Hypotheses concerning diaspore behaviour are presented. It is suggested that in many plants, dispersal strategy involves alternative agents (2 or more vectors) and combination of distances. The hypotheses are substantiated by data compiled from observations of dispersal modes and mechanisms in herbaceous plant species of the Middle East. Two special modes, heterocarpy and amphicarpy, represent complex strategies with different propagules on the same individual. Amphicarpy resembles cryptophytic life-form in many respects. In several other cases the same propagule can be dispersed for various distances by a single vector or through alternative modes. Combination of long-range, short-range, and in situ dispersal is described for many species; Compositae of Turkey serve as a study case of the possible abundance of this strategy.

Several combinations of different vectors that can distribute the same diaspores, alternately or successively, are recorded. It seems that the combination of wind and temporary water currents is quite common in our region. Cruciferae of Israel serve as a study case of the possible abundance of this strategy and its various combinations. It is concluded that dispersal strategies with alternate modes are typical of many herbaceous species and probably adopted by most angiosperms. The one-to-one conservative relationships between adaptation and mode, mechanism and agent, are rather misleading. An adaptation or a syndrome should not be rigidly defined as they may function in more than one way. Often, the alternate mode can be more effective than the mode attributed to that particular syndrome. By such strategy a plant can better guarantee its distribution in space.

Photogeneration of singlet oxygen molecules (1O2), their vibrationally excited state and dimols (1O2)2 has been shown by measuring photosensitised delayed luminescence in pigment-containing media. All singlet oxygen species are formed as a result of energy transfer to O2 from triplet pigment molecules. Monomeric pigment molecules are the most efficient singlet oxygen generators. The 1O2 quantum yields are 40–80% in aerobic solutions of monomeric chlorophylls and pheophytins. Pigment aggregation causes a strong decrease in singlet oxygen production. The 1O2 quantum yield in chloroplasts has been estimated using literature and experimental data on formation of the chlorophyll triplet states in the photosynthetic apparatus. The most probable value is 0.1%. One of the major sources of singlet oxygen is likely to be the triplet states of newly formed pigment molecules which are not quenched by carotenoids and can be detected by measuring low-temperature pigment phosphorescence. Quenching of singlet oxygen by the thylakoid components has been analysed and the 1O2 lifetime estimated. The data suggest that carotenoids and chlorophylls are the most efficient physical 1O2 quenchers and the 1O2 lifetime is about 70 ns in thylakoids. The quantum yield of 1O2-induced pigment photodestruction was estimated to be about 10−6–10−5. This value is close to the quantum yield of chlorophyll photobleaching experimentally observed in aerobic suspensions of isolated chloroplasts. The intensity of pigment phosphorescence at 77 K correlates with the rate of chlorophyll photobleaching in plant materials. The data suggest that 1O2 generation by the pigment triplet states is the most likely reason for chloroplast photodamage. The intensity of pigment phosphorescence can be used as an index of the degree of plant photo-oxidative stress.

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.

The occurrence of a population of the spionid polychaete Marenzelleria viridis (Verrill 1873) in the middle reaches of the Tay Estuary is reported. This is a new British and European record of a North American species, and its principal characteristics are described and compared with earlier accounts. Size frequency analysis of the population showed it to be dominated by large animals from July 1984 to May 1986. The population matured coelomic gametes during winter 1985–86 and spawned in March 1986 to produce a heavy settlement in May, which subsequently grew rapidly. The distribution of M. viridis in relation to other species, sediment and other ecological parameters is described from a single survey of the Invergowrie Bay mudflats. Marenzelleria population densities of up to 1500 m 2 were negatively correlated with all other species of a low diversity macrofaunal community dominated by predatory polychaetes and filter feeding bivalves. Marenzelleria was abundant down to sediment depths of 20–30 cm. The significance and origin of this population is discussed.

An account is given of the distribution of the sand deserts in Iran, Afghanistan and Pakistan Baluchistan, where they cover large surfaces on the plains at low and medium altitudes. Climatologically they differ considerably from each other with respect to winter temperatures, but the latitudinal sequence is obscured by elevation effects. About one half to one third of the species are strict psammophytes; structurally they are the most important components of the different plant communities and in mobile sands usually no other plants occur. Their phytogeographical and taxonomic relationships are discussed in detail and attempts made to relate the distributional patterns to certain ecological factors. 66% of the species are truly Irano-Turanian, 23% are endemics, mostly derivatives of Irano-Turanian species, 10% are Saharo-Arabian and 7% are biregionals. Further aspects pointed out are the representations of life forms of families and genera. The results in the deserts studied give support to the concept of a coherent Irano-Turanian floristic region. The southern deserts form a sub-unit of their own, characterised by high numbers of endemics, some intruding Saharo-Arabian species and an absence of several otherwise common Irano-Turanian species.

