Xiaogai Ge, from the Research Institute of Subtropical Forestry of the Chinese Academy of Forestry, and Mai-He Li, from the Swiss Federal Institute for Forest, Snow, and Landscape Research in Switzerland, discuss their article: Drought Decreases Carbon Flux but Not Transport Speed of Newly Fixed Carbon from Leaves to Sinks in a Giant Bamboo Forest

Why this matters

Patterns and responses in allocation of photosynthetically-produced carbon is crucial for understanding forest ecosystem carbon dynamics and stocks in a changing world. Bamboo, unlike many trees, always grow as large networks connected by rhizomes, belowground stems. These rhizomes may be vital for the storage and sharing of carbon. However, we still do not have a comprehensive understanding of this process in bamboo forests, particularly in response to future climate change scenarios like drought. This carbon sharing network may enhance the resilience and stability of bamboo forests to environmental stress, potentially influencing ecosystem level carbon sequestration.

Rhizome network and interconnected neighbors of bamboo. Photo by Aiwu Jin.

What we did

In 2019, we conducted a field experiment in subtropical China, using stable carbon isotopes to track the formation of newly photosynthesized carbon in young bamboo plants and its translocation to older neighbors via rhizomes. This experiment was performed under both long-term dry conditions (a five-year drought) and normal conditions. We monitored the labeled carbon signals in leaves, branches, roots, soil, and soil respiration for one year following the labeling.

Our field experiment using ¹³C-labeling with moso bamboo, conducted in subtropical China. Photo by Xiaogai Ge.

What we found

Drought decreased leaf photosynthesis and reduced the allocation of carbon from leaves to other tissues within young plants, as well as to their interconnected neighbors. However, it did not affect the rate of carbon movement either within the young plants, among neighboring plants, or into the soil. Young plants primarily retained the newly assimilated carbon for their own needs, while also sharing smaller quantities with older, interconnected neighbors, regardless of drought exposure.

What it means

In bamboo forests, drought decreases carbon fixation and its allocation, but it does not appear to alter the carbon sharing mechanisms among interconnected neighbors or within the soil. This suggests that interconnected plants may enhance their resilience, resistance, stability, and survival rate in response to stress through resource sharing – a potential advantage for clonal plant populations in the face of further climate change.