Lichen Growth Rates Research Articles

A Method for Investigating Lichen Growth Rates and Succession

A Method for Investigating Lichen Growth Rates and Succession

Lichen Growth Rates in West Greenland

Photographs of a lichen-measurement station, established by Beschel at Str⊘mfjordshavn, West Greenland, indicate a Rhizocarpon geographicum growth rate of 17 to 18 mm 100 years-1 between 1958 and 1970. A radiocarbon date of 330 ± 75 years BP for a moraine at the head of Ørkendalen, which is 35 km farther east and 125 m higher than Str⊘mfjordshavn, indicates a Rhizocarpon geographicum growth rate of about 6 to 7 mm 100 years-1.These results support Beschel's previous estimates for lichen growth rates in the very continental inland parts of West Greenland and strongly support his conclusions that lichen growth rates are highly sensitive to local climate and inversely proportional to continentality. The results may alternatively be interpreted, with the aid of several assumptions and disregard for climatic differences, as representing a 100-year “great-period” growth rate of 17 mm 100 years-1 followed by a “long-term” growth rate of 2 mm 100 years-1. However, there are some severe inconsistencies in this interpretation, most notably that the largest lichen at Str⊘mfjordshavn should be well past its “great period,” but it is in fact still growing at a rate of 18 mm 100 years-1. Therefore, the slower rate of growth determined for the Ørkendalen site is most probably a function of the site's more continental climate.The question of whether the difference in growth rates between the two sites is climatically caused or is due to differential maturity of the two lichen populations could be resolved by the simple photogrammetric methods employed in this study. That is, by rephotographing more of the lichen stations established by Beschel in 1958, growth rates could be determined for the entire range of thalli diameters (ages) and environments spanned by his original photographs. Growth rates so determined for thalli of different diameters at the same site would provide a quantitative relation between growth rate and maturity (climate being a constant for any given site). Similarly, growth rates determined for thalli of the same diameter but at different sites would provide a quantitative relation between growth rate and climate (maturity being a constant in this case). Thereby, the necessary data could be provided for quantitative determination of the growth rate of Rhizocarpon geographicum as a dependent function of (a) thallus diameter (age) and (b) climate.

Lichen Growth Rates in West Greenland

Photographs of a lichen-measurement station, established by Beschel at Str0mfjordshavn, West Greenland, indicate a Rhizocarpon geographicum growth rate of 17 to 18 mm 100 years-1 between 1958 and 1970. A radiocarbon date of 330 ? 75 years BP for a moraine at the head of 0rkendalen, which is 35 km farther east and 125 m higher than Str0mfjordshavn, indicates a Rhizocarpon geographicum growth rate of about 6 to 7 mm 100 years-1. These results support Beschel's previous estimates for lichen growth rates in the very continental inland parts of West Greenland and strongly support his conclusions that lichen growth rates are highly sensitive to local climate and inversely proportional to continentality. The results may alternatively be interpreted, with the aid of several assumptions and disregard for climatic differences, as representing a 100-year great-period growth rate of 17 mm 100 years-1 followed by a long-term growth rate of 2 mm 100 years-1. However, there are some severe inconsistencies in this interpreta

Geobotanical and Geomorphological Reconnaissance in West Greenland, 1961

Lichen growth rates are used to determine glacier behavior in West Greenland in modern times where no documents are available. The vegetation and flora of the areas visited by the authors in 1961 and the plant succession on glacier forelands are described. The earliest pioneers are vascular plants and bryophytes, initially in silty pockets. Rock surfaces are invaded by algae and fungus spores which succeed after about 10 years. The first lichen to appear on loose ground is commonly Stereocaulon alpinum. When foliose or nearly fruticose species reach about 2 cm diameter, crust lichens, including Rhizocarpon spp. and Lecidea spp., can be identified. During the first seven decades the growth of Rhizocarpon spp. is slow; maximum size is attained only on moraines exceeding 1,000 years. Direct comparison of lichens appearing in photographs taken on

Experimentell-ökologische Untersuchungen an Flechten der Negev-Wüste: IV. Wachstumsmessungen an Caloplaca aurantia (Pers.) Hellb.

During a period of c. 5 years growth rates of 13 thalli of Caloplaca aurantia (P ers .) H ellb . var. aurantia P oelt were measured in the highland of the Central Negev Desert near Avdat. An average annual radial rate of marginal growth of 0.68 mm was determined by direct measurements and of 0.56 mm by calculation from increment of thallus surface area. This growth equals medium growth rates of crustose epipetric lichens from other climatic regions and shows the good adaptation of the metabolism of Caloplaca to the specific conditions of the desert habitat. Annual productivity of Caloplaca amounted to c.10.4% of a young thallus. This value obtained by direct growth measurements confirms former calculations of annual lichen productivity in the Negev which were made from CO 2 gas exchange measurements in the field.

Growth Rates of Important Reindeer Forage Lichens on the Seward Peninsula, Alaska

Cladonia alpestris, C. rangiferina and C. sylvatica may comprise 75-90% of all lichens eaten by reindeer. Their growth rates must be known to determine the carrying capacity, rates of recovery and patterns for rotational grazing of reindeer rangelands. Data from two sites near Nome and a third near Koyuk show the annual linear rates of growth of these three species to be 5.0, 5.3 and 5.4 mm respectively. These averages exceed those of northern Canada and some areas in the USSR. C. rangiferina reaches the podetium renewal period in 5.9 yr, or in almost half the time required by the other two species.

Studies of Growth Rates of Corticolous Lichens on Long Island, New York

The growth rates of several corticolous lichens particularly Parmelia sulcata, P. caperata, and Lecanora caesiorubellawere determined by a tracing method on acetate sheets. Rates similar to those determined by other workers for related lichens were detected. Climate was found to have a strong effect on the annual growth rates. The slow rate of growth of lichen thalli has drawn the interest of many workers. Until recently, most studies were done on saxicolous species and few concerned bark lichens. The present investigation of lichens growing on oaks was part of a general study of the lichen vegetation of Long Island. The data here are admittedly only a very small addition to a growing body of growth rate information which we hope will some day allow us to understand better the autecology and community dynamics of lichens.

Studies of Growth Rates of Corticolous Lichens on Long Island, New York

Studies of Growth Rates of Corticolous Lichens on Long Island, New York

GROWTH RATES OF CLADONIA ALPESTRIS, C. MITIS, AND C. RANGIFERINA IN THE TALTSON RIVER REGION, N.W.T.

Data on the growth rate of lichens are essential to the understanding of the carrying capacities of rangelands used by caribou and reindeer in Canada. Recent Russian literature suggests fruticose lichens have three growth stages. The first stage is one of podetium accumulation. During the second stage, accumulation rate and decomposition rate are similar, while, in the third stage, decomposition of the Podetium is more rapid than accumulation. In the Taltson River region, the average annual linear growth rates of Cladonia alpestris, Cladonia mitis, and Cladonia rangiferina as determined by dividing the number of joints on the living podetium by the height of the living portion of the podetium, are 3.4, 3.6, and 4.1 mm, respectively. These rates are less than those reported from Russia, Newfoundland, and northern Saskatchewan.

Studies on Lichen Growth Rate and Succession

Studies on Lichen Growth Rate and Succession

First Report on Lichen Growth Rate and Succession at Aton Forest, Connecticut

First Report on Lichen Growth Rate and Succession at Aton Forest, Connecticut

First Report on Lichen Growth Rate and Succession at Aton Forest, Connecticut

First Report on Lichen Growth Rate and Succession at Aton Forest, Connecticut