Carbon storage in biomass, litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Abstract

Replantation of degraded forest using rapid-growth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass, forest floor, and soil organic matter. We assessed the potential of 20-year old stands of three rapid-growth tree species, including Alnus subcordata, Populus deltoides and Taxodium distichum, for carbon (C) storage at ecosystem level. In September 2013, 48 replicate plots (16 m × 16 m) in 8 stands of three plantations were established. 36 trees were felled down and fresh biomass of different components was weighed in the field. Biomass equations were fitted using data based on the 36 felled trees. The biomass of understory vegetation and litter were measured by harvesting all the components. The C fraction of understory, litter, and soil were measured. The ecosystem C storage was as follows: A. subcordata (626.5 Mg ha−1) > P. deltoides (542.9 Mg ha−1) > T. distichum (486.8 Mg ha−1) (P < 0.001), of which 78.1–87.4% was in the soil. P. deltoides plantation reached the highest tree biomass (206.6 Mg ha−1), followed by A. subcordata (134.5 Mg ha−1) and T. distichum (123.3 Mg ha−1). The highest soil C was stored in the plantation of A. subcordata (555.5 Mg ha−1). The C storage and sequestration of the plantations after 20 years were considerable (25–30 Mg ha−1 year−1) and broadleaves species had higher potential. Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.