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The behaviour of individual plants of certain species has been studied on permanent quadrats laid out during the period 1942-1944 in forest and haymeadow in central Sweden. The results observed during the first four to six years have been published in a preliminary paper (TAMM 1948). Of several interesting conclusions the most important concerned the rate of replacement of the species, both from seedlings and by branching. The rate of replacement, particularly from seedlings, has hitherto not received due attention. Earlier investigations, and particularly those conducted in Finland, have shown that in many plant communities only a very small percentage of the seedlings ever attain the floral stage (LINKOLA 1935; PERTTULA 1941). The true rate of reproduction is unknown, however, even in the meadow community which Linkola studied so closely. In Sweden, MALMSTR6M (1949) has pointed out the great difference in the rate and type of reproduction in forest communities for the "mobile" and "equilibrium" stages, but no figures are available for the rate of replacement in these various stages. In the preliminary paper figures were presented for the death rate and the rate of reproduction by vegetative propagation of certain species. It appears as if the conditions for the seedlings were even more adverse on the plots studies here than in the case of the types of vegetation studied by the Finnish investigators. 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. Another observation of ecological interest concerned the rate of flowering of certain species in different years. Annual differences in the number of flowering individuals on the same plot were found not only for orchids (Orchis mascula and sambucina) but also for Primula veris and Sanicula europaea. It was concluded that "flowering years" occur for perennial herbs as well as for orchard

Subsurface oxygen depletion in shallow waters produced by the respiratory activities of typical "floating mat" plants (Piaropus crassipes, Achyranthes philoxeroides, and Cyperus papyrus) is of common knowledge and has been widely recognized by aquatic biologists. Important papers on the limnological role of these plants are those of LYNCH et al. (1947), BEADLE (1952), and PENFOUND (1956). Dating from the early beginnings of critical limnological studies in the United States, however, published material has minimized the role of submerged aquatic plants as regulators of oxygen available to bottom fauna organisms in lakes. Usually it is pointed out that these plants function as oxygen producers (WELCH 1952), while their shading effect and oxygenconsuming capacity has been regarded as an insignificant ecological factor of the littoral benthic environment. For the most part, this idea holds, but it is the purpose of the present paper to demonstrate a strikingly different role for Elodea canadensis (a submerged vascular plant) in a northern Colorado moun

The population densities, number of species and communities of Acari and Collembola in various moorland soils near Malham, Yorkshire, have been described by the author in other papers in this series (Wood 1967 a, 1967b). The present paper is concerned with vertical distribution in four of these sites. The soils and vegetation were described by Wood (1967a), and only a brief description is required of the four sites concerned here.

Inspired by A. POUYANNE'S and M. J. GODFERY'S investigations on the unique ways of pollination in the different species of the orchid genus Ophrys I started in 1941 an investigation of the pollination of Ophrys insectifera in Allindelille Fredskov in Zealand. The investigation extended over five years, most work was done in the years 1941, 1942, and 1949. My first task was to detect and number each plant of the year's stock of Ophrys. At intervals of two days all plants were revisited, and opening of flowers, removal of pollinia, development of germs, and other important facts concerning the pollination were noticed. The results of this investigation are given in a recently published paper (WOLFF 1950). Due to the marked paucity of pollinating insects this work, however, turned out to be much less extensive than originally conjectured. This afforded me a good opportunity of making other ecological observations on the Fly Ophrys, and since they might be of some interest, I have given them in this paper. In one single instance (distribution and biotopes of Ophrys insectifera) I have besides made a compilation of the records given in the literature, since these are extremely scattered and not easily accessible.

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.

