封育对高寒草甸植物群落构成及生态位特征的影响

封育是天然草地管理的一种有效措施,利于草地生产力提高和退化草地恢复。该研究通过对青藏高原高寒草甸放牧和封育草地物种多样性、植被构成、植物种生态位特征、草地演替度等分析,解析高寒草甸植物种间关系及草地演替方向。结果表明:(1)封育显著降低了草地群落植物物种数以及α和β多样性指数,显著增加了草地1年生植物种数、地面芽植物种数和地上生物量。(2)放牧草地地上生物量以莎草科(59.7%)和禾本科(23.9%)为主,封育草地地上生物量以禾本科(85.0%)为主;放牧草地优势种为矮嵩草(Kobresia humilis)和线叶嵩草(K.capillifolia),封育草地优势种为垂穗披碱草(Elymus nutans)和早熟禾(Poasp.)。(3)放牧和封育草地的群落植物种重要值均与各自的生态位宽度变化规律一致。(4)草地植物种间竞争主要发生在不同科属植物种之间,封育增加了群落植物种整体生态位重叠值和植物种间竞争。(5)草地群落演替度为封育地放牧地,封育群落处于较稳定状态。研究认为,封育促进了高寒草甸由莎草+杂类草群落向禾草+杂类草群落演替。     

西藏那曲地区高寒草地地下生物量

矮嵩草草甸、藏北嵩草草甸及紫花针茅草原是那曲地区主要的草地类型,通过对其地下生物量的分布特征、地下/地上生物量的关系及其对土壤环境影响的研究发现:(1)这三类植物群落的地下生物量表现为总的T字形趋势下的锯齿状分布,主要分布在0~10cm的草皮层中,而且不同的退化草地,其地下的生物量也不同;(2)各群落的地下生物量和地上生物量密切相关,相关性均呈显著正相关。地下/地上生物量的比值越大,地上生物量就越高。地上生物量的变化不大,而地下生物量变化显著;(3)在高山草甸土中,矮嵩草草甸的地下生物量和土壤的有机质,全N,碱解N的含量及土壤的容重呈相关关系,而与其他的土壤因子相关性不显著。(4)各群落的地下生物量的垂直分布特征及与土壤环境的关系是植物长期适宜高寒生境条件的结果和反映。     

围封对退化矮嵩草草甸群落结构和主要种群空间分布格局的影响

通过研究围栏封育1年后中度退化的矮嵩草草甸(夏季牧场)群落结构的变化,探讨主要植物种群在小尺度(50 cm×50 cm)上的空间分布格局,并从生活史特征和生态适应对策等角度探讨产生和维持这些格局的机理。结果表明,围封1年显著降低了群落中主要种群矮嵩草(Kobresia humilis)、高山唐松草(Thalictrum alpinum)和雪白委陵菜(Potentilla nivea)的重要值,而增加了线叶龙胆(Gentiana farreri)的重要值;显著增加了群落的地上生物量和总生物量,但对地下生物量和群落多样性的影响不显著。围封使退化矮嵩草草甸主要种群矮嵩草、高山唐松草、珠芽蓼(Polygonum viviparum)、线叶嵩草(Kobresia capillifolia)和金露梅(Potentilla fruticosa)等空间分布格局从放牧后的随机分布向聚集分布发展,而雪白委陵菜、重齿风毛菊(S.katochaeteMaxim)、矮火绒草(Leonto-podium nanum)和美丽风毛菊(Saussurea pulchra)等种群的空间分布格局没有发生改变;但黑褐苔草(Carex atro-fusca)的空间格局从放牧后的聚集分布转向随机分布。因此,退化的矮嵩草草甸在围封的初始阶段,由于避免了家畜的选择性采食及其践踏作用,首先可能是使主要种群的空间分布格局有从随机分布向聚集分布变化的趋势,从而使小尺度的种间隔离来降低种间的竞争强度,从而改变了不同物种对资源和空间的竞争能力,进而推动群落物种组成和结构的恢复演替。     

