Abstract:

Objective: To quantify the potential uncertainty of carbon sequestration estimation caused by the neglect of important factors such as site quantity and stand characteristics in previous studies, the present study proposes a simple and effective method for estimating carbon sequestration potential at the management unit scale that is inspired from the theory of forest resource valuation, aiming to provide some insights on the temporal-spatial configuration of various forest management prescription at the management unit scale under the multifunctional forest management concept. Method: Based on the forest resource survey data of Mao’ershan Experimental Forest Farm in 2022, an adjustment coefficient (K) for stand comprehensive condition was constructed based on the site quality, mean diameter at breast height (DBH) and stand density at the sub-compartment scale using a continuous multiplication strategy. The carbon sequestration potential at the management unit scale was accurately estimated by combining the proposed index K with stand growth process tables for various forest types, as well as the datasets of biomass expansion factors and carbon content of different organs for each forest type. Result: 1) The mean DBH adjustment coefficient ($ {k}_{1} $), stand density ($ {k}_{2} $), site quality adjustment coefficient ($ {k}_{3} $) and total adjustment coefficient (K) in the study area were 1.34±0.52, 0.90±0.45, 0.91±0.45 and 0.89±0.48, respectively. Meanwhile, forest types had significant impacts on the adjustment coefficients (P<0.01), with natural coniferous mixed forests having the greatest K values (1.40), and Pinus koraiensis plantation having the smallest (0.51). 2) The determination coefficient between the estimated unit area volume of the adjusted forest stands and the actual survey values significantly increased by 1.23 times on average (from 0.284 to 0.634) compared with that between the estimated unit area volume of the non-adjusted forest stands and the actual survey values, among which Populus davidiana plantation had the largest increase (10.11 times), while the natural P. davidiana-B. platyphylla forest had the smallest increase (83%). 3) During 2022—2050, the average carbon sequestration of arbor forests in the region was 0.38 t·hm^?2a^?1, and gradually decreased with forest age. Among them, the carbon sequestration rates of natural mixed coniferous forest, natural mixed coniferous-broadleaved forest and L. olgensis plantation were relatively high (>1.00 t·hm^?2a^?1), and those of natural soft-hard broadleaf forest and Pinus koraiensis plantation were relatively lower (< 0.30 t·hm^?2a^?1). Conclusion: The adjustment coefficient for stand comprehensive condition proposed in this paper, namely combining the proposed adjustment coefficient, forest resource planning data and the stand growth process tables together, can accurately estimate the carbon sequestration potential at the management unit scale.

Key words: carbon sequestration potential, forest resources survey data, management unit, stand growth process table, adjustment coefficient