近50年山东省农业气候资源变化特征

利用山东省90个气象站1961-2010年逐日气象观测数据,比较分析了该区域冬小麦和夏玉米生长季光、热、水等农业气候资源的时空变化特征.结果表明: 研究期间,山东省冬小麦和夏玉米生长季各项气温指标均呈显著升高趋势,冬小麦生长季升高趋势更明显;日照时数显著减少;降水量和干燥度无显著变化;夏玉米生长季蒸散量显著减少.冬小麦和夏玉米生长季各农业气候资源呈大致的经向或纬向递增或递减的空间分布.不同区域各农业气候资源历年变化特征差异明显,鲁西地区各气温指标升高趋势较弱,鲁中和鲁西南地区日照时数减少趋势最显著,鲁西地区蒸散量和干燥度减少趋势最显著,鲁中和鲁东南地区冬小麦生长季降水量增加趋势较明显,鲁中和鲁南地区夏玉米生长季降水量增加趋势较明显.山东省热量资源的增加有利于冬小麦生长季各阶段的发育,但植物病虫害的防治难度及农作物遭受高温热害的风险加大,日照时数减少不利于农作物生长期的光合作用,蒸散量减少则有利于土壤水分的保存.
     

Fine‐scale vascular plant species richness in different alpine vegetation types: relationships with biomass and cover

Abstract. Vascular plant species richness was related to biomass and vegetation cover in nine different alpine vegetation types on the Hardangervidda mountain plateau, western Norway. Each vegetation type was sampled within an 8m × 6m area, and the species‐richness pattern analysed. Evidence for a unimodal relationship between species richness and both biomass and cover was found at the within‐vegetation type scale. Cover was a better predictor for species richness than biomass, suggesting that light may be an important factor influencing species richness at this scale in alpine vegetation. The possibility that the results are an artefact of small grain size is also discussed, and several arguments for an ecological explanation of the humpback relationship between species richness and cover are discussed.     

湖北兰科植物多样性及其区系地理特征

湖北植被尤其是鄂西地区,在近代以来备受植物学家的关注。该研究基于植物标本、文献资料与野外调查成果,整理出湖北兰科植物名录,结合湖北的地形与气候特征分析了湖北兰科植物的分布格局、区系及多样性特征。结果表明:湖北兰科植物主要分布在西南、西北、东北及东南部山区,以鄂西山地最为丰富,中南部江汉平原最少,900~1 200 m中海拔地段丰富度最高;物种多样性由南至北、由西至东呈递减趋势,鄂西南与鄂西北之间具有最大相似性;除拟兰亚科(subfam.Apostasioideae)外的5个亚科湖北均有分布,计有15族54属141种,单种属和寡种属分别占总属数的50.00%和33.33%;湖北兰科植物东亚分布成分占40.43%,中国特有种占总种数的41.84%,东亚区系主体突出,中国特有成分所占比例较大,其中中国—日本成分占优势;温带属性较强,亚热带向温带过渡特征明显,有25个热带分布属及27个温带分布属,热温比为0.93,种级水平的热带分布类型占8.51%,温带分布类型占91.49%;一些稀缺种在台湾与湖北的间断分布,表明两者植物区系有较强的关联性;湖北兰科植物区系与西南及横断山区联系密切,是与东部地区植物区系交流的中转站。     

长白山高山苔原雪斑大白花地榆群落土壤氮素动态与生产力的关系

在高山苔原冬季积雪覆盖的群落生长季短, 但明显比周围群落生长茂盛。为了说明雪斑地段群落生长机理, 对长白山苔原雪斑土壤氮素动态以及大白花地榆(Sanguisorba sitchensis)群落生产力进行了连续测定。雪斑群落土壤冬季相对温暖, 最低日平均温度-1.4 ℃, 裸露地段-16.9 ℃, 全年水分条件充足; 积雪期凋落物分解和氮矿化均在进行, 土壤具有很高的氮素含量及矿化速率。大白花地榆地上部分净初级生产力为4 046 kg·hm^-2·a^-1。正是独特的水热条件和养分条件, 以及具有很大的叶面积同化器官, 高山苔原雪斑地段的大白花地榆群落才得以维持生存并表现出很高的生产力水平。     

Phytogeography of Genu and Homag,two mountains with an Irano–Turanian flora in the Saharo–Sindian regional zone,south Iran

