海岛城镇空间扩展及景观生态演变研究 ——以舟山为例     

樊超  桂峰  赵晟 《海洋通报》2019,38(4):447-454

本文以舟山本岛为研究对象,通过7景Landsat系列遥感影像,获取了1985-2015年7个时期内的5种地物信息。在此基础上,引入4个空间分析指标,分析了城镇扩展方位特征、城镇扩展强度及扩展速度特征、景观格局变化特征,并对影响城镇扩展的自然环境因素进行空间分析,对社会经济因素进行相关性分析。结果表明:(1)舟山本岛城镇扩展在空间方位上呈现"串珠状"的非典型蔓延特征,且在本岛第四象限扩展最显著;(2)城镇空间扩展可划分为三个阶段:城镇雏形阶段(1985-1995年)、城镇生长阶段(1995-2010年)及城镇成熟阶段(2010-2015年);(3)城镇雏形阶段,城镇"向中部绿心"扩展,岛陆森林面积减少了10.34 km2;城镇生长阶段,城镇"向海"扩展,25.10 km2周边海域经围垦转变为耕地及建设用地;城镇成熟阶段,城镇扩展"向海"与"向中部绿心"并存,对海岛生态系统陆海两侧均造成压力;(4)城镇空间扩展的空间指向主要位于海拔20 m以下,坡度10°以下的山谷、沿岸平原及围垦区。本岛人口数、房地产投入、GDP总量及路网总长等因素与城镇扩展相关性最显著。  相似文献   

The New South Wales Travelling Stock Route and Reserve (TSR) network: historical extent,spatial distribution and drivers of loss 1884–2017     

Bryce Vella  Prue Gonzalez 《The Australian geographer》2020,51(1):87-103

ABSTRACT

The Travelling Stock Route and Reserve (TSR) network is an historical grazing reserve network under threat, where public alarm has continued over the potential sale of reserves. Present debate on the future of the TSRs is often hindered by a lack of data, as knowledge of the historical extent of TSRs is deficient. This paper documents the original extent of the New South Wales TSR network and changes during 1884–2017, and discusses the key drivers of reserve loss since the late nineteenth century. Research using archived literature showed that, in 1884, the New South Wales TSR network comprised 4,414,690?ha. Comparisons of TSR acreage from that time with present estimates revealed that the reserve network has declined by 54% since its inception. Most reductions in TSR area during 1884–2017 have occurred in the Eastern (83%) and Central (82%) regions of the state, where competing land demands are greatest. Technological changes in transport, environmental pressures and economic changes in the grazing industry were identified as key drivers of TSR loss. These findings support concerns over the efficacy of the TSR reserve network, where the extent and impacts of past government decisions to sell off TSRs has been grossly under-estimated.  相似文献   

温度对微食物网生物代谢的影响     

张武昌  赵苑  董逸  赵丽  李海波  肖天 《海洋科学》2018,42(10):137-145

生态学代谢理论(metabolic theory of ecology, MTE)指的是生物的代谢速度随着温度的升高而增加,随生物个体大小(即生物量)的增加而异速增长。根据MTE理论可预测异养过程与自养过程对温度的反应不同,低温对异养代谢的抑制要明显;而随着温度升高,异养代谢升高的速度比自养代谢升高的速度要快。MTE理论可以对海洋浮游微食物网生物的代谢研究进行理论指导,用于解释一些低温造成的海洋浮游生态学现象,以及预测全球变暖的影响。多年来人们一直根据MTE理论开展理论分析和实验检验,发现低温会抑制细菌和微型浮游动物的生长,并可以降低微型浮游动物的摄食率。春季高纬度海区的海水温度会抑制细菌的生长,而浮游植物则几乎不受影响,从而造成春季水华发生。温度和底物浓度是冷海(水温≤4℃)细菌生长率低的原因,但在永冷海(周年温度≤4℃的海区,包括极地海区和深海的大部分)中究竟是低温还是底物浓度限制了细菌的生长率仍被争论。全球变暖的预测认为本世纪海洋表层温度会升高2～6℃。根据MTE理论,温度升高对自养和异养过程的影响不同,围隔实验证明全球变暖将导致水华与细菌、水华与微型浮游动物的时滞变小,促进微型浮游动物对细菌和浮游植物的摄食,改变有机物质自养生产和异养消耗之间的平衡,使更多的物质和能量进入呼吸作用,使得生态系统变得更加异养。但在温度升高对海洋细菌生长效率和细菌生物量变化的研究方面,MTE理论还有一定的局限性,需要进一步的理论分析和实验检验。  相似文献   

