塔里木河下游阿拉干断面胡杨枝下高对应急输水的响应

根据近5 a来对塔里木河下游阿拉干断面胡杨林(Populus euphratica Oliv.)的监测数据和不同离河距离的地下水位监测信息,结合"面"上宏观调查与"点"上典型研究,集中对100 hm2长期监测样方内的4 499棵胡杨树进行了详细的调查,将胡杨个体实测数据和卫星影像信息进行对比,分析了塔里木河下游胡杨枝下高对应急生态输水的响应.结果显示,塔里木河下游的胡杨具有伴河生长的特性,不同等级枝下高的胡杨都主要分布在距离河道200 m的范围,且其分布都与离河道距离呈显著负相关关系;应急输水后,不同离河距离的胡杨枝下高都有不同程度的下降,河道附近100 m的范围内下降幅度最大,达到了0.36 m,枝下高的下降主要是由于胡杨茎部和基部萌生新枝所引起的,说明应急输水对于胡杨的自然更新产生了积极的影响.     

塔里木河下游应急输水前后胡杨年轮生长差异

1972年塔里木河下游大西海子水库建成,下游365km河道彻底断流。为拯救沿河植被,2000年5月启动了塔里木河下游应急输水工程,迄今已经完成了7次应急输水。文章通过对塔里木河中游英巴扎和下游输水河畔英苏、喀尔达依、阿拉干断面胡杨(Populus euphratica)一级枝年轮取样调查,运用统计方法比较不同离河距离输水前后胡杨生长量差异的大小,分析了下游应急输水河畔胡杨种群对输水的响应。结果表明:1)英苏断面和喀尔达依断面在离河0~1000m输水前后胡杨生长量差异极显著。阿拉干断面在离河0~300m输水前后胡杨生长量差异极显著,离河300~700m生长量差异显著,700~1000m生长量差异不显著。由输水前后胡杨年轮生长量均值差可得,同一断面不同离河距胡杨年均生长量随离河距增大而降低。2)输水后下游3个调查断面在离河0~300m胡杨生长量增长由大到小顺序为:喀尔达依>英苏>阿拉干;离河300~700m由大到小顺序为:喀尔达依>阿拉干>英苏。3)以中游胡杨同年生长量作为参照对下游胡杨生长量进行相关比较的结果表明:应急输水前输水河畔各离河距离胡杨生长量均小于中游参照河段的生长量。应急输水后,输水河畔离河0~300m生长量已超过中游的生长量;离河300~700m输水河畔的生长量接近中游生长量;离河700~1000m生长量小于中游参照河段生长量,应急输水明显地促进了胡杨生长。     

塔里木河下游生态输水过程中荒漠河岸林活力恢复监测

根据近5年来对塔里木河下游荒漠河岸林植被的监测数据,分析了生态输水后植物活力的恢复状况.结果显示:应急生态输水增加了塔里木河下游的生物多样性,使原本面临死亡的荒漠河岸植被重新复活,而且不同程度上促进了胡杨群落的自然更新;在近河道50 m的范围内均出现了少量的胡杨、柽柳实生苗,并且在离河道150 m的范围内已经有相当数量的胡杨次生苗,在离河道400 m范围内大约有25%的胡杨均有不同程度的基部新枝萌蘖.通过生态输水后地下水位的逐步抬升,河道两岸的低阶地发育着一定面积的草甸植被,形成了由胡杨、柽柳和草本植物所组成的干旱区非地带性河岸稀疏植被群落,说明应急生态输水对于胡杨为建群种的荒漠河岸林植被的恢复和自然更新产生了积极的影响.     

新疆塔里木河下游生态输水对胡杨叶片MDA含量的影响

结合塔里木河下游生态输水后地下水位变化的监测和胡杨叶片中能够指示环境变化的丙二醛(MDA)含量的测定，对塔里木河下游地下水位变化与胡杨叶片中MDA积累变化关系进行了分析．结果表明，胡杨叶片MDA含量随着地下水位的下降、干旱胁迫程度的增强呈现出明显增加态势，与地下水位变化存在密切关系．结合野外样地调查分析得出：地下水位埋深在4．42m时，胡杨生长已受到水分胁迫；在5．78-6．46m之间，胡杨受到中度水分胁迫，胡杨的生长发育将受到明显的抑制；而在8．89～9．74m之间，胡杨受到重度水分胁迫，将面临着死亡的威胁．图6参22     

