Relation of Chlorophyll Fluorescence Sensitive Reflectance Ratios to Carbon Flux Measurements of Montanne Grassland and Norway Spruce Forest Ecosystems in the Temperate Zone

We explored ability of reflectance vegetation indexes (VIs) related to chlorophyll fluorescence emission (, ) and de-epoxidation state of xanthophyll cycle pigments (PRI, calculated as ) to track changes in the CO2assimilation rate and Light Use Efficiency (LUE) in montane grassland and Norway spruce forest ecosystems, both at leaf and also canopy level. VIs were measured at two research plots using a ground-based high spatial/spectral resolution imaging spectroscopy technique. No significant relationship between VIs and leaf light-saturated CO2assimilation () was detected in instantaneous measurements of grassland under steady-state irradiance conditions. Once the temporal dimension and daily irradiance variation were included into the experimental setup, statistically significant changes in VIs related to tested physiological parameters were revealed. ΔPRI and Δ() of grassland plant leaves under dark-to-full sunlight transition in the scale of minutes were significantly related to (). In the daily course, the variation of VIs measured in one-hour intervals correlated well with the variation of Gross Primary Production (GPP), Net Ecosystem Exchange (NEE), and LUE estimated via the eddy-covariance flux tower. Statistical results were weaker in the case of the grassland ecosystem, with the strongest statistical relation of the index with NEE and GPP.

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Effects of stump extraction on the carbon sequestration in Norway spruce forest ecosystems under varying thinning regimes with implications for fossil fuel substitution

GCB Bioenergy ◽

10.1111/gcbb.12010 ◽

2012 ◽

Vol 5 (4) ◽

pp. 445-458 ◽

Cited By ~ 17

Author(s):

Ashraful Alam ◽

Seppo Kellomäki ◽

Antti Kilpeläinen ◽

Harri Strandman

Keyword(s):

Carbon Sequestration ◽

Norway Spruce ◽

Forest Ecosystems ◽

Fossil Fuel ◽

Spruce Forest ◽

Fuel Substitution ◽

Norway Spruce Forest

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Assessing the Contrasting Effects of the Exceptional 2015 Drought on the Carbon Dynamics in Two Norway Spruce Forest Ecosystems

Atmosphere ◽

10.3390/atmos12080988 ◽

2021 ◽

Vol 12 (8) ◽

pp. 988

Author(s):

Caleb Mensah ◽

Ladislav Šigut ◽

Milan Fischer ◽

Lenka Foltýnová ◽

Georg Jocher ◽

...

Keyword(s):

Norway Spruce ◽

Large Scale ◽

Forest Ecosystems ◽

Heat Waves ◽

Ecosystem Respiration ◽

Vapour Pressure Deficit ◽

Climate Projections ◽

Summer Drought ◽

Spruce Forest ◽

Norway Spruce Forest

The occurrence of extreme drought poses a severe threat to forest ecosystems and reduces their capability to sequester carbon dioxide. This study analysed the impacts of a central European summer drought in 2015 on gross primary productivity (GPP) at two Norway spruce forest sites representing two contrasting climatic conditions—cold and humid climate at Bílý Kr̆íz̆ (CZ-BK1) vs. moderately warm and dry climate at Rájec (CZ-RAJ). The comparative analyses of GPP was based on a three-year eddy covariance dataset, where 2014 and 2016 represented years with normal conditions, while 2015 was characterized by dry conditions. A significant decline in the forest GPP was found during the dry year of 2015, reaching 14% and 6% at CZ-BK1 and CZ-RAJ, respectively. The reduction in GPP coincided with high ecosystem respiration (Reco) during the dry year period, especially during July and August, when several heat waves hit the region. Additional analyses of GPP decline during the dry year period suggested that a vapour pressure deficit played a more important role than the soil volumetric water content at both investigated sites, highlighting the often neglected importance of considering the species hydraulic strategy (isohydric vs. anisohydric) in drought impact assessments. The study indicates the high vulnerability of the Norway spruce forest to drought stress, especially at sites with precipitation equal or smaller than the atmospheric evaporative demand. Since central Europe is currently experiencing large-scale dieback of Norway spruce forests in lowlands and uplands (such as for CZ-RAJ conditions), the findings of this study may help to quantitatively assess the fate of these widespread cultures under future climate projections, and may help to delimitate the areas of their sustainable production.

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