Belowground Litter Research Articles

Accurate representation of leaf longevity is important for simulating ecosystem carbon cycle

Leaf longevity and leaf turnover rate are important plant traits relating to plant growth, leaf photosynthesis and respiration, plant canopy dynamic and many other factors, but dynamic global vegetation models only set inaccurate values for these factors. In this study, we firstly investigated the leaf longevities at major vegetation types based on 418 field measurements from around the world. By replacing the default leaf longevities in the Lund-Potsdam-Jena model (LPJ) with the revised values, we examined the changes in simulated carbon cycle caused by the revised parameters. The results suggested that the compiled observations of leaf longevity were significantly different from the default values in LPJ. Both the vegetation production and respiration of the simulated natural ecosystems showed significant changes based on the revised leaf longevity compared with the predictions developed using default model parameters. Of all of the variables, the aboveground and belowground litter pools showed the largest changes (about 10% globally). Globally, the default parameters induced a significant overestimation of terrestrial carbon sink by 3%, compared with a simulation using the revised parameters. Furthermore, the uncertainties in leaf longevity caused various uncertainties (5–30%) in the simulated carbon fluxes and carbon pools. The offset of biases in intermediate variables might result in rational final model outputs. Overall, more accurate leaf longevities are critical for simulating the vegetation distribution and ecosystem carbon cycle.

Disentangling the Litter Quality and Soil Microbial Contribution to Leaf and Fine Root Litter Decomposition Responses to Reduced Rainfall

Climate change-induced rainfall reductions in Mediterranean forests negatively affect the decomposition of plant litter through decreased soil moisture. However, the indirect effects of reduced precipitation on litter decomposition through changes in litter quality and soil microbial communities are poorly studied. This is especially the case for fine root litter, which contributes importantly to forests plant biomass. Here we analyzed the effects of long-term (11 years) rainfall exclusion (29% reduction) on leaf and fine root litter quality, soil microbial biomass, and microbial community-level physiological profiles in a Mediterranean holm oak forest. Additionally, we reciprocally transplanted soils and litter among the control and reduced rainfall treatments in the laboratory, and analyzed litter decomposition and its responses to a simulated extreme drought event. The decreased soil microbial biomass and altered physiological profiles with reduced rainfall promoted lower fine root—but not leaf—litter decomposition. Both leaf and root litter, from the reduced rainfall treatment, decomposed faster than those from the control treatment. The impact of the extreme drought event on fine root litter decomposition was higher in soils from the control treatment compared to soils subjected to long-term rainfall exclusion. Our results suggest contrasting mechanisms driving drought indirect effects on above-(for example, changes in litter quality) and belowground (for example, shifts in soil microbial community) litter decomposition, even within a single tree species. Quantifying the contribution of these mechanisms relative to the direct soil moisture-effect is critical for an accurate integration of litter decomposition into ecosystem carbon dynamics in Mediterranean forests under climate change.

Root rather than leaf litter input drives soil carbon sequestration after afforestation on a marginal cropland

Afforestation on croplands has been proposed as a means to mitigate the increasing emission of anthropogenic CO2. However, the relative contribution of above- and belowground litter input on soil organic carbon (SOC) sequestration following afforestation is not fully understood. We used a 270-day laboratory incubation experiment to examine the impact of litter type (i.e., leaf vs. fine root litter) of a poplar tree (Populus simonii Carr., C3 plant) on soil respiration and the turnover of new vs. old soil C in surface (0–10cm) and subsurface mineral soils (40–50cm) collected from a marginal cropland planted to maize (Zea mays L., C4 plant) in a semi-arid region in northeast China. Our results showed that fine root rather than leaf litter addition helps to sequester SOC even though soil microbial respiration rates were stimulated by both leaf and fine root litter input. Neither leaf nor fine root litter addition stimulated mineralization of old soil C across the two soil layers, but more new C was incorporated into the soil with fine root addition as compared with leaf litter addition. Moreover, the subsurface soil had greater potential to sequester SOC as compared to the surface soil. Our results suggest that root rather than leaf litter input drives soil carbon sequestration on the marginal soil, especially in the subsurface soil, and planting deep-rooted trees with large belowground biomass production could be used to increase SOC sequestration in marginal croplands.

