LARGE-SCALE ESTABLISHMENT OF AMMOPHILA-ARENARIA AND QUANTITATIVE ASSESSMENT BY REMOTE-SENSING

New methods for the establishment of Ammophila arenaria (marram grass), i.e. sowing seeds and disk-harrowing rhizomes, were compared with the traditional method (planting bundles of culms). A large-scale experiment was undertaken on 120 ha of fortified foredune ridge and approximately 40 percent of this area was evaluated by airborne remote sensing (false colour photography). Above-ground biomass production and percentage cover of one- and two-year-old stands were determined by combining field data with colour density measurements on the images. A linear empirical relationship could be established between colour density ratio on the photographs and above-ground biomass, as well as percentage cover. This relationship depended on the age of the plantation. Planting method or relief did not influence this relationship. After the first growing season, planted culms had produced less biomass and percentage cover than stands established via the new methods. In the second growing season the traditional method was the most productive. During the first growing season more than 90 percent of the total area had been stabilized successfully by the new vegetation. Therefore, the alternative methods could be as effective for sand stabilization as the traditional method of planting. Effectiveness of the temporary sand stabilization after sowing and the origin of the culms and rhizomes used for planting affected productivity of the new stands more than the method of establishment. Therefore, if applied properly A. arenaria can be established at a practical level from seeds or rhizomes, instead of from culms. It is also shown that remote sensing could be used to assess above-ground biomass, percentage cover and heterogeneity of foredune vegetation.