共查询到20条相似文献,搜索用时 15 毫秒
1.
Shi-xing Zhou Cong-de Huang Bo-han Han Yong-xiang Xiao Jian-dong Tang Yuan-bin Xiang Chao Luo 《Plant and Soil》2017,420(1-2):135-145
Background and aims
Litter, an essential component of forest ecosystems, plays an important role in maintaining soil fertility, sequestering carbon (C) and improving soil biodiversity. However, litter decomposition is affected by increased nitrogen (N) deposition. Numerous reports have presented N deposition experiments in different forest ecosystems to investigate the effects of N deposition on litter decomposition, but the effects remain unclear, especially in ecosystems receiving increasingly higher levels of ambient N deposition. To address this gap, we performed a litterbag experiment to understand the effects of increasing N deposition on the litter decomposition process in natural evergreen broad-leaved forest in the Rainy Area of Western China.Methods
A 2-year field litter decomposition experiment was conducted using the litterbag method. Four levels of N deposition were established: control (CK; 0 kg·N·ha?1·year?1), low N deposition (LN; 50 kg·N·ha?1·year?1), medium N deposition (MN; 150 kg·N·ha?1·year?1), and high N deposition (HN; 300 kg·N·ha?1·year?1). The simulated N depositions ranged from 50% to 320% of the ambient rate of wet N deposition.Results
Simulated N deposition significantly increased the remaining mass, C, N, lignin and cellulose of the litter. The LN treatment decreased the remaining phosphorus (P); conversely, the HN treatment increased it. In the late stage of the study period, the mass remaining was positively closely correlated to the lignin and cellulose remaining during the decomposition process.Conclusions
Simulated N deposition significantly suppressed the litter decomposition in the natural evergreen broad-leaved forest, despite the high rate of ambient N deposition, and the inhibitory effects increased with the N deposition levels. The suppressive effect of N deposition on litter decomposition may be primarily explained by the inhibition of lignin and cellulose degradation by the exogenous inorganic N. With ongoing N deposition in future, N deposition may have a potentially significant impact on C and N cycles in such forest ecosystems.2.
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
3.
Aims
Carbon (C) bio-sequestration within the phytoliths of plants, a mechanism of long-term biogeochemical C sequestration, may play a major role in the global C cycle and climate change. In this study, we explored the potential of C bio-sequestration within phytoliths produced in cultivated rice (Oryza sativa), a well known silicon accumulator.Methods
The rice phytolith extraction was undertaken with microwave digestion procedures and the determination of occluded C in phytoliths was based on dissolution methods of phytolith-Si.Results
Chemical analysis indicates that the phytolith-occluded C (PhytOC) contents of the different organs (leaf, stem, sheath and grains) on a dry weight basis in 5 rice cultivars range from 0.4 mg?g?1 to 2.8 mg?g?1, and the C content of phytoliths from grains is much lower than that of leaf, stem and sheath. The data also show that the PhytOC content of rice depends on both the content of phytoliths and the efficiency of C occlusion within phytoliths during rice growth. The biogeochemical C sequestration flux of phytoliths in 5 rice cultivars is approximately 0.03–0.13 Mg of carbon dioxide (CO2) equivalents (Mg-e-CO2) ha?1?year?1. From 1950 to 2010, about 2.37?×?108?Mg of CO2 equivalents might have been sequestrated within the rice phytoliths in China. Assuming a maximum phytoliths C bio-sequestration flux of 0.13 Mg-e-CO2 ha?1?year?1, the global annual potential rate of CO2 sequestrated in rice phytoliths would approximately be 1.94?×?107?Mg.Conclusions
Therefore rice crops may play a significant role in long-term C sequestration through the formation of PhytOC. 相似文献4.