Tree species’ influences on soil carbon dynamics revealed with natural abundance 13C techniques

Background and aims The carbon (C) sequestration potential of land-use practices is increasingly important. Trees sequester atmospheric C into biomass and above and belowground litter but may also prime the decomposition of soil organic matter (SOM). We compared the influence of Acer pseudoplatanus (Sycamore) and Larix x. europlepsis (Hybrid Larch) on soil C decomposition.

Radiocarbon-Based Assessment of Heterotrophic Soil Respiration in Two Mediterranean Forests

The amount of soil organic carbon (SOC) released into the atmosphere as carbon dioxide (CO2), which is referred to as heterotrophic respiration (Rh), is technically difficult to measure despite its necessity to the understanding of how to protect and increase soil carbon stocks. Within this context, the aim of this study is to determine Rh in two Mediterranean forests dominated by pine and oak using radiocarbon measurements of the bulk SOC from different soil layers. The annual Rh was 3.22 Mg C ha−1 y−1 under pine and 3.13 Mg C ha−1 y−1 under oak, corresponding to 38 and 31% of the annual soil respiration, respectively. The accuracy of the Rh values was evaluated by determining the net primary production (NPP), as the sum of the Rh and the net ecosystem production measured by eddy covariance, then comparing it with the NPP obtained through independent biometric measurements. No significant differences were observed, which suggested the suitability of our methodology to infer Rh. Assuming the C inputs to soil to consist exclusively of the aboveground and belowground litter and the C output exclusively of the Rh, both soils were C sinks, which is consistent with a previous modeling study that was performed in the same stands. In conclusion, radiocarbon analysis of bulk SOC provided a reliable estimate of the average annual amount of soil carbon released to the atmosphere; hence, its application is convenient for calculating Rh because it utilizes only a single soil sampling and no time-consuming monitoring activities.

Effects of land use and precipitation on above- and below-ground litter decomposition in a semi-arid temperate steppe in Inner Mongolia, China

Land use greatly affects litter production, quality, and decomposition rates, and therefore alters the soil carbon stocks and influences ecosystem carbon cycling. In this study, our aims were to investigate the effects of land use (grazing, mowing, and grazing exclusion), litter types, and precipitation on litter production, decomposition processes, and soil carbon stocks. Litter inputs, quality, and decomposition rates were significantly influenced by land use and differed greatly between 2011 (a dry year) and 2012 (a moist year). Above-ground litter production in 2012 ranged from 165 to 180gm−2, versus from 50 to 73gm−2 in 2011; below-ground litter production in 2012 was 1.9 to 6.0 times that in 2011. Decomposition rates of above-ground litter (ka) were greater than those of below-ground litter (kb). The ka in 2012 was 1.9 to 2.8 times those in 2011 and kb in 2012 was 6.5 to 10.8 times those in 2011. The ka was strongly positively correlated with the N content (R2=0.713) and strongly negatively correlated with the C/N ratio (R2=0.585), whereas kb was explained best by the C/N ratio. Precipitation was a main factor that controlled ecosystem C cycling processes, and increased litter decomposition increased soil carbon stocks. Land use therefore played an important role in litter input and decomposition processes and in carbon sequestration, but these processes responded to the initial litter quality and precipitation.

