Frost Hollows Research Articles

Phytosociological analysis of acidophytic alpine mat-grass swards in the Julian Alps and the Karawanks

Abstract Acidophytic alpine mat-grass swards are rare in the alpine belt of the predominantly calcareous Southeastern Alps of Slovenia, mostly occurring where limestone is admixed with marlstone or chert. Those for which we were able to make phytosociological relevés can be classified mainly into two syntaxa: Carici curvulae-Nardetum strictae vaccinietosum gaultherioidis and Sieversio-Nardetum strictae vaccinietosum. At slightly lower elevations, in the forest zone of the subalpine plateau Pokljuka, we found similar swards occupying small areas in frost hollows with luvisol on limestone. They include character species of various subalpine-alpine sward and snow bed communities and are classified into the syntaxon Homogyno alpinae-Nardetum scorzoneroidetosum croceae.

The Effects of Heat Advection on UK Weather and Climate Observations in the Vicinity of Small Urbanized Areas

Weather and climate networks traditionally follow rigorous siting guidelines, with individual stations located away from frost hollows, trees or urban areas. However, the diverse nature of the UK landscape suggests that the feasibility of siting stations that are truly representative of regional climate and free from distorting local effects is increasingly difficult. Whilst the urban heat island is a well-studied phenomenon and usually accounted for, the effect of warm urban air advected downwind is rarely considered, particularly at rural stations adjacent to urban areas. Until recently, urban heat advection (UHA) was viewed as an urban boundary-layer process through the formation of an urban plume that rises above the surface as it is advected. However, these dynamic UHA effects are shown to also have an impact on surface observations. Results show a significant difference in temperatures anomalies (p,< ,0.001) between observations taken downwind of urban and rural areas. For example, urban heat advection from small urbanized areas (sim 1,hbox {km}^{2}) under low cloud cover and wind speeds of 2–3,hbox {m},hbox {s}^{-1} is found to increase mean nocturnal air temperatures by 0.6,^{circ }hbox {C} at a horizontal distance of 0.5 km. Fundamentally, these UHA results highlight the importance of careful interpretation of long-term temperature data taken near small urban areas.

The role of plant functional traits in shrub distribution around alpine frost hollows

Introduction/Aims Functional traits aid understanding of species distribution and community composition along environmental gradients. However, studies that detail trait measurements along fine-scale environmental gradients are lacking for many vulnerable ecosystems. In this paper, we quantify how plant traits might explain the composition of shrubs in one such vulnerable system – frost hollows. Location Bogong High Plains, Victoria, Australia. Methods We measured species composition and a suite of traits (shrub height, stem specific density, leaf area and SLA, xylem vessel area and density, and leaf bud traits) for shrub species in three, 10 m × 10 m quadrats located across transition from hilltops down into frost hollows. We used ordinal regression to model vegetation transitions by relating the changes in shrub species occurrence along frost hollow gradients to each trait, and across multiple traits. We also assessed intraspecific trait variations along gradients. Results Several traits explained the position of species along a gradient of cold air accumulation (slopes leading into frost hollows). The most important traits were maximum shrub height, leaf area and xylem traits, which were clearly related to species location on the slopes in single trait models. More complex relationships were revealed with multi-trait models, which indicated that shorter species, those with smaller leaves and larger buds for their leaf size, and those with lower vessel density were more likely to be found toward the bottom of the slope. Within species, taller individuals and those with denser stems were also more common up-slope. Conclusion Our results suggest a shift in ecological strategies in frost hollows: the advantages of being taller and having large leaves may be diminished in these stressful environments. Shrubs that are shorter and have smaller leaves may also be better at avoiding the risk of frost damage. Our study shows how the fine-scale turnover of shrub species composition around frost hollows relates to plant functional traits, and captures the allocation trade-offs between coping with environmental stress and being competitive within these plant communities.