The forest zone of West and Central Africa comprises the coastal and adjacent inland regions bounded the semi-deciduous forests in the west and the equatorial forests in central Africa and the Congo basin. Sedimentary plains, developed mostly on weathered sandy materials, lie along the coastal stretches and cover vast areas of the Congo basin. Behind the coast the plain rises gradually to hills and plateaus of much lower elevation than those of the highlands of East Africa. Two great rivers, the Niger and the Congo, which discharge huge volumes of fresh water to the Atlantic Ocean, are major contributors to the hydrological cycles of the rain forests ecosystems of the Guinea–Congo Region. The Niger originates from the forested highlands of Guinea and discharges its waters into the Bight of Benin by way of a large delta in southern Nigeria. The Congo basin occupies an immense area of 750 000 km2, surrounded by Pre-Cambrian uplands. The alluvial floor of the saucer-shaped basin is flat, and marshes and swamps comprise a large proportion of the total area. The highlands and plateaus along the rim are low to the west and north and higher to the south. To the east, they merge with the mountains of the Great Rift Valley of East Africa (Gann & Duignan 1972; Hance 1975; Grove 1978; Hamilton 1989).

A front on the Great Plateau separates tidally mixed water of the North Channel from quieter less saline surface layers of the Outer Firth. These water bodies exchange about 1·6 × 104m3 s−1, leading to a residence time of two months in the Outer Firth surface layers. The position of the front is determined by the balance of mixing and buoyancy supply. The wind modulates weak tidal currents in the Outer Firth by driving surface currents and setting up deeper compensation flows. Deep water in the Arran Deep and Kilbrannan Sound is irregularly renewed by inflow of dense water over the Eastern Plateau from autumn to spring of about 1 × 104m3 s−1 but stagnates in summer below a thermocline. A minor part of this renewal comes over the Davaar sill into Kilbrannan Sound.

Bottom water of the fjordic sea-lochs is isolated in summer and renewed during the winter. The renewals occur by density currents flowing in from the sills and these produce a characterising grading of the bottom sediments from coarse to fine away from the sills.

The title to the talk this afternoon, “Abiogenic Information Coupling, or, How protein and DNA were married”, is, indeed, an excerpt from the much broader subject to which your President referred, namely chemical evolution of life on the surface of the earth, with some speculation about elsewhere as well. Actually, the “elsewhere” portion is more than a hopeful addition because it may provide a check on the speculations on the origin of life on the surface of the earth, which is very difficult to obtain inany other way.

A cytological analysis of a number of Sealyham, Spaniel, and Spaniel × Manchester Terrier dogs was undertaken in order to determine the number and structure of chromosomes during both mitosis and meiosis in each breed, and to ascertain the differences between them in respect of chromosome number and behaviour.

The major antioxidants present in the essential (volatile) oils of oregano (Origanum vulgare, L.), summer savory (Satureja hortensis, L.) and thyme (Thymus vulgaris, L.) have been identified as carvacrol and thymol which have both been demonstrated to possess fungicidal and bactericidal properties. EPR spectra produced upon oxidation are inconsistent with the expected phenoxy free radicals (RO), but resemble those of galvinoxyl and anthronyl radicals. The EPR spectrum, in the case of carvacrol, is a pair of quintets with isotropic splittings, 0.325 and 0.080 millitesla (mT). ENDOR and TRIPLE resonance experiments have been performed and are indicative of the paramagnetic species being a substituted anthronyl. Further studies are being conducted to characterise these species and to investigate their potential roles during oxidative stress.

The alkaloids of Ragwort (Senecio jacobæa Linn.) are known to be hepatotoxic to farm animals and man. Survivors invariably show permanent impairment of the liver, manifested by cirrhosis and its sequelæ. Senecio infusions may be consumed in small amounts in Britain as a herbal remedy, and in South Africa the Bantu frequently incorporate them in native medicines. It has been shown that these tribes have a high incidence of cirrhosis and primary liver cancer, and there is good evidence that their deficient diet may play an important part in sensitizing the liver to toxins. In the present study, the ragwort alkaloid seneciphylline has been administered by injection to fowls maintained on both adequate and deficient diets, and further fowls received the dried plant in their food. A significant proportion of these birds subsequently developed primary liver tumours. Although there was a higher mortality rate in both treated and controls fed the deficient diet, there was no evidence of a greater tendency to develop liver tumours compared with the birds on the balanced diet.

It is also suggested that the condition known as “cavernous angioma” of the liver of cattle and sheep in Britain may be due to ingestion of ragwort in sub-lethal amounts.

Since they first evolved, pteridophytes have been subjected to attack by micro-organisms and arthropods. Present-day ferns are associated with a complex array of, not only phytophagous, scavenging, predatory and parasitic arthropod species but also fungi, bacteria, viruses and herbivorous mammals.

