Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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Effects of P addition on plant C:N:P stoichiometry in an N-limited temperate wetland of Northeast China
No full textPhosphorus (P) enrichment induced by anthropogenic activities results in modified plant nutrient status, which potentially alters the stoichiometry of carbon (C), nitrogen (N), and P in plants. However, how increased P availability changes plant C:N:P stoichiometry at different hierarchical scales is unclear in N-limited ecosystems. In this study, we conducted a four-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m(-2) year(-1)) to elucidate the effect of P enrichment on plant C:N:P stoichiometric ratios at both the species and community levels in a freshwater wetland in the Sanjiang Plain, Northeast China. We found that species- and community-level plant C:N:P stoichiometry responded consistently to six years of P addition, although there was a shift in species dominance. Phosphorus addition increased plant N and P concentrations and thus decreased C:N, C:P, and N:P ratios irrespective of the P addition levels. These similar change trends at different scales resulted from the identical responses of plant N and P concentrations in different species to P addition. Moreover, plant N concentration exhibited an increasing trend with increasing P addition levels, whereas plant C:N ratio showed a declining trend. At the community level, P addition at the rates of 1.2, 4.8, and 9.6 g P m(-2) year(-1) decreased the C:N ratio by 24%, 27%, and 34%; decreased the C: P ratio by 33%, 35%, and 38%; and decreased the N:P ratio by 12%, 10%, and 6%, respectively. Our results indicate that the stoichiometric responses to P addition are scale-independent, and suggest that altered plant C:N:P stoichiometry induced by P enrichment would stimulate organic matter decomposition and accelerate nutrient cycles in N-limited temperate freshwater wetlands. (C) 2016 Elsevier B.V. All rights reserved
The Health Impacts of Dissolved Iron Impulse in Drinking Water Resources after Extreme Precipitation
No full textPhysiological Responses of Alfalfa to High-level Salt Stress: Root Ion Flux and Stomatal Characteristics
No full textAlfalfa is an important salt-tolerant leguminous forage-plant in salinity areas worldwide, but its performance in high level of salt stress cannot meet the satisfactory requirement. Especially, the short-term response of alfalfa to high-level salt stress is still not clear. In the present study, thirty-day-old alfalfa Gongnong No. 1 (Medicago sativa L. cv. Gongnong No. 1) seedlings were exposed to NaCl treatments at concentrations of 0 (control), 50 (moderate level), 150 (high level), and 250 mM (extremely high level). Twenty-four hours after salt stress treatment, with the increase of NaCl level plant height was slightly decreased but both shoot biomass and root length were substantially declined to a dramatic extent. Also decreased was root K+ concentration. In contrast, both Na+ concentration and ratio of K+/Na+ showed increased trends. Root K+ flux was determined using non-invasive micro-test technique (NMT) around apical root tips, wherein a clear K+ influx was observed at the rate of about 0.5 nmol cm(-2) s(-1) under the condition without salt stress, while under salt stress at the rate of 2. 3 nmol cm(-2) s(-1) did occur K+ efflux. Accordingly, stomatal length and breadth and stomatal aperture breadth decreased with the increase of NaCl concentration, while stomatal aperture density increased with time in the first 24 h after NaCl treatment. In conclusion, as a species-specific test, alfalfa is sensitive to high-level salinity with NaCl concentrations above 150 mM in the first 24 h post salt-exposure. The key mechanism was found to be presented as the pressed stamatal conductance induced by K+-Na+ unbalance which was caused by root K+ efflux. (C) 2016 Friends Science Publisher
The positive impacts of irrigation schedules on rice yield and water consumption: synergies in Jilin Province, Northeast China
No full textFood and water security in China are inextricably linked to the development of regional economy, especially for regions with temporary or sustained water shortage such as Jilin Province in northeast China. Water-saving irrigation practices are therefore urgently sought to maintain sustainable growth in grain production. To improve knowledge of the effect of irrigation water level on rice yield and water-use efficiency (WUE), we conducted a field experimental study over two growing seasons in central Jilin. The irrigation experiment included four schedules: (1) traditional irrigation (CK), (2) shallow wet irrigation (T1), (3) intermittent irrigation (T2), and (4) controlled irrigation (T3). Soil test pits were used to estimate evapotranspiration and seepage. The study showed that T3 had the highest WUE (1.64kg/m(3)). However, the highest rice yield was found in T1 (9867kg/ha(1)) that achieved the second highest WUE (1.63kg/m(3)). Compared with CK, T1 and T3 consumed 7.3% and 36.1% less water, respectively. If adopted at the operational scale, these two schedules could help reduce the pressure of local surface water supply and the production costs significantly. The results gained from this study could also have relevant implication in developing an effective irrigation management for other high-latitude regions
Reviews and syntheses: Four decades of modeling methane cycling in terrestrial ecosystems
