Models to estimate the above and below ground carbon stocks from a subtropical scrub forest of Pakistan

Abstract Despite an increased number of studies on carbon stock estimates from tropical and temperate forests, little information is available for subtropical forests, although they constitute a significant proportion of global forest cover. In this present study, we aimed to assess the above- and below ground biomass allocation strategies and carbon stocks of Acacia modesta and Olea ferruginea, which co-dominate a subtropical dry forest in Pakistan covering approximately 1.6 Mha. This scrub forest has been subjected to mining, overgrazing, and other anthropogenic activities resulting in the loss of trees and habitat degradation. For the assessment of biomass and carbon stock, 11 trees of each species representing the diameter range of 10-52 cm at 1.3 m height were harvested. The harvested A. modesta and O. ferruginea trees showed 80% and 82% of biomass in the above-ground parts and 20% and 18% to below ground parts respectively. We developed power models from the destructive harvest data for both the above- and below-ground biomass components to assess the tree-level carbon. Furthermore, we also estimated the carbon content in the leaves, roots, and shoots of both species by using a carbon analyzer, which ranged from 43.42 - 46.50%. Using the developed models, we found that the total carbon stock was 49.82 t ha-1 in the studied forest with a basal area of 27 m2 ha-1, consisting of 568 trees ha-1. This study provides useful information about the tissue carbon content, on-site models for estimating the above- and below ground biomass and carbon stock in two dominant species from a subtropical dry forest, which can be applied to estimate the carbon stock of forests in arid climate.