Combining Stand Diameter Distribution Quantified by the Weibull Function to Develop a Carbon Yield Model for Makino Bamboo (Phyllostachys makinoi Hayata)

Bamboo forests with high potential carbon storage have been found worldwide. Makino bamboo is critical, with a broad area of plantations distributed around Taiwan. This study established a thinning trial to monitor aboveground carbon storage (AGCS) and aimed to develop a carbon yield model for this bamboo species based on the Weibull function. Four thinning treatments, each replicated four times, were applied in this study. We collected data in 2019 after thinning and in 2021. We used the allometric function to predict the AGCS and the Weibull function to quantify the diameter distribution for each record. The culm number (N) and the parameters of the Weibull function were employed as independent variables to develop the AGCS model. The results showed that using N as a variable had an 83.6% predictive capability (Radj2 = 0.836). When adding the parameters b and c of the Weibull function to the model, the predictive capability can improve to 93.9% (Radj2 = 0.939). This confirmed that adding the parameters of the Weibull function helped promote AGCS prediction for Makino bamboo. Moreover, the advantages of this model are that it not only shows AGCS but also displays the diameter distribution.