Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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黑土坡耕地秸秆覆盖对表层土壤结构和导气性的影响
No full text[目的]调查研究秸秆覆盖对黑土坡耕地表层土壤结构和导气性的影响,揭示秸秆覆盖措施对农田黑土土壤物理性状和功能的影响。[方法]利用黑土农田保护性耕作连续7 a的坡耕地长期定位田间试验,系统观测秸秆覆盖免耕处理和传统耕作处理的表层0-10 cm的土壤容重、孔隙度、饱和含水量、田间持水量和土壤导气率等指标,并加以分析。[结果](1)与秸秆移除传统耕作相比,秸秆覆盖免耕处理能够显著增加表层土壤容重、饱和含水量以及田间持水量,减少总孔隙度和非毛管孔隙度;(2)秸秆覆盖免耕处理使土壤水稳性团聚体显著增加,水稳性大团聚体(>0.25 mm)的含量、平均重量直径(MWD)和几何平均直径(GWD)分别提高了10.41%,45.28%和22.58%,且土壤表层导气性降低了30%。[结论]连续7 a的秸秆覆盖免耕改善了表层土壤团粒结构,增加了保水能力,但导气性较差
黄土高原半干旱区不同封育年限草地生态系统碳密度
No full text本研究以云雾山国家级自然保护区典型草原为研究对象,分析了不同封育年限长芒草(Stipa bungeana)草地生态系统碳密度及其库间分配规律。主要结果如下:放牧和封育5年、9年、15年、22年、25年、30年的草地生态系统碳密度变化范围为212.72~350.42Mg C·hm~(-2),其中,封育30年草地最高,放牧草地最低,且显著低于各封育草地(P<0.05)。草地植被碳密度以封育15年最高,达到15.65Mg C·hm~(-2),放牧草地最低,仅为7.82Mg C· hm~(-2)。在库间分配上,根系碳密度所占平均比例达到82.56%。草地土壤碳密度在204.90~337.36Mg C·hm~(-2)之间变化,随封育年限的延长持续增加,封育草地土壤碳密度是放牧牧草地的2.33~2.64倍。以上结果表明,封育可显著提高黄土高原半干旱区草地生态系统碳密度,但过长时间的封育阻碍草地的更新和固碳潜力发挥,合理利用才能促进草地生态系统持续健康发展
东北地区农业源一次颗粒物排放清单研究
No full text采用自下而上的清单编制方法,搜集各农业环节(秸秆燃烧、整地、收割、谷物处理、化肥施用、农机排放、风蚀)排放因子、作物面积和耕作方式等信息,编制了2010年东北地区县级尺度的农业一次颗粒物(PM_(10)和PM_(2.5))排放清单,并分析了农业源颗粒物排放的时空分布特征.结果表明:1)2010年东北地区农业源一次颗粒物PM_(10)总排放量54.6万t,PM_(2.5)总排放量35.6万t;2)东北地区农业源一次颗粒物PM_(10)排放量最大的农业活动环节是秸秆燃烧,占农业源总排放量的比例为60%,秸秆燃烧排放PM_(2.5)占PM_(2.5)农业源排放量的87%,整地环节是一次颗粒物排放的第2大农业排放源,对农业源排放PM_(10)和PM_(2.5)总量的贡献率分别是27%和6%; 3)PM_(10)和PM_(2.5)的排放强度空间分布表明,东北地区农业源颗粒物排放区域集中在黑龙江省东北部和中部地区,吉林省中部和辽宁省中部地区; 4)PM_(10)和PM_(2.5)排放的时间变化特征显示,PM_(10)农业源排放年变化曲线中,5月份和9、10月份是农业源排放一次颗粒物PM_(10)较多的月份,PM_(2.5)排放集中在9、10月份;5)本研究估算的污染物排放清单的不确定性为184.3%.未来的工作将侧重于典型农业区本土排放因子测定,从而有效减小排放清单的不确定性
大豆胞囊线虫主要寄生真菌对大豆耕作系统的响应
No full text大豆长期连作以后,随着土壤中大豆胞囊线虫的增多,胞囊线虫天敌也在不断积累,逐步形成大豆胞囊线虫抑制性土壤。真菌作为主要因子,在抑制性土壤中发挥重要作用。为探讨大豆长期连作对大豆胞囊线虫寄生真菌的影响,以大豆22年定位试验区为研究对象,分离和鉴定了22年大豆连作、3年大豆连作和22年大豆轮作(小麦-玉米-大豆)土壤和土壤中大豆胞囊线虫不同虫态寄生真菌。结果表明:大豆经过22年连作后,厚垣轮枝菌(Verticillium chlamydosporia)和淡紫拟青霉(Paecilomyces lilacinus)分离数量高于3年连作和22年轮作,其中厚垣轮枝菌的数量最高,每克土中含有1.5 × 10~4株,胞囊、卵和J2上分别分离到14, 18和8株,显著高于3年连作和轮作。研究结果证明了大豆经过长期连作后,土壤中积累了大豆胞囊线虫寄生真菌,而厚垣轮枝菌可能是抑制性土壤中的主要寄生真菌
Arbuscular mycorrhiza improve growth, nitrogen uptake, and nitrogen use efficiency in wheat grown under elevated CO2
No full textEffects of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis on plant growth, carbon (C) and nitrogen (N) accumulation, and partitioning was investigated in Triticum aestivum L. plants grown under elevated CO2 in a pot experiment. Wheat plants inoculated or not inoculated with the AM fungus were grown in two glasshouse cells with different CO2 concentrations (400 and 700 ppm) for 10 weeks. A N-15 isotope labeling technique was used to trace plant N uptake. Results showed that elevated CO2 increased AM fungal colonization. Under CO2 elevation, AM plants had higher C concentration and higher plant biomass than the non-AM plants. CO2 elevation did not affect C and N partitioning in plant organs, while AM symbiosis increased C and N allocation into the roots. In addition, plant C and N accumulation, N-15 recovery rate, and N use efficiency (NUE) were significantly higher in AM plants than in non-AM controls under CO2 enrichment. It is concluded that AM symbiosis favors C and N partitioning in roots, increases C accumulation and N uptake, and leads to greater NUE in wheat plants grown at elevated CO2
Assessing the conservation effectiveness of wetland protected areas in Northeast China
No full textThe evaluation of conservation effectiveness for wetland protected areas (WPAs) is essential to underpin knowledge-based conservation policies and funding decisions by government and managers. In this paper, the conservation effectiveness for 28 WPAs in Northeast China from 2000 to 2012 was quantitatively evaluated using landsat thematic mapper image data and a maximum entropy model (Maxent). The spatial distribution of conservation effectiveness and the influence of human activities on conservation effectiveness were determined by combining a landscape development intensity (LDI) index and spatial analysis in a geographical information system. The results showed that the natural wetland area of all WPAs in Northeast China declined by 11.5 % and the conservation effectiveness of most of these WPAs decreased between 2000 and 2012. A significant negative correlation between the LDI index and conservation effectiveness (r = -0.824, p < 0.01) suggested that human activities were responsible for the low conservation effectiveness of WPAs. The WPAs with the high conservation effectiveness were mainly located in the Da-Xing'an and Xiao-Xing'an Mountains, where anthropogenic activities were limited. The reduction in the conservation effectiveness of WPAs in the Songnen and Sanjiang Plains, which showed the most degradation, was due to conversion of wetlands to croplands. This research offers an efficient and effective method to evaluate the conservation effectiveness of WPAs. The results of this study will inform future ecological conservation and management of WPAs in China
Concentrations, sources, and export of dissolved CH4 and CO2 in rivers of the permafrost wetlands, northeast China
No full textThis study, conducted at the Emuer River in northern China during the growing season of 2014, investigated the concentrations and sources of dissolved CH4 and CO2 in wetland rivers in the permafrost region, as well as the total export of dissolved gaseous carbon (C) transported by streamflow. CH4 and CO2 concentrations in these rivers, ranging from 0.410-1.045 to 107.838-190.925 mu mol L-1, respectively, were among the highest levels of gaseous C concentrations reported from studies around the world. The concentrations of the C gases varied greatly with streamflow, but the influence of hydrological, as well as meteorological parameters, was not significant, except for the influence of the thaw depth of the soil active layer of adjacent wetlands on CH4 concentrations. delta O-18 parts per thousand values suggest the observed dissolved gases originated mainly from soil pore water in the active layers of the wetlands, as opposed to organic rich sediments in river beds, which serves as a common source for riverine CH4 and CO2 according to many other studies. A total of 444.30 t C was exported by the 3rd order main Emuer river during the growing season, and an export coefficient of 4.65 mg Cm-2 day(-1) was calculated for the wetland ecosystem. The dataset in this study is significant with regard to the global carbon balance because it is representative of the extensive wetlands occurring throughout the Eurasian permafrost. (C) 2016 Published by Elsevier B.V
DNA-binding protein phosphatase AtDBP1 acts as a promoter of flowering in Arabidopsis
No full textMain conclusion We provide evidence that AtDBP1 promotes flowering by regulating the transcript levels of several important integrators and floral meristem identity genes, including FLC, CO, SOC1, LFY, FT and FD. DNA-binding protein phosphatases (DBP) which exhibit both sequence specific DNA-binding and protein phosphatase 2C activities are important regulators that are involved in both the transcriptional and post-translational regulations. DBP factors are known to mediate susceptibility to potyviruses; however, whether they are involved in other processes is still unclear. In this study, under both long day (LD) and short day conditions, AtDBP1 overexpressing plants displayed early flowering, while the knock out mutants, atdbp1, exhibited a delay in flowering relative to the wild-type plants; both the overexpressing lines and atdbp1 mutants remained photoperiodic sensitive, indicating that AtDBP1 was involved in the autonomous pathway. AtDBP1 does not respond to vernalization at transcript level, and both AtDBP1 overexpressing plants and atdbp1 mutants remain responsive to vernalization, indicating that AtDBP1 may not be directly involved in vernalization. Real-time PCR analysis showed that AtDBP1 can suppress FLOWERING LOCUC C (FLC) expression, a key integrator of the autonomous and vernalization pathways, and enhance the expression levels of CONSTANS and FLOWERING LOCUC T, key regulators of the LD pathway. Furthermore, expression of floral meristem identity genes including SUPPRESSOR OF OVEREXPRESSION OF CO 1, LEAFY and FD was also promoted in AtDBP1overexpressing plants. AtDBP1 transcription can be detected in root, leaf, stem, flower and silique. AtDBP1-GFP and YFP-AtDBP1 fusion protein were localized in the cytosol and nucleus. Our results provide the evidence demonstrating the effective role of AtDBP1 for flowering time regulation and report a novel function of DBP factors in planta besides in plant defense