ESTABLISHMENT AND SURVIVAL OF THREE INVASIVE TAXA OF THE GENUS REYNOUTRIA (POLYGONACEAE)IN MESIC MOWN MEADOWS: A FIELD EXPERIMENTAL STUDY

Abstract: The effect of traditional management on the initial phase of invasion into mesic mown meadows was studied in the Kfivokl~tsko protected landscape area in Central Bohemia, the Czech Republic. In 1996, rhizome fragments of alien species native to Asia, i. e. Reynoutria japonica, R. sachalinensis and their hybrid R. xboheraica were planted in experimental plots and their establishment recorded. Established plants were then subjected to the following six treatments which simulated the management practices traditionally used in the study area: mowing twice a year, grazing bygoats and sheep separately at wodifferent intensities, and a control plot. Plant survival was recorded in the two years following planting. In order to compare the effect of the growing period, the xperiment with R. japonica was conducted in two subsequent years (1995 and 1996) thus allowing observations ver three years on this species. The experiment was carried out in two sites (meadows), with t ree blocks of treatments e tablished in each. Significantly better establishment was found in R. japonica and R. xbohemica than in R. sachalinensis. Survival of all three taxa was negatively effected by all the management treatments applied (P < 0.001). In control plots with plants of all three taxa, there was virtually no mortality during the growing seasons of either year and the number of surviving plants decreased only in the winter. In the former two species, 38.5 + 19.4 % of plants urvived the first winter, the corresponding figure for the latter being only 7.2 ± 6.1%. It can be concluded that traditional management provided it i