Frost hollows of the boreal forest: a spatiotemporal perspective

Summary Frost hollows (FH) are small, confined lichen‐dominated ecosystems surrounded by lichen woodlands. FH are impacted by repetitive frosts occurring during the growing season. We evaluated the dynamics of FH across the boreal forest in eastern Canada and assessed the influence of latitude as the main geoclimatic factor controlling their development. The distribution and abundance of FH along 39 longitudinal transects were based on aerial photographs and field validation. Black spruce (Picea mariana) in FH and adjacent woodlands were sampled for age determination, year of tree establishment, height growth rate of spruce, and intensity and frequency of frost rings. Most FH are located in the southern part of the boreal forest, in depressions bordered by dry, open, lichen woodlands. The inception and development of FH are not dependent on latitude but rather on the presence of lichen woodlands. Frost‐induced thúfurs and frost rings were more frequent and abundant in the southernmost FH, whereas the northernmost FH were devoid of thúfurs. Black spruce established synchronously in FH across the boreal forest, an indication of a climatic control associated with cloudier, humid conditions reducing radiative frost activity. Most FH spruce established after 1933 and peaked in the 1980s. Fewer frost events were recorded in the 1980s than in the 1990s. In the latter decade, frost events became more frequent, intense and synchronous across the boreal forest. Synthesis. The distribution of frost hollows (FH) is related to the presence of dry lichen woodlands that exacerbate frost activity during the growing season. Synchronous frost‐ring frequency across the biome also suggests that shared climatic conditions, in particular freezing temperature, humidity and cloudiness, are at the origin of the dynamics of FH. A longer growing season creates propitious conditions for a higher frequency of frost events and more intense soil cryoturbation. FH are climate‐sensitive ecosystems which can be used as proxies of the impact of global change on the boreal biome.

Characteristics of centipede (Chilopoda) assemblies in Dinaric frost hollows in Velika gora (Slovenia)

Current study is preliminary research of centipedes (Chilopoda) assemblies in Slovenian frost hollows. With two sampling methods in three series (June, August and November) in year 2010, 834 individuals were caught and indentified to 30 species. Most collected species had middle Europe distribution, 6 species were endemic for southeast Alps and northwest Balkan region, 3 of them are probably new for science. Five species had paleartic distribution. Maximum number of species found in one location was 28. Average density of centipedes was from 218 ind./m2 to 552 ind./m2. The alfa diversity of the centipede assemblies is medium compared to other locations in Dinaric part of Slovenia and evidently higher compare to other European forest. The same applies for average density and species richness. Overall centipede assemblies were more similar in one location during the season than to assemblies from different locations in the same month.

Occurrence of frost episodes and their dynamics in height gradient above the ground in the Jizerské hory Mts.

We have verified whether the temperatures in the zone of terminal leaders of saplings (+100 cm) were less extreme than the temperatures in the zone of terminal leaders of common-sized planting stock (+30 cm). In May and June of 2011 and 2012 we investigated the occurrence of late frosts at different levels above the ground. The number of days and amount of hourly frost records were counted and the sum of sub-zero temperatures was calculated. Our study confirmed that sub-zero temperatures mostly occur at levels near the ground. Therefore, on the sites exposed to late frosts, such as mountain frost hollows, in addition to common-sized planting stock we recommend to consider also the use of large-sized transplants (saplings), since their terminal buds are mostly above the zone near the ground most endangered by frost. &amp;nbsp;

Localities and Sites of Pulsatilla Vernalis in the Julian Alps

Localities and Sites ofPulsatilla Vernalisin the Julian AlpsApplying the standard Central-European method we phytosociologically studied the sites ofPulsatilla vernalis, a rare and protected species of Slovenian flora, in the frost hollows on mountain pastures Ovčarija and Za Grivo in the Fužina pasturelands (the Triglav mountains, the Julian Alps). We established that it grows in a unique community of swards and heaths which usually extends over small surfaces (4-10 m2) and is dominated by herbaceous perennial species (hemicryptophytes) and dwarf shrubs (chamaephytes) with mostly arcticalpine and south-European montane distribution. This community is explicitly (floristically and ecologically) different from the communities of swards and heaths described in the Julian Alps so far, so we classified it into a new associationPulsatillo vernalis-Dryadetum octopetalaeass. nova (orderRhododendro hirsuti-Ericetalia carneae) and subdivided it into two, floristically and ecologically clearly distinguished subassociations -ericetosum carneaesubass. nova and -vaccinietosumsubass. nova.

