Collembola Communities, 20 Years After the Establishment of Distinct Revegetation Treatments in a Severely Eroded Area in South Iceland

Several restoration methods have been developed to aid ecosystem development from highly degraded Icelandic deserts into fully vegetated functional ecosystems. Despite the critical role of soil biota in many key ecosystem processes, the effect of restoration efforts on soil biota has rarely been explored. We took advantage of a large-scale restoration field experiment, to study the effect of distinct revegetation treatments on the taxonomic and functional composition of Collembola communities. Soil samples were taken from plots (one ha. each), that had received functionally distinct revegetation treatments; i: grass + fertilizer, ii: birch seedlings, iii: willow cuttings, iv: lupine and v: control. We were able to show that different revegetation treatments led to the establishment of distinct collembola communities in terms of density and taxonomic and functional composition, 20 years after the revegetation process had started. Life-forms were responsive to revegetation treatment, which suggests that the treatments had induced successional trajectories that lead to distinct habitat conditions, especially with respect to abiotic stress. In contrast to literature, eu-edaphic species were dominating in plots, which were exposed to high levels of disturbance and fluctuations in abiotic conditions. Further research is needed to unravel, to which extent resource supply and abiotic habitat conditions steer Collembola community development across successional trajectories

Use of NDVI-adjusted PAR for predicting gross primary production in a temperate grassland in Iceland

Gross primary production (GPP) is an important variable to estimate in the global carbon cycle. Estimates of GPP at regional to global scales are critical for understanding ecosystem response to an increased atmospheric CO2 level and for providing objective information for political decisions. The best approach for calculating GPP is through direct measurements of small areas, using either the static-chamber method or eddy covariance technique. Calculating GPP of a whole ecosystem or an entire region is on the other hand problematic. However, scaling up GPP, estimated from direct ground measurements, has increasingly played a role in ecosystem characterization (Lischke et al. 2007). Given that vegetation productivity is directly related to the amount of solar radiation within the plant canopy (Knipling 1970), the simplest method for predicting GPP would be a mathematical function derived from a direct correlation between measured GPP and photosynthetically active radiation (PAR). Many approaches to estimate GPP have been developed based on the work of Monteith (1972), where he suggested that GPP can be expressed as a product of fraction of absorbed photosynthetically active radiation (fAPAR), incident photosynthetically active radiation (PARin) and light use efficiency (LUE), which is the efficiency of the absorbed PAR converted into biomass. Yet an estimate of solar radiation, such as PAR, is not a sufficient indicator of photosynthesis at high northern or southern latitudes because fluctuations in vegetation green mass and solar radiation are not synchronous in time. Several studies have suggested a new remote technique to relate GPP to a product of chlorophyllrelated vegetation indices (VI) and incoming photosynthetic radiation, GPP ∞ VI x PARin, based on Monteith’s logic (Wu et al. 2009, Gitelson et al. 2006, Peng et al. 2013). Numerous vegetation indices are known to indicate the chlorophyll content of vegetation, such as the Red Edge Chlorophyll Index (CIred edge), MERIS terrestrial chlorophyll index (MTCI) (Wu et al. 2009), and the most widely used Normalized Difference Vegetation Index (NDVI) developed by Rouse et al. (1974). Gitelson et al. (2006) successfully estimated GPP with chlorophyll indices, such as NDVI, and indicated GPP as a product of total crop chlorophyll content and PAR. Wu et al. (2009) also verified the utility of chlorophyll content related vegetation indices in the estimation of GPP. The wide acceptance of NDVI, as a proxy for chlorophyll content (e.g. Gutman and Ignatov 1998), and its applicability at both ground and remote levels, make it an attractable option for use in estimating ecosystem productivity. In this study we set out to explore the feasibility of using NDVI alone or NDVI-adjusted PAR for predicting gross photosynthesis of temperate grassland in Iceland through regular ground level measurements of GPP, PAR and NDVI

Verðmat. Ölgerðin Egill Skallagrímsson hf.

Ölgerðin Egill Skallagrímsson hf. eða Ölgerðin er stærsti drykkjavöruframleiðandi á Íslandi og á sér langa og rótgróna sögu í hjörtum Íslendinga. Vörusala félagsins var um 28 milljarðar kr. rekstrarárið 2022/2023 og hagnaður um 2,5 ma.kr. Ölgerðin skráði um 30% af hlutafé sínu í Kauphöll í byrjun júní 2022. Eftirspurn var mikil en alls var um fjórföld umfram eftirspurn í þá hluti sem í boði voru og sýnir það hversu mikill áhugi var og er á fyrirtækinu og framtíð þess. Rannsóknarverkefni þessarar ritgerðar er að meta virði eins hlutar í Ölgerðinni og var það gert með núvirtu sjóðstreymislíkani. Niðurstöður verðmatsins eru að heildarvirði félagsins er 46,7 ma.kr og einn hlutur í Ölgerðinni er virði 14,6 kr

Factors behind the high variation in nitrous oxide emissions in northern managed peatlands

EGU2018-9813201

Factors controlling nitrous oxide emissions from managed northern peat soils with low carbon to nitrogen ratio

201

Carbon and water balance of an afforested shallow drained peatland in Iceland

Funding Information: This research was supported by the Energy Research fund of Landsvirkjun, the National Power Company of Iceland, with an additional support from the Iceland State Electricity. It also contributes to the Nordic CAR-ES project ( C entre of A dvanced R esearch on E nvironmental S ervices from Nordic Forest Ecosystems) and to the SNS 120 program (Nordic Forest Research on Anthropogenic greenhouse gas emissions from organic forest soils: improved inventories and implications for sustainable management). Publisher Copyright: © 2020 The Author(s)Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m−2 yr−1. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m−2 yr−1 as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO2 emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m−2 yr−1. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m−2 yr−1 as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO2 emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.Peer reviewe