我国古代扬子鳄减少原因考证

曾经在我国古代黄河、长江流域生存的扬子鳄(Alligator sinensis)如今已成濒危物种,其减少原因在长江流域与黄河流域是有区别的。黄河流域扬子鳄灭绝与栖息地生态恶化有关,而长江流域扬子鳄的减少主要是因古人稻作生产所致,此外气温变化和人类捕杀也影响了它的生存数量。     

水文变异下的黄河流域生态流量

使用t检验和Mann-Whitney U检验对黄河干流7个水文站月均流量进行水文变异分析,探讨了水文变异成因,在此基础上,确定变异前各月月均流量序列最适概率分布函数,将概率密度最大的月平均流量定义为河道内生态流量。经与Tennant法、最小月平均流量发和逐月径流法比较,考虑水文变异的河道内生态流量计算方法是可行、合理的。水文变异后,黄河干流7水文站月均流量普遍减少,月均流量满足河道内生态流量的频率降低。研究结果表明,人类活动是黄河生态系统水环境恶化的重要原因。在流域生态管理中,确保变异后生态流量满足频率与变异前相当。研究对于理解在当前气候变化与人类活动双重影响下,干旱半干旱区流域水资源科学管理具有一定理论与现实意义。     

洪水脉冲理论及其应用

洪水脉冲理论是继河流连续统理论之后的第4个河流生态理论,主要阐述洪水脉冲驱动下,河流与其洪泛区之间的横向水力联系对河流洪泛区系统进程的重要性,强调洪水脉冲的重要性及河流洪泛区系统的整体性。本文论述洪水脉冲理论的概念模型、主要观点及其在河流洪泛区系统的应用进展。洪水脉冲理论的应用主要体现在三方面在洪水塑造河流洪泛区系统地貌进程方面,侧重于河流形态的“主导径流”研究,成果不断提升;在生物地球化学循环上,以对氮的研究为主,提出洪水脉冲是河流洪泛区新陈代谢及生物地球化学循环的重要驱动力;在生物进程上,集中在对大型植物和以水鸟和鱼类为代表的动物研究上。文中提出要提高河滨生物量,并重建全局的生物多样性,应提倡人为的洪水脉冲。对于干旱半干旱区湿地水鸟的保护核心是洪水发生频率和淹没范围对水鸟繁殖及避难的作用,以及水在湿地景观中的分配,这一点对于中国松嫩平原西部干旱半干旱区湿地水鸟的保护具有重要意义。洪水脉冲理论的提出是基于对热带亚马逊河的观察实验,随着其在其它类型区域的推广应用,除洪水脉冲以外的其它因素的作用突现出来,人类干扰洪水脉冲的生态效应亦愈来愈显现。因此,有必要加强洪水脉冲与其它环境因子的耦合作用,及这种作用在人类干扰活动下,导致的河流洪泛区系统进程变化的研究,提出更具有普适性的洪水脉冲理论。     

纵纹腹小鸮繁殖习性观察

1997～ 1 999年的 3～ 7月在山西芦芽山国家级自然保护区 ,对纵纹腹小的繁殖习性进行了观察 ,其内容包括栖息地、营巢环境、种群密度、食物组成等     

黑叶猴在喀斯特石山生境的觅食活动

2002 年 8 月至2003 年 7 月,对一群生活在广西扶绥珍稀动物保护区内孤立石山中的黑叶猴进行观察,通过收集有关栖息地利用的数据,从中探讨栖息地的破碎化对其生态习性的影响.研究结果表明：猴群的觅食活动在石山各个部位的分布存在着显著差异,它们更偏好在山腰觅食（66.1%）,而较少利用山脚（18.6%）和山顶（15.3%）.从横向水平来看,猴群的觅食活动主要集中在6个觅食斑块,总面积为7.94 hm^2,约占栖息地面积的18.9%.觅食斑快中黑叶猴喜食食物的植株密度明显高于非觅食斑块.虽然树叶在黑叶猴食物组成中占绝大部分,但其食物组成具有明显的季节性变化.与之相对应,猴群对觅食斑块的利用也表现出明显的季节性差异.     