Minimalne temperature v slovenskih mraziščih v zimi 2006/07

Člani Slovenskega meteorološkega foruma, Oddelka za geografijo Univerze v Ljubljani in Gozdarskega inštituta Slovenije smo v letu 2004 pričeli z meritvami v slovenskih mraziščih. Mreža meritev se je v obdobju 2004-2006 razširila, z meritvami pa smo nadaljevali tudi v zimi 2006/2007. Meritve so potekale v več kot 30 mraziščih dinarskega, alpskega in tudi submediteranskega sveta. Kljub mili zimi 2006/2007, so temperature v mrazišču Hribarice padle pod -35°C.

Frost hollows of the boreal forest as extreme environments for black spruce tree growth

An extensive survey of spruce growth forms was conducted in frost hollows of the Parc national des Grands-Jardins located in the highlands of the Charlevoix region (Quebec). Frost hollows studied were situated within lichen woodlands, which are a favourable environment for the formation of cold air masses. The mean number of frosts recorded 1 m aboveground during the growing seasons of 1997–2002 indicates that there is no frost-free period in frost hollows. Based on the records of minimum temperature in two frost hollows, the critical threshold for frost-ring formation is a nocturnal temperature below 0 °C for 6.4 h with a climax at around –5.7 °C, i.e., at a cooling rate of 1.78 °C/h under the freezing point for at least 3.2 h. Frequent and severe nocturnal frosts slow down the colonization of black spruce in frost hollows, and are at the origin of the inverted tree line that surrounds frost hollows. Mean stem height of black spruce in frost hollows is 1.97 m ± 2.15. A comparative analysis of aerial photographs between 1950 and 1996 showed a 34% reduction in frost hollow area due to the progressive colonization of black spruce. Massive tree establishment occurred in frost hollows between 1970 and 1980 because of the reduced frequency of freezing temperatures during the growing season.

The relationship between winter minimum temperatures and spring phenology in a Southern Appalachian Cove

Winter minimum temperatures were recorded at four sites in Station Cove, a forested flat-bottomed ravine in the southern Appalachians of South Carolina, U.S.A. Unlike minimum temperatures found in frost hollows, cove minima were warmer than those found outside of the cove. Within the cove, minimum temperatures at study sites in the narrow, gorge-like western portion near a 20 m high cascade were warmer than those in the broader, eastern portion. Additionally, minimum temperatures near the ground were warmer than those at 1.4 m height above the surface. Selected spring-flowering plant species bloomed earlier in the western portion of the cove, while for the same plant species, within cove flowering dates were 2 to 3 weeks earlier than those outside of the cove. Station Cove, therefore, appears to harbor a microclimate that allows for much earlier flowering and leafing out of plant species in spring than does the surrounding region.

Thermal infrared survey of Aberdeen City: data processing, analysis and interpretation

Abstract The survey procedure and subsequent development of a microcomputer processing and analysis system adopted for a thermal survey of Aberdeen City is described. Thermal shadows on the imagery are shown to reflect air-mixing patterns at ground level and the sheltering effects of natural windbreaks, whereas canopy temperatures are related to vertical air-temperature profiles, thus enabling identification of frost hollows. Determination of heal loss from buildings was found to be problematical. The technique allows pollution sources and water-mixing patterns in river estuaries and nearshore zones to be identified.

