Phylogeography of five Polytrichum species within Europe

Using allozymes and microsatellites we have analysed the genetic structure among European populations for several Polytrichum species to infer relevant factors, such as historical events or gene flow, that have shaped their genetic structure. As we observed low levels of genetic differentiation among populations, and no decreasing levels of genetic variation with increasing latitude within most of the examined species, no genetic evidence was obtained for a step-wise recolonization of Europe from southern refugia after the latest glacial period for P. commune , P. uliginosum , P. formosum and P. piliferum . The near absence of population substructuring within these species does indicate that extensive spore dispersal is the most important factor determining the genetic structure among European Polytrichum populations. Gene flow levels have apparently been sufficient to prevent genetic differentiation among populations caused by genetic drift, and to wipe out any genetic structure caused by the postglacial recolonization process. On the other hand, increased genetic differentiation of alpine P. formosum populations suggests that mountain ranges might restrict gene flow significantly among Polytrichum populations. In contrast to most examined Polytrichum species, P. juniperinum showed high levels of genetic differentiation and a profound genetic structure. Assuming that gene flow is not more restricted in P. juniperinum , these findings suggest that this species has recolonized Europe after the latest glacial period from two different refugia, one possibly being the British Isles.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society 2003, 78, 203–213.     

应用典范对应分析探讨长白山金发藓科植物的生态位分化

应用典范对应分析(Canonical Co rrespondence Analysis, CCA)对长白山主要生态系统30个样点中的13种金发藓科植物分布与环境因子间的关系进行了研究。发现在长白山地区,金发藓科植物在海拔高度、土壤含砂量、含水量、酸度、光照条件等资源维上存在明显的生态分化现象。13种金发藓科植物中,球蒴金发藓(Polytrichum sphaerothecium(Besch.)C.Mull.、高山异发藓短叶变种(Polytrichastrum alpinum var. brevifolium(R.Br.)Brid.)在海拔上,拟异发藓(Polytrichastrum formosum(Hedw.)G.L.Smith)、变形异发藓(Polytrichastrum dicipensLimpr.)、毛尖金发藓(Polytrichum piliferum Schred.ex Hedw.)、桧叶金发藓(Polytrichum juniperinum Willd.ex Hedw.)在光照上以及大金发藓(Polytrichum commune Hedw.)、直叶金发藓(Polytrichum juniperinum ssp. strictum(Brid.)Nhy.&Sael.)在土壤酸度与水分上的生态要求比较接近。     

Eco-physiological responses of Polytrichum commune to soil contamination by polychlorinated biphenyls

 通过微体繁殖技术在多氯联苯(PCBs)污染土壤基质上进行大金发藓(Polytrichum commune)的室内培养, 研究了不同浓度(5、10和20 mg·kg^–1)低氯PCBs (Aroclor 1242)和高氯PCBs (Aroclor 1254)对大金发藓生理生态指标的影响。经6个月的培养, 大金发藓的密度和盖度分别达93%和50株·cm^–2以上, PCBs处理组与对照组相比无显著差异, 表明PCBs对大金发藓茎叶碎片再生成新植株体的能力没有产生不利影响。大金发藓鲜质量和株高随低氯PCBs (Aroclor 1242)浓度增加而增加、随高氯PCBs (Aroclor 1254)浓度增加而减小, 但均高于对照, 表明PCBs处理对大金发藓的生长具有一定的促进作用。PCBs处理组大金发藓叶绿素a、b以及叶绿素a + b含量较对照组有所增加, 叶绿素a/b值与对照组相比基本没有变化。PCBs处理组大金发藓膜脂过氧化产物丙二醛含量和超氧化物歧化酶活性与对照组相比无显著差异, 谷胱甘肽含量较对照组显著增加, 表明谷胱甘肽在大金发藓体内活性氧清除过程中起重要作用。总体来看, 大金发藓能在所设浓度的PCBs范围内正常生长, 对PCBs有较强的耐性。     

Carbohydrate and lipid levels in two Polytrichum moss species growing on the Alaskan tundra

