Lichen growth rates on glacier forelands in southern norway: preliminary results from a 25‐year monitoring programme

2010 ◽  
Vol 92 (1) ◽  
pp. 19-39 ◽  
Author(s):  
Hazel E. Trenbirth ◽  
John A. Matthews
Keyword(s):  
Growth Rates ◽  
Monitoring Programme ◽  
Preliminary Results ◽  
Southern Norway ◽  
Lichen Growth

scholarly journals Observations on the increase in size at moulting in the lobster (Homarus vulgaris M.-Edw.)

1958 ◽  
Vol 37 (3) ◽  
pp. 603-606 ◽  
Author(s):  
H. J. Thomas
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growth Increment ◽  
American Lobster ◽  
Limited Data ◽  
Preliminary Results ◽  
Home Department ◽  
The Individual ◽  
Marine Laboratory

A knowledge of growth rates is a pre-requisite in estimating the effect of fishing upon the available stocks. In Crustacea, where there is no known means of establishing accurately the age of the individual, the importance of measuring the growth rate is increased whilst its determination is made more difficult. In Homarus vulgaris some experiments were undertaken by Dannevig (1936), and Wilder (1953) gives considerable data for the American lobster. Results suggest that the growth increment is not uniform in all latitudes. Experiments to augment the limited data available for H. vulgaris and to establish the increase in size at moulting in local lobster stocks were therefore undertaken by the Marine Laboratory of the Scottish Home Department at Aberdeen. A statement of some preliminary results was given in Report on the Fisheries of Scotland (Lucas, 1957, p. 58).

scholarly journals Competing kinematic dynamo mechanisms in rotating convection with shear

2010 ◽  
Vol 6 (S271) ◽  
pp. 239-246 ◽  
Author(s):  
Michael R. E. Proctor ◽  
David W. Hughes
Keyword(s):  
Growth Rates ◽  
Convective Flow ◽  
Flow Fields ◽  
Velocity Shear ◽  
Dynamo Action ◽  
Preliminary Results ◽  
Rotating Convection ◽  
Kinematic Dynamo

AbstractFollowing earlier work by Hughes & Proctor (2009) on the role of velocity shear in convectively driven dynamos, we present preliminary results on the nature of dynamo action due to modified flows derived by filtration from the full convective flow. The results suggest that filtering the flow fields has surprisingly little effect on the dynamo growth rates.

scholarly journals 595 PB 173 `HASS' AVOCADO PHENOLOGY IN CALIFORNIA - PRELIMINARY RESULTS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 517c-517 ◽  
Author(s):  
P. W. Robinson ◽  
M. V. Mickelbart ◽  
M. L. Arpaia
Keyword(s):  
Root Growth ◽  
Growth Rates ◽  
Vegetative Growth ◽  
Growing Season ◽  
Phenological Model ◽  
Preliminary Results ◽  
Hass Avocado

Measurements of flowering, yield, vegetative and root growth were begun in Spring 1992 to establish a phenological model for `Hass' avocado. Although rootstock (Thomas', Topa Topa', Duke 7' and `D9') did not affect the timing or intensity of bloom, differences in yield were observed. Flowering occurred in March - April in both years, although the intensity of bloom in 1993 was drastically reduced due to an extremely heavy 1992-93 crop. Vegetative flushes occurred in April (following bloom) and July in both years. In 1993, however, cumulative growth was ca. 10-fold greater. Rootstock did not affect the timing or intensity of vegetative growth in either year. In both years, vegetative growth preceded root growth. In 1992, there were no differences detected in the timing or intensity of root growth related to rootstock. In 1993, however, the `Topa Topa' rootstock produced more roots throughout the growing season. The timing and intensity of root growth during the spring flush were similar in both years. During Fall 1993, root growth rates, however, were consistently higher than those observed in 1992. Additionally, while root growth ceased in November 1992, roots have continued to grow through January 1994.

scholarly journals Lichen Growth on an Active Medial Moraine, Jotunheimen, Norway

1973 ◽  
Vol 12 (65) ◽  
pp. 305-313 ◽  
Author(s):  
J. A. Matthews
Keyword(s):  
Population Dynamics ◽  
Rhizocarpon Geographicum ◽  
Southern Norway ◽  
Lichen Growth

AbstractAbundant specimens of lichens, includingRhizocarpon geographicum, are reported from an active medial moraine on Storbreen, southern Norway. The size and distribution of two crustose and two foliose species are described. Inferences are made regarding the age, origin and population dynamics of the lichens. Some implications of the observations for lichenometric dating and use of lichens as indicators of moraine stability are discussed.

Sizes and Growth-Rates of Thalli of the Lichen Rhizocarpon Geographicum on the Moraines of the Glacier De Valsorey, Valais, Switzerland

1983 ◽  
Vol 15 (3) ◽  
pp. 249-261 ◽  
Author(s):  
M. C. F. Proctor
Keyword(s):  
Growth Rates ◽  
Radial Growth ◽  
Growth Curves ◽  
Field Measurements ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Rhizocarpon Geographicum ◽  
Constant Rate ◽  
Maximum Parameters ◽  
Lichen Growth

AbstractMeasurements of thalli of Rhizocarpon geographicum on the recent moraines of the Glacier de Valsorey and their surroundings are considered in relation to thallus growth rates and colonization following glacial recession. Photographs taken in 1975 and 1979 show that up to c. 3.5 cm diam the relation of maximum growth-rate to thallus size is approximated by a growth curve of the kind derived by Aplin and Hill, rising asymptotically towards a constant rate of radial growth (here c. 0.5 mm year−1). Growth-rates of many individual thalli fall well below the maximum. Parameters of the fitted growth curves are used to construct curves of thallus radius against time. Taken in conjunction with the field measurements these suggest two main phases of colonization, one from about 1880 to 1910, and one from about 1930 onwards. Some general considerations relating to lichenometry and lichen growth curves are discussed.

