2.1 Study area
The study area is in the Niangniangshan National Wetland Park Conservation area in China. The wetland is located at the junction of Yunnan-Guizhou Province with geographical coordinates of 104°45 ’24 ”E-104°51’ 41” E and 26°04 ’25 ”N-26°8’ 24” N. It is a typical subtropical karst mountain moss peatlands wetland in the Yunnan-Guizhou Plateau. Moss peatlands are developed in the waterlogged areas of basalt formations on subalpine platforms and have important functions such as water conservation, biodiversity protection, climate regulation and carbon sink. Before the 1990s, a large area of moss peatlands was distributed in the wetland, and different topographic environments formed different moss peatlands, including ombrotrophic PB in the plateau area and minerotrophic SF in the low-lying area. However, in the late 1990s, large-scale drainage and construction of theCryptomeria fortuneana forest resulted in the disappearance of a large area of moss peatlands. The vegetation was mainly swamp forest, and the moss peatlands and herbaceous peatlands were mosaic landscapes. The ecological function of wetlands declined significantly, and the diversity and heterogeneity of vegetation and the environment decreased.
The climate of the area where the wetland is located is cool and humid, which is a typical subtropical monsoon climate. The extreme maximum temperature is 36.7 °C, the extreme minimum temperature is -7.9 °C, and the annual average temperature is 15.2 °C. The average annual sunshine duration is 1615 h, and the percentage of sunshine is 37%. The average annual rainfall is 1413.6 mm, and the average evaporation is 1526.7 mm. The annual average relative humidity is 76%, the maximum relative humidity is 100%, and the minimum relative humidity is 2%. The annual average frost-free period is 271 days. The main soil types in the wetland conservation area are peat soil and scrub meadow soil.