Two tundra Polytrichum moss species were sampled in the field near Barrow, Alaska, three times during the growing season. Lipid, sugar, and starch concentrations of the green above ground shoots and below ground rhizomes were analyzed. Lipid and TNC (sugar + starch) concentrations were higher in Polytrichum commune growing on raised polygon rims than in Polytrichum alpinum. There were no significant differences between the two populations of P. alpinum. Green parts had significantly higher lipid concentrations than rhizomes in P. commune but not in P. alpinum. Both species had significantly higher sugar concentration in green shoots and higher starch concentrations in the rhizome and sugar concentration varied significantly in both species. Seasonal variation of TNC concentration levels were significant only in P. commune. A statistically significant positive relationship was found between lipid and TNC concentration while a stronger statistically significant negative relationship was found between sugar and starch concentration. The first is interpreted as an adaptation to drought in surface waxes and osmoticum while the second is interpreted as conversion indicator depending on tissue and use. Polytrichum mosses resemble evergreen vascular plants in their seasonal stability of these compound groups.     

Response of Norwegian alpine communities to nitrogen

The effect of nitrogen pollution on species cover was tested in the Dovre mountains, south-central Norway, through a three-year fertilisation experiment in a low-alpine community and a two-year one in a middle-alpine community, both dominated by lichens. The doses used were 0.7, 3.5 and 7 g N/m², the highest doses corresponding to 1.75 and 3.5 times the annual deposition of nitrogen in southwestern Norway. The results were tested using the SAS/STAT/MIXED procedure. Using the Bonferroni correction, the procedure did not confirm a change in the cover of single species due to increased nitrogen supply, but there seemed to be a general tendency for an increase in cover in the low-alpine Cetrarietum nivalis community. When less rigorous tests were applied, Arctostaphylos uva-ursi, Vaccinium vitis-idaea, Polytrichum piliferum, Cetraria nivalis and Cladonia mitis in Cetrarietum nivalis, and Cladonia coccifera in Phyllodoco-Juncetum trifidi seemed to indicate that nitrogen had some effect on these communities. The lack of a clear response in single species may be due to the application of low doses over a short time-span in an environment characterised by large interannual variations in climate, the deficiency of other important nutrients, dryness, the low growth potential of the species involved, and, to some extent, the community structure.     

Molecular Markers Reveal Cryptic Species Within Polytrichum commune (Common Hair-Cap Moss)

Abstract: Based on morphological characters only, the taxonomy of the moss genus Polytrichum has still not been fully resolved. Application of molecular techniques might clarify some of these problems. Within P. commune s.l., the taxonomic status of several varieties, e.g., P. commune var. commune and P. commune var. uliginosum, is still debated. This study uses allozyme electrophoresis to show that there are two distinct allozyme multi-locus genotypes within our P. commune samples. These two multi-locus genotypes coincide with both differences in morphology and differences in habitat association. This division is corroborated by observations from different Danish and Dutch populations. Based on these results, in connection with a genetic comparison of the two infraspecific taxa of P. commune s.l. with a related species P. formosum, we argue that P. commune var. commune and P. commune var. uliginosum are two genetically distinct entities with fixed morphological differences and a considerable niche differentiation. They should, therefore, be regarded as two distinct species: P. commune and P. uliginosum.     