Macrophyte root and rhizome decay: the impact of nutrient enrichment and the use of live versus dead tissue in decomposition studies

The decomposition of roots and rhizomes of two macrophytes, Eleocharis cellulosa and Typha domingensis, was studied in oligotrophic phosphorus (P) limited marshes of northern Belize. The experiment was conducted in long-term control and P enriched plots in five limestone-based inland marshes. Decomposition of naturally senescent root and rhizome litter was studied over 9 months using litterbags. Belowground litter was acquired by growing plants in unenriched (control) or P enriched marsh soils for 5 months. Plants were then allowed to naturally senesce using a split root design, which promoted nutrient retranslocation. The resulting senescent litter had 30 % higher C:P and 40 % lower P content than living roots and rhizomes. There were no differences in C:N among treatments or senescent versus live litter. Litterbags, filled with control or enriched root and rhizome litter, were buried in the upper 10–14 cm soil in the corresponding plot of each marsh. Differences in the rate of decay between species were greatest for rhizome tissue, with Typha decaying more than twice as fast as Eleocharis. For both species, however, tissue P enrichment had no effect on coarse root and rhizome decay. Enhanced root production from P enrichment, coupled with no change in decay, should lead to enhanced accretion over time. Additional tests, using litterbags filled with living roots and rhizomes, yielded dramatically different results between treatments compared to senescent tissue. Results from senescent belowground tissue also differed from shoot decomposition. Caution should be exercised when inferring belowground decomposition from live tissue and aboveground rates of decay.

Carbon budgets in fertile silver birch (Betula pendula Roth) chronosequence stands

Carbon (C) budgets were compiled for silver birch chronosequence stands by synthesizing the above- and belowground C pools and fluxes with the aim to assess the impact of age on stand C sequestration and cycling.The fine root (d<2mm) biomass, production, turnover rate and longevity of 13-, 32- and 45-year-old silver birch stands were determined by the ingrowth core method. Fine root production after the third year from the installation of cores was 0.89, 1.44 and 1.31tha−1year−1 in the pole, middle-aged and premature silver birch stands, respectively.Soil respiration (Rs) was measured during the two growing seasons of 2010 and 2011; the trenching method was used to estimate the contribution of heterotrophic respiration (Rh) to total soil respiration. Soil temperature was the driving environmental factor of the temporal variation of Rs and Rh. Stand age affected significantly respiration rates. Annual Rs was 6.2, 9.7 and 8.2tCha−1 and annual Rh was 2.97, 4.21 and 3.61tCha−1 in the pole, middle-aged and premature silver birch stands, respectively. The annual contribution of Rh to Rs was similar in each stand ranging from 0.43 to 0.48.Total annual net primary production (NPP) of the ecosystems of 7.4, 7.9 and 8.5tCha−1year−1 was estimated in the pole, middle-aged and premature stands. After balancing the C input and output fluxes in the silver birch stands of different development stages, it appeared that they all acted as effective C sinks. Net ecosystem production (NEP) was 4.4, 3.7 and 4.9tCha−1year−1 in the pole, middle-aged and premature stands, respectively. In the premature stand the second layer of the spruce contributed significantly to the increased C input. The annual organic C input into the soil through above- and belowground litter occurred to be of the same magnitude as C loss via annual heterotrophic respiration. Thus, annual increment of woody biomass in fertile silver birch stands reflects annual organic C sequestration in the ecosystem. Among the studied stands, estimated NEP values were the lowest in the middle-aged stand and the highest in the oldest stand, indicating non-linear relationship between stand NEP and stand age.

Influence of temperature and organic matter content on soil respiration in a deciduous oak forest

