Showing papers by "Swiss Federal Institute for Forest, Snow and Landscape Research published in 1992"

Fennoscandian summers from ad 500: temperature changes on short and long timescales

Abstract: Quantitative estimates of 1480 years of summer temperatures in northern Fennoscandia have previously been derived from continuous treering records from northern Sweden. Here we show the results of spectral analyses of these data. Only a few peaks in the spectra are consistently significant when the data are analyzed over a number of sub-periods. Relatively timestable peaks are apparent at periods of 2.1, 2.5, 3.1, 3.6, 4.8, ∼ 32–33 and for a range between ∼ 55–100 years. These results offer no strong evidence for solar-related forcing of summer temperatures in these regions. Our previously published reconstruction was limited in its ability to represent long-timescale temperature change because of the method used to standardize the original tree-ring data. Here we employ an alternative standardization technique which enables us to capture temperature change on longer timescales. Considerable variance is now reconstructed on timescales of several centuries. In comparison with modern normals (1951–70) generally extended periods when cool conditions prevailed, prior to the start of the instrumental record, include 500–700, 790–870, 1110–1150, 1190–1360, 1570–1750 (A.D.) with the most significant cold troughs centred on about 660, 800, 1140, 1580–1620 and 1640. Predominantly warm conditions occurred in 720–790, 870–1110 and 1360–1570 with peaks of warmth around 750, 930, 990, 1060, 1090, 1160, 1410, 1430, 1760 and 1820.

Genetic variation within European tree species

Abstract: This paper reviews results of studies on genetic variation in various European coniferous and angiosperm tree species, with emphasis on Picea abies and Pinus sylvestris, Abies alba, Fagus sylvatica, and Castanea sativa. Most of the studies employ enzyme gene markers, but terpenes and other markers are also used. The comparison of data is complicated due to the variety of measures of genetic variation that are reported. Nevertheless, substantial differences in intra- and interpopulational genetic variation can be observed among and also within species. Causes for such heterogeneity are briefly discussed. The necessity for monitoring genetic variation and for standardizing measurement of genetic variation is emphasized.

Seasonal growth, δ13C in leaves and stem, and phloem structure of birch (Betula pendula) under low ozone concentrations

Abstract: The growth of potted birch cuttings (one clone of Betula pendula) was studied under low O3 concentrations (0, 0.050, 0.075, 0.100 μl l-1) throughout an entire growing season. With increasing O3 dose, 20–50% of all leaves formed were prematurely shed, while 40–70% of the remaining foliage displayed advanced discoloration by the end of the season. Ozonation affected the S, P and N concentration of leaves and increased δ13C in leaves and stem, while the CO2 assimilation rate declined with increasing CO2 concentration in mesophyll intercellulars. While whole-plant production correlated negatively with the O3 dose, ozone increased the specific leaf weight (i.e. leaf weight/leaf area, SLW) but decreased the ratios of stem weight/stem length and root/shoot biomass. Neither the latter ratio nor SLW changed in experimentally defoliated control plants, whereas in ozonated plants starch accumulated along leaf veins and phloem tissue was deformed in the leaf petioles and the stem. Only in early summer was the relative growth rate higher in the ozonated than in the control plants. The ratio of whole-plant biomass production versus total foliage area formed was lowered under O3 stress. However, when relating biomass to the actual foliage area present due to leaf loss, this ratio did not differ between treatments. Similarly the ratio of actual foliage area versus basal stem area in cross-section did not differ. Overall, whole-plant production was strongly determined by O3-caused changes in crown structure and began to be limited at O3 doses (approximately 180 μl l-1 h) similar to those of rural sites in Central Europe.

Sources of variation in rapidly inducible responses to leaf damage in the mountain birch-insect herbivore system.

Abstract: Studies on rapidly inducible resistance in trees against insect herbivores show substantial variation in the strength of responses. Here we report the results of a study which examined causes of this variation. We bioassayed the quality of leaves of two developmental phases (young vs. mature) of the mountain birch Betula pubescens ssp. tortuosa by measuring the growth of two instars of Epirrita autumnata larvae. We used only short shoot leaves from trees of a natural stand, uniform in size and age. Damage was caused by larvae and artificial tearing of leaf lamina, varying the scale and time. We separated seasonal changes in plants from instar-dependent effects of the animals by testing experimental larvae in two subsequent growth trials. We found that only larval-made damage induced responses in leaves that made the leaves significantly poorer quality for the test larvae. Artificial damage induced only weak responses, and artificial canopy-wide damage even caused slight improvement of leaf quality. Cumulative leaf damage did not strengthen birch responses. Leaves that were in the expansion phase responded to damage while fully-expanded, mature leaves showed no response. The pattern of responses indicated that there might be physiological constraints: small-scale damage induced resistance against the larvae but largescale damage did not. Prevalent weather conditions might have modified these responses. Larvae of two instars and sexes, of low- and high-density populations responded to leaf damage similarly. However, prior experience of larvae with the host plant may have affected subsequent larval performance. Variation in rapidly inducible responses in birches was caused by plant characters rather than by test animals.