Assessment of carbon sustainability under different tillage systems in a double rice cropping system in Southern China 总被引:1,自引:0,他引:1
Jian-Fu Xue Sheng-Li Liu Zhong-Du Chen Fu Chen Rattan Lal Hai-Ming Tang Hai-Lin Zhang 《The International Journal of Life Cycle Assessment》2014,19(9):1581-1592
Purpose
Adoption of the carbon (C)-friendly and cleaner technology is an effective solution to offset some of the anthropogenic emissions. Conservation tillage is widely considered as an important sustainable technology and for the development of conservation agriculture (CA). Thus, the objective of this study was to assess the C sustainability of different tillage systems in a double rice (Oryza sativa L.) cropping system in southern China.Methods
The experiment was established with no-till (NT), rotary tillage (RT), and conventional tillage (CT) treatments since 2005. Emission of greenhouse gasses (GHG), C footprint (CF), and ecosystem service through C sequestration in different tillage systems were compared.Result and discussion
Emission of GHG from agricultural inputs (Mg CO2-eq ha?1 year?1) ranged from 1.81 to 1.97 for the early rice, 1.82 to 1.98 for the late rice, and 3.63 to 3.95 for the whole growing season, respectively. The CF (kg CO2-eq kg?1 of rice year?1) in the whole growing seasons were 1.27, 1.85, and 1.40 [excluding soil organic carbon (SOC) storage] and 0.54, 1.20, and 0.72 (including SOC storage) for NT, RT, and CT, respectively. The value of ecosystem services on C sequestration for the whole growing seasons ranged from ¥3,353 to 4,948 ha?1 year?1 and followed the order of NT > CT > RT. The C sustainability under NT was better than that under RT for the late, but reversed for the early rice. However, NT system had better C sustainability for the whole cropping system compared with CT.Conclusions
Therefore, NT is a preferred technology to reduce GHG emissions, increase ecosystem service functions of C sequestration, and improve C sustainability in a double rice cropping region of Southern China. 相似文献5.
Aims
The interactive effects of enhanced nitrogen (N) deposition and ultraviolet-B (UV-B) radiation on litter decomposition are still unknown. The aims are to test whether the interactive effects of the two environmental factors on litter decomposition and nutrient loss are stronger than that of each factor alone.Methods
Experiment included five treatments: elevated UV-B radiation (UV-B, 10 % enhancement), low N addition (N1, 30 kg N ha?1 year?1), high N addition (N2, 60 kg N ha?1 year?1), the two combined treatments of the two factors (UV-B+N1 and UV-B+N2), and an unmanipulated control.Results
The annual decomposition rates under combination of UV-B and N addition significantly decreased compared with that under UV-B and N additions for Pinus massoniana, and did also compared with that under UV-B but did not significantly differ with N additions for Cyclobalanopsis glauca. Negative effects of N additions alone on lignin degradation and P loss were partly offset but negative effect on N loss was further amplified when was combined with UV-B.Conclusions
The combination of N deposition and UV-B radiation on litter decomposition and nutrient loss was significantly different from that of each factor alone without a general response pattern of decomposition, and was regulated by litter chemistry. 相似文献6.
Nitrous oxide emissions and nitrate leaching from a rain-fed wheat-maize rotation in the Sichuan Basin, China 总被引:3,自引:0,他引:3
Minghua Zhou Bo Zhu Klaus Butterbach-Bahl Xunhua Zheng Tao Wang Yanqiang Wang 《Plant and Soil》2013,362(1-2):149-159
Aims
A 3-year field experiment (October 2004–October 2007) was conducted to quantify N2O fluxes and determine the regulating factors from rain-fed, N fertilized wheat-maize rotation in the Sichuan Basin, China.Methods
Static chamber-GC techniques were used to measure soil N2O fluxes in three treatments (three replicates per treatment): CK (no fertilizer); N150 (300 kg N fertilizer ha?1 yr?1 or 150 kg N?ha?1 per crop); N250 (500 kg N fertilizer ha?1 yr?1 kg or 250 kg N?ha?1 per crop). Nitrate (NO 3 ? ) leaching losses were measured at nearby sites using free-drained lysimeters.Results
The annual N2O fluxes from the N fertilized treatments were in the range of 1.9 to 6.7 kg N?ha?1 yr?1 corresponding to an N2O emission factor ranging from 0.12 % to 1.06 % (mean value: 0.61 %). The relationship between monthly soil N2O fluxes and NO 3 - leaching losses can be described by a significant exponential decaying function.Conclusions
The N2O emission factor obtained in our study was somewhat lower than the current IPCC default emission factor (1 %). Nitrate leaching, through removal of topsoil NO 3 ? , is an underrated regulating factor of soil N2O fluxes from cropland, especially in the regions where high NO 3 - leaching losses occur. 相似文献7.
