Showing papers in "Journal of Ecology in 1956"

On the Chemical Composition of Some Waters from the Moor House Nature Reserve

Abstract: The analysis of bog waters has a two-fold value. Firstly, it is of some intrinsic interest to elucidate the chemical composition of waters isolated from the mineral soil by organic deposits, and deriving their entire mineral supply from atmospheric precipitation. Secondly, the poverty of raised and blanket bogs in mineral nutrients is undoubtedly an important factor in determining their floras; and vegetation patterns can often be associated in a general way with water composition. This paper records the amounts of eleven constituents in various natural waters from the new Pennine Nature Reserve at Moor House - chiefly from pools on the blanket peats at Bog Hill, now under intensive investigation by the Nature Conservancy. DESCRIPTION OF THE AREA Moor House lies at an altitude of about 1800 ft. (550 m.) in the northern Pennine uplands, with a rainfall of about 64 in. (162 cm.), an average annual temperature of 44? F. (6.7? C.) and an average relative humidity of 86 per cent (all data for 1953 only). It is surrounded by moorland and blanket bog vegetation, on peat overlying drift or carboniferous rock with limestone bands. Burning and grazing have affected the plant communities, which in general resemble those described by Pearsall (1941) from the Stainmore district a little to the south. Among the least disturbed areas is Bog Hill, a slight elevation blanketed by deep peat and bearing a community dominated by Sphagnum acutifolium (agg., including rubellum and nemoreum), Calluna vulgaris and Eriophorum vaginatum, with Trichophorum caespitosum locally abundant. The Sphagnum cover is fairly continuous, with several small pools dotted about its surface. These most frequently contain Sphagnum cuspidatum and Eriophorum angustifolium, with the alga Chlorobotrys sometimes forming a scum at the bottom. In certain pools Drepanocladus fluitans is quite plentiful, in others the liverwort Gymnocolea inflata. Sphagnum papillosum is often abundant at the pool margins. METHODS Water samples were obtained on two occasions in 1954, following a dry spell (May 18th) and during wet weather (August 2nd). The bog pools sampled ranged in size from about 1 to 15 ft. (0.3 m. to 4.5 m.) across, and up to about 18 in. (46 cm.) deep. Collections were made and stored in polythene bottles, the waters being filtered through Whatman 541 papers (washed with three volumes of distilled water and one volume of sample) within a day or two of collection. pH was determined by glass electrode, and specific conductivity by a bright platinum cell and Mullard bridge. Calcium and magnesium were estimated by versenate titration with ammonium purpurate and eriochrome black T as indicators; samples coloured by humus were evaporated to dryness with a few drops of hydrogen peroxide and taken up in dilute hydrochloric acid. Sodium and potassium were measured by EEL flame photometer,

The mist oasis of erkwit, sudan

Abstract: Topography and geology The Erkwit plateau lies at the edge of a steep escarpment dropping abruptly (2000 ft., c. 600 m.) to the Red Sea plains. At the northern boundary are Jebel Nakeet (3921 ft., c. 1176 m.) and Jebel Essit (3810 ft., c. 1143 m.). The two jebels drop to Khor Dahand which separates the Erkwit oasis from the barren hills on the other side of the Khor. At the eastern boundary is Jebel Sela (4244 ft., c. 1273 m.) which is the highest evergreen mountain of the district. At the southern boundary are Jebel Tatasi (3967 ft., c. 1190 m.), J. Lagagribab (4030 ft., c. 1209m.) and Jebel Auliai 3970 ft., c. 1191 m.) which are separated, by Khor Amat, from the barren mountains further south (J. Erbab, 5077 ft., c. 1523 m.). At the western boundary are J. Hadast (3826 ft., c. 1147 m.) and J. Mashokriba (3710 ft., c. 1113 m.) which drop to Khor that separates the Erkwit plateau from the desert plains to its east. The plateau and the hills arising on its top are built of basement complex rocks: gneiss, basalt, granites, shales, marble; etc. Several khors (ephemeral water-ways) dissect the plateau. The khors usually contain alluvial deposits of different depth into which holes are dug to provide fresh water supplies. Permanently running water is found in Khor Harasab and Khor Amat. Calcareous deposits are found on the bot-

Acidity, specific conductivity and calcium content of some bog and fen waters in northern Britain

Abstract: In recent years the chemical analysis of bog and fen waters has provided much information of value in characterizing the different types of wet habitats in Fennoscandia (see for example Kotilainen, 1928; Kivinen, 1935; Witting, 1947, 1948, 1949; Sj6rs, 1950; Gorham, 1950). A somewhat different approach has been employed by Webb (1947). With the aim of obtaining similar information for bogs and fens in the north of Britain, water samples were collected from various sites in the English Lake District and in Scotland during dry weather in September of 1952. Analyses for pH, specific conductivity and calcium were carried out as soon as possible after collection.

