Onderzoeksproject SR/00/131 (Onderzoeksactie SR)
Atmosphere and soil conditions largely determine urban habitat quality. Nevertheless, hardly any integrator has been applied, describing urban atmospheric and soil pollution impacts. Biomonitoring of natural vegetation reflects long-term changes of environmental quality, because leaves account for the complex impacts of different air pollutants and accumulate pollution over the growing season.
The overall objective is to develop, test and validate a passive biomonitoring methodology based on airborne hyperspectral observations and on a field experimental approach which lapses over several spatial scales as well as over three structural and temporal levels. The specific objectives are:
- the estimation of the spatial distribution of the overall pollution of soil and air;
- The investigation at sub-leaf level of the spatial distribution, and seasonal evolution of leaf wettability, stomatal characteristics and chlorophyll fluorescence;
- The investigation at leaf level of the spatial distribution and seasonal evolution of specific leaf area, chlorophyll content, chlorophyll fluorescence and the red edge shift;
- The investigation at canopy level of fluorescence and the red edge shift;
- to compare and validate hyperspectral airborne measurements with these ground measurements for different species, time and test sites; and
- To describe and optimize a protocol for the estimation of urban habitat quality distribution with a high spatial resolution and based on airborne measurements.
Selection of the tree species and a minimum of 150 sampling points balanced over the different land use classes of the study areas Ghent and Valencia in order to optimize geostatistical analysis
- Characterization of soil and air quality at the sample sites based on existing soil quality data and ongoing monitoring of leaf magnetic properties
- Ground measurements at the sub-leaf level: leaf wettability as indicator of damage to the leaf surface, stomatal characteristics as indicator of environmental stress conditions, in vivo chlorophyll fluorescence measured with a portable „Plant Efficiency Analyser‟ system and a portable „pulsed amplitude modulated fluorometer
- Ground measurement at the leaf level: specific leaf area, relative chlorophyll content using a Chlorophyll Content Meter, chlorophyll fluorescence using a custom build (by Prof. Valcke) „Fluorescence Imaging System‟ will be measured and analysed using different (image analysing) techniques; Red Edge Position will be measured applying field spectrometry
- Airborne canopy level measurements (EUFAR network) on the same trees as field measurements: determination of REP based on the hypercubes and the investigation of REP between tree structural levels, derivation of natural chlorophyll fluorescence using the Fraunhofer Line Discrimination method
- Data-analysis and –validation at the considered tree structural levels
Description and optimisation of a sampling methodology for the estimation of urban habitat quality based on airborne data
The overall outcome of the project will be a primer in the demonstration of a methodology for the monitoring of urban habitat quality and urban air quality based on airborne hyperspectral and chlorophyll fluorescence measurements. It is to be expected that the developed methodology will need further testing and validation after this project, but at least we hope to establish a solid scientific basis for further development.
The scientific outcome of the project will be a thorough knowledge of the correlation between tree characteristics at the sub-leaf, leaf and canopy level with air and soil pollution. Moreover, there will be a deep knowledge of the correlation between the characteristics measured at the different tree levels, and especially on the relevance and potential of airborne hyperspectral and chlorophyll fluorescence data.