Assessing urban habitat quality using spectral characteristics of Tilia leaves.

Monitoring environmental quality in urban areas is an important issue offering possibilities to control and improve urban habitat quality as well as to avoid adverse effects on human health. A tree leaf reflectance-based bio-monitoring method was used to assess the urban habitat quality of two contrasting habitat classes in the city of Gent (Belgium). As test trees, two Tilia species were selected. Custom made Matlab code is applied to process the measurements of leaf reflectance. This enables the discrimination between polluted and less polluted habitats. The results elicit, that leaf reflectance in the PAR range, as well as the NDAI (Normalised Difference Asymmetry index) are species dependent while Dorsiventral Leaf Reflectance Correlation (DLRC) seems to be independent of species. Therefore the assessment of urban habitat quality is perfectly feasible using leaf reflectance, when taking account of the species specificity of tree leaf physiological and structural responses to habitat quality.

Dorsi-ventral leaf reflectance properties of Carpinus betulus L.: an indicator of urban habitat quality.

The objective of this paper is to give an account of the evaluation of the effect of urban habitat quality on dorsi-ventral leaf reflectance asymmetry to bio-monitor urban habitat pollution. Reflectance in the RGB bands of a reflex camera is measured at the adaxial and abaxial sides of Carpinus betulus L. leaves for two contrasting urban habitats, e.g.; suburban green and industrial habitats in the city of Gent (Belgium). Abaxial leaf reflectance is consistently higher than adaxial leaf reflectance. We quantified leaf dorsi-ventral reflectance asymmetry with a newly defined Normalized Dorsi-ventral Asymmetry Index (NDAI). The NDAI is significantly higher in industrial habitats as opposed to suburban green ones. Our optical observations indicate that changes in Carpinus betulus L. leaf morphology are related to urban habitat quality. Hence, we suggest that leaf dorsi-ventral reflectance asymmetry allows the estimation of the magnitude and spatial extent of environmental pollution in urban environments.