Spatial Distribution Pattern And Typical Habitat Characteristics Of Sphagnum Bog In Southwestern Hubei Province

Sphagnum is the dominant species of peatland.Its huge carbon storage and carbon sequestration potential make it a key ecosystem for global carbon cycle research.However,the investigation and research on sphagnum bog are mainly concentrated in the cold temperate zone of the Northern Hemisphere,mostly developed in the cold moraine landform area.However,the investigation and research on the subtropical sphagnum bog is relatively late,and its climate,landform and other habitat characteristics are completely different from that of the cold temperate sphagnum bog.Therefore,the investigation and study on the habitat characteristics of subtropical sphagnum bog will help us to understand the sphagnum bog more comprehensively.To this end,we took the sphagnum bog in southwestern Hubei province as the research object.Besides investigating the spatial distribution of sphagnum bog in southwestern Hubei province,we selected typical sphagnum bog to analyze the habitat characteristics.This will enrich the database of subtropical sphagnum bog,provide reference for the protection of the sphagnum bog in southwestern Hubei province,and help the research on the formation mechanism of subtropical sphagnum bog.This study mainly draws the following conclusions:（1）The sphagnum bog in southwestern Hubei province is distributed in the intermountain depression or gully area above 1300 m in six counties and cities such as Enshi,Xuan’en and Wufeng,with a total area of 87.66 hm~2.Among them,the sphagnum bog in Taishanmiao of Enshi has the largest area of 42.91 hm~2.In addition,the mean values of landscape fractal dimension index and landscape separation degree of sphagnum bog in southwestern Hubei province were 1.07 and 0.047,respectively.The shape of wetland was simple and regular,and a few wetlands were seriously disturbed.（2）The distribution of sphagnum bog in southwestern Hubei province has typical characteristics of geology,geomorphology,soil,climate and vegetation.Geology:The distribution area of sphagnum bog in southwestern Hubei province is in the middle Devonian system.The bedrock of the wetland is mainly calcite shale and kaolinite clay rock with strong water-repellent ability.Physiognomy:The slope of sphagnum bog in southwestern Hubei province is within 2.012～4.544°,belonging to the gentle slope,but the slope direction has no obvious influence on the distribution of sphagnum bog.The wetland is mainly distributed in the altitude range of1326.94～1882.19 m,which belongs to the high mountain area of western Hubei and South Asia.The regional fluctuation range is 391.56～939.27 m,which belongs to the type of low mountain and shallow cut and medium cut.Soil:p H of sphagnum bog soil in southwestern Hubei province was 4.12～5.52.Soil bulk density ranged from 0.21～2.40 g·cm^-3.The soil moisture content was 46.98～89.63%.The total carbon content of soil was 7.64～26.37%.The soil soluble organic carbon mass concentration ranged from 24.94～65.48 mg·L^-1.Soil total nitrogen content ranged from 0.37～1.26%.The soil alkali-hydrolyzable n mass ratio ranged from 200.16～582.39 mg·kg^-1.Soil C/N ratio ranged from 15.48 to 20.9.The total phosphorus content in soil ranged from0.37～1.26%.The content of polyphenols in soil ranged from 1.92～4.51μg·m L^-1.In addition,soil bulk density and p H increased with the increase of soil depth.Soil moisture content,total carbon content,total nitrogen content,total phosphorus content,mass concentration of soluble organic carbon,alkali-hydrolyzable nitrogen content and polyphenol content decreased with the increase of soil depth.Climate:The average monthly temperature of sphagnum bog in southwestern Hubei province is between-2.4℃and 24.0℃,the average annual rainfall is 1658.9 mm,and the water level of the wetland fluctuates in the range of-17.2～2.7 cm.Vegetation:There are 143species belonging to 93 genera and 62 families in typical sphagnum bogs in southwestern Hubei province,of which 5 species are common,including sphagnum,Dicranopteris japonica,Aonosmia saponicum and Malus hupeiensis.The biomass of wetland vegetation was 1.31±0.22 kg·m^-2.On the whole,the diversity index of typical sphagnum bogs in southwestern Hubei province was low.（3）Through the correlation analysis of habitat factors,it was found that soil bulk density was negatively correlated with soil total carbon,soil total nitrogen,soil alkali-hydrolyzable nitrogen,and annual rainfall in typical sphagnum bogs in southwestern Hubei province.There was a significant negative correlation between soil moisture content and moss coverage.Soil total carbon was positively correlated with soil total nitrogen,soil alkali-hydrolyzable nitrogen and soil moisture index.There was a significant positive correlation between soil total nitrogen and soil alkali-hydrolyzable nitrogen,and between soil total nitrogen and annual rainfall.There was a significant positive correlation between soil alkali-hydrolyzable nitrogen and annual rainfall.The mean annual temperature was negatively correlated with humidity index and moss coverage.There was a significant positive correlation between moisture index and moss layer biomass.