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Effects of canopy gaps on soil respiration and microbial activity in uneven-aged Norway spruce stands

Show simple item record 2019-09-04T07:47:42Z 2019-09-04T07:47:42Z 2019-09-04
dc.title Effects of canopy gaps on soil respiration and microbial activity in uneven-aged Norway spruce stands en
ethesis.discipline.URI none und
ethesis.faculty Maatalous-metsätieteellinen tiedekunta fi
ethesis.faculty Faculty of Agriculture and Forestry en
ethesis.faculty Agrikultur- och forstvetenskapliga fakulteten sv
ethesis.faculty.URI Helsingin yliopisto fi University of Helsinki en Helsingfors universitet sv
dct.creator Roth, Eva-Maria
dct.issued 2019
dct.language.ISO639-2 eng
dct.abstract Uneven-aged forest management with selective cutting might hold the potential to limit carbon emissions from the soil after harvesting, compared to rotation forest management with clear-cutting, which is currently more common in boreal forests. The permanently remaining tree cover in uneven- aged forests protects the soil and the microclimate within the stand. It is still poorly understood how selective harvesting affects the carbon fluxes and pools of boreal forests. The aim of this research was to find patterns in the soil respiration and soil carbon content in uneven aged stands that are related to canopy gaps resulting from harvesting operations. I tried to assess the effects of the light, soil temperature and soil moisture conditions in canopy gaps on soil respiration, soil carbon content, microbial decomposition and microbial biomass carbon in order to draw conclusions how uneven aged forest management should be adjusted to avoid carbon losses from the soil. Soil respiration was measured during the summer 2018 on two uneven-aged Norway spruce (Picea abies Karst) stands in Lapinjärvi, southern Finland. Measurements were taken with a mobile closed chamber at fixed measuring points under canopy and in canopy gaps. Soil moisture and soil temperature were measured alongside the respiration measurements. Soil cores were collected at each point to a depth of 30 cm in order to determine carbon and nitrogen stocks. The microbial biomass carbon was analysed at each point with the chloroform fumigation extraction method and the microbial decomposition was determined with the teabag method. The Global Light Index (GLI) and the canopy openness were derived from hemispherical pictures to assess the gap size. I found that the soil respiration in canopy gaps was in average 0.0243 mg CO2 s-1 m-2 higher then under canopy. Soil temperature and soil moisture however did not differ between the points in canopy gaps and under canopy and neither did microbial biomass carbon or the microbial decomposition. Microbial decomposition and microbial biomass C differed strongly between the two study plots and were not correlated with the soil respiration. C and N stocks were higher in canopy gaps than under canopy, but the carbon-to-nitrogen ratio was not affected by the canopy gaps. A statistical relationship between GLI or canopy openness could not be confirmed with neither soil respiration, nor soil carbon or microbial decomposition. The main driver affecting soil respiration and C and N stocks in mineral soil was soil temperature. We modelled soil respiration with the collected data. The best fitting model was selected by comparing the second order Akaike Information Criterions. It included soil temperature as fixed effect variable and the collars and time of measurement as random effect variables. The results confirm that gaps have an influence on soil respiration; however, the gap size seems to be less important. Soil respiration is influenced by a number of factors and complex interactions. The increased soil respiration in the gaps is probably caused by a higher autotrophic respiration by roots and mycorrhiza. en
dct.subject Uneven-aged Forest Structure en
dct.subject Continuous Cover Forest Management en
dct.subject Soil respiration en
dct.subject Soil CO2 Efflux en
dct.subject Gap Dynamics en
dct.language en
ethesis.language English en
ethesis.language englanti fi
ethesis.language engelska sv
ethesis.supervisor Berninger, Frank
ethesis.thesistype pro gradu -tutkielmat fi
ethesis.thesistype master's thesis en
ethesis.thesistype pro gradu-avhandlingar sv
dct.identifier.ethesis E-thesisID:a0bde487-c2a4-4514-9b25-708b956de7cf
ethesis-internal.timestamp.reviewStep 2019-06-25 10:44:48:246
ethesis.principalprofessor Mäkelä, Annikki
dct.identifier.urn URN:NBN:fi:hulib-201909043380
dc.type.dcmitype Text
ethesis.facultystudyline Metsien ekologia ja käyttö fi
ethesis.facultystudyline Forest Ecology and Management en
ethesis.facultystudyline Skoglig ekologi och resurshushållning sv
ethesis.facultystudyline.URI und
ethesis.mastersdegreeprogram Metsätieteiden maisteriohjelma fi
ethesis.mastersdegreeprogram Master's Programme in Forest Sciences en
ethesis.mastersdegreeprogram Magisterprogrammet i skogsvetenskaper sv
ethesis.mastersdegreeprogram.URI und

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