Search

Presents a correction to the article "The Influence of the Severe Winters of 1939-42 on the Soil Fauna of Tipperne" that was published in a previous issue of the journal "Oikos."

The article presents a research paper that discusses a growth experiment with egg larvae of Hylotrupes. The experiment was conducted in filter paper designed as a 5 x 5 hyper-Graeco-Latin square with different categories according to treatment contrasts. Random sampling was performed by random consecutive numbering and its estimates were obtained from a variation between similarly treated larvae. The analysis of mortality within the groups proved that the growth is affected by the doses of peptone and cholesterol.

The present paper deals with caloric values of important plants and insects occurring m the grassland vegetation at Kurukshetra, India. The data indicate variations in energy content among different species and at different seasons. [ABSTRACT FROM AUTHOR]

This paper reports on seasonal cycles of physical and chemical factors, over a period of two years, which were expected to affect the size and seasonal variation of phytoplankton production in the eutrophic, dimictic Lake Esrom, Denmark. Insolation, transparency, temperature, oxygen, total carbon dioxide, free carbon dioxide, pH, alkalinity, silicate, nitrate, ammonia, orthophosphate and total phosphate, were measured to describe the lake hydrography. They are presented as isopleths. After the spring maximum of phytoplankton, nitrogen and silica rapidly declined to insignificant and limiting concentrations while phosphate- phosphorus declined to 50% (150 μg litre-1) of the winter value. Light can limit phytoplankton production at all seasons. A phosphorus balance showed that there was about 80 t of phosphorus in the lake. Phoshorus recycled in the lake ecosystem was 20 t, 10 t from tributaries and 10 t annually being added to the sediment. The evidence for enrichment includes a discussion on the history of the lake, coring, ground water analyses, changes in hypolimnetic dissolved oxygen, and changes in transparency. The possible influence of pollution from sewage is discussed in relation to the estimated nutrient budget of nitrogen and phosphorus. Increase in nutrients failed to increase phytoplankton production during 17 years. [ABSTRACT FROM AUTHOR]

The pollen content of the organic layers of nine soil profiles in the Forest of Abernethy, Inverness-shire was examined. From a discussion of the process of raw humus formation, it would appear that Mor is a broadly stratified deposit in which favourable conditions exist for the preservation of pollen, although a number of factors which may lead to the deterioration of pollen, or disturbance of stratification are also considered. Pollen diagrams from Mor profiles were interpreted with the aid of surface sample data from Abernethy presented in an earlier paper, 14C-dating of soil material, and documentary evidence. It is concluded that substantial areas of Calluna-dominated heathland have existed in Abernethy since at least AD 400, and that prior to heathland formation, some parts of Abernethy may have contained vegetation consistent with the presence of Mull rather than Mot. [ABSTRACT FROM AUTHOR]

The present paper is the first part of number two (B) in a planned series of four, all dealing with the annual rhythm of production of gramineous plants. This paper reports a two years experiment in photothermostats. The experiment was carried out in thermostats with electric light. The heat from the lamps was reduced through mantles of circulating water. The temperature varied around a mean of 17°C. The electric light was on during 16 hours a day and the rest of the day it was dark. The humidity varied around 61 %. The content of CO2 in the air was continuously determined. The plants were sown every fourteen days in brick pots, standing on deep plates of glass. They were harvested along with the roots after four weeks of growth. The capacity of germination of the seed was tested before every seeding in the first three quarters of the experiment time (Table I). The different seedbeds and experimental plants are listed on page 142. Some series received nutrient solution, others not. The nutrient solution is described on page 145. It was given in water solution after the seedings, and fourteen days later on the plates. Watering with distilled water was given on the plates every third thy. The data are graphically represented in Figs. l-6, as described in the text. All growth curves are typically unimodal. They have summer and autumn minima and winter and spring maxima. These variations are the same in both experimental years. Only the amplitude increases on addition of nutrient solution. For the first category of curves by as much as 300 % of the lowest figures. All curves for roots, with and without nutrient solution, had about the same amplitude. The curves for tops, without nutrient solution, had about the same amplitude as the curves for roots in all experimental series (Figs. 1-6). As a consequence, the root weight in per cent of tops was very high in the series without nutrient solution - 112 % - (Table 3), and in all curves it was the highest during periods, which had a low production. The present paper is mainly presenting the data, and further discussion is postponed until the data for another two year experiment in thermostats are presented. In that other experiment, analyses are made both on the soil before each seeding and of the tops of the plants after each harvest. Literature will be given in a later paper. [ABSTRACT FROM AUTHOR]

The present paper is the second part of the first one in a planned series of four. It reports one series of experiments and compares the results with those of one experiment reported in the first paper of the series (RAPPE 1963). The experiments were carried out on field plots with an abundance of water and most nutrients, but without nitrogenous nutrients. It included eleven species of perennial grasses in pure stand, and the same eleven species in mixed stand with white clover. The plots were cut every three weeks, on dates to be seen in the figures and tables, giving ten cuts every season of growth. The experiment lasted for six years. The data are graphically represented in Figures 1-4 and listed in Tables 1-4, according to principles described in the text. All diagrams of the growth of native grasses in pure stand, nine species, are markedly bimodal with a minimum around the midsummer, whereas those for non-native grasses, two species, are unimodal. Most diagrams of the mixed stands of grasses with white clover, eight species, six native and two non-native, are unimodal and the rest, three species, are bimodal. All eleven diagrams for the clover part of the mixed stands are unimodal, as well as five of the eleven diagrams for the grass parts. three native and two non-native. The remaining six are bimodal. Explanations are attempted of the problem of clearly two-topped growth curves in these experiments on field plots, in comparison with the grass curves in the experiments in pots, already published (RAPPE 1963), where there was a small peak between two large ones. As for the distribution of grass production on the seasons, the tendency towards a large part of the yearly production in late summer and autumn varies rather considerably. Thus some species have nearly half of their production after the end of July, whereas others have less than a third of it during this time, the other species showing intermediate proportions. The means of all eleven grass species in pure stand, as well as of the grass parts of the mixed stands, are both bimodal. Thus the white clover in mixture with the grass species shows a clear tendency to even out the normally markedly bimodal growth of the native grasses in the direction of unimodality. The white clover part of the mixtures always has a clear unimodal growth. [ABSTRACT FROM AUTHOR]

