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1.
Tropical primary rainforests of Africa are an enormous reservoir of carbon (C), most of which, in the common perception, is stored in the biomass. We studied one of these forests, Ankasa, in the south-western part of Ghana, in terms of quantity and 14C activity of soil organic carbon (SOC) to elucidate the little known important role of soil in storing carbon in such biomass-rich environments. The stock of carbon in the mineral soil to a depth of 1 m was measured to be 151?±?20 Mg C ha?1, a similar value in magnitude to the one of the aboveground biomass being 138–170 Mg C ha?1, including live and dead wood. Surface litter C is roughly 10% (15?±?9 Mg C ha?1) of the C in the biomass and soil. The radiocarbon measurements indicate that SOC was significantly affected by “bomb C” enrichment, so that “Modern C”, namely with a mean radiocarbon age lower than 200 years, is present also deeper than 45 cm in the Bo2 horizon. The mean residence time (MRT) estimated from radiocarbon content are of the order of a few decades in the topsoil and a few centuries in the deeper horizons. Altogether, the MRT values indicate a fast recycle of C compared to temperate or boreal forests, but not as fast as usually believed for tropical forest soils. Making a pondered mean, in the Ankasa forest the time an atom of C resides in soil is not much different from one atom of C in the woody aboveground biomass. Hence, the contribution of soil in storing C is substantial, implying that in primary rainforests it is mandatory to determine the SOC stock and its dynamics, too often neglected or underestimated. 相似文献
2.
Toshiyuki Ohtsuka Masaya Negishi Kazuyuki Sugita Yasuo Iimura Mitsuru Hirota 《Ecological Research》2013,28(5):855-867
Biometric-based carbon flux measurements were conducted in a pine forest on lava flow of Mt. Fuji, Japan, in order to estimate carbon cycling and sequestration. The forest consists mainly of Japanese red pine (Pinus densiflora) in a canopy layer and Japanese holly (Ilex pedunculosa) in a subtree layer. The lava remains exposed on the ground surface, and the soil on the lava flow is still immature with no mineral soil layer. The results showed that the net primary production (NPP) of the forest was 7.3 ± 0.7 t C ha?1 year?1, of which 1.4 ± 0.4 t C ha?1 year?1 was partitioned to biomass increment, 3.2 ± 0.5 t C ha?1 year?1 to above-ground fine litter production, 1.9 t C ha?1 year?1 to fine root production, and 0.8 ± 0.2 t C ha?1 year?1 to coarse woody debris. The total amount of annual soil surface CO2 efflux was estimated as 6.1 ± 2.9 t C ha?1 year?1, using a closed chamber method. The estimated decomposition rate of soil organic matter, which subtracted annual root respiration from soil respiration, was 4.2 ± 3.1 t C ha?1 year?1. Biometric-based net ecosystem production (NEP) in the pine forest was estimated at 2.9 ± 3.2 t C ha?1 year?1, with high uncertainty due mainly to the model estimation error of annual soil respiration and root respiration. The sequestered carbon being allocated in roughly equal amounts to living biomass (1.4 t C ha?1 year?1) and the non-living C pool (1.5 t C ha?1 year?1). Our estimate of biometric-based NEP was 25 % lower than the eddy covariance-based NEP in this pine forest, due partly to the underestimation of NPP and difficulty of estimation of soil and root respiration in the pine forest on lava flows that have large heterogeneity of soil depth. However, our results indicate that the mature pine forest acted as a significant carbon sink even when established on lava flow with low nutrient content in immature soils, and that sequestration strength, both in biomass and in soil organic matter, is large. 相似文献
3.