青藏高原北部多年冻土区草地植物多样性

研究了青藏高原北部多年冻土区草地群落植物多样性的特征。研究表明 :草地群落间丰富度指数差异不显著 ,均匀度指数和多样性指数差异显著 (P<0 .0 5 )。均匀度指数表现为高山嵩草 (Kobresia pygmaea)草甸 <紫花针茅 (Stipa purpurea)草原 <矮嵩草 (K.humilis)草甸 <青藏苔草 (Carex moorcroftii)草甸 ,多样性指数表现为高山嵩草草甸 <矮嵩草草甸 <紫花针茅草原<青藏苔草草甸。修路时破坏的矮嵩草草甸在次生恢复过程中 ,离公路 10 0 m处群落的丰富度指数 ,均匀度指数和多样性指数大于原生群落 ,而原生群落的多样性又大于 30 m和 5 0 m处群落的多样性。地上草地群落植物多样性伴随地下冻土退化过程表现为 ,以 1m2样方统计时 ,各个演替群落间的丰富度指数差异不显著 ,而以 10 0 m2样条统计时 ,高寒草甸和草原化草甸的丰富度指数显著大于沼泽草甸和稀疏草原 (P<0 .0 5 ) ,但均匀度和多样性指数在两种统计面积时均表现为先增加后下降的变化趋势。     

高原鼠兔有效洞穴密度对高山嵩草群落及其主要种群空间分布特征的影响

高原鼠兔(Ochotona curzoniae)有效洞穴密度变化会引发高山嵩草(Kobresia pygmaea)草甸植物群落及其种群分布格局发生变化。采用野外调查法研究了高原鼠兔有效洞穴密度对高山嵩草群落特征及其主要种群分布格局的影响。结果表明:随高原鼠兔有效洞穴密度增加,高山嵩草草甸植物群落的优势种没发生明显变化,部分伴生种发生更替;高度、盖度、多样性指数和均匀度指数呈现降低态势;地上生物量和丰富度指数变化不明显;高山嵩草和矮火绒草(Leontopodium nanum)种群的盖度、密度以及生物量均呈现降低态势,而达乌里秦艽(Gentiana dahurica)和小花草玉梅(Anemone rivularis var.flore-minors)种群的盖度、密度和生物量呈增加趋势。高山嵩草和矮火绒草的种群分布格局从8个/625m2和14个/625m2的聚集分布分别变为34个/625m2时的均匀分布和随机分布,达乌里秦艽和小花草玉梅种群从8个/625m2和14个/625m2的随机分布变为23个/625m2和34个/625m2时的聚集分布,这说明高原鼠兔有效洞穴密度变化改变了高山嵩草群落的特征和主要植物种群的空间分布格局,而对应群落特征和种群分布格局改变的有效洞穴密度为14个/625m2和23个/625m2。     

青藏高原高寒草甸植物群落物种组成和生物量沿环境梯度的变化

生物多样性与生态系统功能的关系及其机制是生态学领域的重大科学问题. 人们越来越关注环境因子对多样性-生产力关系的影响. 植物群落组成、物种丰富度、物种特征、生物量的分布结构和植物枯枝落叶对高寒草甸物种多样性和生产力有着重要的影响. 因此, 我们利用2001~2004年中国科学院海北生态系统定位站高寒草甸群落的实测资料, 研究了不同环境梯度(土壤含水量和营养)下, 植物群落生物量, 物种丰富度及组成的变化. 结果表明, 植物群落物种组成的不同反应在生物量的分布上, 以藏嵩草为优势种的藏嵩草沼泽化草甸群落总生物量(地上、地下)最高(13196.96±719.69 g/m²), 次之是以杂类草和莎草科为主的小嵩草草甸(2869.58±147.52 g/m₂), 以禾本科和杂类草为主的矮嵩草草甸最低(2153.08±141.95 g/m²). 藏嵩草沼泽化草甸中, 草本植物枯枝落叶显著高于小嵩草、矮嵩草草甸, 土壤含水量对草本植物枯枝落叶有较大的影响. 不同类型草甸群落中, 地上生物量与土壤有机质、全氮和群落盖度之间均呈显著正相关(P < 0.05); 藏嵩草沼泽化草甸中, 总生物量与物种丰富度呈负相关(r_s = -0.907, P < 0.05)、地下生物量与土壤含水量呈正相关(r_s = -0.900, P < 0.05); 而在小嵩草和矮嵩草草甸中它们之间均没有达到显著水平, 说明不同类型高寒草甸群落生产力除受物种多样性、功能群内物种密度和均匀度的影响, 同时也受物种本身特征和外部环境资源的影响. 不同类型草甸群落生物量的分布与土壤含水量和土壤养分的变化相一致.     