海洋浮游植物薄层的研究进展     

王云峰  颜天  于仁成  张清春  孔凡洲  周名江 《海洋科学》2020,44(7):86-95

浮游植物薄层是指位于水体次表层、厚度从几厘米到几米的高丰度浮游植物分布层。与大洋相比，在河口、海湾和近海的浮游植物薄层往往分布浅、强度大，具有明显的时空变化。浮游植物薄层的形成和维持不仅受到层化、楔入、剪切等物理过程的调控，也与浮游植物的生长、聚集及浮游动物的差异化捕食等生物生态学过程有关，目前围绕浮游植物薄层的形成机制已提出了趋旋俘获等假说。浮游植物薄层对其生长、繁殖、防御等具有重要意义，有的浮游植物薄层聚集了大量的有毒有害藻，与有害藻华的发生关系密切。深入研究浮游植物薄层的成因，将为阐明有害藻华的发生机制和有效监测提供重要依据。  相似文献   

星康吉鳗生物学与生态学的研发现状与展望     

杨浩  史宝  牛化欣  张代强  李静 《海洋科学》2020,44(6):152-158

星康吉鳗（Conger myriaster）具有较高的营养价值和经济价值，是中国和日本重要捕捞对象之一，在中国海鳗类加工出口中占有重要的地位，关于其研究越来越受到关注。星康吉鳗具有较高的产业化养殖潜力和广阔的养殖前景，亟待开展人工增养殖以满足国内外市场需求。作者总结了星康吉鳗生物学方面的形态特征、食性特点、繁殖习性、栖息、洄游、种质遗传特征，生态学方面的温度、盐度、光照、溶氧适应以及捕捞、人工养殖方式等方面的研究成果，并在此基础上对未来星康吉鳗的研究方向进行了展望，以期为星康吉鳗的资源保护和增养殖产业可持续发展提供理论参考。  相似文献   

Mass mortality of the fan mussel,Pinna nobilis in Turkey (eastern Mediterranean)     

Fikret Öndes  Vahit Alan  Barış Akçalı  Harun Güçlüsoy 《Marine Ecology》2020,41(5):e12607

This study reported the mass mortality events (MMEs) of Pinna nobilis based on diving surveys in Turkey. Data were collected across 12 sites in the Aegean Sea, and one site in the Sea of Marmara, within the period of June-September 2019. The results showed that a low mortality rate of 10% was found in the Sea of Marmara, and a MME was not detected for this area. In contrast, 97% mortality was recorded for the P. nobilis population distributed in the Turkish Aegean Sea. This discrepancy might be related to the seawater temperature and salinity values of these two seas. The waters of the Sea of Marmara were colder and less salty than the Aegean Sea. The findings highlighted the importance of protecting the healthy population of critically endangered fan mussels in the Sea of Marmara. It was recommended that sound management plans comprising of monitoring, enforcement and public awareness activities could be implemented in order to achieve this.  相似文献   

从中华鲟(Acipenser sinensis)生活史剖析其物种保护:困境与突围     

危起伟 《湖泊科学》2020,32(5):1297-1319

国家一级保护动物中华鲟(Acipenser sinensis)自然繁殖已连续中断3年(2017 2019年),自然种群濒临灭绝.本文归纳了中华鲟生活史各阶段的生态需求,指出:葛洲坝阻隔是导致中华鲟自然种群衰退的根本原因,三峡等长江上游特大型梯级水电工程的相继蓄水运行是导致中华鲟自然繁殖中断的关键因素,河道冲刷、航道疏浚与挖沙、防洪及城市景观工程等人类活动使中华鲟仔稚鱼栖息地丧失,进而导致补充群体减少,造成繁殖群体持续萎缩.近40年来,对给予高度期望的补偿中华鲟自然种群衰退的中华鲟人工增殖放流措施没有得到科学有效地实施,造成人工干预力保中华鲟自然种群延续的希望几近破灭.本文探讨了近40年来在中华鲟保护认识、管理、决策和机制上存在的误区与不足,提出以长江十年休渔为契机,亟需以《中华鲟拯救行动计划(2015-2030年)》为纲领,推进落实:1)实施"陆-海-陆"保种工程,恢复人工群体的生物学自然特性; 2)大幅度提升科学有效的人工增殖放流; 3)改善产卵场环境,放流人工培育亲本以恢复葛洲坝下中华鲟自然繁殖; 4)新建旁通道仿自然产卵场,扩大自然繁殖; 5)修复索饵场等关键栖息地,提高子代存活率.唯有以恢复中华鲟自然繁殖为核心,实施中华鲟从出生到繁殖全生活史周期(15年)的长期系统性保护,才有望延续和恢复中华鲟自然种群.中华鲟个体大、寿命长、洄游范围广,是长江水生态系统的旗舰种和伞护种,保护好中华鲟对于实现人与自然和谐共处,推动长江流域经济社会绿色可持续发展具有重要意义.  相似文献   

Tradeoffs in carbon commodification: A political ecology of common property forest governance     

