SECTION 3 - CHANGES IN FORESTS ON THE CLIMATIC AND AIR-POLLUTION GRADIENTS IN POLAND - TRANSECT STUDIES OF PINE FORESTS ALONG PARALLEL 52-DEGREES-N, 12-32-DEGREES-E AND ALONG A POLLUTION GRADIENT IN CENTRAL-EUROPE - GENERAL ASSUMPTIONS, CLIMATIC CONDITIONS AND POLLUTION DEPOSITION

This research program describes the response of pine forest to changin g climate and environmental chemistry. All 25 selected pine forest sta nds belong to the Dicrano-Pinion alliance and include two associations of pine forest: subcontinental pine forest Peucedano-Pinetum and sub- oceanic pine forest Leucobryo-Pinetum, as well as mixed forest of the Querco-Pinetum type. This program consists of two transects following pollution and continentality gradients across Poland: one from rite we stern border to the eastern border (in the ar ea of Bialowieza Nationa l Park) along the 52nd parallel, and the second from industrial Upper Silesia (SW Poland) to the same point in the Bialowieza area. We assum ed that the first west-to-east transect of sites followed a gradient o f cooling and continentality. The western-eastern site difference in m ean annual temperature averages is 1.8 degrees C (from 8.5 to 6.7 degr ees C); average differences between July and January for most western sites are 18.8 degrees C and for the eastern sire is 22.3 degrees C. E xtension of the continental transect to the west (Germany) and the eas t (Belarus) became possible two years after the program had been initi ated. This so-called 'large transect' spans 20 degrees (from 12 degree s 25' to 32 degrees 60' E) of latitude, with a difference in mean annu al temperature of 3.5 degrees C (from 5 to 8.5 degrees). The second tr ansect was established along a decreasing pollution gradient of sulphu r deposition. The content of sulphur in Scots pine needles varied betw een 0.17% dry mass in Upper Silesa to 0.12% in Bialowieza National Par k. In each forest stand climatic elements (temperature and precipitati on) , the late of radial growth of pine trees, diversify of plant spec ies and forms, some measures of biomass, organic matter turnover measu red by litter fall and decomposition, and diversity of selected groups of epigeic and soil fauna (invertebrates) were measured. Detailed des criptions of important measurements will be presented in two subsequen t papers included in this volume. (C) 1997 Elsevier Science Ltd. All r ights reserved.