A field-portable instrument for mapping the micro-environment within grass canopies

A battery-operated field-portable instrument designed to measure the ratio of red/infra-red (R/IR) light beneath grassland canopies on a micro-scale is described. Because the ratio is correlated with leaf area index, a grid of ratio measurements may be used to map the location and size of canopy gaps. These are potential entry points into the vegetation for new individuals and for new species of plants. Measurements are made with a 1.5 mm diameter fibre optic probe which scans beneath the canopy under the control of a portable microcomputer. Data are stored on magnetic tape and processed by mainframe computer to produce contour maps of R/IR ratio.