Predicting the Potential Distribution of Rubia cordifolia L.in China

[Objectives]We intend to conduct a study to predict habitat suitability and geographic distribution of Rubia cordifolia L.,to find the most suitable ecological environment for its growth,and to provide a theoretical basis for the development and cultivation of R.cordifolia L.industry.[Methods]Based on the environmental factors and the occurrence data,we predicted the potential geographic distribution of R.cordifolia L.in China by combining the MaxEnt model and ArcGIS.[Results]The training set and test set AUC were respectively 0.963 and 0.946,indicating that the MaxEnt model predicted well.The wettest monthly precipitation,precipitation in July,precipitation of driest season,and average monthly temperature in September and April were the dominant environmental factors affecting the distribution of R.cordifolia L.The highly habitable areas were mainly concentrated in central,eastern and northern China.[Conclusions]The results of this study can be used as a reference for the development of R.cordifolia L.industry in related areas.

Large along-axis variations in magma supply and tectonism of the Southeast Indian Ridge near the Australian-Antarctic Discordance

We analyzed seafloor morphology and geophysical anomalies of the Southeast Indian Ridge(SEIR) to reveal the remarkable changes in magma supply along this intermediate fast-spreading ridge. We found systematic differences of the Australian-Antarctic Discordance(AAD) from adjacent ridge segments with the residual mantle Bouguer gravity anomaly(RMBA) being more positive, seafloor being deeper, morphology being more chaotic, M factors being smaller at the AAD. These systematic anomalies, as well as the observed Na8.0 being greater and Fe8.0 being smaller at AAD, suggest relatively starved magma supply and relatively thin crust within the AAD.Comparing to the adjacent ridges segments, the calculated average map-view M factors are relatively small for the AAD, where several Oceanic Core Complexes(OCCs) develop. Close to 30 OCCs were found to be distributed asymmetrically along the SEIR with 60% of OCCs at the northern flank. The OCCs are concentrated mainly in Segments B3 and B4 within the AAD at ~124°–126°E, as well as at the eastern end of Zone C at ~115°E. The relatively small map-view M factors within the AAD indicate stronger tectonism than the adjacent SEIR segments.The interaction between the westward migrating Pacific mantle and the relatively cold mantle beneath the AAD may have caused a reduction in magma supply, leading to the development of abundant OCCs.