Gegenwärtige Hauptprobleme der landwirtschaftlichen Schädlingsforschung in Finnland

Zusammenfassung Einige der wichtigsten gegenwärtigen Probleme hinsichtlich der landwirtschaftlichen Schädlinge in Finnland sind folgende:Bei Getreide die Schäden durchCalligypona pellucida am Hafer sowie die Schäden durch die Fritfliege(Oscinella frit) an Saat von Winter- und Sommergetreide, die durch Blasenfüßer(Thysanoptera) u. a. Arten verursachte Weißährigkeit und Schmachtkörnigkeit, deren Bekämpfung noch nicht befriedigend entschieden ist. — Beim RotkleePhytonomus nigrirostris, Apion apricans undA. assimile, Sitona spp. undDitylenchus dipsaci, deren Biologie und Bekämpfung weiterhin fortgesetzt werden, — Bei ÖlpflanzenCeuthorrhynchus assimilis undC. quadridens sowieDasyneura brassicae, deren Bekä mpfung zu ermitteln ist. — Bei Zuckerrübe sowie einigen anderen Kulturpflanzen Bedeutung und Bekä mpfung vonLygus-Arten (besondersL. rugulipennis undL. pratensis). Bekämpfung der Rübenfliege(Pegomyia hyoscyami) bei Zuckerrübenkulturen. — Bei den Wurzelschädlingen von Gemüse und Hackfrüchten Klären von Biologie und Bekämpfung der Kohlfliegen (Hylemyia brassicae undH. floralis), der Fliegenschädlinge von Zwiebeln (Hylemyia antiqua, Eumerus tuberculatus undE. strigatus) und der Möhrenfliege. — Die Wirkung der Spritzungen in Obstgärten auf die wichtigsten Schä dlinge(Metatetranychus pilosus, Doralina pomi, Psylla mali, Carpocapsa pomonella, Argyresthia conjugella) und ihre wirksamsten Feinde.— In Beerengärten bei den ArtenTarsonemus fragariae, Eriophyes ribis undPachynematus pumilio sowie in Obstgärten bei der ArtAnisandrus dispar Intensivierung der Bekä mpfung. — Älchen(Anguillulidae), besondersdas Kleeälchen und Klärung von Lebensbedingungen und Bekämpfung desKartoffelälchens. — Bedeutung und Bekämpfung der Wühlmäuse (besondersMicrotus agrestis, M. arvalis undArvicola terrestris). — Untersuchung der Bedeutung von virusverbreitenden Insektenarten. — Erforschung der Nachteile von Bekämpfungsmitteln für die Pflanzen.     

City Branding as a Response to Global Intercity Competition

Globalisation is dramatically changing the context of urban communities and the premises for urban development policy. In the context of global intercity competition, cities' major goal is to increase their competitiveness, in which the positioning and attractiveness of a city have a critical function. Attraction‐oriented development strategies aim at effective absorption of external resources from the global space of flows. At the core of attraction strategy are business promotion activities with appealing incentives, but it is assumed that such a competition is risky and may lead to a race to the bottom. Therefore the emphasis is increasingly on less costly and more synergistic city marketing, which utilises city branding and “city profiling” that aim at attract high value‐adding services or high‐tech firms. This paper proposes a city attraction hypothesis that states that global intercity competition is essentially about a city's ability to attract the highest possible value from global flows of values in order to promote urban development. The result of such a global intercity competition determines cities' functions and positions in the global division of labour and thus in the global urban hierarchy, and ultimately determines their ability to increase prosperity and welfare in urban communities.     

Communities of Enchytraeidae (Oligochaeta) in planted birch stands as compared with natural forests in central Finland

This study compares the enchytraeid communities in anthropogenous birch (Betula pendula) stands of different origin with each other and with natural forests at the same latitude in Finland. Nine sites were investigated: three birch stands planted ca. 30 years prior to the study after clear-cutting of spruce stands, three birch stands established ca. 30 years earlier on arable soil (cleared from earlier coniferous forest), and three natural deciduous forests. Each site was sampled three times (May, August and October) in 1999, animals were extracted using the wet funnel method, counted and identified. Non-metric multidimensional scaling (NMS) was used to analyse the communities. There were clear differences between the birch stands established after spruce forest and after cultivation, and between these and natural deciduous stands, but even more between replicates of similarly managed forests. Total numbers and populations of most species were lower in birch-after-field than in birch-after-spruce. The superdominant species in coniferous forests, Cognettia sphagnetorum, was dominant in all birch-after-spruce sites and one natural deciduous site. Enchytronia parva was the only species more abundant in birch-after-field than in birch-after-spruce. It is hypothesized that, in addition to soil acidity, accidental transport by man explains the presence of many species on a given locality, and that competition with earthworms plays a role in regulating enchytraeid abundances.     