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 schinzii) 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 ungrazed area than in a corresponding grazed one. Only if the ground, after it was abandoned became covered with Phragmites communes (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. Pe3loMe 14ccnIeqOBaHHH, KOTOPi~e IPOBOIHJIHCb B MaeHLOHe 1966 1968 rr., HMeJIH uxeimfio oripegeneHne Ka'IeCTBeHHbIX H3MeHeHHIr 4DayHbI IITHU, npOHCIIegIUHX BCJieCTBHe HOBbIX 4)OPM HCrIOJIE30BaHHS 3eMeJIBHbIX yrOAHIr, PaCrOJIO)KeHHbLX Ha 6eperax 03ep, peK H Ha MOPCKOM Iio6epe)Kbe LOXHOR LHBeIXHH. Oco6oe BHHMaHHe yaeJiqljiocb 6oJIb6noMy BepeTeHHHKy Limosa limosa L. TpaBHHiKy Tringa totanus L. 'epHo3o6HKy Calidris alpina schinzii Brehm H )KeJITOA TP5COrY3Ke Motacilla f. flava L. OHHM H3 rJIaBHbIX DaKTOPOB, OKa3bIBaBOLLHX BJIH$HHe Ha TpaHC4)opMaiHIo paCTHTeCJbHOCTH npH6pe)HbIX yqaCTKOB ABJIHeTCA IIPHMeHeHHe HOBbIX 4OPM HCfIOJIB30BaHHH nacT6Hi1. Ho3TOMy HccJiegOBaHHMie yqIaCTKH 6bIJIH nogo6paHbl TaK, 'qTo6bI npegCTaBHTb pa3HICe nepRog1I BbInBCa H 3apaCTaHHS nracT6&i1WHoIR rjioigaxH. ,Janee 6onee noJgpo6Ho HCCJIiegOBaJICH 4)aKTOp HCJIOJlb3OBaHHS 3eMejibHMIX yroqHiA no CpaBHeHHio C XapyrHMH 4aKTopaMH, BJISH1OJIIHMI Ha TpaHC4bOpMaLXHLO paCTHTeJibHOCTH. OKa3aJIOCb, 'ITO MaJIO BHOB qBjiqeTCA o611HMH gjiH iacT6HgW nOA BbIfiaCOM H 3apoc1uiHx riaCT6H1JX. Ha 3apocuem y-iacTKe BCTpeCaeTCA 6ora'qe no KaqeCTBY 4ayHa HTHLI, -1eM Ha yqaCTKe IOA BbIHacoM. ToimBKO B TOM cjiyqae, Korja IIocJIe BbIiiaca yqaCTOK 3apoc TpOCTHHKOM, He 3aMelqaJiOCb yBeJIeCeHHCe IHcjia BHAOB nTHU BbICHWKHBaioi1x IITeHIXOB. B CTaTbe o6cy)KAaeTCA TaKwe BOHPOC 0 TOM, KaKOe BJIHAHHe IOJIO)KHTeJI]HOe HJIH HeraTHBHoe OKa3aJIH Ha BHUbI ITHU H3MeHeHH5 B HCHOJlb3OBaHHH npH6peCKXb1X 3eMeJI6HbIX yrOajHi B TeMeHHe nOCIieAHHX CTa JIeT. Manuscript accepted December 1968.

This paper describes, part of an investigation in which an attempt has been made to elucidate the relationships between the growth of plants in a community and environmental factors. Here we shall deal only with the total annual growth of a plant community, and with the average concentrations of nutrients in the members of the community, within certain areas. Variations in size, in rate of growth and in nutritional status among individual plants have also been investigated, and in a further publication some relationships will be discussed between environmental factors and these variations, which are closely connected with the structure of the plant community. On account of their relatively simple structure the moss carpets often found in spruce forests were chosen for study. It was already known that these moss carpets present interesting ecological problems since STALFELT (1937 a) had observed that they obtain very little of their water requirements from the substratum. ROMELL (1939) has suggested that they obtain supplies of plant nutrients from the rain water Teachings of forest litter (needles and blueberry leaves). The material was collected from a spruce forest situated in eastern Uppland near the Baltic coast (590 52' lat. N.). The forest also contained a few pine and birch trees. Samples were taken towards the end of May and again towards the end of July from the closed community of the carpet of mosses. All samples were taken from patches where Hylocomium proliferum was dominant, and were selected from within an area 15 X 15 m, lying partly beneath the spruce crowns but also comprising a. small clearing among the trees. The field layer was mostly sparse and consisted of scattered Vaccinium inyrtillus and V. vitis idaea. The light intensities, as shown in Figs. 1 & 2

