沙蒿生物炭沙地封存生境效应及作用机理的研究

Artemisia is dominant plant populations in sandy land, which not only plays an important role in desertification control, but also has evident carbon sink functions. Cutting and stumping is in favor of rejuvenation of artemisia, furthermore, because of long-term stable characteristics of biological carbon in environment, it can develop ecological service function of sandy land when the cutting or dead artemisia is converted to biochar and sequestrated to the sandy land. The objects of this research and key scientific issues to be resolved are the effect of biochar of artemisia on sandy environment, including the effects on characteristic index of sandy land, the influencing mechanism, and so on, meanwhile, the biochar characteristic difference between Artemisia and other materials. The major contents studied are as follows: (1) effects of carbonization conditions including carbonization temperature and time and heating rate on biochar characteristic of artemisia, such as biochar yield, chemical composition, microstructure and spectral properties, and so on; (2) effect of artemisia on physical and chemical properties, biological properties and other environmental indexes of sandy land; (3) the relationship between environmental effects of sandy land and biochar properties of Artemisia, addition quantity of artemisia and artemisia application time. It can provide the basis for the preparation conditions established of artemisia biochar and effect of artemisia biochar on environement of sandy land according to the research results. .Artemisia is kind of super xeric psammophyte and its organization structure and chemical composition is different from straw or wood, therefore, the characteristic of this research is use artemisia as biochar materials. The innovative points of this study are effect of artemisia biochar on envirnement of sandy land due to the difference in properties between sandy land and cultivated soil. In Inner Mongolia, there is large regional area, while there are five species of Artemisia (Artemisia songarica Schrenk, A.wudanica, A.ordosica Krasch, A. sphaerocephala Krasch. and Artemisia ordosica Krasch.) distributed from the semi-humid region in the east to the extreme arid area in the west, therefore, the advantages and characteristics of resources can provide the necessary condition and sufficient conditions for this research.

沙蒿是沙地上生长的优势植物种群，对防沙固沙起着重要作用，同时也是特殊生境中的碳汇植物。沙蒿刈割有利于更新复壮，利用生物炭在环境中长期稳定的特性，将刈割或死亡的沙蒿转化为生物炭进行沙地封存，可以发挥沙地的生态服务功能。沙蒿生物炭沙地封存后对沙地生境产生何种影响，作用机理如何，是项目研究的目标。项目拟研究炭化条件对沙蒿特性的影响；沙蒿对沙地物理性质、化学性质、生物学性质的影响；沙蒿生物炭特性、沙蒿添加量、沙蒿施用时间与改沙效果的关系等内容。研究成果将为确立沙蒿生物炭制备条件提供依据，也为沙蒿生物炭对沙地生境效应的作用提供基础理论。由于生物炭制备材料的典型性和生物炭封存对象的特殊性，使本研究具备了特色和创新。内蒙古形成了自东向西不同干旱程度的沙地分布，沙蒿种类也从东到西形成由差不嘎蒿、乌丹蒿、褐沙蒿、油蒿、白沙蒿以至沙蒿逐渐替代的种群分布，这种资源优势和特点为项目研究提供了必要条件和充分条件。

项目背景 沙篙是恶劣生境下的重要碳汇植物，沙蒿平茬或刈割能够促其生长，如将刈割沙蒿就地转化为生物炭封存在固定或半固定的沙地，一方面可利用生物炭的稳定性实现碳汇的目的；另一方面利用生物炭多孔性、亲水性、吸附性等特性，实现改善沙地生境效应的目的。.研究内容 ①炭化温度、升温速率、炭化时间对沙蒿生物炭性质的影响；②沙蒿生物炭沙地封存对沙地生境的影响；③沙蒿生物炭性质、用量及施用时间与沙地生境效应的关系。.重要结果、关键数据及科学意义. 1．沙蒿生物炭性质受制备条件的影响。沙蒿生物炭孔隙发达、显碱性、含C量高，其理化性质受炭化温度和炭化时间的影响较大，受升温速率的影响相对较小。随着炭化温度的升高、炭化时间的延长，生物炭的P、K、Ca、Mg、C、CEC和粗灰分含量升高；pH值、总孔容、平均孔径和比表面积增大；而N、H、O、S含量和生物炭产率降低。本结果对不同利用目标生物炭的制备提供了技术依据。.2．沙蒿生物炭可以改变沙地生境。施用生物炭可以增加沙地有机碳、氮磷钾全量和有效量含量，提高了沙地CEC和pH值；促进沙地中脲酶、蔗糖酶、过氧化氢酶和碱性磷酸酶活性；使沙地微生物量C、N含量增加，本质是促进了细菌和放线菌的生长繁殖，但了抑制真菌，细菌主要增加了优势物种的数目和发育了Bacteroidetes和Caldithrix的新种属，而真菌主要是抑制了Ascomycota和Zygomycota种属。本结果说明，沙蒿生物炭具备提升沙地质量的作用，是沙产业发展中可利用的资源。.3.沙蒿生物炭性质、用量和施用时间对沙地生境效应均会产生影响。.炭化温度越高，炭化时间越长的生物炭，沙地碱解N含量越低，有效P、K含量和CEC越高；炭化温度为600℃，炭化时间为60min的生物炭在沙地中的保水效果最好，且能够极大的提高沙地的微生物量C、N含量，有助于提高沙地酶活性；炭化温度越高的生物炭越有利于细菌的生长繁殖而抑制真菌的生长繁殖。.沙地的全量养分、有效养分、CEC、微生物量C和N含量、pH、酶活性、微生物数量与生物炭施用量呈正相关；随着生物炭施用时间的延长，碱解N含量呈先升高后降低的趋势，有效P、K和CEC含量逐渐升高且随时间延长趋于稳定。. 上述结果揭示了沙蒿生物炭与沙地生境效应间的关系，是利用生物炭改沙治沙的理论研究。