Impacts Of Climate Change And Land Use On The Potential Suitable Distribution Areas Of Crocodile Lizards

Climate change and associated impacts are a major and common cause of the emergence of new species assemblages,species range shifts,localised extinctions,reduced biodiversity,loss of ecosystem resilience and unobserved disturbance mechanisms.The crocodile lizard(Shinisaurus crocodilurus)belongs to the genus Shinisaurus in the family Shinisautidae and is a Class I protected wildlife in China,listed as "endangered" on the IUCN Red List.Crocodile lizards are currently reported to be distributed in some protected areas in Guangdong,Guangxi and Vietnam,with narrow habitat areas and sparse populations.In this study,Max Ent and Mig Clim models were used to reconstruct the distribution of the crocodile lizards during the Last Glacial Maximum(LGM),and to predict the potential suitable distribution area of the crocodile lizards under future climate change scenarios.Based on this,we analyzed and identified key environmental factors affecting the distribution of this species.At the same time,the In VEST model and the land use transfer matrix were combined to analyze the habitat quality in the crocodile lizards range from 1995 to 2020.Finally,based on Zonation model,we proposed the priority conservation areas for crocodile lizards.The main results are as follows:(1)The model accuracy was verified by the receiver operating characteristic curve(ROC),and the area under curve(AUC=0.972)value was greater than 0.9,indicating that the model has a good prediction effect and Max Ent model was feasible for species prediction.(2)Key environmental factors influencing the distribution of crocodile lizards included wettest monthly precipitation(Bio13,37.1%),coldest monthly precipitation(Bio19,17.9%),standard deviation of seasonal variation in temperature(Bio4,14.3%),driest quarterly precipitation(Bio17,10.7%)and annual range of temperature variation(Bio7,10.5%),which contributed to species reached 90.5%.Among the environmental factors affecting the distribution of crocodile lizards,the influence of precipitation factors played a greater role than than the influence of temperature factors.(3)Max Ent model simulations showed that crocodile lizards have a stable distribution area since the LGM,mainly including Shaoguan City in Guangdong Province,Vietnam,Quang Ninh Province and Be Giang Province.Under the current climate scenario,the potentially suitable range of the crocodile lizard was mainly located in Hezhou,Laibin,Guigang and Hechi in northern Guangxi,Shaoguan,Qingyuan,Heyuan and Zhaoqing in Guangdong and the central part of Quang Ninh Province in Vietnam.The potentially suitable distribution areas within Guangxi showed expansion areas.Projections for different climate scenarios,for different time periods,showed that with increasing radiative forcing(SSP1-2.6,SSP2-4.5,SSP3-7.0,SSP5-8.5),the existing habitat of the crocodile lizard was expected to be significantly reduced from 2021 to 2100.The future distribution center of crocodile lizards generally remained in the bordering areas of Guangxi,Guangdong and Hunan.(4)Mig Clim model showed that in the unlimited dispersal scenario,the suitable habitat for crocodile lizards increased and then decreased as the effective radiative forcing increased.In the no-dispersal and limited dispersal scenarios,the suitable habitat for the crocodile lizards declined sharply,even to zero with increasing effective radiative forcing.(5)The land use transfer matrix showed that the dominant landscape types in the study area were arable and woodland,and that the study area has experienced rapid economic development and increasing urbanisation over the last 25 years.The In VEST model showed that low quality habitats were widely distributed,mainly in the periphery of the crocodile lizard’s range.High quality habitats were concentrated in the mountainous forest areas in the central and eastern parts of the study area.Habitat quality remained good in most of the crocodile lizard’s range,with the worst habitat quality and severe habitat degradation in Dateng Gorge.This may be related to the expanding range of human activities,where the human footprint has gradually expanded into the remaining suitable habitat for crocodile lizards,with serious impacts on their habitat integrity and habitat quality.(6)The Zonation model indicated that the priority conservation areas for the crocodile lizard under the climate change scenario were mainly distributed in Guangxi and Guangdong regions of China and northern Vietnam.The existing suitable habitats for the crocodile lizard were protected in the established nature reserves.Under the future climate change scenario,the existing nature reserves for crocodile lizards were still applicable to the future climate change scenario.In conclusion,climate change and anthropogenic activities jointly affect the distribution pattern and habitat quality of the crocodile lizards.The current range of the crocodile lizards is narrow and may shrink further in the future.In order to protect the suitable distribution area of the crocodile lizards and maintain the habitat quality in the range,more conservation measures and population dynamics should be developed in the future.