TO WHAT EXTEND DOES THE SULFUR-CONTENT OF FIR NEEDLES REFLECT THE SPATIAL AND TEMPORAL VARIATION OF AIRBORNE SULFUR-DIOXIDE - METHODOLOGICAL PROBLEMS IN ANALYZING BIOMONITORING NETWORKS
T. Fauskessler et al., TO WHAT EXTEND DOES THE SULFUR-CONTENT OF FIR NEEDLES REFLECT THE SPATIAL AND TEMPORAL VARIATION OF AIRBORNE SULFUR-DIOXIDE - METHODOLOGICAL PROBLEMS IN ANALYZING BIOMONITORING NETWORKS, Forstwissenschaftliches Centralblatt, 115(6), 1996, pp. 336-349
Since the late seventies, a biomonitoring network of firs located on a
regular grid with distances 16 km (sometimes 8 km) has been operated
by the Bavarian Environmental Protection Agency (LfU); the sulphur con
tents in specimens of recent needles is measured every year (since 198
9 every second year). Between 1979 and 1993, sulphur levels decreased;
the highest values occurred in the northeast of Bavaria. Spatial auto
correlations of adjacent firs were low. We analysed to what extent thi
s biomonitoring network reflects the contamination of the air with sul
phur compounds by comparing the fir measurements to time series of mon
thly SO2-averages from 13 air monitoring stations. High respectively l
ow SO2-loads corresponded in space and time to high respectively low s
ulphur levels in fir needles. Limitations in exploring quantitative do
se-response-relationships resulted from missing values in the sulphur
measurements and from their considerable small-scale variation. Ir is
not possible to discriminate between different hypotheses concerning t
he time interval during which the sulphur is deposited in the fir need
les, because the corresponding aggregate variables are stochastically
dependent.