Habitat prediction of Sphagnum spp. in the Changbai Mountains based on MaxEnt model

Peatlands are among the most important carbon sinks on Earth and play vital roles in carbon sequestration, hydrological regulation, habitat maintenance, and climate change mitigation. Sphagnum spp. are key ecosystem engineers in wetland ecosystems and dominant peat-forming species in peatlands, with high ecological significance and strong environmental indicator value. To clarify the spatiotemporal distribution patterns of Sphagnum spp. in the Changbai Mountains and to reveal the trends in suitable habitat under future climate change, this study used 1 434 occurrence records and 14 environmental variables to simulate the suitable habitat distribution of Sphagnum spp. using the Maximum Entropy Model (MaxEnt). The simulations were conducted for the baseline period (1981—2010) and for two future periods (2041—2070 and 2071—2100 under three Shared Socioeconomic Pathway scenarios, namely SSP1-2.6, SSP3-7.0, and SSP5-8.5. In addition, the relative contributions of key environmental factors and the characteristics of their response curves were quantitatively analyzed. The results showed that the MaxEnt model performed well, with the Area Under the Receiver Operating Characteristic Curve (AUC) exceeding 0.85 for all simulations across the three periods and three scenarios, indicating good predictive accuracy. Under baseline climatic conditions, the suitable habitat area of Sphagnum spp. in the Changbai Mountains was estimated at 52 800 km², accounting for 20.87% of the total area of the study region, with an elevational range of 200-1 900 m. Under future climate scenarios, the suitable habitat area for Sphagnum spp. showed different patterns of change. Specifically, under SSP1-2.6, the area remained relatively stable; under SSP3-7.0, it showed a declining trend; and under SSP5-8.5, it first decreased and then increased. The main environmental factors affecting the distribution of Sphagnum spp. were topographic factors, particularly elevation and topographic wetness index, as well as climatic factors, including the mean daily maximum temperature of the warmest month, precipitation seasonality, and mean monthly precipitation of the warmest quarter. These results indicate that elevation, potential soil water availability, and temperature together determine the basic spatial pattern of suitable habitat for Sphagnum spp. Future projections further suggest that the potential suitable habitat of Sphagnum spp. will shift toward higher elevations under climate change. This study improves the understanding of the distribution characteristics of Sphagnum spp. in the Changbai Mountains and reveals the potential effects of future climate change on their suitable habitat. The findings provide a scientific basis for the conservation of Sphagnum spp. and peatland ecosystems.