Direct seeding of boreal conifers on freely drained andosols in Southern Iceland

HöfundurÚtgefandiÚtgáfuárÚtgáfustađur
Jón Geir Pétursson, Ađalsteinn SigurgeirssonRALA, Hólaskóli, LBH, Rannsóknastöđ skógrćktar Mógilsá, Garđyrkjuskóli ríkisins, Veiđimálastofnun, Keldur, Landgrćđsla ríkisins, BÍ2004Reykjavík
RitÁrgangurTölublađBls.
Icelandic Agricultural Sciences16-1715-28

Gr-bu16-17-JGP.pdf

Full text (PDF) / Grein í heild í pdf-skjalinu

SUMMARY

The success of a direct seeding trial in southern Iceland was evaluated throughout four growing seasons. The trial involved comparison of the three coniferous species most commonly used in Icelandic forestry: lodgepole pine (Pinus contorta Dougl. var. contorta), Sitka spruce (Picea sitchensis (Bong.) Carr.) and Siberian larch (Larix sibirica Ledeb.) and five seeding methods: (1) control, (2) plastic cone, (3) pyramidal indentations, (4) cover with gravel and (5) cover with pumice. For comparison, one-year old seedlings were planted in the spring and autumn. The seedling emergence for all species and seeding methods was 11.3% after the first summer and 19.0% after the second. Seedling emergence was significantly higher for lodgepole pine (41.3%) than for Sitka spruce (26.8%) and Siberian larch (22.6%). Sowing under a plastic cone gave the highest seedling emergence or an average of 50.3% for all species. Seedling mortality was high after the first winter, except under the cones, where more than 80% of the seedlings survived. After three winters the highest survival was found for lodgepole pine, where 19.7% of the viable seed yielded established seedlings, compared to 10.9% for Siberian larch and 9.2% for Sitka spruce. The number of seeding spots having at least one live seedling after three growing seasons ranged from 50 to 76% for lodgepole pine, 2.5 to 45% for Sitka spruce and 6.6 to 40% for Siberian larch. Survival of planted seedlings differed between planting seasons, with spring planting yielding better survival for Sitka spruce and lodgepole pine and autumn planting for Siberian larch. Lodgepole pine gave the most promising results for establishment by direct seeding. From the fourth year establishment ratios, it can be concluded that the use of plastic cone-shelters is the most promising method of direct seeding and appears to provide establishment success comparable with planting.

Key words: afforestation, conifers, direct seeding, Iceland, seedling emergence, seed predation

YFIRLIT

Bein sáning á frći ţriggja barrtrjátegunda í útjörđ á Suđurlandi

Tilraun var komiđ á fót voriđ 1993 međ beinar sáningar á barrtrjáfrći ađ Mosfelli í Grímsnesi og var hún metin viđ lok fjórđa sumars frá upphafi tilraunar (áriđ 1996). Í tilrauninni var borinn saman árangur af sáningu stafafuru-, sitkagrenis- og rússalerkifrćs međ fimm mismunandi sáningarađferđum, og auk ţess árangur af gróđursetningu ársgamalla plantna sömu tegunda, ađ vori og hausti. Međalspírun alira tegunda viđ lok fyrsta sumars (1993) var 11,3% en 19,0% viđ lok annars sumars (1994). Bein sáning stafafurufrćs gaf hćstu heildarspírun (41,3%, án tillits til sáningarađferđar), marktćkt hćrri en fyrir sitkagreni (26,8%) og rússalerki (22,6%). Sáning međ plastkeilum gaf besta spírun trjáfrćs (50,3%, fyrir allar ţrjár tegundir). Afföll fyrsta vetur tilraunarinnar urđu minnstar hjá ungplöntum sem sáđ hafđi veriđ til undir keilum (80% lifun). Eftir ţrjá vetur reyndust afföll smáplantna minnst hjá stafafuru, ţar sem sáning leiddi til plöntumyndunar (ţriggja ára, lifandi frćplöntu) í 19,7% tilvika, samanboriđ viđ 10,9% hjá rússalerki og 9,2% hjá sitkagreni. Fjöldi sáningarstađa ţar sem var ađ finna lifandi trjáplöntu viđ lok fjórđa sumars frá upphafi tilraunar var á bilinu 50-76% hjá stafafuru, 2,5-45% hjá sitkagreni og 6,6-40% hjá rússalerki. Gróđursetning ađ vorlagi leiddi af sér minnst afföll hjá stafafuru og sitkagreni, en hjá rússalerki voru afföll minni hjá trjáplöntum sem gróđursettar höfđu veriđ ađ haustlagi. Bein sáning virđist einkar efnileg og áhugaverđ ađferđ viđ nýskógrćkt á stafafuru á rýru landi. Árangur af notkun beinna sáninga viđ nýskógrćkt virđist best tryggđur međ notkun plastkeila, en međ ţeirri ađferđ má fyrir minni kostnađ ná sambćrilegum árangri og međ gróđursetningu trjáplantna.