| 1. |
- Brunner, I., et al.
(författare)
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Fine-root turnover rates of European forests revisited: an analysis of data from sequential coring and ingrowth cores
- 2013
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Ingår i: Plant and Soil. - : Springer Netherlands. - 0032-079X .- 1573-5036. ; 362:1-2, s. 357-372
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86 yr−1 for Fagus sylvatica and 0.88 yr−1 for Picea abies when maximum biomass data were used for the calculation, and 1.11 yr−1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting.
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| 2. |
- Finér, L., et al.
(författare)
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Variation in fine root biomass of three European tree species : Beech (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.)
- 2007
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Ingår i: Plant Biosystems. - : Informa UK Limited. - 1126-3504 .- 1724-5575. ; 141:3, s. 394-405
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Tidskriftsartikel (refereegranskat)abstract
- Fine roots (< 2 mm) are very dynamic and play a key role in forest ecosystem carbon and nutrient cycling and accumulation. We reviewed root biomass data of three main European tree species European beech, (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.), in order to identify the differences between species, and within and between vegetation zones, and to show the relationships between root biomass and the climatic, site and stand factors. The collected literature consisted of data from 36 beech, 71 spruce and 43 pine stands. The mean fine root biomass of beech was 389 g m(-2), and that of spruce and pine 297 g m(-2) and 277 g m(-2), respectively. Data from pine stands supported the hypothesis that: root biomass is higher in the temperate than in the boreal zone. The results indicated that the root biomass of deciduous trees is higher than that of conifers. The correlations between root biomass and site fertility characteristics seemed to be species specific. There was no correlation between soil acidity and root biomass. Beech fine root. biomass decreased with stand age whereas pine root biomass increased with stand age. Fine root biomass at tree level. correlated better than stand level root biomass with stand characteristics. The results showed that there exists a strong relationship between the fine root biomass and the above-ground biomass.
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| 3. |
- Ostonen, I., et al.
(författare)
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Specific root length as an indicator of environmental change
- 2007
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Ingår i: Plant Biosystems. - : Informa UK Limited. - 1126-3504 .- 1724-5575. ; 141:3, s. 426-442
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Tidskriftsartikel (refereegranskat)abstract
- Specific root length (SRL, m g(-1)) is probably the most frequently measured morphological parameter of fine roots. It is believed to characterize economic aspects of the root system and to be indicative of environmental changes. The main objectives of this paper were to review and summarize the published SRL data for different tree species throughout Europe and to assess SRL under varying environmental conditions. Meta-analysis was used to summarize the response of SRL to the following manipulated environmental conditions: fertilization, irrigation, elevated temperature, elevated CO(2), Al-stress, reduced light, heavy metal stress and physical disturbance of soil. SRL was found to be strongly dependent on the fine root classes, i.e. on the ectomycorrhizal short roots (ECM), and on the roots < 0.5 mm, < 1 mm, < 2 mm and 1-2 mm in diameter SRL was largest for ECM and decreased with increasing diameter. Changes in soil factors influenced most strongly the SRL of ECM and roots < 0.5 mm. The variation in the SRL components, root diameter and root tissue density, and their impact on the SRL value were computed. Meta-analyses showed that SRL decreased significantly under fertilization and Al-stress; it responded negatively to reduced light, elevated temperature and CO(2). We suggest that SRL can be used successfully as an indicator of nutrient availability to trees in experimental conditions.
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| 4. |
- Fang, Chao, et al.
(författare)
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Decadal soil warming decreased vascular plant above and belowground production in a subarctic grassland by inducing nitrogen limitation
- 2023
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 240:2, s. 565-576
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Tidskriftsartikel (refereegranskat)abstract
- Below and aboveground vegetation dynamics are crucial in understanding how climate warming may affect terrestrial ecosystem carbon cycling. In contrast to aboveground biomass, the response of belowground biomass to long-term warming has been poorly studied.Here, we characterized the impacts of decadal geothermal warming at two levels (on average +3.3°C and +7.9°C) on below and aboveground plant biomass stocks and production in a subarctic grassland.Soil warming did not change standing root biomass and even decreased fine root production and reduced aboveground biomass and production. Decadal soil warming also did not significantly alter the root–shoot ratio. The linear stepwise regression model suggested that following 10 yr of soil warming, temperature was no longer the direct driver of these responses, but losses of soil N were. Soil N losses, due to warming-induced decreases in organic matter and water retention capacity, were identified as key driver of the decreased above and belowground production. The reduction in fine root production was accompanied by thinner roots with increased specific root area.These results indicate that after a decade of soil warming, plant productivity in the studied subarctic grassland was affected by soil warming mainly by the reduction in soil N.