The Saharo–Sindian regional zone encompasses the flat and arid areas of North Africa, the Arabian Peninsula, southern Iran and the deserts of Pakistan and west India. There are some scattered mountains situated within this area, like Hoggar in Sahara, Saint Catherine in Sinai and Genu and Homag in southern Iran. These highlands serve as interglacial refugia for cold adapted plant species. In the present study, phytogeographical patterns and relationships of the flora of Genu and Homag mountains are described and discussed in relation to the phytogeography of the flora of low‐lying Hormoz Island. According to a chorological assesment of the flora, Genu and Homag mountains belong to the Irano–Turanian region with 59% of the species restricted to this area. In contrast, the surrounding lowland plains are part of the Saharo–Sindian area with a rather high proportion of widespread species (17%) and Somalia–Masai‐linking elements (20%). It is noteworthy that several Turanian enclaves also occur in the lowland zone. Furthermore, the distributional patterns imply that the mountainous Irano–Turkestanian region is an integrated area which is supposedly distinct from the Turanian lowland areas in the north and from the Saharo–Sindian lowland areas in the south. On the other hand, the expansive floras of Turanian and Saharo–Sindian regions are linked to each other. Endemic species in lowland areas in south Iran are mostly either frost sensitive vicariants of cold adapted Turanian species or of Saharo–Sindian origin, while the highland endemics in the area trace their origins to the Irano–Turkestanian region.     

Wild reindeer foraging-niche organization

Part 1: Diet selection was studied on free-ranging reindeer fitted with an esophageal fistula (EF) and by analysis of rumen samples from reindeer shot in the field. Plant density was assessed from quadrats on field plots. Three measures of palatability were used, the nitrogen, fiber, and total non structural carbohydrate (TNC) contents of samples from clipped vegetation. As lichen density decreased the EK reindeer included progressively more vascular litter and pieces of winter dormant species in their diet. Diets with highest TNC and N/F and the lowest fiber, providing the most readily digestible diets, were selected. The combined density-quality criterion gave the best prediction of their diets. In summer, forbs, and to some extent grasses and dwarf shrubs, were selected. Plants of highest density and in an early growth phase gave the best prediction of summer diets. In winter the variety of vascular plants utilized increased with increasing herd size and decreasing density of lichens in the vegetation. The width of diets was a function of diversity of available plants. It is suggested that dietary selection by reindeer has been a three stage process: evolution of a gastro-intestinal system capable of digesting lichens containing secondary compounds, behavioural tracking of the plant production pulse, and diet width scaling according to density-quality of all potential foods. Part 2: Wild reindeer closely followed the wave of vascular plant production in spring and summer with a significant correlation being found between the daily foraging time per habitat type and the highest concentration of green phytomass. Snow-bed meadows were the most consistently selected vegetation type by the four herds studied, viz. Hardangervidda, Snøhetta, Prudhoe Bay, and Svalbard, during the summer. Habitat niche-breadths were narrow during the winter, largely due to the limitation of access to the food supply by the snow-cover, broadened as the landscape became clear of snow, narrowed again with the initiation of plant growth and broadened once more as the wave of plant production reached all habitat types. At high levels of food resources the alpine herd (Hardangervidda) narrowed the feeding niche breadth (or adopted a selective feeding strategy) as the habitat niche breadth increased. The high arctic herd (Svalbard) living in the least productive environment, at the same time of year adopted a generalist feeding strategy as their habitat niche breadth expanded. Part 3: In this part the temporal organization of a low-alpine herd of reindeer (Hardangervidda) is described, and subsequently compared with those of two arctic herds. Their foraging efficiencies under different degrees of food availability were analysed, in order to test the hypothesis that food intake changes in response to the prevailing state of the food resources. The number of daily feeding bouts increased from 2 to 6 as the diet changed from the winter to the summer pasturage. Strong winds in winter and insect harassment in summer severely depressed the daily time spent foraging. When these environmental factors were accounted for no significant inter-seasonal differences in daily foraging time of the low alpine herd were found; on average 50% of each day was spent grazing, of which 78% of the time was spent on actual ingestion (feeding rate). The feeding rate within the active periods varied with the snow-depth, due to the need to dig a food crater in the snow and due to the particular selective feeding strategy adopted. The data from the present and from other studies suggest that the foraging efficiency of wild reindeer, expressed as their daily food intake follows a Holling type II functional response as food availability changes. Part 4: Sheep is the only sympatric ruminant which grazes with the reindeer on alpine pastures in Norway. The inter-specific niche relationships ot the wild reindeer and the domestic sheep in summer were studied on part of the western Hardangervidda. to test the hypothesis of inter-specific competition. Three niche dimensions were meas-ured, diel, habitat utilization, and spatial distribution. The estimates of the degree of overlap obtained suggest that this is relatively high for diet and habitat utilization but low for spatial distribution, which leads to a low degree of foraging interference. Since the intensity of both interspeeific and intra-specific competition depends on the ratio of the herbivore densities to the food resource density, the degree ol overlap in utilization by the two species tell us nothing about the degree of competition. Present numbers of both species on Hardangervidda have a beneficial influence on the vegetation, by opening-up the shrub-layer canopy and thus facilitating the main-tenance of grasses and forbs in the field layer, which has a higher carrying capacity for ruminants. The balance between the beneficial effects and inter-generic competition (if any) deriving from the present-day stocking rales is so tar unknown. Only long-term monitoring of the performance of both populations will shed light on this competitive aspect.     