海南岛霸王岭热带低地雨林植被恢复动态

热带次生林具有重要的物种保育和固碳功能, 然而高强度的干扰会导致次生林早期出现类似季雨林的阶段, 因而群落恢复速度和方向是当前热带生态学研究中最为关注的议题之一。该文以海南岛在刀耕火种弃耕地形成的不同演替阶段的次生林为研究对象, 比较森林不同恢复时间(12年、25年、55年)群落中的不同年龄(幼树、小树、成年树)个体与低地雨林老龄林的物种组成、多样性和群落结构差异, 探讨刀耕火种弃耕地恢复过程中的群落组配过程。首先, 在海南岛霸王岭林区内建立7个1 hm²(100 m × 100 m)的样地, 并调查样地内所有胸径≥ 1 cm的木本植物个体(不包括木质藤本)的种类、胸径大小和树高。无度量多维标定法(NMS)排序结果表明, 刀耕火种弃耕地恢复群落与老龄林的物种组成存在明显差异, 并且其物种组成差异随着径级增加而逐渐减小。刀耕火种弃耕地群落物种累积速度缓慢, 25年和55年恢复群落的种面积、种个体和种多度曲线无差异, 存在一个明显的停滞阶段。与物种组成相比, 群落结构恢复相对较迅速, 但仍没有形成老龄林阶段中的复杂结构。萌生个体在早期恢复群落中占有较高比例, 其个体密度和胸高断面积分别占总数的39.9%和55.9%, 但在恢复中后期迅速降低。刀耕火种弃耕地恢复群落中以先锋种和非先锋喜光种为主。虽然耐阴种随演替而逐渐增加, 但恢复中后期群落中的耐阴种重要值仅为老龄林的27.7%。这些结果表明, 虽然刀耕火种弃耕地恢复群落缓慢地逐渐接近最终恢复目标, 但仍然存在 很大的不确定性。刀耕火种弃耕地恢复过程中的异速恢复和停滞阶段需要纳入今后群落演替模型构建和森林固碳效益核甘共苦算中。     

青藏高原东缘海螺沟冰川退缩区植被原生演替的氮磷动态

在青藏高原东缘海螺沟冰川退缩区植被原生演替序列的典型地段依次设置7个采样点(冰川退缩0、10、30、40、50、80和127年),测定各演替阶段表层土壤与植被各层氮(N)、磷(P)含量及生态系统生物量,分析不同演替阶段N、P养分的积累与循环特征。结果表明:乔木层叶、枝、根的N、P含量随演替下降,而干的N、P含量在演替末期较高,凋落物与土壤O层N、P含量的变化趋势与乔木层叶和枝一致。生态系统的N、P贮量均随演替逐渐增加,演替初期生态系统N的积累主要依靠植被层,演替末期尤其是植被层形成顶极群落以后,土壤成为生态系统中最主要的N库;植被层的P贮量在冰川退缩后的80年样地超过了表层土壤。生态系统N、P养分的积累速率在演替中期较快,且表现为表层土壤＞乔木层＞林下植被层;演替中期阔叶林阶段N、P养分的循环系数高于演替末期的针叶林阶段,而利用效率则低于针叶林阶段。可见,针叶树种养分循环低但利用率高的机制有利于同其他物种竞争,从而最终形成顶极群落。     

高寒牧区中华羊茅人工草地退化演替的数量特征研究

对中华羊茅人工草地退化演替数量特征的研究表明,植物群落组分种的数量、丰富度指数、多样性指数和均匀度指数均随演替的进程而增加,生态优势度指数呈下降趋势。对25个组分种的重要值、生态位宽度及生态位重叠值计测的结果表明,一些阔叶杂草（如细叶亚菊、西伯利亚蓼等）是退化演替过程中入侵人工草地的先锋植物,比其他杂类草具有较大的生态位宽度值,其重要值在演替过程中呈逐年上升趋势。以中华羊茅为其中一个组分种的植物种对间的生态位重叠值,在大多数情况下小于两种阔叶杂草种对间的生态位重叠值。阔叶杂草入侵是导致人工草地退化的一个重要影响因素。     

Direct identification of the common cheese contaminant Penicillium commune in factory air samples as an aid to factory hygiene

F. LUND. 1996. Creatine sucrose dichloran agar (CREAD) was used as a selective medium for Penicillium commune and related species found in air samples in a cheese factory. Using growth and simple colony characters on CREAD together with detection of indole metabolites with a filter paper method, it was possible to identify all 22 P. commune isolates from a total of 43 Penicillium isolates. Penicillium commune numbers on CREAD were compared with those found on a general isolation medium, dichloran 18% glycerol agar.     