Book Reviews

Abstract Abstract British Museum of Natural History Origin of Species New York: Cambridge University Press, 1981 120 pp. $19.95 hardcover, $8.95 paperback. Reviewed by Malcolm F. Farmer. World Book-Childcraft International, Inc. The Bug Book: The 1981 Childcraft Annual Chicago: World Book-Childcraft International, Inc., 1981 302 pp. $10.95. Reviewed by Walter L. Gojmerac. Frazier, Kendrick, ed. Paranormal Borderlands of Science Buffalo, N.Y.: Prometheus Books, 1981 469 pp. $12.95 paper. Reviewed by Barry Guinagh. Branley, Franklyn M. The Planets in Our Solar System New York: Thomas Y. Crowell, 1981 34 pp. $8.95 trade, $8.79 library. Reviewed by Frances B. Spuler. Butterfield, B. G., and B. A. Meylan Three-Dimensional Structure of Wood, 2d ed. New York: Chapman and Hall, 1981 103 pp. $39.95 hardcover. Reviewed by Herbert Grossman. Barman, Charles R., John J. Rusch, and Timothy M. Cooney Science and Societal Issues: A Guide for Science Teachers Ames: Iowa State University Press, 1981 151 pp. $7.95 paper. Reviewed by Robert W. Boenig. Pringle, Laurence What Shall We Do with the Land? Choices for America New York: T. Y. Crowell Junior Books, 1981 152 pp. $9.50 trade, $8.89 library. Reviewed by Waring B. Hill. Jerrard, H. G., and D. B. McNeill A Dictionary of Scientific Units, 4th ed. New York: Chapman and Hall, 1981 212 pp. $16.95. Reviewed by C. Bruce Hunter. Jones, C. W. Biological Energy Conservation, 2d ed. New York: Chapman and Hall, 1981 64 pp. $5.95 paper. Reviewed by Elmer F. Kohlmiller. Jacobs, S., and P. Cuatrecasas, eds. Membrane Receptors (Receptors and Recognition, Series B, Volume 11) New York: Chapman and Hall, 1981 240 pp. $48.00 hardcover. Reviewed by Donald F. Logsdon, Jr. Reif, Daniel K. Solar Retrofit: Adding Solar to Your Home Andover, Mass.: Brick House Publishing Co., 1981 199 pp. $8.95 paper. Reviewed by Arthur H. Doerr. Chapman, V. J., and D. J. Chapman Seaweeds and Their Uses, 3rd ed. New York: Chapman and Hall, 1981 334 pp. $49.95 hardcover. Reviewed by Robert W. Hoshaw. Bok, Bart J., and Priscilla F. Bok The Milky Way, 5th ed. Cambridge, Mass.: Harvard University Press, 1981 356 pp. $20. Reviewed by Van E. Neie. Busvine, J. R. Insects and Hygiene, 3d ed. New York: Chapman and Hall, 1980 568 pp. $55.00 hardcover. Reviewed by N. N. Raghuvir. Cobb, Vicki How to Really Fool Yourself New York: J. B. Lippincott, 1981 145 pp. $8.95 trade, $8.79 library, $4.95 paper. Reviewed by Frances Spuler. Bachelard, H. S. Brain Biochemistry, 2d ed. New York: Chapman and Hall, 1981 80 pp. $5.95 paper. Reviewed by Lloyd Wolfinbarger, Jr. World Book-Childcraft International, Inc. Science Year: The World Book Science Annual Chicago: World Book-Childcraft International, Inc., 1981 400 pp. $11.95–13.95 delivered (bindings vary). Reviewed by Gerald R. Rising. Ballentyne, D. W. G., and D. R. Lovett A Dictionary of Named Effects and Laws in Chemistry, Physics and Mathematics, 4th ed. New York: Chapman and Hall, 1981 346 pp. $20.00. Reviewed by Donald E. Myers. Pringle, Laurence Frost Hollows and Other Microclimates New York: William Morrow and Company, 1981 62 pp. $6.95. Reviewed by Ira W. Geer.

Ecological genetics and natural selection in mollusks.