Biodiversity and phytogeography of the alpine flora of Iran

Iran is a mountainous country. Zagros and Alborz mountains reach altitudes of more than 4,000 m. Alpine regions are above timber-line, which is not easy to recognize, since aridity is prominent in most regions. The alpine zone in Alborz lies between 3,000 and 4,000 m, the nival zone is above 4,000 m, locally varying by some hundred meters. A first evaluation of vascular flora shows that 682 species belonging to 193 genera and 39 families are known from the alpine zone of Iran. The alpine zone is commonly characterized by many species of hemicryptophytes and thorny cushions. Species numbers decline very strongly with increasing altitude. In this paper biogeographical patterns of the alpine flora of Iran have been discussed and distribution maps of 44 species are illustrated. New data indicate a transitional situation of the Iranian mountains between Anatolia/Caucasus and the Hindu Kush, but with a strong own element with high endemism and remarkable relict species. Ca. 58% of the alpine flora of Iran are endemic and subendemic. The Zagros Mountains harbor high endemism which justify considering this area as a separate floristic province. Based on the evaluation of published data from 682 known alpine species ca. 160 species have been known only by one record, 110 species by 2–3 records and 87 endemic species have been known only based on the type location. These plants need a strong conservation and protection management since the fragile ecosystems are often very restricted, small and very isolated, nonetheless grazing and overgrazing are still common threats.     

幕阜山脉石松类和蕨类植物多样性及生物地理学特征

通过资料收集及野外调查, 得出幕阜山脉地区共有石松类和蕨类植物26科72属261种, 具有一定的东西过渡性, 为鳞毛蕨-铁角蕨植物区系, 最大属为鳞毛蕨属(Dryopteris) (29种)。其中, 庐山的物种丰富度较高(224种), 以铁角蕨属(Asplenium)为主; 幕阜山的物种密度较大(2.09种/km ²), 以卷柏属(Selaginella)为主; 九宫山以瓦韦属(Lepisorus)为主; 三者共通种有95种, 新特有现象较丰富。该区属种分化限制明显, 表现在单种科、属及寡种科、属占总科数的60%及总属数的80%。从区系成分看, 该区科、属以热带成分为主, 科和属的热带性成分与温带性成分比值(R/T值)分别为2.6和2.3。与同纬度带山地石松类和蕨类植物属的R/T值比较, 中亚热带与北亚热带交界带的蕨类植物属的R/T值在2.18-2.36之间; 种的R/T值为0.2, 为热带成分的5倍, 表现出明显的温带性质, 是罗霄山脉植物区系温带成分的重要组成部分。该区石松类和蕨类植物区系与华东、华南植物区系联系比较紧密, 表现出华东与华南两区系成分的交汇。     

Phylogeography of the high alpine plant Senecio halleri (Asteraceae) in the European Alps: in situ glacial survival with postglacial stepwise dispersal into peripheral areas

Whether alpine plant species survived Pleistocene glaciations in situ on high alpine nunatak mountains is still under debate. To test this hypothesis, Senecio halleri, a high alpine and endemic species with a narrow distribution range in the European Alps, was chosen as a model organism. Polymerase chain reaction-restriction fragment length polymorphisms of chloroplast DNA (cpDNA PCR-RFLPs) were used in a phylogeographic analysis of 14 populations of S. halleri, covering its total distribution area. The results of haplotype diversity and distribution gave evidence of in situ glacial survival on siliceous central-alpine nunatak mountains in two areas, southwest and northeast of the Aosta valley. According to the absence of genetic differentiation between these two nunatak areas (based on amova), nested clade analysis implied a history of preglacial gene flow, in situ survival and extinction of intermediate populations during glaciation and postglacial stepwise recolonization of peripheral and intermediate areas.     