1. The present paper deals with the effects of river regulations on the fauna living in the rapid regions of the River Stora Lule Älv, which is influenced by the Suorva Reservoir since 1927. The conditions in the natural river system of the river Lilla Lule Älv are compared. 2. The changed rhythm in which the water runs off caused by the regulation is explained by several examples of natural rivers. 3. As opposed to the unregulated river Lilla Lule Älv the river Stora Lule Älv shows anormal glaciation whith radical influences on the topography of the river bottom and its flora and fauna. 4. The damming up of snow and glacier melting waters cause essential divergences from the natural development of temperature in regulated rivers, disturbing the vital function of the organisms. 5. Investigations on the way in which the waters run off dammed and natural lakes show, taking into consideration the »Organic Drift« and the bottom fauna, the negative consequences of the regulation on the rapid regions below power dams. 6. An experiment at the power dam of Selsforsen showed that by taking plankton rich surface water also below power dams a rich bottom fauna can live in the river. [ABSTRACT FROM AUTHOR]

The present paper is the first one in a planned series of four, all dealing with the annual rhythm of production of gramineous plants. The present paper reports two experiments. One of these was carried out in concrete pots with an abundance of nutrients and water. It included nine species of perennial grasses and four experimental years. Once a week during the growing season a set of pots was cut, each pot being cut every second or every fourth week. In this way weekly data were obtained concerning the production during the previous weeks. [ABSTRACT FROM AUTHOR]

1. Wild house mice have been bred at 18°C, 25°C, (partly at 70% R.H. and partly at 85% R.H.), and 32°C. From their birth to the age of 90 days the mice were regularly weighed, and from the age of 15 days the length of body and tail was measured. The age for attainment of fecundity was recorded. 2. Among the nestlings, the mice at 32° are a little heavier than at the other two temperatures — later on the mice at 18° are significantly heavier and have significantly longer bodies than at the other two temperatures. Already at the age of 15 days, viz., before the thermoregulation becomes functional, the tails area significantly longer at 32° than at 18°. At the age of 60 to 90 days the tails at 32° are about 45% longer than at 18°. That a lengthening of the tail may be caused by other factors than a higher temperature, is indicated by the fact that of the mice grown up at 25° those kept at 85% R.H. have significantly longer tails than those kept at 70% R.H. The lengthening of the tails is due to a lengthening of the individual vertebra, the number remaining the same. No difference in age for attainment of fecundity or in fertility was demonstrable. Nor was it possible to show a significant difference in litter size at the three temperatures. [ABSTRACT FROM AUTHOR]

The present paper deals with the species of Oribatei living in a number of northern biotopes. The total number of species found is 127, some of which are new or little known. Most of them are eurytopic but some seem to be strictly bound to one or a few types of environment. In several cases also the eurytopic mites have a tendency to prefer a certain biotope which means that they tend to be strangers in most others. This tendency will be discussed in a following paper. [ABSTRACT FROM AUTHOR]

This paper is the second in a series of investigations on the factors influencing the leaching of different species of litter. The first paper dealt with the leaf litter of Fraxinus excelsior. The present paper is a report of corresponding experiments on needle litter of Pinus silvestris. The study found that the amount of water-soluble organic substances obtained in one day of anaerobic leaching of pine litter is less than 1 percent of the dry weight of the litter. The amount increases during the whole time of leaching. After 43 days, it was about 3 percent of the dry weight of the litter.

The article presents a paper focusing on the study of agriculture in Denmark. Denmark has a windy climate. The yearly precipitation is about 725 mm in the South-West of Jutland and about 550 mm on the island Zealand where Copenhagen is situated at the East shore. The actual evaporation increases from about 350 mm on sandy soils in Jutland to about 450 mm on the South-eastern Danish islands with soils having a relatively high capacity for water available to plants. The highest actual evaporation coincides to some extent with the lowest precipitation. In this paper evaporation also covers the term evapotranspiration. The potential evaporation is considered to be near 500 mm for most parts of the country. In May-July the potential evaporation is much larger than the precipitation. Shelter is considered important in Danish agriculture to avoid wind erosion on sandy soils and to reduce water evaporation. The increased temperature by shelter is generally assumed to be more important in horticulture than in agriculture. It is well known that shelter increases plant production.

The paper describes a method for testing the ability of wood boring larvae to distinguish different sorts of food. Thin slices of sapwood of pine and filter paper were used, both impregnated with peptone in successive concentrations and with or without the addition of aqueous yeast extract. The various preparations were examined for their relative nutritional value to larvae of the House Longhorn beetle, Hylotrupes bajalus L., and used in different combinations in preference experiments with these larvae. The relative nutritional value showed a clear dependence on the concentration of peptone and a very pronounced positive effect of the yeast extract in wood, while this effect was much less significant in paper, especially in the highest concentrations. This is supposed to be due to the lack of other vitamins in paper. The experiment discloses a clear preference for the highest concentrations of peptone except in wood without yeast. On a later observation this exception was found to be due to the fact that, being small enough to confine themselves to a single piece of veneer, the larvae in this group are disinclined to leave the pieces to avoid penetrating the surface. The experiment does not furnish any proof that the reaction of the larvae is due to the nutritional value of the food rather than to the proper concentration of peptone, but it indicates this possibility. It is pointed out that the growing larva avoids penetrating the surface of the wood, although it is normally the larva which bores the exit hole before it pupates. [ABSTRACT FROM AUTHOR]