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. Pe3ioMe JaHnlbie no 6uoioeuu 6pumancKux naYKO6 U3poda Dysdera. Pogp Dysdera BKJIKoaeT OKOJO 80 BH4,OB, 6011b]lUHHCTBO H3 KOTOpbIX pacnpOCTpaHeHbI B 3anaJRHof4 EBpone H Ha no6epewxbe CpeAH3eMHoro MOpSI. HaCTOslluaA CTaTbh COqepX4HT aaHHbIe no 6HollorHH Dysdera. noJIyqeHHbIe npH TaKcoHOMHWICKHX HCCJieaOBaHHAX npeaCTaBHTeJIeft 3TO0 rpynnmI (OCHOBHas CTaTb5 Cooke, 1965). B CTaTbe npHBOAITCq qaHHbIe o6 o6-beKTax HHTaHH5I H eCTeCTBeHHbIX sparax nayKoB, o6Cy)KgaalOTCA pa3JIHlHbiTe aCfleKTbI 6HoJIornH pa3MHOweHCHH Dysdera, a HMeHHO, 6paqHinIe uirpii, oco6eHHOCTH CrIapHBaHHAT, ce3OHHaS aKTHBHOCTb R OTKJIiaKa SIHi. YaejieHOB HHMaHIe Bonpocam Me)]KBHJOBOrO cKpeIIUHBaHKA, KOTOpOe, XOTA H He BCTpetiaeTCA B npHpoge, HO MO)KeT Ha6mno0aTbCH y nayKoB, coxaepxaIIHxcs B JIa6opaTOpHbIX yCJIOBH4AX. 5Aifia, OTJIOxKeHHbIe B pe3yJlbTaTe TaKOrO CiiapHBaHH$T He)KH3HecHoco6HbI. Manuscript accepted 15 May 1965 OIKOS 16, 1-2 (1965) This content downloaded from 207.46.13.118 on Sun, 11 Sep 2016 06:03:50 UTC All use subject to http://about.jstor.org/terms Biology of British Dysdera 21

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

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 ?0.250C 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. Pe3loMe

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.

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 are 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 in 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 (57O45' N) is severe enough to have a cumulative effect on flowering date and seed germination sufficient to postpone emergence date of the seedlings beyond the critical time for their survival. Pe3IoMe Bonpoc o pacnpocTpaHeHHH Corynephorus c nescens B BeJIH4o6pHTaHHH pacc;aTPHBaeTCJR B ABYX acneKTax: Bo-fepBbIX, 3T0 BHa c orpaHHxIeHHbIM apeaJioM, BO-BTOpb6X, BejiHKco6pHTafHH1 ipeACTaBjiAeT ceBepy1io o6nacTE apeajia J aHHoro BHXqa. JlepBar npo6iieMa cBs3aHa c H3y'IeHHeM BO3HHKHOBCHHSI H pa3BHTHR A1OHHOrO jiaHAina4)Ta, B xiaCTHOCTH C BOnPOCOM o XJIHTejibHOCTH cyLLIeCTBOBaHHA BO BPeMeHH H npocTpaHcTBe OTKpbIThIX nec:IaHbIX MecTOO6HTaHHtA H HX cTa6HUnbHOCTH. B CTaTi6e o6cyxcaaIoTcJq 4)aKTopbI, onpegenimoLUe pacupeAeneHsHe Corynephorus B ceBepHoll 4acTH ero apeana. COCToaqHHe nonyJIslIHti1 Corynephorus 3aBHCHT OT riPOaYKiHIKH H pacnpocTpaHeHHH ceMAIH, a TalKxe OT YCJIOBHfi[1 popaCTaHHR3 ceM5H. PeupoxyiTHBHas cnoco6HocTb H XKHWHecnoco6HOCTb ceMS1H aOBOJ16bHO Bb6COKH. JlepHoEbI noKOSI y AaHHoro BHIAa He YCTaHOBJIeHbI. CeMeHa nocie Co3pesBHHI 110I'TH He tIYBCTBHTeJThHbl K AeticTBHIO HH43KOtI TeMnepaTypbl, OHH nonHOCTMIO c03peBaio) 'epe3 8 HeAenj1i nocxie JiBeTeHH,I. BcxoxeTT, ceM51H 3aMexursieTCR UPH TemnepaType HH)xKe 150C. BcxoxceCT CMesH B flOj1eb61X YCJIOBHIAX 3aBHCHT OT KoJIHIYeCTBa AocTynHoi BjiarH, a CKOPOCTb npopaCTaHHui 3aBHCHT OT TeMnepaTypb6. xeM fo303AHee CPOKH IO5IBJeHHSI ripopOCTKOB, TeM meHee 6naronpHsTHB, ycnoBsHi AXIR HX pa3BHTHR. OnpeaeneHa rH6eJIb npOPOCTKOB Ha pas3HbIX (aaax pa3BHTHSI. YcTaHOBjieHO, MTO KJIHMaTHIqeCK4e YCJIOBHS ceBepHee rpaHHnbi apeana Corynephorus B BenIHKo6pH4TaHH1H /57 O/45' c.i., OKO[O JIoccHMyTaf CIHIIIKOM CyPOBbI, H CPOKH UBeTeHHA paCTeHHH H nOqBneHHSI nPOPOCTKOB BbIXOAST 3a npeAejibi KPHTH'IeCKHX nepHO)AoB. Manuscript accepted February 1968.