四川扭角羚春冬季对栖息地的利用初步研究

1998年3月至1999年2月,在四川省青川县唐家河自然保护区,对四川扭角羚（Budorcas taxicolor tibetana)春冬季对栖息地的利用进行了初步研究。结果表明,影响四川扭角羚春季栖息地利用的主要生态因子为人为干扰,植被型、乔木大小、乔木距离,乔木密度、食物丰富度,海拔,坡位、郁闭度,影响冬季栖息地利用的主要生态因子为人为干扰。植被型,乔木距离,灌木大小,灌木密度,动物干扰度,乔木大小、灌木距离,坡位,郁闭度,水源,四川扭角羚春冬季栖息地利用的分离主要表现为食物丰富度,乔木大小,乔木密度,乔木距离,植被型,水源,坡位等生存因子的分离。     

纵纹腹小NFDA1繁殖习性观察

1997～1999年的3～7月在山西芦芽山国家级自然保护区,对纵纹腹小NFDA1的繁殖习性进行了观察,其内容包括栖息地、营巢环境、种群密度、食物组成等.     

海绵城市建设对流域海绵体生态水文过程的改善

快速城市化驱动的不透水面比例增加是引起流域洪峰和径流总量增加的直接原因,海绵城市建设通过生态基础设施网络构建增加流域透水面比例,是重构流域生态水文过程的重要途径。但是海绵城市建设在流域海绵体生态水文过程中发挥的作用尚不清楚。本文以深圳市布吉河流域洪湖片区为例,通过雨季水文过程要素在线连续监测来确定海绵城市建设是否改善洪湖片区生态水文过程。结果表明,中观尺度上,雨季降雨量对洪湖片区地表径流总量无直接影响,降雨强度显著影响洪湖片区地表径流峰值流量（P<0.05）,日降雨量对布吉河水质影响极显著（P<0.01）。洪湖片区通过28.3%（0.85 km2）海绵面积建设,透水面比例提升,以生物滞留设施和透水铺装等强化片区蒸散和下渗过程,减少雨季径流97.2%（248.72万m3）,削减典型降雨峰值流量98.2%以上,降低易涝点积水水位至7.8 cm以下,2.8%形成河川径流（布吉河）,海绵面积（比例）和地表径流量削减无直接量化关系。洪湖片区污染物截留时空随保水能力得到提升,控制排放SS月均浓度均低于15.60 mg/L,污染物通过径流裹挟进入布吉河的总量和速率降低,促使布吉河黑臭消除、水质提升至IV类。海绵城市建设对微观尺度生态水文过程的影响与中观尺度存在差异,降雨量等因素与典型项目生态水文过程量化关系不明显。学校、道路和社区公园利用绿色屋顶、透水铺装等强化下渗、蒸散,可削减雨季径流99.0%以上、削减峰值流量97.0%以上,控制SS月均浓度低于17.10 mg/L。总之,以上研究结果强烈表明海绵城市中微观尺度源头减排设施和调蓄设施的耦合建设模式可以削减洪湖片区径流总量、峰值流量、积水水位和径流污染,是一种改善相似流域生态水文过程的有效途径。     

岷山、邛崃山山系大熊猫栖息地生态安全综合评价

【目的】岷山与邛崃山系是大熊猫的重要栖息地,但由于该地区干扰、栖息地破碎化等原因,野生大熊猫的生存和种群复壮仍然存在风险。基于大熊猫习性和生存需求来评价其栖息地生态安全,对于更好地保护野生大熊猫种群、明确保护的地理重点,具有重要现实意义。【方法】以岷山山系、邛崃山山系范围内各市、区、县为对象,收集并选择最新的社会、地理、生物三大类目中具有代表性的12个因子作为评价指标,运用层次分析法和主成分分析法相结合的方法对该地区大熊猫栖息的生态安全进行综合评价。【结果】岷山、邛崃山中部的平武县、宝兴县的生态安全指数最高;彭州市、都江堰市和邛崃县等成都的周边地区生态安全指数较低,主要原因是人类活动的影响;都江堰市北部和汶川县域内为大熊猫的重要栖息地,但其生态安全指数较低,需要进一步的保护、管理和恢复;平武中部、松潘、茂县等地区生态安全指数较高,可作为大熊猫潜在栖息地进行保护。【结论】岷山大熊猫栖息地的生态安全指数总体上高于邛崃山系,但都存在明显的空间异质性。本研究结果可为野生大熊猫生态廊道的建设、圈养大熊猫放归地点选择等工作提供科学依据。     