Background and aims
Dominance of C4 grasses has been proposed as a means of increasing soil organic carbon (SOC) sequestration in restored tallgrass prairies. However, this hypothesis has not been tested on long time scales and under realistic (e.g. N-limited) environmental conditions. We sampled a restoration in southern Illinois 33 years after establishment to determine the effects of varying plant communities on SOC sequestration in the top 50 cm of soil.Methods
SOC, total nitrogen (TN), and the stable isotopic composition of SOC (δ13C) were used to calculate SOC sequestration rates, N storage, and the relative contributions of C3 vs. C4 plant communities as a function of soil depth.Results
While both a forb-dominated and a mixed forb-grass plant community showed positive sequestration rates (0.56?±?0.13 and 0.27?±?0.10 Mg C ha?1 yr?1, respectively), a C4 grass-dominated community showed SOC losses after 33 years of restoration (?0.31?±?0.08 Mg C ha?1 yr?1). Soil δ13C values were significantly more negative for forb-dominated plant communities, increasing the confidence that plant communities were stable over time and an important contributor to differences in SOC stocks among transects.Conclusion
These results suggest that functional diversity may be necessary to sustain sequestration rates on the scale of decades, and that dominance of C4 grasses, favored by frequent burning, may lead to SOC losses over time. 相似文献8.
Aims
The aim of this study was to investigate the effects of elevated CO2 concentration and nitrogen addition on soil organic carbon fractions in subtropical forests where the ambient N deposition was high.Methods
Seedlings of typical subtropical forest ecosystems were transplanted in ten open-top chambers and grown under CO2 and nitrogen treatments. The treatments included: 1) elevated CO2 (700?μmol?mol-1); 2) N addition of 100?kg NH4NO3 ha-1?yr-1; 3) combined elevated CO2 and N addition; and 4) control. We measured soil total organic carbon (TOC), particulate organic carbon (POC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC).Results
Results showed that elevated CO2 alone did not significantly affect soil TOC, POC and ROC after 4?years of treatment, but increased soil MBC and soil respiration compared to the control. N addition alone had no significant effect neither on soil TOC, POC and ROC, but decreased MBC and soil respiration over time. However, the elevated CO2 and N addition together significantly increased soil POC and ROC, and had no significant effect on soil MBC.Conclusions
This study indicated that even in N-rich subtropical forest ecosystems, inputs of N are still needed in order to sustain soil C accumulation under elevated CO2. 相似文献9.
Soil carbon dioxide and methane fluxes as affected by tillage and N fertilization in dryland conditions 总被引:1,自引:0,他引:1
Daniel Plaza-Bonilla Carlos Cantero-Martínez Javier Bareche José Luis Arrúe Jorge Álvaro-Fuentes 《Plant and Soil》2014,381(1-2):111-130
Background and aims
The effects of tillage and N fertilization on CO2 and CH4 emissions are a cause for concern worldwide. This paper quantifies these effects in a Mediterranean dryland area.Methods
CO2 and CH4 fluxes were measured in two field experiments. A long-term experiment compared two types of tillage (NT, no-tillage, and CT, conventional intensive tillage) and three N fertilization rates (0, 60 and 120 kg N ha?1). A short-term experiment compared NT and CT, three N fertilization doses (0, 75 and 150 kg N ha?1) and two types of fertilizer (mineral N and organic N with pig slurry). Aboveground and root biomass C inputs, soil organic carbon stocks and grain yield were also quantified.Results
The NT treatment showed a greater mean CO2 flux than the CT treatment in both experiments. In the long-term experiment CH4 oxidation was greater under NT, whereas in the short-term experiment it was greater under CT. The fertilization treatments also affected CO2 emissions in the short-term experiment, with the greatest fluxes when 75 and 150 kg organic N ha?1 was applied. Overall, the amount of CO2 emitted ranged between 0.47 and 6.0 kg CO2?equivalent kg grain?1. NT lowered yield-scaled emissions in both experiments, but these treatment effects were largely driven by an increase in grain yield.Conclusions
In dryland Mediterranean agroecosystems the combination of NT and medium rates of either mineral or organic N fertilization can be an appropriate strategy for optimizing CO2 and CH4 emissions and grain yield. 相似文献10.
