|Digital false colour aerial photographs for discrimination of aquatic macrophyte species|Valta-Hulkkonen, K.; Pellikka, P.; Tanskanen, H.; Ustinov, A.; Sandman, O. (2003). Digital false colour aerial photographs for discrimination of aquatic macrophyte species. Aquat. Bot. 75(1): 71-88. dx.doi.org/10.1016/s0304-3770(02)00166-3
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770, more
Aerial photographs; Aquatic plants; Canopies; Density; Optical classification; Reflectance; Species diversity; Water quality; Finland, Haukuvesi L.; Finland, Onkivesi L. [Marine Regions]; Finland, Puruvesi L. [Marine Regions]; Marine
|Authors|| || Top |
- Valta-Hulkkonen, K.
- Pellikka, P.
- Tanskanen, H.
Digital false colour aerial photographs of four areal samples of three lakes in the Vuoksi drainage basin, Finland, that differ in trophic state and water quality were used to clarify the reflectance characteristics of various life forms and species of aquatic macrophytes at green, red and near-infrared (NIR) wavelengths. The results indicated that the classification of aquatic macrophytes is affected by the density of the vegetation, the openness of the canopies and the amounts, forms and orientations of the leaves. A dense helophyte vegetation differed from nymphaeids in having a higher reflectance in the near-infrared wavelength area than at green or red wavelengths, whereas a sparse helophyte vegetation eventually merged with nymphaeids, and the reflectance properties of the sparsest vegetation of all the life forms did not differ from those of unvegetated water areas. In general, the best classification accuracies (80-91%) were achieved when aquatic macrophytes were categorized according to life forms or phenotype groups and not species. The macrophyte categories differed from one area to another due to variation in species composition and density. In lakes with good Secchi disc transparency, classification was disturbed by reflectance from the lake bottom, while in lakes with a low Secchi disc depth, the substances contained in the water had an effect on the total reflectance.