The effect of different harvesting methods on carbon cycling and productivity of forest ecosystems
dc.contributor.advisor | Uri, Veiko (advisor) | |
dc.contributor.advisor | Varik, Mats (advisor) | |
dc.contributor.author | Uri, Marek | |
dc.contributor.department | Institute of Forestry and Engineering | eng |
dc.contributor.other | Palviainen, Marjo (opponent) | |
dc.date.accessioned | 2024-11-11T08:39:08Z | |
dc.date.available | 2024-11-11T08:39:08Z | |
dc.date.defensed | 2024-12-11 | |
dc.date.issued | 2024 | |
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 | The forests of the northern hemisphere are the important natural carbon (C) sinks in terrestrial ecosystems, however, the C sequestration capacity of stands can be significantly affected by different harvesting methods. Clear-cutting is the prevailing forest management method in Northern Europe, and its effect on the C cycle of the site is appreciable. Clear-cuts act as C sources and quantification of the amount of C loss, as well as evaluation of the post harvesting recovery dynamics of C balance are crucial issues. The annual net ecosystem production (NEP) of mesotrophic pine and fertile silver birch clear-cut areas varied between 1.7-1.9 and 0.4-0.5 t C ha-1 yr-1, respectively. The ecosystem turned into a C sink at a stand age of seven years for Scots pine and six years for silver birch. The C payback period, which indicates the time lag for replenishing the cumulative C loss before C balancing, was estimated at age of 12 and 10 years for Scots pine and silver birch, respectively. Shelterwood cutting (SWC) allows avoidance of drastic changes in the landscape and is recognized as an alternative method to clear-cutting. However, the impact of SWC on C stocks and C fluxes of the forest ecosystem is still a relatively poorly studied issue. In the current study, one of the studied stands turned into a C source after SWC, while the other remained a weak C sink (-1.3 and 0.6 t C ha-1 yr-1, respectively). Although in the short term, SWC demonstrated a certain advantage over clear-cut in terms of the C cycle, then for relevant evaluation, the whole rotation cycle should be considered. The net ecosystem exchange for the post-SWC area, measured by the eddy covariance technique in the first post-harvesting year, showed a larger C sink than that estimated by the budgeting method. The above divergence was largely induced by the cumulative uncertainty of NEP, which is inherent in the bottom-up budgeting approach. In Estonia, the more extensive implementation of selective cuttings and the principles of continuous cover forest management in forestry are increasingly highlighted. Based on the results of experimental transitional selective cuttings in mature mesotrophic pine stands it would be possible to maintain the old stand over a longer period in case a considerable amount of timber is removed by repeated cuttings. The results of the simulated further growth dynamics of post-harvested stands showed a considerably lower total wood production over the following 40 years compared to the production of forests formed after clear-cut. | eng |
dc.description.abstract | Lageraied on domineeriv metsade majandamise meetod nii Eestis kui ka Põhja-Euroopas laiemalt, samas on neil suur mõju kasvukoha C ringele. Raiesmikud on paratamatult C allikad, kuid lageraie kliimamõju selgitamisel mängivad olulist rolli nii kumulatiivne C kadu raiesmikel kui ka emiteerunud C tagasisidumiseks kuluv aeg. Uuritud palumännikute raiesmikel olid aastased C emissioonivood 1,8-1,9 t C ha-1 a-1, viljakatel arukase raiesmikel aga 0,4-0,5 t C ha-1 a-1. Männinoorendikud muutusid taas süsinikku siduvateks ökosüsteemideks seitsmendal ja arukaasikud kuuendal lageraie järgsel aastal. Kumulatiivne süsinikuvõlg seoti männikus tagasi 12 a. ja kaasikus 10 a. vanuses puistus. Erinevalt lageraietest võimaldavad turberaied vana metsapõlvkonda asendada järk-järguliselt, vältides järske muutusi maastikus ja aineringetes. Aegjärkne raie küpses palumännikus muutis ühe uuritavatest puistutest C allikaks, teine jäi nõrgaks C sidujaks. Kuigi lühiajaliselt võimaldab aegjärkne raie männikus vähendada vahetut raiejärgset C kadu, tuleb tervikpildi saamiseks võtta arvesse uuenemist ja metsa summaarset puiduproduktsiooni pikema aja vältel. Turbulentsete kovariatsioonide meetodil (EC) mõõdetud süsinikuvood turberaie järgses männikus näitasid suuremat aastast C sidumist, kui bilansi meetodil hinnati. Lahknevuse üheks põhjuseks oli bilansimeetodi rakendamisega kaasnev suurem kumulatiivne vea hinnang, samuti ei arvesta bilansimeetod kõiki ökosüsteemi C voogusid, näit. mükoriisa poolt seotavat C kogust. Eestis valitsevad kõrged ootused valikraiete ja jätkumetsanduse põhimõtete laiemaks rakendamiseks, kuigi teadmisi selles valdkonnas napib. Valikraie põhimõtete rakendamine küpsetes männikutes võimaldab säilitada puistut pikema aja jooksul, samuti on võimalik korduvate raiejärkudega saada arvestatav kogus puitu. Puistute modelleeritud edasine areng näitab, et pikema perioodi jooksul vältel saadav puidu kogus sõltub nende raie-eelsest tagavarast. Võrdluseks simuleeritud lageraie järgsete puistute puiduproduktsioon ületas lähima 40 aasta perspektiivis märgatavalt valikraietega majandatud metsi. Arvestada tuleb ka olulist erinevust puistute hilisemas seisuskorras ja edasises arengus. | est |
dc.description.abstract | Publication of this thesis is supported by the Estonian University of Life Sciences. | eng |
dc.description.sponsorship | Publication of this thesis is supported by the Estonian University of Life Sciences. | eng |
dc.identifier.isbn | 978-9916-91-000-9 | |
dc.identifier.issn | 2382-7076 | |
dc.identifier.uri | http://hdl.handle.net/10492/9506 | |
dc.identifier.uri | https://doi.org/10.15159/emu.144 | |
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 | © Marek Uri, 2024 | |
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 | dissertations | eng |
dc.subject | net primary production | eng |
dc.subject | shelterwood cutting | eng |
dc.subject | carbon budget | eng |
dc.subject | Scots pine | eng |
dc.title | The effect of different harvesting methods on carbon cycling and productivity of forest ecosystems | eng |
dc.title.alternative | Erinevate raieviiside mõju metsaökosüsteemi süsinikuringele ja produktsioonile | est |
dc.type | info:eu-repo/semantics/doctoralThesis | eng |
dc.type.qualificationname | PhD |
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