Artikkelit jotka sisältää sanan 'yield'

We studied the natural regeneration of a cut-over peat bog in the Sumava Mountains, Czech Republic. The spontaneous revegetation by vascular plants has been limited by extreme abiotic conditions left after peat mining. Only 1-2% of the total area was recolonized by Sphagnum mosses. This was mainly because drainage channels are still drying out the bog. Only plants tolerant to water stress such as Juncus effusus, Molinia caerulea, Eriophorum angustifolium and E. vaginatum were able to establish there. A key species colonizing bare surface is a clonal plant E. angustifolium. It forms circular polycormons of densely aggregated ramets. As in other radially spreading phalanx plants, the oldest (central) part of the system gradually dies, previously connected ramets become separated, and ring polycormon becomes open to recolonization by other plant species. We analyzed the relationships between species richness of the ring and their size, percentage litter cover, distance to seed sources, and soil fertility. The number of plant species was higher in the middle of the polycormons. The soil was more fertile in the central area than in the surroundings. We conclude that the restoration of highly disturbed habitats can be facilitated by clonal behavior of pioneer populations.

• Lanta, Faculty of Bilogical Sciences, University of South bohemia, Branisovska 31, CZ-370 05 Ceske Budejovice, CzechRebuplic Sähköposti: ei.tietoa@nn.oo
• Doležal, Sähköposti: ei.tietoa@nn.oo
• Samata, Sähköposti: ei.tietoa@nn.oo

The nutritional status of Scots pine (Pinus sylvestris L.) stands growing on a nitrogen-rich, drained pine mire in western Finland was studied after refertilization using needle analysis and the response of stand volume growth. The main aim was to find out if K-refertilization alone could maintain or increase the volume growth without causing a nutrient imbalance between K and P. The initial fertilization was carried out in 1961 - 62 using PK fertilizer and refertilized in 1976 and 1989 with different combinations of nitrogen (N), phosphorus (P), potassium (K) and boron (B). Needle samples were taken and the tree stands were measured in 1996 and 2001. Peat samples were taken in 2002. According to the needle analysis results, the concentration of P was above the deficiency level in all the treatments in 1995 and 2000. There was a clear shortage of K in the needles collected from the control treatment, but the concentration of K was still adequate 12 years after the latest K refertilization. The volume growth of the stands clearly responded to the 1976 refertilization with K alone, which was probably due to the fact that trees had been suffering from K deficiency before the first refertilization and 14-15 years thereafter. After the second refertilization, the combination of K and P increased the annual volume growth more than refertilization with K alone. This indicates that about 25 years after the initial fertilization, there was already some shortage of P. The highest stand volume was associated with the combined K (1976) and PK (1989) refertilization treatment. Refertilization with N did not increase stand volumes during the study period.

• Rautjärvi, The Finnish Forest Research Institute, Joensuu Research Centre, Box 68, FIN-80101 Joensuu Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo
• Tolonen, Sähköposti: ei.tietoa@nn.oo

Cultivation experiments on D. rotundifolia and D. anglica were carried out in peat beds in Mikkeli, South Finland (61°44’ N, 27°18’ E) in 1992-1997. Plants were propagated by direct sowing and transplanting of small seedlings in peat beds (size 3 m2, depth 0.7 m) filled with non-fertilized peat (pH 4.0). Seed germination, growth, flowering cycle as well as fresh herb and seed yields were measured. To increase the growth, plants were regularly fed milk powder. The 7-methyljuglone, quercetin and kaempferol contents of the flowers, leaves and stems were determined from sown and transplanted, fed and non-fed Drosera plants. Both Drosera species were successfully cultivated in peat beds. Direct sowing in autumn followed by natural winter stratification seemed to be the best propagation method. Flowering started after the second and third growing years. Feeding the plants milk powder increased growth by 27-113%. The fresh yield during the third, fourth and fifth years ranged between 0.05 and 0.9 kg m-2, being highest in the first and second harvest years. Plant density decides the yield of small-sized species. The average yield was about 50 times higher in peat beds than in the nature. Feeding milk powder did not affect the secondary metabolite contents. The 7-methyljuglone content was 13-81% higher in the fed Drosera rotundifolia plants than in the non-fed ones. The quercetin and kaempferol contents were lower in the fed plant, 10-30% and 1-10% lower in D. rotundifolia and 30-60% and 1-15% lower in D. anglica, respectively. According to the results, it seems to be possible to grow Drosera rotundifolia and D. anglica under controlled conditions outside the natural ecosystem. The results also suggest that higher yields can be expected by cultivation of these species.

• Galambosi, Ecological Production, Resource Management, Agricultural Research Centre of Finland, FIN-50600 Mikkeli, Finland Sähköposti: ei.tietoa@nn.oo
• Galambosi, Sähköposti: ei.tietoa@nn.oo
• Repcák, Sähköposti: ei.tietoa@nn.oo

Yield potential and the effect of strict collection on the regeneration of natural populations of Drosera rotundifolia were studied in Finland during 1993-1999. Flowering plants were collected in July from 37 sample plots 1 m2 in size. Plant number, height of flowering plants, fresh weight as well as 7-methyljuglone, quercetin and kaempferol contents were determined. The average plant density was 45-56 plants m-2, and the average fresh weight was 6.3-6.7 g m-2 in the first and second years of collection. Regular and strict collection decreased significantly the population density. The average plant number in the third and seventh years ranged between 21 and 29 plants m-2. The collected fresh weight decreased respectively from 6.7g m-2 to 2.7g m-2. At the end of the vegetation periods the number of new seedlings averaged 188 m-2 on the observation plots, implying that the population may easily regenerate from the seed bank stock of the peat. According to the results of these experiments, the 4H organization elaborated a new, environmentally friendly collection programme for young collectors. The collectors were obliged to leave 5-10 flowering plants to spread seed and to assure natural regeneration of sundew populations.