The author has studied Ophrys insectifera L. (Orchidaceae) in respect of floral biology during several years in South Sweden (province Öland), North Sweden (province Jämtland), and Norway, Field observations as well as experiments have been performed. In Algeria, Morocco, and Lebanon other species of Ophrys are being studied by the author. Many insect species and several spiders are recorded as visitors — accidental or regular — on the flower of O. inisectifera. In Sweden the author hitherto has observed two Sphecids (only males), Gorytes mystaceus L. and Q. campestris L. (= fargei Sm.), and one Staphylinid, Anthobium minutvm F., as the only regular and effective pollinators. The Gorytes males are attracted by the scent of the flower which is stated by the author being similar to one of the female of mystaceus. The outline or contour does not attract, but the dark purple colour of the labellum has in a near distance some attractiveness. Anthobium is pollenfeeding. The scent of the flower stands between that of farnesol and hydroxyeitronellal. I have stated that odours resembling those of farnesol, eitronellol, eitronellal etc. are rather common among Apids, Sphecids and Ichneumonids. In many flower perfums these constituents are to be found. The Gorytes males are strongly attracted and excited by the scent of the flower and behave on the labellum in a similar way as during the introduction to copula depending on tactile stimulation from the stability, contour and hairy coat of the upper surface of the labellum. During the tactilely guided movements the pollination is brought about. Anthobium is not tactilely stimulated in this way. There are resemblances between the superficial structures of the upper side of the labellum and that of Gorytes. The author considers whether the biological dependence of the O. insectifera to the Gorytes males in respect of the fecundation is to be regarded as an adaptation or not. It seems that the plant utilizes the somewhat "imperfect" releasing mechanism of the copulatory activity of the Gorytes males. The occurrance of pollinators of the "Anthobium-type" must not be depreciated even though it is possible that O. insectifera originates from a milieu populated by insects of the same or similar ethological constitution as the two Gorytes species — or perhaps by just the same Gorytes species. Perhaps Anthobium minutum or a related type has played a rather important role for the distribution of O. insectifera in regions with cold climate. I have not been able to state spontaneous autogamy as it is discussed by ZIEGENSPECK and WOLFF. It seems to me, as the bending down of the pollinia or the falling out of them on the labellum described by these authors, ought to be regarded as vestiges from visits of Anthobium, Nitidulids or perhaps yet other pollenfeeders of related behaviour. This paper is a preliminary report. In the papers 1950 the pollinator of O. lutea is with some hesitation named Andrena propinqua. Prof. Pittioni of Vienna has recently determined the specimens sent to him as belonging to A. freya Strand. [ABSTRACT FROM AUTHOR]

This paper reports a time-varying coefficient, linear, compartment model of herbage dynamics for tropical grasslands in India. The model has been used to depict intra-seasonal changes in various primary producer compartments in three grasslands by adjusting some of the transfer coefficients. [ABSTRACT FROM AUTHOR]

Insects were sampled from March 1968 until September 1969 in the forest savanna mosaic belt of the Ivory Coast, This paper deals more specifically with the species occurring in the boundary between the gallery forest and the savanna. Two sampling techniques were used simultaneously: Moerike's yellow water traps and square metre quadrat cages. 38 species of Jassidae were found of which five constituted 85% of the total numbers. During the rainy period the insects were highly active in their respective habitats, Movements between the forest and savanna were, however, uncommon. During the dry season the insects were largely inactive, and were taken mainly in the quadrat cages. Some migration between the two biotopes took place at this season. [ABSTRACT FROM AUTHOR]

Environmental systems analysis, or systems ecology, deals with the mathematical modeling of environmental systems as sets of coupled compartments with time dependent changes in amounts of elements, compounds and energy described by mathematical equations. A basic premise is that environmental systems may be simulated with mathematical equations utilizing the same assumptions about underlying properties that permit the use of similar equations in engineering. Systems analysis techniques are used in many fields of science and engineering where the dynamic response of a system is of interest. Ecologists have long recognized that nutrient elements cycle and energy flows in the environment from one trophic level to another, but only recently have they learned to apply the well-developed mathematical techniques of systems engineering to ecological problems. This paper discusses feasibility and techniques, with examples of applications of systems analysis to the modeling of a forested ecosystem, emphasizing the role of earthworms in organic matter decomposition and the contribution of this process to carbon flow in the ecosystem. [ABSTRACT FROM AUTHOR]

Mercury pollution of soils and streams is primarily a local problem, requiring careful monitoring and regulation of effluents. Mercury is translocated to the sea only slowly from soil and stream, but rapidly by precipitation from the air. Mercury levels in marine fish may rise above acceptable levels if the combustion of fossil fuels with a high (≅ 1 ppm) mercury content continues. In the ocean and marine biota, mercury can persist for several decades after pollution stops. Control of mercury pollution must anticipate levels up to sixty years in the future in order to be effective. Further experimental research is needed to obtain data on the mercury content of fossil fuels, on possible natural mechanisms for the release of mercury into the air, and on conversion mechanisms for methylation of mercury in the soil, ocean, and fish sectors. [ABSTRACT FROM AUTHOR]

For the 29 most common litter and soil nematodes in Hestehave beech forest the following information, derived from 12 monthly samples, is given: mean number and live weight per m² with percentage juveniles, females, gravid females and males; percentage distribution in litter, 0–3 cm soil, 3–6 cm soft; number identified per month; mean individual biomass; total increments per m² in numbers and biomass; annual oxygen consumption; calorific equivalents of annual biomass increments and oxygen consumption. Annual mean total nematodes per m², corrected for extraction efficiency, is 1,432,000 with a biomass of 370,000 μg m-2 and a total energy flow of 14,000 cal m-2 year-1. Calorific equivalent of biomass production is 3230 calm-s and of respiration 10,800 cal m-2, with total respiration 2,270 ml O2 m-2 year-1. Annual production is 20.7 per cent of total energy flow and energy flow 28.5 kcal g-1; these are discussed in relation to previous estimates for nematodes and other soil invertebrates. [ABSTRACT FROM AUTHOR]

Pollen deposition in each of five categories of vegetation in the Forest of Abernethy was examined by collecting surface samples. Qualitative differences in the composition of pollen spectra from category to category were revealed enabling simple distinctions between vegetation categories to be made. Comparison between categories was then placed on a semi-quantitative basis by compiling modal percentage frequencies for each main pollen type recorded in each category, and this data was used to construct surface pollen assemblages characteristic of each vegetation category. The application of these surface pollen assemblages to the paleoecological problems of Scots Pine forest will be considered in detail in a subsequent paper. [ABSTRACT FROM AUTHOR]

Drop-covered surfaces in the landscape such as dew covers cause increased reflection of the incident light in a direction towards the light source, so-called retroreflection. Surveyable registration in the form of imagery of retroreflected light from pound surface and vegetation, for instance from an airplane, may provide valuable climatological and biological information. Different factors influencing the retroreflection are treated in the paper. Among these the lens-effect of the drops is dealt with in detail, and goniophotometric experiments with laser light are mentioned. An active remoteasensing system for registration of retroreflected light from drop-covered surfaces is described. The system Consists of a laser scanner equipped with an image-producing device. Laboratory tests with the apparatus are presented as well as planned activities with the equipment. [ABSTRACT FROM AUTHOR]