The increasing temperature enhances soil respiration differently depend on different conditions (soil moisture, soil organic matter, the activity of soil microbes). It is an essential factor to predicting the effect of climate change on soil respiration. In a temperate deciduous forest (North-Hungary) we added or removal aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO 2 efflux, soil moisture and soil temperature. Soil CO 2 efflux was measured at each plot using chamber based soil respiration measurements. We determined the temperature sensitivity of soil respiration. The effect of doubled litter was less than the effect of removal. We found that temperature was more influential in the control of soil respiration than soil moisture in litter removal treatments, particularly in the wetter root exclusion treatments (NR and NI) (R 2 : 0.49-0.61). Soil moisture (R 2 : 0.18-0.24) and temperature (R 2 : 0.18-0.20) influenced soil respiration similarly in treatments, where soil was drier (Control, Double Litter, Double Wood). A significantly greater increase in temperature induced higher soil respiration were significantly higher (2-2.5-fold) in root exclusion treatments, where soil was wetter throughout the year, than in control and litter addition treatments. The highest bacterial and fungal count was at the DL treatment but the differences is not significant compared to the Control. The bacterial number at the No Litter, No Root, No Input treatment was significantly lower at the Control. Similar phenomenon can be observed at the fungal too, but the differences are not significant. The results of soil respiration suggest that the soil aridity can reduce soil respiration increases with the temperature increase. Soil bacterial and fungal count results show the higher organic matter content and soil surface cover litter favors the activity.

Fine root longevity and carbon input into soil from below- and aboveground litter in climatically contrasting forests

The major part of carbon (C) flow into forest soil consists of continually renewed fine roots and aboveground litterfall. We studied the belowground C input from the fine root litter of trees and understorey vegetation in relation to their aboveground litterfall in two Norway spruce (Picea abies L.) stands located in northern and southern Finland. The production of fine roots was estimated by using turnover and biomass data from minirhizotrons and soil cores. The foliage litter production of trees was estimated from litter traps, and that of the understorey vegetation from its annual growth and coverage. Finally, we augmented the data with four spruce plots in Sweden in order to study the above- and belowground litter ratios along latitudinal and soil fertility gradients.The fine root biomass of spruce trees per stand basal area was almost double in the northern site compared to the southern site. Furthermore, spruce fine roots in the north persisted significantly longer (97±2weeks) than spruce roots in the south (89±2weeks) or understorey fine roots at both sites. The annual production of tree foliage litter was higher in the southern stand, but the total amount of litter (including trees and understorey, above- and belowground) was similar at both sites, as was the ratio between the above- and belowground litter production.The role of understorey vegetation was greater in the northern site where it was responsible for 23% and 33% of below- and aboveground litter production, respectively, compared to 11% and 15% in the south. Thus, both below- and aboveground understorey C input is substantial and should be taken into account in ecosystem C cycle models.The regression between the aboveground:belowground litter production-ratio and the C:N-ratio of the organic layer (combined data from Finland and Sweden), showed that the share of belowground litter production increased when site fertility decreased. This shift in the litter production pattern from above- to belowground in the least fertile sites may have an impact on litter C quality and soil C storage.

Soil CO2 balance and its uncertainty in forestry-drained peatlands in Finland

To understand the global carbon cycle and the impact of human activity on climate, it is necessary to quantify the net CO2 exchange of ecosystems in different land uses on a large scale. Methods to estimate soil net CO2 exchange (NECO2soil) for drained peatland forests have been largely based on chamber measurements and statistical models. The uncertainty in these methods has not been assessed. Yet, disturbed organic soils are a globally important, potential CO2 source due to their vast carbon storage and its sensitivity to changes in soil moisture.In this study, we estimated the countrywide NECO2soil for the 4.76 million ha of forestry-drained peat soils in Finland. We gathered available litter production and CO2 efflux data and constructed models to be used for the upscaling of NECO2soil from forest inventory data. The contribution of each model and the inventory sampling to the precision of the countrywide estimate was calculated. Also, the sensitivity to possible bias in selected model components was estimated.Compared to the estimated mean NECO2soil, ranging from a source of +20gm−2year−1 of C to a sink of −40gm−2year−1 of C, the uncertainty was high. The precision of the estimate (±1 standard deviation) was ±20gm−2year−1 of C. Due to possible bias in the estimated belowground litter input, the overall uncertainty was much higher, around ±60gm−2year−1 of C.The main reason for the high relative uncertainty was NECO2soil being on average close to zero in these boreal forestry-drained peatlands. Forest inventory sample size was large enough and the data for the models were mainly sufficient. To reduce the uncertainty, better understanding of belowground carbon fluxes in order to accurately determine the C input to soil, is crucial.

