The management of aspen stands on the example of experimental area at Järvselja demonstration and experimental area, district 243

Magistritöö koostamiseks viidi läbi mõõtmisi Järvselja ÕKMKa kvartali 243 eraldusel 6 asuvas haava harvendusraie katsealal ning selle kõrval olevas haava loodusliku uuenemise katsealal. Mõõtmistulemuste analüüsimisel kirjeldati Haavametsa Haaviku kasvukäiku ning uuriti puude raiejärgset juurdekasvu suurenemist. Kirjanduse põhjal antakse töös ülevaade hariliku haava (Populus tremula) bioloogilistest iseärasustest ning peamistest haavikute kahjustajatest. Magistritöö eesmärgiks oli mõõtmisandmete ning harvendusraie alase kirjanduse kaudu kirjeldada Eesti haavikutele sobilikku majandamisskeemi, selgitada välja magistritöö autori bakalaureusetöös täheldatud triploidse haavanoorendiku aeglase kasvu põhjus, kirjeldada Haavametsa Haaviku kasvukäiku ning analüüsida raiejärgselt tekkiva haava juurevõsulise uuenduse võimalusi ja riske. Magistritöö peamine hüpotees on, et triploidne haab (Populus tremula f. gigas) on suure biomassi produktsiooniga ning suudab konkureerida teiste kiirekasvuliste kodumaiste lehtpuudega. Alamhüpoteesina kontrolliti, kas haavataelik (Phellinus tremulae) võib levida juurte kaudu vanast metsapõlvkonnast tekkivasse juurevõsulisse uuendusse. Haavametsa Haaviku eraldusel 6 asuval 3. proovitükil kasvava triploidse haaviku tagavara on 849 tm/ha ning üldproduktsioon koos harvendusraiel välja raiutud puiduga ning teise rinde pärnadega 1197 tm/ha. Loodusliku uuenemise katsealal kasvava triploidse haava noorendiku uurimisel selgus DNA-analüüside põhjal, et tumenenud puiduga noortes haabades esines perekondade Cryptococcus ja Helotiales esindajaid ning Ameerika haaval tüvevähki tekitav Cryptosphaeria ligniota, mis põhjustab noorte puude suremist ning alandab puistu biomassi produktsiooni. Tegemist on Cryptosphaeria ligniota esmaleiuga Eestis ning magistritöö autori hinnangul võibolla ka selle patogeeni esmaleiuga triploidsel haaval. Töö tulemusena selgus, et Eestis tingimustes ei ole soovituslik esimesel 10 aastal haavikuid harvendada, kuna on suur ulukikahjustuse oht. Intensiivsemad raied peaks alustama 20-aastases puistus, kui ulukikahjustuse oht on vähenenud.To compile this Master's Thesis the measurements were conducted at aspen thinning experimental area at Järvselja demonstration and experimental area, district 243, sixth allocation and at the experimental area of aspen regeneration next to it. Analyzing the collected data the growth of famous Haavametsa aspen stand was decribed and the increase of post-felling increment was studied. Based on literature biological peculiarities of common aspen (Populus tremula) and the most frequent browsing of aspen stands were described. The aim of this thesis is to describe, based on the collected data and the literature about thinning, the best forest management concept for aspen stands in Estonian conditions, ascertain the reason of slow growth of young triploid aspen stands that was observed in the Bachelor's Thesis of the author of the current Master's Thesis, to describe the growth of Haavametsa aspen stand and to analyse the possibilities and threats of post-felling aspen suckering regeneration. The main hypothesis of this Master's Thesis is that triploid aspen (Populus tremula f. gigas) has high biomass production and can compete with other fast-growing domestic broad-leaf trees. As a sub-hypothesis it was examined whether aspen phellinus can spread through roots from old forest generation to suckering regeneration. The volume of triploid aspen growing on the third sample plot in sixth allocation in Haavametsa aspen stand is 849 cm/ha and the overall production together with the wood harvested in thinning and second layer lindens is 1197 cm/ha. Examining the young triploid aspen stand growing on the experimental area of natural regrowth, based on DNA-analysis, it appeared that among young aspens, which had darkened wood, the representatives of Cryptococcus and Helotiales families were discovered and among quaking aspens (Populus tremuloides) Cryptosphaeria ligniota, which causes canker, was discovered which, in turn, causes young trees to die and lowers the biomass production of the stand. It is the first case of Cryptosphaeria ligniota in Estonia and in the opinion of the author of this thesis it could also be the first case of this pathogen found on triploid aspen. As the result of the thesis it is not recommended to start aspen stand thinning in Estonian conditions during the first 10 years, because of the high threat of elk browsing. Felling should start in 20-year-old stands when the threat of elk browsing has decreased