A method is described by which the rate of degradation of different kinds of cellulose fibers was determined in aquatic environments. The fiber samples were enclosed in small bags of nylon fabric with a fine mesh and weight losses of bags placed in water or sediments were measured over periods of several months. Newly processed pulp fibers were rapidly degraded in aerobic, nutrient-rich water whereas previously dried pulp and fibers derived from cotton were degraded more slowly. Lignin-containing mechanical pulp was hardly degraded at all. Cellulose decomposition was slow in unpolluted sea water and in the heavily polluted, anaerobic water outside a paper mill but relatively rapid both in the anaerobic water and the sediment of a nutrient-rich lake. The applications and limitations of the bag method in studies of decomposition processes in aquatic ecosystems are discussed. [ABSTRACT FROM AUTHOR]

1. Energy flow and accumulation in the above pound parts of an alder-birch woodland in County Durham were studied between April 1966 and April 1968. This paper reports data for the tree stratum of the Wynyard woodland. 2. Tree net above ground primary production was 3574 Kcal/m2/year. 2417 Kcal/m2/year (68.0%) was wood. 901 Kcal/m2/year (25.0%) canopy leaves, 232 Kcal/m2/year (6.47,) other parts, and 24 Kcal/m2/year (0.6 %) loss to herbivores. 3. Tree litter fall was approximately 1450 Kcal/m2/year in both study years. 66.0% was alder and birch leaves, 19.2% small wood, and 14.370 other litter. Seasonal changes in canopy biomass, biocontent and Leaf Area index were demonstrated. 4, Total biocontent of tree boles and branches in the 1967-8 winter was 50,912 Kcal/m2/year (10,679.2 g/m2). 3. Tree litter fall biocontent was close to 40.6 % of tree above ground net primary production in both study years, and its ratio to biocontent in the 1967-8 winter was 0.028. [ABSTRACT FROM AUTHOR]

The hydrology and salinity properties of Baltic sea-shore meadows in an area about 60-150 km south of Stockholm have been related to the main plant communities described in previous papers. Fluctuations in the water level of the sea and the water level of open pits have been recorded and the measurements compared with the zonal differentiation of the plant cover. The seasonal variation in the salinity of the rhizosphere is illustrated and discussed. It is concluded that high salinity exerts a powerful selection and only a few specks will be able to survive. Within the vegetation complex, however, drainage conditions chiefly decide the vertical range of the enduring species and the zonal differentiation of the plant cover. [ABSTRACT FROM AUTHOR]

The purpose of this investigation, carried out during May-June in 1966-1968, was to shed some light on the qualitative changes in the breeding bird fauna that result from an alteration of land use along lakes, watercourses and coasts in southern Sweden. Special attention was paid to the Black-tailed Godwit (Limosa limosa), the Redshank (Tringa totanus), the Dunlin (Calidris alpina schinzli) and the Yellow Wagtail (Motacilla f. flava). The type of land use considered is that of cattle pasturage, which is being widely discontinued in the areas studied. Therefore the study areas were chosen to represent a series of different grazing intensities and stages of revegetation. Moreover, the land use factor was isolated from other factors affecting the vegetation. The study showed that few species were common to both grazed and ungrazed areas. The bird fauna was generally more varied in an un-grazed area than in a corresponding grazed one. Only if the ground, after it was abandoned became covered with Phragmites communis (Trin.) was the former avifauna replaced by a less varied one. The paper also discusses some bird species, which during the last hundred years have been affected - positively or negatively - by changes in land use within areas close to the shore. [ABSTRACT FROM AUTHOR]

Quantitative and qualitative analyses of phytoplankton in Lake Assjön, southern Sweden, were carried out during the period May 1961 to July 1962, incl. Some physical and chemical data from the period are given. The list of species includes ca. 100 taxa dominated by the group Chrysophyceae. The total volume of phytoplankton was low throughout the period: only once a value of 400 ∙ 106μ3/1 was exceeded. This was obtained in July when Dinobryon spp. and small flagellates predominated. In the spring of 1961 relatively high volumes of diatoms were recorded. As to total volumes some comparisons were made with corresponding values from Lake Vättern and from some lakes within the drainage area of Lake Mälaren. The phytoplankton of Lake Assjön is also compared with that of Lake Södra Vixen which has about the same trophic level. Comparisons were also made with data from six other lakes situated close to Lake Assjön: all these lakes were investigated in May 1961. The total phytoplankton volume in lakes of the type described in this paper exceeds a value of 1,000 ∙ 106μ3/1 (1 mm3/1); as a rule values lower than 500 ∙ 106μ3/1 are obtained. [ABSTRACT FROM AUTHOR]

The distribution of littoral Enchytraeidae was determined on an Anglesey beach by means of baited bags. L. reynoldsoni was found chiefly above the Pelvetla zone, white L. lineatus was more widely distributed. The salinity preferenda of these two species were determined by means of multiple-choice chambers, in which different salinity regimes were maintained on moist blotting paper balls. L. reynoldsoni was found to prefer salinities less than half that of the sea-water, while L. lineatus displayed no preference over a range from distilled water to a salinity 1.5 x that of the sea-water. Both species showed marked tolerance for sea-water. L. reynoldsoni was apparently unable to prevent water loss when transferred from a weaker to a stronger strength of sea-water. Fluids collected from the upper shore on absorbent cotton pads were found to have generally low osmotic pressures, depending upon rainfall. L. reynoldsoni was found to be attracted to both fresh and decayed sea-weed, It is concluded that the distribution of this species is governed by low salinities and the presence of a drift-line of sea-weed. [ABSTRACT FROM AUTHOR]

Corynephorus canescens presents two distributional problems in Great Britain; first, as a species with restricted distribution, and second, as one at the northern edge of its distribution. The first problem may be related to the past history of any one dune system and in particular the continuance in time and space of open sandy habitats of intermediate stability; the possible factors limiting Corynephorus at the northern edge of its distribution are considered in the body of the paper. The maintenance of Corynephorus populations is dependent on successful production and dispersal of' seed, germination and seedling establishment, Reproductive capacity and seed viability arc high. No dormancy mechanisms have been detected. Seed after-ripening is little affected by low temperature (0°C) and the seed is fully ripe eight weeks after anthesis. Germination is slowed down at temperatures below 15°C. Germination in the field Is controlled by the availability of moisture for imbibition and its rate by temperature. The later the emergence date of seedlings ía the field, the lower the chances of seedling survival. Seedling mortality occurs at a number of stages. It is concluded that the climate beyond the most northerly locality of Corynephorus in Great Britain (57°45' N) is severe enough to have a cumulative effect on flowering date and seed germination sufficient to postpone emergence date of the seedlings bcyond the critical time for their survival. [ABSTRACT FROM AUTHOR]