Norway spruce fine root dynamics and carbon input into soil in relation to environmental factors

Knowledge of the quantity of belowground litter carbon (C) input is scarce but highly valued in C budget calculations. Specifically, the turnover rate of fine roots is considered as one of the most important parameters in the estimation of changes in soil C stock. In this thesis Norway spruce (Picea abies L. (Karst.)) fine root lifespan and litter production were studied and their responses to nutrient availability and temperature were examined. Aboveground foliage and understory litter C inputs were also quantified. Furthermore, fine root isotopic C ages were compared to fine root lifespans. Increased nutrient availability and higher temperature shortened spruce fine root lifespan both in the manipulation treatments and along a latitude gradient. Fertilization improved tree growth and the absolute amount of litter production, both belowand aboveground. Soil warming, by contrast, increased the belowground litter production in relation to aboveground foliage litterfall but did not lead to long-term increases in aboveground tree growth. In warmed soil, the changes in spruce short root morphology indicated nutrient deficiency. The results indicated that in nutrient limited forests climate warming is unlikely to increase the aboveground tree growth in the long-term. Fine root litter C input into the soil in relation to the aboveground litter C input was higher towards lower fertility, due particularly to the greater contribution of understory vegetation. The structural 14 C age of fine roots was consistently 3 6 years older than fine root lifespan determined with the minirhizotron method indicating that root growth may use also use stored or recycled C. In almost all stands, fine root litter C input into the soil at least equalled the aboveground input, which confirms the significance of belowground litter production in the boreal forest C cycle. The importance of understory vegetation was also significant. In addition on understory vegetation, different stand age and tree species, more studies should also focus on the shift in the litter production pattern from aboveto belowground along environmental change as this may have an impact on litter C quality and soil C storage in boreal forest soils.

中亚热带木本植物各器官凋落物分解特性

中亚热带木本植物各器官凋落物分解特性

Litter Input Controls on Soil Carbon in a Temperate Deciduous Forest

Above‐ and belowground litter inputs in a temperate deciduous forest were altered for 20 yr to determine the importance of leaves and roots on soil C and soil organic matter (SOM) quantity and quality. Carbon and SOM quantity and quality were measured in the O horizon and mineral soil to 50 cm in five treatments (control, double litter [DL], no litter [NL], no roots [NR], no inputs [NI]). After two decades of doubled litter addition, soil C and SOM did not increase. However, leaf litter exclusions reduced soil C (O and mineral horizons combined) by 24% in NL and 33% in NI treatments. In the mineral soil, the largest declines occurred in the 0‐ to 10‐cm depth (0.93–2.01 kg C m−2), although losses were observed throughout the entire solum. The NR treatments showed no losses of C. Thermal characterization of SOM quality differed among treatments in the 0‐ to 10‐cm depth. Patterns of CO2evolution during SOM combustion revealed differences in SOM quality between surface and deeper horizons. Our work shows that the sources of litter are important in controlling soil C. Leaf litter made important contributions to maintaining current stocks of soil C; increased leaf litter did not increase soil C, but decreases in litter inputs resulted in rapid soil C declines. Root litter may ultimately provide more stable sources of soil C. Management activities or environmental alterations that decrease litter inputs in mature forests can lower soil C content; however, increases in forest productivity and the resulting increased litter production seem unlikely to increase soil C sequestration.