Aims
Effects of different soil amendments were investigated on methane (CH4) emission, soil quality parameters and rice productivity in irrigated paddy field of Bangladesh.Methods
The experiment was laid out in a randomized complete block design with five treatments and three replications. The experimental treatments were urea (220 kg ha?1) + rice straw compost (2 t ha?1) as a control, urea (170 kg ha?1) + rice straw compost (2 t ha?1) + silicate fertilizer, urea (170 kg ha?1) + sesbania biomass (2 t ha?1 ) + silicate fertilizer, urea (170 kg ha?1) + azolla biomass (2 t ha?1) + cyanobacterial mixture 15 kg ha?1 silicate fertilizer, urea (170 kg ha?1) + cattle manure compost (2 t ha?1) + silicate fertilizer.Results
The average of two growing seasons CH4 flux 132 kg ha?1 was recorded from the conventional urea (220 kg ha?1) with rice straw compost incorporated field plot followed by 126.7 (4 % reduction), 130.7 (1.5 % reduction), 116 (12 % reduction) and 126 (5 % reduction) kg CH4 flux ha?1 respectively, with rice straw compost, sesbania biomass, azolla anabaena and cattle manure compost in combination urea and silicate fertilizer applied plots. Rice grain yield was increased by 15 % and 10 % over the control (4.95 Mg ha?1) with silicate plus composted cattle manure and silicate plus azolla anabaena, respectively. Soil quality parameters such as soil organic carbon, total nitrogen, microbial biomass carbon, soil redox status and cations exchange capacity were improved with the added organic materials and azolla biofertilizer amendments with silicate slag and optimum urea application (170 kg ha?1) in paddy field.Conclusion
Integrated application of silicate fertilizer, well composted organic manures and azolla biofertilizer could be an effective strategy to minimize the use of conventional urea fertilizer, reducing CH4 emissions, improving soil quality parameters and increasing rice productivity in subtropical countries like Bangladesh. 相似文献11.
Background and Aims
Soil contains many different C fractions which have diverse physical and chemical compositions. Examining these differential soil C fractions in response to N enrichment is helpful for better understanding soil C changes under the predominantly increasing N deposition. In this study, we used a field N addition experiment in a grassland to explore the effects of various N enrichment levels on soil C fractions.Methods
We conducted a field manipulative experiment which used a Latin square design with six N addition levels of 0, 2, 4, 8, 16 and 32 g N m?2 year?1 since 2003 in a semiarid grassland in northern China. Soil samples were collected in August (when plants have the greatest biomass), 2011. We measured C and N concentrations in soil light fraction, microbial biomass, extractable organic matter, heavy fraction, and total soil C and N.Results
The results showed that total soil C and N, and heavy fraction C and N were not significantly affected by N addition after 9 years of treatments. In contrast, different N enrichment levels changed soil light fraction C and N, ranging from 4.3 to 27.7 % and 3.3–30.0 %, respectively. Moreover, both light fraction C and N had a nonlinear relationship with N addition rates, and the threshold for N-induced change in light fraction C and N was near 16 g N m?2 year?1 in this semiarid grassland. Increases of soil light fraction C and N primarily resulted from changes in biotic (N-stimulated aboveground biomass) and abiotic (soil temperature, moisture and pH) factors under N enrichment. Soil microbial biomass exponentially declined with increasing N, but extractable organic C showed a positive linear response to N enrichment rates. Changes in microbial biomass C and extractable organic C were primarily due to the reduced soil pH under N addition.Conclusions
Our findings suggest that various soil C fractions differentially respond to elevated N, because different sets of biotic and abiotic factors regulate those fractions under N enrichment. 相似文献12.
