No description available.

Tree-ring studies started in the Palaeoecology Laboratory in 1968. The impetus for the work was provided by the large amount of sub-fossil oak and pine that was brought to our notice by archaeological excavation and road construction. Sample preparation and ring measurement techniques were developed and crossdating was demonstrated in some of the sub-fossil material. A program of field collection was started and a research assistant employed on the laboratory treatment of samples. Good crossdating over a wide area was then established for both oaks and pines, demonstrating an overriding climatic influence on tree growth even under bog conditions. A number of floating sequences in excess of 500 years length have been constructed and timbers have been found from every half millenium back to 8000 radiocarbon years before present. Over 1400 timber samples have been collected and a large amount of material remains to be collected.

No description available.

The tree-ring characteristics of material used in a 35-tree, 265-year modern oak chronology from a site in North Wales are discussed. Three methods of standardisation are compared and temporal variation in chronology statistics examined. A response function using rainfall data from a station very close to the tree site related 45% of the chronology variance to climate and 73% to climate plus prior growth.

A pilot investigation of 11 trees from London parks has shown that elm (Ulmus) is suitable for dendrochronology and dendroclimatological analysis. Ten trees are shown to crossdate well and form the basis of a London group elm chronology for the years 1900-1971; chronologies derived from fewer trees cover the period 1840-1971. Correlations with monthly climatic variables and seasonal rainfall and soil moisture totals are described. Response functions for the relationship between the London elm chronology and precipitation and temperature recorded at Kew demonstrate the direct relationship between ring width and precipitation during the growing season and during the previous autumn and early winter (September to December), an inverse relationship to rainfall the previous summer; above average temperature during the previous autumn leads to above average ring width but there is an inverse relation between ring width and temperature during March and April at the commencement of the growing season.

Six modern oak tree-ring chronologies from Ireland are presented. All are from planted or from disturbed-natural woodland of Quercus petrea. The final chronologies were tested for climate content by the response function method. The results range from 5% to 52% of the chronology variance explained by temperature and precipitation of a 14 month period during and prior to the growing periods. The relationship between these figures and the site and chronology details are examined. The relationship of the individual chronologies to each other is examined and the hypothesis put forward that Ireland can be considered as a single tree-ring area from a dating viewpoint.

Tree-ring samples from bur oak in eastern Nebraska are analyzed and found suitable for dendroclimatic analysis. Four methods of standardization are used to develop four 233-year master chronologies. ANOVA statistics and response functions based on each chronology are examined. Response functions based on both single- station and regional climatic data are analyzed and compared. The information provided by response function analysis varies considerably depending upon choice of standardization option, number of eigenvectors extracted, and generalization of climatic data (station or region). A response function based on the polynomial chronology and 46 years of regional climatic data relates 53.4% of the chronology variance to climate and 70.4% to climate plus prior growth. The bur oak master chronology provides valuable proxy evidence for periods of moisture stress experienced during exploration and settlement of eastern Nebraska.

Eight modern oak tree-ring chronologies are presented in index form. The sites are in Scotland and England. Chronology statistics including signal-to-noise ratios are presented, the latter ranging from 3.6 to 13.2. From calculations of response functions, the percent variance attributable to climate over a 14 month period before and including the growing season was found to range from 33 to 72 %. Classical criteria of site selection were shown to bear little relation to the final variance due to climate in the chronology.

Sixteen modern Nothofagus solandri tree-ring chronologies, developed from sites near the alpine timberline, South Island, New Zealand are presented. The statistical properties of the chronologies are similar, having high mean sensitivity values (mean of 0.34), moderate autocorrelation values (mean of 0.50), and high common variance values (mean of 42 %). However, the chronologies are mainly less than 300 years in length. Examination of interchronology variation suggests that the similarity between two chronologies decreases with increasing distance. It is concluded that these chronologies offer considerable potential for reconstructing palaeoclimates, especially palaeotemperature.

Spline functions were examined and compared with conventional polynomials for use in filtering nonclimatic variance from tree-ring width series. Both types of curve were fitted to ring-width series exhibiting particularly marked effects of competition and release from competition with neighboring trees during the last 100 years. Available climatic data from that interval were used to statistically evaluate the capabilities of each type of function for removing nonclimatic effects and preserving the climatic signal. The results suggest that both types of function can be used successfully for those purposes, though in the presence of extremely rapid changes in growth rate due to a sudden release from competition it may be necessary to divide the ring-width series into two segments and fit a separate curve to each segment. Tightly-fit polynomials seem to be about as effective as splines, but are less desirable from a computational point of view as, for example, when the magnitude of the (negative) exponents of the coefficients exceeds computer capacity. Further, a spline function can be prescribed from its frequency-response characteristics, so it is possible to specify in advance the extent to which it will filter out any potential climatic cycles.