Water vapor flux characteristics and their relationship with environmental factors in the subalpine peat wetlands of Dajiuhu, Shennongjia

Using the eddy covariance technique, we collected interannual data on wetland water vapor flux and conducted data analysis to study the characteristics of water vapor flux and its relationship with environmental factors in the subalpine peat wetlands of Dajiuhu, Shennongjia. Results showed that:(1) Evapotranspiration accounted for 58.59% of precipitation, indicating that precipitation could meet the needs of water vapor circulation in Dajiuhu. (2) Annual diurnal variation of water vapor flux was mostly positive (release of water vapor), indicating that the peat ecosystem of Dajiuhu was the main source of water vapor. Seasonally, maximum diurnal variation appeared in summer, with the largest change range. (3) Average net radiation varied largely over the year and the maximum appeared in summer, accounting for 34.96% of total radiation over the whole year. There was a high correlation between water vapor flux and net radiation in every season. Correlation coefficients (R²) in spring and summer were greater than 0.7, with the maximum of 0.8347 appearing in summer, better than any other survey region at similar latitude. (4) There was a significant positive correlation between water vapor flux and air temperature each month, except January 2018, with the highest correlation in summer. This was mostly because both plant transpiration and surface evaporation were highly active in summer. (5) Air temperature and net radiation had significant effects on water vapor flux in every season, but correlation varied from season to season. These results showed that net radiation played a more important role in the water vapor cycle than air temperature in the subalpine peat wetlands of Dajiuhu, Shennongjia.