The Community Dynamics of the Forest Secondary Succession in Heishiding Natural Reserve of Guangdong Province

Studying on the community structure, species composition and species diversities of the secondary succession of lower subtropical forest in Heishiding Natural Reserve, Guangdong Province, the following results were obtained. In 2 ~4 years of restored stage the seedlings of pioneer species, heliophytes and mesophytes occur simultaneously. In 10 years of restored stage pioneer species are superior as heliophytes maintain stable and mesophytes are being decreased. In the stage of mixed forest pioneer species are on the decreasing and heliopytes are on the increasing trend. In the stage of evergreen broad-leaved forest dominated by heliophytes pioneer species are being declined, heliophytes are dominant and mesophytes are being increased. In the stage of evergTeen broad-leaved forest dominated by mesophytes heliophytes are being declined and mesophytes are superior. The vertical structure, horizontal structure, the structure of species composition determine stability of communities in secondary succession process. The vertical structure of community is building up in the stage of restoration. The community is composed of the stands under the third class. The forest canopy is not stratified. The individual density is stable. From restored stage to mixed forest the vertical structure of community is diversified. There are the third and forth class stands in community. The tree layer is divided into three sub-layers. The individual density declines rapidly because of self-thinning. In the mixed forest the vertical stmcture is relatively stable. The abundance of the fifth class stands and area of breast height reach the first peak in the succession serial. The individual density increases rapidly. In stage of evergreen broad-leaved forest dominated by heliophytes, the vertical structure changes largely. The abundance of the fifth class and area of breast height decline rapidly, but the individual density changes slowly. In the stage of evergreen broad-leaved forest dominated by mesophytes, the vertical structure of community is stable and the composition of every stand class becomes more stable. The area of breast height is the biggest in the succession serial. When succession develops, the coverage of communities increases gradually but the turnover rate of species declines. The species composition tends to be stabilized. The diversity of species and community evenness increase gradually thus, the ecological dominance declines gradually.     

Plant strategies and secondary succession on Brittany heathlands after severe fire

Abstract. Plant succession on heathlands subjected to major fire disturbance and humus burn in 1976 was studied over twelve years following burning. Life history strategies of principal heathland species are described with reference to concepts outlined by Grime (1979) and Whittaker & Goodman (1979). Heathlands and closely related communities are characterised by dominance of speciestolerant of physical stress (‘S’ strategists) whereas species which colonise disturbed sites are closer to rude-rals (‘R’ strategists). After severe burning three main successional patterns were identified. They depend on water and nutrient availability relative to temporal population dynamics. Recovery of heathland is often retarded due to monospecific dominance, e.g. of Polytrichum commune, Molinia caerulea and Betula pubescens. These patterns of secondary succession illustrate the inhibition model advanced by Connell & Slatyer (1977).     

群落演替对呼伦贝尔草地两种优势植物繁殖分配及生态化学计量的影响

为了探究草地群落演替过程中不同优势种的生理生态适应性,本研究采用空间代替时间序列的方法,分析呼伦贝尔草地米氏冰草群落—米氏冰草+冰草群落—冰草群落演替系列的土壤养分、两优势种的生物量及C、N和P含量。结果表明: 随着米氏冰草群落—米氏冰草+冰草群落—冰草群落的演替,土壤全碳、全氮、速效氮及速效磷含量均显著升高;米氏冰草和冰草叶、茎和根的N、P含量及N/P均显著升高,而各构件的C/N降低;米氏冰草叶的C含量及冰草叶、茎和根的C含量均显著升高。米氏冰草叶C/P及冰草根和叶C/P均显著升高,而米氏冰草根和茎C/P及冰草茎C/P均显著下降。在米氏冰草+冰草共优势种群落中,米氏冰草通过降低茎和根C含量,增加叶C的积累,提高其种间竞争力, 而冰草通过降低根冠比和生殖比来适应环境变化。米氏冰草在不同群落中均受N限制(N/P<14);而冰草在单优势种群落中受P限制(N/P>16),在共优势种群落中受N和P限制(14相似文献   

Inorganic chemical investigations in the forest biosphere reserve near Kalinin,USSR

