scholarly journals Higher stand densities can promote soil carbon storage after conversion of temperate mixed natural forests to larch plantations

Author(s):  
Meng Na ◽  
Xiaoyang Sun ◽  
Yandong Zhang ◽  
Zhihu Sun ◽  
Johannes Rousk

AbstractSoil carbon (C) reservoirs held in forests play a significant role in the global C cycle. However, harvesting natural forests tend to lead to soil C loss, which can be countered by the establishment of plantations after clear cutting. Therefore, there is a need to determine how forest management can affect soil C sequestration. The management of stand density could provide an effective tool to control soil C sequestration, yet how stand density influences soil C remains an open question. To address this question, we investigated soil C storage in 8-year pure hybrid larch (Larix spp.) plantations with three densities (2000 trees ha−1, 3300 trees ha−1 and 4400 trees ha−1), established following the harvesting of secondary mixed natural forest. We found that soil C storage increased with higher tree density, which mainly correlated with increases of dissolved organic C as well as litter and root C input. In addition, soil respiration decreased with higher tree density during the most productive periods of warm and moist conditions. The reduced SOM decomposition suggested by lowered respiration was also corroborated with reduced levels of plant litter decomposition. The stimulated inputs and reduced exports of C from the forest floor resulted in a 40% higher soil C stock in high- compared to low-density forests within 8 years after plantation, providing effective advice for forest management to promote soil C sequestration in ecosystems.

Author(s):  
Zhuangzhuang Qian ◽  
Xiaomin Ge ◽  
Yunxia Bai ◽  
Ye Tian ◽  
Shunyao Zhuang ◽  
...  

The main objective of this study was to compare the effects of two densities (278 stems·ha−1 with two spacings of 6 m × 6 m or 4.5 m × 8 m, 400 stems·ha−1 with two spacings of 5 m × 5 m or 3 m × 8 m) and three poplar clones (NL95, NL895, and NL797) on productivity and carbon (C) sequestration of poplar ecosystems. The results showed that planting density significantly affected the biomass of a single tree. The mean tree biomass of clone NL95 was higher in all spacings than that of the other clones, with a significant difference for the 6 m × 6 m spacing. The biomass of poplar trees ranged from 78.9 to 110.3 Mg·ha−1, with the highest tree biomass observed in the square configuration. Soil C concentration (0–100 cm) increased after 12 years of management. Soil C storage ranged from 138.1 to 164.3 Mg C·ha−1, and the highest soil C storage was in the NL797 poplar plantation with 6 m × 6 m spacing. Our results suggested that clones NL95 and NL797 should be chosen for planting, with a planting density of 278 stems·ha−1 and spacing of 6 m × 6 m.


2021 ◽  
Author(s):  
Xiaocong Zhu ◽  
Mingguo Ma ◽  
Ryunosuke Tateno ◽  
Xinhua He ◽  
Weiyu Shi (S85)

Abstract Backgrounds A large-scale ecological restoration project has been initiated since 1990s in southwest China, which is one of the largest areas of rocky desertification globally. However, the different influences and potential mechanisms of vegetation restoration on soil carbon(C) sequestration in karst and non-karst regions are still unclear. Methods Based on field investigation and multi-source data synthesis, the mechanisms of soil C sequestration were investigated to determine the most important variables affecting the rate of soil C change (Rs) in southwest China. Results Our results show significant differences in soil C sequestration between karst and non-karst regions with faster and longer C sequestration in karst regions, where Rs was approximately 31 % higher than in non-karst soils. And temperatures could be the primary factor inhibiting soil C sequestration without precipitation. The total effect of nitrogen (N) on Rs was positive in both karst and non-karst regions. Conclusions Phosphorus was the dominant factor limiting the use of N in karst regions and then resulting in limitation of C sequestration. The results indicated that soil C storage could be led to intensify uneven increases due to combination of karst environment and climate change in southwest China in future.


