Simulations Of Potential Vegetation Distribution Based On Holdridge Life Zone Model In North-South Transition Zone Of China

Vegetation as an important part of the natural environment for human survival is vital to human survival and social development.The north-south transition zone in china is not only a climate sensitive zone but also an ecological fragile area,where the vegetation ecological environment is extremely easily affected by climate change.Therefore,understanding the distribution change of potential vegetation under the influence of climate change could provide certain scientific basis for the construction of the zonal ecology restoration and ecological resources protection,and predicting the distribution of potential vegetation under future climate scenarios can also contribute to the ecological construction in this region.Based on the monthly mean temperature and precipitation data of 92 meteorological stations in China and DEM(Digital Elevation Model)data during 1970-2016,we simulated and analysed the vegetation changes in inter-decadal time scale and make a projection of the life zone's distribution patterns under four RCPs scenarios in 2070 s based on BCC_CSM1.1 climate model in north-south transition zone of China by using Holdridge Life Zone model.The results showed that:(1)In the past 47 years during 1970-2016,biological temperature fluctuated and increased,with 0.2526°C/10 a amplitude,precipitation presented a weak downward trend,the tendency of annual precipitation change rate was 3.4 mm / 10 a,potential evapotranspiration ratio showed not significant upward trend,with tendency rate of 0.028/10 a.Climate change tended to be a slight warming-drying status.The space distribution of decadal biological temperature,precipitation and potential evapotranspiration ratio calculated by SPSS and ArcGIS software.The biological temperature distribution mainly decreased from the east to the west gradually and gradually reduce from the south to the north,the spatial distribution of precipitation showed that the precipitation gradually decreased from the south to the north and from the coast to the inland.The potential evapotranspiration ratio in the south was lower than in the north,in plain was higher than in mountains,therein Tibetan plateau was a low transpiration rate inhabited areas,and northwestern loess plateau was a high rate of evaporation concentration area.(2)Based on the Holdridge Life Zone model we analysed the interdecadal potential vegetation distribution calculated by ArcGIS and Matlab in the north-south transition zone and find that: In the past 50 years there are 21 life zone vegetation types in the north-south transition zone,and warm temperate dry forest,warm temperate moist forest,cool temperate steppe,cool temperate moist forest and boreal wet forest are the mainly distributed field types in the north-south transition zone.In the change of area of the each zone types,the biggest change were warm temperate dry forest and warm temperate moist forests,compared to the 1980 s and 1970 s,1990s,the new warm temperate moist forest for the most part,was by warm temperate arid forest transformation,which is associated with an increased precipitation in the 1980 s.However,after the 1980 s,the warm temperate moist forest decreased sharply in the latter two decades,and the reduced area was mainly transformed into warm temperate dry forest,subtropical mois forest and subtropical dry forest.The area of subtropical dry forest and subtropical moist forest continued to increase in the 1990 s and 2000 s,which were the main response of vegetation in parts of the north-south transition zone to the warming and drying climate.In terms of the average center of each decadal life zone type calculated using ArcGIS,the subtropical moist forest,warm temperate thorn steppe woodland and cool temperate moist forest migrated much,boreal dry scrub,boreal wet forest and cool temperate desert scrub tilted little,in addition,the average center of all life zone type moved to the north except cool temperate desert scrub,warm temperate thorn steppe woodland and warm temperate moist fores,meanwhile,several life zone types located in the northwest of the north-south transition zone migrated less than that in southeast area,the life zone type in plateau had a smaller migration range than that in mountain and plain.(3)The potential vegetation distribution changes in 2070 s in the north-south transition zone predicted under four RCPs scenarios based on the Holdridge Life Zone model showed that: There are 17 vegetation types in the north-south transition zone in 2070 s,and alpine desert,subalpine dry tundra,subalpine moist tundra,boreal desert and boreal dry scrub these five life zone types disappeared compared with 2010 s,and there are three kinds of life zone vegetation,boreal rainforest,warm temperate desert scrub zone and subtropical thorn steppe woodland came along.The warm temperate dry forest,subtropical moist forests,subtropical arid forests,and cool temperate steppe are the mainly distributed field types in the north-south transition zone in 2070 s.In terms of the area change amplitude of all kinds of life zone types,the higher RCP discharge,the greater range of vegetation distribution pattern change in the north-south transition zone in 2070 s.Moreover,the higher the RCP emission concentration is,the more the warm temperate dry forest,warm temperate moist forest and cool temperate steppe are reduced,and the more the area of subtropical dry forest and subtropical moist forest are increased under the high emission scenario(RCP6.0,RCP8.5),the subtropical forest vegetation area gradually expanded and overpass the warm temperate forest vegetation,which would become the dominant vegetation in the north-south transition zone,therein the newly added subtropical forest vegetation most are transformed from the warm temperate forest due to the increase in temperature.We can infer from the deviation trend of the average center of the life zone type in the 2070 s under the RCPs scenario that: The migration ranges of subtropical dry forest,warm temperate thorn steppe woodland,cool temperate steppe and boreal wet forest are larger than those of other life zone types,and therein the migration range of subtropical dry forest is the largest and that of cool temperate desert shrub is the smallest.The deviation distance increases with the increase of RCP emission concentration.The average center in the 2070 s life zone types are mostly shift northward compared with the 2010 s.