This study aims at comparing the carbon storage ability of Monastery bamboo (Thyrsostachys siamensis Gamble) and Pai Liang (Dendrocalamus membranaceus × Thyrsostachys siamensis) in terms of the different physiological responses to the microclimate. The stomatal conductance, leaf-to-air vapor pressure deficit (LAVPD), chlorophyll content, and water use efficiency (WUE) were measured. Pai Liang had a greater dry biomass per culm than Monastery bamboo, resulting in more carbon storage. Monastery bamboo kept opening its stomata even when LAVPD increased, resulting in the loss of more water and a lower WUE leading to a lower rate of growth and carbon storage. Pai Liang contained higher amount of carbon and nitrogen in the leaf tissue, indicating a better WUE. With regards to the climate change, Pai Liang is recommended owing to a greater carbon fixation and more rapid growth rate compared to the Monastery bamboo.