• Galambosi, Ecological Production, Resource Management, Agricultural Research Centre of Finland, FIN-50600 Mikkeli, Finland Sähköposti: ei.tietoa@nn.oo
• Takkunen, Sähköposti: ei.tietoa@nn.oo
• Repcák, Sähköposti: ei.tietoa@nn.oo

The site index system presented is intended as support for the idea of developing a more hierarchical and integrated forest classification system in Finland. The data used were obtained from stands growing on old permanent experimental plots laid out in drainage areas in southern Finland. The model, describing the post-drainage development of stand dominant height as a function of drainage age (time elapsed since drainage), is based on successive measurement data (465 observations), collected from 89 plots, each representing a single stand. The site indices H40dr are post-drainage dominant height values 40 years since drainage, given in 2-meter classes. Post-drainage dominant height is defined as the difference between the current dominant height and the dominant height at the time of drainage. In classification work, one needs to know (or measure) the two aforementioned height characteristics, together with age since drainage. If the dominant height at the time of drainage is not known, it can be estimated from a function presented herein and based on current dominant height and drainage age. The mean annual volume increments at 40 years since drainage (MAI40) are also presented. There is still a need for examining separately the accuracy of the model with new data from spruce-, pine- and birch-dominated stands, collected for numerical constructions of site index curves. Therefore, the site index model and its characteristics must be seen more as outlines than as a final system for practical application. A well-functioning ditch network is a default when applying the site index curves.

• Gustavsen, The Finnish Forest Research Institute, Joensuu Research Station, P.O.Box 68, FIN-80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo

(Acorus calamus L.) ja mustuvapajun (Salix myrsinifolia Salisb) viljelykokeita. Kalmojuurta ja mustuvapajua viljeltiin Juvan Pakinsuolla (61° 50’ N/27° 52’ E) ja Mikkelin Kovalansuolla (61° 46’ N/27° 18’ E). Lisäksi pajua viljeltiin kivennäismaalla MTT:n Mikkelin Karilan tutkimusasemalla (61°44’ N/ 27°18’ E). Suonpohjapeltojen happamuus oli 4,3 ja 4,8; kokeet perustettiin joko lannoittamattomille ja kalkitsemattomille tai lannoitetuille ruuduille. Lannoitetuissa ruuduissa käytettiin 15000 kg ha–1 kalkkia ja NPK-lannoitusta 75-90-300 kg ha–1. Kolmen kalmojuurikannan taimia istutettiin 80 cm × 40 cm:n etäisyydelle ja viiden mustuvapajukannan juurrutettuja varsipistokkaita istutettiin 60 cm × 50 cm:n välein. Kalmojuuren juurisato mitattiin toisen ja kolmannen kasvukauden lopussa ja sadosta tutkittiin sekä juuriöljyn määrää että koostumusta. Pajukantojen yksivuotisten versojen sato mitattiin joka vuosi elokuussa ja määritettiin salisiinin kokonaispitoisuus. Kalmojuuren tuore- ja kuivajuurisato oli kolmannen kasvukauden jälkeen 6,2 ja 1,7 kg m–2. Kuivan juurisadon öljypitoisuus oli suurin kolmannen vuoden lokakuussa 1,5 %. Öljyn β-asaronin pitoisuus eurooppalaisten triploidikantojen öljyssä oli 11 – 12 %, kun vastaava määrä pohjoisamerikkalaisen diploidikannan öljyssä oli β-asaronia vain 1,8 %. Lannoitetun mustuvapajun yksivuotisten versojen tuore sato oli toisena ja kolmantena vuonna 6,4 ja 10,4 kg m–2. Salisiinin kokonaispitoisuus oli korkein pajun Si-4 kannassa (4,4 %), ja suurimmat pitoisuudet mitattiin elokuun alussa. Suopellolta ja kivennäismailta saatiin määrältään ja laadultaan samanlaiset sadot. Viljelykoetuloksien mukaan kalmojuurta ja mustuvapajua voidaan viljellä suonpohjalla. Sadonkorjuun toteuttaminen on kuitenkin eräs merkittävä viljelyn pullonkaula. Lisää tutkimusta tarvittaisiinkin laajemmassa tuotantomittakaavassa mm. koneellisen sadon korjuun edellytysten selvittämiseksi.

• Galambosi, Bertalan Galambosi, Maatalouden tutkimuskeskus, Kasvintuotannon tutkimus, Karilantie 2A, 50600 Mikkeli, email: bertalan.galambosi@mtt.fi Sähköposti: ei.tietoa@nn.oo
• Jokela, Sähköposti: ei.tietoa@nn.oo