Benchmark values for forest soil carbon stocks in Europe: Results from a large scale forest soil survey (original) (raw)
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Ecological Indicators, 2017
Forest soils are important components in the global C-cycle. Regional soil organic carbon (SOC) stock assessments are hampered by low spatial densities of routine soil inventories. In this study, we estimated the SOC stock in the upper meter of forest in the region of Flanders (N. Belgium) using four digital soil mapping techniques, i.e. multiple linear regression (MLR), boosted regression trees (BRT), artificial neural networks (ANN) and least-squares support vector machines (LS-SVM), and compared them with the results of a multi-level spatial generalisation (MLSG) approach. Applied to a collection of 276 soil profiles, we identified the highest groundwater level, clay fraction, tree genus and soil type as key predictors of the SOC stock in the upper 100 cm under forests. Overall, BRT was the most informative as it obtained the best fit (training R 2 of 0.68, cross-validated R 2 of 0.22) and provided insights in the soil system by showing average predictor effects in partial dependence plots. With BRT, the total stock in the upper meter of forest soil (153,544 ha) was estimated to be 26.99 Mt OC, or 17.58 kg m −2 on average. MLSG provided an estimate for only 90% of the forest area and resulted in a larger average stock of 18.22 kg m −2 due to larger predictions for Histosols. As a null model, i.e. assuming that the potential natural dominant tree genus would occur according to the present soil conditions, the SOC stock in the current forest area was estimated at 30.00 Mt OC, or 21.26 kg OC m −2 on average. When the complete non-built-up territory (1,168,850 ha) would be forested analogously, 255.28 Mt OC would be stored, which is more than double the amount of predictions under the actual land cover. The results highlight the importance to conserve and restore carbon hotspots like alluvial forests. New soil inventories should focus on these and other data-scarce land units. Future modelling approaches can benefit from explicitly taking the soil type and tree genus into account as predictors.
The Science of the total environment, 2017
Accurate carbon-balance accounting in forest soils is necessary for the development of climate change policy. However, changes in soil organic carbon (SOC) occur slowly and these changes may not be captured through repeated soil inventories. Simulation models may be used as alternatives to SOC measurement. The Yasso07 model presents a suitable alternative because most of the data required for the application are readily available in countries with common forest surveys. In this study, we test the suitability of Yasso07 for simulating SOC stocks and stock changes in a variety of European forests affected by different climatic, land use and forest management conditions and we address country-specific cases with differing resources and data availability. The simulated SOC stocks differed only slightly from measured data, providing realistic, reasonable mean SOC estimations per region or forest type. The change in the soil carbon pool over time, which is the target parameter for SOC rep...
2005
The global carbon cycle has an important influence on global change. Soil organic carbon (SOC), the largest component of the terrestrial carbon pool, plays a vital role in the terrestrial carbon cycle and therefore knowledge of soil organic carbon pools and fluxes is required. This paper assesses typical values and measures of variation for soil organic carbon contents of soil-land use combinations in Belgium, further termed landscape units (LSU). Data from several heterogeneous data sets collected around the years 1990 and 2000 are used. Their heterogeneity is related to the purpose for which the soil carbon data were collected, the measurement technique, the nature and total depth of the sampled layers and the level of spatial aggregation with which the data were made available. In order to make integrated use of the data and present a spatial and temporal uncertainty assessment of the SOC contents of LSU, we exploit all available information on variability using simple statistical rules. Two thirds of the LSU under arable or grassland have lost SOC between 1990 and 2000 for the upper 20 cm. Approximately one third of these LSU show significantly decreased SOC stocks. The decreases are more pronounced in northern Belgium (region of Flanders), which is possibly due to specific manure regulations. The average SOC content of cropland in the upper 100 cm decreased from 8.8 kg C m À2 in 1990 to 8.4 kg C m À2 in 2000. A comparable decrease is observed under grassland, namely from 13.9 to 13.0 kg C m À2 . For soils, the highest SOC losses occur in the sandy soil associations of northern Belgium. LSU under forest could only be assessed for the year 2000. Forest soils store on average between 14.8 and 15.5 kg C m À2 in the upper 100 cm of mineral soil, depending on forest type. These values are comparable to grassland but significantly higher than cropland. D
European Journal of Forest Research
Healthy soils are the second C sink on Earth, and this sink could last for hundreds or even thousands of years as stable soil organic matter (SOM). Forest soils, in particular, have the potential to store significant amounts of C, however, the amount of C sequestered and the carbon-to-nitrogen (C/N) ratio of soil organic matter (SOM) depend on the vegetation influencing the soil. In the last decades, mixed stands have aroused great interest among the scientific community, but it is still necessary to intensify research on its effect on soils and their C storage capacity. In this study, we assess soil C sequestration potential in soil and litter of mixed and pure stands of Scots pine and beech (Pinus sylvestris–Fagus sylvatica). Three triplets (9 forest plots), two located in Southern Poland and one in Southern Germany were studied. A total of 40 circular subplots of 5 m radius were selected within the triplets, covering a wide range of species mixture, and soil and litter were sampl...
