Relation between leaf area index and ndvi for subarctic deciduous vegetation

International Journal of Remote Sensing. 2020. Vol. 41. No. 20. P. 8573–8589.

Rees W. G., Golubeva E. I., Tutubalina O. V., Zimin M. V., Derkacheva A.

We consider the relationship between leaf area index (LAI) and normalized difference vegetation index (NDVI) for green-leaf vege- tation from a subarctic study site, specifically to test whether rela- tionships optimized for lower-latitude vegetation can be assumed to hold at higher latitudes. We focus attention particularly on dwarf- shrub vegetation, which has received little previous investigation. We have collected hyperspectral measurements of the optical prop- erties (reflectance and absorptance) of single leaves from dwarf shrub and tree species common to northern European Russia, and have developed a simple physical model of the properties of assemblages (‘leaf stacks’) of these leaves. The model is shown to provide a satisfactory explanation of the effect of varying the number of leaves in a stack on its NDVI, and can be easily adapted to make simple measurements using relatively inexpensive equip- ment. Our results show that the LAI-NDVI relationship for a vegetation canopy will saturate (approach within 10% of its limit- ing value) when the LAI reaches a value of around 2 to 3. Values this low are not uncommon in subarctic vegetation. It is also shown that dwarf shrub vegetation may show lower NDVI than trees for the same LAI.

Keywords: Арктика, Arctic, растительность, vegetation, satellite images, спутниковые снимки и аэрофотоснимки, vegetation index, вегетационный индекс