Aboveground carbon stock evaluation with different restoration approaches using tree ring chronosequences in Southwest China

Forest carbon stock evaluation requires estimation of tree growth rates. Traditionally, growth trends in forests are derived either from repeated forest inventories based on permanent sample plots or from space-for-time substitution. Here, past carbon storage trends were estimated using dendroecological methods for different restoration approaches in the subalpine region of Southwest China. Tree ring width chronologies, carbon stock and carbon uptake trends were developed for spruce plantation forest (SPF), natural birch forest (NBF) and natural coniferous–broadleaved mixed forest (NMF). Our findings revealed that average ring width of stands was 3.07 mm for SPF; 1.77 mm for NBF; 2.02 mm for NMF. Carbon stock and uptake rates (mean C uptake every 5 years) for NMF were higher than those in either NBF or SPF throughout the chronosequence. SPF had the lowest carbon storage in the first 25 years and intermediate value in the later years. In addition, carbon stock uptake rate in NMF showed an increasing trend throughout the observation period, while that of NBF and SPF tended to be flat in the last interval. As one of the natural restoration types, NMF had the largest potential to increase carbon sequestration compared with NBF and SPF under the climatic conditions in this region. Management practices should be carried out to promote succession from NBF and SPF to NMF, so as to enhance carbon sinks in the forests of Southwest China.

► Carbon storage dynamics were assessed using dendroecological methods for different restoration approaches.
► Restoration approaches influence growth and carbon storage of forest.
► Higher carbon stock and uptake rate were observed in natural mixed forest.
► Artificial regeneration had the lowest carbon storage in earlier successional stages.
► Natural mixed forest had the largest potential to increase carbon sequestration.