小浪底水库排沙对黄河鲤鱼的急性胁迫

为探讨黄河小浪底水库排沙过程中出现"流鱼"现象的原因,在水库排沙开始前和过程中以黄河鲤鱼为对象进行了生理生态观测。结果显示,相对于对照组,排沙组的黄河鲤鱼消化道充塞系数显著下降(P<0.001),消化道内容物含沙质量比率显著上升(P<0.001);肝脏总抗氧化能力显著上升(P=0.036),而脾脏总抗氧化能力显著下降(P=0.017);肝过氧化氢酶CAT活性显著上升(P=0.035);肾脏超氧化物歧化酶SOD活性显著下降(P=0.038);肝脏、脾脏丙二醛MDA含量显著下降(肝脏:P=0.039;脾脏:P=0.027);鳃丝钠钾ATP酶活性显著下降(P=0.001);血清乳酸LD含量显著上升(P=0.019);肝脏乳酸脱氢酶LDH活性显著下降(P=0.001);推测高含沙水流对黄河鲤鱼造成的急性缺氧应激是导致小浪底水库排沙过程中"流鱼"现象的主要原因之一。     

河势特征分界下的黄河滩区周边城镇生境质量与景观格局演变

在黄河流域生态保护和高质量发展战略背景下,加强对黄河滩区生境质量及其驱动机制研究对区域生物多样性保护和生态韧性提升具有重要意义。以黄河滩区沿河城镇为研究区,依据河势特征将其划分为4个河段和14个子研究区,并基于InVEST模型与3类景观格局指数分析论证不同河势特征分界下生境质量与景观格局的时空演变规律。结果表明：（1）生境质量方面,2000-2020年研究区生境质量整体呈下降趋势,各河段生境质量平均值由大到小依次为河口段、弯曲段、游荡段、过渡段;（2）景观格局方面,各河段之间景观破碎度指数波动最小,并随城镇化发展破碎化程度逐渐减弱,连接度与复杂度波动明显,且因河势特征存在差异性变化;（3）生境质量与景观格局相关性方面,多数土地景观格局指数与生境质量显著相关,但关联程度有所下降。相同地类景观格局指数在不同河段内表现出不同甚至反向的互动关系。研究表明,河势特征是黄河滩区生境质量的全局性支撑或限制因素,其作用主要体现为对黄河滩区周边城镇土地空间发展的差异化影响,该影响直接作用于紧邻黄河地带的城镇组团,并间接影响其他区域,在一定程度上左右了城镇发展主向以及土地转化、空间格局的演变规律,最终影响区域生境质量的分布格局。研究结果对黄河滩区重要生态功能区的生境保护与生态系统功能调控具有一定的理论与实践价值。     

Flood pulses drive the temporal dynamics of assemblages of aquatic insects (Heteroptera and Coleoptera) in a temperate floodplain

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Vegetation,invertebrate, and fish community response to past and current flow regulation in floodplains of the Savannah River,Southeastern USA

In 2005 and 2006, the United States Army Corps of Engineers released experimental flows to mimic natural spring flooding on the highly regulated lower Savannah River in the Southeastern US. We used vegetation, invertebrate, and fish communities to assess how past regulation and current experimental releases were affecting the ecological conditions on floodplains. The nearby Altamaha River, of similar size but retaining near-natural spring pulses, served as a reference. We did not find that past flow regulation of the Savannah River had significantly altered floodplain forest structure. However, numbers of tree seedlings in bottomland hardwood forests were higher during a year with an artificial pulse than one without. Analyses of invertebrate and fish communities suggested some limited differences in floodplain community structure between rivers, with differences being most pronounced for predaceous Dytiscidae beetles and Esox spp. fishes. Artificial re-creation of small spring flood pulses down the Savannah River in 2005 and 2006 elicited some responses from fish and invertebrates, but did not shift species assemblages towards those occurring on Altamaha River floodplains.     