Litter and Root Manipulations Provide Insights into Soil Organic Matter Dynamics and Stability

Understanding controls on C stored in soil organic matter (SOM) is of critical importance to models of biospheric C sequestration. Although ecosystem C models assume a strong relationship between plant litter inputs and soil C accumulation, there is little experimental evidence to support this assumption. The Detritus Input and Removal Treatments (DIRT) experiment at Harvard Forest was designed to assess how rates and sources of plant litter inputs control the accumulation and dynamics of organic matter in soils across decadal time scales. Carbon and SOM quantity and quality were measured in O horizon and mineral soil in five treatments: control, double litter, no litter, no roots, and no inputs. After 20 yr of manipulation, doubling litter inputs did not increase bulk soil C or N content, light or heavy fraction pools of C, or measures of labile C. However, the activities of two key enzymes (β‐glucosidase and phosphomonoesterase) increased 30% with litter additions. Exclusion of either aboveground litter or root inputs resulted in sharp declines in O‐horizon C and N but smaller decreases in total mineral soil C and N. However, decreases in light fraction C and soil respiration were significant in removal treatments. Litter exclusion resulted in an 18% decline in total profile mineral soil C, whereas root exclusion resulted in a 9% decline, indicating the importance of aboveground inputs to long‐term C pools. Soil C pools in this forest do not respond linearly or immediately to aboveground or belowground litter inputs, and thus efforts to sequester C by managing productivity and associated litter inputs will probably not result in increased C storage in short time frames.

Decomposition of aboveground and root litter for three desert herbs: mass loss and dynamics of mineral nutrients

Litter decomposition is an important process in terrestrial C and N cycling, but it is still unclear which factors are controlling litter decomposition and nutrient release in arid and semiarid environments. Litterbag experiment was carried out to evaluate the mass loss and nutrient dynamics of aboveground and belowground litter of three desert plants with different life form (ephemeral herbs and perennials). The decomposition rates of Erodium oxyrrhynchum and Eremurus inderiensis (ephemeral herbs) were faster than that of Seriphidium santolinum (perennial) after 2 years. The content of neutral soluble detergent positively correlated with mass loss and was responsible for the faster rates in the primary decomposition phase. Additionally, differences in mass loss and N release between aboveground and belowground litter depended on litter type. Decomposition of the aboveground litter was mainly affected by initial nutrient content and C component of litter, whereas root decomposition was primarily determined by the content of recalcitrant compounds of litter. Only stem generally exhibited N accumulation, whereas there was no relationship between the initial N content and net N immobilization during decomposition of leaf and root litter. Our results suggest that the decomposition rate and nutrient release in temperate desert are closely linked to initial nutrients and C contents of litters, and decomposition of desert litters depended on plant life form.

Effects of belowground litter addition, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

Abstract. Soil carbon (C) and nitrogen (N) cycling are sensitive to changes in environmental factors and play critical roles in the responses of terrestrial ecosystems to natural and anthropogenic perturbations. This study was conducted to quantify the effects of belowground particulate litter (BPL) addition, increased precipitation and their interactions on soil C and N mineralization in two adjacent sites where belowground photosynthate allocation was manipulated through vegetation clipping in a temperate steppe of northeastern China from 2010 to 2011. The results show that BPL addition significantly increase soil C mineralization rate (CMR) and net N mineralization rate (NMR). Although increased precipitation-induced enhancement of soil CMR essentially ceased after the first year, stimulation of soil NMR and net nitrification rate continued into the second year. Clipping only marginally decreased soil CMR and NMR during the two years. There were significant synergistic interactions between BPL addition (and increased precipitation) and clipping on soil CMR and NMR, likely to reflect shifts in soil microbial community structure and a decrease in arbuscular mycorrhizal fungi biomass due to the reduction of belowground photosynthate allocation. These results highlight the importance of plants in mediating the responses of soil C and N mineralization to potentially increased BPL and precipitation by controlling belowground photosynthate allocation in the temperate steppe.

