Global climate change will alter forests by shifting species ranges, which has implications for their ecological functions. Annual tree-ring widths and wood density are useful proxies for carbon cycle studies across a range of species. Here, using a dendroecological approach we sought to understand the carbon accumulation rates of two representative pine species growing on contrasting wet (P. arizonica) and dry (P. cembroides) sites and reveal how such species cope with climate variability. Although the rate of carbon gain was not significantly different across sites, we found that variations in carbon accumulation responded differently to specific hydroclimate drivers, site conditions, or to functional features of each species, which are still to be explored. Overall, annual carbon accumulation (C) was less sensitive to climate variability than ring width and wood density. Annual C was more sensitive to rainfall in the cold season (P. arizonica) and to the start of spring (both species). Our species-specific approach provided a suitable basis for modeling projections in the long-term carbon balance in these forests. Using species-specific tree-ring data has the potential to yield better estimations given that tree rings reflect fine spatial and temporal resolution, thereby reducing the uncertainty in forest carbon budgets.