Table 1.
Stand characteristics and surface soil (0–20 cm) properties at the two old-growth forest sites.
Table 2.
Natural 15N abundance and N mass in the major ecosystem pools in the two old growth forest ecosystems.
Figure 1.
Changes in total 15N recovery rates in the subtropical forest ecosystem at DHS (a) and in the boreal forest ecosystem at DXAL (b) in the (15NH4)2SO4 and K15NO3 tracer treatments at one week, one month, four months, and one year (sampled only at DXAL) after the addition of the 15N tracers.
An asterisk(*)means that there is a significant difference in 15N recovery rates between the two tracer treatments (p<0.05).
Table 3.
Nitrogen deposition and retention in the two old growth forest ecosystems during the experimental period.
Figure 2.
Percentage of recovered 15N in different ecosystem N pools in the subtropical forest ecosystem at DHS and in the boreal forest ecosystem at DXAL in the (15NH4)2SO4 and K15NO3 application treatments.
Figure 3.
15N recovery reduction after the spring freezing and thawing melts in the boreal forest ecosystem at DXAL in the (15NH4)2SO4 and K15NO3 application treatments.
An asterisk(*)means that there is a significant difference in the change of 15N recovery rates between the two tracer treatments (p<0.05).