The effect of anthropogenic disturbance on the hydrochemical characteristics of riparian wetlands at the Middle Ebro River (NE Spain)

In natural systems, the chemistry of floodplain waters is a function of the source of the water, which is influenced by geomorphic features of riparian wetlands. However, anthropogenic disturbances may alter both geomorphic features and the natural balance of water mixing in the floodplain. The aim of this study was to classify riparian wetlands and characterize their water characteristics in one reach of the Middle Ebro River to assess the hydrochemical functioning of the system. In order to accomplish that goal, water samples were collected at 40 sampling sites during low-water conditions and two floods of different magnitude. Moreover, geomorphic characteristics of riparian wetlands were also analyzed to interpret the results at broader spatio-temporal scales. Three group of wetlands were identified using multivariate ordination: (1) major and secondary channels highly connected to the river by surface water, containing weakly ionized water with high nitrate levels during floods; (2) secondary channels and artificial ponds located in riparian forests near the river, most of which were affected by river seepage during the examined events. This type of sites had high major ions concentrations and elevated spatial variability with respect to nutrient concentrations during floods; (3) Siltated oxbow lakes, whose hydrogeochemical features seemed to be unaffected by factors related to river fluctuations. Total dissolved solids, major ion (sulfate, chloride, sodium, calcium, magnesium, and potassium) and nutrient (nitrate, ammonium and organic nitrogen, and phosphate) depended upon the relationships between surface and subsurface water flows. Seasonal changes and geomorphic characterization indicated that a strong functional dependence of floodplain wetlands close to the main river channel is established, whereas most of the floodplain area remains disconnected from river dynamics. Moreover, the effect of nitrate-enriched agricultural runoff seems to affect water quality and hydrochemical gradients of the system. Based on our results, we propose different types of actions for the management of the Ebro River flow to ensure a more natural ecological functioning of its floodplains. Handling editor: P. Viaroli     

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Flow-induced alterations to fish assemblages, habitat and fish–habitat associations in a regulated lowland river

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Australian lungfish, <Emphasis Type="Italic">Neoceratodus forsteri</Emphasis>, threatened by a new dam

The Australian lungfish, Neoceratodus forsteri, exists as remnant natural populations in two rivers of south-east Queensland, Australia, and several translocated populations. Lungfish habitats have been impacted by agriculture and forestry, alien plants and fish and by river impoundment and regulation of flows. The species has been listed as vulnerable under Australian Commonwealth legislation. A proposal to construct Traveston Crossing Dam on the free-flowing main channel of the upper Mary River could seriously threaten the lungfish. The dam can be stopped by Commonwealth legislation if important populations of lungfish in the Mary River are likely to be significantly impacted by the new dam. This paper assembles evidence that impoundment of the Mary River and regulation of river flows are likely to decrease and fragment important lungfish populations, disrupt the breeding cycle, reduce juvenile recruitment, and isolate and decrease habitat availability/quality to such an extent that the species is likely to decline. Proposed mitigation strategies include fish transfer facilities, provision of flow releases from the dam (environmental flows) to sustain lungfish habitat and breeding downstream, and translocation of hatchery-reared juvenile lungfish into suitable natural habitats. These mitigation efforts may not be sufficient to secure the genetic diversity and long-term viability of lungfish populations in the Mary River.     

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Flood intensity was a main factor determining access to the riparian/floodplain ecotonal resources of the upper Parana River, Brazil, and in consequence determining yield of the dominant trophic groups, which are fish feeding on flooded grasslands and on riparian fruits and leaves. Prey and predator density both declined in years of low floods, and predators did not recover until the next year of high flood, more slowly than in the case prey fish, most probably due to differences in life cycle length. The life cycle of one of the most important species, Curimba (Prochilodus lineatus — Characidae) depends on access to the floodplain lagoons and return to the reservoir after maturation for intensive growth. The riparian/floodplain habitat complexity and connectivity has great significance for fish community dynamics and fisheries yield, and may serve a reason to create a national park in the last floodplain section of the upper Parana River.     

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Wetlands Ecology and Management - The introduction of Common Carp (Cyprinus carpio) into North American waterways has led to widespread alteration of aquatic ecosystems. Control of this invader has...