Litter dynamics and fine root production in Schizolobium parahyba var. amazonicum plantations and regrowth forest in Eastern Amazon.

摘要

Forest plantations and agroforestry systems with Schizolobium parahyba var. amazonicum have greatly expanded in the Brazilian Amazon, generally as an alternative for reforesting degraded areas. To our knowledge there are no reports of above- and below-ground production in these forest systems. We quantified litter and fine root production in 6-yr old Schizolobium-based plantation forests (monospecific: MON, mixture: MIX, and agroforestry system: AFS) and in ~25-yr old regrowth forest (REG) over 8-12 months. We used litter traps and ingrowth cores to quantify litter and fine root production, respectively. Annual litter production was significantly lower in Schizolobium-based plantations (mean+or-standard error, MON=5.92+or-0.15, MIX=6.08+or-0.13, AFS=6.63+or-0.13 Mg ha-1 year-1) than in regrowth forest (8.64+or-0.08 Mg ha-1 year-1). Schizolobium-based plantations showed significantly higher litter stock (MON=7.7+or-1.0, MIX=7.4+or-0.1 Mg ha-1) than REG (5.9+or-1.3 Mg ha-1). Total fine root production over an 8-month period was significantly higher in Schizolobium-based plantations (MON=3.8+or-0.2, MIX=3.4+or-0.2, AFS=2.7+or-0.1 Mg ha-1) than in REG (1.1+or-0.03 Mg ha-1). Six-yr old Schizolobium-based plantations and ~25-yr old regrowth forests showed comparable rates of litter+fine root production, suggesting that young forest plantations may be an interesting alternative to restore degraded areas due to early reestablishment of organic matter cycling under the studied conditions.