Optimizing Carbon Storage Within a Spatially Heterogeneous Upland Grassland Through Sheep Grazing Management 总被引:2,自引:0,他引:2
Stuart W. Smith Charlotte Vandenberghe Astley Hastings David Johnson Robin J. Pakeman René van der Wal Sarah J. Woodin 《Ecosystems》2014,17(3):418-429
Livestock grazing is known to influence carbon (C) storage in vegetation and soil. Yet, for grazing management to be used to optimize C storage, large scale investigations that take into account the typically heterogeneous distribution of grazers and C across the landscape are required. In a landscape-scale grazing experiment in the Scottish uplands, we quantified C stored in swards dominated by the widespread tussock-forming grass species Molinia caerulea. The impact of three sheep stocking treatments (‘commercial’ 2.7 ewes ha?1 y?1, ‘low’ 0.9 ewes ha?1 y?1 and no livestock) on plant C stocks was determined at three spatial scales; tussock, sward and landscape, and these data were used to predict long-term changes in soil organic carbon (SOC). We found that tussocks were particularly dense C stores (that is, high C mass per unit area) and that grazing reduced their abundance and thus influenced C stocks held in M. caerulea swards across the landscape; C stocks were 3.83, 5.01 and 6.85 Mg C ha?1 under commercial sheep grazing, low sheep grazing and no grazing, respectively. Measured vegetation C in the three grazing treatments provided annual C inputs to RothC, an organic matter turnover model, to predict changes in SOC over 100 years. RothC predicted SOC to decline under commercial sheep stocking and increase under low sheep grazing and no grazing. Our findings suggest that no sheep and low-intensity sheep grazing are better upland management practices for enhancing plant and soil C sequestration than commercial sheep grazing. This is evaluated in the context of other upland management objectives. 相似文献
4.
Mascha Jacob Claudia Bade Héctor Calvete Sebastian Dittrich Christoph Leuschner Markus Hauck 《Ecosystems》2013,16(2):336-346
Old-growth forests are important stores for carbon as they may accumulate C for centuries. The alteration of biomass and soil carbon pools across the development stages of a forest dynamics cycle has rarely been quantified. We studied the above- and belowground C stocks in the five forest development stages (regeneration to decay stage) of a montane spruce (Picea abies) forest of the northern German Harz Mountains, one of Central Europe’s few forests where the natural forest dynamics have not been disturbed by man for several centuries. The over-mature and decay stages had the largest total (up to 480 Mg C ha?1) and aboveground biomass carbon pools (200 Mg C ha?1) with biomass C stored in dead wood in the decay stage. The soil C pool (220–275 Mg C ha?1, 0–60 cm) was two to three times larger than in temperate lowland spruce forests and remained invariant across the forest dynamics cycle. On the landscape level, taking into account the frequency of the five forest development stages, the total carbon pool was approximately 420 Mg C ha?1. The results evidence the high significance of over-mature and decaying stages of temperate mountain forests not only for conserving specialized forest organisms but also for their large carbon storage potential. 相似文献
5.
Soil organic carbon dynamics 75 years after land-use change in perennial grassland and annual wheat agricultural systems 总被引:1,自引:0,他引:1
Joshua W. Beniston S. Tianna DuPont Jerry D. Glover Rattan Lal Jennifer A. J. Dungait 《Biogeochemistry》2014,120(1-3):37-49
The dynamics of roots and soil organic carbon (SOC) in deeper soil layers are amongst the least well understood components of the global C cycle, but essential if soil C is to be managed effectively. This study utilized a unique set of land-use pairings of harvested tallgrass prairie grasslands (C4) and annual wheat croplands (C3) that were under continuous management for 75 years to investigate and compare the storage, turnover and allocation of SOC in the two systems to 1 m depth. Cropland soils contained 25 % less SOC than grassland soils (115 and 153 Mg C ha?1, respectively) to 1 m depth, and had lower SOC contents in all particle size fractions (2000–250, 250–53, 53–2 and <2 μm), which nominally correspond to SOC pools with different stability. Soil bulk δ13C values also indicated the significant turnover of grassland-derived SOC up to 80 cm depth in cropland soils in all fractions, including deeper (>40 cm) layers and mineral-associated (<53 μm) SOC. Grassland soils had significantly more visible root biomass C than cropland soils (3.2 and 0.6 Mg ha?1, respectively) and microbial biomass C (3.7 and 1.3 Mg ha?1, respectively) up to 1 m depth. The outcomes of this study demonstrated that: (i) SOC pools that are perceived to be stable, i.e. subsoil and mineral-associated SOC, are affected by land-use change; and, (ii) managed perennial grasslands contained larger SOC stocks and exhibited much larger C allocations to root and microbial pools than annual croplands throughout the soil profile. 相似文献
6.
