Research On The Effects Of Scenic Environment On GHG Fluxes Patterns Of Zhalong Wetland

As a hotspot for greenhouse gas（GHG）fluxes,wetlands play an important role in global climate change.With the significant increase in human exploitation of wetlands,the ecological balance within natural wetland systems has been greatly disturbed,which in turn has an impact on global climate change.As an important component of natural wetlands,inland saline wetlands are prone to imbalance and frequent flooding,making them more vulnerable to human activities and flooding environments.However,studies on the mechanisms of GHG fluxes from inland saline wetlands in response to anthropogenic disturbance and water level are incomplete,and the factors regulating GHG fluxes from wetlands under scenic environment changes are unclear.In this paper,the most typical inland saline wetland ecosystem in northeastern China,Zhalong Nature Reserve,was used as the research object.The boat dock next to the river subject to cruise and the scenic trail next to the near visitor trail,as well as the dry land in front of the museum,the reed wetland with water level 10-20 cm,and the reed wetland with water level 0-10 cm were selected as experimental sites to monitor Carbon dioxide（CO₂）、methane（CH₄）and nitrous oxide（N₂O）fluxes were monitored to investigate the effects of anthropogenic disturbance and water level on GHG fluxes from the wetlands,to investigate the effects of anthropogenic disturbance and water level on GHG fluxes and the driving mechanism,and to provide a theoretical basis for supplementing GHG fluxes data from inland saline wetlands and understanding the response of inland saline wetlands to the environment.By comparing the differences between the GHG fluxes and environmental factors in the cruise ship pier sample site and the scenic trestle sample site,we found the effects of anthropogenic disturbance on CO₂and CH₄fluxes in the saline wetlands of Zhalong are different.The differences between the cumulative and mean CO₂and N₂O fluxes of the cruise ship pier and scenic trail samples were not significant,and the mean and cumulative CH₄fluxes of the cruise ship pier sample were significantly lower than the mean and cumulative CH₄fluxes of the scenic trail sample.Air temperature,soil temperature,water level,water p H,soil ammonium nitrogen（NH₄⁺-N）content,and soil total organic carbon（TOC）content could explain 57.4～84.5%of the variation in CO₂fluxes.Soil temperature,water table,soil nitrate-nitrogen（NO₃^--N）content,and soil TOC content could explain 31.44 to 83.11%of the variation in CH₄fluxes.The N₂O fluxes of cruise ship wharf sample site increases with TOC and p H of 10-20 cm soil.The N₂O fluxes increases with soil TN content of 0-10 cm.Anthropogenic disturbance had no significant effect on wetland CO₂and N₂O fluxes,but a certain frequency of boat trips would destroy the anaerobic environment of the wetland,which in turn would lead to a decrease in wetland CH₄fluxes.We compared the GHG fluxes and influencing factors at different water level sites to clarify the influence and driving factors of water level on wetland GHG.The significance analysis of the cumulative CO₂fluxes from wetlands at different water levels showed that water level had no significant effect on the cumulative CO₂fluxes from wetlands.Water level,temperature,soil water content,soil NH₄⁺-N content,and TOC content could explain 24.45～98.9%of the variation in GHG fluxes.The average and cumulative CH₄fluxes in the three sites were significantly different,and the excellent anaerobic environment formed by prolonged flooding of the wetland significantly increased the CH₄fluxes,the higher the water level and the longer the water cover time.There is no significant difference in CH₄fluxes in wetlands with lower water levels（below 10 cm water level）compared to drylands.Therefore,maintaining appropriate water levels in wetlands will not affect the contribution of wetland CH₄fluxes to global warming.At water level 0-10 cm sites,0-10 cm soil NO₃^--N content promotes N₂O discharge.Studies have shown a relatively high abundance of methanogenic bacteria-related functional genes in a water level of 10-20 cm.High water level wetland（10-20 cm）is suitable for the growth and reproduction of methane oxidizing bacteria.Candidatus Nitrososphaera gargensis and Nitriliruptor alkaliphilus have high relative abundance in 0-10 cm soil.Lower water level（below 10 cm）is more conducive to the growth and reproduction of N cycle functional flora.