Elevated CO2 Moderates the Impact of Climate Change on Future Bamboo

Abstract:

Bamboo is a fast-growing perennial grass that serves as a key economic crop for smallholder farmers, meanwhile, it also has significant ecological value for carbon fixation and water conservation. However, the growth and distribution of bamboo under future climate and elevated atmospheric CO₂ scenarios are poorly understood. In this study, we implemented an ensemble of ten species distribution models, in combination with bamboo distribution data collected from the field and visual interpretation of Google Earth images, to quantify changes in the suitability and the distribution of bamboo habitat by 2100 under two future scenarios (i.e. a moderate RCP4.5 scenario and a pessimistic RCP8.5 scenario) in Madagascar. Our results suggested that climate change reduces the suitability of bamboo habitat by 31% and reduces the areas of potential bamboo habitat by 63.6±3.2% towards 2100 under RCP8.5. However, elevated atmosphere CO₂ concentration offsets the negative impact of climate on bamboo, and enhances its ability to climatic adaption with 111.6±9.8% of newly suitable areas. These new areas, however, will score a lower degree of habitat suitability than current by 27%. We also found that the reduced suitability of suitable areas is related with increases in monthly potential evapotranspiration of the warmest quarter and the minimum temperature of the warmest month, while a decrease in isothermality and increasing precipitation of warmest quarter results in expansion of potential bamboo habitat. Our study suggests that elevated CO₂ mitigates the decrease in habitat suitability and drives an increase in the area of bamboo habitat through enhancing water use and decreasing potential evapotranspiration, highlighting the key role of CO₂ in determining the future distribution of bamboo.