塔里木河下游荒漠植物群落物种多样性及其结构特征分析

以29块植物群落调查样地资料为基础,采用物种多样性指数、丰富度和均匀度由高到低指数对塔里木河下游植物群落的物种多样性及群落结构进行分析。结果表明,研究区共有植物10科14属,出现频率居于前3位的植物依次为柽柳、黑果枸杞和胡杨;重要值以胡杨为最大（0．384）,其次为柽柳（0．230）,盐生草为最小（0．002）;优势建群植物胡杨主要分布在与河道垂直距离500m范围内。沿河道从英苏至阿拉干断面,地下水位逐渐下降,物种多样性总体呈下降趋势,群落结构由乔木-灌木-草本转为以乔木-灌木为主;随与河道垂直距离增加,群落密度和盖度均呈现先增加后减少的变化趋势,植物群落结构由乔木-灌木、乔木-灌木-草本逐渐演变为灌木-草本或单一的灌木结构。     

塔里木河下游植物群落结构特征分析

对塔里木河下游经30a断流后的应急输水河畔植被进行外业调查,分析了调查区植物群落的种类组成、垂直结构、密度结构以及优势种群的格局分布,旨在了解输水后研究区植物群落在结构特征方面恢复程度。结果表明:调查样地内有植物13种,其中胡杨(Populus euphratica)、柽柳(Tamarix)、黑果枸杞(Lycium ruthenicum)、花花柴(Karelinia caspica)和疏叶骆驼刺(Alhagi sparsifolia)为优势种。不同地下水条件物种的重要值不同,表现在不同离河距离具有不同的物种组成结构,随地下水埋深不同植物群落由以胡杨和胀果甘草为主到以柽柳、黑果枸杞、花花柴和疏叶骆驼刺等抗旱耐盐碱植物为主。乔木层密度随着离河距离加大而减小,灌木层和草本层密度随离河距离加大呈先增加后减小的趋势。群落垂直结构随离河距离加大由乔-灌-草3层逐渐转变为灌-草2层,随离河距离加大趋于简单。优势种群胡杨在离河300m以内呈聚集分布,聚集强度随离河距加大而增强;柽柳灌丛在离河50m呈均匀分布,离河150m以外呈聚集分布,但离河750m段有向随机分布发展趋势。植物群落结构特征在不同的离河距离具有差异,说明经过输水下游植物群落的恢复在结构特征方面有响应,为区域生态治理和保护提供科学依据。     

叶尔羌河下游河岸胡杨种群长势与植物多样性对淹灌的响应评估

通过定量研究叶尔羌河下游河岸胡杨(Populus euphratica)种群长势与植物多样性对淹灌的响应,为优化叶尔羌河流域水资源管理与生态保护实践提供理论依据。于2016—2018年3次调查叶尔羌河下游植被数据,采用Pielou指数、Shannon-Wiener指数、Simpson指数和重要值等指标分析植被对淹灌的响应。结果表明,淹灌2 a后,叶尔羌河下游河岸胡杨Simpson指数、Shannon-Wiener指数和Pielou指数分别增加124. 8%、119. 6%和246. 9%,且新增喜湿和一年生草本植物等12种,植被盖度为42. 5%,增幅达112. 5%。研究区胡杨林为中老龄,胡杨长势没有恶化,中等级以上胡杨林增加3. 9%,胡杨平均枝下高下降7. 7%。随着距生态闸口距离的增加,植物密度和多样性均有减小趋势,但距生态闸口距离450 m处植物多样性和植物密度较高,与150、300和600 m处差异显著(P0. 05),在150和300 m处优势种为苦豆子和芦苇等一年生草本和喜湿植物,在450 m范围外优势种则为胡杨、柽柳和耐旱多年生草本。2 a的淹灌工程遏制了胡杨林退化趋势,植物多样性和植被盖度显著提高,同时荒漠河岸林植物群落在450 m范围内更新能力得到增强,生物多样性得到保护。为维持目前生态好转趋势,应继续实施淹灌工程。     