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 Mor.

are characterized by a rather long growth period of relative idleness and it is reasonable to utilize this time for planning and calculations in order to get the largest possible amount of knowledge out of each experiment. Consequently I found it relevant to consider the suitability of a more complicated design which makes it possible to examine the effects of several factors simultaneously. Hence the subject of this paper is not only the reactions of the larvae, but also the use of complicated designs in this type of work. The design of the experiment was a 5 x 5 hyper Graeco-Latin square (FISHER, 1947). I used the square devised by Fisher and randomised it thoroughly. Having no a priori background variation, I used also rows and columns as experimental factors and it was consequently possible to test 5 factors, each in 5 steps. The randomised square and the doses are given in Table 1. (p. 66). The remaining four degrees of freedom for unexplained variation between groups are unsatisfactory for estimating the random sampling errors, and therefore further degrees of freedom had to be obtained from a within-group variation. In practice the calculation of such a complicated design presupposes the same number of larvae per group, and therefore a within-group variation could be obtained only if at least two larvae survived in each group. As the mortality in similar experiments (RASMUSSEN, 1956 a and b) was rather high, 30-50 %, the number of larvae per group was as large as 15, in order to make allowance for some non-random mortality. The plan was to use the minimum number of survivors in any group as the number of observations per group in the calculation, and reject the exceeding observations in the groups with more survivors. This rejection process, however, seemed to be problematic. If the mortality was highly dependent on the dosages, the surviving larvae in the

In attempting to survey the factors associated with the size of the standing crop of natural vegetation types, a more detailed study was made, in the late summer (September, 1953) of the soil relations of stands of Phragmites communes under various habitat conditions. The basis of the estimates differed somewhat from that used in the previous paper. Less attention was paid to the amount of average cover and more to the attempt to estimate maximal performance in each site. It was found necessary where performance was poor to use the size of isolated shoots as the criterion and under these circumstances the sample quadrats on more favourable sites were taken in representative clumps of the denser stands. As a result the weight of shoot per unit area of soil would give local maximum crop weights rather than the average cover as mean standing crop. In many cases, samples were taken where Phragmites was not completely dominant, and in at least two instances, the Rannoch Moor and Kinrara 2 sites, the shoots were scattered and of a vestigial nature, so that only one would have been found in a quadrat of 625 sq. cm., the size used. In the denser stands examined the quadrats usually contained between 7 and 9 shoots fairly constantly.

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.