Nirav Mehta Neeta R. Pandya V. O. Thomas N. S. R. Krishnayya 《Ecological Research》2014,29(6):1053-1063
Alterations in precipitation are affecting forest ecosystems’ soil carbon cycling. To understand how shifts in rainfall may alter these carbon pools, above-ground biomass (AGB), soil organic carbon (SOC), and microbial biomass carbon (MBC) of tropical forest covers were measured across a rainfall gradient (543–1590 mm) in Gujarat (India), a state falling under semi arid to tropical dry–wet conditions. Species diversity, tree density and soil texture were also measured. Field visits and data collection were carried out for 2 years (2009–2011) in 95 plots of 250 × 250 m in the forest covers across four distinct rainfall zones (RFZs). Data analysis showed that differences seen in the values of the measured parameters across the RFZs are statistically significant (P < 0.05). Positive correlations were observed between mean annual precipitation (MAP) and tree density, species diversity, AGB, SOC, and MBC. Across the RFZs, AGB ranged between 0.09 and 168.28 Mg ha?1; SOC values (up to 25 cm soil depth) varied between 2.94 and 147.84 Mg ha?1. Soil texture and MBC showed a significant impact on the dynamics of SOC in all the RFZs. MBC is more influenced by SOC rather than AGB. Both vegetation type and MAP have an important role in the regulation of SOC in tropical soils. Together, these results reveal complex carbon cycle responses are likely to occur in tropical soils under altered rainfall regimes. 相似文献
7.
Jonas Glatthorn Eike Feldmann Viliam Pichler Markus Hauck Christoph Leuschner 《Ecosystems》2018,21(4):704-722
Our knowledge of temperate broadleaf forest ecology is based mostly on the study of production forests, which lack the terminal stage of forest development and have a simpler stand structure than old-growth and primeval forests. How primeval and production forests differ in net primary production (NPP) is not well known. In three primeval and three nearby production forests of European beech (Fagus sylvatica) in the Slovakian Carpathians, we measured aboveground biomass stocks (live and dead), aboveground NPP (ANPP) and parameters characterizing canopy structural diversity (leaf area index and its spatial variation). Our study aims were (1) to explore the role of canopy structural diversity for ANPP and (2) to assess evidence of a productivity decline in the terminal stage. While aboveground live biomass stocks were on average 20% greater in the primeval forests (386 vs. 320 Mg ha?1; insignificant difference at two sites), deadwood mass stocks were on average four times larger than in the production forests (86 vs. 19 Mg ha?1). ANPP was similarly high in the primeval and production forests (10.0 vs. 9.9 Mg ha?1 y?1) and did not decrease towards the terminal stage. Production models indicate that, in the primeval forests, about 10% of ANPP (ca. 1 Mg ha?1 y?1) was generated by effects related to leaf area heterogeneity, evidencing a positive effect of structural diversity on forest productivity, even though species diversity was low. This study helps to better understand the impact of forest management on the productivity and carbon storage in temperate woodlands. 相似文献
8.
The transfer of carbon (C) from Amazon forests to aquatic ecosystems as CO2 supersaturated in groundwater that outgases to the atmosphere after it reaches small streams has been postulated to be an important component of terrestrial ecosystem C budgets. We measured C losses as soil respiration and methane (CH4) flux, direct CO2 and CH4 fluxes from the stream surface and fluvial export of dissolved inorganic C (DIC), dissolved organic C (DOC), and particulate C over an annual hydrologic cycle from a 1,319-ha forested Amazon perennial first-order headwater watershed at Tanguro Ranch in the southern Amazon state of Mato Grosso. Stream pCO2 concentrations ranged from 6,491 to 14,976 ??atm and directly-measured stream CO2 outgassing flux was 5,994 ± 677 g C m?2 y?1 of stream surface. Stream pCH4 concentrations ranged from 291 to 438 ??atm and measured stream CH4 outgassing flux was 987 ± 221 g C m?2 y?1. Despite high flux rates from the stream surface, the small area of stream itself (970 m2, or 0.007% of watershed area) led to small directly-measured annual fluxes of CO2 (0.44 ± 0.05 g C m2 y?1) and CH4 (0.07 ± 0.02 g C m2 y?1) per unit watershed land area. Measured fluvial export of DIC (0.78 ± 0.04 g C m?2 y?1), DOC (0.16 ± 0.03 g C m?2 y?1) and coarse plus fine particulate C (0.001 ± 0.001 g C m?2 y?1) per unit watershed land area were also small. However, stream discharge accounted for only 12% of the modeled annual watershed water output because deep groundwater flows dominated total runoff from the watershed. When C in this bypassing groundwater was included, total watershed export was 10.83 g C m?2 y?1 as CO2 outgassing, 11.29 g C m?2 y?1 as fluvial DIC and 0.64 g C m?2 y?1 as fluvial DOC. Outgassing fluxes were somewhat lower than the 40?C50 g C m?2 y?1 reported from other Amazon watersheds and may result in part from lower annual rainfall at Tanguro. Total stream-associated gaseous C losses were two orders of magnitude less than soil respiration (696 ± 147 g C m?2 y?1), but total losses of C transported by water comprised up to about 20% of the ± 150 g C m?2 (±1.5 Mg C ha?1) that is exchanged annually across Amazon tropical forest canopies. 相似文献
9.
