Passive lichen monitoring studied lichen naturally occurrence on free-standing trees in 1991. Species and frequency were evaluated (Linders 1991, SenStadtUm 1993b). The basic grid of the Cadastre of Ecological Pollution Effects was extended by four transsections. This allowed about 12,000 sq. km of the Berlin metropolitan area and surroundings to be representatively processed for data on background pollution levels. Lichen growth on ten trees at each of 64 sampling points was studied for existing species, coverage, frequency, and vitality.
The registration was conducted as a grid-point oriented, standardized vegetation mapping for an “Index of Atmospheric Purity” (cf. De Sloover and Le Blanc 1968). An area-oriented random sample mapping of flora was conducted parallel. A draft for VDI Guideline 3799 Part 1, “Mapping of Lichen for Assessment of the Air Quality” was issued later in August, 1993. A determination of “Air Quality Classes” as defined in the draft was then made.
The foliose lichen Hypogymnia physodes has been exposed in active monitoring procedures at 15 locations in West Berlin since 1981 (Cornelius et al. 1984), and at 48 sites of the basic grid in 1991/92 and/or 1993/94 (Metzger 1992, 1995, SenStadtUm 1993b). The condition of the lichen during the five- and twelve-month exposure periods was photographed monthly, so that the temporal course of damage was documented. Beyond determination of the mortality rate, an evaluative scheme for lichen sorales was used beginning in 1991. The sorale, organs for vegetative reproductive, are a sensitive distinguishing feature for determining pollution influences (cf. Mezger 1992). An analysis of the pollutant sulfur accumulated in this period enabled a spatial differentiation of possible causes of pollution.
Analysis of Pine Needles
One year-old pine needles were taken from 25 – 30 year-old pines (Pinus silvestris) after needle drop (abscission) between the end of October and the beginning of November, 1991. The pines grew in the vicinity of monitoring basic grid intersections at well-aired locations not directly influenced by emissions. Samples were taken at only 47 sites, for no Pinus silvestris pines were found at the sampling point “Mitte”, in the vicinity of Alexanderplatz. Twig samples from all directions of exposure were mixed for determination of contents.
Standardized Rye Grass Cultures
Rye grass was exposed at 15 sampling points in West Berlin during the growing season from May to October, 1981, (Cornelius et al. 1984), and at 48 sampling points from June to September, 1993 (Kuznik 1993). The breeding, culture, and exposure of rye grass followed VDI 3792, although only six exposures were conducted instead of the recommended ten to twelve.
Green Kale Exposure
A 64-km long east-west transect within the basic grid was defined along a theorized pollutant gradient between the inner city and the less-polluted surrounding areas. Selected organic pollutants were investigated in an eight-week exposure of green kale in October/November, 1993, and July/August, 1994 (cf. Map 03.07.4). The sampling points of this transsect were 4 to 8 km apart. The study area had a size of about 260 km2.
The “motor vehicle dimension figure” (TÜV-Umwelt Berlin-Brandenburg 1995) was employed for a determination of the influence of motor vehicles, one of the main sources of PAH. It is based on a mean value of autumn and summer exposure.