The bamboo enigma: the story of a weird grass
How did a suicidal grass outcompete trees and dominate forest canopies? Simple mathematical models put different pieces together into one picture.
Bamboo is known for its rapid expansion in forests and extensive monospecific stands, which prevent tree regeneration and arrest succession, thereby impacting forest structure, carbon dynamics, and biodiversity. However, it remains unclear whether bamboo-dominant forests are transient or stable, partly due to bamboo’s long and mysterious life cycle. Many bamboo species, capable of colonizing forest gaps through vegetative propagation, take more than 60 years to flower, making them challenging to observe or track. These species are usually semelparous, flowering simultaneously and dying afterward, which provides opportunities for bamboo seeds to germinate while facilitating the resurgence of trees. Furthermore, most long-term forest monitoring data often exclude bamboo as a weed or overlook its impact due to the focus on old-growth forests, resulting in limited knowledge about the conditions of forests arrested by bamboo.
We have developed the Arrested Succession Hypothesis to demonstrate how various life history traits and environmental conditions enable bamboo to successfully arrest succession in both tropical and temperate habitats. We hypothesize that this is the only strategy that allows shade-intolerant grasses without secondary growth to exclude trees competitively. This hypothesis offers a parsimonious explanation by consolidating the complex puzzle of bamboo into a coherent framework, where all the pieces fit together seamlessly. The criteria derived from our models enable us to predict whether gaps will remain permanently arrested or if they are reversible under bamboo dominance, based on a set of bamboo life history traits and habitat conditions, including disturbance regimes, light availability, and climatic drivers of productivity. In essence, our study provides the first theoretical explanation of the diverse life history strategies exhibited by bamboo species and their role in arresting succession. Furthermore, our findings identify crucial empirical questions and open up new avenues for future research, enhancing our ability to predict competition outcomes between bamboo and cohabiting species and the long-term ecological effects of bamboo dominance.
This work is published in Ecological Monographs; you can read it here. Meanwhile, if you are a forest ecologist interested in incorporating bamboo into your existing work, or if you are interested in starting to compile a global database of bamboo traits, please get in touch! Together, I hope we can bring more attention to secondary forests dominated by bamboo, lianas, and other non-traditional “weird” species essential to forest structure and function.