Admixing other tree species to European beech forests: Effects on soil organic carbon and total nitrogen stocks. A review.

Author(s):  
Stephanie Rehschuh ◽  
Michael Dannenmann

<p>Drought-sensitive European beech forests are increasingly challenged by climate change. Admixing other, preferably more deep-rooting, tree species has been proposed to increase the resilience of beech forests to summer drought. This might not only alter soil water dynamics and availability, but also soil organic carbon (SOC) and total nitrogen (TN) storage in soils. Since information of these effects is scattered, our aim was to synthesize results from studies that compared SOC/TN stocks of beech monocultures with those of mixed beech stands as well as of other monocultures. We conducted a meta-analysis including 40 studies with 208, 231 and 166 observations for forest floor, mineral soil and the total soil profile, respectively. Pure conifer stands had higher SOC stocks compared to beech in general, especially in the forest floor with up to 200% (larch forests). Other broadleaved tree species (ash, oak, lime, maple, hornbeam) showed in comparison to beech lower SOC storage in the forest floor, with little impact on total stocks.  Similarly, for mixed beech-conifer stands we found significantly increased SOC stocks of >10% and a small increase in TN stocks of approx. 4% compared to beech monocultures, which means a potential SOC storage increase of >0.1 t ha<sup>-1</sup>yr<sup>-1 </sup>(transformation of mineral soil to 100 cm depth). In contrast, mixed beech-broadleaved stands did not show a significant change in total SOC stocks. Currently, the influence climatic and soil parameters on SOC changes due to admixture of other tree species is analyzed based on this dataset. This is expected to facilitate an assessment which mixtures with beech have the largest potential towards increasing SOC stocks.</p>

2021 ◽  
Vol 4 ◽  
Author(s):  
Stephanie Rehschuh ◽  
Mathieu Jonard ◽  
Martin Wiesmeier ◽  
Heinz Rennenberg ◽  
Michael Dannenmann

Drought-sensitive European beech forests are increasingly challenged by climate change. Admixing other, preferably more deep-rooting, tree species has been proposed to increase the resilience of beech forests to drought. This diversification of beech forests might also affect soil organic carbon (SOC) and total nitrogen (TN) stocks that are relevant for a wide range of soil functions and ecosystem services, such as water and nutrient retention, filter functions and erosion control. Since information of these effects is scattered, our aim was to synthesize results from studies that compared SOC/TN stocks of beech monocultures with those of beech stands mixed with other tree species as well as monocultures of other tree species. We conducted a meta-analysis including 38 studies with 203, 220, and 160 observations for forest floor (i.e., the organic surface layer), mineral soil (0.5 m depth) and the total soil profile, respectively. Monoculture conifer stands had higher SOC stocks compared to monoculture beech in general, especially in the forest floor (up to 200% in larch forests). In contrast, other broadleaved tree species (oak, ash, lime, maple, hornbeam) showed lower SOC stocks in the forest floor compared to beech, with little impact on total SOC stocks. Comparing mixed beech-conifer stands (average mixing ratio with regard to number of trees 50:50) with beech monocultures revealed significantly higher total SOC stocks of around 9% and a smaller increase in TN stocks of around 4%. This equaled a SOC accrual of 0.1 Mg ha−1 yr−1. In contrast, mixed beech-broadleaved stands did not show significant differences in total SOC stocks. Conifer admixture effects on beech forest SOC were of additive nature. Admixing other tree species to beech monoculture stands was most effective to increase SOC stocks on low carbon soils with a sandy texture and nitrogen limitation (i.e., a high C/N ratio and low nitrogen deposition). We conclude that, with targeted admixture measures of coniferous species, an increase in SOC stocks in beech forests can be achieved as part of the necessary adaptation of beech forests to climate change.


2016 ◽  
Vol 25 (10) ◽  
pp. 1110 ◽  
Author(s):  
Dong-Gill Kim ◽  
Habitamu Taddese ◽  
Abrham Belay ◽  
Randy Kolka

We conducted studies to assess the impact of traditional fire management on soil organic carbon and total nitrogen pools. We compared organic carbon and total nitrogen pools in forest floor and mineral soil (0–100-cm depth) in three areas burned by local communities (B) with adjacent unburned areas (UB) (three paired sites; 1, 5 and 9 years since fire; hereafter B1-UB, B5-UB and B9-UB) in a montane forest in southern Ethiopia. Despite differences in time since fire and dominant post-fire vegetation, forest floor and mineral soil organic carbon and total nitrogen concentrations and pools were not significantly different between burned and unburned pairs or across sites. However, mineral soil carbon : nitrogen ratio was significantly higher in the burned area of B9-UB (0–10 cm) and B5-UB (10–20 cm), indicating small losses of nitrogen relative to carbon, likely from plant uptake or possibly leaching of nitrogen post fire. Combined, the data suggest that traditional fire management did not dramatically affect forest floor and mineral soil organic carbon and total nitrogen dynamics at these sites.


Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1562
Author(s):  
Iveta Varnagirytė-Kabašinskienė ◽  
Povilas Žemaitis ◽  
Kęstutis Armolaitis ◽  
Vidas Stakėnas ◽  
Gintautas Urbaitis

In the context of the specificity of soil organic carbon (SOC) storage in afforested land, nutrient-poor Arenosols and nutrient-rich Luvisols after afforestation with coniferous and deciduous tree species were studied in comparison to the same soils of croplands and grasslands. This study analysed the changes in SOC stock up to 30 years after afforestation of agricultural land in Lithuania, representing the cool temperate moist climate region of Europe. The SOC stocks were evaluated by applying the paired-site design. The mean mass and SOC stocks of the forest floor in afforested Arenosols increased more than in Luvisols. Almost twice as much forest floor mass was observed in coniferous than in deciduous stands 2–3 decades after afforestation. The mean bulk density of fine (<2 mm) soil in the 0–30 cm mineral topsoil layer of croplands was higher than in afforested sites and grasslands. The clear decreasing trend in mean bulk density due to forest stand age with the lowest values in the 21–30-year-old stands was found in afforested Luvisols. In contrast, the SOC concentrations in the 0–30 cm mineral topsoil layer, especially in Luvisols afforested with coniferous species, showed an increasing trend due to the influence of stand age. The mean SOC values in the 0–30 cm mineral topsoil layer of Arenosols and Luvisols during the 30 years after afforestation did not significantly differ from the adjacent croplands or grasslands. The mean SOC stock slightly increased with the forest stand age in Luvisols; however, the highest mean SOC stock was detected in the grasslands. In the Arenosols, there was higher SOC accumulation in the forest floor with increasing stand age than in the Luvisols, while the proportion of SOC stocks in mineral topsoil layers was similar and more comparable to grasslands. These findings suggest encouragement of afforestation of former agricultural land under the current climate and soil characteristics in the region, but the conversion of perennial grasslands to forest land should be done with caution.


2015 ◽  
Vol 2 (2) ◽  
pp. 871-902 ◽  
Author(s):  
H. C. Hombegowda ◽  
O. van Straaten ◽  
M. Köhler ◽  
D. Hölscher

Abstract. Tropical agroforestry has an enormous potential to sequester carbon while simultaneously producing agricultural yields and tree products. The amount of soil organic carbon (SOC) sequestered is however influenced by the type of the agroforestry system established, the soil and climatic conditions and management. In this regional scale study, we utilized a chronosequence approach to investigate how SOC stocks changed when the original forests are converted to agriculture, and then subsequently to four different agroforestry systems (AFSs): homegarden, coffee, coconut and mango. In total we established 224 plots in 56 plot clusters across four climate zones in southern India. Each plot cluster consisted of four plots: a natural forest reference plot, an agriculture reference and two of the same AFS types of two ages (30–60 years and > 60 years). The conversion of forest to agriculture resulted in a large loss the original SOC stock (50–61 %) in the top meter of soil depending on the climate zone. The establishment of homegarden and coffee AFSs on agriculture land caused SOC stocks to rebound to near forest levels, while in mango and coconut AFSs the SOC stock increased only slightly above the agriculture stock. The most important variable regulating SOC stocks and its changes was tree basal area, possibly indicative of organic matter inputs. Furthermore, climatic variables such as temperature and precipitation, and soil variables such as clay fraction and soil pH were likewise all important regulators of SOC and SOC stock changes. Lastly, we found a strong correlation between tree species diversity in homegarden and coffee AFSs and SOC stocks, highlighting possibilities to increase carbon stocks by proper tree species assemblies.


