Impact of timber harvesting on carbon storage in montane forests of central Mexico

Abstract

Cut stumps are the legacy of forest harvesting and allow for the estimation of carbon loss from the ecosystem. The objective of this study was to estimate aboveground carbon storage and the impact of forest harvesting based on measurements of cut stumps in pine forests within the Area de Proteccion de Flora y Fauna Nevado de Toluca (APFFNT) in the state of Mexico. A total of 1621 circular 0.1-ha sampling plots were established in a 12,924 ha pine forest (1.25% sampling intensity). Biomass was calculated using conventional volumetric equations incorporating species-specific wood densities. Aboveground carbon storage in the biomass was stratified by forest type including dense forest (≥ 336 trees), semi-dense forest ( 150 trees), fragmented forest ( 20 trees), and stands with isolated trees (< 20 trees). In the 12, 924 ha of forest dominated by Pinus hartwegii, 1,695,004 MgC was contained in aboveground biomass. Data on forest harvesting obtained by analysis of recent cut stumps allowed for the estimation of the removal of 42,701 MgC. In addition, we accounted for carbon in wind thrown trees of 14,904 MgC, some of which were removed over time in harvests. Total loss of carbon from the forest corresponded to 211,218 MgCO2 per year. In the APFFNT, forests dominated by pine with high biomass (P. hartwegii and P. montezumae) are being replaced by those with lower biomass (Alnus jorullensis). Changes in these communities will result in lower carbon capture in the APFFNT.