Jane M. F. Johnson Jeff M. Novak Gary E. Varvel Diane E. Stott Shannon L. Osborne Douglas L. Karlen John A. Lamb John Baker Paul R. Adler 《Bioenergy Research》2014,7(2):481-490
Corn’s (Zea mays L.) stover is a potential nonfood, herbaceous bioenergy feedstock. A vital aspect of utilizing stover for bioenergy production is to establish sustainable harvest criteria that avoid exacerbating soil erosion or degrading soil organic carbon (SOC) levels. Our goal is to empirically estimate the minimum residue return rate required to sustain SOC levels at numerous locations and to identify which macroscale factors affect empirical estimates. Minimum residue return rate is conceptually useful, but only if the study is of long enough duration and a relationship between the rate of residue returned and the change in SOC can be measured. About one third of the Corn Stover Regional Partnership team (Team) sites met these criteria with a minimum residue return rate of 3.9?±?2.18 Mg stover ha?1 yr?1, n?=?6. Based on the Team and published corn-based data (n?=?35), minimum residue return rate was 6.38?±?2.19 Mg stover ha?1 yr?1, while including data from other cropping systems (n?=?49), the rate averaged 5.74?±?2.36 Mg residue ha?1 yr?1. In broad general terms, keeping about 6 Mg residue ha?1 yr?1 maybe a useful generic rate as a point of discussion; however, these analyses refute that a generic rate represents a universal target on which to base harvest recommendations at a given site. Empirical data are needed to calibrate, validate, and refine process-based models so that valid sustainable harvest rate guidelines are provided to producers, industry, and action agencies. 相似文献
10.
Li-Hua Tu Ting-Xing Hu Jian Zhang Ren-Hong Li Hong-Zhong Dai Shou-Hua Luo 《Plant and Soil》2011,340(1-2):383-396
In order to understand the influence of nitrogen (N) deposition on the key processes relevant to the carbon (C) balance in a bamboo plantation, a two-year field experiment involving the simulated deposition of N in a Pleioblastus amarus plantation was conducted in the rainy region of SW China. Four levels of N treatments: control (no N added), low-N (50 kg N ha?1 year?1), medium-N (150 kg N ha?1 year?1), and high-N (300 kg N ha?1 year?1) were set in the present study. The results showed that soil respiration followed a clear seasonal pattern, with the maximum rates in mid-summer and the minimum in late winter. The annual cumulative soil respiration was 585?±?43 g CO2-C m?2 year?1 in the control plots. Simulated N deposition significantly increased the mean annual soil respiration rate, fine root biomass, soil microbial biomass C (MBC), and N concentration in fine roots and fresh leaf litter. Soil respirations exhibited a positive exponential relationship with soil temperature, and a linear relationship with MBC. The net primary production (NPP) ranged from 10.95 to 15.01 Mg C ha?1 year?1 and was higher than the annual soil respiration (5.85 to 7.62 Mg C ha?1 year?1) in all treatments. Simulated N deposition increased the net ecosystem production (NEP), and there was a significant difference between the control and high N treatment NEP, whereas, the difference of NEP among control, low-N, and medium-N was not significant. Results suggest that N controlled the primary production in this bamboo plantation ecosystem. Simulated N deposition increased the C sequestration of the P. amarus plantation ecosystem through increasing the plant C pool, though CO2 emission through soil respiration was also enhanced. 相似文献
11.