An instrument is described which employs a mercury current-integrator ("Curtis Meter") in series with a thermistor and a mercury battery. This can be used to integrate temperatures at very precisely known localities even in thermally stratified habitats such as soil. The device has an overall accuracy of at least ±0.25°C and can be read in the field without the need of delicate measuring equipment. In the paper a convenient method of calibration is described and some practical results are given to illustrate the effects of vegetation and of aspect as seasonal cycles of soil temperature. [ABSTRACT FROM AUTHOR]

This paper concerns the efficiency of the logarithmic transformation when applied to Oribatei censuses. From our observations, it appears that the transformation is usually able to normalize approximately the sampling frequency distribution (criteria g1 and g2). However, although the transformation considerably reduces heterogeneity of variances for a given species, it does not homogenize them sufficiently in cases where density variation is very great. [ABSTRACT FROM AUTHOR]

1. This paper concerns the populations of 13 species of soil Oribatei in two forest communities, studied by the analysis of frequency distributions of individuals in the samples. The data are based on a total of 1200 samples collected in the course of one year. 2. A statistic G1 is used to discriminate between the different theoretical distributions which have been proposed to allow for overdispersion, viz. Neyman type A, Polya-Acppli, negative binomial and discrete log-normal. It is shown that, in general, the negative binomial is the type of distribution which most frequently occurs in our fauna. 3. The application of the U and T test to each species at the different times of the year confirms this conclusion. 4. Among different biological models which might generate a negative binomial distribution, it appears that, for our fauna, the most likely is the heterogeneous Poisson model, according to which the distribution is considered to be the summation of a set of Poisson series in which the means arc distributed according to a Pearson type III distribution. In this case, the parameter k of the negative binomial can be considered as a characteristic of the heterogeneity of the distribution of a species in his habitat. 5. For a given species, it appears that, when the density falls, the heterogeneity of the distribution generally increases, the animals probably being clumped in the most favourable sites and being, at this moment, indifferent to intraspecific competition. In spite of differences in density, it is possible, however, to detect patterns which are characteristic of the different species studied. [ABSTRACT FROM AUTHOR]

This paper reports current research concerning Oribatid populations occurring in three ecosystems (an oak forest, a meadow and a poplar plantation). The main criterion used in the faunistic analysis is the relative density; this is expressed as a percentage and conventionally represented by ten classes (Fig. 1). The specific components of each habitat are compared at first wholly (Fig. 2) and then on the more rational basis or the Oribatid mites group peculiar to each milieu or in common with all the habitats (Tab. 1). The study of the relative density sums indicates the interspecifics quantitative connections, but also the similarities and the divergences between the three habitats (Tab. 2, Fig. 3). In the same way, the relationships between the three communities are established on the basis of the species list; those results show not only the connecting species but also the discriminating species (Fig. 4). The conclusions obtained are validated by considering various concepts such as the diversity, the constraint index and the specificity. [ABSTRACT FROM AUTHOR]

The genus Dysdera comprises approximately eighty species, of which the great majority are Western European or Mediterranean in distribution, This paper is one of a series resulting from an investigation into some of the basic problems of Dysdera taxonomy (see Cooke 1965a for a general account) and summarises our present knowledge of the biology of the group. The main topics discussed are the prey, predators and parasites of Dysdera, and various aspects of the sexual biology. Under the latter heading are included sections on courtship, copulation, seasonal activity and egg laying. An account is also given of interspecific matings, which although never occurring in wild populations, may occasionally be induced in laboratory-reared individuals. The eggs resulting from such mating are infertile. [ABSTRACT FROM AUTHOR]

1. The paper deals with Lipoptena cervi (L. c.). The material is from Jægerseborg Deer Park, Zealand, and consists of 1 ♀ L. c. from fallow deer, and 86 ♀♀ and 94 ♂&3x2642; from red deer, all collected from Sept.-Dec. 1960. 2. Morphology of the mouthparts makes L. c. a pool feeder (plates 1-II, Fig. 2). The claws (Fig. 3) are adapted for woollen hairs or contour hairs with diameters less than 0.22 mm. L. c. is moving sideways through the coat with head downward and almost perpendicularly to the skin. The wings are torn off by the hairs in the coat. 3. In Denmark L. c. is univoltine with appearance of a new generation in Sept.-Oct. when the red deer changes from summer to winter coat. Each healthy red deer is considered to have a carrying capacity of about 15 specimens of L. c. 4. The difference between frequency of infestation by L. c. on fallow deer and red deer is explained ecologically as a result of better chances of survival for puparium and winged stages in the habitats of red deer (woodland) than in those of fallow deer (grassland). 5. Unwinged stages show an aggregated distribution on their hosts (Fig. 5). 6. The background for aggregation is discussed with special reference to possibilities of persecution by the host, to skin temperatures (Fig. 5), and to the microstructure of the skin (plates III-VIII, Figs. 7-11). Supplementary temperature measurements on skin and in coat were made on fallow deer (Fig. 4), and cow (Fig. 6). The aggregated distribution is explained as the result of a balance between several factors (results on pp. 126-127). [ABSTRACT FROM AUTHOR]

The present paper shows the variations of ionic composition of waters chemistry in Central Sweden. Within one area, Uppland, the influence of geochemical conditions through high proportions of calcium and bicarbonate in lake water largely depends on the abundance of calcareous marl. Going about 100 km northwards, magnesium among the cations and bicarbonate and sulphate among the anions become dominating, due to larger influence of airborne salts than leached salts. Going westwards from Uppland, bicarbonate and sulphate dominate as when going northwards. Among the cations calcium dominates as in Uppland but to a lesser degree. Exceptions from that are lake waters located in a Cambro-Silurian moraine, where the ionic composition of lake water approximates that of Uppland. [ABSTRACT FROM AUTHOR]

1. Some objections to the usual way of expressing the total amounts of salt in the littoral subsoil water as S% are made and measurement of the electrical conductivity is recommended. 2. It is pointed out that the conception of euryhalinity does not exclude a preference for a certain part of the salinity scale which is the theme of this paper. 3. A new alternative chamber for salinity is described. 4. The resistance of Akiedrilus monospermazecus from 6 S% and Marionina preclitellochaeta from 2 S%, was measured, the animals tolerated 1.25-20 S% resp. 2.5-10 S% during the time of experiment, 5 respectively 6 days. 5. The salinity preference of Aktedrilus monospermazecus from 6 S% in the field was found to be 2.5-5 S% while Marionina preclitellochaeta from 0 S%, preferred 0.2-0.3 S%. It is clear that the animals actively choose distinct salinities, at least in the laboratory. 6. The concept of stable preferences is also discussed. Experiments with Akiedrilus inonospermatecus showed that the preference for 5 S% remained even after eight days at 20 S%. [ABSTRACT FROM AUTHOR]