Harvest residue management effects on tree growth and ecosystem carbon in a Chinese fir plantation in subtropical China 总被引:1,自引:0,他引:1
Zhiqun Huang Zongming He Xiaohua Wan Zhenhong Hu Shaohui Fan Yusheng Yang 《Plant and Soil》2013,364(1-2):303-314
Aims
This study aimed to determine the influence of different harvest residue management strategies on tree growth, soil carbon (C) concentrations, soil nitrogen (N) availability and ecosystem C stocks 15 years after replanting second rotation Chinese fir (Cunninghamia lanceolata), an important plantation species in subtropical China. Such information is needed for designing improved management strategies for reforestation programmes in subtropical environments aimed at mitigating CO2 emissions.Methods
Four harvest residue management treatments including slash burning, whole tree, stem-only and double residue retention were applied to sixteen 20 m?×?30 m plots in a randomized complete block design with four replicates. Tree growth was measured annually and soil properties were measured at 3 year intervals over a 15 year period after re-planting.Results
Cumulative diameter growth at age 15 years was significantly smaller in the slash burning than the whole tree and double residue harvest treatments. Hot water extractable N concentrations increased with the increased organic residue retention levels and significant differences were observed between double residue and slash burning treatments. Harvest residue management had no significant effect on the soil C concentrations to 40 cm depth. ANOVA showed that harvest residue management had no significant effect on total biomass carbon at age 15, but the plantation ecosystem (soil C at 0–40 cm depth plus forest biomass C) had significantly lower C mass in the slash burning treatment compared with whole tree, stem only harvest and double residue harvest treatments.Conclusions
These observations suggest that organic residue retention during the harvesting could improve the growth and ecosystem C stocks of Chinese fir in second rotation forest plantations in subtropical China and highlight the importance of viewing the ecosystem as a whole when evaluating the impact of harvest residue management on C stocks. 相似文献13.
Atmospheric nitrogen inputs and losses along an urbanization gradient from Boston to Harvard Forest,MA 总被引:1,自引:0,他引:1
Urbanization alters nitrogen (N) cycling, but the spatiotemporal distribution and impact of these alterations on ecosystems are not well-quantified. We measured atmospheric inorganic N inputs and soil leaching losses along an urbanization gradient from Boston, MA to Harvard Forest in Petersham, MA. Atmospheric N inputs at urban sites (12.3 ± 1.5 kg N ha?1 year?1) were significantly greater than non-urban (5.7 ± 0.5 kg N ha?1 year?1) sites with NH4 + (median value of 77 ± 4 %) contributing thrice as much as NO3 ?. Proximity to urban core correlated positively with NH4 + (R2 = 0.57, p = 0.02) and total inorganic N inputs (R2 = 0.61, p = 0.01); on-road CO2 emissions correlated positively with NO 3 ? inputs (R2 = 0.74, p = 0.003). Inorganic N leaching rates correlated positively with atmospheric N input rates (R2 = 0.61, p = 0.01), but did not differ significantly between urban and non-urban sites (p > 0.05). Our empirical measurements of atmospheric N inputs are greater for urban areas and less for rural areas compared to modeled regional estimates of N deposition. Five of the nine sites had NO 3 ? leached that came almost entirely from nitrification, indicating that the NO3 ? in leachate came from biological processes rather than directly passing through the soil. A significant proportion (17–100 %) of NO 3 ? leached from the other four sites came directly from the atmosphere. Surprisingly, the four sites where atmospheric sources made up the largest proportion of leachate NO3 ? also had relatively low N leaching rates, suggesting that atmospheric N inputs added to terrestrial ecosystems can move to multiple sinks and losses simultaneously, rather than being lost via leaching only after abiotic and biotic sinks have become saturated. This study improves our understanding of atmospheric N deposition and leaching in urban ecosystems, and highlights the need to incorporate urbanization effects in N deposition models. 相似文献
14.