Recent research has tended to stress the importance of secondary plant chemistry in deterring feeding by herbivores and attack by pathogens. Although ferns have a more limited chemical repertoire than the angiosperms, many of the classes of secondary compounds isolated from ferns have been shown to have anti-microbial and anti-herbivore activity under both laboratory and field conditions. Quantitative and qualitative levels are not constant and show great seasonal variation. This chemical variation is important in determining the seasonal patterning of insects and fungi on ferns. New chemical techniques are increasing our knowledge of the biosynthesis and chemical structures of these ecologically important compounds.

Flowering plants show both constitutive and induced resistance as a consequence of herbivore attack. A search for short-term induced chemical responses in ferns have so far yielded negative results in terms of phytoalexin synthesis or direct chemical response to herbivory.

Evidence now points to the existence of common patterns of functional specialisation in green plants and fungi. It is predicted that further research will reveal the basis for a universal functional classification of organisms which can be used to analyse the assembly rules of communities and ecosystems.

The Outer Hebrides comprise approximately 1·3% of the land area but 15·8% of the area of standing waters of Great Britain. Streams there are generally small and only three are as large as fifth order. The majority of the lochs occur below 200 m altitude and are less than 25 ha in area. A total of 1375 stream systems enter the sea, and drain the land mass through 9240 stream segments. There are just over 6000 lochs, of which less than half are connected to these networks. Most of the water systems are on geologically base-poor rock or soil, and less than 3%, situated on machair, are base-rich and eutrophic. The islands, due to their situation, receive precipitation in the form of very dilute sea water (with some non-marine sulphate probably derived from fossil fuel combustion) and this leads to unusual concentrations of chloride in the inland waters. Metamorphic rocks are resistant to weathering, so there is usually little variation in the composition of fresh waters except in the machair areas, where calcareous sands affect calcium concentrations and alkalinities.

The flora and fauna reflect the aqueous conditions and there are some unique successions of species from high to low salinities even in the same water body. The lochs provide a wide range of habitats for aquatic vegetation, ranging from the rich machair lochs to the oligotrophic peaty lochs (which show marked similarities with their counterparts on the mainland). Three broad categories can be delineated on the basis of their water quality and vegetation: brackish lochs with varying degrees of marine influence, calcareous machair lochs which may also be affected by sea connections, and the peaty lochans of low alkalinity. A few brackish water animals are sufficiently euryhaline to exist in the machair lochs, which are otherwise dominated by freshwater species. The occurrence of chloride in inland waters enables some crustaceans, e.g. Neomysis integer, Gammarus duebeni and Diaptomus wierzejskii to extend into what are poor freshwater habitats. The main constituents of the freshwater fauna are molluscs and arthropods, and a few species of euryhaline fishes, i.e. salmon, sea and brown trout, three-spined and ten-spined sticklebacks and eels. There are some populations of non-migratory charr. No amphibians are present.

Autecology of pteridophytes may be refined by defining the plant community and habitat, and phytogeographic occurrence, of the species studied. Work with Blechnum spicant in the Pacific Northwest, and with Lorinserea areolata in the Southeastern U.S.A. has uncovered autecological differences for these species across habitats differing in overstory and hydrology. Natural history observations are necessary to suggest the most appropriate hypotheses to investigate objectively. A modification of Daubenmire's Canopy-Coverage method provides a grid across which many factors may be recorded or tested in repeatable objective manner. Such an analysis was used to test the association between L. areolata life-history classes and hummocks in hardwood swamps. Contingency tables were used to disprove the null hypothesis that L. areolata was distributed randomly with regard to hummocks. Hummocks were thus ‘safe sites’ for the completion of the life-cycle of L. areolata, and additional considerations of safe sites for Lygodium japonicum and Dryopteris ludoviciana are introduced. Analysis of biomass and coverage of Onoclea sensibilis where it is very abundant suggests that it is highly susceptible to competition where it shares plots with L. areolata. The concept of the optimum habitat with regard to abundance of the taxon, frequency of the habitat-type, successful reproduction, and susceptibility to competition between similar life forms is discussed.

Plants of Boea hygroscopica were grown in a controlled environment. Control leaves were detached from plants grown in well-watered conditions and then subjected for 144 h to rapid or slow dehydration. Dehydrated leaves were then rehydrated for 36 h in distilled water. Rapid-dried leaves were not able to revive, whereas slow-dried leaves recovered their normal metabolic status. Results showed a different superoxide radical production in the dehydrated leaves accompanied by an altered lipid composition. Rehydrated leaves recovered the original lipid composition of control leaves. Spin-labelled thylakoid proteins of dehydrated leaves showed lower -SH group levels and increased spin motion.

