer of 2014, LAI was measured in a central urban deciduous woodland, a suburban mixed forest, a central old park, a grove adjacent to a traffic route and in allotment gardens in Gothenburg, Sweden. In addition, single urban trees of seven common urban tree species in Gothenburg were measured (Acer platanoides, Aesculus hippocastanum, Betula pendula, Fagus sylvatica, Prunus serrulata, Quercus robur and Tilia europaea). Two different indirect methods were used; the LAI-2200 plant canopy analyzer (Li-cor Inc.) and hemispherical photography. The digital images were analyzed with Hemisfer (Schleppi, WSL). The canopy measurements were performed in a grid or cross with 8-32 points with fixed intervals. For single urban trees, 3-6 specimen of each species was measured. Average LAI of the measured urban parks and forests ranged between 2.6 and 4.8. A better way to characterize the different sites was to use cumulative density functions, which visualized the degree of heterogeneity. The old urban park had the largest LAI range (0 - 8.3). As a comparison, LAI ranged from 2.4 to 5.9 in the more homogenous urban woodland. LAI based on hemispherical photos was similar to the values received by the LAI-2200 plant canopy analyzer. Both methods had advantages and disadvantages. The urban environment offers challenges not present in forest canopies, such as interference of buildings. A combination of methods might be necessary for an environment as heterogeneous as the urban, with both single trees and forest canopies.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

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