In terrestrial and marine shallow-water biotas the organic diversity normally shows a latitudinal gradient. Decrease of diversity is correlated with increase in latitude. FlSCHER (1960) regards the inhibiting effect on the organic evolution by the extensive climatic fluctuations on high latitudes as the predominant cause of this feature. In this paper some general aspects on the diversity of the limnic fauna are put forth, and the latitudinal variation of its taxonomic diversity is exemplified by the basommatophoran gastropods. Normally, the limnic environment is characterized by its sharply discontinuous nature in space and time. This particularly affects fauna elements with an exclusively limnic life, here called the hololitunic fauna. The other limnic fauna components are the merolimnic organisms, which spend only part of their lives in the limnic environment (most aquatic insects, some migratory fishes and many amphibians), and the endoparasites. Members of these other fauna components can easily spread by active or passive dispersal to other water bodies and therefore they are not representative when discussing the biogeographic and evolutionary effect on the fresh-water fauna by the discontinuous nature of the fresh-water body. The hololimnic fauna is characterized by a wide geographic range of the taxa. Its non-taxonomic composition is fairly uniform throughout and does hardly show any latitudinal differences. The taxonomical and adaptational differences between e. g. temperate and tropical faunas are practically missing among hololimnic faunas (if the fishes are disregarded). The hololimnic fauna is characterized by a rich intra-specific diversity, ecophenotypical and genetical. Apart from certain primary adaptations, facilitating osmoregulation and breathing in fresh water, members of the hololimnic fauna show few special adaptations. With few exceptions the secondary adaptations in this fauna help their bearers to bridge the gaps in time and space of the fresh-water habitat (features which favour hibernation, aestivation, passive dispersal and successful colonization, general euryoky). In the hololimnic fauna the evolutionary process is repeatedly interrupted due to the short duration of the fresh-water bodies, Diagramatically it can be said that a terrestrial or marine species has passed a long uninterrupted succession of generations, normally without abrupt change of environment. A hololimnic species, on the other hand, has passed numerous short successions of generations separated by abrupt change of environment. Thus the mode of evolution in all the hololimnic faunas to a certain extent conforms to that of the terrestrial and marine littoral faunas on high latitudes as interpreted by FISCHER. Consequently, on theoretical grounds the hololimnic fauna should not show the same latitudinal diversity pattern as these other faunas. The relative paucity of these faunas on high latitudes should, as far as the hololimnic fauna is concerned, have a correspondence on all latitudes. The actual situation among the limnic basommatophoran snails, a. taxonomically and geographically fairly wellknown hololimnic group, conforms to this theoretical presumption. The fishes, on the other hand, display a different picture. This is easily explained by the quite different mode of dispersal in this group. [ABSTRACT FROM AUTHOR]

In the present paper some comparative qualitative and quantitative phytoplankton investigations of brackish water and lakes situated at low levels near the coast of the Baltic Sea are summarized. The lakes (from sea level up to ca. 7 m) have recently been isolated from brackish water fjärds by the postglacial land uplift. The quantitative investigations were performed according to the Utermöhl technique; the volumetric determinations were made using the "calculated volume" method. Differences in the qualitative composition of phytoplankton mainly occurred between the brackish water area and the genuine freshwater lakes. Among the latter, lakes of pond character (Utálsviken and Ösbysjön) showed deviating features in the predominance of chrysophytes. The lakes belonging to the flada stage, viz, small lakes in connection with the Baltic and receiving sporadic influxes of brackish water, contained the largest number of species; some specific organisms were also stimulated to an enormous development in this area. The change from ice covered lake to open water is the critical time in the succession and development of phytoplankton. During the vernal water circulation after the breaking up of the ice more suitable temperature, light, oxygen and nutrient conditions occur and an increase in the standing crops was recorded in all investigated lakes with only one exception, viz, in Ösbysjön, where very large populations of bacteriophytes, euglenophytes, pyrrophytes, etc., occurred in winter. However, the highest total volumes of phytoplankton throughout the year were not always recorded in connection with the spring outburst. The flada stage was characterized by very high total volumes of phytoplankton (Fig. 3), in particular in spring and summer, in addition to the largest number of species. Studies of the vertical distribution of the phytoplankton revealed characteristic features of the lakes. In Görväln (ca. 53 m deep) the normal vernal water circulation and consequently the distribution of plankton was disturbed by a small influx of brackish water (1955-1956); in Ösbysjön (3.5 m deep) specific mud organisms appeared in winter and during a short period in summer, when very low oxygen concentrations occurred (1957-1958). In Sandãngsfjarden (5-6 m deep) three zones with very different temperature and salinity conditions as well as phytoplankton composition could be distinguished. A moderate increase in the total volumes of phytoplankton (caused by diatoms) was often recorded in autumn. In winter low values were obtained in all lakes except in Ösbysjön. Specific "cold water organisms" could be distinguished in all lakes. Because of the land uplift new lakes are formed continuously along the coast of the Baltic. The flada stage is mainly characterized by specific diatom bottom algae, large phytoplankton populations but a disharmonic developmental sequence during the year. All features characterizing this stage are apparently absent in lakes at a height of ca. 1 m above sea level: both physico-chemical conditions and the developmental sequence of phytoplankton algae are stabilized. Then several different types of lakes may be distinguished: Ösbysjön, presented in WILLÉN II and III, is an example of a "pond lake"; some remarks are also given about Lake S. Vixen (S. Sweden; 215 m above sea level), where relatively low total volume values were recorded but the same developmental sequence occurred as that in the more low-lying lakes. Some additional remarks are given about the importance of the nannoplankton in the standing crop, some little known phytoplankton algae, and some indicator organisms used in a study of the phytoplankton development in Granfjärden, Lake Mälaren, where an experiment was performed in the winter of 1958 to keep the passage to the town of Västerãs free from ice. [ABSTRACT FROM AUTHOR]

