Can the Stepping Stone Enhance the Establishment, Competition and Distribution of Sown Grassland Species during Recovery on Ex-Arable Lands?

Most diversity restoration projects are not to improve diversity per se, but rather to enhance the presence and abundance of species that are characteristic of reference or target community. The use of Bromus inermis suppresses annual noxious grasses and increases the control of other-forb group these species are also noxious weeds;these may be substituted with another perennial species of the same functional group all through the whole experimental period, as it occurs with other perennial-forb Carduus tenuifolius. A field experiment was conducted on abandoned arable land with sown low and high diversity treatments and natural colonization following typical farming practice for the site. Experimental plots were installed on former agricultural land that had been cropped with (a rotation of) monocultures until the end of 1995. The experiment was organized according to a block design with five replicate blocks. An opposite trend was performed among the colonizer species, because the colonizer grasses were relegated by the high dominance of sown grasses. But at the same time, the sown grasses facilitated the dominance of other colonizer-forbs species;therefore its functional replacement in the community due to sown effect was again tested. However, in natural conditions the other-forbs group was the dominant group, without taking into account the stepping-stone treatment and there was also a functional change of dominance. Our study has demonstrated the restoration effectiveness of species richness at abandoned arable land and may be enhanced by sowing late successional species.

Supplementary Material: Stepping Stone Mechanism: Carrier-Free Long-Range Magnetism Mediated by Magnetized Cation States in Quintuple Layer

The long-range magnetism observed in group-V tellurides quintuple layers is the only working example of carrierfree dilute magnetic semiconductors（DMS）, whereas the physical mechanism is unclear, except the speculation on the band topology enhanced van Vleck paramagnetism. Based on DFT calculations, we find a stable longrange ferromagnetic order in a single quintuple layer of Cr-doped Bi_2Te_3 or Sb_2Te_3, with the dopant separation more than 9 ？. This configuration is the global energy minimum among all configurations. Different from the conventional super exchange theory, the magnetism is facilitated by the lone pair derived anti-bonding states near the cations. Such anti-bonding states work as stepping stones merged in the electron sea and conduct magnetism.Further, spin orbit coupling induced band inversion is found to be insignificant in the magnetism. Therefore, our findings directly dismiss the common misbelief that band topology is the only factor that enhances the magnetism.We further demonstrate that removal of the lone pair derived states destroys the long-range magnetism. This novel mechanism sheds light on the fundamental understanding of long-range magnetism and may lead to discoveries of new classes of DMS.

Generalized Stepping Stone Model with Ξ-resampling Mechanism

A generalized stepping stone model withΞ-resampling mechanism is a two dimensional probability-measure-valued stochastic process whose moment dual is similar to that of the classical stepping stone model except that Kingman’s coalescent is replaced byΞ-coalescent.We prove the existence of such a process by specifying its moments using the dual function-valuedΞ-coalescent process with geographical labels and migration,and then verifying a multidimensional Hausdorff moment problem.We also characterize the stationary distribution of the generalized stepping stone model and show that it is not reversible if the mutation operator is of uniform jump-type.

A STEPPING STONE

The Hindi language is helping young people in China look beyond stereotypes and discover‘Incredible India’In the eyes of many Chinese,India may not be a top destination for frst-time traveling or higher studies.But Li Yalan is an exception.She was the frst Chinese student admitted by the Mahatma Gandhi International

Stepping Stones for Migrant Kids

An interview with Corinne Hua,Founder and Executive Director of Stepping Stones对话铺路石青少年发展中心创始人、项目总监华柯林Corinne Hua founded Stepping Stones in 2006,whose volunteers teach English to migrant children for free.These classes are perhaps the children’s only opportunity to learn standard and proper