Nathaniel B. Weston Scott C. Neubauer David J. Velinsky Melanie A. Vile 《Biogeochemistry》2014,120(1-3):163-189
Tidal wetlands are productive ecosystems with the capacity to sequester large amounts of carbon (C), but we know relatively little about the impact of climate change on wetland C cycling in lower salinity (oligohaline and tidal freshwater) coastal marshes. In this study we assessed plant production, C cycling and sequestration, and microbial organic matter mineralization at tidal freshwater, oligohaline, and salt marsh sites along the salinity gradient in the Delaware River Estuary over four years. We measured aboveground plant biomass, carbon dioxide (CO2) and methane (CH4) exchange between the marsh and atmosphere, microbial sulfate reduction and methanogenesis in marsh soils, soil biogeochemistry, and C sequestration with radiodating of soils. A simple model was constructed to estimate monthly and annually integrated rates of gross ecosystem production (GEP), ecosystem respiration (ER) to carbon dioxide ( \( {\text{ER}}_{{{\text{CO}}_{2} }} \) ) or methane ( \( {\text{ER}}_{{{\text{CH}}_{4} }} \) ), net ecosystem production (NEP), the contribution of sulfate reduction and methanogenesis to ER, and the greenhouse gas (GHG) source or sink status of the wetland for 2 years (2007 and 2008). All three marsh types were highly productive but evidenced different patterns of C sequestration and GHG source/sink status. The contribution of sulfate reduction to total ER increased along the salinity gradient from tidal freshwater to salt marsh. The Spartina alterniflora dominated salt marsh was a C sink as indicated by both NEP (~140 g C m?2 year?1) and 210Pb radiodating (336 g C m?2 year?1), a minor sink for atmospheric CH4, and a GHG sink (~620 g CO2-eq m?2 year?1). The tidal freshwater marsh was a source of CH4 to the atmosphere (~22 g C–CH4 m?2 year?1). There were large interannual differences in plant production and therefore C and GHG source/sink status at the tidal freshwater marsh, though 210Pb radiodating indicated modest C accretion (110 g C m?2 year?1). The oligohaline marsh site experienced seasonal saltwater intrusion in the late summer and fall (up to 10 mS cm?1) and the Zizania aquatica monoculture at this site responded with sharp declines in biomass and GEP in late summer. Salinity intrusion was also linked to large effluxes of CH4 at the oligohaline site (>80 g C–CH4 m?2 year?1), making this site a significant GHG source (>2,000 g CO2-eq m?2 year?1). The oligohaline site did not accumulate C over the 2 year study period, though 210Pb dating indicated long term C accumulation (250 g C m?2 year?1), suggesting seasonal salt-water intrusion can significantly alter C cycling and GHG exchange dynamics in tidal marsh ecosystems. 相似文献
15.
Pietro Panzacchi Giustino Tonon Christian Ceccon Francesca Scandellari Maurizio Ventura Marco Zibordi Massimo Tagliavini 《Plant and Soil》2012,360(1-2):229-241
Background and aims
Fruit orchards potential as carbon (C) sinks is virtually unknown. Moreover, despite their importance in the Mediterranean area, few data are available about the effect of the reduction in water availability on fruit tree productivity. Here we report the effect of two different irrigation regimes on net primary (NPP) and net ecosystem (NEP) productivities of an apple orchard in northern Italy in 2006.Methods
Trees productivity and heterotrophic soil respiration were estimated by inventory and root exclusion methods, while belowground allocation with a C mass-balance approach.Results
The NPP of the control (7.86?±?0.25?Mg?C ha-1; mean ± SE) was significantly greater than that of water stressed trees (6.53?±?0.12?Mg?C ha-1), and the ratio between above and below net primary productivity (ANPP/BNPP) was 1.88 and 0.98 respectively. However, the partitioning of ANPP and BNPP among aerial organs and among fine, coarse roots, and root litter was unaffected by the water regime. Although NEP was greater in the control than in stressed trees the C gain of the system after fruit removal (NEPafr) was unaffected by water availability.Conclusions
This study indicated an effect of water availability on C partitioning patterns above- and belowground, although there were no significant effects on the C sink potential as NEPafr. 相似文献16.
Plant growth regulator and nitrogen fertilizer effects on soil organic carbon sequestration in creeping bentgrass fairway turf 总被引:2,自引:0,他引:2
Rafael J. López-Bellido Rattan Lal Tom K. Danneberger John R. Street 《Plant and Soil》2010,332(1-2):247-255
The objective of this study was to determine the effects of plant growth regulator (PGR) (no PGR, trinexapac-ethyl, and paclobutrazol) and N fertilizer (zero N, an average of 37 kg N ha?1 month?1, 6 and 12 kg N ha?1 week?1) on soil organic C (SOC) and soil N in creeping bentgrass (Agrostis stolonifera L.) fairway turf. After 4 years of field experiments soil samples were obtained from soil depths of 0–2.5, 2.5–5, 5–7.5, 7.5–10, 10–15, 15–20, and 20–30 cm. Soil bulk density, SOC, total N, NO 3 ? –N, and NH 4 + –N concentrations were determined. Paclobutrazol and trinexapac-ethyl application increased SOC. The 37 kg N ha?1 month?1 application increased SOC at the 0–2.5 cm depth with both PGRs. When paclobutrazol was used, N fertilizer always increased SOC; however, the greatest increase was observed with the 12 kg N ha?1 week?1 application when compared to other rates, inversely related to the NH 4 + –N concentration. Nitrogen application increased soil total N and NO 3 ? –N in the upper three depths. The application of PGRs and N fertilizer to creeping bentgrass fairway turf is an effective strategy for promoting C sequestration. 相似文献
17.