拉鲁湿地主要植物群落结构及物种多样性

2002年6~9月对拉鲁湿地植物种类、群落结构、生物量以及物种多样性进行了调查研究.结果表明:(1)拉鲁湿地共有植物30科52属85种,主要有芦苇[Phragmites australis(Cav.)Trin.ex Steud.](A)、尼伯尔酸模(RumexnepalensisSpreng)(B)、水葱(Scirpus validusVahl)(C)、穗状狐尾藻(MyriophyllumspicatumL.)(D)、灯芯草(Juncus effususL.)(E)、针叶苔草(CarexonoeiFranch.et Sav.)和黑褐苔草(CarexatrofuscaSchkuhr)(F)、藏北嵩草(KobresialittledaleiC.B.Clarke)(G)、藏蓟[Cirsiumlanatum(Roxb.ex Willd.)Spreng.](H)等8个主要植物群落.(2)在8个主要植物群落中,嵩草群落所含物种数最多,为44种,穗状狐尾藻群落最少,仅8种;芦苇群落生物量最高,为124.5~1 027.0 g/m2,藏蓟群落生物量最低,为124.5~220.5 g/m2;优势种芦苇的生物量最高,为183.5~660.0 g/m2,藏蓟生物量最低,为43.1~76.3 g/m2.(3)各群落的垂直结构特点是:芦苇群落、水葱群落、穗状狐尾藻群落具有挺水层、浮叶层和沉水层,其他群落只具有可分为高、低两层的草本层.(4)在各群落的相似性方面,嵩草群落与藏蓟群落、水葱群落与芦苇群落和尼伯尔酸模群落的相似性要明显高于其他群落,其Jaccard系数分别为0.549 0、0.538 5、0.500 0;芦苇群落、尼伯尔酸模群落、水葱群落、穗状狐尾藻群落与藏蓟群落以及芦苇群落、穗状狐尾藻群落与嵩草群落在建群种上没有相似之处,Jaccard系数为0.     

洞庭湖典型湿地植被群落土壤微生物特征

以洞庭湖湿地3种典型植被(虉草、苔草、芦苇)为对象,研究了不同植被下土壤微生物生物量和微生物呼吸等特征,并对其主要影响因子进行了分析.结果表明:微生物生物量碳、氮和微生物呼吸以虉草群落最高,苔草群落次之,芦苇群落最低,微生物碳熵变化趋势为虉草群落＞苔草群落＞芦苇群落,微生物呼吸熵具有与微生物碳熵相反的变化趋势.相关分析表明:土壤含水量、容重和有机质是影响土壤微生物特征变化的重要因子,同时,土壤pH和土壤总氮与土壤微生物生物量碳、微生物生物量氮、微生物呼吸等也有较强的关联性.     

季节性雪被对青藏高原东缘高寒草甸2种优势植物碳、氮积累和分配的影响

依据2006~2008冬季的自然雪被分布状况,在青藏高原东缘的高寒草甸中设置3条样带（即深雪、中雪和浅雪）。在2009年的生长季,在3个雪梯度样带中,分别测定了2种优势植物圆穗蓼（Polygonum macrophyllum）和黑褐穗苔草（Carex atrofusca subsp. Minor）生物量和碳氮营养积累及分配的动态特征。结果表明,深雪能够促进圆穗蓼和黑褐穗苔草生物量和碳氮养分的积累,可能使它们产生的凋落物数量更多且质量更好。深雪更有利于圆穗蓼（非禾本科草本植物）根系生物量、碳氮养分的积累;深雪不仅同时促进黑褐穗苔草（禾本科植物）地上部分和根系生物量、碳氮积累,而且还使其种子产量增加和质量提高,潜在地增强了黑褐穗苔草种子的繁殖能力,可能使得黑褐穗苔草的种间竞争能力增强。可以预见,未来季节性雪被的变化,必定会引起青藏高原东缘高寒草甸的初级生物量及其结构、植物群落物种组成等均发生相应变化。     