Dispersal of microarthropods in forest soil

This experiment was a part of a research on the soil community in anthropogenous birch stands in Finland. In that study it was found that communities of Collembola are similar in birch stands of different origin (cultivated field or spruce forest), while the communities of Oribatida are essentially different. When compared to original spruce forest, the communities of both groups are different.Cultivation eliminates the populations of most microarthropod species, that have to disperse after reforestation from the surrounding areas. The aim of the experiment was to study the ambulatory dispersal of soil microarthropods. It was carried out in plastic boxes filled with an intact block of defaunated surface soil taken from a birch stand that was established ca. 30 years earlier on a cultivated field. A strip of intact spruce forest soil was placed at one end of the boxes to harbour the source populations. At the opposite end we placed a row of pitfall traps. Soil samples were taken every two weeks at increasing distances from the source soil using a metal corer, and animals were extracted in a high gradient apparatus. The pitfalls were also emptied every two weeks. The experiment lasted for ten weeks.Pitfall and soil sample data gave an estimation of the maximum dispersal rate for each species or genus. The distance that the populations could potentially disperse in 30 years (age of the stand) indicated that some, but not all of the species could have actively migrated to the central parts of the birch stand (30 m).     

The role of soil fauna in ecosystems: A historical review

The research development in this review is divided into successive periods: (1) “From Darwin to Satchell”, covering the “pre-experimental” decades dealing with the functions of earthworms, (2) “Litterbag Studies”, characterized by field experiments on the faunal influence on litter decomposition, (3) “The Time of IBP”, concentrating on community energetics, (4) “The Microcosm Era”, laboratory studies that started with simple systems, followed by increasing complexity of experimental setup and community of organisms, including living plants, and ending to laboratory-scale “ecosystems”, (5) the recent “Biodiversity Boom”, analysing the relations between soil biodiversity and ecosystem functions, and (6) the current “Holistic View” that tends to link the diversity and functions of aboveground and belowground communities. These “periods” started roughly in this order, but are largely overlapping, since the early techniques are in continuing use together with the modern ones. The current knowledge on the role of soil biota, their diversity and various components has accumulated mainly during the last 30 years, resulting in the modern view of soil fauna as a part of the ecosystem.     

Effects of seed origin and sowing time on timing of height growth cessation of Betula pendula seedlings

We studied the effects of seed origin and sowing time on height development and timing of height growth cessation of first-year silver birch (Betula pendula Roth) seedlings in a greenhouse experiment. Seeds of seven origins ranging in latitudes from 58 degrees to 67 degrees N were sown at 1-2-week intervals eight times from May 21 to July 30, 2001. The day/night temperature in the greenhouse was set at 20/10 degrees C, but lighting was natural and day length varied accordingly. Seedling height was measured twice a week. The interaction term between seed origin and sowing date was significant, but the pattern of height development and timing of growth cessation depended systematically on latitude of seed origin and sowing date. As seed origin became increasingly northern, growth cessation began earlier and resulted in shorter growth periods. Later sowing dates delayed growth cessation but also shortened the growth period. Final seedling height systematically decreased with increasingly northern origins and with later sowings. Linear regression analysis predicted timing of growth cessation, night length at growth cessation, length of growth period and final seedling height with high precision when the latitude of seed origin and sowing time were predictor variables. The timing of height growth cessation was determined by the seed origin, night length and developmental stage of the seedlings.     

Breeding plans in case of global warming

Summary Many cultivated crop plants of temperate and cool temperate zones have during their domestication been transferred far from their original habitats and been distributed over a wide range of climates. In general crop plants seem to possess potential to climatic adaptation. Processes in the past have taken hundreds or thousands of years and over large number of generations. The concern on the velocity of the expected global warming and of subsequent changes in other factors justifies planning of breeding for global warming. Perennial plants, forest trees in particular are more at the focal point than annual plants. Most agricultural annuals may be replaced any year with another cultivar or species better adapted to contemporary circumstances. Trees need tens of years to reach commercial dimensions or fructiferous age.Capriciousness is the main problem of climate change. Large variation of temperature, precipitation among years actually masks the gradual change of average values. The amplitude of variation among years exceeds the predicted average change. Thus, plasticity of individuals besides within population variation in adaptive traits is a corner stone of breeding plans. From the ecological point of view two factors are significant: 1. mild winters may interfere dormancy release and frost tolerance, and also alter host-parasite relationships. 2. The timing of thermal seasons will change in relation to photoperiod. This phenomenon is most prominent in the far north, where the relative warming is largest and the photoperiodic pattern steepest. Even though perennial plants display potential of acclimatization, selection and breeding are eligible measures to improve productivity. As long as the magnitude and velocity of the global warming remain uncertain, it is impossible to set specified aims to breeding. The only reasonable method is to run parallelly several lines with differing patterns of adaptive traits. Multiple population breeding system (MPBS) seems to be tailored to this purpose.     