The nature and origin of the soils over the cornish serpentine

Abstract: The principal types of heath community found upon serpentine rock on the Lizard peninsula, Cornwall, England, and some of the features, so far as they affect plant growth, of the correlated soils have been described by Coombe and Frost (1956). In their paper little consideration was given to the soils as pedological entities nor was it considered whether the heath types, each with its characteristic soil, can be ranged either in a developmental series in time or a vegetation-soil catena in space (cf. Milne, 1935; Morison et al., 1948; Balme, 1953). Before going further it is necessary to examine the assumptions that the parent material of the soils which occur over the serpentine is (i) uniform, and (ii) is in fact the serpentine itself, assumptions which are basic to any hypothesis of a developmental series of soils and which would affect the interpretation of any physiographic complexes of vegetation and soil. Flett (1946) assumes more than once that the serpentine weathers to give at least some of the soils upon it. For example: 'On the surface of the Lizard platform there are practically no deposits except the products of the decomposition of the subjacent rocks. As this part of England was never covered by moving ice-sheets there is a complete absence of material transported from a distance by glacial action' (loc. cit., p. 5). 'The unmodified serpentine of the downs yields a yellow or buff clay full of weathered blocks; this soil is shallow and the bare rock projects or is everywhere near the surface. The ferruginous clay is almost impermeable to water and after heavy rains the surface of the downs is covered with water which slowly drains away. In a few places the serpentine is decomposed or disintegrated to a depth of several feet, but the soil is sterile' (loc. cit., p. 174). The 'ferruginous clay' is probably the soil of 'Tall Heath' (Erica vagans-Schoenus heath) and the sterile, deeper soil that of 'Short Heath' (Agrostis setacea heath). Coombe and Frost also assumed at first that the soils were derived from the serpentine, since areas were deliberately avoided where concealed intrusions of other rocks (e.g. the granite-gneisses), or recognized thin deposits of sedimentary material (e.g. the Pliocene Crousa gravels), or windblown shell sand (e.g. near Kennack Sands) clearly contributed to the parent material. Since the areas selected for study have never been cultivated (at least within historic times) or enclosed, the complications due to the carting and spreading as fertilizer of shell sand or rotted hornblende schist or granite-gneiss do not arise. However, the interpretation of the series of soils of increasing depth and acidity from 'Rock Heath' (Festuca ovina-Calluna heath) through 'Mixed Heath' (Erica vagans-Ulex europaeus heath) to 'Short Heath' (Agrostis setacea heath) as a simple

Studies of the Development of Woodland Conditions Under Different Trees: IV. The Ignition Loss, Water, Carbon and Nitrogen Content of the Mineral Soil

Abstract: The ground flora, surface humus and timber formed in plantations are in part derived from the underlying mineral soil, and their weights are largely dependent upon the type of tree species selected for planting. Earlier investigations have indicated that some soil conditions are modified in various ways by different tree species. In the present paper an account is given of the ignition loss, water, carbon and nitrogen content of the mineral soils after afforestation with monoculture stands. Three

Acidity and Specific Conductivity Measurements in Some Plant Communities of the New Forest Valley Bogs

Abstract: The importance of chemical factors in differentiating the plant communities of bogs and fens has long been recognized, especially in Fennoscandia, where several studies have been made of the acidity and specific conductivity of bog and fen waters (refs. in Sj6rs, 1950). The present work is an attempt to extend this method of investigation to some southern English valley bogs, which have had little attention since their brief description by Rankin over thirty years ago (see Tansley, 1911).

Some preliminary observations on the ecology of pit heaps

Abstract: This preliminary account of the ecology of pit heaps is based on work carried out in the Nottinghamshire-Derbyshire coalfield and to a lesser extent in the south Yorkshire coalfield. The investigation was carried out in the attempt to discover what factors lead to the establishment of vegetation on pit heaps and the types of plant involved. In addition detailed studies of particular plants were made with reference to their capacity to stabilize pit banks. METHODS Although Hope-Simpson (1940) has shown that subjective estimates of plant frequency vary considerably, this method was used in nearly all the work reported here because it seemed the best for rapidly estimating the frequencies of plants growing on a large number of heaps. The final list of plants presented here is derived from the pooled information of frequencies of plants from each of forty heaps. In five of the heaps studied the numbers of shoots found in twenty half-metre quadrats were counted, the quadrats being randomized on the heaps as follows. A stone was thrown and where it landed the compass points were roughly drawn out. Four random numbers were taken from Fisher and Yates's Statistical Tables (1953) and these were measured out in feet, one in each compass direction, and the quadrats put down. This was repeated until twenty quadrats had been made. A similar procedure was employed for randomizing the glass plates used for trapping wind-borne seeds. Each stem in a quadrat was counted as a single plant. In the case of tuft formers such as Festuca ovina each small bunch of grass was counted as one shoot. The age of the five heaps studied in detail was supplied by the surveyors of the National Coal Board, East Midlands Division. It was decided that the date of the last tipping on the particular part of the heap studied should indicate the age. The material making up the heaps was of similar geological origin and the greater part of it came from the Deep-hard, Deep-soft horizon. (I am indebted to the Chief Surveyor, National Coal Board, East Midlands Division, for this information.) Pit heaps usually consist of mixtures of: (a) Bind, an indurated clay mixed with oxide of iron; (b) Fireclay; (c) Sandstone; (d) Ironstone and (e) Small amounts of clay and boiler ash. This waste is tipped into heaps by means of overhead buckets or by waggons; often pit heaps have been on fire and this has restricted for a period the growth of vegetation; such heaps can often- be recognized by their red colouration. It was decided to classify the visible fragments of pit heaps according to size as shown below. Ten metre quadrats were taken at random on each heap to estimate the size of fragments, which were classified as: (a) fine, where most of the material ranged *Now at the Manchester Grammar School.