The effects of the mulch and fertilizer treatments on tree growth corresponded with their
effects on plant available nitrogen. In 1998, the radial trunk growth of river birch was greater in
the composted yard waste mulch treatment (6.9 ± 0.4 mm) than the ground wood (4.7 ± 0.4 mm)
and bare soil treatments (4.5 ± 0.4 mm). In 1999, river birch growth was again greatest in plots
mulched with composted yard waste, and was slowest in the wood pallet treatment (Figure 5).
Fertilization increased the growth of trees mulched with recycled pallets, but had no effect on the
growth of trees mulched with composted yard waste (Figure 5).