Extrapolating Existing Soil Organic Carbon Data to Estimate Soil Organic Carbon Stocks Below 20 CM
2015
Estimates of forest soil organic carbon stocks across the US are currently developed from expert opinion in STATSGO/SSURGO and linked to forest type. The results are reported to the US EPA as the official United States submission to the UN Framework Convention on Climate Change. Beginning in 2015, however, estimates of soil organic carbon (SOC) stocks will be based on SOC data from soil cores collected in the field (0-10 and 10-20 cm depth). In addition, the Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance suggests these estimates extend to at least 30 cm for all forested lands. This study reports the results of that extrapolation effort. Data for this effort were obtained from the International Soil Carbon Network (ISCN) database, from analyses of more than 500 150 cm deep cores collected from forested sites across the Upper Midwest, and from cores taken at several US Forest Service Experimental Forests. SOC contents were adjusted to 0-10, 10-20, and 20-50 cm...
line 18 and it was made clear that only the biomass vs biomass cover relationship was made using data from 18 stands (a total of 504 of 0.3*0.3 m 2 sample squares), while co-kriging was based on 2501 permanent sample plots with understorey cover measurements. 2. There is only one important point which is not clear so far, the depth of the SOC estimates. I did not find any information about the depth for which SOC was predicted. Sections 2.4.2 and 2.4.3 about Yasso07 & ROMULv models were modified in order to describe how soil depth was defined with models. For Biosoil data this information was given in the section 2.5. 3. From my point of view the structure of those models only allows a prediction for topsoils (0-20 cm), for deeper parts stabilization mechanisms of mineral-associated SOC must be taken into account. At least, model performance should be tested not for the total depth but for different depth increments (e.g. 0-20, 20-40 cm etc.). We agree that models have their strength in estimation of decomposition of litter with varied quality. Both models still have compartments for stabile carbon, but these carbon pools are not depth-specific. In the Yasso07 model this pool is named as "humus" box, while in the ROMULv model this is named as "stabile humus" box (see fig.1). These boxes integrate stabile carbon accumulation from various processes, including that of mineral association. Both models are used in such applications (greenhouse gas inventories, evaluation of the effects of alternative forest management practices) where estimates for deeper soil layers are needed and the models are parametrized accordingly.
Carbon concentrations and stocks in forest soils of Europe
Forest Ecology and Management, 2010
This study presents the results of a series of evaluations of a continent-wide soil database (EU/UN-ECE Level I) with the aim to estimate baseline soil carbon concentrations and stocks. The methodology included the biogeographic stratification of soil carbon measurements throughout Europe using climatic zones derived from the Soil Regions Map of Europe. The presented stock estimates range from 1.3 to 70.8 t C/ha for the O-layer, and from 11.3 to 126.3 t C/ha for the mineral soil 0-20 cm (Germany: 0-30 cm) (5 and 95 percentiles). Histosols were excluded because of methodological differences and data gaps. When looking at the median values of the strata investigated, relationships were found. For example, carbon stocks in the O-layer of sandy soils are distinctly higher than those of fine-textured soils. However, the variability is so high that some of these relationships disappear. For example in western and central Europe, the level of carbon stocks in the mineral soil between shallow soils (Leptosols) and more deeply developed soils (Podzols and Cambisols) do not differ very much. It was also found that just the investigation of topsoils is not sufficient to understand the regional pattern of organic matter in forest soils-unless the subsoil becomes included as well. It is hypothesized that for Europe, the impact of site factors such as climate, texture and relief are difficult to extract from such a database if the data are only stratified according to macro-climatic areas. It has to be considered that the effect of systematic error in the database is quite large (but cannot be identified on the level of the current data availability). In order to receive a first impression of the landscape-level distribution of carbon, a map of carbon concentrations in the topsoil was generated. The results support the relationships found between carbon stocks and site factors, such as climatic zones and soil type. Compared to the much lower carbon concentrations of agricultural soils, the results demonstrate clearly the importance of forest soils for the terrestrial carbon cycling in Europe.