Soil respiration and net ecosystem production in relation to intensive management in Moso bamboo forests

Abstract

Moso bamboo forests represent an important forest type commonly found throughout subtropical China and are characterized by fast growing forests, and involves intensive management, such as reclamation, fertilization, and understory removal. However, effects of intensive management on soil respiration (RS) and net ecosystem production (NEP) remain unclear. In this study, RS was partitioned into root respiration (RR), litter respiration (RL), and soil organic matter derived respiration (RM) by litter removal and trenching approaches. One-year measurements of respiration rates, soil temperature, and soil moisture were conducted in an unmanaged and an intensively managed stand. Regardless of stand management, RS and source components increased exponentially with soil temperature and linearly with soil moisture. Temperature sensitivity (Q10) ranged from 1.6 to 2.5, with the highest value for RM, highlighting the importance of RM in regulating the response of RS to soil temperature change. Annual RS, RR, RL, and RM were 32.6, 10.7, 6.9, and 15.0t CO2 ha−1 a−1 for unmanaged stand, compared to 38.6, 12.5, 7.1, and 18.9t CO2 ha−1 a−1 for intensive managed stand, respectively, indicating that intensive management increased RS by RR and RM. Intensive management also increased NEP with 17.2t CO2 ha−1 a−1 for unmanaged stand and 20.4t CO2 ha−1 a−1 for intensive managed stand. This increase was mainly attributed to the increase in net primary production of bamboo forests under intensive management. However, the sustainability of intensive management needs further investigation due to the reduction of soil organic carbon content after intensive management. Forest management associated with the reduction in soil CO2 flux and increase in stand production should be developed for Moso bamboo forests.