Fine root turnover and litter production of Norway spruce in a long-term temperature and nutrient manipulation experiment

Increased soil temperature and nutrient availability enhance soil biological activity. We studied how these affect fine root growth and survival, i.e. below-ground litter production, in relation to above-ground foliage litter production of Norway spruce (Picea abies (L.) Karst.). The treatments, irrigation (I), soil warming + irrigation (WI), fertilization + irrigation (FI) and soil warming + fertilization + irrigation (WFI) were started in 1987 (F, I) and in 1995 (W). The annual production of fine root litter was estimated from minirhizotrons (survival) and soil-cores (biomass) and the annual above-ground litter production from litter traps. The number and elongation of fine roots tended to be higher in WI and I compared to the other treatments, which may indicate nutrient shortage. Fine roots in the WFI treatment had the lowest median longevity and from three to fourfold higher below-ground litter production compared to WI, FI or I - higher soil temperature increased the litter input particularly into the mineral soil. Only fertilization increased the above-ground litter production. As warmer and more nutrient-rich soil significantly shortened the fine root lifespan and increased the litter input, the storage of carbon in boreal forest soil may increase in the future.

Microbial community diversity in a 21-year-old temperate alley cropping system

Soil physical and chemical properties in the crop alleys and tree rows in alley cropping systems vary greatly due to differences in litter quality and microclimate under trees compared to the alleys. Variations in soil properties influence microbial diversity and function, and thus, in alley cropping systems, bacterial diversity could be different between soils in tree rows and crop alleys. The objective of this study was to compare and contrast soil bacterial diversity in the crop alleys and tree rows in a 21-year-old alley cropping system in Northeast Missouri, USA. Soil samples were taken in three parallel transects to a depth of 10 cm in the tree row and at the middle of the alley in a silver maple (Acer saccharinum) alley cropping system with a companion maize (Zea mays)—soybean (Glycine max) rotation. Soil bulk density, C and N concentrations were similar between the different transects while minor differences were observed between crop alleys and tree rows. No significant difference in bacterial diversity was observed between the tree rows and alley soil based the denaturing gradient gel electrophoresis profiles, band richness (19.6 and 22.8 for tree row and alley, respectively) and Shannon–Weiner diversity (2.958 and 3.099 for tree row and alley, respectively). Identification of bacterial genera revealed dominance of gram +ve as well as gram −ve bacteria in both soil types. Ordination plot revealed no clustering effect based on location (transect) or on the cropping system in the different samples. Bacterial diversity in crop alleys most likely was influenced not only by the maize-soybean rotation, but also by the tree rows contributing both above and belowground litter for the past 21 years.

Simulating the soil carbon dynamics of Pinus densiflora forests in central Korea

We developed a simple forest soil carbon model (Korean Forest Soil Carbon model, KFSC) requiring a small number of parameters to evaluate the forest soil carbon stocks and dynamics. The KFSC was composed of live biomass (BIO), primary dead organic matter (DOM) (AWD: aboveground woody debris; BWD: belowground woody debris; ALT: aboveground litter; and BLT: belowground litter), and secondary DOM (HUM: humus and SOC: soil organic carbon). The KFSC was validated against six Pinus densiflora forests at Gyeonggi province in central Korea and validation results showed that the model predicted the AWD, ALT, and SOC stocks with high precision (r 2=0.90–0.98, slope = 0.95–0.98). We simulated 160 years of carbon dynamics of the P. densiflora forests in Gyeonggi province (11,607 ha) under alternative clear-cut intervals that had been taking place in the past (30, 50, and 80 years). Simulated total SOC stock ranged from 298.7 to 520.5 Gg C depending on the scenario and increased with time in all scenarios. The estimated total SOC stock was higher in the scenario of less frequent clear-cut, while its annual increment was higher in the scenario of more frequent clear-cut in the past. The KFSC will be useful, especially for simulating soil carbon dynamics in forests with scarce information, and has the potential to estimate soil carbon dynamics at a national scale by incorporating with geographical information system.