Changes in soil organic carbon and total nitrogen stocks after conversion of meadow to cropland in Northeast China 总被引:1,自引:0,他引:1
Fan Ding Ya-Lin Hu Lu-Jun Li Ang Li Shengwei Shi Pei-Yong Lian De-Hui Zeng 《Plant and Soil》2013,373(1-2):659-672
Aims
Grassland conversion to cropland (GCC) may result in loss of a large amount of soil organic carbon (SOC). However, the assessment of such loss of SOC still involves large uncertainty due to shallow sampling depth, soil bulk density estimation and spatial heterogeneity. Our objectives were to quantify changes in SOC, soil total nitrogen (STN) and C:N ratio in 0–100 cm soil profile after GCC and to clarify factors influencing the SOC change.Methods
A nest-paired sampling design was used in six sites along a temperature gradient in Northeast China.Results
SOC change after GCC ranged from ?17 to 0 Mg ha?1 in 0–30 cm soil layer, recommended by IPCC, across the six sites, but ranged from ?30 to 7 Mg ha?1 when considering 0–100 cm. We found a linear relationship between SOC change in 30–100 cm and that in 0–30 cm profile (ΔC30?100?=?0.35ΔC0?30, P?<?0.001), suggesting that SOC change in 0–100 cm was averagely 35 % higher than that in 0–30 cm. The change in STN showed a similar pattern to SOC, and soil C:N ratio did not change at most of sites. On the other hand, SOC loss after GCC was greater in soils with higher initial SOC content or in croplands without applying chemical fertilizers. Furthermore, SOC loss after GCC decreased with falling mean annual temperature (MAT), and even vanished in the coldest sites.Conclusions
The magnitude of SOC loss following GCC in Northeast China is lower than the global average value, partly due to low MAT here. However, the current low SOC loss can be intensified by remarkable climate warming in this region. 相似文献12.
Benjamin Loubet Patricia Laville Simon Lehuger Eric Larmanou Christophe Fl��chard Nicolas Mascher Sophie Genermont Romain Roche Rossana M. Ferrara Patrick Stella Erwan Personne Brigitte Durand C��line Decuq Dominique Flura Sylvie Masson Olivier Fanucci Jean-No?l Rampon Jan Siemens Reimo Kindler Benoit Gabrielle Marion Schrumpf Pierre Cellier 《Plant and Soil》2011,343(1-2):109-137
Croplands mainly act as net sources of the greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O), as well as nitrogen oxide (NO), a precursor of troposheric ozone. We determined the carbon (C) and nitrogen (N) balance of a four-year crop rotation, including maize, wheat, barley and mustard, to provide a base for exploring mitigation options of net emissions. The crop rotation had a positive net ecosystem production (NEP) of 4.4?±?0.7 Mg C ha-1 y-1 but represented a net source of carbon with a net biome production (NBP) of -1.3?±?1.1 Mg C?ha-1 y-1. The nitrogen balance of the rotation was correlated with the carbon balance and resulted in net loss (?24?±?28 kg N ha-1 y-1). The main nitrogen losses were nitrate leaching (?11.7?±1.0 kg N ha-1 y-1) and ammonia volatilization (?9 kg N ha-1 y-1). Dry and wet depositions were 6.7?±?3.0 and 5.9?±0.1 kg N ha-1 y-1, respectively. Fluxes of nitrous (N2O) and nitric (NO) oxides did not contribute significantly to the N budget (N2O: -1.8?±?0.04; NO: -0.7?±?0.04 kg N ha-1 y-1) but N2O fluxes equaled 16% of the total greenhouse gas balance. The link between the carbon and nitrogen balances are discussed. Longer term experiments would be necessary to capture the trends in the carbon and nitrogen budgets within the variability of agricultural ecosystems. 相似文献
13.