In Dutch coastal dunes, geomorphological and geohydrological processes have been adversely affected by intensive utilisation of the dunes. In the past, wide-scale stabilisation, notably for reasons of coastal defence, stopped nearly all aeolian activity. Rejuvenation did not take place and succession to mature-type ecosystems increased. Artificial infiltration with eutrophic river water and extraction of groundwater for drinking water catchment modified the geohydrology of the wet-dune environment.

Today, actions are being taken to restore geomorphological and geohydrological processes. Managing authorities join forces with universities and policy makers to strike the right balance between conflicting interests. Applied research helps to develop management strategies.

Two types of research are discussed: (a) geomorphological work on the development of blow-outs; (b) geohydrological work on the development of dune slacks. Questions considered are: do blow-outs grow to an unlimited extent or do they have optimum size and shape corresponding to aerodynamic conditions? Are there natural stabilisation mechanisms for blow-outs? What is the ecological impact of drinking water catchment? Which aspects should be considered to restore the dune slack environment in catchment areas?

Our findings are that blow-outs in The Netherlands have an optimum length:width ratio of about 2 with a blow-out length varying between 20 and 30 m. After 10–15 years without artificial stabilisation measures, the areas studied present an average of about one blow-out per hectare. Natural stabilisation mechanisms include algae which colonise deflation sites inside the blow-out and low secondary dunes which develop at the immediate leeward side of the blow-out. Blow-outs situated at or near downhill slopes of 6–12° may easily extend into larger deflation surfaces. Water erosion, probably caused by the water-repellency of humus-rich top soil, often precedes wind erosion on south- and south-east oriented slopes.

Drinking water production caused dessiccation of dune slacks and the disappearance of associated vegetation. In areas where infiltration with river water from outside the dunes is also applied, inudation and eutrophication drastically changed the dune environment. Nitrophilous plants appeared, especialy along banks of infiltration ponds, but also in seepage ponds. The plant cover depends on nutrient concentration of the (infiltrated) groundwater but especially on the flux of the groundwater. A high rate of flux leads to high nutrient loads, encouraging the growth and eventually dominance of nitrophilous plants. Restoration of dune slacks depends on the quality and the flux of the groundwater, on the streamlines of the groundwater flow in the dune body in relation to the orientation of the seepage ponds, on the presence of peaty or clayey adsorptive layers in the subsoil and possibly also on the presence of a rainwater lens occurring on top of the infiltration water.

Various species of the lamellibranch Gryphœa have received much attention from palæontologists in the past twenty years, partly because careful collecting appears to have produced continuous series of forms (lineages) and partly owing to the problems which are raised by their progressive development from more normal oysters.

Macrobenthic bioturbation and microbial activity can have major ecological effects on present day marine sediments some of which are also seen in the fossil record. The coastal and estuarine sediments in the Clyde Estuary area are described. They contain very high densities of benthic macroorganisms and microorganisms. These organisms have dramatic effects on the physical and chemical properties of sediments, and field and laboratory studies have shown that many geotechnical and geochemical properties of sediments are dictated by them. The effects can be on a microscale of a few millimetres horizontally or vertically (micro-spatial variation), or can have large scale consequences over hundreds of metres (macro-spatial variation).

Sediment stability (shear strength and critical erosion velocity), permeability and particle sedimentation are all altered by macro-invertebrate bioturbation or microbial activity, and many chemical properties such as Eh and pH may be influenced in a similar manner.

Biological activity may therefore play a major role in modifying sediment geotechnics and early sediment diagenesis. It also has direct relevance to the siting of man-made structures on the sea-bed and to sediment stability and transport in estuaries. In situ seeding experiments may lead to biological control and manipulation of these most important field phenomena.

The Turkish forests are a complex of Mediterranean, European, Euxine and Irano-Turanian influences. The boundaries between these 4 bioclimatic-biogeographical zones have, especially in the E of the country, been little studied and their limits are difficult to establish. Phytosociological and biogeographical aspects of these forest zones are discussed. In the bioclimatic-Mediterranean region, the forest and pre-forest structures are related to QUERCETALIA ILICIS in the thermo- and meso-Mediterranean stages, and to QUERCETALIA PUBESCENTIS in the supra-Mediterranean stage, except in southern Anatolia where they belong to QUERCO-CEDRETALIA LIBANI. In the prepontic bioclimatic region where the Mediterranean influence is still perceptible, they belong to QUERCO-CARPINETALIA ORIENTALIS and in the Euxine bioclimatic region to RHODODENDRO-FAGETALIA ORIENTALI and to PINOPICEETALIA ORIENTALIS. Some forest formations in NW Anatolia, with a European mountain influence, are related to FAGETALIA SYLVATICAE and to VACCINIO PICEETALIA.