Responses of co-occurring populations of Dendrobaena octaedra (Lumbricidae) and Cognettia sphagnetorum (Enchytraeidae) to soil pH, moisture and resource addition

Dendrobaena octaedra (Lumbricidae) and Cognettia sphagnetorum (Enchytraeidae) are the two most dominating soil invertebrates in terms of biomass in boreal coniferous forest soils. A microcosm experiment was set up in order to study the influence of pH, moisture and resource addition on D. octaedra and C. sphagnetorum when both species are simultaneously present. Two kinds of coniferous forest humus were used as substrate, pine stand humus (pH 4.2), and spruce stand humus (pH 4.6); in the third treatment the pine stand humus was adjusted with slaked lime (CaOH₂) to the same initial pH as the spruce stand humus. Each substrate was adjusted to water contents of 25%, 42.5% and 60% of WHC (referred to as ‘dry’, ‘moist’ and ‘wet’). In the second part of the experiment, spruce needle litter and birch leaf litter were separately added into the pine stand humus (‘moist’, unlimed) and compared with a control without litter. The microcosms were plastic jars with 75 g (d.m.) of humus, into which 4 specimens of D. octaedra and 70 specimens of C. sphagnetorum were added. D. octaedra showed the highest biomass and C. sphagnetorum the lowest biomass in the spruce stand humus with higher pH. Moisture did not affect earthworms, while C. sphagnetorum thrived best at the highest moisture. Addition of both kinds of litter increased the numbers and biomass of D. octaedra, while on C. sphagnetorum resource addition had little effect. The results help to explain the abundance of these two species in coniferous forests differing in soil acidity, moisture and fertility.     

Pressurized hot water extraction of Norway spruce hemicelluloses using a flow-through system

Norway spruce saw meal was extracted with pressurized hot water at 120–240°C using a flow-through system. Only small amounts of hemicelluloses were extracted at 120–160°C, but dissolution was significantly enhanced when higher extraction temperatures were applied. All hemicelluloses but only 15% of lignin were removed from wood at 220°C, and even less lignin was extracted at lower temperatures. Partial degradation of cellulose seemed to take place only at 240°C. Of the total amount of extracted hemicelluloses, 4–22% was hydrolyzed to monosaccharides. Although the average molar masses of extracted hemicelluloses decreased with increasing extraction temperature, even at 240°C the extracted carbohydrates occurred, on average, as polysaccharides. Polysaccharides with an average molar mass of 31 kDa were obtained at 170°C. The molecular-mass characteristics and yield of carbohydrates depend on the extraction temperature, which should be chosen based on the end use of the isolated hemicelluloses.     

Polyphenol oxidase, tannase and proteolytic activity in relation to tannin concentration in the soil organic horizon under silver birch and Norway spruce

Our aim was to compare enzyme activities (tannase, polyphenol oxidase and protease) with concentrations of tannins and their ability to precipitate proteins in the litter layer and the humus layer under silver birch (Betula pendula Roth.) and Norway spruce (Picea abies L.). We also estimated the influence of these enzymes on protein-tannin complexes and the influence of tannins on proteolytic activity. The study site was a tree species experiment in Eno, middle-eastern Finland, having three replicated plots dominated by 42-year-old silver birch and Norway spruce. Our hypotheses were (1) tree species and soil layer have an influence on tannin concentrations and enzyme activities, (2) that tannin and protein concentrations in soil organic horizon are positively correlated with enzyme activities and (3) that the enzymes studied have the ability to degrade tannin-protein complexes and that tannins can inhibit proteolytic activity. Concentrations of total tannins and hydrolysable tannins, and tannase and proteolytic activities were higher in the humus layer than in the litter layer. In general the highest values of concentrations of total tannins and hydrolysable tannins and enzyme activities were obtained for the birch humus layer, but the concentrations of condensed tannins and proteins were highest in the litter layer and under spruce. A strong correlation between substrate concentration and enzyme activity was found between hydrolysable tannins and tannase activity. Polyphenol oxidase showed similar activities in both layers. To study the influence of enzymes on protein-tannin complex we synthesized such complexes using bovine serum albumin and either condensed tannins from silver birch and Norway spruce needles or a hydrolysable tannin, tannic acid. Studies with commercial enzymes and enzymes extracted from the soil showed some decrease in tannin concentration of the tannin-protein complex over time, but surprisingly, only a negligible decrease in protein concentration. Complexes of protein with condensed tannins were more recalcitrant than tannic acid-protein complexes. Tannins, depending on the concentration and chemical structure, tended to inhibit proteolytic activity. Our results indicate that protein-tannin complexes are relatively recalcitrant since the enzymes studied here do not effectively release protein from the complexes. Also proteolytic activity and the concentration of extractable proteins seem to be low in soil. However, tannin-degrading enzymes showed high activities.