Carbon fluxes and storages in Estonian coniferous and mixed stands and the effect of different harvesting methods on carbon sequestration
| dc.contributor.advisor | Uri, Veiko (advisor) | |
| dc.contributor.advisor | Kukumägi, Mai (advisor) | |
| dc.contributor.author | Sepaste, Agnes | |
| dc.contributor.department | Institute of Forestry and Rural Engineering | eng |
| dc.contributor.other | Huuskonen, Saija (opponent) | |
| dc.date.accessioned | 2026-07-31T18:05:56Z | |
| dc.date.available | 2026-07-31T18:05:56Z | |
| dc.date.defensed | 2026-08-26 | |
| dc.date.issued | 2026 | |
| dc.description | A Thesis for applying for the degree of Doctor of Philosophy in Forestry. | eng |
| dc.description | Väitekiri filosoofiadoktori kraadi taotlemiseks metsanduse erialal. | est |
| dc.description.abstract | ABSTRACT. Forest management in Northern Europe has traditionally focused on even-aged coniferous stands. However, due to changing climate conditions, the management of mixed stands and the maintenance of continuous forest cover have received increasing attention. At the same time, knowledge regarding the production capacity and carbon (C) balance of mixed forests and forest managed under continuous-cover forestry remains relatively limited. The biometric C budgeting approach was used to examine C cycling in the studied chronosequences and to evaluate the effect of different management methods on ecosystem C balance. Both mixed silver birch–Norway spruce stands as well as pure Norway spruce stands demonstrated considerable C sinks potential, with net ecosystem production (NEP) values ranging from 1.2 to 7 t C ha⁻¹ yr⁻¹ across studied chronosequences. In both dataset current annual production peaked in middle-aged stages. The net primary production (NPP) of trees served as the main driver of dynamics of C sequestration, while soil heterotrophic respiration remained relatively stable across the successional gradient of the stands. However, the average C stock per age class accumulated in the trees was higher in pure stands than in mixed forests, at 142.5 and 97.5 t C ha⁻¹ respectively. The short-term effects of clear-cutting versus transitional selection cutting on NEP were evaluated in mature Scots pine stands. Although the applied partial harvesting in mature Scots pine stands reduced annual NPP by 20–40%, thinned stands remained C neutral or acted as C sinks, annual NEP values varied between -0.2 and 1.9 t C ha-1 yr-1. Clear-cut areas acted as C sources with annual C loss at -2.4 to -4.1 t C ha-1 yr-1. These findings demonstrate that both stand composition and management practices influence forest C dynamics and should be considered in climate-smart forest management strategies. | eng |
| dc.description.abstract | LÜHIKOKKUVÕTE. Põhja-Euroopa metsanduses on traditsiooniliselt keskendutud ühevanuselistele okaspuupuistute kasvatamisele. Muutuvate kliimatingimuste tõttu on aga segapuistute kasvatamine ning pideva metsakatte säilitamine pälvinud üha suuremat tähelepanu. Samal ajal on teadmised segametsade ja püsimetsamajanduse mõjust metsade produktsioonivõimele ning süsiniku (C) bilansile endiselt suhteliselt piiratud. Käesolevas töös kasutati biometrilise süsinikubilansi meetodit, et uurida süsinikuringet vaadeldud vanuseridades ning hinnata erinevate majandamisviiside mõju ökosüsteemi süsinikubilansile. Nii segapuistud kui ka puhtkuusikud osutusid tõhusateks C neelajateks, ökosüsteemi aastane C sidumine neis varieerus vahemikus 1,2–7 t C ha⁻¹ a⁻¹. Mõlema valimi puhul saavutas aastane produktsioon maksimumi keskealistes puistutes. Puude aastane netoproduktsioon oli peamine C sidumise dünaamikat määrav tegur, samas kui kumulatiivne CO2 emissioon mullast püsis puistute arengurea ulatuses suhteliselt ühtlasena. Keskmine puudes akumuleerunud C varu oli kuusikute vanusereas suurem kui segametsades, vastavalt 142,5 ja 97,5 t C ha-1. Küpsetes hariliku männi puistutes võrreldi lageraie ja osalise raie (antud uuringus alustava valikraie kontekstis) lühiajalist mõju C sidumisele. Kuigi osaline raie vähendas puistu produktsiooni vahemikus 20–40%, jäid alad C neutraalseks või C sidujateks (-0,2 kuni 1,9 t C ha⁻¹ a⁻¹), samas kui kõik lageraiealad muutusid C allikateks (-2,4 kuni -4,1 t C ha⁻¹ a⁻¹). Tulemused näitavad, et nii puistute liigiline koosseis kui ka majandamisviisid mõjutavad metsade C sidumise dünaamikat ja talletatud C varusid, mida on oluline arvestada kliimatarga metsamajanduse kujundamisel. | est |
| dc.identifier.isbn | 978-9916-91-072-6 (print) | |
| dc.identifier.isbn | 978-9916-91-073-3 (pdf) | |
| dc.identifier.issn | 2382-7076 | |
| dc.identifier.uri | http://hdl.handle.net/10492/10959 | |
| dc.publisher | Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Doctoral Theses of the Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Eesti Maaülikooli doktoritööd | est |
| dc.rights | © Agnes Sepaste, 2026 | |
| dc.rights | info:eu-repo/semantics/openAccess | eng |
| dc.rights.uri | https://www.riigiteataja.ee/en/eli/ee/Riigikogu/act/519062017005/consolide | est |
| dc.subject | continuous-cover forestry | eng |
| dc.subject | mixed-species stands | eng |
| dc.subject | carbon balance | eng |
| dc.subject | net ecosystem production | eng |
| dc.subject | Green University (thesis is related to EMÜ Green University iniciative’s aims) | eng |
| dc.subject | dissertations | eng |
| dc.title | Carbon fluxes and storages in Estonian coniferous and mixed stands and the effect of different harvesting methods on carbon sequestration | eng |
| dc.title.alternative | Süsiniku vood ja varud Eesti okas- ja segametsades ning erinevate raieviiside mõju süsiniku sidumisele | est |
| dc.type | Doctoral Thesis | eng |
| dc.type.qualificationname | PhD | eng |
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