2021 ◽  
Vol 4 ◽  
Author(s):  
Ellen Desie ◽  
Bart Muys ◽  
Boris Jansen ◽  
Lars Vesterdal ◽  
Karen Vancampenhout

Despite the general agreement that maximizing carbon storage and its persistence in forest soils are top priorities in the context of climate change mitigation, our knowledge on how to steer soil organic carbon (SOC) through forest management remains limited. For some soils, tree species selection based on litter quality has been shown a powerful measure to boost SOC stocks and stability, whereas on other locations similar efforts result in insignificant or even opposite effects. A better understanding of which mechanisms underpin such context-dependency is needed in order to focus and prioritize management efforts for carbon sequestration. Here we discuss the key role of acid buffering mechanisms in belowground ecosystem functioning and how threshold behavior in soil pH mediates tree species effects on carbon cycling. For most forests around the world, the threshold between the exchange buffer and the aluminum buffer around a pH-H2O of 4.5 is of particular relevance. When a shift between these buffer domains occurs, it triggers changes in multiple compartments in the soil, ultimately altering the way carbon is incorporated and transformed. Moreover, the impact of such a shift can be amplified by feedback loops between tree species, soil biota and cation exchange capacity (CEC). Hence, taking into account non-linearities related to acidity will allow more accurate predictions on the size and direction of the effect of litter quality changes on the way soil organic carbon is stored in forest soils. Consequently, this will allow developing more efficient, context-explicit management strategies to optimize SOC stocks and their stability.


Author(s):  
Christina Steffens ◽  
Christian Beer ◽  
Stephanie Schelfhout ◽  
An De Schrijver ◽  
Eva‐Maria Pfeiffer ◽  
...  

2020 ◽  
Author(s):  
Axel Don ◽  
Christina Hagen ◽  
Erik Grüneberg ◽  
Cora Vos

&lt;p&gt;Soil disturbance and disruption is assumed to enhance mineralisation and cause losses of soil organic carbon. Therefore, no tillage is promoted as soil carbon sequestration measure. However, the experimental evidence of enhanced carbon turnover due to soil disturbance is rare.&amp;#160; We investigated soil disturbance in forest ecosystems with simulated bioturbation of wild boar. Wild boar are effective at mixing and grubbing in the soil and wild boar populations are increasing dramatically in many parts of the world. In a six-year field study, we investigated the effect of wild boar bioturbation on the stocks and stability of soil organic carbon in two forest areas at 23 plots. The organic layer and mineral soil down to 15 cm depth were sampled in the disturbed plots and adjacent undisturbed reference plots.&lt;/p&gt;&lt;p&gt;No significant changes in soil organic carbon stocks were detected in the bioturbation plots compared with non-disturbed reference plots. However, around 50% of forest floor carbon was transferred with bioturbation to mineral soil carbon and the stock of stabilised mineral-associated carbon increased by 28%. Thus, a large proportion of the labile carbon in the forest floor was transformed into more stable carbon. Carbon saturation of mineral surfaces was not detected, but carbon loading per unit mineral surface increased by on average 66% due to bioturbation. This indicates that mineral forest soils have non-used capacity to stabilise and store more carbon.&lt;/p&gt;&lt;p&gt;Our results indicate that soil disturbance and bioturbation alone does not affect soil carbon turnover and stocks, but only change the distribution of carbon in the soil profile. This is in line with results from no-tillage experiments. The prevailing effect is a redistribution of carbon in the soil profile with no changes in total soil carbon stocks. We discuss these findings in the light of soils as potential sinks for carbon.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;


2019 ◽  
Author(s):  
Axel Don ◽  
Christina Hagen ◽  
Erik Grüneberg ◽  
Cora Vos

Abstract. Most forest soils are characterised by a steep carbon gradient from the forest floor to the mineral soil, indicating that carbon is prevented from entry into the soil. Bioturbation can help incorporate litter-derived carbon into the mineral soil. Wild boar are effective at mixing and grubbing in the soil and wild boar populations are increasing in many parts of the world. In a six-year field study, we investigated the effect of wild boar bioturbation on the stocks and stability of soil organic carbon in two forest areas. Regular bioturbation mimicking grubbing by wild boar was performed artificially in 23 plots and the organic layer and mineral soil down to 15 cm depth were then sampled. No significant changes in soil organic carbon stocks were detected in the bioturbation plots compared with non-disturbed reference plots. However, around 50 % of forest floor carbon was transferred with bioturbation to mineral soil carbon and the stock of stabilised mineral-associated carbon increased by 28 %. Thus, a large proportion of the labile carbon in the forest floor was transformed into more stable carbon. Carbon saturation of mineral surfaces was not detected, but carbon loading per unit mineral surface increased by on average 66 % in the forest floor due to bioturbation. This indicates that mineral forest soils have non-used capacity to stabilise and store carbon. Transfer of aboveground litter into the mineral soil is the only rate-limiting process. Wild boar can help to speed up this process with their grubbing activity.


