Chemical properties of foliage and O horizons
The highest concentration of N was measured in the leaves of black
locust (33.7 mg g-1), followed by black alder (28.1 mg
g-1), silver birch (18.6 mg g-1) and
Scots pine (12.1 mg g-1) (Table 2). The leaves of
black alder had the highest P concentration (1492 µg
g-1) significantly higher than in the leaves of birch
(1276 µg g-1) and the Scots pine needles (1009 µg
g-1). The P concentration in the foliage of black
alder (1401 µg g-1) was significantly higher than in
Scots pine needles but not than in the silver birch leaves (Table 2).
The leaves of N-fixing species were characterized by significantly lower
C-to-N and C-to-P ratios but significantly higher N-to-P ratio than the
foliage of non-N-fixing trees. The largest C-to-N and C-to-P ratios and
the smallest N-to-P ratio were determined in the Scots pine needles.
The O horizons under both N-fixing species contained more N than the O
horizons under both non-N-fixing trees (Table 3). However, this was not
the case for P. The highest concentration of P in the O horizons was
determined under silver birch (851 µg g-1) followed by
black locust (808 µg g-1). The P concentration under
alder was significantly lower (747 µg g-1) compared
with birch but higher than under pine (649 µg g-1).
The C-to-N ratio was significantly lower and the N-to-P ratio
significantly higher under N-fixing trees than under both non-N-fixing
species. However, the C-to-P ratio was significantly higher under Scots
pine and black alder than under birch and black locust.