Lanthanides (rare-earth elements) were quantitatively determined by atomic emission spectrometry/inductively coupled plasma (AES/ICP) in various plants (Picea abies, Vaccinium vitis-idaea, Vaccinium myrtillus, Polytrichum commune, Sphagnum spec., and Hypogymna physodes) collected in the Forest Biosphere Reserve 350 km northwest of Moscow (USSR). Compared with previously established background values for lanthanide elements in central Europe, the rare elements determined in the USSR samples appear in lower concentrations. The lichen Hypogymna physodes can be characterized as an extreme accumulator of lanthanide elements up to a factor of ten compared to the other plant species collected in the Forest Biosphere Reserve. With regard to the lanthanide contents in plants collected in a German reference forest ecosystem, it can be seen, that the German samples represent without exception higher lanthanide values. Leaves of Vaccinium vitis-idaea display contents 3–4 times higher, leaves of Vaccinium myrtillus show concentrations higher by a factor of about 0.3, approximately twice the contents were determined in the German samples of Polytrichum formosum and P. commune, and the values in the German samples of the Sphagnum species are about 3 times that of the Soviet samples. As pointed out for pollution by heavy metals in part I of this series, the Forest Biosphere Reserve is generally characterized by lower contents of lanthanides in the vegetation cover than a comparable forest ecosystem (Grasmoor near Osnabrück, F.R.G.) in central Europe.     

Inorganic chemical investigations in the Forest Biosphere Reserve near Kalinin,USSR

About 50 naturally occurring chemical elements were quantitatively determined by AAS, ICP/AES, ICP/MS and INAA in the main vegetation cover of the Forest Biosphere Reserve near Kalinin, USSR. The lichen Hypogymna physodes, which was studied and compared with other plant species, accumulates the elements Al, As, Br, Ce, Co, Dy, Eu, Fe, La, Lu, Pb, Pr, Sb, Sc, Sm, Th, Tm, V, Zn, and Zr. At the same time, a depletion of the alkaline elements Na, K, Rb, and Cs and the alkaline earth elements Mg and Ca is to be observed. Within the moss cover certain heavy metals are also accumulated by Polytrichum commune and the various Sphagnum species. As in Hypogymna physodes there is also a pronounced depletion of the alkaline earth metals Mg and Ca, but contrary to Hypogymna physodes there is a simultaneous accumulation of the alkaline metals K and Rb in Polytrichum commune and additionally of Na in the Sphagnum species. This is in agreement with studies showing different behaviour for the element potassium in Polytrichum formosum in the course of several vegetation periods. Potassium accumulation was found at the beginning of the vegetation period contrary to the dilution effect due to biomass supply. The depletion of Mg and Ca in all accumulator plants seems to be a direct consequence of heavy metal concentration since this phenomenon occurs irrespective of the site, as was shown by a comparison with data from a German forest ecosystem (Grasmoor near Osnabrück). Clear bioindication behaviour of Polytrichum commune, the various Sphagnum mosses and Hypogymna physodes was found for the elements Mn, Ni, Sn, Th, Cr, Mo, and S since the same accumulation and depletion behaviour was observed for all three plants as a function of site. These plant species could thus be used as bioindication cadasters in the sense of ARNDT. The higher shrub plants examined (Vaccinium vitis-idaea and Vaccinium myrtillus) show the already known accumulation of the elements Ba and Mn (up to 4000 mg/kg of Mn for Vaccinium myrtillus). In general the concentration ranges for many elements are more restricted in higher plants.     

Diversity and community composition of herbaceous plants in different habitat types in south‐east Cameroon

The composition of herbaceous vegetation was evaluated with the aim of characterizing forests at various ages of stand development. Herb stems were sampled in 250 4‐m² square plots distributed within six habitat types. A total of 36 herb species belonging to 15 families were recorded. Species richness did not significantly differ between habitat types. Most herb species occurred in all habitat types and were therefore generalists. However, a few indicator herb species were detected, and the results roughly suggested that herb species of the families Poaceae and Araceae were indicative of late successional forests; Zingiberaceae are indicative of early successional forests; and Commelinaceae, Costaceae, Cyperaceae and Marantaceae are indicators of flooded habitats. Species diversity and stem density of herbaceous plants did not change with forest succession as a decrease in abundance and frequency of occurrence of pioneer species in late successional forests was counterbalanced by the presence of generalist and late successional species. However, increasing proportions of dwarf stems in late successional forests translated to changes in the vertical structure of herbaceous plant communities. Herbivory pressure by gorillas did not have a notable effect on herbaceous plant community development. This study contributes to the definition of herbaceous ecological indicators of forest succession in different settings.     