Effects of the abandonment of alpine summer farms on spider assemblages (Araneae)

In parallel with the current effects and responses to climate change ongoing changes of land use strongly affect alpine areas. The aim of this study was to analyse spider assemblages occurring on farmlands with differing stages of land use intensity. We collected the ground-dwelling spider fauna of semi-natural grasslands in currently farmed and abandoned farmland in the alpine zone of Hardangervidda, Norway, using pitfall traps. Trapping during the whole vegetation period resulted in 1,548 individuals belonging to 39 species of spiders. Linyphiids and lycosids dominated. The total number of species differ little between sites, but there was a general trend of increasing proportions of lycosids, gnaphosids and thomisids individuals and species, and a decrease in the proportion of linyphiids with farmland abandonment. Two main groupings of spider assemblages were found using a principal component analysis: One grouping was characteristic of intensely disturbed sites, mainly dominated by typical pioneer species. The other was characteristic of abandoned and less disturbed sites, dominated by widespread species. The abandonment of summer farms led to a succession in spider assemblages, including a decline in spider species with a high ballooning activity and an increase of species with a larger body size. We suggest that the main reason lies in the absence of disturbance by grazing including differing vegetation architecture and the proportion of bare ground with abandonment. Spider assemblages react quickly to environmental changes that occur in alpine habitats after abandonment. Thus, it is necessary to include spiders and other invertebrate animal indicator groups in field studies and experiments dealing with grazing impacts on alpine habitats.     

OBSERVATIONS ON THE LICHEN FLORA OF HIGH GROUND IN THE WEST OF IRELAND

The lichen flora of high ground in the west of Ireland is described by reference to four localities (Brandon Mountain, Muckanaght, Ben Bulben, Slieve League). These were selected on the basis of their reputation for calcicolous alpine vascular plants and for being some of the most highly oceanic mountains in Europe. The montane element in the lichen flora is strictly limited, populations being small and isolated, although sub-montane species are more frequent. A small group of 44 species has been identified, which is 30% fewer than is found in either the Lake District or Snowdonia; their distribution and ecology are described. The margin of high-level tarns on Brandon Mountain support communities of outstanding importance, includingRinodina fimbriata, new to the British Isles. Seventeen lichens are reported as being new to Ireland. 1996 The British Lichen Society     

Seasonal dynamics of mobile carbon supply in Quercus aquifolioides at the upper elevational limit

Many studies have tried to explain the physiological mechanisms of the alpine treeline phenomenon, but the debate on the alpine treeline formation remains controversial due to opposite results from different studies. The present study explored the carbon-physiology of an alpine shrub species (Quercus aquifolioides) grown at its upper elevational limit compared to lower elevations, to test whether the elevational limit of alpine shrubs (<3 m in height) are determined by carbon limitation or growth limitation. We studied the seasonal variations in non-structural carbohydrate (NSC) and its pool size in Q. aquifolioides grown at 3000 m, 3500 m, and at its elevational limit of 3950 m above sea level (a.s.l.) on Zheduo Mt., SW China. The tissue NSC concentrations along the elevational gradient varied significantly with season, reflecting the season-dependent carbon balance. The NSC levels in tissues were lowest at the beginning of the growing season, indicating that plants used the winter reserve storage for re-growth in the early spring. During the growing season, plants grown at the elevational limit did not show lower NSC concentrations compared to plants at lower elevations, but during the winter season, storage tissues, especially roots, had significantly lower NSC concentrations in plants at the elevational limit compared to lower elevations. The present results suggest the significance of winter reserve in storage tissues, which may determine the winter survival and early-spring re-growth of Q. aquifolioides shrubs at high elevation, leading to the formation of the uppermost distribution limit. This result is consistent with a recent hypothesis for the alpine treeline formation.     