The third paper in this series deals with leaching and decomposition of birch litter (Betula verrucosa). The following results are obtained: 1 a. The ash, P, and Ca content of fresh litter is largely in agreement with the values reported in the literature. The N and K content is, however, lower than that generally found. b. The amount of water-soluble organic substances obtained after anaerobic leaching for one day is 10.7 % of the dry weight of the litter, and after 2 days 11.8%. Thereafter, a decrease sets in. c. The water-soluble inorganic substances constitute 33 % of the total inorganic substances in the litter. d. The total amount of water-soluble organic substances in fresh litter, obtained by 6 consecutive teachings of the same litter at 25°C, is 14.3 % of the original dry weight. e. The leaching of organic substances from the litter increases almost proportionally with temperature from +3°C to 90°C. f. The amount of water-soluble organic substances decreases when the litter undergoes decomposition. g. The amount of water-soluble organic substances obtained in aerobic leaching is smaller than in anaerobic leaching. As in anaerobic leaching, this amount decreases after two days with a longer duration of leaching. h. The aerobic decomposition of water-soluble substances separated from the litter is larger than the anaerobic. In both cases, most of the decomposition takes place during the first few days. 2 a. The pH rises during aerobic decomposition of litter but falls during anaerobic. b. The rise in pH under aerobic conditions is larger if the extract of fresh litter is separated from the litter during decomposition. c. When the fresh litter has been leached anaerobically 6 times (each for one day), and is thus emptied of its water-soluble substances, the rise in pH during aerobic decomposition is small. 3 a. The decomposition has been studied under both aerobic and anaerobic conditions at 25°C. After 43 days, the aerobic decomposition is about twice as large as the anaerobic. b. The decomposition of fresh litter containing water-soluble substances is larger than the sum of the decomposition of water-soluble substances and the decomposition of leached litter which has lost its original content of water-soluble substances. [ABSTRACT FROM AUTHOR]

This paper deals with the leaching and decomposition of the needle litter of spruce. The following conclusions can be drawn from the experiments. 1 a. The leaching of water-soluble organic and inorganic substances from unground needle litter of spruce takes place slowly. After one day's anaerobic leaching at 25°C, the amount of water-soluble organic substances leached from the litter is only 1% of its dry weight. If the needle litter is ground, the corresponding value is 12.5 %. b. The increase in the amount of leached organic substances with temperature is especially large at high temperatures. c. The amount of water-soluble organic substances decreases when the litter undergoes decomposition. d. The amount of water-soluble organic substances leached under aerobic conditions is smaller than that under anaerobic conditions. e. The water-soluble organic substances undergo greater decomposition under aerobic conditions than under anaerobic. In the former case, about 60 % of the organic substances in the original litter extract are decomposed after 42 days. 2 a. The pH of the Jitter extract in contact with the litter rises under aerobic conditions but falls under anaerobic. b. The rise in pH under aerobic conditions is greater when the litter extract is separated from the litter. After 3 days under aerobic conditions, the pH of the litter extract is 7.1. c. When the litter has lost part of its water-soluble substances, the rise in pH during the first days is smaller than that in litter containing all its waters soluble substances. 3. During anaerobic leaching, decomposition proceeds fairly rapidly during the first days, but after 480 days amounts to only 9% of the dry weight of the litter. The decomposition during aerobic leaching is 11.8% after 46 days. Nearly the same value is obtained for decomposition of litter in water-saturated air at 20°C. [ABSTRACT FROM AUTHOR]

This paper is a second report on studies of the phytoplankton vegetation of Lake Ösbysjön, Djursholm, performed in 1957-1958 with some additional analyses in 1959 and 1960. A comparison between the phytoplankton composition at two stations in the lake did not show any great differences in horizontal and vertical distribution. The phytoplankton development was followed daily during a week in July of 1958. Towards the end of the week some minor differences of the vertical distribution were noted due to a rising O2 deficit near the bottom. Similar stratification was also observed in the summers of 1957 and 1959, followed by an occurrence of some specific mud organisms in the plankton. A comparison between the plankton in the beginning of June during four years, 1957-1960, showed great differences both with regard to phytoplankton volume and to composition. The plankton conditions during the winter of 1958 are illustrated by percentage diagrams. The highest volume figures were recorded before the ice had disappeared from the lake and not during the spring circulation. With regard to the oxygen conditions in the lake, autotrophic and heterotrophic phases were distinguished. During these phases specific algal communities were favoured. As to the phytoplankton some characteristic features have been emphasized: appearance of several mud organisms, scarcity of diatoms and dominance of chrysophytes. Comparisons have been performed with other investigated lakes of similar character. With regard to the phytoplankton volume and composition, Ösbysjön is to be characterized as a pond lake. Some notes on the phytoplankton of Lake Ekebysjön, situated near Ösbyasjön, are given. [ABSTRACT FROM AUTHOR]

Several botanists have investigated the flora of the south bluffs, but only a few zoologists have studied their fauna. The paper presents the results of studies on certain invertebrate groups in some south bluffs in the Swedish provinces of Ångermanland and Lapland. The physiographical conditions of the south bluffs are described and temperature measurements are shown diagrammatically. As expected, the south bluffs facing south were much more favoured than mountains facing north. In spring particularly the temperature differences were very great. There were also obvious differences between the temperatures of a south bluff facing east and of a usual mountain slope facing west. The favourable temperature conditions involved early melting of the snow and insignificant frost. The list of the collected species includes 46 species. Most of them are molluscs. The mollusc material is treated statistically. There is an obvious difference between the south bluffs and other mountains as regards the dominance and constancy of their mollusc faunas; scrubs of different types are intermediate. The differences are smaller between similar habitats in Lapland. Most of the localities investigated had a great mutual affinity on account of the rich occurrence of eurytopic species. In Ångermanland the fauna of the south bluffs was of more southerly character than the fauna of other localities. Yet the dominance of the southern elements was small. There were large similarities, in this respect, between the localities investigated in Lapland and the common deciduous forests in Ångermanland. The importance of the south bluffs for the presence of certain faunal elements in Norrland is evident. Some southern elements seem to have their northernmost occurrences in such localities. A few may be relicts from post-glacial warm period (e. g. Vallonia costata and Ena obscura) while others form northern outposts of wide-spread southern species. The main part of the fauna of the south bluffs consists of very wide-spread Fennoscandian species or northern elements. [ABSTRACT FROM AUTHOR]