玛曲高寒草甸沙化过程中群落结构与植物多样性

针对玛曲高寒草甸沙质荒漠化和水土流失日趋严重的问题,采用群落样方调查的方法,研究了潜在、轻度、中度和重度4种典型高寒沙化草甸的植被结构特征和α多样性与β多样性变化规律。结果表明:随着沙化程度的加剧,1)群落植被盖度持续下降(分别为99.216%,80.078%,49.895%,36.398%)、物种数逐渐减少(分别为53,32,14,13)、群落结构趋向简单(重要值大于1的物种分别有28,16,10,8种),典型高寒草甸优势种和伴生种逐渐退出群落,而适应沙质荒漠的物种逐渐占据群落中的优势地位,玛曲高寒草甸生态系统有向高寒沙质荒漠生态系统转化的趋势,群落以青藏苔草+高山早熟禾群落→青藏苔草+防风+高山嵩草群落→高山嵩草+防风+青藏苔草群落→毛穗赖草+藏虫实+青藏苔草+防风群落的方向演替;2)群落丰富度和植物多样性指数均呈下降趋势,差异显著;均匀度指数先增加后减小,在轻度沙化草甸达到最大,但差异不显著;而群落优势度逐渐增加,在中度沙化草甸增加极显著;3)潜在沙化草甸与沙化草甸之间的Whittaker指数差异极显著,中度沙化草甸与重度沙化草甸之间差异显著,而轻度沙化草甸与中度沙化草甸之间差异不显著。4)潜在沙化草甸与3种沙化草甸和轻度沙化草甸与重度沙化草甸之间群落相异性系数较高(0.705—0.937),群落共有度指数较低(0.034—0.173),而重度沙化草甸与中度沙化草甸、轻度沙化草甸与中度沙化草甸之间群落相异性系数相对较低(0.545—0.553),群落共有度指数相对较高(0.293—0.303)。以上分析表明,玛曲高寒草甸在沙化过程中存在轻度沙化和重度沙化两个关键过程,因此对潜在沙化草甸应采取封育、禁牧、轮牧、抚育等科学管护措施,而对沙化草甸应采取草皮移植、补播、施肥等植被快速恢复措施和流沙治理措施进行生态修复,防止草甸沙化的加剧和蔓延。     

评世界保护联盟新的物种受威胁分类系统草案

为了进一步了解物种受威胁的情况和发展,以加强物种保护工作,世界保护联盟制定了一个新的物种受威胁分类系统草案,把物种受威胁的程度分为９个级别,即绝灭种、野生状态下的绝灭种、极危种、濒危种、渐危种、敏感种、安全的／危险性小的种、不充分了解的种和未估价的种。本文对这个分类系统草案作了简略的评介。     

Recommendations for Assessing the Effectiveness of Surrogate Species Approaches

Surrogate species approaches, including flagship, focal, keystone, indicator, and umbrella, are considered an effective means of conservation planning. For conservation biologists to apply surrogates with confidence, they must have some idea of the effectiveness of surrogates for the circumstances in which they will be applied. We reviewed tests of the effectiveness of surrogate species planning to see if research supports the development of generalized rules for (1) determining when and where surrogate species are an effective conservation tool and (2) how surrogate species should be selected such that the resulting conservation plan will effectively protect biodiversity or achieve other conservation goals. The context and methods of published studies were so diverse that we could not draw general conclusions about the spatial or temporal scales, or ecosystems or taxonomic groups for which surrogate species approaches will succeed. The science of surrogate species can progress by (1) establishing methods to compare diverse measures of effectiveness; (2) taking advantage of data-rich regions to examine the potential effectiveness of surrogate approaches; (3) incorporating spatial scale as an explanatory variable; (4) evaluating surrogate species approaches at broader temporal scales; (5) seeking patterns that will lead to hypothesis driven research; and (6) monitoring surrogate species and their target species.     

Extensive contiguous north–south range expansion of the original population of an invasive lizard in Florida

Florida has one of the two worst non-indigenous invasive species problems in the United States, and all such species are considered by statute to be a potential ecological problem. Unfortunately, little information is available about most of Florida's invasive species. Here, we provide information on range expansion of a population of one of the lesser-known species. The Palm Beach County, Florida, population of the northern curly-tailed lizard, Leiocephalus carinatus armouri, was examined for north–south expansion of its previously documented range. Observations were conducted as contiguous expansion outward from the previously known range. We found a substantial contiguous range expansion by a minimum of 46.3 km to the south and 34.1 km to the north. This species appears to be closely associated with coastal habitat degradation in the form of human infrastructure, especially ageing pavement, sea walls, buildings, and bridge bases.     

红雪茶基源种的鉴定及资源分布

本研究通过对红雪茶基源种进行考证,并结合品种鉴定及野外生态调查,结果表明,红雪茶的基源种应为金丝刷（Lethariella cladonioides）和金丝带（L.zahlbruckneri）,在这两个种群内,存在化学多态现象。市售的“红雪茶”主要由这两个种的四个化学宗所组成。红雪茶的分布中心主要在藏东南,滇西北及川西地区,目前红雪茶的资源已经受到了极大的破坏,日渐濒危。为加强对野生红雪茶资源的有效保护,提出了开展红雪茶种质资源保护的建议。     

列入《濒危野生动植物物种国际贸易公约》附录的物种的新标准

ＣＩＴＥＳ（濒危野生动植物国际贸易公约）是一个通过控制贸易的方法来维护物种生存及其持续利用的国际法规,其附录中所列的物种是重点管理的对象,主要根据现有的Ｂｅｒｎｅ标准来确定。但是,长期的实践证明,它已不能满足实际的需要。１９９２年６月ＣＩＴＥＳ常务委员会要求世界保护联盟协助制定一个简明、实用、科学和客观的新标准,本文对此作一简介和讨论。     

