Font Size: a A A

Study On The Change Of Suitable Area Of Rare And Endangered Picea Plants In Qinba Mountain Under The Background Of Global Climate Change

Posted on:2024-06-26Degree:MasterType:Thesis
Country:ChinaCandidate:Z W FuFull Text:PDF
GTID:2530307145953279Subject:Geography
Abstract/Summary:PDF Full Text Request
Picea neoveitchii and Picea brachytyla are plants of the same family and genus,both of which are rare and endangered species endemic to the Qinba Mountain.Picea neoveitchii is a national grade II protected plant,which is classified as near-risk grade in IUCN.Picea brachytyla is a national III level protected plant.At present,there are few studies on the distribution of simulated suitable areas and species migration of the above species.In the future,with the deepening of global warming,it will inevitably affect its geographical distribution pattern.Therefore,the purpose of this article is to study the suitable areas of typical rare and endangered spruce plants in the Qinba Mountains,and to explore the effects of environmental factors and future climate change on the suitable areas of species.It provides research ideas and methods for the simulation study of the suitable areas of rare and endangered plants,and provides certain theoretical data support for the subsequent research and protection of spruce species and the ecological construction of the Qinba Mountain.In this article,Picea neoveitchii and Picea brachytyla are taken as the research objects,the effective point data are screened and extracted,and the environmental variables related to their distribution are selected,which mainly include 19 bioclimatic factors,3 topographic factors and 14 soil factors.The environmental variables with absolute value of correlation≄0.8 and large value were screened by SPSS bivariate analysis and Pearson autocorrelation analysis.Based on the operation results of Maxent model,the dominant environmental factors affecting the distribution of species suitable areas were determined,and their influence degree and climatic niche were analyzed.Based on the operation results of Maxent model,the dominant environmental factors affecting the distribution of species suitable areas were determined,and their influence degree and climate niche were analyzed.The maximum test sensitivity plus specificity logistic threshold attributes of the two species were combined to determine the classification of suitable areas and the geographical distribution characteristics of each grade of suitable areas.Based on eight scenarios of 2050s-RCP2.6,2050s-RCP4.5,2050s-RCP6.0,2050s-RCP8.5,2070s-RCP2.6,2070s-RCP4.5,2070s-RCP6.0,2070s-RCP8.5 under future climate model,the change trend of suitable areas of Picea neoveitchii and Picea brachytyla at different levels was simulated and predicted.At the same time,with the help of Arc GIS spatial analysis tool,the distribution site and migration trend of the centroid of the suitable area of the species were calculated,and the control variables were compared and analyzed to describe the change of the suitable area.In this regard,the relevant conclusions of this article are as follows:(1)The Jackknife cutting method and the cumulative contribution rate showed that the main environmental factors affecting the distribution of the suitable area of Picea neoveitchii in the Qinba Mountain were:lower sediment content,lower gravel volume,upper gravel volume,average temperature in the coldest season,and is othermality.Among them,the contribution rate of the three environmental factors of lower sand content,lower gravel volume and upper gravel volume to all environmental factors was about 51%.Similarly,the slope,temperature seasonality,slope direction,lower gravel volume,and wettest season precipitation were the main environmental factors of Picea brachytyla.Among them,the slope and temperature seasonality accounted for about 56.2%of the contribution rate of all environmental factors,which had the most significant impact on its distribution.It shows that the most significant impact on the potential distribution of Picea neoveitchii is soil factor,followed by climate factor;topographic factors and climatic factors have the most significant impact on the potential distribution of Picea brachytyla.(2)The study area was divided into four species-level distribution areas:non-suitable area (0-MTSPS),low suitable area(MTSPS-0.65),medium suitable area(0.65-0.8),and high suitable area(0.8-1).MTSPS is the maximum test sensitivity plus specificity logistic threshold,about 0.47.The potential suitable area of Picea neoveitchii accounts for about 20.18%of the whole study area.Among them,the highly suitable area is about 1165 km~2,accounting for 0.38%of the total area;the moderate suitable area is about 9120 km~2,accounting for about 3.0%of the total area.The low suitable area is about51299 km~2,accounting for 16.8%of the total area.The distribution of suitable areas of Picea neoveitchii in Qinba Mountain is mainly concentrated in Gansu Province,Shanxi Province and Sichuan Province,accounting for 35.25%,34.51%and 30.24%of the total suitable area,respectively.The overall distribution of suitable areas is relatively loose.The potential suitable area of Picea brachytyla accounted for about12.46%of the whole study area,and the highly suitable area was about 1720 km~2,accounting for about0.56%of the whole area.The moderate suitable area is about 8971 km~2,accounting for 2.9%of the total area.The low suitable area is about 27580 km~2,accounting for about 9%of the total area.The distribution of suitable areas of Picea brachytyla in Qinba Mountain was mainly concentrated in Sichuan Province,Gansu Province and Chongqing City,accounting for 46.14%,34.26%and 7.3%of the total suitable area,respectively.Compared with Picea neoveitchii,the distribution area of the current potential suitable area of Picea brachytyla is smaller,but the distribution is more concentrated and the degree of fragmentation is not significant.(3)Under the future climate scenarios,the distribution changes of the suitable area of Picea neoveitchii and Picea brachytyla:It is predicted that the suitable area of Picea neoveitchii in the four climate scenarios of RCP2.6,RCP4.5,RCP6.0 and RCP8.5 in the 2050s accounted for about 19.2%,19.56%,27.06%and 30.31%of the total study area,respectively.In the 2070s,they accounted for 18.85%,18.29%,27.33%and 28.59%,respectively.No matter what kind of climate scenario in the future,the area of highly suitable area and moderately suitable area is higher than that of the current potential medium and high grade suitable area,and the area of low suitable area will show a decreasing trend in the future climate scenario.The degree of change in the suitable area of Picea neoveitchii is proportional to the concentration of greenhouse gas emissions,and the age change has little effect on it.In 2050 s,the percentage of suitable area of Picea brachytyla in the whole study area under the four climate scenarios of RCP2.6,RCP4.5,RCP6.0 and RCP8.5 was about 19%,21.9%,24.9%and 29.5%,respectively.In 2070s,it was 19.6%,24.9%,29.7%and 34.4%,respectively.Under a variety of climate scenarios in the future,the suitable area of each grade of Picea brachytyla is higher than the current potential low,medium and high grade suitable area,and with the increase of age and greenhouse gas emission concentration,the suitable area shows a significant growth trend.It can be seen that the expansion of the suitable area of Picea brachytyla in the future climate scenario is more obvious,while the contraction is minimal.(4)Under the future climate scenarios,the centroid of Picea neoveitchii and Picea brachytyla will migrate:the centroid of the suitable area of Picea neoveitchii will first migrate to the northwest with the increase of greenhouse gas emission concentration in the future climate scenario,and then move back to the northeast when the emission concentration is the highest;the centroid migration distance showed an increasing trend with the increase of greenhouse gas emission concentration,and then the migration distance decreased and gradually stabilized.The centroid of the suitable area of Picea brachytyla showed an eastward migration in the overall trend;with the increase of greenhouse gas emission concentration,the greater the migration distance of the centroid of the suitable area of Picea brachytyla,the higher the overall deviation of the spatial position of the suitable area.
Keywords/Search Tags:Maxent model, Picea neoveitchii, Picea brachytyla, suitable area
PDF Full Text Request
Related items