Frost Cracks Research Articles

Ein aufgedecktes würmperiglaziales Frostspalten-Polygonnetz bei Gütersloh

Ein aufgedecktes würmperiglaziales Frostspalten-Polygonnetz bei Gütersloh

STUDIES IN FOREST PATHOLOGY: XII. DECAY OF WESTERN HEMLOCK IN THE UPPER COLUMBIA REGION, BRITISH COLUMBIA

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the Upper Columbia region has shown that decay losses are excessive, amounting to 52 and 74% in terms of cubic and board foot computations respectively. The logs of 833 hemlock on 36 sample plots located in mature timber were analyzed in detail. Twenty-six decay-producing fungi have been isolated. Sixty-two per cent of the total decay was attributed to Echinodontium tinctorium Ell. & Ever. and 25% to Fomes pini (Thore) Lloyd. Considerable variation in the fungi responsible for decay was encountered intraregionally. Stand defect losses varied from 38 to 71%. Some of this variation could be predicted on the basis of the site index determinations of hemlock. Relative to the total incidence and importance of decay, Echinodontium tinctorium decreased and Fomes pini increased in significance with increasing site quality. Sporophores, scars, dead tops, large rotten branches, swollen knots, frost cracks, forked trees, and trunk infections of mistletoe were classed as indicators of significance in relation to hidden defect. Living trees, classed as Suspect or Residual depending on the presence or absence of one or more reliable indicators of defect, were found to differ appreciably in average defect. Within each of the preceding classes decay increased progressively with increasing diameter and decreasing site quality. Immature hemlock was found to be susceptible to appreciable decay and mature stands reached an advanced stage of deterioration at 250 years. Multiple correlation analyses between percentage of decay, site, age, and the relative percentage of Residual trees weighted by volume permitted an estimate of total stand defect within ± 7%.

STUDIES IN FOREST PATHOLOGY: XIII. DECAY IN SUGAR MAPLE IN THE OTTAWA–HURON AND ALGOMA EXTENSION FOREST REGION OF ONTARIO

Decay results in appreciable losses in sound wood volume in sugar maple (Acer saccharum, Marsh.) timber in the Ottawa–Huron and Algoma Extension Forest region of Ontario. Seventy-four per cent of 606 sample trees had some measure of decay. Twenty-eight fungi were found to be associated with decay in living trees. The most important of these are Armillaria mellea (Vahl ex Fr.) Quél., Polyporus glomeratus Peck, Ustulina vulgaris Tub, Fomes connatus (Weinm.) Gill., Hydnum septentrionale Fr., Corticium vellereum Ell. & Crag., Pholiota spectabilis Fr., and Fomes igniarius (L. ex. Fr.) Gill. Several species previously unreported in the literature were found to be associated with decay in sugar maple in Ontario. Armillaria mellea is the most serious butt-decay fungus and P. glomeratus is the most important trunk-rotting species. Frost cracks are the most important courts of entry for decay fungi. Various discolorations occur in sugar maple. The average extent of decay in living trees is estimated according to the occurrence of sporophores of F. connatus, F. igniarius, H. septentrionale, and U. vulgaris. The incidence and volume of decay increased progressively with age and diameter. One hundred and nine species of Basidiomycetes are tabulated as occurring on living and dead sugar maple in Ontario.

DAMAGE TO PINUS RADIATA BY CLIMATIC AGENTS

SUMMARY From observations made, principally in the Australian Capital Territory, damage to Pinus radiata (Monterey pine) caused by various climatic agents is described. Low temperatures are considered to be responsible for needle discoloration in winter and dead tips and needles in certain cases in young trees, small frost cracks, frost rings and strangulation. Strangulation appears to be a peculiar extension of the same type of damage as that which results in frost rings. It often causes death of the bark and cambium in a girdle near the base of the trunk and is followed by symptoms of ringbarking and in many cases by the death of the tree. High temperatures are thought to cause sunscorch resulting at times in extensive lesions, while drought appears to be responsible for excessive casting of needles, and some dying in leading shoots. Hail and snow cause only minor damage in the areas in which Monterey pine has been planted in the Australian Capital Territory, but there is evidence to show that the speci...

A Cambridge Pleistocene Climate

MR. T. T. PATERSON'S demonstration of the ’frost cracks’ in the Travellers’ Rest pit at Cambridge1 affords a valuable clue to a Pleistocene climate of that region. The presence of permanently frozen ground in England within Pleistocene times has been suspected, but proof has been wanting. ’Frost cracks’ in active formation are occupied by wedges of ice and they can only attain a considerable width in ground which remains frozen for many years. E. de K. Leffingwell considered the ice wedges in cracks in northern Alaska to have grown by successive annual increments of a few millimetres and he estimated that the wedges, which are up to three metres across, had taken 500–1,000 years to form2. Some of the Travellers’ Rest fissures are nearly two metres across and they indicate a prolonged period of low temperatures.

The effects of frost action and solifluxion around Baffin Bay and in the Cambridge District

These studies constitute part of the geographical results of the Wordie Arctic Expedition, led by Mr. J. M. Wordie of St. John's College, Cambridge, to Melville Bay and the east coast of Baffin Land in the summer of 1934. It was found that some of the arctic soil forms had strong similarities to structures observed in the Pleistocene gravels of the Cambridge area, and that, treated together, these forms and structures would throw new light on the mechanics involved in their formation. The studies are divisible into three portions: frost cracking, polygonal structures, and solifluxion. I. Frost Cracking Travellers in northern and eastern Siberia report that the tundra, in places, is scarred and seamed by ramifying linear depressions flanked by low ridges, the depressions being marked out by a darker growth of mosses, generally interlacing to form roughly polygonal features many feet across. They have not, so far as is known, been excavated (Sukatchev 1911, Nikoroff 1928). Leffingwell (1919) observed frost cracks occurring in Alaska only in “muck”, though Smith (1909, p. 272), writing on the Nome deposits, noted a “series of ramifying streaks of a black peaty material cut in irregular directions across the layers of sand and gravel”, which streaks he attributed to frost cracking. Leffingwell (1919, p. 211) also noted “frequently straight lines leading across the gentle undulations of sandspits”, though he saw no polygonal forms in such places. However, his classic treatment of the theory of the formation of ground ice led him to generalize on