Increasing numbers of bird species result from taxonomic progress,not taxonomic inflation

The impact and significance of modern taxonomy on other fields in biology have been subjects of much debate. It has been proposed that increasing numbers of vertebrate species are largely owing to ‘taxonomic inflation’. According to this hypothesis, newly recognized species result from reinterpretations of species limits based on phylogenetic species concepts (PSCs) rather than from new discoveries. Here, I examine 747 proposals to change the taxonomic rank of birds in the period 1950–2007. The trend to recognize more species of birds started at least two decades before the introduction of PSCs. Most (84.6%) newly recognized species were supported by new taxonomic data. Proposals to recognize more species resulted from application of all six major taxonomic criteria. Many newly recognized species (63.4%) were not based exclusively on PSC-based criteria (diagnosability, monophyly and exclusive coalescence of gene trees). Therefore, this study finds no empirical support for the idea that the increase in species is primarily epistemological rather than data-driven. This study shows that previous claims about the causes and effects of taxonomic inflation lack empirical support. I argue that a more appropriate term for the increase in species is ‘taxonomic progress’.     

种间作用对物种分布模拟的影响及建模方法

物种分布模型(SDMs)通过量化物种分布和环境变量之间的关系,并将其外推到未知的景观单元,模拟、预测地理空间中生物的潜在分布,是生态学、生物地理学、保护生物学等研究领域的重要工具.然而,目前物种分布模型主要采用非生物因素作为预测变量,由于数据量化和建模表达困难,生物因素特别是种间作用在物种分布模型中常被忽略,将种间作用...     

Species pool size and invasibility of island communities: a null model of sampling effects

The success of alien species on oceanic islands is considered to be one of the classic observed patterns in ecology. Explanations for this pattern are based on lower species richness on islands and the lower resistance of species‐poor communities to invaders, but this argument needs re‐examination. The important difference between islands and mainland is in the size of species pools, not in local species richness; invasibility of islands should therefore be addressed in terms of differences in species pools. Here I examine whether differences in species pools can affect invasibility in a lottery model with pools of identical native and exotic species. While in a neutral model with all species identical, invasibility does not depend on the species pool, a model with non‐zero variation in population growth rates predicts higher invasibility of communities of smaller pools. This is because of species sampling; drawing species from larger pools increases the probability that an assemblage will include fast growing species. Such assemblages are more likely to exclude random invaders. This constitutes a mechanism through which smaller species pools (such as those of isolated islands) can directly underlie differences in invasibility.     

Biotransformation of acyclic monoterpenoids by Debaryomyces sp., Kluyveromyces sp., and Pichia sp. strains of environmental origin

Sixty yeast strains, which belong to 32 species of the genera Debaryomyces, Kluyveromyces, and Pichia, and which were isolated from plant-, soil- or insect-associated habitats, were screened for their ability to biotransform the acyclic monoterpenes geraniol and nerol. The aptitude to convert both compounds (from 2.6 to 30.6, and from 2.7 to 29.1%/g cell DW (=dry weight), resp.) was apparently a broad distributed character in such yeasts. Depending upon the substrate used, the production of linalool, alpha-terpineol, beta-myrcene, D-limonene, (E)-beta-ocimene, (Z)-beta-ocimene, or carene was observed. Linalool was the main product obtained from geraniol, whereas linalool and alpha-terpineol were the main products obtained through the conversion of nerol. Yet, differently from nerol, the aptitude to exhibit high bioconversion yields of geraniol to linalool was an apparently genus-related character, whereas the ability to produce other monoterpenes was a both genus- and habitat-related character. The possible pathways of bioconversion of geraniol or nerol to their derivatives were proposed/discussed.     

北京市建成区绿地植物物种来源分析

为探讨北京市建成区绿地植物的物种构成、外来植物组成及其在不同功能区的分布,采用机械布点和随机抽样法对北京市建成区绿地植物资源进行系统调查。结果表明：（1）北京市建成区绿地植物外来引进种173种,外来归化入侵种20余种：（2）外来引进种以国内引进为主,境外起源物种中美洲和欧亚区系植物占绝对优势：（3）外来种丰度按大小排列为：大型公园〉高等院校〉居住区绿地〉街头绿地／街心花园〉附属绿地〉街道绿地〉片林绿地,而各绿地类型的入侵种数量没有显著差异。