Chronologies of glacial advances during the last glacial period in the Nyainqentanglha mountain range may provide constraints on the past climate in a transition zone of the Asian monsoon. We present 15 new Be exposur...Chronologies of glacial advances during the last glacial period in the Nyainqentanglha mountain range may provide constraints on the past climate in a transition zone of the Asian monsoon. We present 15 new Be exposure ages from two moraines in the Payuwang valley, on the north slope of the range. The inner moraine has exposure ages ranging from 18.0±1.7 to 30.6±2.8 ka （n=10）, with a mean age of 23.8±4.0 ka, corresponding to the global Last Glacial Maximum （LGM）. The outer moraine yields exposure ages ranging from 18.0±1.6 to 39.9±3.7 ka （n=5）. Evidence for weathering leads us to view the oldest age as a mini mum age, placing moraine formation during MIS3. Chronologies from the last glacial period from south slope of the Nyainqentanglha support this interpretation. Thus, there appears to have been a local LGM （LLGM） during MIS3 and a more limited glacial advance during the global LGM. Glacial advances during MIS3 in the Nyainqentanglha may correlate with mil lennialscale climate change （Heinrich events）.展开更多
The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially ...The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially in alpine–arctic ecosystems.Here,we aim to test if the previously proposed hypothesis based on the richness–environment relationship could explain the variation in richness patterns of the typical alpine–arctic herbaceous genus Saxifraga.Using a newly compiled distribution database of 437 Saxifraga species,we estimated the species richness patterns for all species,narrow-and wide-ranged species.We used generalized linear models and simultaneous autoregressive models to evaluate the effects of contemporary climate,habitat heterogeneity and historical climate on species richness patterns.Partial regressions were used to determine the independent and shared effects of different variables.Four widely used models were tested to identify their predictive power in explaining patterns of species richness.We found that temperature was negatively correlated with the richness patterns of all and wide-ranged species,and that was the most important environmental factor,indicating a strong conservatism of its ancestral temperate niche.Habitat heterogeneity and long-term climate change were the best predictors of the spatial variation of narrow-ranged species richness.Overall,the combined model containing five predictors can explain ca.40%–50%of the variation in species richness.We further argued that additional evolutionary and biogeographical processes might have also played an essential role in shaping the Saxifraga diversity patterns and should be considered in future studies.展开更多
基金supported by National Natural Science Foundation of China(Key Program)(Grant No.41230523)Strategic Priority Research Program(B) of the Chinese Academy of Sciences(Grant No.XDB01020300)National Natural Science Foundation of China(General Program)(Grant No.40971017)
文摘Chronologies of glacial advances during the last glacial period in the Nyainqentanglha mountain range may provide constraints on the past climate in a transition zone of the Asian monsoon. We present 15 new Be exposure ages from two moraines in the Payuwang valley, on the north slope of the range. The inner moraine has exposure ages ranging from 18.0±1.7 to 30.6±2.8 ka （n=10）, with a mean age of 23.8±4.0 ka, corresponding to the global Last Glacial Maximum （LGM）. The outer moraine yields exposure ages ranging from 18.0±1.6 to 39.9±3.7 ka （n=5）. Evidence for weathering leads us to view the oldest age as a mini mum age, placing moraine formation during MIS3. Chronologies from the last glacial period from south slope of the Nyainqentanglha support this interpretation. Thus, there appears to have been a local LGM （LLGM） during MIS3 and a more limited glacial advance during the global LGM. Glacial advances during MIS3 in the Nyainqentanglha may correlate with mil lennialscale climate change （Heinrich events）.
基金supported by the National Natural Science Foundation of China(#31770566,#31770232)Biodiversity Survey,Observation and Assessment Program of Ministry of Ecology and Environment of China and the Fundamental Research Funds for the Central Universities of China(#SCU2021D006,#LZUJBKY202035)D.M.N.thanks Instituto Serrapilheira/Brazil(Serra-1912-32082)and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—CAPES/PrInt/Brazil(88887.474387/2020-00)for financial support during the time this research was carried out.
文摘The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially in alpine–arctic ecosystems.Here,we aim to test if the previously proposed hypothesis based on the richness–environment relationship could explain the variation in richness patterns of the typical alpine–arctic herbaceous genus Saxifraga.Using a newly compiled distribution database of 437 Saxifraga species,we estimated the species richness patterns for all species,narrow-and wide-ranged species.We used generalized linear models and simultaneous autoregressive models to evaluate the effects of contemporary climate,habitat heterogeneity and historical climate on species richness patterns.Partial regressions were used to determine the independent and shared effects of different variables.Four widely used models were tested to identify their predictive power in explaining patterns of species richness.We found that temperature was negatively correlated with the richness patterns of all and wide-ranged species,and that was the most important environmental factor,indicating a strong conservatism of its ancestral temperate niche.Habitat heterogeneity and long-term climate change were the best predictors of the spatial variation of narrow-ranged species richness.Overall,the combined model containing five predictors can explain ca.40%–50%of the variation in species richness.We further argued that additional evolutionary and biogeographical processes might have also played an essential role in shaping the Saxifraga diversity patterns and should be considered in future studies.
