Puistu vanuse määramise meetodite analüüs
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Kuupäev
2019
Kättesaadav alates
10.09.2019
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Puu vanus on metsatakseerimisel ja metsade majandamisel üks olulisemaid tunnuseid.
Kasvava puu vanust määratakse enamasti juurdekasvuproovilt puu aastarõngaid lugedes.
Puistu vanust on lihtsaim ja täpseim määrata ühevanuselises kultuurpuistus, kus kõik puud
on istutatud, külvatud või looduslikult uuenenud enam-vähem samal ajal. Sageli on
puistud aga loodusliku tekkeviisiga või puistus esineb hiljem looduslikult juurde tulnud
puid, mis raskendab puistu vanuse määramist. Omakorda raskendab puistu vanuse
määramist ka asjaolu, et seaduses ei ole otseselt puistuelemendi vanuse definitsiooni.
Käesoleva bakalaureusetöö eesmärkideks on võrrelda erinevaid puistu vanuse määramise
viise ning tuvastada, kas resitograafiga on võimalik hariliku männi, hariliku kuuse ja
arukase puistute vanust piisava täpsusega määrata. Töös kasutatud andmed on kogutud
puudelt, mis kasvavad kahes loodusliku tekkeviisiga puistus Eesti metsa kasvukäigu
püsiproovitükkide 600 ja 595 läheduses. Mõlemalt proovialalt valiti välja 20 juhuslikku
puud mida puuriti esmalt resistograafiga, neist omakorda kümnel puul võeti ka
puursüdamik juurdekasvupuuriga.
Tööst selgub, et erinevate meetoditega arvutatud puistu vanused ei erine suurel määral
üksteisest ja tõenäoliselt ei ole praegune seadusest tulenev vanuse arvutamise valem
põhjendatud, mistõttu võiks puistu vanuse määramisel kasutada traditsioonilist
lähenemist. Oluline oleks puistu vanus seaduses selgelt ära defineerida. Lisaks selgus, et
puu vanuse määramisel resistograafiga võib saada süstemaatiliselt allahinnatud ja
ebarealistlikud tulemused.
The age of trees is one of the most important variables in forest measurement and forest management. The most common way to determine the age of a growing tree is by counting its annual tree-rings from the core sample. It is more evident and easy to determine forest stand age in an even-aged stand because trees are planted or naturally regenerated approximately at the same time. Often in the stands that have regenerated naturally are more complicated to determine the stand age exactly. Also, because of a lack of legislative explanations about stand cohorts it makes harder to have sole determination of stand age. The aim of this paper is to analyse different calculation methods for determining stand age and also to find out how to get sufficiently accurate results for determining the age of Scots pine, Norway spruce and silver birch dominated stands. Data used in this study is collected from the trees of naturally regenerated forest stands near to two permanent sample plots (No. 595 and 600 in the Estonian Network of Forest Research Plots). At first, 20 randomly selected trees were sampled with resistography and secondly, ten trees were simultaneously sampled also by increment borer. The study showed that there is no big difference between the stand age determined by different calculation methods, and therefore the current stand age calculation formula in the forest management regulation is not well justified, the classic determination of stand age is simpler and reliable. It is important that determination of stand age is more clearly stated in the legislation. Study also showed that using resistography in determining the age of a tree gives biased and unrealistic results.
The age of trees is one of the most important variables in forest measurement and forest management. The most common way to determine the age of a growing tree is by counting its annual tree-rings from the core sample. It is more evident and easy to determine forest stand age in an even-aged stand because trees are planted or naturally regenerated approximately at the same time. Often in the stands that have regenerated naturally are more complicated to determine the stand age exactly. Also, because of a lack of legislative explanations about stand cohorts it makes harder to have sole determination of stand age. The aim of this paper is to analyse different calculation methods for determining stand age and also to find out how to get sufficiently accurate results for determining the age of Scots pine, Norway spruce and silver birch dominated stands. Data used in this study is collected from the trees of naturally regenerated forest stands near to two permanent sample plots (No. 595 and 600 in the Estonian Network of Forest Research Plots). At first, 20 randomly selected trees were sampled with resistography and secondly, ten trees were simultaneously sampled also by increment borer. The study showed that there is no big difference between the stand age determined by different calculation methods, and therefore the current stand age calculation formula in the forest management regulation is not well justified, the classic determination of stand age is simpler and reliable. It is important that determination of stand age is more clearly stated in the legislation. Study also showed that using resistography in determining the age of a tree gives biased and unrealistic results.
Kirjeldus
Bakalaureusetöö
Metsanduse õppekaval
Märksõnad
bakalaureusetööd, puistud, vanus, aastarõngad