Use of 14C/C Ratios to Provide Insights into the Magnitude of Carbon Turnover in the Crustose Saxicolous Lichen Caloplaca Trachyphylla

2002 ◽  
Vol 34 (2) ◽  
pp. 169-179 ◽  
Author(s):  
G. Bench ◽  
B. M. Clark ◽  
N. F. Mangelson ◽  
L. L. St. Clair ◽  
L. B. Rees ◽  
...  
Keyword(s):  
Growth Rates ◽  
Radial Growth ◽  
Total Carbon ◽  
Simple Explanation ◽  
Carbon Turnover ◽  
Fixed Carbon ◽  
The Past ◽  
Annual Carbon ◽  
Insight Into ◽  
Lichen Growth

Abstract14C/C ratios in samples from radial transects across individual thalli of Caloplaca trachyphylla collected at two sites were measured and the results used to investigate whether 14C/C data might provide some insight into the magnitude of carbon turnover in this lichen species. The 14C/C data suggest that significant internal recycling/translocation of carbon is unlikely in the sampled thalli. However, converting the 14C/C data for the larger intact thalli sampled at each site to calendar years, using the atmospheric ⊃14C record, does not yield constant or even monotonically varying growth rates. Since crustose lichen growth rates are constant or decrease with thallus size, and since the 14C/C data from these larger thalli show a relatively small spread in 14C/C data values compared to the Northern Hemisphere atmospheric ⊃14C record over the past 50 years, the 14C/C data suggest that carbon turnover may be occurring. Carbon turnover was modelled starting with the atmospheric ⊃14C record. Turnover was incorporated so that for each year in the record a constant percentage of the total carbon was lost annually and replaced by new photosynthetically fixed carbon with a 14C/C ratio equal to that of the contemporary atmosphere. The 14C/C data from the radial samples were then converted to a calendar year using the model record. Constant annual carbon turnover values of 0, 0·5, 1, 1·5, 2, 2·5, 3, 3·5, 4, 4·5, 5, 5·5, 6, 7, 8, 9, 10, 15, 20, 25 and 50% were modelled. Carbon turnover values between 3 and 6% created ⊃14C model records that when applied to 14C/C data from the thalli produced constant radial growth rates that were: (1) identical for all lichens at a given site, and (2) independent of lichen size at a given site. The 14C/C data further indicate that annual carbon turnover in this species of lichen is <10%, independent of the nature of thallus radial growth. The data and modelling suggest that carbon turnover might provide a simple explanation for the 14C/C data from the thalli and might explain the discrepancies between the standard atmospheric ⊃14C record and the 14C/C ratios observed in C. trachyphylla.

Lichenometric dating using Rhizocarpon subgenus Rhizocarpon in the Patagonian Andes, Argentina

2009 ◽  
Vol 71 (3) ◽  
pp. 271-283 ◽  
Author(s):  
Irene Adriana Garibotti ◽  
Ricardo Villalba
Keyword(s):  
Tree Ring ◽  
Growth Rates ◽  
Growth Curves ◽  
The Past ◽  
Glacier Fluctuations ◽  
Andean Cordillera ◽  
Latitudinal Difference ◽  
Patagonian Andes ◽  
Over Time ◽  
Lichen Growth

AbstractThis study represents the first attempt to develop and apply lichenometric dating curves of Rhizocarpon subgenus Rhizocarpon for dating glacier fluctuations in the Patagonian Andes. Six glaciers were studied along the Patagonian Andes. Surfaces of known ages (historical evidences and tree-ring analyses) were used as control sites to develop indirect lichenometric dating curves. Dating curves developed for the studied glaciers show the same general logarithmic form, indicating that growth rate of subgenus Rhizocarpon decreases over time. The strong west–east precipitation gradient across the Andean Cordillera introduces statistically significant differences in the growth curves, with faster growth rates in the moist west sites than the drier eastern sites. Latitudinal difference among the studied glaciers does not appear to be a major factor regulating lichen growth rates. Therefore, we developed two lichenometric curves for dating glacier fluctuations in wetter and drier sites in the Patagonian Andes during the past 450 yrs. Application of the developed curves to moraine dating allowed us to complement glacial chronologies previously obtained by tree-ring analyses. A first chronosequence for moraine formation in the Torrecillas Glacier (42°S) is presented. Our findings confirm the utility of lichenometry to date deglaciated surfaces in the Patagonian Andes.

MR2251-178: Preliminary results of an X-ray monitoring programme

1985 ◽  
Vol 40 (3-4) ◽  
Author(s):  
GC Stewart ◽  
KA Pounds ◽  
VA Stanger
Keyword(s):  
Monitoring Programme ◽  
X Ray ◽  
Preliminary Results
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