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Iskalni niz: "avtor" (Eva Dařenová) .

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Harvesting intensity and tree species affect soil respiration in uneven-aged Dinaric forest stands
Matjaž Čater, Eva Dařenová, Primož Simončič, 2021, izvirni znanstveni članek

Povzetek: Forest management, especially thinning and harvesting measures, has a significant impact on the forest carbon balance especially in the forests with long-term continuous cover history. We measured soil CO2 efflux (Rs) in three forest complexes of mixed, uneven-aged Dinaric forests with predominating silver fir (Abies alba Mill.), beech (Fagus sylvatica L.), and Norway spruce (Picea abies Karst.). Rs was measured after removal of mature forest stands with 50% and 100% intensity of living stock and compared with Rs on the control plots without any applied silvicultural measures. Rs was measured monthly in three consecutive 2012, 2013 and 2014 growing periods. Soil CO2 efflux increased after harvest of both intensities in all studied forest stands. The biggest increase was measured in beech stands and amounted up to 47 and 69% for 50% and 100% harvest intensities, respectively. The effect of harvest on Rs in spruce and fir stands was similar - up to 26% for 50% harvest intensity and 48% for 100% harvest intensity. Despite the biggest increase after harvest, Rs in beech stands returned the fastest to the level of the uncut forest and this levelling period (LP) took 14-17 months with a little delay of the stands with 100% harvest intensity. The LP for all fir stands, for spruce stands with 50% harvest intensity and for one spruce stand with 100% harvest intensity, was 26-29 months. At two spruce stands with 100% harvest intensity we did not record Rs levelling during our three-year study. This study involved forest stands of three predominating tree species growing under the same conditions, which allowed us to determine the species-specific sensitivity of soil CO2 efflux to the different harvesting intensities.
Ključne besede: harvesting intensity, soil CO2 efflux, silviculture, carbon release, silver fir forests, Beech forestrs, Norway spruce forests
Objavljeno v DiRROS: 08.10.2020; Ogledov: 842; Prenosov: 305
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Effect of spatial scale and harvest on heterogeneity of forest floor CO2 efflux in a sessile oak forest
Eva Dařenová, Matjaž Čater, 2020, izvirni znanstveni članek

Povzetek: Soil respiration is the second largest flux of carbon between terrestrial ecosystems and the atmosphere and it is substantially sensitive to climate change. Monitoring CO2 efflux and its upscaling from field measurements to the ecosystem level is a complex task, due to the high spatial and temporal variability of the fluxes. Human intervention, e.g. through forest harvest, may change both CO2 efflux and its spatial heterogeneity. The objective of our study was to quantify spatial heterogeneity of soil CO2 efflux within and among plots distributed within a topographically variable sessile oak forest stand before and after harvesting. Forest floor CO2 efflux, soil temperature and soil water content were measured monthly in a sessile oak forest during two growing seasons: one before and one after harvesting. Stand structure characteristics (gap fraction, leaf area index, tree number and size) and the amount of understory also were determined. Relationships between individual variables and spatial heterogeneity were analyzed. The small-scale spatial heterogeneity (expresses as the coefficient of variation) of forest floor CO2 efflux and soil water content (SWC) in the undisturbed forest was low, at maximum 0.22 and 0.13, respectively. Studied variables had no effect on spatial heterogeneity of forest floor CO2 efflux except for the amount of understorey vegetation which positively correlated with forest floor CO2 efflux. Although the studied forest was situated in topographically variable terrain, we observed that inter-plot heterogeneity of forest floor CO2 efflux was lower than that within plots. Stand harvest increased the intra-plot heterogeneity of forest floor CO2 efflux but did not affect the inter-plot heterogeneity. This leads to the conclusion that the number of positions within an individual plot should increase after harvest but the number of plots may remain unchanged to determine adequately ecosystem forest floor CO2 efflux.
Ključne besede: gap fraction, LAI, Quercus petraea, soil respiration, soil water content
Objavljeno v DiRROS: 20.02.2020; Ogledov: 1307; Prenosov: 207

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