Marine reserve phenomenon in the Pacific islands

Coinciding with increased numbers of global marine reserves, communities in the Pacific islands are establishing unprecedented number of periodically-harvested and indefinitely-closed marine reserves. An integrated ecological and social comparative methodology is used to examine the motivations and outcomes of reserves in Vanuatu. Communities establish permanent reserves due to concerns about human impacts on reefs, while others establish periodic reserves in response to declining resources. Local knowledge suggests that both reserve types are effective, although validation by underwater surveys was inconclusive. Community support for both reserve types is strong, suggesting that the marine reserve phenomenon in Pacific will continue.     

黄河三角洲北部贝壳堤岛的近期演变

通过不同年代地形图、卫星影像的对比及野外实地测量等,综合分析了黄河三角洲北部开敞型和潮沟型两类贝壳堤岛近50年来的数量和面积变化及其演化特征。结果表明,该区两类贝壳堤岛自20世纪50年代以来在自然和人为因素的共同作用下发生了明显的变化,但其演化特征因岛屿成因的类型差异而各不相同。目前,该区贝壳堤岛群逐渐萎缩,人类活动已成为影响三角洲北部两类贝壳堤岛发育演变的主导因素,特别是潮沟型贝壳堤岛,基本上结束了自然演化的历史,呈现出新的演化特征。     

干旱半干旱地区草原灌丛荒漠化及其生物地球化学循环

干旱和半干旱地区草地生态系统木本植物入侵及其导致的草原灌丛化已经成为全球范 围普遍发生的现象, 是草地沙化和荒漠化的一个重要标志。干旱生态系统中, 此种类型的植被变 化将对区域和全球生物地球化学循环产生显著影响。过度放牧、区域气候干旱化和自然火过程是 导致灌丛入侵和发展的主要控制因子。草原灌丛化过程中, 草地生态系统分布较为均匀的土壤养 分及相关元素在水平和垂直方向发生分异, 关键生命元素C、N、P 、S 生物地球化学循环的变化 将对全球气候变化产生显著作用。全球气候变化与草原灌丛荒漠化之间存在潜在的反馈机制, 人 类扰动的影响将使这种反馈作用变得更加迅速和灵敏。     

The sheltering effect of the Balearic Islands in the hindcast wave field

The sheltering effect of the Balearic Islands in the hindcast wave field was studied for typical Mediterranean wave situations of Llevant, Tramuntana and Mestral and for mild conditions such as the Garbí and Ponent winds. For this purpose, a third generation wave model was applied to the Mediterranean Sea and different patterns of the sheltered areas were found for the various representative situations depending on the wind variability and on the magnitude of the wind speed. From the analysis it was concluded that the sheltered zones created during storms generally persist for short periods of time of the order of 6 h, possibly reaching a maximum of 12 h. In contrast with earlier results obtained for swell dominated ocean areas, it was observed that in this area, due to the short fetches the sea states are mainly local wind seas and thus the wave field behind the islands depends on the local wind.     

Vertical sedimentation units in a barrier island washover fan

Overwash is a major component of a barrier island's response to high energy conditions. Examination of the 19-20 March, 1975, storm deposits at Assateague Island, showed that an overwash sequence could be divided into sedimentation units. Interpretation depends upon defining textural and mineralogical combinations that can be logically ordered as a vertical sequence. If the sequence is depositional and formed from a single material, normal grading usually results; if polymineralogical and erosionally truncated, inverse grading with a top layer of heavy minerals can be formed via an in situ sorting process dependent on disturbance depth and overwash influence.     

ISLANDS AS NOVELTY SITES*

ABSTRACT. Being on the edge, being out of sight and so out of mind, exposes the weakness of mainstream ideas, orthodoxies, and paradigms and foments alternatives to the status quo. Islands are thus propelled as sites of innovative conceptualizations, whether of nature or human enterprise, whether virtual or real. They stand out as sites of novelty; they tend toward clairvoyance; they are disposed to act as advance indicators or extreme reproductions of what is present or future elsewhere. This article, which is essentially bibliographical, celebrates islands as the quintessential sites for experimentation, with reference to the physical sciences, the social sciences, and literature.     

ISLAND SOJOURNS

ABSTRACT. Islands have long held a central place in Western cultures' mythical geographies. They have been associated for centuries with heroic journeys and holy quests, imagined realms of magical transformations. Islands have also been sites of significant rites of passage, and they continue to perform this function in the modern secular world. Today, popular islomania is expressed in the frequency of seasonal sojourning on European and American archipelagos. No longer destinations of permanent residence, islands now provide access to a sense of temporal and spatial rootedness that is no longer available on mainlands. They loom large on the mental maps even of those who rarely, if ever, visit them.     

厦门无居民海岛猴屿生态修复研究与实践

对厦门市无居民海岛猴屿进行生态退化主要原因诊断和生态修复制约因子评估方面的研究,从生物技术和工程技术结合上,提出工程护岸护坡、客土改良、乔-灌-草合理配置及种植品种选择、生态修复管理等生态保育和生态重建措施.部分措施已经有关方面采纳取得较好效果.     

Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot

The mafic volcanic association is made up of OIB, E-MORB and N-MORB in the A'nyemaqen Paleozoic ophiolites. Compared with the same type rocks in the world, the mafic rocks generally display lower Nb/U and Ce/Pb ratios and some have Nb depletion and Pb enrichment. The OIB are LREE-enriched with (La/Yb)N =5―20, N-MORB are LREE-depleted with (La/Yb)N = 0.41―0.5. The OIB are featured by incompatible element enrichment and the N-MORB are obviously depleted with some metasomatic effect, and E-MORB are geochemically intermediated. These rocks are distributed around the Majixueshan OIB and gabbros in a thickness greater than a thousand meters and transitionally change along the ophiolite extension in a west-east direction, showing a symmetric distribution pattern as centered by the Majixueshan OIB, that is, from N-MORB, OIB and E-MORB association in the Dur'ngoi area to OIB in the Majixueshan area and then to N-MORB, OIB and E-MORB assemblage again in the Buqingshan area. By consideration of the rock association, the rock spatial distribution and the thickness of the mafic rocks in the Majixueshan, coupled with the metasomatic relationship between the OIB and MORB sources, it can be argued that the Majixueshan probably corresponds to an ancient hotspot or an ocean island formed by mantle plume on the A'nyemaqeh ocean ridge, that is the ridge-centered hotspot, tectonically similar to the present-day Iceland hotspot.     

人类行为对自然生态系统改变的研究——以大洋岛屿为例

本文聚焦于人类活动在印度洋和中、高纬度大洋中遥远岛屿的表象，着重阐述了人类行为对自然生态系统的影响，文章通过对建筑、采矿、生物引进，以及旅游业开发等人类活动的若干方面的观察和考证，总结认为世界上不存在孤立地域，没有哪一个环境能够保持与世界的经济和政治体系毫不相干。