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| 5. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 6. |
- Sigurdsson, Bjarni D., et al.
(författare)
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Geothermal ecosystems as natural climate change experiments : The ForHot research site in Iceland as a case study
- 2016
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Ingår i: Icelandic Agricultural Sciences. - 1670-567X. ; 29:1, s. 53-71
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Tidskriftsartikel (refereegranskat)abstract
- This article describes how natural geothermal soil temperature gradients in Iceland have been used to study terrestrial ecosystem responses to soil warming. The experimental approach was evaluated at three study sites in southern Iceland one grassland site that has been warm for at least 50 years (GO), and another comparable grassland site (GN) and a Sitka spruce plantation (FN) site that have both been warmed since an earthquake took place in 2008. Within each site type, five ca. 50 m long transects, with six permanent study plots each, were established across the soil warming gradients, spanning from unwarmed control conditions to gradually warmer soils. It was attempted to select the plots so the annual warming levels would be ca. +1, +3, +5, +10 and +20 °C within each transect. Results of continuous measurements of soil temperature (Ts) from 2013-2015 revealed that the soil warming was relatively constant and followed the seasonal Ts cycle of the unwarmed control plots. Volumetric water content in the top 5 cm of soil was repeatedly surveyed during 2013-2016. The grassland soils were wetter than the FN soils, but they had sometimes some significant warming-induced drying in the surface layer of the warmest plots, in contrast to FN. Soil chemistry did not show any indications that geothermal water had reached the root zone, but soil pH did increase somewhat with warming, which was probably linked to vegetation changes. As expected, the potential decomposition rate of organic matter increased significantly with warming. It was concluded that the natural geothermal gradients at the ForHot sites in Iceland offered realistic conditions for studying terrestrial ecosystem responses to warming with minimal artefacts.
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| 7. |
- Verbrigghe, Niel, et al.
(författare)
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Soil carbon loss in warmed subarctic grasslands is rapid and restricted to topsoil
- 2022
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Ingår i: Biogeosciences. - : Copernicus. - 1726-4170 .- 1726-4189. ; 19:14, s. 3381-3393
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Tidskriftsartikel (refereegranskat)abstract
- Global warming may lead to carbon transfers from soils to the atmosphere, yet this positive feedback to the climate system remains highly uncertain, especially in subsoils . Using natural geothermal soil warming gradients of up to +6.4 °C in subarctic grasslands , we show that soil organic carbon (SOC) stocks decline strongly and linearly with warming (-2.8tha-1 °C-1). Comparison of SOC stock changes following medium-term (5 and 10 years) and long-term (>50 years) warming revealed that all SOC stock reduction occurred within the first 5 years of warming, after which continued warming no longer reduced SOC stocks. This rapid equilibration of SOC observed in Andosol suggests a critical role for ecosystem adaptations to warming and could imply short-lived soil carbon-climate feedbacks. Our data further revealed that the soil C loss occurred in all aggregate size fractions and that SOC stock reduction was only visible in topsoil (0-10cm). SOC stocks in subsoil (10-30cm), where plant roots were absent, showed apparent conservation after >50 years of warming. The observed depth-dependent warming responses indicate that explicit vertical resolution is a prerequisite for global models to accurately project future SOC stocks for this soil type and should be investigated for soils with other mineralogies.
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| 8. |
- Walker, Tom W.N., et al.
(författare)
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A systemic overreaction to years versus decades of warming in a subarctic grassland ecosystem
- 2020
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Ingår i: Nature Ecology and Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 4:1, s. 101-108
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Tidskriftsartikel (refereegranskat)abstract
- Temperature governs most biotic processes, yet we know little about how warming affects whole ecosystems. Here we examined the responses of 128 components of a subarctic grassland to either 5–8 or >50 years of soil warming. Warming of >50 years drove the ecosystem to a new steady state possessing a distinct biotic composition and reduced species richness, biomass and soil organic matter. However, the warmed state was preceded by an overreaction to warming, which was related to organism physiology and was evident after 5–8 years. Ignoring this overreaction yielded errors of >100% for 83 variables when predicting their responses to a realistic warming scenario of 1 °C over 50 years, although some, including soil carbon content, remained stable after 5–8 years. This study challenges long-term ecosystem predictions made from short-term observations, and provides a framework for characterization of ecosystem responses to sustained climate change.
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