《Geoforum》2015

Carbon markets have gained traction worldwide as an ostensibly win–win solution to climate change, providing low-cost emission reductions in the Global North and sustainable development in the Global South. However, sustainable development and livelihood co-benefits have largely failed to materialize in a range of carbon offset projects, particularly those in forest communities. While some scholars explain this failure as an outcome of fundamental tradeoffs between market efficiency and sustainable development, others argue that institutions of common property land tenure can resolve tradeoffs and generate important co-benefits for local communities. Using a political ecology approach, integrating insights of Karl Polanyi and Noel Castree on the commodification of nature and evidence from a carbon forestry project in Chiapas, Mexico, this article grapples with the ways in which carbon market requirements shape forest governance within common property tenure arrangements. I argue that the centralization of forest governance and decision making into the hands of project implementers and brokers, the necessity for legible land rights and boundaries, and the technical requirements for measurement, calculation, and monitoring of carbon have reshaped forest governance in ways that have undermined the social and ecological benefits often associated with common property management schemes. This research therefore demonstrates that so-called tradeoffs between market efficiency and equitable sustainable development goals may not be inherent to carbon forestry and calls into question the reliance on disembedding market mechanisms for climate change mitigation in forest ecosystems. As such, this work has important implications for REDD+.  相似文献   

内蒙古达里湖全新世有机碳氮同位素记录与环境演变   总被引：1，自引：0，他引：1  

范佳伟  肖举乐  温锐林  翟大有  王旭  崔琳琳  Shigeru Itoh 《第四纪研究》2015,35(4)

内蒙古中东部的达里湖为一水文封闭型湖泊,位于现今东亚夏季风的北部边缘区,对区域环境变化十分敏感.本文对达里湖沉积中心提取的岩芯(DL04沉积岩芯)顶部8.5m沉积物进行了有机地球化学分析.15个全岩样品有机质的放射性碳测年结果表明:岩芯顶部8.5m涵盖了过去大约11500年.按约50年分辨率分析的225个总有机碳(TOC)、总氮(TN)含量、总有机碳/总氮(C/N)原子比值数据以及221个有机碳和有机氮稳定同位素(δ13C和δ13C)数据,详细揭示了全新世东亚夏季风边缘区的水文和生态变化历史.在距今11500 ～ 9800日历年(ca1.aB.P.)期间,所有地球化学指标均呈逐渐增大趋势,指示入湖河流逐渐增强,达里湖开始扩张,水生植物生产率逐渐升高;在9800 ～ 7700cal.aB.P.期间,TOC和TN含量以及C/N比值维持稳定高值,δ13C和δ15N值较小,指示湖泊维持高湖面状态,陆源输入和浮游植物生产率较高;在7700～ 5900cal.aB.P.期间,C/N比值和δ15N维持低值,TOC和TN含量呈现更高值,并且波动变化,δ13C值逐渐增大,表明湖面维持高水平,湖水显著变暖,浮游植物生产率显著升高,流域植被大幅度扩张;在5900 ～ 4850cal.aB.P.期间,TOC和TN含量,C/N比值以及δ13C值显著减小,δ15N值显著增大,暗示地表径流显著减弱,达里湖湖面显著下降,湖泊生产率快速下降;从4850cal.a B.P.开始,TOC和TN含量以及C/N比值呈逐渐减小趋势,δ13C和δ15N值呈逐渐增大趋势,表明湖面逐渐下降,湖水盐度、碱度升高,湖水可能变冷,湖泊生产率逐渐下降,流域植被收缩.全新世东亚夏季风边缘区水文和生态环境的变化可能直接或间接受北半球夏季太阳辐射量和区域季风降水强度的共同控制.  相似文献   

Seasonal change mediates the shift between resource and pollen limitation in Hedysarum scoparium (Fabaceae)     

ChengChen Pan  Qi Feng  HaLin Zhao  XueYong Zhao  LinDe Liu  JiLiang Liu  Li Zhang  Jin Li 《寒旱区科学》2015,7(1):0094-0098

Theory suggests that with sufficient environmental variation, pollen limitation might be observed at some places or times, and resource limitation at others, but there are no empirical data about the effect of seasonal change on the variation of pollen limitation and resource limitation within a flowering season. In this study, we examined pollen and resource limitation by comparing fruit set and seed production in natural- and hand-pollinated Hedysarum scoparium flowers in the middle reaches of the Hexi Corridor region, China, in 2010. We also described a role for the first substantial autumn rainfall in mediating a shift between pollen and resource limitation in H. scoparium, but did not analyze this experimentally. Our results indicated that H. scoparium was resource limited at peak flowering during the summer, and was pollen limited at peak flowering during the autumn. The seasonal change (summer to autumn) mediated the shift between pollen and resource limitations in H. scoparium. The shift timing depended on the date of the first autumn rainfall in 2010. Changes in the first substantial rainfall in autumn may affect fruiting of H. scoparium, thus affecting population persistence of this species and development/structure of the local ecosystem if such conditions persist.  相似文献