Measurements were made of the percent of tree leaf surface area which was consumed by animals and fungi during the period the leaves were attached as an index of minimum level of primary consumption in forests. Collections of freshly fallen leaves were made from three hardwood forests in southern Ontario, and the basal area per hectare of tree species sampled for these stands. The missing and the original area of each leaf was measured by a graph paper planimeter, and the utilization of the leaf calculated as the percentage of missing (i. e. consumed) area. These percentages varied from 3.2 for Acer rubrum to 15.0 for Prunus virginiana. The mean percentage for the 13 collections was 8.3. Utilization of a given species apparently depends on the rate of utilization for the stand as a whole, which reflects population level of the primary consumers, and may be related to leaf nutrient content. Percent utilization per stand was calculated by weighting the utilization of each species by its trunk basal area/ha. These weighted percentages were 11.7, 6.0, and 4.4. Two estimates were available from the literature of leaf loss as a percentage of total photosynthesis of 11.4 and 13.3. Using the mean of these figures, minimum estimates of primary consumption in relation to total productivity for the Ontario stands of 1.4, 0.7 and 0.5 percent were calculated. [ABSTRACT FROM AUTHOR]

Searching the literature for statistically significant effects of the population density on the sex ratio led to the following results: In animals with chromosomal and random sex determination and heterogametic males the investigated species (mostly Coleoptera and Diptera) showed as a rule no effect of crowding on sex ratio. The only exception (Drosophila pseudoobscura subgroup) showed a female sex ratio which increased linearly with density. This is a positive feed-back, which will counteract a regulation of the density. In Lepidoptera, which have a chromosomal and random sex determination and heterogametic females, Tineola is found to have the female sex ratio decreasing linearly with increasing density, and small values during crowding are rather frequent in other species of Lepidoptera. This is a negative feed back, which may contribute to the regulation of the density. This is also the case when the female sex ratio is found to decrease with increasing density in parasitic Hymenoptera, where the sex determination is chromosomal, but non-random, and in animals with phenotypical determination of the sex. In one of the latter species (the crustacean Moina) the function is perfectly linear, in other cases the linearity is more or less doubtful. In animals with chromosomal and random sex determination very small densities may result in a low female sex ratio because of the effect of delayed fertilization (the cytological mechanisms are different in homogametic and heterogametic females), and an analogous phenomenon may occur in Hymenoptera by way of arrhenotokous parthenogenesis. This may be regarded as a negative feed-back increasing the chance of fertilization when it is too small. Looking for mechanisms underlying the effect of density on sex ratio by differential mortality of the sexes it was found that papers on selection and the sex ratio were irrelevant to the problem. Attempting a mathematical model of the differential mortality of the sexes as a function of density in a population of one age group the simplest form was found to conform to the following picture; when plotted against the density the percentage survival forms a straight line for the total and two parabolas concave towards it for the two sexes (Fig. 1). This implies that the absolute survival of one sex can be expressed as a third power polynomial in the initial number of this and the other sex. (Equation 5). [ABSTRACT FROM AUTHOR]

Presents a review of several reference materials related to aquatic biology. "50 Jahre Archiv für Hydrobiologie. Eine Literatur-Analyse der Limnologie dargestellt an den Bänden 1-50, 1906-1955," by M. Scheele; "Vegetation Map of Africa South of the Tropic of Cancer," prepared by A. Aubrévile, P. Duvigneaud, A. C. Hoyle, R. W. J. Keay, et al.; "Soil Zoology in the Soviet Union," a paper presented at an All-Union Congress on Soil Zoology in Moscow, Russia from November 25-29, 1958.

The present paper deals With the marking of the moth Phyllocnistis labyrinthella with p32. Laboratory experiments were carried out with the intention of determining the concentration of the phosphoric acid most suitable. The highest radioactivity of the moth was obtained with solution containing 100 μC of p32 per ml. In this experiment the moths acquire an activity of 100000 cpm, which makes it possible to register the moth at a distance of 1/2 m. The released, activated moths in the field were recovered by means of the Geiger counter. [ABSTRACT FROM AUTHOR]

1. The study areas chosen for this work are situated in a pure stand of Douglas fir and are characterised by the extreme uniformity of tree growth and the evenness of the forest floor. The soil profile shows the "mor" type of humus formation typical of coniferous forests. The climate of the region is temperate. 2. Using an extraction technique described in a previous paper, weekly estimates of the enchytraeid population were made from April 1954 to April 1955. During this period population densities ranged from a late winter minimum of 42,000 per. sq. m to an early summer maximum of 250,000 per sq. m. 3. A detailed examination of the homogeneity of the study areas was carried out; no large scale density gradients were detected, but it is apparent that individuals in the population are aggregated. This fact has an important bearing on the statistical analysis of sample data. 4. During the routine sampling period population density was found to be positively correlated with temperature. The soil moisture content had no effect on numbers except in the litter layer where numbers and moisture content were closely correlated. This is a reflection of the high percentage of Enchytraeoides cognettii, a species highly sensitive to moisture content, in the litter layer. 5. Additional estimates of population density were made during a drought in July, August and September 1955. Densities dropped to 6,400 worms per sq. m under the influence of low soil moisture contents. 6. The species composition of the population was examined and the 3 important species (Enchytraeoides cognettii, Achaeta eiseni and Henlea sp.) were found to undergo similar seasonal changes in numbers during the routine sampling period. During the summer drought in 1955 numbers of all species were greatly reduced, and the population of E. cognettii was completely killed. 7. In N. Wales fluctuations in population density are habitually related to temperature but exceptional low soil moisture contents can have an overriding effect. This is contrasted with the situation in Denmark, recorded by NIELSEN, where low soil moisture contents during the summer habitually impose a summer minimum upon population density and prevent the response to rising temperatures in the spring. [ABSTRACT FROM AUTHOR]

The article informs that the behaviour of individual plants of certain species has been studied on permanent quadrats laid out during the period 1942-1944 in forest and hay-meadow in central Sweden. Of several interesting conclusions the most important concerned the rate of replacement of the species, both from seedlings and by branching. The rate of renewal from seedlings was found to be almost nil in many cases, and the individual plants of the species studied must have been rather old. The figures presented were preliminary on account of the short period of observation and the difficulty of deciding the extent to which the communities under study were stable or developing towards a climax. The area investigated is situated 100 km northeast of Stockholm, near the Baltic Coast. A brief description of the experimental plots was given in the preliminary paper. Comparison of the different counts from the same plots reveals relatively small differences. On most plots one species was studied. In one meadow plot, however, an attempt was made to follow the changes in the entire field vegetation, although in less detail than on the other plots.

The paper gives a short account of some hydroclimatical factors and their importance for the habitants of arctic and alpine lakes. The differences in distribution of solar energy are briefly discussed. Few examples of plankton communities in arctic and alpine lakes are given together with some remarks about the geographical distribution of plankters. [ABSTRACT FROM AUTHOR]