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Báo cáo lâm nghiệp: "Succession of or stand age"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Succession of or stand age? | 758s Ann. Sci. For. 1989 46 suppl. 758s-761s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Succession of mycorrhizae a matter of tree age or stand age D. Blasius and F. Oberwinkler Institut fur Botanik Spezielle Botanik Mykologie University Tubingen Aufder Morgenstelle 1 D-7400 Tubingen F.R.G. Introduction There is a considerable amount of published evidence to support the view that a succession of mycorrhizae occurs during the development of first-rotation forest plantations Dighton and Mason 1985 Dighton et al. 1986 Haas 1979 Ricek 1981 . As a consequence early stage and late stage fungi were distinguished thus reflecting the observations that initial colonizers of tree roots such as Laccaria and Hebeloma species are followed or replaced 6-10 yr after planting by e.g. Lactarius Amanita and Russula species Mason ef al. 1982 Last et al. 1983 . In contrast to the ability to form mycorrhizae under axenic conditions late stage fungi did not infect seedlings in non-sterile soils after afforestation of farmland and in soil cores with fungal inoculum Mason et al. 1983 Deacon eta . 1983 . The physiological status of trees of different ages as well as changes of the substrate and nutrient resources during stand development are considered to be the most relevant factors to explain the temporal and spatial succession phenomena Dighton and Mason 1985 . However tree age and substrate change simultaneously after planting and it is difficult to decide which factor may be more important. Studies in established stands with nearly constant soil conditions and naturally regenerated trees should provide information to answer this question. Materials and Methods Samples of mycorrhizae were taken from 2 stands of Picea abies L. Karst in the Black Forest near Freudenstadt stand and site descriptions have already been given by Blasius eta . 1985 . About 150 1 yr old seedlings and about 100 8-10 yr old trees were removed entirely from the soil and stored at 4 c. Mycorrhizae .