2019 ◽  
Author(s):  
Ping P Zhang ◽  
Yan L Zhang ◽  
Jun C Jia ◽  
Yong X Cui ◽  
Xia Wang ◽  
...  

Selecting optimal revegetation patterns, i.e., patterns that are more effective for soil organic carbon (SOC) and total nitrogen (TN) accumulation is particularly important for mine land reclamation. However, there have been few evaluations of the effects of different revegetation patterns on the SOC and TN in reclaimed mine soils on the Loess Plateau, China. In this study, the SOC and TN stocks were investigated at reclaimed mine sites (RMSs), including artificially revegetated sites (ARSs) (arbors [Ar], bushes [Bu], arbor-bush mixtures [AB], and grasslands [Gr]) and a natural recovery site (NRS), as well as at undisturbed native sites (UNSs). Overall, the SOC and TN stocks in the RMSs were lower than those in the UNSs over 10–13 years after reclamation. Except for those in Ar, the SOC and TN stocks in the ARSs were significantly larger than those in the NRS. Compared with those in the NRS, the total SOC stocks in the 100 cm soil interval increased by 51.4%, 59.9%, and 109.9% for Bu, AB, and Gr, respectively, and the TN stocks increased by 33.1%, 35.1%, and 57.9%. The SOC stocks in the 0 – 100 cm soil interval decreased in the order of Gr (3.78 kg m –2) > AB (2.88 kg m–2) ≥ Bu (2.72 kg m–2), and the TN stocks exhibited a similar trend. These results suggest that grasslands were more favorable than woodlands for SOC and TN accumulation in this arid area, especially in Ar. Thus, in terms of the accumulation of SOC and TN, grassland planting is recommended as a revegetation pattern for areas with reclaimed mine soils.


2020 ◽  
Author(s):  
Zhenhui Jiang ◽  
Anna Gunina ◽  
Lucas Merz ◽  
Yihe Yang ◽  
Yakov Kuzyakov ◽  
...  

&lt;p&gt;Afforestation with pure and mixed-species is an important strategy to improve soil organic carbon (SOC) stocks and restore degraded lands. However, what remains unclear is the stability of SOC to microbial degradation after afforestation and the effect of tree species composition. Moreover, it is important to reveal how sensitive the SOC in afforestation lands is to environmental changes, such as warming. To study the combined effects of warming and the tree species composition on decomposition of SOC by microorganisms and enzyme activities, soils were collected from the monocultural and mixtures of Silver birch (Betula Pendula) and European beech (Fagus Silvatica) (BangorDiversity, UK, 12 years since afforestation) and were incubated for 169 days at 0, 10, 20, 30 &amp;#176;C at 60 % of WHC. The field experiment is arranged into a completely randomized design with n=4. The CO&lt;sub&gt;2&lt;/sub&gt; efflux was measured constantly, whereas activities of &amp;#946;-glucosidase, chitinase and acid phosphatase, and content of microbial biomass C (MBC) were obtained at the end of the incubation.&amp;#160;Results showed that soil cumulative CO&lt;sub&gt;2&lt;/sub&gt; efflux increased by 34.7&amp;#8211;107% with the temperature. Potential enzyme activities were dependent on tree species composition. Warming, but not tree species exhibited a significant impact on the temperature sensitivity (Q10) of soil cumulative CO&lt;sub&gt;2&lt;/sub&gt; efflux and enzyme activities. The greatest temperature sensitivity (Q&lt;sub&gt;10&lt;/sub&gt;) of total CO&lt;sub&gt;2&lt;/sub&gt; efflux was found at 10&amp;#8211;20 &amp;#176;C and was 2.0&amp;#8211;2.1, but that of enzyme activities were found as 0.9&amp;#8211;1.1 at 0&amp;#8211;10 &amp;#176;C. These results suggest that warming has an asynchronous effect on the SOC decomposition and enzyme activity, and enzymes cannot account for the temperature sensitivity of soil respiration. Thus, thermal adaptations of SOC mineralization is independent of the adaptation of the enzyme pool.&lt;/p&gt;


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