Intraseasonal variation in pollination intensity and seed set in an alpine population of Ranunculus acris in southwestern Norway

I studied aspects of the pollination and reproduction ecology of an alpine population of the circurnpolar Ranunculus acris (Ranunculaceae) at Hardangervidda, southwest Norway Dipteran families, mainly Muscidae and Anthomyudae, were the most frequent flower visitors and pollinators A single visit by these insects resulted in a seed set of c 18% of the total potential Visitation rates were highest early m the flowering season The longevity of individual flowers of early flowering plants was c 3 d shorter than that of mid-season flowering individuals Insect pollinators moved short distances between flowers and they mostly visited near neighbour plants Expenments showed that Ranunculus acris was self-incompatible and thus dependent on insect visitation for seed production Early flowering individuals had a very high seed set relative to individuals flowering in mid- and late season, suggesting a strong selection pressure for early flowering in the population Seed production in this Ranunculus acris population seems to be limited by severe climatic conditions and a low pollination intensity     

Heterogeneity, speciation/extinction history and climate: explaining regional plant diversity patterns in the Cape Floristic Region

This paper investigates the role of heterogeneity and speciation/extinction history in explaining variation in regional scale (c. 0.1–3000 km²) plant diversity in the Cape Floristic Region of south‐western Africa, a species‐ and endemic‐rich biogeographical region. We used species‐area analysis and analysis of covariance to investigate geographical (east vs. west) and topographic (lowland vs. montane) patterns of diversity. We used community diversity as a surrogate for biological heterogeneity, and the diversity of naturally rare species in quarter degree squares as an indicator of differences in speciation/extinction histories across the study region. We then used standard statistical methods to analyse geographical and topographic patterns of these two measures. There was a clear geographical diversity pattern (richer in the west), while a topographic pattern (richer in mountains) was evident only in the west. The geographical boundary coincided with a transition from the reliable winter‐rainfall zone (west) to the less reliable non‐seasonal rainfall zone (east). Community diversity, or biological heterogeneity, showed no significant variation in relation to geography and topography. Diversity patterns of rare species mirrored the diversity pattern for all species. We hypothesize that regional diversity patterns are the product of different speciation and extinction histories, leading to different steady‐state diversities. Greater Pleistocene climatic stability in the west would have resulted in higher rates of speciation and lower rates of extinction than in the east, where for the most, Pleistocene climates would not have favoured Cape lineages. A more parsimonious hypothesis is that the more predictable seasonal rainfall of the west would have favoured non‐sprouting plants and that this, in turn, resulted in higher speciation and lower extinction rates. Both hypotheses are consistent with the higher incidence of rare species in the west, and higher levels of beta and gamma diversity there, associated with the turnover of species along environmental and geographical gradients, respectively. These rare species do not contribute to community patterns; hence, biological heterogeneity is uniform across the region. The weak topography pattern of diversity in the west arises from higher speciation rates and lower extinction rates in the topographically complex mountains, rather than from the influence of environmental heterogeneity on diversity.     

Agaricales found in the Godhavn area, W Greenland

The agaric flora of the Godhavn region (W Greenland 69°15'–69°30'N) was studied by the authors in 1967, 1970–72, and 1977. 1125 collections were made and 150 taxa were recognized. It was found that the fungus flora varied very much in the different seasons. The authors attempt to join their experience from studies in other arctic and alpine areas. In total, the check–list shows that there is a large degree of similarity between the agaric flora of the Godhavn area and that of the Alps and the Scandinavian mountains, while the similarity with the European lowland flora is less than earlier assumed. A bibliography of the relevant literature is appended.     

Growth, maturity and fecundity of wolffish Anarhichas lupus L. in Icelandic waters

Fecundity, maturity and the relationship between growth and maturity of common wolffish Anarhichas lupus were studied in Icelandic waters. A total of 788 female common wolffish were sampled in two areas: one in the relatively warm sea west of Iceland and the other in the colder sea east of Iceland. No difference was detected in fecundity of common wolffish between areas. The time from the onset of the cortical alveolus stage until spawning, was on average, 10 years in the east and 8 years in the west area. Common wolffish in the east area reached cortical alveolus stage, on average, at a greater age but similar size compared to common wolffish in the west area. Similarly, common wolffish started spawning, on average, at greater age and larger size in the east than in the west area. Common wolffish grew faster in the west than in the east area. Spawning common wolffish grew faster than common wolffish at the cortical alveolus stage in both areas. The relationship between growth and maturity for common wolffish in Icelandic waters appeared to be related to temperature, characterized by fast growth and early maturation in the west and slower growth and delayed maturation in the east.     

A Comparative Floristic Study on the Seed Plants of the East Side and the West Side of the Northern Gaoligong Mts . in Northwestern Yunnan,China

The differences in rainfall and temperature between the east and west sides of the northern GaoligongMts. leads to distinct differences in the plant diversity and floristic characteristics between the two sides . Recorded taxa on the east side include 1 475 native species and 192 varieties (or subspecies) belonging to 580 genera in 152 families and for the west side include 1 804 native species and 186 varieties ( or subspecies) belonging to 659 genera in 162 families . Based on the statistics and analysis of families, genera, and species, a comparative floristic study on the seed plants for the east side and the west side of the northern Gaoligong Mts. was carried out. The results are as follows: 1) The present flora on the east and west sides of the northern Gaoligong Mts . have the same floristic origins, but the relative contribution from these different sources has changed through time . The result is that the floristic similarity of families, genera, and species between the east side and the west side has decreased through time; 2) The floristic characteristic of seed plants for the west side has become more greatly influenced by tropical floristic elements than has that of the east side, and the influence by the temperate floristic elements has become less influenced on the west side but greater on the east side; 3) The flora of the west side is more closely linked with that of the eastern Himalayans than is the flora of the east side, and the flora of the east side is more closely linked with the other floras farther to the east. Owing to the obstruct of the Gaoligong Mts. ridge itself, it is seemingly difficult for the species interchange between the two sides of the northern Gaoligong Mts. ; 4) The ecological-geographical environment has made it more conducive to species conservation and the speciation on the west side than on the east side, so the west side is not only a refuge for some ancient floristic elements but also as a cradle of some new species.     

梵净山种子植物区系特征及植物地理学意义

梵净山为地处云贵高原向湘西丘陵过渡斜坡区,是武陵山脉的最高主峰,面积约为77 514 hm~2。该研究针对当地野生种子植物区系的问题,主要通过对种子植物科属种水平的地理成分、区系古老性、区系过渡性等区系特征进行了统计和分析。结果表明:(1)该区物种丰富、地理成分复杂,共有野生种子植物163科843属2 584种,中国特有种1 010种(含梵净山特有种46种),其中属的热带、温带地理成分比例相当,热带成分略占优势。(2)该区植物起源古老,保存有梵净山特有裸子植物梵净山冷杉、长苞铁杉、粗榧、水青树、伯乐树、领春木等大量古老树种。(3)该区与临近区系交汇、渗透现象明显、过渡性质突出,经初步确定以梵净山为典型分布边界点的植物共有120科197属288种,分别有103种、62种、87种、36种以梵净山地区为分布的北界、南界、东界和西界,即梵净山更多的阻碍了热带、亚热带植物的北迁和中国—喜马拉雅成分的东扩。(4)该区常绿树种与落叶树种并茂发育,热带成分与温带成分竞争激烈。因此,梵净山在中国植物区系甚至东亚植物区系中具有非常重要的意义。     

The galaxiid fishes of South America

Four galaxiid species in two genera are recognized and redescribed from the South American region, viz., Galaxias maculatus (Jenyns), G. platei Steindachner, G. globiceps Eigenmann, and Brachygalaxias bullocki (Regan). All of these species occur in Chile, but G. maculatus and G. platei occur also east of the Andean divide in Argentina, in Tierra del Fuego, and the Falkland Islands. The two species east of the Andes are regarded as having crossed the mountains from west to east. The galaxiids, together with Aplochiton (family Aplochitonidae) and Geotria (family Petromyzonidae), are regarded as southern circumpolar elements in the South American freshwater fish fauna, distinct from the group of species of Amazonian derivation (trichomycterids, Nematogenys, Diplomystes, Cheirodon , etc.) and distinct also from oceanic derivatives, either recent (atherinids) or ancient (serranids).     

Field and culture studies of species of Gelidium (Gelidiales,Rhodophyta) from their northern limit of distribution in Europe

Two species of Gelidium, provisionally referred to as G. pusillum and G. latifolium, are included in the Scandinavian flora and reach their northern limit of distribution on the Norwegian west coast. Small frond sizes due to adverse growth conditions, extreme phenotypic variability and lack of sexual reproduction make identification of specimens very difficult. Both species were isolated into unialgal culture and were compared with cultured strains referable to G. pusillum from Ireland and France. Temperature and salinity requirements and tolerance ranges were determined and discussed in view of distribution along the Norwegian coast. Little or no growth occurs below 9 °C, corresponding to a northern summer growth limit. On the Norwegian Skagerrak coast, low winter temperature rather than reduced salinity is the limiting factor.