2012 ◽  
Vol 9 (1) ◽  
pp. 357-386 ◽  
Author(s):  
W. M. A. Sillen ◽  
W. I. J. Dieleman

Abstract. Elevated atmospheric CO2 levels and increasing nitrogen deposition both stimulate plant production in terrestrial ecosystems. Moreover, nitrogen deposition could alleviate an increasing nitrogen limitation experienced by plants exposed to elevated CO2 concentrations. However, an increased rate of C flux through the soil compartment as a consequence of elevated CO2 concentrations has been suggested to limit C sequestration in terrestrial ecosystems, questioning the potential for terrestrial C uptake to mitigate the increasing atmospheric CO2 concentrations. Our study used data from 69 published studies to investigate whether CO2 elevation and/or nitrogen fertilization could induce an increased carbon storage in grasslands, and considered the influence of management practices involving biomass removal or irrigation on the elevated CO2 effects. Our results confirmed a positive effect of elevated CO2 levels and nitrogen fertilization on plant growth, but revealed that N availability is essential for the increased C influx under elevated CO2 to propagate into belowground C pools. However, moderate nutrient additions also promoted decomposition processes in elevated CO2, reducing the potential for increased soil C storage. An important role in the soil carbon response to elevated CO2 was attributed to the root response, since there was a lower potential for increases in soil C content when root biomass was more responsive to CO2 elevation. Future elevated CO2 concentrations and increasing N deposition might thus increase C storage in plant biomass, but the potential for increased soil C storage is limited.


2006 ◽  
Vol 86 (5) ◽  
pp. 779-782 ◽  
Author(s):  
T. Chevallier ◽  
E. Blanchart ◽  
A. Albrecht ◽  
C. Feller ◽  
M. Bernoux

Establishing pasture on cultivated tropical Vertisols can increase soil organic carbon (SOC), but it is not known whether this increase results solely from enhanced inputs or also from suppressed mineralization. We measured CO2 emissions from a Vertisol under market gardening, and under “young” and “old” Digitaria decumbens pastures. Emissions of CO2-C increased in pastures, compared to market gardening, but relative SOC mineralization (CO2-C/SOC) decreased, implying the protection of SOC against mineralization with pasture establishment. Key words: Tropical pasture, carbon fluxes, soil organic carbon, physical protection, C storage


2021 ◽  
Author(s):  
Guillermo Hernandez-Ramirez ◽  
Thomas J. Sauer ◽  
Yury G. Chendev ◽  
Alexander N. Gennadiev

Abstract. Land use conversions can strongly impact soil organic matter (SOM) storage, which creates paramount opportunities for sequestering atmospheric carbon into the soil. It is known that land uses such as annual cropping and afforestation can decrease and increase SOM, respectively; however, the rates of these changes over time remain elusive. This study focused on extracting the kinetics (k) of turnover rates that describe these long-term changes in soil C storage and also quantifying the sources of soil C. We used topsoil organic carbon density and δ13C isotopic composition data from multiple chronosequences and paired sites in Russia and United States. Reconstruction of soil C storage trajectory over 250 years following conversion from native grassland to continual annual cropland revealed a C depletion rate of 0.010 years−1 (first-order k rate constant), which translates into a mean residence time (MRT) of 100 years (R2 ≥ 0.90). Conversely, soil C accretion was observed over 70 years following afforestation of annual croplands at a much faster k rate of 0.055 years−1. The corresponding MRT was only 18 years (R2 = 0.997) after a lag phase of 5 years. Over these 23 years of afforestation, trees contributed 14 Mg C Ha−1 to soil C accrual in the 0 to 15 cm depth increment. This tree-C contribution reached 22 Mg C Ha−1 at 70 years after tree planting. Over these 70 years of afforestation, the proportion of tree-C to whole soil C increased to reach a sizeable 79 %. Furthermore, assuming steady state of soil C in the adjacent croplands, we also estimated that 45 % of the prairie-C existent at time of tree planting was still present in the afforested soils 70 years later. As intrinsic of k modelling, the derived turnover rates that represent soil C changes over time are nonlinear. Soil C changes were much more dynamic during the first decades following a land use conversion than afterwards when the new land use system approached equilibrium. Collectively, results substantiated that C sequestration in afforested lands is a suitable means to proactively mitigate escalating climate change within a typical person's lifetime, as indicated by MRTs of few decades.


