Water retention characteristics of Sphagnum and their relationship with soil nutrient content in the peatland of Maruo,Upland Guizhou

The water retention capacity of Sphagnum plays an important role in the formation of peatlands. Studying the relationship between Sphagnum and soil nutrients is helpful for the protection of peatlands and their restoration following degradation. The biomass, water-holding capacity, and saturated water absorption rate of Sphagnum and soil nutrients in the peatland of Maruo upland were measured and then evaluated by variance, correlation, and redundancy (RDA) analyses. Results showed that there were three Sphagnum species in the peatland, i.e., Sphagnum cuspidatum Ehrh., Sphagnum multifibrosum X. J. Li & M. Zang, and Sphagnum ovatum Hampe. Among these species, Sphagnum cuspidatum Ehrh was dominant, accounting for 87.2% of total Sphagnum coverage. In general, the biomass of Sphagnum was (0.62 ±0.01) kg/m², natural water storage was (9.42 ±0.45) kg/m², and saturated water absorption rate was 1827.41% ±34.56%, thus indicating strong water storage capacity. RDA analysis showed that the biomass, saturated water storage, and saturated water absorption rate of Sphagnum were mainly affected by total potassium (TK), total phosphorus (TP), available potassium (AK), available phosphorus (AP), and available nitrogen (AN) content in the peatland soil. Fresh weight, natural water storage, and natural water absorption of Sphagnum were mainly affected by soil pH and water level. The biomass, saturated water storage, and saturated water absorption rate of Sphagnum were positively correlated with soil TK content and negatively correlated with soil TP, AP, AK, AN, total nitrogen (TN), and soil organic matter (SOM) content. These results indicate that soil TP, AP, AK, AN, TN, and SOM can inhibit the water retention capacity of Sphagnum.