平茬对岩黄芪属植物生物学性状的影响

探讨了3种岩黄芪属植物平茬与未平茬植株的生物学性状.结果表明,平茬后3种岩黄芪属植物植株的多种性状与未平茬植株无显著差异,但平茬植株基部新生枝条数比未平茬植株增加1.91倍.平茬不仅复壮了植株个体,提高了产量,而且提高了家畜可食部分（叶+嫩茎）的比例.平茬岩黄芪属植株5～8月生物量中以叶和嫩茎为主,在9月,由于枝条木质化,家畜不可食部分迅速增加,平均不可食部分占总生物量的69.26％.而未平茬的岩黄芪属植株由于有上一年残留的枯死枝条,因而5～8月一直有老茎存在,9月份家畜不可食部分平均达到77.79％.岩黄芪属植物可在植物生长的第2年进行平茬,应在8月底以前进行收割.8月平茬处理3种岩黄芪灌丛的叶面积指数高于对照,散射光系数低于对照,说明在8月平茬处理植株的生长高于对照植株,生长更为繁茂.     

Hybridization and asymmetric reproductive isolation between the closely related bryophyte taxa Polytrichum commune and P. uliginosum

Based on genetic differentiation, the haploid dioecious bryophyte taxa Polytrichum commune and P. uliginosum have been inferred to be completely reproductively isolated. However, analysing diploid sporophytes from a sympatric population for three diagnostic microsatellite markers, we show here that reproductive isolation between these taxa is far more complex and highly asymmetric. Isolation between female-P. communex male-P. uliginosum seems to be complete and prezygotic (or early postzygotic) as no hybrid sporophytes were observed on P. commune females. In the other direction ( female-P. uliginosumx male-P. commune) isolation was clearly postzygotic as high frequencies of hybrid sporophytes were found on P. uliginosum females. However, during maturation these sporophytes showed irregular development, indicating that hybrid sporophytes are unlikely to produce ripe spores. Mechanisms possibly underlying this asymmetric reproductive isolation pattern are discussed. Notwithstanding hybrid offspring being unlikely, the high frequency of hybrid sporophytes observed suggests that viable spores may be formed occasionally through such rare processes as chromosome nondisjunction, possibly giving rise to allodiploids. Allodiploids have been reported in Polytrichum (and other bryophyte genera). Studies such as the one presented here will therefore help to elucidate the evolutionary importance of interspecific hybridization and allodiploidization in bryophyte speciation.     

大亚湾大鹏澳水域春季浮游植物优势种的演替

根据2002年4月28日～5月27日大亚湾大鹏澳内每日采样的现场连续观测资料,使用主分量分析方法和多元回归方法,分析浮游植物优势种类之间的关系及影响其生长与演替的主要理化因子,建立春季浮游植物优势种类的演替模型。模型表明,中肋骨条藻和柔弱菱形藻之间为竞争关系;与浮游植物(以硅藻为主)生长密切相关的理化因子为温度(T)、溶解氧饱和度(DOsat)、铵氮(NH4-N)、亚硝酸氮(NO2-N)、磷酸盐(PO4-P)、硅酸盐(SiO3-Si)。影响中肋骨条藻的理化因子还有盐度(S)和氮磷比值(NO3／PO4)。并根据优势种类发生演替期间的环境变化(降雨),分析了浮游植物优势种由中肋骨条藻演替为柔弱菱形藻的过程。     

晋西吕梁山严村流域撂荒地植物群落替中的物种多样性变化

用ＤＣＡ排序研究了黄土丘陵区撂荒地上植物群落演替的趋势和方向,用６种多样性指数分析了物种丰富度、均匀度和综合多样性在演替过程中的变化。随着演替的进展,物种丰富性显著增高,均匀性逐渐降低,综合多样性逐渐升高。