| Alsophila spinulosa is an endangered relict tree-like fern species,In the context of rapid global climate change,studying the changes of the potential suitable habitat(PSH)for Alsophila spinulous in different periods can help to better understand the mechanism behind these changes,and provide scientific basis for its protect and management effectively.Based on 2.5'-resolution global environmental data and MaxEnt model,in this thesis,the global PSH for Alsophila spinulosa in the Last Glacial Maximum and the Mid Holocene were reconstructed,the global PSH under current and future climates were simulated,and the changes between various periods were analyzed.The dominant factors affecting the geographic distribution of Alsophila spinulosa were analyzed.The trajectory of the geometric centroid of the PSH for Alsophila spinulosa in different periods were mapped.Furthermore,considering factors such as bioclimate,topography,soil,vegetation,and land cover,the PSH for Alsophila spinulosa in China based on 30"-resolution environmental data under current climates were modelledMajor conclusions are as follows:(1)On the global scale,in the Last Glacial Maximum and the Mid Holocene,the global PSH area for Alsophila spinulosa was 9.2 million km~2 and 6.8 million km~2,respectively,which were much larger than that in current times.In addition to climate change,the rise and fall of sea level,the exposure and submergence of the continental shelf as well,had significant effects on the distribution of PSH for Alsophila spinulosa.(2)Under current climates,the global PSH for Alsophila spinulosa is 3.5 million km~2,which is mainly located in Asia,with a small amount distribution in North America,Central America,Madagascar,La Réunion,Mauritius,Seychelles,New Zealand island,New Caledonia island and Fiji island.The PSH of Alsophila spinulosa in China is about 1.8 million km~2,accounting for 55%of that in Asia.The dominant ecological factors suitable for Alsophila spinulosa existence are:precipitation of the warmest quarter(>600mm),precipitation in July(200mm?800mm),precipitation of the driest month(50mm?240mm),temperature seasonality(360?600),and mean diurnal range(2??6?).(3)In the future,based on different Shared Socio-economic Paths(SSPs),under the green development path,the global area of the PSH for Alsophila spinulosa is expected to decrease by 7.8%during 2041–2060,and then increase by 3.2%during 2081–2100;under the moderate development path,its area is expected to increase by 2.9%during2041–2060 and by 7.2%during 2081–2100;under the normal development path,its area is expected to increase by 3.3%during 2041–2060 and by 5.3%during 2081–2100.(4)From the Last Glacial Maximum to the Mid Holocene via present to the end of the 21th century,the geometric centroids of the PSH for Alsophila spinulosa move northeastern in general.(5)On the region scale,The PSH for Alsophila spinulosa in China is 9.3 hundred thousand km~2,mainly distributed in Yunnan,Guizhou,Sichuan,Guangdong,Guangxi,Hainan,and Taiwan.The dominant climate factors suitable for Alsophila spinulosa existence include precipitation of the driest month(>50mm),precipitation in July(200?700mm),temperature seasonality(200?800),precipitation of the warmest quarter(>700mm).Vegetation type is one of the dominant factors,and the main vegetation types of the PSH of Alsophila spinulosa in China are cultivated vegetation types,coniferous forests,broad-leaved forests,shrubs,grasses,etc.(6)This study revealed the dominant factors affecting the geographic distribution of Alsophila spinulosa,and depicted the distribution of PSH for Alsophila spinulosa at the Last Glacial Maximum and the Mid-Holocene,and at the end of this century.The research results may provide a map to find the undiscovered natural distribution of Alsophila spinulosa,avoid the risk areas of the introduction,and plan the suitable introduction and cultivation areas.It is also a reference to control the artificial climate environment of Alsophila spinulosa cultivation according to its niche characteristics. |
PDF Full Text Request