Proceedings of the Estonian Academy of Sciences

CONTENTS & ABSTRACTS

In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Biology. Ecology

Volume 53 No. 1 March 2004

Estimation of leaf area index in a willow plantation; 3–13

Ebe Merilo, Katrin Heinsoo, and Andres Koppel

Abstract. The leaf area index (LAI) was estimated using different methods in four plots of a willow plantation representing two species (Salix dasyclados Wimm. and Salix viminalis L.) and two nutrition levels in 1995–97. Allometric relations between the shoot diameter and leaf mass or litter collection were used for direct estimation of LAI. Allometric LAI values in the studied plots varied from 1.0 to 16.6. Fertilized plots displayed higher LAI values compared with the corresponding control plots. LAI obtained from litter collection was higher than allometric LAI for the control plots, but considerably lower than allometric LAI for the fertilized plot of S. dasyclados. When an indirect method (hemispherical “fish-eye” photographs) was used, LAI was strongly underestimated for the fertilized plots and slightly overestimated for the control plots. It is concluded that the allometric method yielded the most accurate LAI estimates.

Key words: allometric relations, clumping index, “fish-eye” photography, LAI, litter collection, Salix, specific leaf area.

Tropane alkaloid production and riboflavin excretion by Hyoscyamus niger L. hairy root cultures; 14–24

Rael Vardja, Katrin Pudersell, Tõnis Vardja, Ain Raal, and Elmar Arak

Abstract. The production of tropane alkaloids and excretion of riboflavin was comparatively investigated in hairy root clones of Hyoscyamus niger transformed with Agrobacterium rhizogenes strain LBA 9402 and wild-type (WT) root culture of H. niger. From six selected hairy root clones, one clone (C-1) was relatively similar to WT roots in morphological features and growth intensity. The other, fast-growing (FG) root clones grew twice better than WT roots and had very variable morphological features. Clone C-1 produced, depending on the medium (MS, B5, Knop-M), 5 to 15 times more scopolamine and 1.5 to 2 times more hyoscyamine than WT roots. Most of the FG root clones produced less tropane alkaloids than WT roots, but there was a strong dependence on the composition of media. The excretion of riboflavin from C-1 clone was somewhat lower than that from the WT roots. The excretion of riboflavin from the FG root clones occurred at a detection level, but increased under iron deficiency of media.

Key words: Hyoscyamus niger, wild-type roots, hairy roots, tropane alkaloids, riboflavin.

In situ and satellite investigations of optical properties of the ice cover in the Baltic Sea region; 25–36

Helgi Arst and Liis Sipelgas

Abstract. Possibilities of describing the spatial variation and properties of the ice cover in water bodies by simultaneous in situ and satellite measurements were studied. In 2000–03 a field programme on the structure and optics of ice and snow was performed in six Estonian and three Finnish lakes and in coastal waters of the Baltic Sea. Additionally properties and development of the ice cover in the Baltic Sea during winter 2002/03 were estimated relying on the data of the Moderate Resolution Imaging Spectroradiometer (MODIS), installed on the satellites Terra and Aqua. The surface albedo of the water bodies varied from about 95% for fresh snow to 19–22% for slush or the thin water layer on the ice. The vertically averaged diffuse attenuation coefficient of ice for brackish water Santala Bay exceeded considerably that for lakes. It was demonstrated that MODIS images give rather detailed information on ice conditions, which makes it possible to distinguish snow covered fast ice from new and melting ice, and also to detect the relative changes of surface albedo.

Key words: wintertime water bodies, optical properties of ice cover, albedo, remote sensing of ice.

Application of diatom indices in the evaluation of the water quality in Estonian streams; 37–51

Sirje Vilbaste

Abstract. Diatom indices, based on the relative abundance of epilithic diatom species, were calculated for 139 river reaches from 21 watercourses using the software OMNIDIA. The applicability of 16 indices used in different European countries as indicators of the ecological status of running water was tested. Trophic degree (oligo-, meso-, eu-, hypertrophic) and water quality class (high, good, moderate, poor, bad) were used in the analysis. Nine of the studied 16 indices (Biological Diatom Index, Descy’s Index, Descy & Coste Diatom Index, Leclercq & Maquet Index, Schiefele
& Schreiner Index, Sládeček’s Index, Specific Pollution Sensitivity Index, Trophic Diatom Index, Watanabe’s Index) were considered as promising in Estonia and selected for further investigation.

Key words: diatom indices, Estonia, European Union, OMNIDIA software, periphyton, running waters, water quality.

Breeding bird communities in two Estonian forest landscapes: are managed areas lost for biodiversity conservation?; 52–67

Asko Lõhmus

Abstract. To establish new reserves for biodiversity, the conservation value of currently managed forests should be assessed. I compared the bird fauna of a large reserve (Alam-Pedja) and an adjacent managed forest landscape in east-central Estonia. At 20-ha scale, managed forests had a denser and more species-rich bird fauna and as high abundance of species of conservation concern as the reserve. This was due to the higher small-scale diversity of vegetation types and a higher share of fresh-type forests in the managed area, since at the landscape scale, the species richness of the managed forest and the reserve were similar. Moreover, the species–area curves of the reserve and a combined sample of the reserve and the managed landscape did not differ, indicating that the latter added new species only due to enlarged area and not because of a distinct fauna. Thinnings changed community composition and tended to decrease species-richness. I conclude that managed forest landscapes are impoverished but still valuable for the conservation of forest birds in Estonia. Using the existing middle-aged or old unmanaged second-growth for new reserves seems to be an acceptable conservation strategy if the potential sites of conservation are immediately excluded from commercial use.

Key words: forest birds, line transect counts, managed forest, reserve, thinning.

Instructions to authors; 68–70