Polymorphic snails of the genus Cepaea have been widely used for research in ecological genetics. Natural selection by selective predation is important in controlling morph frequencies in some populations of C. nemoralis in England. The importance of environmental selection in affecting other patterns of local genetic differentiation of population structure (area effects) is a matter of controversy. Some authors emphasize divergent evolution of whole gene pools between area effects, while others feel that climatic selection acting on individual loci is important. Analysis of 500,000 C. nemoralis snails from throughout Europe shows that there is a strong positive association between gene frequencies at the shell color locus and mean summer temperature, but that no climatic correlations are obvious at other loci. Another species, C. vindobonensis, which has a much simpler system of polymorphism than does C. nemoralis, was investigated in Yugoslavia, in a region where there is known to be intense microclimatic differentiation because of the accumulation of cold air in frost hollows. There was a striking tendency for snails with lightly pigmented shell bands to be found in places with a warm microclimate. Physiological and behavioral experiments demonstrate that this is due primarily to differential energy absorption from sunshine by the different shell phenotypes. As in C. nemoralis, other C. vindobonensis phenotypes show no detectable association with the environment. It is possible that genes whose frequencies cannot be related to environmental selection may have evolved strong linkage interactions with other genes in the population's gene pool. Selection by the ecological environment and the genetic environment may therefore both be important in controlling the genetic structure of snail populations.

Thermal infrared pictures and the mapping of microclimate.

Describes some field studies by the technique of air-borne infra-red line scanning (IRLS) in the Netherlands, with a theoretical introduction. The discussion covers the properties of 'warm' and 'cold' soils, the influence of vegetation cover, wind patterns, and the timing of flights. The studies include one on the location of frost hollows in sand-dune country SE of Barneveld, extensively afforested with Pinus sylvestris, where Pseudotsuga menziesii has suffered frost damage. [CF. FA 32, 6158]. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Enviornmental selection in the snail Cepaea vindobonensis in the Lika area of Yugoslavia.

Populations of the snail Cepaea nemoralis often show local genetic differentiations (area effects). The importance of environmental selection in controlling such patterns of gene distribution is uncertain, as some local associations of morph frequency with microclimate are not found in other populations. The eastern European snail C. vindobonensis has a very simple shell polymorphism. C. vindobonensis populations in north Yugoslavia show a clear tendency for snails with reduced band pigmentation to be found in places with a warm microclimate. This paper describes C. vindobonensis in another region with a similar topography. There is a very similar pattern of association of morph frequency with topography, snails with reduced band pigment being common only outside large basins which act as frost hollows. This consistency of association with environment suggests that climatic selection is of general importance in affecting morph frequency distribution in C. vindobonensis populations.

Ecological genetics and natural selection in molluscs.

Polymorphic snails of the genus Cepaea have been widely used for research in ecological genetics. Natural selection by selective predation is important in controlling morph frequencies in some populations of C. nemoralis in England. The importance of environmental selection in affecting other patterns of local genetic differentiation of population structure (area effects) is a matter of controversy. Some authors emphasize divergent evolution of whole gene pools between area effects, while others feel that climatic selection acting on individual loci is important. Analysis of 500,000 C. nemoralis snails from throughout Europe shows that there is a strong positive association between gene frequencies at the shell color locus and mean summer temperature, but that no climatic correlations are obvious at other loci. Another species, C. vindobonensis, which has a much simpler system of polymorphism than does C. nemoralis, was investigated in Yugoslavia, in a region where there is known to be intense microclimatic differentiation because of the accumulation of cold air in frost hollows. There was a striking tendency for snails with lightly pigmented shell bands to be found in places with a warm microclimate. Physiological and behavioral experiments demonstrate that this is due primarily to differential energy absorption from sunshine by the different shell phenotypes. As in C. nemoralis, other C. vindobonensis phenotypes show no detectable association with the environment. It is possible that genes whose frequencies cannot be related to environmental selection may have evolved strong linkage interactions with other genes in the population's gene pool. Selection by the ecological environment and the genetic environment may therefore both be important in controlling the genetic structure of snail populations.