Uprooted trees,their distribution and influence in the primeval forest biotope

Summary The paper reports results of a long-term (1964–1974) investigation on permanent study sites in natural forest ecosystems of the Tilio-Carpinetum and the Pino-Quercetum in the Bialowieza Forest. The influence of decaying logs and root craters was investigated. It was found that the main causes of uprooting were the spring and autumn winds. Wind direction and the position of logs lying on the ground are correlated. Picea is most susceptible to uprooting by winds. Almost one half of the trees of this species are alive at the moment of uprooting.By mapping changes in the distribution of uprooted trees on a permanent area in time, a balance of the change over in a 10-year period was determined. It appeared that the decomposition is slower than accumulation. From this, it was concluded that the stand is in a phase of natural thinning. In the study site, compartments were disinguished with various degrees of change in the number of uprooted trees, and the consequences of differentiation and constant transformation of the biotope and biocenosis by the occurrence of uprooted trees and by their decay are described.Nomenclature of species follows Flora Europaea.Contribution to the Symposium of the Working Group for Succession Research on Permanent Plots, held at Yerseke, the Netherlands, October 1975.