Christina Tonitto Christine L. Goodale Marissa S. Weiss Serita D. Frey Scott V. Ollinger 《Biogeochemistry》2014,117(2-3):431-454
Recent observations indicate that long-term N additions can slow decomposition, leading to C accumulation in soils, but this process has received limited consideration by models. To address this, we developed a model of soil organic matter (SOM) dynamics to be used with the PnET model and applied it to simulate N addition effects on soil organic carbon (SOC) stocks. We developed the model’s SOC turnover times and responses to experimental N additions using measurements from the Harvard Forest, Massachusetts. We compared model outcomes to SOC stocks measured during the 20th year of the Harvard Forest Chronic Nitrogen Amendment Study, which includes control, low (5 g N m?2 yr?1) and high (15 g N m?2 yr?1) N addition to hardwood and red pine stands. For unfertilized stands, simulated SOC stocks were within 10 % of measurements. Simulations that used measured changes in decomposition rates in response to N accurately captured SOC stocks in the hardwood low N and pine high N treatment, but greatly underestimated SOC stocks in the hardwood high N and the pine low N treatments. Simulated total SOC response to experimental N addition resulted in accumulation of 5.3–7.9 kg C per kg N following N addition at 5 g N m?2 yr?1 and 4.1–5.3 kg C per kg N following N addition at 15 g N m?2 yr?1. Model simulations suggested that ambient atmospheric N deposition at the Harvard Forest (currently 0.8 g N m?2 yr?1) has led to an increase in cumulative O, A, and B horizons C stocks of 211 g C m?2 (3.9 kg C per kg N) and 114 g C m?2 (2.1 kg C per kg N) for hardwood and pine stands, respectively. Simulated SOC accumulation is primarily driven by the modeled decrease in SOM decomposition in the Oa horizon. 相似文献
14.
The boreal forest plays a key role in the global carbon (C) cycle, and black spruce (Picea mariana (Mill.) BSP) forests are the dominant coniferous forest type in the Canadian boreal forest. National-scale forest C models currently do not account for the contribution of moss-derived organic matter that we hypothesize to be significant in the C budget of black spruce ecosystems. One such model, the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3), is designed to meet Canada’s forest-related greenhouse gas reporting requirements. In this study our goal was to determine if black spruce forest soil C stocks are significantly underestimated by the CBM-CFS3, and if so, to determine if estimates could be improved by adding moss-derived C. We conclude that in black spruce sites, organic layer C is significantly underestimated by CBM-CFS3 compared to sites with all other leading tree species analyzed. We compiled and used published moss net primary productivity rates for upland forest systems, with decomposition rates, in mass-balance calculations to estimate mean moss-derived C in black spruce forests for feather mosses at 64 Mg C ha?1, and for sphagnum mosses at 103 Mg C ha?1. These C pools are similar to the CBM-CFS3 mean underestimation of black spruce soil organic layers (63 Mg C ha?1). We conclude that the contribution of mosses is sufficiently large that a moss C pool should be added to national-scale models including the CBM-CFS3, to reduce uncertainties in boreal forest C budget estimation. Feather and sphagnum mosses should be parameterized separately. 相似文献
15.
Werner L. Kutsch Tryggve Persson Marion Schrumpf Fernando E. Moyano Martina Mund Stefan Andersson Ernst-Detlef Schulze 《Biogeochemistry》2010,100(1-3):167-183
Three different approaches were used to calculate heterotrophic soil respiration (Rh) and soil carbon dynamics in an old-growth deciduous forest in central Germany. A root and mycorrhiza exclosure experiment in the field separated auto- and heterotrophic soil respiration. It was compared to modeled heterotrophic respiration resulting from two different approaches: a modular component model of soil respiration calculated autotrophic and heterotrophic soil respiration with litter, climate and canopy photosynthesis as input variables. It was calibrated by independent soil respiration measurements in the field. A second model was calibrated by incubation of soil samples from different soil layers in the laboratory. In this case, the annual sum of Rh was calculated by an empirical model including response curves to temperature and a soil moisture. The three approaches showed good accordance during spring and summer and when the annual sums of Rh calculated by the two models were compared. Average Rh for the years 2002–2006 were 436 g C m?2 year?1 (field model) and 417 g C m?2 year?1 (lab-model), respectively. Differences between the approaches revealed specific limitations of each method. The average carbon balance of the Hainich forest soil was estimated to be between 1 and 35 g C m?2 year?1 depending on the model used and the averaging period. A comparison with nighttime data from eddy covariance (EC) showed that EC data were lower than modelled soil respiration in many situations. We conclude that better filter methods for EC nighttime data have to be developed. 相似文献
16.