黑河下游胡杨群落多样性沿河岸距离的变化特征

胡杨(PopuluseuphraticaOliv.)是荒漠河岸林的主要建群种之一,对维持荒漠河岸生态系统稳定和抑制荒漠化有着重要意义。为科学认识极端干旱荒漠河岸地带胡杨群落结构、多样性特征沿河岸距离的变化规律,选择黑河下游荒漠河岸地带自然分布的胡杨林作为观测样地,沿垂直河岸方向上设置9个采样点,分析沿河梯度上胡杨群落物种组成、结构、植物区系与多样性特征。结果表明:在沿河梯度上,共有物种7科9属9种,物种多样性低,胡杨在群落中占绝对优势(重要值为0.61—0.90),是群落优势建群种。植物区系贫乏,单种科和单种属占比高,具有明显温带属性,且与古地中海成分地理联系密切。随着沿河岸距离的增加,植物群落结构由乔-灌-草向乔-草类型过渡,植物群落盖度呈先上升后下降的显著变化趋势,在距河650 m处达到最大,为74.33%,灌木层盖度总体上低于乔木层和草本层。胡杨群落多样性指数偏低,Patrick指数、Simpson指数、Shannon-Wiener指数和Pielou指数最大值分别为7、0.66、1.31、0.81。α多样性指数随沿河岸距离的增加呈先上升后下降变化趋势,在距河650—800 m之间达到峰值,其中Pielou指数变化不显著。Cody指数在距河650—800 m和800—950m之间出现较大值,而S?rensen指数较小,表明该区域β多样性最大,胡杨群落样地间异质性程度高。在黑河下游荒漠河地带,土壤水盐变化限制和调控着草本植物的生长和分布,对胡杨林群落多样性产生重要的影响。研究结果有助于认识该地区沿河胡杨群落结构特征及其多样性格局,也将为荒漠河岸胡杨林植物资源的管理和恢复提供科学参考。     

黑河下游荒漠河岸地带土壤水盐和养分的空间分布特征

探讨干旱区内陆河流域荒漠河岸地带土壤水盐和养分的变化特征,对荒漠河岸生态系统的保育和恢复具有重要指导意义。以黑河下游垂直于河道的乌兰图格嘎渣监测断面为研究对象,通过野外采样调查,分析距河道4 500 m范围内荒漠河岸地带土壤水盐和养分在沿河梯度上的空间分布特征。结果表明:在0-50 cm土层,土壤含水量、土壤容重、土壤pH、土壤电导率、土壤总碳、土壤总氮、土壤速效磷和土壤速效钾在沿河梯度上表现出显著的差异性。随着沿河距离增加,土壤含水量大体表现为下降的变化趋势,在300 m和2 950 m处达到峰值,均值分别为26.57%和8.72%;而土壤容重呈相反的变化趋势,在4 500m处最高,均值为1.73g·cm~(-3)。土壤pH值随着沿河距离的增加呈凹型变化趋势,较大值出现在距河岸300-800 m和4 000-4 500 m处,均值分别为9.21-9.24和8.7-9.18,而土壤电导率则大体呈凸型变化趋势,较大值出现在距河岸2 200-3 200 m,均值为5.69~(-1)4.92 ms·cm~(-1),盐分表聚现象严重。随着沿河距离增加,土壤总碳、土壤总氮、土壤速效磷和土壤速效钾含量基本都表现出显著下降的变化趋势,在4 000-4 500 m处值最小,均值分别为5.71、0.11、2.81和73.76mg·kg~(-1),土壤养分(0-10cm)波动最为明显,由表层向下呈逐渐降低趋势。在沿河梯度上,生态输水对近河岸地带土壤的演变机制和恢复趋势有明显的促进作用,随沿河距离增加影响力渐小。在荒漠河岸生态系统恢复中,可在垂直河岸梯度上延长生态输水距离,促进地下水水位回升,有利于改善土壤结构和理化属性。     

胡杨年轮记录的塔里木河下游54年来区域水环境历史变迁

通过胡杨（Populus euphratica Oliv．）树木年轮宽度的分析,建立了塔里木河下游大西海子（A）、阿克墩（B）、亚合甫马汗（c）、英苏（D）、阿布达勒（E）、喀尔达依（F）、吐格买莱（G）、阿拉干（H）、依干不及麻（I）和考干（J）10个采样区过去54a来的STD、RES和ARS年表,并借助RES年表,采用年代际变化分析和突变检验,反演了塔里木河下游54a年来区域水环境状况变迁时空格局。结果表明：①下游10个样区54a来区域水环境状况具有多样性和复杂性,并不完全表现为距离下游上段（大西海子水库）越近其水环境状况就越好,区域水环境状况总体变异程度由低到高排序为A、G、C、H、E、D、I、B、F、J,也反映了下游10个样区生态退化程度的差异;②下游54a来区域水环境状况最好时期出现在20世纪60年代和21世纪初,大部分区域最差时期主要集中在20世纪90年代,是下游地区长达30a断流水环境变干累积效应的体现;③下游10个样区区域水环境变化具有明显的突变时间,突变出现时间相对水文事件年代具有滞后性。胡杨年轮记录的塔里木河下游54a来区域水环境时空变迁格局对下游生态退化的历史认识具有重要意义。     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