Bernhard Zehetgruber Johannes Kobler Thomas Dirnböck Robert Jandl Rupert Seidl Andreas Schindlbacher 《Plant and Soil》2017,420(1-2):239-252
Aims
Slow or failed tree regeneration after forest disturbance is increasingly observed in the central European Alps, potentially amplifying the carbon (C) loss from disturbance. We aimed at quantifying C dynamics of a poorly regenerating disturbance site with a special focus on the role of non-woody ground vegetation.Methods
Soil CO2 efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration).Results
Total soil CO2 efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha?1 yr.?1). The undisturbed forest served as atmospheric C sink (2.1 t C ha?1 yr.?1), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (?5.5 t C ha?1 yr.?1) was almost twice as high as six years after disturbance (?2.9 t C ha?1 yr.?1), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss.Conclusions
C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.18.
Background and Aims
Rock fragments within topsoil have important effects on soil properties and plant growth. This study mainly aimed to investigate the relationships between rock fragments, soil carbon (C) and nitrogen (N) densities and vegetation biomass in an alpine steppe.Methods
Rock fragments, plant and soil samples were collected from four topographic positions (top, upper, lower, and bottom) on a hillslope.Results
Volumetric rock fragment content within the 0–30 cm soil profile varied from 17.8 to 30.5%, the upper position value was significantly greater (P < 0.05) than those at other positions. The highest aboveground biomass was observed at the lower position (921 kg ha?1), while the highest belowground biomass within the 0–30 cm profile was found at the upper position (4460 kg ha?1). More fine earth and plant litter input accompanied by lower C and N losses induced by rainfall erosion resulted in higher soil organic C and total N densities (28.6 Mg C ha?1 and 2.87 Mg N ha?1) at the lower position.Conclusions
Rock fragments may promote root growth but limit aboveground biomass production, and can therefore change the biomass distribution pattern. Our findings provide more evidence for scientifically assessing alpine steppe productivity.19.
Key message
Females of Populus cathayana allocated increased N to soluble proteins, while males keep N allocation pattern unchanged under N enrichment.Abstract
In our study, Populus cathayana as a model species is employed to detect the sex-specific responses in growth, photosynthetic nitrogen (N) use efficiency (PNUE), carbon (C) and N partitioning when exposed to 0, 7.5 and 15 g N m?2 year?1 on the basis of local N deposition level. Our results showed that females had higher responses in photosynthesis and growth than males when exposed to N deposition, and also exhibited higher PNUE than males when exposed to high level of N deposition, suggesting that plasticity in the females may enhance the capacity of young seedlings to acquire resources. Moreover, we found that females mainly allocated increased N to soluble proteins and detergent-soluble proteins, but not to cell-wall proteins, while males maintained original partitioning pattern of N and also accumulated excessive N in the form of free amino acids. Females also allocated more fraction of leaf N to carboxylation (P C), bioenergetics (P B), and then more fraction of leaf N to all components of photosynthetic machinery (P T) than males under high level of N deposition. Such sex-specific N allocation strategy may correlate with sex-related PNUE. These results indicated that there is a higher critical N demand in females, and females could use N nutrient more efficiently than males under high N deposition. We also found that higher shift from starch to soluble sugars, such as sucrose, occurred in females than in males under N enrichment. By contrast, excessive accumulation of starch and non-structural carbohydrate in females relative to males was observed under control conditions, which might inhibit female photosynthesis rate. Accordingly, we suggested that the different leaf C and N partitioning patterns could explain the sex-specific responses in growth. Therefore, females may obtain advantageous position in the process of intraspecific competition when exposed to high level of N deposition because they have higher light capture (total leaf area) ability and utilization efficiency (PNUE) than the males that confer the ability for fast growth and thus are likely to be more responsive to N enrichment. Our results suggested that it could be important to look at the stronger growth response of the females over the males under N enrichment at both the leaf and the plant scale. 相似文献20.