Ontogeny of synthesized Picea abies (L.) Karst.–Hebeloma crustuliniforme (Bull. ex St Amans) Quél. ectomycorrhizas

Abstract: summary Ectomycorrhizas were synthesized between Picea abies (L.) Karst. and Hebeloma crustuliniforme (Bull. ex St Amans) Quel. in growth pouches containing activated charcoal filter paper. Immediately emanating hyphae from inoculated plugs contacted root hairs and root surfaces, hyphal morphology was altered. They became short-celled with few clamp connections, highly branched, and lacked cell wall ornamentation. Then, hyphae on root surfaces formed an inner synenchymatous mantle and loose hyphae formed an outer prosenchymatous mantle. Simultaneously, root cap cells became invaded by fungal hyphae and their remnants were incorporated into the inner mantle. Further root elongation took place but root hair production was suppressed. Thirdly, a Hartig net began to form in basal portions of developing ectomycorrhizas and the fungal mantle became denser and thicker. Fourthly, growth of the root was reduced and the hyphae of the Hartig net penetrated between cortical cells moving toward the apex. Fifthly, metacutis occasionally surrounded the meristem. At this stage the formation of the ectomycorrhiza can be considered to be complete and the rootlet itself is temporarily in a dormant state.

Longevity and senescence of needles in Pinus cembra L.

Abstract: Needle development has been investigated in Pinus cembra at several locations in the Grisons Special attention has been paid to longevity and senescence Despite large variations from one tree to another, longevity (up to 12 years) appeared to increase with increasing altitude With increasing age, contents of nutrients such as N, P, K and, to a lesser extent, Mg and S tend to decrease Photosynthetic activity did not decline with increasing age of short shoots Senescence begins in mid-August in needles of the oldest age classes It is associated with the mobilization and withdrawal of large proportions of N, P, K and also Mg and S, but Ca appears to be immobile The extent of yellowing is irregular in individual trees but needle losses on a large scale are followed by reduced losses in subsequent years

Ectomycorrhizal syntheses with Picea abies and three fungal species: a case study on the use of an in vitro technique to identify naturally occurring ectomycorrhizae

Abstract: Ectomycorrhizal syntheses between Picea abies and the fungal associates Scleroderma citrinum, Boletus luridus, and Tricholoma vaccinum were carried out using Melin's Erlenmeyer flask technique. The symbioses of S. citrinum were characterized by a mantle composed of an outer prosenchymatous and an inner synenchymatous layer. The mantles of B. luridus and T. vaccinum were solely prosenchymatous. Rhizomorphs were produced in all treatments, but only in association with S. citrinum were they differentiated with additional, enlarged hyphae. All synthesized ectomycorrhizae were white or whitish to light orange and greyishorange. On large-scale root sampling in two differing Picea abies forests in Switzerland, nine out of a total of 22 morphological types of ectomycorrhizae were white or yellow in colour and were, therefore, comparable with the synthesized ectomycorrhizae. These nine natural types generally had distinct mantle features (irregular synenchyma, gelatinous matrix, cystides, thick-walled hyphae), but mostly lacked clamp connections. Synthesized ectomycorrhizae, on the other hand, lacked distinct mantle characteristics and always had clamp connections. Natural and synthesized white or yellow ectomycorrhizae did not coincide morphologically and thus identification of the fungal partners of natural symbioses by means of in vitro-synthesis with potential ectomycorrhizal fungi was not possible in the present study.

On the taxonomy of five saxicolous species of the genus Rinodina (lichenized Ascomycetes)

Abstract: The taxonomy, ecology and distribution of Rinodina deflectens, R. interjecta, R. rinodinoides, R. tephraspis and R. trachytica are treated. New combinations are made for R. interjecta and R. rinodinoides. R. melanocarpa and R. serpentini are synonyms of R. rinodinoides. R. badiella and R. kentuckyensis are synonyms of R. tephraspis, and R. iberica of R. trachytica.

Growth rates in diameter, basal area, and height of Pilgerodendron uviferum; relationship between growth index and germination

Abstract: Increment borer samples taken at breast height in Pilgerodendron uviferum (Cupressaceae) trees growing in two Chilean forest stands near latitude 42° south were used to study growth rates in diameter, basal area, and height. Radial average growth is 0.51 mm/year in Santa Lucia 0.44 mm/year in the Piuchue stand; the correlation between diameter and age is 0.79 in Santa Lucia and 0.64 in Piuchue. Similar results were obtained in the basal area/age relationship. Both groups of trees have a low rate of growth compared to rates obtained in other studies. Maximum values for radial growth (culmination age) are reached at 110 years of age in Santa Lucia and 50 years in Piuchue. Growth in height, averaging 5.8 cm/year, appears to be similar in all trees analyzed; occasional differences can be attributed to understory position of some trees. Comparison of radial growth and germination of Pilgerodendron plants shows a synchronous relationship, suggesting an influence of climate on the pattern of forest regeneration.

The Swiss National Research Program “Forest Damage and Air-Pollution” (NFP 14+)

Abstract: The objective of this paper is to present a review of the NFP 14 + . The studies of this multidisciplinary research program were carried out between 1985 and 1989. They were concentrated on three forest sites at different altitudes, one in the densely populated Mittel-land, one in a protection forest in the Prealps, and one in the Alps proper. All sites are dominated by Norway spruce (Picea abies). The main goal of the case studies was a comprehensive characterization of the sites, giving the opportunity to evaluate the role of air pollution in forest health. The program included various ecological investigations as well as measurements of meteorological parameters, gaseous pollutants and atmospheric deposition. The results indicate neither a temporal nor a spatial dependence of crown defoliation on air pollution for the study sites. Nevertheless, there is experimental evidence that the present-day ozone levels in Switzerland have to be considered as a risk factor for more sensitive tree species.