豪猪消化系统的解剖研究

为了了解豪猪的消化生理,为豪猪的人工饲养技术研究提供基础依据,以达到高效饲养豪猪的目的,笔者对豪猪的消化器官进行了系统解剖研究.结果表明:豪猪的胃为单室胃.盲肠很发达,这与其能够消化植物纤维有关.豪猪肝脏很发达,其重量为402 g,是其体重的4.59%,肝脏分叶多而明显.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.     

Mining of the forest and the time path of the price of timber

The paper analyzes the effect of transportation (site specific) costs and the effect of mining (depletion) of the forest on the time path of the price and of the net price of timber in two forestry models. The models differ in that one has zero costs and the other has positive costs. The analyses yield the standard mining theory results for certain cases. They also yield extentions of these results for cases with growth of the harvested trees and/or regeneration on the harvested land. The paper concludes, as one would expect, that the theory of the mine is useful in analyzing the time path of the price of timber.     

刍议医院资产管理的现状及其对策

医院的固定资产和流动资产是医院赖以生存和发展的基础,是一项非经营性国有资产．目前公立医院固定资产、流动资产管理现状不容乐观,针对这种状况,首先分析问题形成的原因,然后提出管理的措施或建议,从而使资产管理工作规范化、制度化、科学化,使有限的卫生资源发挥出最大的社会效益和经济效益．参3．     

Stimulation of fat-body production in the polyps of the coralPocillopora damicornis by the presence of mutualistic crabs of the genusTrapezia

A mutualism exists between the xanthid crabs of the genusTrapezia and their host corals,Pocillopora damicornis. It has previously been established that these obligate coral residents benefit the coral hosts by defending them against echinoderm predators and by increasing the survival of polyps located deep between the coral branches. In turn, the corals apparently benefit the crabs by producing lipid-filled structures on which the trapezid crabs feed; these fat bodies may contain some of the lipid which in previous studies of coral metabolism has been termed excess. It was determined by experiments conducted at the Hawaii Institute of Marine Biology that the presence of crabs in colonies ofP. damicornis stimulates the polyps to produce the lipid-filled fat bodies; removal of crabs causes corals to cease producing fat bodies. A structure very similar to the fat bodies ofP. damicornis has been reported inAcropora durvillei. Both of these coral genera ordinarily possess xanthid-crab mutualists. This association between branching corals and crustaceans may have evolved because corals of these genera provide shelter among their branches and because these shallow-water corals are evidently capable of releasing lipid which is excess to the corals' metabolic needs, but which can be utilized by the crabs.     

Splitting the tail of the displacement kernel shows the unimportance of kurtosis

Animals disperse in space through different movement behaviors, resulting in different displacement distances. This is often described with a displacement kernel where the long-distance dispersers are within the tail of the kernel. A displacement with a large proportion of long-distance dispersers may have impact on different aspects of spatial ecology such as invasion speed, population persistence, and distribution. It is, however, unclear whether the kurtosis of the kernel plays a major role since a fatter tail also influences the variance of the kernel. We modeled displacement in landscapes with different amounts and configurations of habitats and handled kurtosis and variance separately to study how these affected population distribution and transition time. We conclude that kurtosis is not important for any of these aspects of spatial ecology. The variance of the kernel, on the other hand, was of great importance to both population distribution and transition time. We argue that separating variance and kurtosis can cast new light on the way in which long-distance dispersers are important in ecological processes. Consequences for empirical studies are discussed.     

Hypothesis Concerning the Causes of the Disappearance of Boreal Toads from the Mountains of Colorado

Recent reports of world-wide declines and extinctions of amphibian populations have raised questions about the relation of environmental change to the demise of certain amphibian species. Between 1974 and 1982, 11 populations of boreal toads ( Bufo boreas boreas ) in the West Elk Mountains of Colorado totally disappeared. The apparent cause of extinction of these toads was infection with the bacteria Aeromonas hydrophila . In this paper, the presence of disease in declining populations of these toads is used in conjunction with a variety of data from the literature to formulate a working hypothesis for explaining the cause of the decline of this species, and perhaps others: