bluuebunny/crossref_metadata_2025 huggingface dataset:
Mycorrhizal fungi of Betula spp.: factors affecting their occurrence
Authors: Mason P. A. , Wilson J. , Last F. T.
Published: March 2014

Synopsis

The production of fruitbodies of mycorrhizal fungi associated with Betula spp. in an experimental site was observed to occur in a pattern ordered in time and space. Certain species of Inocybe, Hebeloma and Laccaria and Thelephora terrestris appeared in the first five years after planting: they were followed by species of Leccinum, Cortinarius and Russula. Usually more fungi were associated with B. pendula than with B. pubescens. More toadstools of Laccaria tortilis developed in association with one clone of B. pubescens than with another which favoured instead the development of Inocybe petiginosa.

The idea of a fungal succession is supported by below-ground observation of mycorrhizas. Early- and late-stage fungi formed mycorrhizas on seedlings growing in sterile conditions whether inoculated with mycelia or spores. However, only early-stage fungi formed mycorrhizas in unsterile conditions.

The concept of succession is based on observations made when treeless sites were planted with Betula spp. However, experimental planting of seedlings into soil with intact roots of older trees with mycorrhizas of Lactarius pubescens resulted in mycorrhizas on the seedlings: but no mycorrhizas formed if the roots of the older tree had been severed. This suggests that the pattern or sequence of mycorrhizal fungi associated with seedlings regenerating within natural stands is likely to differ from that associated with Betula spp. colonizing previously treeless sites.
Insects associated with birch
Authors: Shaw M. R.
Published: March 2014

Synopsis

The entomology of birch in Britain (and to a lesser extent in Fennoscandia) is reviewed in broad ecological terms. In particular, the size of the associated fauna, the kinds of geographical distribution patterns seen for birch insects in Britain, birch defoliators, and the conservation needs of insects associated with birch in Scotland are considered. A closing section briefly outlines additional literature on the ecology of birch insects.
Genetics of plant-microbe nitrogen-fixing symbiosis
Authors: Machray G. C. , Stewart W. D. P.
Published: March 2014

Synopsis

A wide variety of plant-microbe nitrogen-fixing symbioses which include cyanobacteria as the nitrogenfixing partner exist. While some information has been gathered on the biochemical changes in the cyanobacterium upon entering into symbiosis, very little is known about the accompanying changes at the genetic level. Much of our present knowledge of the organisation and control of expression of nitrogenfixation (nif) genes is derived from studies of the free-living diazotrophKlebsiella pneumoniae. This organism thus provides a model system and source of experimental material for the genetic analysis of symbiotic nitrogen fixation. We describe the use of clonedK. pneumoniaegenes for nitrogen fixation and its regulation in the genetic analysis' of nitrogen fixation in cyanobacteria which can enter into symbiosis with plants. These studies reveal some dissimilarities in the organisation ofnifgenes and raise questions as to the genetic control of nitrogen fixation in symbiosis.
Lichens and plant nutrition
Authors: Millbank J. W.
Published: March 2014

Synopsis

The part played by lichens in the nitrogen economy of natural ecosystems is reviewed. The ability of some lichens to fix nitrogen and the consequent likelihood of an enhanced contribution is discussed, leading to the appreciation that release of nitrogen compounds from their thalli is a frequent characteristic of their growth and development, and of some nutritional benefit to associated plants.

Data on the contribution by the normal processes of growth, death and decay, to the combined nitrogen supply of those specialised habitats where lichens predominate or are frequent, are given. Such habitats are arctic and subarctic forest and tundra, and the Douglas fir forests of northwest U.S.A. The methods used for the estimation of the contribution of the lichens are outlined and details are given of recent and current studies of nitrogen movements by direct leaching during normal growth of nitrogen-fixing terricolous lichens in Finland and southwest Scotland. The latter study uses a laboratory apparatus to simulate field conditions in order to permit the use of atmospheres enriched with the heavy isotope of nitrogen, 15N.
‘Epidemiology’ of sheathing (ecto-) mycorrhizas in unsterile soils: a case study of Betula pendula
Authors: Last F. T. , Mason P. A. , Wilson J. , Ingleby K. , Munro R. C. , Fleming L. V. , Deacon J. W.
Published: March 2014

Synopsis

Sequential observations were made of the effects on root development of inoculating Betula pendula seedlings during propagation with sheathing mycorrhizal fungi, Amanita muscaria, Hebeloma sacchariolens or Paxillus involutus. After propagation, the seedlings were grown for two seasons in four different soils (two mineral soils and two peats) which were not sterilised.

While all inoculated seedlings had similar numbers of mycorrhizas at planting, numbers subsequently increased most rapidly with P. involutus and least rapidly with A. muscaria. From the end of the first season onwards, the uninoculated controls had as many mycorrhizas as seedlings inoculated with either A. muscaria or H. sacchariolens. These numbers were, however, usually exceeded on plants inoculated with P. involutus.

The mycorrhizas developing on the controls, and on seedlings inoculated with A. muscaria, were attributable after planting into the unsterile soils, to naturally occurring soil-borne inocula of species of Cenococcum, Hebeloma, Inocybe, Laccaria, Paxillus and Thelephora etc. Those developing on seedlings inoculated with P. involutus were all attributable to this inoculant fungus in the first year but, in the second year, the proportions decreased to 19—14%. With H. sacchariolens, at least 90% of the mycorrhizas in the two mineral soils and one of the peats (a sedge peat) were attributable in years 1 and 2 to the inoculant fungus. In the other peat (Sphagnum peat), the proportion of mycorrhizas attributable to H. sacchariolens decreased to 25% by the end of the first year and totally disappeared in the second.

The continued ability of H. sacchariolensto form mycorrhizas in a range of unsterile soils, to the virtual exclusion of mycorrhizas attributable to other fungi, is thought to be characteristic of fungi that occur early in mycorrhizal successions. In contrast,A. muscaria(a late-stage fungus), was unable to form mycorrhizas after inoculated seedlings were transferred from controlled axenic conditions to unsterilised field soils.

Two arbiters of root growth were measured—numbers of roots and their dry weights. Whereas inoculations with H. sacchariolens significantly decreased numbers in the latter part of the first season, they either had no effects on dry weights as in the mineral soils or significantly increased them as in the peats. In the second season, there was further evidence, sometimes contradictory, showing that inoculations can appreciably alter the structure of developing root systems.
The fauna of sandy beaches in Orkney: a review
Authors: Atkins S. M. , Jones A. M. , Simpson J. A.
Published: March 2014

Synopsis

The physical and biological characteristics of a variety of sandy shores in Orkney are described using transect data from 7 sites within Scapa Flow and 7 sites from the Mainland and North Isles. Shore profiles are described and discussed, shores ranging in length from 80 m to 1200 m. Median grain size of the sediments was generally between 180 and 300 μm (fine to medium grade sands) and the sediments were very clean. The fauna was dominated numerically by polychaetes and amphipods on all shores, Pygospio elegans, Capitella capitata and Bathyporeia spp. being the dominant forms; molluscs were notably insignificant on most shores. Tables giving the maximum densities of every species recorded together with the maximum densities of dominant species at each station on all shores are presentThe results are compared with a range of North European shores which comprise basically similar communities but with much higher population densities in Orkney. A site of unique interest at the Bay of Quoys, Hoy, is described and discussed.
Fisheries in the Orkney area
Authors: Mason James , Newton A. W. , McKay D. W. , Kinnear J. A. M.
Published: March 2014

Synopsis

Fishing has long played an important part in the economy of Orkney. Local vessels are all small, and fish predominantly inshore for shellfish. Demersal and pelagic fish are abundant in the offshore waters around Orkney, but these exposed waters can be fished only by large vessels from more distant ports, so that few fish are landed in the islands.

Gadoids, especially haddock, cod and whiting, form the bulk of the demersal fish caught at Orkney. Stocks of all three are giving cause for concern, with declining spawning stock biomass and reduced recruitment. With the coming of processing, more local landing of demersal fish might occur. The closure of the herring fishery in 1977 was followed by a great expansion of mackerel fishing, but with the lifting of the ban west of 4CW in 1981, herring catches have once again become valuable. Because of fishing pressure, landings of both species are subject to quota restrictions.

In recent years, the traditional fisheries for lobsters and crabs have been supplemented by a new fishery for scallops. Lobster stocks are now under some pressure. Conditions around Orkney appear suited to farming filter-feeding bivalve molluscs, and culture and marketing of Pacific oysters has started.
Orkney's seabirds and coastal otters
Authors: Reynolds Peter
Published: March 2014

Synopsis

The size and distribution of Orkney's breeding seabird populations are relatively well known, with cliff-nesting species having been monitored annually since 1976. Conditions for these monitored species appear to be less favourable now than they were at the beginning of the study.

Nationally significant populations of seaducks and waders winter in Orkney. With exceptions, the population size, distribution and ecology of these birds is only poorly understood.

Otters appear to be widespread; however, spraint surveys suggest that these animals may not be as numerous in Orkney as they are in Shetland, the Western Isles and Highland Region.
Food and drink in Scotland: the economic base
Authors: Houston G. F. B. , Smith L. D.
Published: March 2014

Synopsis

While food and drink expenditure per head in Scotland is much the same as in the rest of the U.K., primary food production is at a relatively higher level, food processing is slightly less important and alcoholic drink production very much higher. Food production in Scotland is almost 80% of food consumption but probably less than 40% of what we cat has remained within the country all the way from farm or sea to the Scottish consumer. Over half of Scottish consumers' food expenditure goes to processing and distribution and around a quarter to the farming and fishing industry; the balance is spent on imports. Farm output has roughly doubled over the past 30 years while farm prices (relative to other prices) have roughly halved. In recent years food manufacturing has regained the production levels of 1979 while other manufacturing has declined by over 10%. The alcoholic drink industry has suffered much more from the recession. The relatively stable domestic demand for food conceals changes in the pattern of that demand and the development of all sections of the Scottish food and drink economy depends on their adapting to these changes as well as exploiting opportunities to replace imports or develop export markets.
Scotland's land and soils
Authors: West T. S.
Published: March 2014

Synopsis

The range of foodstuffs that can be produced by Scottish agriculture depends chiefly on the nature of the soils and the prevailing climate. The landform of Scotland and some of its physical features are discussed in terms of its geology, and the nature of its present-day soils in relation to parent materials is summarized. The agriculturally useful soils have been mapped, inventoried and characterized by the Soil Survey of Scotland and other departments of the Macaulay Institute for Soil Research. The limitations imposed by the soils, their geographical latitude, altitude, aspect, slope, the prevailing weather in their locality, etc., are taken into account in the Land Capability for Agriculture (LCA) assessment. Examples are given of several physical and chemical characteristics which are dominant in Scottish soils and which are of particular significance to the production of foodstuffs.
The sea and fresh waters
Authors: Mclntyre A. D.
Published: March 2014

Synopsis

The pattern of the current Scottish sea fishery is described in terms of landings, value and species. The contribution from fresh water and from aquaculture is also outlined and the possibilities of distant water fisheries noted. The stability of the resource base is examined, and the effects of pollution assessed. For the future of fisheries, the importance of adequate management arrangements coupled with an understanding of how fishing pressure and fluctuations affect the stocks is emphasised.
Horticultural food crops
Authors: Taylor C. E.
Published: March 2014

Synopsis

In Scotland horticultural food crops occupy about 1·4% of the tillage land, and contribute about 4% of the total Scottish agricultural output. Climate, soil type and factors such as distance to markets and availability of labour have influenced the location of horticultural crops. This has changed with time, particularly because of the influence of the processing industry. Soft fruit production (3,630 hectares), with raspberries being the dominant crop, is concentrated in the Tayside region; more than 90% of the raspberry crop is processed by pulping (for jam, etc.), freezing or canning. Vegetable production (6,130 hectares) is somewhat more dispersed from the Border region to the Moray Firth; more than half the total area is occupied by peas for canning and freezing. Glasshouse production of tomatoes is now only 25 hectares located mainly in the Clyde Valley.

The future for Scottish horticultural food production will continue to be influenced by the requirements of the processing industry, but there is also an increasing outlet for fresh fruit and vegetables in supermarkets. Expansion of the production of horticultural food crops in Scotland depends on the ability of the industry to meet market demands in terms of quality and continuity of supply. Increasing reference to the need for an improved British diet may stimulate the consumption of fruit and vegetables on the home market and there continue to be opportunities for increasing the export of processed and fresh produce. Scotland has the land resources, crop production expertise and processing and marketing facilities to respond to these opportunities.
The Scottish Research Institutes
Authors: Hamilton L. P.
Published: March 2014

Synopsis

The organisations concerned with agricultural and fisheries research and development in Scotland are outlined and the institutional and funding arrangements are explained. The role of DAFS is presented in an AFRS context and the operation of the customer/contractor principle discussed. The overall objective is to improve the efficiency of plant and animal production in northern Britain, taking account of social, environmental and welfare considerations. Flexibility to respond to changing requirements is an important factor. The remits of the institutes and colleges are set out and are appropriate to the major agricultural sectors. The integrative and collaborative strengths of the commissioned work are illustrated with selected examples of relevance to produce yield, food quality, shelf-life and human diet. Advice on research and development priorities and the allocation of budgets is provided by the new Priorities Board and there is close liaison between DAFS, MAFF and AFRC to ensure co-ordination of effort.

Reference is also made to the main elements of the fisheries research programme. Revised review procedures to monitor research progress and respond to changing industry needs are described. The paper concludes by examining the problems arising from reduced funding.
The Scottish universities
Authors: Morrison William R.
Published: March 2014

Synopsis

Only two Scottish universities are directly involved in education in the food area. At Strathclyde students can read for a BSc with honours in Food Science, and for an MSc in Food Science and Microbiology. At Heriot-Watt students can read for a BSc in Brewing, a BSc with honours in Brewing and Microbiology or Biochemistry, and for an MSc in Brewing. Food education in the universities is almost entirely dependent on UGC funding, and sponsorship is rare except for students from overseas. The food industry in Britain has a poor record for supporting university education. In recent years the centralisation of the activities of large manufacturing companies in the South has reduced career prospects for graduates in Scotland. Although few in number, the staff at Strathclyde and Heriot-Watt have earned a high reputation for their research, ranging from basic to applied studies. A significant proportion of doctoral students are from overseas countries, as are most MSc students. Funding for research has always been difficult, except for support from the brewing and distilling industries. However, moves to reorganise and rationalise publicly funded support for R & D in the food and drinks industry are beginning to have an effect, and in some respects the prospects for university food research have never been brighter. There are, however, several unsatisfactory aspects in this situation. Current government policy is to cut-back university funding to the detriment, inter alia, of staffing for food science, thereby restricting the number of research supervisors in a declared area of national priority! This is also harmful in that staff can no longer handle small enquiries and problems from industry, so impairing relations which are already tenuous. Finally, inability to recruit replacement and new staff is preventing the universities from leading the way into new applications of molecular biology and biotechnology in foodstuffs.
The brewing industry
Authors: Slaughter J. C.
Published: March 2014

Synopsis

At the moment Scotland has of the order of 15 commercial breweries and these represent a range of production capacities from under 100 barrels per year for the smallest one-man operations to over 2–5 million barrels per year for the largest modern plant. All the main beer types, ale, lager and stout, are produced and lager is a more important component than for the United Kingdom generally. There is 1 Scottish-based United Kingdom national brewer and production is also carried out in Scotland by 3 other of the United Kingdom nationals. These 4 account for most of the beer produced with the rest contributed mainly by 2 Scottish regional brewers and 1 brewery owned by an English regional brewer.

The essentials for beer production, water, malt, hops, yeast, finings and energy, can all be had from Scottish sources with the exception of hops and finings. The last decade has seen a massive increase in the area of barley grown in Scotland and along with this has gone a large increase in malting capacity, so that the supply situation for malt has been transformed. However, brewers may still buy malt from other sources to obtain specific properties or to ensure a more stable blend. In addition, brewers commonly employ a certain amount of unmalted cereal adjuncts, e.g. barley, maize, wheat, and sugar to increase economically the strength of their worts. In cases where beer is meant to keep longer or travel further than the traditional ales, brewers use a variety of filter materials such as cellulose and kieselguhr, stabilizing aids such as PVPP and alginates, and in many modern plants industrial enzymes are used as remedial aids and as established items in the production schedules. None of these quantitatively minor materials seem to be produced by Scottish companies.
Introduction: deep-sea benthic investigations
Authors: Allen J. A.
Published: March 2014

For the last twenty-five years the pace of international deep-sea benthic investigations has been gaining momentum, first as a genuine basic scientific exploration of the largest unknown area of the Earth's surface and later as a place man might exploit for the disposal of high energy radioactive wastes and to mine for manganese.
Studies of a benthic time series: reproductive biology of benthic invertebrates in the Rockall Trough
Authors: Tyler P. A.
Published: March 2014

Synopsis

The reproductive biology of a wide variety of deep-sea echinoderms from the northeast Atlantic has been examined. Time series samples of asteroids, ophiuroids, echinoids and holothurians are available from Station “M” and the Scottish Marine Biological Association's Permanent Station in the Rockall Trough and from opportunistic sampling in other areas of the northern Rockall Trough. Examination of these time series samples has established three main reproductive patterns in these taxa and one example of protandric hermaphroditism. The dominant reproductive pattern is the aperiodic production of relatively few large eggs usually in excess of 600μm diameter. Although the oogenic pattern is similar in most of these species, the follicle cell distribution and breakdown of relict oocytes vary considerably, particularly at family level. A second reproductive pattern is the production of numerous small eggs c. 100μm diameter, indicative of planktotrophic development. The five species exhibiting this pattern show intra- and interspecific synchrony of egg production with a proliferation of young oocytes in February to April of each year, vitellogenesis during summer and autumn and a synchronous spawnout in January–April of each year. In the apparent constant conditions of the deep sea, this synchrony of reproduction is related to the rapid descent of surface primary production. Two rarer reproductive patterns observed are the production of intermediate sized eggs (c. 300–400μm diameter) suggesting the formation of a lecithotrophic larva, and lastly a single case of protandric hermaphroditism, and the subsequent production of a large egg. In none of the species examined have we found any evidence of brooding. The variation in the reproductive pattern of individual species is discussed in relation to the constancy of the physico-chemical environment of the deep-sea.
The dynamics of organic production in the Rockall Channel area
Authors: Zeitzschel B.
Published: March 2014

Synopsis

For the onset of the phytoplankton spring bloom in temperate waters, the irradiance, the concentration of accumulated nutrients and the stability of the water column are of great importance. The “new” production in spring is produced mainly by chain forming diatoms.

The dissipation of the spring bloom is due to nutrient depletion in the stabilised surface layer, loss of cells by sinking and grazing by herbivorous zooplankton. After the nutrient concentration is lowered, the rate of production will depend primarily on the rate of replenishment of nutrients. In open ocean environments we find “regenerated production” which is due to exudated and excreted nutrient salts e.g. ammonium. The dominating group of phytoplankters are small flagellates. It is argued that a substantial part of the phytoplankton standing stock in spring is lost from the euphotic zone due to direct sinking of cells or accelerated sinking of cell-aggregates. It is postulated that faecal pellets of micro- and mesozooplankton are retained and recycled in the mixed layer, whereas macrozooplankton faecal strings transport a considerable amount of organic matter to the benthal.
Shetland and the building of the Sullom Voe crude oil terminal
Authors: Fenwick M.
Published: March 2014

The Sullom Voe crude oil terminal has already been almost seven years in the making. I would like to take you all back through those seven years to the halcyon days before Shetland found herself face to face with the unveiling of a geological event which occurred millions of years ago.

Imagine yourself a Shetlander. You are a member of a community of about 17,000 independent, resourceful folk, who had only just stabilised their traditional fishing/agricultural/knitting economy and their population after a century of decline. During that century, or as much of it as you have lived through, you have seen friends and relatives leaving on the 'Clair' with monotonous regularity bound for any place between Aberdeen and Australia. You may have lost some of those friends and relatives on whalers in the wastes of the South Atlantic. You have seen crofts left to go derelict and to waste, and most of your able bodied menfolk having to leave the islands in order to find gainful employment. Latterly, you have just been successful in combating the proposals of the Wheatley Commission to absorb the islands into a Highland Region.
Anti-oil pollution strategy in Sullom Voe—environmental considerations
Authors: Syratt W. J. , Richardson M. G.
Published: March 2014

Synopsis

This paper describes briefly the history behind oil pollution contingency planning for Sullom Voe. It describes in detail the environmental factors which have been considered when drawing up the Sullom Voe Harbour Oil Spill Plan. These factors are:

1. The nature of the sea zones within the Oil Spill Control Area.

2. The nature of the coastline within the Oil Spill Control Area.

In both cases accessibility of the various zones, and how this will affect contingency planning, is discussed.

3. Wildlife and conservation interests including: (a) ornithological interests; (b) mammals; (c) inshore fisheries; (d) salt marshes and soft mud shores; (e) houbs and other sensitive shallow water areas; (f) Sites of Special Scientific Interest SSSI's and Nature Reserves; (g) secondary beach structures; (h) sand amenity beaches and (i) other amenity areas, e.g. harbours.

Finally the strategy, based on the factors summarized above, and its effectiveness in the light of an oil spill, is discussed.
Monitoring seabirds in Shetland
Authors: Richardson M. G. , Dunnet G. M. , Kinnear P. K.
Published: March 2014

Synopsis

The programme for ornithological monitoring in Shetland has concentrated on selected species of cliffnesting seabirds and inshore waterfowl. Sample study sites throughout Shetland have been selected and standard counting methods derived. These have taken account of factors such as logistics and accessibility, the effects of weather and observer error and of the seasonal and diurnal variations in the numbers of birds.

Changes in seabird and waterfowl numbers between 1975–79 have been observed. These, with the exception of the bird mortality following the Esso Bernicia oil spill, have been attributed to natural variation. From the scale and local differences between these as yet short-term observations, estimates are presented of the minimum percentage change required in either numbers of birds or their nests before such natural variation is exceeded.

The problems of interpreting changes in numbers are discussed.

The number of dead birds picked up in Sullom Voe after the Esso Bernicia spill corresponded closely to that estimated from the monitoring counts before and after the incident.
The macrobenthos of Sullom Voe
Authors: Addy J. M.
Published: March 2014

Synopsis

The macrobenthos of Sullom Voe was investigated by grab sampling in 1976, 1977 and 1978. These surveys have provided data for future comparisons and have enabled a description to be made of the natural soft bottom macrobenthos of Sullom Voe in terms of species composition and abundance.

The most common species encountered were Thyasira flexuosa, Glycera ?alba, Nephtys hombergi, Myriochele oculata and Rhodine gracilior, which are widely distributed throughout Sullom Voe. Other species such as Owenia fusiformis and Prionospio malmgreni were restricted to the outer regions whilst Scalibregma inflatum and Venus ovata were largely confined to the inner stations. The most intensive sampling was carried out around the proposed ballast water discharge site and in this area it was possible to define four faunal areas corresponding to the sediment characteristics. This subjective analysis based on species distribution maps was borne out by multivariate ordination and classification of the data.

The macrobenthic diversity of Sullom Voe is compared with other coastal areas such as Milford Haven and some Scottish sea lochs. Sullom Voe supports a relatively diverse community which in terms of species richness compares with the benthos of other sheltered, undisturbed areas elsewhere in Scotland.
The physical and biochemical condition of Modiolus modiolus (L.) in selected Shetland voes
Authors: Comely C. A.
Published: March 2014

Synopsis

1. A general survey of the sub-tidal populations of Modiolus modiolus (L.) to a depth of 18 or 21 m was carried out in five Shetland voes, with particular emphasis in Sullom Voe. Estimations of density distribution and growth rate were made.

2. Commencing in June 1976 samples were collected at three-monthly intervals from two sites in Sullom Voe, and from one site in Cat Firth in 1977, to investigate seasonal variations in flesh and biochemical content. The data indicate that Shetland Modiolus are generally similar in their biology to those from Scottish lochs, and are liable to considerable variation between and within populations, with groups responding to environmental variations of very local extent.

3. A list of animals found associated with Modiolus and their byssus complexes is given. As no effort was made to collect the fauna systematically or quantitatively, the list is not comprehensive.
Genetics of gametophyte development
Authors: Hickok Leslie G.
Published: March 2014

Synopsis

Fern gametophytes provide unique opportunities for the investigation of various aspects of physiology, genetics and development. Past genetic studies of gametophytes have primarily involved investigations of variegation and radiation-induced plastid aberrations. Two studies have utilised the gametophyte generation to develop screens for specific types of mutations. The considerable natural variation that exists in gametophyte development has not been investigated genetically. Genetic studies can provide needed information regarding basic aspects of development. A selection system with broad applicability has been developed to isolate gametophyte mutations that confer resistance to growth regulators. An example of the use of the screen with abscisic acid is given and preliminary characterisations of some of the mutants are presented.
Gametogenesis: the playground of the developmental cytologist
Authors: Miller C. C. J. , Duckett J. G. , Kirkham B.
Published: March 2014

Synopsis

Developmental ultrastructural studies have led to major advances in our understanding of key questions ranging from the causal basis for the alternation of generations and the role of the cytoskeleton in cellshaping processes to the phylogeny of archegoniate plants. Oogenesis is characterised by profound nuclearcytoplasmic interactions accompanied by striking changes in the egg mitochondria and plastids. At fertilization, egg penetration is a physical process and the plastids from the spermatozoids are excluded from the egg. Considerable dissimilarity between the shapes of the biflagellate spermatozoids ofLycopodiumandSelaginellaunderlines their ancient separation. Equally striking differences in spermatozoid architecture argue against any direct phyletic link between heterosporous and homosporous ferns. Taxonomic variations between the spermatozoids of homosporous ferns suggests blepharoplast morphology to be a potentially rich source of new systematic data. Whilst there is general agreement that the multilayered structure is a cytoskeletal alignment system, a proposed shape-generating system situated near the nuclear envelope, which provides the force necessary for spermatozoid morphogensis, has not yet been identified. New fixation procedures have revealed hitherto overlooked filamentous elements associated with the nucleus. Whereas tests for actin were negative, immunoblotting suggests that these contain the intermediate filament protein antigens.
Physiology and biochemistry of pteridophytes
Authors: Raven John A.
Published: March 2014

Synopsis

The biochemical characteristics of pteridophytes firmly ally them with other Tracheophyta, with Bryophyta and with the class Charophyceae of the algal division Chlorophyta. Pteridophyte sporophytes, like the sporophytes of other terrestrial Tracheophyta, generally have the attributes of homoiohydric plants. All gametophytes are poikilohydric. Many gametophytes, and some sporophytes, are desiccation tolerant.

Quantitative comparisons between pteridophyte sporophytes and the sporophytes of other tracheophytes show that there are probably no systematic differences between the efficiency of important processes: examples are the quantum yield of photosynthesis, and the water use efficiency of organic matter accumulation, in the (mainly) C3 pteridophytes relative to other C3 tracheophytes. By contrast, the potential rales of physiological processes, as indicated by the conductance of photosynthetic (C3) carbon assimilation, and of water movement in the xylem, are generally towards the low end of the range for terrestrial tracheophytes. These low conductances restrict the maximum specific growth rate of pteridophyte sporophytes to rates lower than those found in annual angiosperms. Constraints imposed by the pteridophyte life cycle may have limited the capacity of pteridophytes to function in nature as annuals, and thus have reduced the selection pressure for high conductances (e.g. by a more widespread occurrence of vesseles in xylem of pteridophytes).
Some aspects of agamospory in ferns—the Braithwaite system
Authors: Walker Trevor G.
Published: March 2014

Synopsis

The Braithwaite system of agamospory is reviewed. The few ferns having this system are very diverse, both systematically and in their behaviour. It is concluded that this type of agamospory has arisen independently several times by different routes.
Action and phylogeny of antheridiogens
Authors: Schraudolf H.
Published: March 2014

Synopsis

Evolution of new forms of organisms must be accompanied by evolution of the informational processes which regulate the development of these new forms. During plant phylogeny, products of metabolism have become phytohormones through the evolution of receptor molecules. Although nothing is known about these receptor molecules, it is suggested that the schizaeaceous ferns are the most primitive group in which a gibberellin-like substance acts as a signal for morphogenesis, and that their antheridiogen pheromones, which stimulate antheridium formation and spore germination, are the ancestors of the gibberellin hormones which influence seed plant development. Chemical and biological evidence for this suggestion is discussed.
Spore filaments in the ant-fern Lecanopteris mirabilis—an alternative viewpoint
Authors: Walker Trevor G.
Published: March 2014

Synopsis

Spores of the ant-fern Lecanopteris mirabilis (C.Chr.) Ching are discharged in groups of 16 spores per sporangium and are held together by long filamentous outgrowths of their surface. It is contended that the filaments are not primarily an adaptation to ant-dispersal, as has been suggested, but maintain genetic variability by promoting intergametophytic mating of the prothallial populations produced as an outcome of the spores being held together in clusters.
Rusts and other fungal parasites as aids to pteridophyte taxonomy
Authors: Bennell Alan P. , Henderson Douglas M.
Published: March 2014

Synopsis

The fungal parasites of ferns and their allies have been largely neglected, both by pteridologists and mycologists. Greater interest is advocated in the light of recent studies of patterns of host specificity of such fungi on angiosperms, which have provided valuable insights into the systematics of these hosts. Our knowledge of the major groups of fungi reported as parasites of pteridophytes is reviewed, and their potential contribution to host classification and phylogeny discussed. The relationship of the Uredinales (rust fungi) and their fern hosts is examined in detail.
Interaction between bracken and its insect herbivores
Authors: Lawton J. H. , MacGarvin M.
Published: March 2014

Synopsis

Bracken in Britain is a host for 27 species of insect herbivores, with a further 11 species that either feed below ground (and are poorly studied), or appear to be only rarely associated with the plant. A typical site in northern England has an average of 15–16 of these species in any one year. Compared with perennial herbaceous angiosperms with similar wide distributions, bracken is not noticeably depauperate in the number of insect species that feed upon it. Bracken in others parts of the world is attacked by a wide variety of insects, with more species present in the geographical areas where bracken is most common.

The ‘feeding niches’ of some of these insects are reviewed. Most are very rare relative to the biomass of their host plants, probably because of the impact of natural enemies; the effect of most of the insects upon their host-plant is consequently negligible.

Reverse effects, of host-plant upon the insects, are subtle but poorly understood. Experiments to elucidate these effects are briefly outlined.
Studies on the physiology and propagation of the ostrich fern, Matteuccia struthiopteris
Authors: Prange Robert K.
Published: March 2014

Synopsis

The effect of photosynthetic photon flux density (PPFD), water, temperature and nutrition on frond emergence, vegetative frond production, fertile frond production, vegetative propagation and dormancy is examined. Ostrich fern plants will not break winter dormancy until they have received a minimum amount of cold exposure below a base temperature which is above 5.8°C and may be as high as 20°C. After the plants have received their chilling requirement, vegetative frond emergence does not occur until temperatures at or above ca. 9.3°C are reached. Percent germination and rate of emergence increases up to ca. 24°C. Photosynthetic photon flux density, water availability and mineral nutrition can affect both vegetative and fertile frond production but water availability appears to be the most critical. A mild water stress of −0.15MPa can have significant effects on water status and gas exchange in fronds. Sporophyte plants for field production have been produced vegetatively from detached meristems occurring naturally on the rhizomes, and through fertilization of axenic gametophytes.
Photoresponses in cell cycle regulation
Authors: Wada Masamitsu
Published: March 2014

Synopsis

The cell cycle of a protonema of Adiantum capillus-veneris L. cultured under continous red light is controlled by two photoreceptors: phytochrome and a blue and near-ultraviolet light-absorbing pigment (Pb−nuv). Irradiation with blue light, which is absorbed by Pb−nuv located in the nuclear region, shortens the duration of the G1 phase, but does not affect other phases. On the other hand, phytochrome has two roles in cell cycle regulation. Irradiation at the beginning of the G1 phase with far-red light, which is absorbed by phytochrome located throughout the entire protonema, lengthens the duration of the G2 phase. Phytochrome also arrests the cell cycle at the G0 phase under continuous red light, and, after red light irradiation, returns to the G0 phase any cell cycle which has already been started by dark incubation, unless the cell cycle has progressed to a ‘point of no return’ which coincides with the beginning of the S phase. Photoregulation of the cell cycle is summarised in Figure 4.
Geography and ecology of Indian clubmosses
Authors: Pandey P. S.
Published: March 2014

Synopsis

Observations are made on the geographical and ecological distribution of the clubmosses (Lycopodiuni) in India, and their habitats and reproductive abilities.

The requirements of clubmosses in India for conditions of good illumination plus habitats of low vegetational competition pressure are probably the most important factors in restricting the species to either well lit forest canopies in the tropics or to open, treeless hillsides in the temperate zone. In the former, the epiphytic habit has become important. In the latter, the terrestrial habit has been exploited. Reproduction in the epiphytes is by spores, which establish in mossy epiphytic cushions. Reproduction in the terrestrial species is either by spores which establish in mosses or in areas opened by erosion and landslides, or by bulbils. The latter achieve a useful, local, additional means of reproduction in climates where, because of low temperatures, the rates of growth can be very slow.
Speciation and hybridisation in North American quillworts
Authors: Taylor W. Carl , Luebke Neil T. , Smith Mary B.
Published: March 2014

Synopsis

Species of Isoetes in northeastern North America may have evolved through hybridisation and allopolyploidy. Evidence for natural hybridisation was obtained from overlapping distribution patterns, abortive and polymorphic spore formation, chromosome numbers ranging from diploid to decaploid, and additive enzyme electrophoresis profiles. The ease with which hybrids form in culture supports the hypothesis that natural hybrids occur and that hybridisation could be involved in the evolution of new species.
Ecology and geography of hybridisation in British and Irish horsetails
Authors: Page C. N. , Barker Marian A.
Published: March 2014

Synopsis

Hybridisation inEquisetumin Britain and Ireland is examined in respect of the exceptional numbers of hybrids present, their geographic and ecological distribution, their formation and subsequent spread.

