Abstract:Clonal morphological plasticity, closely related to the maintenance and regeneration of populations, is the ability for a plant to adapt to a changing environment. In a field experiment, the Hemiview digital canopy analysis system was used to measure the canopy structures (canopy openness, CO; leaf area index, LAI; mean leaf angle, MLA) and light conditions (direct solar radiation under canopy, Dir; diffuse solar radiation under canopy, Dif; Total solar radiation under canopy, Tot) in three typical forest types (deciduous broad-leaved forest, evergreen and deciduous broad-leaved mixed forest, evergreen broad-leaved forest) in Jinfo Mountains National Nature Reserve, Chongqing. The clonal morphological plasticity of understory dwarf bamboo, Fargesia decurvata, was also measured. Moreover, the relationship between canopy structure and morphological plasticity of F. decurvata was discussed. The results showed that:(1) With the development of forest succession, the CO and MLA decreased, but LAI increased, resulting in the increase in light interception capability of forest canopy and the decrease in the light intensity under forest canopy (P < 0.05). (2) Forest canopy condition had a significant effect on the morphological plasticity of F. decurvata ramets. With the decrease in light intensity, the culm height, basal diameter, leaf area, and biomass of F. decurvata ramets decreased. However, decreased light intensity can increase the specific culm length, leaf area ratio, and specific leaf area to improve the utilization efficiency of light and increase the branch angle of spacer and specific spacer length to adapt to low light environments. (3) Under the low light environment in an evergreen broad-leaved forest, F. decurvata reduced its investment in rhizome but allocated more biomass for culm and leaf growth. However, in the deciduous broad-leaved forest, F. decurvata reduced the allocation of branches and leaves and increased the investment in rhizome growth (spacer length and diameter), which can be considered as a foraging behavior to searching much more water resources. These results suggested that the morphological plasticity of F. decurvata underwent significant change in different forest canopies, which is the result of adaptive response to different forest canopy structures and light conditions and enhances the ability to acquire and utilize light resources in heterogeneous light environments. Moreover, the communities may be able to coordinate and control the development of dwarf bamboo by controlling the change of canopy structures and light conditions.