BIOMASS STUDIES IN SEMINATURAL ECOSYSTEMS INFLUENCED BY SCYTHING AT THE SOLENDET NATURE-RESERVE, CENTRAL NORWAY .2. WOODED GRASSLAND VEGETATION

This investigation is based on analyses in 1992 and 1993 of the above- and below-ground biomass on permanent plots in a herb- and grass-rich birch woodland community (Lactucion alpinae alliance). The biomass (b oth above- and below-ground) decreases with increasing frequency in sc ything of the plots in a series: not scythed since 1950, scythed bienn ially, scythed annually. The number of individuals increases through t his series. The plant cover also changes, as regards dominant species, from tall herbs (Crepis paludosa, Geranium sylvaticum, Geum rivale) t o grasses (Agrostis capillaris). The differences in the moss layer are very distinct, from the scattered occurrence of bryophytes to a dense cover of Rhytidiadelphus squarrosus/subpinnatus in the intensively-sc ythed plots. Through the series referred to, the above-ground biomass changes from more than 2000 kg/ha to about 1000 kg/ha. The below-groun d biomass changes from 4-5000 kg/ha to about 2000 kg/ha. There are con siderable differences in both the number of shoots and the biomass bet ween the compared years, perhaps partly due to a methodological bias a nd partly because of fluctuations in climatic conditions.