Crop residues like corn (Zea mays L.) stover perform important functions that promote soil health and provide ecosystem services that influence agricultural sustainability and global biogeochemical cycles. We evaluated the effect of corn stover removal from a no-till, corn-soybean (Glycine max (L.) Merr) rotation on soil greenhouse gas (GHG; CO2, N2O, CH4) fluxes, crop yields, and soil organic carbon (SOC) dynamics. We conducted a 4-year study using replicated field plots managed with two levels of corn stover removal (none; 55 % stover removal) for four complete crop cycles prior to initiation of ground surface gas flux measurements. Corn and soybean yields were not affected by stover removal with yields averaging 7.28 Mg ha?1 for corn and 2.64 Mg ha?1 for soybean. Corn stover removal treatment did not affect soil GHG fluxes from the corn phase; however, the treatment did significantly increase (107 %, P?=?0.037) N2O fluxes during the soybean phase. The plots were a net source of CH4 (~0.5 kg CH4-C ha?1 year?1 average of all treatments and crops) during the generally wet study duration. Soil organic carbon stocks increased in both treatments during the 4-year study (initiated following 8 years of stover removal), with significantly higher SOC accumulation in the control plots compared to plots with corn stover removal (0–15 cm, P?=?0.048). Non-CO2 greenhouse gas emissions (945 kg CO2-eq ha?1 year?1) were roughly half of SOC (0–30 cm) gains with corn stover removal (1.841 Mg CO2-eq ha?1 year?1) indicating that no-till practices greatly improve the viability of biennial corn stover harvesting under local soil-climatic conditions. Our results also show that repeated corn stover harvesting may increase N loss (as N2O) from fields and thereby contribute to GHG production and loss of potential plant nutrients. 相似文献
17.
The quantification of silicon (Si) uptake by tree species is a mandatory step to study the role of forest vegetations in the global cycle of Si. Forest tree species can impact the hydrological output of dissolved Si (DSi) through root induced weathering of silicates but also through Si uptake and restitution via litterfall. Here, monospecific stands of Douglas fir, Norway spruce, Black pine, European beech and oak established in identical soil and climate conditions were used to quantify Si uptake, immobilization and restitution. We measured the Si contents in various compartments of the soil–tree system and we further studied the impact of the recycling of Si by forest trees on the DSi pool. Si is mainly accumulated in leaves and needles in comparison with other tree compartments (branches, stembark and stemwood). The immobilization of Si in tree biomass represents less than 15% of the total Si uptake. Annual Si uptake by oak and European beech stands is 18.5 and 23.3 kg ha?1 year?1, respectively. Black pine has a very low annual Si uptake (2.3 kg ha?1 year?1) in comparison with Douglas fir (30.6 kg ha?1 year?1) and Norway spruce (43.5 kg ha?1 year?1). The recycling of Si by forest trees plays a major role in the continental Si cycle since tree species greatly influence the uptake and restitution of Si. Moreover, we remark that the annual tree uptake is negatively correlated with the annual DSi output at 60 cm depth. The land–ocean fluxes of DSi are certainly influenced by geochemical processes such as weathering of primary minerals and formation of secondary minerals but also by biological processes such as root uptake. 相似文献
18.
