Valgustusraie mõju viljakate kasvukohtade kaasikute (Betula sp.) arengule
Laen...
Kuupäev
2024
Kättesaadavus
04.09.2024
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Kaskede (Betula) tähtsust Eesti metsamajanduses ei saa alahinnata. Nende potentsiaali reaaliseerimiseks on oluline ja tähtis kaasikuide õigesti majandada. Valgustusraiete abil on võimalik puistust kujundada majanduslikult hea ning kvaliteetne puistu. Seni on valgustusraiete mõju kaasikute arengule vähe uuritud.
Töö eesmärk on uurida valgustusraie mõju kaasikute kasvule ning nende võra arengule, mida tehti jänesekapsa kasvukohatüübi 9-aastases arukaasikus ja 15-aastases jänesekapsa-kõdusoo sookaasikus. Mõlemal alal olid läbiraiumata kontrollvariant ja katsevariandid tihedustega 2500 ja 1500 puud hektarile. Haage katsealal olid veel katsevariandid tihedustega 3500 ja 1000 puud hektarile. Katsealad rajati 2019. aastal varasema projekti käigus, kus autor ei osalenud. Käesoleva töö jaoks viidi välitööd läbi 2023 aasta augustis, mil kõik alad takseeriti ning määrati puistute keskmine võra pikkus ja laius, võra alguspunkt ning leiti keskmine võra osakaal puistu kõrgusest.
Valgustusraie omas puude kasvule positiivset mõju. Mõlemal alal olid nii puistu keskmine rinnasdiameeter kui ka kõrgus kõikides raiutud katsevariantides suurem kui kontrollalal. Nooremal Lennujaama katsealal oli 5 kasvuperioodi peale valgustusraiet puistu tagavara juba taastunud ning katsevariandis 2500 puud ha-1 ületas tagavara kontrollala vastavat näitajat. Haagel, kus algselt kõrgema puistu tiheduse tõttu oli väljaraie suurem, oli kõikidel katsevariantidel puistu tagavara madalam kui kontrollalal.
Valgustusraiel oli selge positiivne mõju puude võrade laius- ja pikkuskasvule. Hõredamas ja nooremas Lennujaama katsealal oli kontrollalal keskmine elusvõra osakaal 47±20%, kuid läbiraiutud aladel oli vastav näitaja ligikaudu 76%. Haage kontrollalal oli eluvõra osakaal vaid 30,0±8,4%, kuid katsevariantidel 2500, 1500 ja 1000 puud hektarile oli see vahemikus 63–66% ja katsevariandis 3500 puud hektarile 48±6%. Mõlemal katsealal erinesid kõikide võra näitajate raiutud alade väärtused statistiliselt usaldusväärselt (p<0,05) kontrollalade vastavatest väärtustest.
The economic importance of birch (Betula) in Estonian forestry cannot be underestimated. In order to realize the potential of birch stands, it is important to manage them properly. With the help of pre-commercial thinnings (PCT), it is possible to form a stand with higher quality from the economical and timber quality point of view. The aim of this study is to investigate the impact of thinning on the growth of birch stands and on the development of the crowns. So far, the respective studies are lacking. The study was conducted in two test sites: Lennujaama site (9-year-old silver birch stand, Oxalis site type) and Haage site (15-year-old downy birch stand, Oxalis drained swamp site type). Both areas had unthinned control plots and plots where heavy and light PCT was carried out with the remaining density of 1,500 and 2,500 trees ha-1, respectively. In the Haage site, there were also experimental plots with densities of 3500 and 1000 trees per hectare. Both sites were established in 2019 as part of a previous project in which the author did not participate. For the present study, fieldwork was carried out in August 2023, during which all areas were assessed, and the average crown length and width, crown base height, and the average crown proportion of the stand height were determined. Five growing seasons after the PCT, the mean breast height diameter and height of the stand were greater in all thinned plots compared to the control area at both sites. In the younger Lennujaama site, the stand volume had already recovered after five growing seasons post-thinning, the stand volume of the light thinned plot exceeded the respectiv value of the control plot. At Haage site, the PCT for reaching the target density was more intensive due to the higher initial density. Thus, the stand volume had not recovered, being lower in all thinned plots, compared to the control. The PCT had positive impact on the width and length growth of tree crowns. In the sparser and younger Lennujaama area, the average live crown ratio in the control plot was 47±20%, in the thinned areas, the respectiev value was approximately 76%. In Haage control plot, the live crown ratio was only 30.0±8.4%, ranging around 63–66% in the thinned plots, however in the plot with 3500 trees per hectare, it was 48±6%. In both areas, all crown metrics in the thinned plots differed statistically significantly (p<0.05) from the respective values of the control plots.
The economic importance of birch (Betula) in Estonian forestry cannot be underestimated. In order to realize the potential of birch stands, it is important to manage them properly. With the help of pre-commercial thinnings (PCT), it is possible to form a stand with higher quality from the economical and timber quality point of view. The aim of this study is to investigate the impact of thinning on the growth of birch stands and on the development of the crowns. So far, the respective studies are lacking. The study was conducted in two test sites: Lennujaama site (9-year-old silver birch stand, Oxalis site type) and Haage site (15-year-old downy birch stand, Oxalis drained swamp site type). Both areas had unthinned control plots and plots where heavy and light PCT was carried out with the remaining density of 1,500 and 2,500 trees ha-1, respectively. In the Haage site, there were also experimental plots with densities of 3500 and 1000 trees per hectare. Both sites were established in 2019 as part of a previous project in which the author did not participate. For the present study, fieldwork was carried out in August 2023, during which all areas were assessed, and the average crown length and width, crown base height, and the average crown proportion of the stand height were determined. Five growing seasons after the PCT, the mean breast height diameter and height of the stand were greater in all thinned plots compared to the control area at both sites. In the younger Lennujaama site, the stand volume had already recovered after five growing seasons post-thinning, the stand volume of the light thinned plot exceeded the respectiv value of the control plot. At Haage site, the PCT for reaching the target density was more intensive due to the higher initial density. Thus, the stand volume had not recovered, being lower in all thinned plots, compared to the control. The PCT had positive impact on the width and length growth of tree crowns. In the sparser and younger Lennujaama area, the average live crown ratio in the control plot was 47±20%, in the thinned areas, the respectiev value was approximately 76%. In Haage control plot, the live crown ratio was only 30.0±8.4%, ranging around 63–66% in the thinned plots, however in the plot with 3500 trees per hectare, it was 48±6%. In both areas, all crown metrics in the thinned plots differed statistically significantly (p<0.05) from the respective values of the control plots.
Kirjeldus
Bakalaureusetöö
Metsanduse õppekaval
Märksõnad
bakalaureusetööd, valgustusraie, arukask, sookask, võra areng