No full textOver the past 4 decades, a number of numerical models have been developed to quantify the magnitude, investigate the spatial and temporal variations, and understand the underlying mechanisms and environmental controls of methane (CH4) fluxes within terrestrial ecosystems. These CH4 models are also used for integrating multi-scale CH4 data, such as laboratory-based incubation and molecular analysis, field observational experiments, remote sensing, and aircraft-based measurements across a variety of terrestrial ecosystems. Here we summarize 40 terrestrial CH4 models to characterize their strengths and weaknesses and to suggest a roadmap for future model improvement and application. Our key findings are that (1) the focus of CH4 models has shifted from theoretical to site- and regional-level applications over the past 4 decades, (2) large discrepancies exist among models in terms of representing CH4 processes and their environmental controls, and (3) significant data-model and model-model mismatches are partially attributed to different representations of landscape characterization and inundation dynamics. Three areas for future improvements and applications of terrestrial CH4 models are that (1) CH4 models should more explicitly represent the mechanisms underlying land-atmosphere CH4 exchange, with an emphasis on improving and validating individual CH4 processes over depth and horizontal space, (2) models should be developed that are capable of simulating CH4 emissions across highly heterogeneous spatial and temporal scales, particularly hot moments and hotspots, and (3) efforts should be invested to develop model benchmarking frameworks that can easily be used for model improvement, evaluation, and integration with data from molecular to global scales. These improvements in CH4 models would be beneficial for the Earth system models and further simulation of climate-carbon cycle feedbacks
Two new species of Allonychiurus Yoshii, 1995 (Collembola, Onychiuridae) from eastern China, with a key to world species of the genus
No full textTwo new species, Allonychiurus zhejiangensis sp. nov. and Allonychiurus pseudokimi sp. nov., have been reported from eastern China. A. zhejiangensis sp. nov. is particular in the genus as having three pso on ventral side of the head. A. pseudokimi sp. nov. is similar to A. kimi, but they can be distinguished by the number of pso on ventral side of the head, the number of chaetae along axial line on Abd. I-II, the number of chaetae on ventral tube and the presence of basal lamella on unguiculus. A key to the known species of the genus all over the world is given accordingly
Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China
No full textThe effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter
Carbon Emission Trends of Manufacturing and Influencing Factors in Jilin Province, China
No full textThis paper constructed a carbon emission identity based on five factors:industrial activity, industrial structure, energy intensity, energy mix and carbon emission parameter, and analyzed manufacturing carbon emission trends in Jilin Province at subdivided industrial level through Log-Mean Divisia Index (LMDI) method. Results showed that manufacturing carbon emissions of Jilin Province increased 1.304 × 10~7 t by 66% between 2004 and 2010. However, 2012 was a remarkable year in which carbon emissions decreased compared with 2011, the first fall since 2004. Industrial activity was the most important factor for the increase of carbon emissions, while energy intensity had the greatest impact on inhibiting carbon emission growth. Despite the impact of industrial structure on carbon emissions fluctuated, its overall trend inhibited carbon emission growth. Further, influences of industrial structure became gradually stronger and surpassed energy intensity in the period 2009-2010. These results conclude that reducing energy intensity is still the main way for carbon emission reduction in Jilin Province, but industrial structure can not be ignored and it has great potential. Based on the analyses, the way of manufacturing industrial structure adjustment for Jilin Province is put forward
Characterization of root-associated bacterial community structures in soybean and corn using locked nucleic acid (LNA) oligonucleotide- PCR clamping and 454 pyrosequencing
No full textThe community structure and diversity of root-associated bacteria have been tentatively investigated using polymerase chain reaction (PCR) amplification methods in several studies. However, the homology between small submit ribosomal (SSU) rRNA genes of plant plastids and mitochondria and that of bacteria have hindered in these studies. To address this issue, in this paper, we adopted the methods of locked nucleic acid (LNA) oligonucleotide-PCR clamping with 454 pyrosequencing to analysis the root-associated bacterial community compositions in soybean and corn. Results showed that plant chloroplast and mitochondria genes were effectively inhibited from PCR amplification in the root samples with LNA oligonucleotides (LNA (+)), and PCR amplicons with LNA (+) had higher bacterial operational taxonomic unit (OTU) numbers and ACE, Chao1, and Shannon indices, as well as a lower Simpson index than the corresponding samples without LNA oligonucleotides (LNA (-)). Those findings suggested that the methods of this study provide a much more detail description of root-associated bacterial communities. In the soybean LNA (+) sample, Pseudomonas, Bradyrhizobium and Flavobacterium were the three most abundant genera, whereas the top two predominant genera in corn LNA (+) samples were Streptomyces and Niastella. The presence and absence of major genera varied between soybean and corn, suggesting the root-associated bacterial communities differed between two crops. The rare phylotypes and uncultured root-associated bacterial members detected in this study inferred that the root-associated bacterial communities are highly complex and information on their taxonomic affiliates potentially gives the clues for selecting the optimal medium and method to isolate the novel bacteria for further functional analysis
吡嘧磺隆对稻田土壤真菌群落结构及土壤酶活性的影响
No full text采用PCR-DGGE和比色法,在室内培养条件下研究施用不同浓度吡嘧磺隆(0.4,4,40mg/kg)对土壤真菌群落结构及土壤酶活性的影响。结果表明:施用吡嘧磺隆7d时提高了土壤脱氢酶及多酚氧化酶活性,抑制葡聚糖酶活性,真菌多样性指数无明显变化;14d时,随着施药浓度的增大,脱氢酶活性减弱,多酚氧化酶活性增强,真菌多样性指数逐渐增大。21d时,随施用吡嘧磺隆浓度增大,土壤脱氢酶和多酚氧化酶活性会降低,而土壤葡聚糖酶恢复至对照水平,真菌多样性指数增大。试验结果为全面了解吡嘧磺隆对土壤微生态环境的影响提供数据依据