2004 ◽  
Vol 34 (7) ◽  
pp. 1538-1542 ◽  
Author(s):  
Heidi Steltzer

Soil carbon (C) and nitrogen (N) pools were measured under the canopy of 29 white spruce (Picea glauca (Moench) Voss) trees and in the surrounding tundra 3 and 6 m away from each tree at three sites of recent forest expansion along the Agashashok River in northwestern Alaska. The aim was to characterize the potential for forest expansion to lead to increased soil C pools across diverse tundra types. Soil C beneath the trees correlated positively with tree age, suggesting that tree establishment has led to C storage in the soils under their canopy at a rate of 18.5 ± 4.6 g C·m–2·year–1. Soil C in the surrounding tundra did not differ from those under the trees and showed no relationship to tree age. This characterization of the soil C pools at the 3-m scale strengthens the assertion that the pattern associated with the trees is an effect of the trees, because tree age cannot explain variation among tundra sampling locations at this scale. Potential mechanisms by which these white spruce trees could increase soil C pools include greater production and lower litter quality.


2012 ◽  
Vol 79 (4) ◽  
pp. 1191-1199 ◽  
Author(s):  
Sarah D. Eisenlord ◽  
Zachary Freedman ◽  
Donald R. Zak ◽  
Kai Xue ◽  
Zhili He ◽  
...  

ABSTRACTFuture rates of anthropogenic N deposition can slow the cycling and enhance the storage of C in forest ecosystems. In a northern hardwood forest ecosystem, experimental N deposition has decreased the extent of forest floor decay, leading to increased soil C storage. To better understand the microbial mechanisms mediating this response, we examined the functional genes derived from communities of actinobacteria and fungi present in the forest floor using GeoChip 4.0, a high-throughput functional-gene microarray. The compositions of functional genes derived from actinobacterial and fungal communities was significantly altered by experimental nitrogen deposition, with more heterogeneity detected in both groups. Experimental N deposition significantly decreased the richness and diversity of genes involved in the depolymerization of starch (∼12%), hemicellulose (∼16%), cellulose (∼16%), chitin (∼15%), and lignin (∼16%). The decrease in richness occurred across all taxonomic groupings detected by the microarray. The compositions of genes encoding oxidoreductases, which plausibly mediate lignin decay, were responsible for much of the observed dissimilarity between actinobacterial communities under ambient and experimental N deposition. This shift in composition and decrease in richness and diversity of genes encoding enzymes that mediate the decay process has occurred in parallel with a reduction in the extent of decay and accumulation of soil organic matter. Our observations indicate that compositional changes in actinobacterial and fungal communities elicited by experimental N deposition have functional implications for the cycling and storage of carbon in forest ecosystems.


2021 ◽  
Author(s):  
Sylvia Vetter ◽  
Michael Martin ◽  
Pete Smith

<p>Reducing greenhouse gas (GHG) emissions in to the atmosphere to limit global warming is the big challenge of the coming decades. The focus lies on negative emission technologies to remove GHGs from the atmosphere from different sectors. Agriculture produces around a quarter of all the anthropogenic GHGs globally (including land use change and afforestation). Reducing these net emissions can be achieved through techniques that increase the soil organic carbon (SOC) stocks. These techniques include improved management practices in agriculture and grassland systems, which increase the organic carbon (C) input or reduce soil disturbances. The C sequestration potential differs among soils depending on climate, soil properties and management, with the highest potential for poor soils (SOC stock farthest from saturation).</p><p>Modelling can be used to estimate the technical potential to sequester C of agricultural land under different mitigation practices for the next decades under different climate scenarios. The ECOSSE model was developed to simulate soil C dynamics and GHG emissions in mineral and organic soils. A spatial version of the model (GlobalECOSSE) was adapted to simulate agricultural soils around the world to calculate the SOC change under changing management and climate.</p><p>Practices like different tillage management, crop rotations and residue incorporation showed regional differences and the importance of adapting mitigation practices under an increased changing climate. A fast adoption of practices that increase SOC has its own challenges, as the potential to sequester C is high until the soil reached a new C equilibrium. Therefore, the potential to use soil C sequestration to reduce overall GHG emissions is limited. The results showed a high potential to sequester C until 2050 but much lower rates in the second half of the century, highlighting the importance of using soil C sequestration in the coming decades to reach net zero by 2050.</p>


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