Oak woods are the most important forest types growing on 570,700 hectares in Hungary that is about 32% of total forested lands. This paper reports results about the regeneration succession on clearings of sessile oak-Turkey oak forests, following successive clear-cut harvesting practice. Phytosociological relevés were taken, according to the space for time substitution model, covering stand ages from 2 to 28 years old. Major steps of the forest regeneration were analysed by multivariate methods and four stages were determined: I = 1–3 years, II = 4–11, III = 12–21(–25) and IV = (22–)26–28 years. Light climate of the four stages were characterised by measuring relative irradiation under clear sky conditions (RI) at four elevations (0, 20, 40 and 80 cm above ground). Herb layer phytomass was studied by the harvesting method in the same stands where RI was determined.Considering statistically significant differences in the studied variables among stages, two main stress periods were distinguished. The most drastic stress event appears during the transition from the mature forest stage to stage I. It is associated with a great and sudden increase in RI at the herb layer level (at 80 cm above ground RI was 95.5%). Also the amount of total herb layer phytomass of stage I increases considerably reaching more than three times higher values than that found under cutting age mature stands.The second stress period occurs in stage III. Significant decline of light intensity occurs during the transition from stage II to III, resulting an RI of 2–2.5%. Herb layer phytomass also becomes significantly reduced in this stage, amounting only 4 g DW/sqm. During this rather unfavourable period the majority of typical sessile oak-Turkey oak species disappear from the stands. A strong correlation between log(RI) and the herb layer aboveground phytomass was also established.The described two stress phases may lead to forest degradation, since the species able to survive the first stress phase with high RI probably cannot tolerate the very low illumination level in stage III. To prevent losses from the flora and vegetation, or at least to mitigate the damage, more frequent thinning in the thin pole phase (stage III) is recommended. Another solution would be the cultivation of uneven-aged forests, with selection cutting or single-tree selection.
G. Brundu, J. Brock, I. Camarda, L. Child and M. Wade (eds.), 2001. Plant invasions: Species Ecology and Ecosystem Management. 338 pages with 127 figures and 80 tables. Backhuys Publishers, Leiden. ISBN 90-5782-080-3. Paperback; price: EUR 93.00/USD 89.00 D.J. Levey, W.R. Silva and M. Galetti (eds.), 2002. Seed Dispersal and Frugivory: Ecology, Evolution and Conservation. xvi + 511 pp. CABI Publishing, Wallingford, UK. ISBN 0 85199 525 X (hardback). Price: GBP 75.00 / USD 140.00
Definitions of seed banks are discussed in the introductory part of the paper. In the second part, a literature review regarding sampling problems in soil seed bank ecology is presented. Regarding sampling depth, a rapid decline in soil seed content is demonstrated from example studies. The use of soil cores with 5 cm or 10 cm depth is suggested to ensure comparability of results. For determination of optimal sample volumes for various communities, the species saturation model is suggested such that “minimal volume” can be defined for soil seed banks in the same way that “minimal area” can be defined in phytosociological studies. Although sampling time may depend on research goals for vegetation types with a winter standstill period, late autumn sampling is suggested for detecting the entire soil seed bank, whilst late spring sampling is recommended for the examination of its persistent part. Studies looking at medium (plant community level) and fine scales (patch level) have demonstrated that soil seed bank distributions show horizontal aggregation for most of the cases and for most of the species. Seed dispersal processes which are among major factors responsible for such aggregated patterns are also discussed.
Belgrano, A., U.M. Scharler, J. Dunne, and R.E. Ulanowicz (eds.), 2005. Aquatic Food Webs - An Ecosystem Approach. Oxford University Press, Oxford, x+262 pp. ISBN 0-19-856483-X, paperback, price: GBP 39.95, USD 65.00.; Fenner, M. and K. Thompson. 2005. The ecology of seeds. Cambridge University Press, Cambridge, x+250 pp (with 47 figures and 2 tables). ISBN 0-521-65311-8, hardback, price: GBP 55.00, USD 90.00; ISBN 0-521-65368-1, paperback, price: GBP 26.00, USD 45.00.;
Ward, J. V. and U. Uehlinger (eds.) 2003. Ecology of a Glacial Flood Plain. Kluwer Academic Publishers, Dordrecht, xvii+320 pp. ISBN: 1-4020-1792-8, hard cover, price: EUR 90, USD 99, GBP 62.; Heil, G. W., R. Bobbink and N. T. Boix (eds.) 2003. Ecology and Man in Mexico's Central Volcanoes Area. Kluwer Academic Publishers, Dodrecht, ix+222 pp. ISBN 1-4020-1708-1, hard cover, price: EUR 130, USD 143, GBP 89.5.;
The paper evaluates spatial autocorrelation structure in grassland vegetation at the community level. We address the following main issues: 1) How quadrat size affects the measurement of spatial autocorrelation for presence/ absence and cover data? 2) What is the relationship between spatial autocorrelation and classification? 3) Is there a temporal change of spatial autocorrelation in the vegetation studied? We found that multivariate variogram shape, variance explained and the sill are different for presence/absence data and cover data, whereas quadrat size increases apparently introduce a stabilizing effect for both. Spatial stationarity is detected for species presence, and non-stationarity for cover. A new graphical tool, the clusterogram is introduced to examine spatial dependence of classification at various numbers of clusters. We found that spatial autocorrelation plays a crucial role in the classification of vegetation and therefore we suggest that its effect should not be removed from clustering. Mutual interpretation of variogram and clusterogram shape may be informative on the number of meaningful clusters present in the data. Spatial autocorrelation structure did not change markedly after 23 years for presence/absence data, indicating that the vegetation of the study area is stationary in time as well. The present study demonstrates that traditional quadrat data are suitable for evaluating spatial autocorrelation, even though field coordinates are recorded several years after sampling is completed.
Aquatic hyphomycetes or Ingoldian fungi are the major decomposers of leaf litter in temperate aquatic ecosystems. Role of leaf litter quality in structuring hyphomycete communities is intensively discussed among hydrobiologists. Therefore, an adequate sampling strategy of the leaf litter is essential in this field. The present paper aims analysing the appropriate sample size of leaf litter with various diversity and evenness combinations taken from streambeds in the temperate deciduous forest zone.Leaf litter in the streambed was sampled at four stream sections of two tributaries of the Morgó stream in the Börzsöny Mts, Hungary. The tributaries differed in water chemistry, altitude and riparian vegetation. To analyse species number-sample size relations, species saturation diagrams were drawn and statistically evaluated.Results showed that: (1) a sample size of 500 leaves sufficiently describes the species composition of leaf litter taken from streambeds in the temperate forest zone, in cases of low diversity forest stands and high diversity forest stands coupled with high evenness; and (2) for forest sites with high diversity coupled with low evenness values a litter sample composed by 800-1000 leaves is advised to investigate to achieve satisfactory estimation of the species composition of leaf litter.The sampling methods described in this paper are proposed for studies where estimation of leaf litter composition is required to understand the available substrate quality for litter decomposing organisms.