模糊图论在山西植被区划中的应用

本文用模糊图论的最大树方法对山西植被区划进行了数量分类研究,将山西植被分为2个植被地带,6个植被地区,17个植被小区。与在植物群落学中应用的模糊聚类分析和其它方法相比,模糊图论的最大树方法直接依模糊相似系数矩阵得到树状图,从而避免了相似系数矩阵复杂的合成运算,而分类结果不仅更具直观性,而且也是令人满意的。我们认为模糊图论应用于植被区划是合适的。     

Subantarctic flowering plants: pre‐glacial survivors or post‐glacial immigrants?

Aim The aim here was to assess whether the present‐day assemblage of subantarctic flowering plants is the result of a rapid post‐Last Glacial Maximum (LGM) colonization or whether subantarctic flowering plants survived on the islands in glacial refugia throughout the LGM. Location The circumpolar subantarctic region, comprising six remote islands and island groups between latitudes 46° and 55° S, including South Georgia in the South Atlantic Ocean, the Prince Edward Islands, Îles Crozet, Îles Kerguelen, the Heard Island group in the South Indian Ocean and Macquarie Island in the South Pacific Ocean. Methods Floristic affinities between the subantarctic islands were assessed by cluster analysis applied to an up‐to‐date dataset of the phanerogamic flora in order to test for the existence of provincialism within the subantarctic. A review of the primary literature on the palaeobotany, geology and glacial history of the subantarctic islands was carried out and supplemented with additional palaeobotanical data and new field observations from South Georgia, Île de la Possession (Îles Crozet) and Îles Kerguelen. Results First, a strong regionalism was observed, with different floras characterizing the islands in each of the ocean basins, and endemic species being present in the South Indian Ocean and South Pacific Ocean provinces. Second, the majority of the plant species were present at the onset of accumulation of post‐glacial organic sediment and there is no evidence for the natural arrival of new immigrants during the subsequent period. Third, a review of geomorphological data suggested that the ice cover was incomplete during the LGM on the majority of the islands, and ice‐free biological refugia were probably present even on the most glaciated islands. Main conclusions Several independent lines of evidence favour the survival of a native subantarctic phanerogamic flora in local refugia during the LGM rather than a post‐LGM colonization from more distant temperate landmasses in the Southern Hemisphere.     

Tribal hands and minority votes: ethnicity,regionalism and elections in Iran

Ethnic politics is a serious domestic challenge in Iran. Non-Persian communities are mobilizing to claim their rights and to demand representation in a system that activists claim is biased against minorities and the peripheral regions. Yet the inner workings of contemporary Iranian ethnic politics are largely understudied. This article explores recent evolutions in the role that ethnicity, regionalism and tribalism plays in Iranian domestic politics. It focuses on how these interconnected factors figured in the 2013 presidential and local council elections in Iran in a particular province that has a history of ethnic tensions. Incidentally, these elections brought Hassan Rouhani, a moderate cleric, to power as president. Among his electoral promises was to end the securitization of the minority issue. This article illustrates some of the barriers to a transformative ethnic politics – barriers that political leaders will have to overcome to enact real change.