It is concluded that the moist oceanic climate and relative paucity of competing species in the British and Irish floras in post-glacial time have created uniquely favourable conditions for the formation and subsequent success of hybrid horsetails, promoting both the short-term persistence of weaker hybrids, and the extremly long-term persistence of others.

The taxonomic inter-relations of parental combinations which have formed ecologically successful hybrids are discussed.
Nucleic acid comparisons as a tool in understanding species interrelationships and phylogeny
Authors: Stein Diana B.
Published: March 2014

Synopsis

Studies comparing nucleic acids of some pteridophytes with others or with angiosperms are briefly reviewed. Amongst the pteridophytes, the fern genus Osmunda has been most thoroughly investigated by DNA sequence comparisons. O. cinnamomea, O. claytoniana, and O. regalis have equally diverged DNA sequences suggesting that evolutionary lines leading to these three species separated at about the same time; taxonomic placements that link any two of the three species closely together are, therefore, inappropriate. DNAs of the hybrid fern, O. × ruggii, were examined by analysis of restriction fragments of chloroplast DNA and by nuclear DNA hybridisation. The results support the previously proposed parentage.
Diversification of early ferns
Authors: Galtier Jean , Scott Andrew C.
Published: March 2014

Synopsis

A review of current knowledge of early fern evolution is presented including new data on age, morphology and anatomy with two diagrams summarising the early diversification of cauline and foliar anatomy and of the reproductive structures. The relationships and even the attribution of some Devonian taxa to the ferns is questioned whilst most of the Carboniferous coenopterids are considered indisputable ferns, some of them being related to modern filicaleans. The discovery, in the Lower Carboniferous of Scotland, of diverse annulate filicalean sporangia suggests an earlier (Tournaisian) radiation of true ferns than was previously assumed.
A Malesian viewpoint
Authors: Holttum R. E.
Published: March 2014

Synopsis

Comments are presented on the continuing need for a better taxonomy of ferns as a basis for experimental studies of all kinds; some aspects of the ecology of Malesian ferns are also considered.
Population dynamics of woodland Dryopteris in Britain
Authors: Willmot A.
Published: March 2014

Synopsis

Five mixed populations of Dryopteris dilatata and D. filix-mas have been studied in deciduous woods near Derby, England. It has been shown that in selected populations of each species, the plants were significantly clumped. It has also been shown that small plants of each species in all populations tended to grow amongst bryophytes, whilst larger ones grew in a wider range of habitats. All populations of D. dilatata showed an excess of small, sterile plants over larger, fertile ones. All but one of the D. filix-mas populations showed an excess of large, fertile plants over small, sterile ones, while the remaining one showed roughly equal numbers of large, fertile plants and small sterile ones. The population dynamics of two populations of each species have been studied so far over two seasons. This has shown that plants may increase or decrease in size or remain the same size between years. Mortality has been shown to be very size-specific in that smaller plants have a much lower chance of survival. Colonisation by new plants was mostly in bryophytes near established plants. The significance of these observations for the population dynamics of the species is discussed.
Hybridisation in Costa Rican Polystichum
Authors: Barrington David S.
Published: March 2014

Synopsis

Polystichum muricatum hybridises with both P. polyphyllum and P. speciosissimum on the Cerro de la Muerte in Costa Rica. Both hybrids are intermediate between their two parents in most of the assessed characters. True indusia, which are fully developed in P. muricatum, vestigial in P. polyphyllum, and absent in P. speciosissimum, are intermediate in mean development in both hybrids. However, one sorus is likely to have either a fully-developed indusium or a vestigial indusium. False indusia are characteristic of P. speciosissimum, but are vestigial to absent in its hybrid with P. muricatum. False-indusium development appears to behave as a recessive trait in the interaction of P. speciosissimum with P. muricatum.

Environmental disturbance has played a major role in the development of hybrids in Costa Rica. Mixed populations of the parent species are more common in disturbed terrain than in pristine areas, and hybrids are found only in disturbed terrain; this suggesting that disturbance promotes hybridisation.
Ecological aspects of distribution and speciation in Old World tropical ferns
Authors: Parris B. S.
Published: March 2014

Synopsis

The number of fern species in various countries in the Old World tropics is examined and explanations for very rich and very poor fern floras are given. Borneo and New Guinea are the two richest areas, with an estimated 1000 and 2000 species respectively; the difference in number is probably due to the much greater area of land at high altitudes in the latter. Aspects of geographical and ecological speciation in the genusGrammitiswithin New Guinea are discussed, and the means by which such speciation may have been promoted are outlined.
Ecology of some neotropical hybrid pteridophytes
Authors: Gómez-P. Luis D.
Published: March 2014

Synopsis

Information on the ecology of tropical hybrid pteridophytes is extremely scarce, and, indeed, a very small number of hybrids are known in these habitats.

Some questions and examples relating to this problem are posed, as seen in the New World tropics.