In order to enrich the understanding of the growth environment of Sphagnum， explore its possible impact on the formation of erosional karst tiankeng， and find more suitable growth conditions for it， we used gradient method， with S.palustre of different canopy density environments in the edge of the Tuntianjing sinkhole in Bijie City， to definite the chlorophyll fluorescence parameters and water storage capacity. Results showed： ①The initial fluorescence（Fo） and maximum fluorescence（Fm） of S.palustre increased significantly with increasing canopy density（Fo：224.67-264； Fm：716-785.33）. The maximum photochemical efficiency（Fv/Fm） of PSⅡ decreased firstly and then became constant； photochemical quenching coefficient（qP） and photosynthetic electron transport rate（ETR） increased significantly（qP：0.17 -0.46； ETR：5.72-9.68） with increasing canopy density； non-photochemical quenching coefficient（NPQ） decreased significantly from 1.57-0.8. ②With canopy density increased， the rate of water absorption and water storage capacity of S.palustre were significantly increased， the natural water absorption and the saturated water absorption increased from 14.36-26.37 and from 21.7-27.01， respectively； the natural water storage increased from 3 032.97-12 816.01， and the saturated water storage increased from 4 576.34-13 175.97. ③Although S.palustre has a good sunproof， they are more suitable for living in the low light conditions. As canopy density increased， it was beneficial to accumulate chlorophyll， promote photosynthesis and increase the accumulation of biomass， leading to a stronger water storage capacity. Competition can inhibit the growth of S.palustre， share soil moisture， and a certain moisture was very important for the growth of S.palustre. ④The good water-holding properties and water absorption of S.palustre have an important role in slowing surface runoff that slowing down in geological processes. The difference in water holding capacity of S.palustre under different canopy densities can affect the distribution of water flow to a certain extent， thus affecting the formation of erosion-type sinkholes.
%U https://bbr.nefu.edu.cn/EN/10.7525/j.issn.1673-5102.2021.02.014