Study On Hydrological Regulation Ability Of Typical Forest Ecosystem In Changbai Mountain

Hydrological regulation is an important function of forest ecosystem.Community composition,vegetation succession and soil properties will affect the hydrological regulation ability of forest.Changbai Mountain is the highest mountain system on the eastern edge of Eurasia,and it’s also strong impact of global climate change.Due to the change of climate and global precipitation pattern,the forest hydrological process and the plant water pattern has changed,resulting in the intensification of intraspecific and interspecific competition and the reduction of forest ecosystem stability.Therefore,it is very necessary to explore the plant water use strategy and forest hydrological regulation ability in climate change sensitive areas.This study takes two typical forest types（primary forest and secondary forest）in Changbai Mountain as the research object.Based on the field measured data,using hydrogen and oxygen stable isotope tracing technology and Bayesian mixed model,this paper expounds the water vapor source and water body of atmospheric precipitation in Changbai Mountain areaδD(δ¹⁸O)isotopes,water use strategies of dominant plants and hydrological regulation ability of forest ecosystem.The results show that:（1）The atmospheric precipitation in Changbai Mountain area is dominated by the inland in winter and the ocean in growing season.In winter precipitationδD(δ¹⁸O)value is low,and the water vapor is mainly from the inland Mongolian Plateau and Siberia.Precipitation in growing seasonδD(δ¹⁸O)value is high,and the water vapor source is mainly the Western Pacific.The study area has significant temperature effect and no precipitation effect.（2）The water conservation capacity of primitive forest is stronger than secondary forest.Due to the heterogeneity of soil,the main movement mode of soil water in primary forest is piston flow,and the main movement mode of soil water in secondary forest is dominant flow.The secondary forest has low canopy density,weak rainfall interception capacity of canopy layer,rapid water infiltration into soil and poor soil water holding capacity,resulting in its water conservation capacity is weaker than that of the original forest.（3）The primary forest plants form a stable water use niche,and the secondary forest is in the stage of vegetation succession.After different rainfall events,Korean pine and Acer Acer mainly use shallow soil water in the original forest,ash and Tilia amurensis tend to use the soil"new"water formed by atmospheric precipitation,and Mongolian oak can adjust its water use strategy according to different precipitation patterns.The main tree species of secondary forest use water in similar soil layers,and the water use mode of plants is almost not affected by precipitation intensity and soil water transport mode.Plants tend to use the"old"water in soil bound water,and there is water use competition among tree species.（4）The regulation function of primitive forest to hydrological process is better than that of secondary forest.When the precipitation is small,the original forest litter and canopy can intercept more precipitation.At this time,plant characteristics play a major role in hydrological regulation.When the precipitation is large,the soil characteristics play a major regulatory role.The secondary forest is consistent with the hypothesis of"two water worlds",while the primary forest is more consistent with the hypothesis of one reservoir.For different precipitation events,the soil and vegetation structure of the original forest has better water storage function and hydrological regulation ability,and has stronger and more lasting water conservation function.To sum up,the ability of primitive forest to retain,regulate and conserve precipitation is stronger than that of secondary forest,which is of great significance to the water conservation function and hydrological regulation of Changbai Mountain.The results will provide the theoretical support and reference for global climate change,ensuring watershed ecological security,rational management and restoration of forest ecosystem in water source area.