Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Changes of partitioning and increased root lengths of spruce and beech exposed to ambient pollution concentrations in southern England. | 573s Ann. Sci. For. 1989 46 suppl. 573s-576s Forest Tree Physiology E. Dreyer etal. eds. Elsevier INRA Changes of partitioning and increased root lengths of spruce and beech exposed to ambient pollution concentrations in southern England G. Taylor1 . Dobson2 and . Freer-Smith2 1 Division of Biology University of Lancaster Lancaster LA 14 YQ and 2 Forestry Commission Alice Holt Lodge Farnham Surrey GU10 4 LH . Introduction Much circumstantial evidence exists to suggest that drought may act as an inciting factor accelerating the decline of forest trees exposed to chronic doses of air pollution. For instance many reports suggest that major increases in the decline of spruce occurred after hot and dry summers in Germany. Similarly Ling and Ashmore 1987 suggested that for beech loss of green leaves production of small leaves and altered patterns of shoot growth were amongst the symptoms associated with the decline of this species. Experimental work on trees in controlled environments has shown that exposure to gaseous pollution may increase susceptibility to drought in at least 2 ways. Firstly stomatai behaviour may be altered causing both decreases and increases in water loss Mansfield and Freer-Smith 1984 and secondly partitioning between roots and shoots may be altered such that the allocation of biomass to roots is restricted . TERG 1988 . Extrapolation of such results to the field in particular to large trees is unwise since the concentrations used in such experiments are generally in excess of those experienced presently in rural Britain and the fumigations are often conducted over extremely short time periods on a limited number of small trees. In addition little research in Britain has focussed on drought and o3 which are known to occur together during summer months particularly in southern England. The Forestry Commission has recently developed 3 rural sites each with 16 open top chambers to study the effects of ambient concentrations of pollution .
