4.3. Fertilization
Fertilization is commonly used in intensively managed forest stands. Many forest ecosystems are nitrogen (N) limited, and an increase in N supply can enhance NPP and SOC stock. In the forests of the northeastern US, Magill and Aber (2000) observed that forests are N-limited even though soil microbial populations may be limited by the amount of C required as an energy source. In Maine, USA, Parker et al. (2001) observed that 8 years of applying (NH4)2SO4 as N deposition also significantly reduced forest floor C:N ratios from 30.6 to 23.4. Forest floor C and N stocks were lower in the treated watershed (38 Mg C/ha, 1612 kg N/ha) compared with the reference watershed. Resh et al. (2002) observed greater soil C sequestration (0.11