Fertilization enhancing carbon sequestration as carbonate in arid cropland: assessments of long-term experiments in northern China 总被引:4,自引:0,他引:4
X. J. Wang M. G. Xu J. P. Wang W. J. Zhang X. Y. Yang S. M. Huang H. Liu 《Plant and Soil》2014,380(1-2):89-100
Aims
Soil inorganic carbon (SIC), primarily calcium carbonate, is a major reservoir of carbon in arid lands. This study was designed to test the hypothesis that carbonate might be enhanced in arid cropland, in association with soil fertility improvement via organic amendments.Methods
We obtained two sets (65 each) of archived soil samples collected in the early and late 2000’s from three long-term experiment sites under wheat-corn cropping with various fertilization treatments in northern China. Soil organic (SOC), SIC and their Stable 13C compositions were determined over the range 0–100 cm.Results
All sites showed an overall increase of SIC content in soil profiles over time. Particularly, fertilizations led to large SIC accumulation with a range of 101–202 g C m?2 y?1 in the 0–100 cm. Accumulation of pedogenic carbonate under fertilization varied from 60 to 179 g C m?2 y?1 in the 0–100 cm. Organic amendments significantly enhanced carbonate accumulation, in particular in the subsoil.Conclusions
More carbon was sequestrated in the form of carbonate than as SOC in the arid cropland in northern China. Increasing SOC stock through long-term straw incorporation and manure application in the arid and semi-arid regions also enhanced carbonate accumulation in soil profiles. 相似文献19.
Srabani Das Karin Teuffer Cathelijne R. Stoof Michael F. Walter M. Todd Walter Tammo S. Steenhuis Brian K. Richards 《Bioenergy Research》2018,11(2):262-276
The control of soil moisture, vegetation type, and prior land use on soil health parameters of perennial grass cropping systems on marginal lands is not well known. A fallow wetness-prone marginal site in New York (USA) was converted to perennial grass bioenergy feedstock production. Quadruplicate treatments were fallow control, reed canarygrass (Phalaris arundinaceae L. Bellevue) with nitrogen (N) fertilizer (75 kg N ha?1), switchgrass (Panicum virgatum L. Shawnee), and switchgrass with N fertilizer (75 kg N ha?1). Based on periodic soil water measurements, permanent sampling locations were assigned to various wetness groups. Surface (0–15 cm) soil organic carbon (SOC), active carbon, wet aggregate stability, pH, total nitrogen (TN), root biomass, and harvested aboveground biomass were measured annually (2011–2014). Multi-year decreases in SOC, wet aggregate stability, and pH followed plowing in 2011. For all years, wettest soils had the greatest SOC and active carbon, while driest soils had the greatest wet aggregate stability and lowest pH. In 2014, wettest soils had significantly (p?<?0.0001) greater SOC and TN than drier soils, and fallow soils had 14 to 20% greater SOC than soils of reed canarygrass + N, switchgrass, and switchgrass + N. Crop type and N fertilization did not result in significant differences in SOC, active carbon, or wet aggregate stability. Cumulative 3-year aboveground biomass yields of driest switchgrass + N soils (18.8 Mg ha?1) were 121% greater than the three wettest switchgrass (no N) treatments. Overall, soil moisture status must be accounted for when assessing soil dynamics during feedstock establishment. 相似文献
20.
Martine Janet van de Weg Patrick Meir Mat Williams Cécile Girardin Yadvinder Malhi Javier Silva-Espejo John Grace 《Ecosystems》2014,17(5):751-764
For decades, the productivity of tropical montane cloud forests (TMCF) has been assumed to be lower than in tropical lowland forests due to nutrient limitation, lower temperatures, and frequent cloud immersion, although actual estimates of gross primary productivity (GPP) are very scarce. Here, we present the results of a process-based modeling estimate of GPP, using a soil–plant–atmosphere model, of a high elevation Peruvian TMCF. The model was parameterized with field-measured physiological and structural vegetation variables, and driven with meteorological data from the site. Modeled transpiration corroborated well with measured sap flow, and simulated GPP added up to 16.2 ± SE 1.6 Mg C ha?1 y?1. Dry season GPP was significantly lower than wet season GPP, although this difference was 17% and not caused by drought stress. The strongest environmental controls on simulated GPP were variation of photosynthetic active radiation and air temperature (T air). Their relative importance likely varies with elevation and the local prevalence of cloud cover. Photosynthetic parameters (V cmax and J max) and leaf area index were the most important non-environmental controls on GPP. We additionally compared the modeled results with a recent estimate of GPP of the same Peruvian TMCF derived by the summing of ecosystem respiration and net productivity terms, which added up to 26 Mg C ha?1 y?1. Despite the uncertainties in modeling GPP we conclude that at this altitude GPP is, conservatively estimated, 30–40% lower than in lowland rainforest and this difference is driven mostly by cooler temperatures than changes in other parameters. 相似文献