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题名	柽柳、梭梭林地土壤呼吸特征及影响因素研究
作者	朱宏
学位类别	博士
答辩日期	2008
授予单位	中国科学院．新疆生态与地理研究所
导师	赵成义，中国科学院新疆生态与地理研究所
关键词	土壤有机碳
其他题名	Studies of soil respiration and influencing factors in shrublands of Tamarix and Haloxylon ammodendron
中文摘要	土壤是个巨大的有机碳库，土壤碳库的微小变化可引起全球气候的显著变化。土壤呼吸是土壤释放CO2的过程，是土壤碳排放的方式之一。在占有全球陆地面积三分之一以上的干旱区，开展的土壤呼吸研究并不多，还缺乏足够的资料，因此在干旱区进行相关研究是十分必要的。干旱区的植被景观、土壤资源的空间分布具有斑块状的特点，植被的分布是构成这种分布模式的主要因素之一。在小生境范围内就可以完成植物碳－土壤碳的循环，造成干旱区林地土壤资源的空间分布差异。以新疆三工河流域为研究区域，以柽柳和梭梭林地作为研究对象，通过定位观测取样，运用地统计学方法，研究了柽柳、梭梭林地土壤呼吸、土壤微生物量、凋落物量的时空变化及其土壤理化因素，分析其灌木林地小生境尺度上的差异，从而揭示了柽柳、梭梭林地土壤呼吸特征及影响因素、生物碳的分布特征，为干旱区土壤碳循环研究提供依据。针对于上述内容，从上述各方面作了研究并得出如下结论： 1）土壤呼吸的季节变化明显，夏季高于春秋两季。气候条件对土壤呼吸的影响较明显，但是相对于其他因素（如C含量）来说，气候、管理等因素对土壤呼吸的影响较小。灌木植被对土壤呼吸有显著影响，灌木植物斑块状的分布特征使土壤呼吸值的高低分布也具有相同的特征，冠下土壤呼吸值高于灌间空地。土壤呼吸的大小受碳素限制较明显。回归土壤的植物凋落物增加了土壤的碳含量，成为决定土壤呼吸值高低的主要因素之一。干旱区土壤中的碳酸盐在土壤水溶液中的可逆反应可促使土壤呼吸的增大或减小，也是干旱区影响土壤呼吸大小的一个重要因素。 2）土壤微生物量受土壤水分、植物分布、气候因素等条件的影响较大，柽柳林地土壤微生物量呈中等变异性，变异系数最高值出现在柽柳冠下土壤中，在冠下0-10cm深土壤中最高土壤微生物量为1767μgg-1，微生物量从冠下向外围逐渐减小，具有很强的空间相关性。这种分布与土壤养分及水分分布的模式一致，均受到柽柳灌丛的影响。由于不同的生境条件，微生物群落也不相同，灌间空地低营养土壤中，细菌数量占优；在有机质相对较高的冠下土壤环境中，真菌占有量较大。干旱荒漠区土壤对MBC有盐胁迫和碳胁迫，土壤微生物量碳/土壤有机碳的比值为0.38％，表明MBC受盐分的影响严重。土壤微生物量在灌间空地垂直剖面上的分布与冠下分布不同。冠下表层的MBC高于表层以下；灌间空地则相反，10-20cm深的土壤微生物量高于0-10cm深土壤微生物量。 3）干旱区林地的凋落物量在年内呈单峰曲线变化，最高凋落物量出现在秋季。不同物种的凋落物量差异显著，柽柳凋落物量高于梭梭，柽柳凋落物量为1.138t/(hm2a)。土壤水分和大气湿度对凋落物量年际变化的影响较明显。凋落物分解速率在林地灌木冠下土壤和灌间空地土壤之间无显著差异，灌间空地20cm埋深凋落物在2个月时分解速率最大（0.0052g/d）。灌下与灌间两种生境中10cm埋深的凋落物分解速率下降的最快。影响凋落物分解的主要因素是凋落物本身的理化性质。 4）绿洲-荒漠交错带灌木林地中冠下与灌间空地的土壤质地差异显著。冠下的土壤生物资源条件好，更有利于植物生长，加剧了植物斑块分布格局的形成。灌间空地土壤盐碱化较重，抵制了冠下优势土壤资源的扩散，形成了灌木林地土壤资源和灌木一样呈现斑块分布。土壤水分与养分含量的分布与灌木的分布模式相同，从冠下向灌间空地逐渐减小的变化趋势。造成这种变化有土壤本身的因素，同时，植物种类的影响也比较明显，还有各种土壤因子的相互作用。柽柳对冠下土壤理化性质的影响要大于梭梭，前者更容易改善灌木周围及由上到下剖面深度的土壤要素含量。本文最后用Yasso模型尝试预测柽柳凋落物的分解及土壤碳的增加。在分解初期，凋落物碳损失较快，木质素含量高的凋落物碳转移很慢。凋落物经分解、转移而沉积的土壤碳增加很慢，有相当一部分凋落物碳以CO2气体的形式散溢到大气中了。Soil is a great carbon cool which varies slightly can cause the variation about globe climate. Soil respiration is a form of soil carbon release. The research about soil respiration is not more in the arid zone, and there is two thirds land is arid zone. It is necessary to research soil respiration in arid zone. The spatial distribution of soil resources are characteristics with patches, which resulted by vegetate distribution, as vegetation landscape in arid zone. The process of cycle from vegetation carbon to soil carbon, which result difference of spatial distribution in soil resources in a ecological niche in arid zone. The study sites, in this paper, are located in Sangong basin, with dominant plants of Tamarix ramosissima and Haloxylon ammodendron in Jungaar basin. The subject is carried out long time for two years by four aspects as soil characteristics in physic and chemistry, soil respiration, soil microbial biomass carbon and litter. The method of spatial statistic is applied to analyze the variations of the four aspects in temporal and spatial, influencing factors so done as biology carbon, and then explain their difference in ecological niche in scrublands. Thus we performance some studies and draw conclusions as following: 1) The variation seasonally of soil respiration is significant; soil respiration is higher in summer than spring and winter. The influence from air conditions on soil respiration is less than other factors as carbon content, thus factors of air conditions and management et al. are less effects on soil respiration. Vegetations are influent significantly on soil respiration. The soil respiration value under canopy is higher than outside and it is limited by carbon content in soil. The litters increase the carbon content in soil, which becomes a governing factor on soil respiration values. The carbonate in soil where has high soil moisture, can occur reversible reaction, the reversible reaction increase soil respiration value or not. 2) Soil microbial biomass carbon (MBC) is influenced by soil moisture, vegetation distribution, air conditions. MBC is middle grade variance, its highest value （1767μgg-1）occur under canopy soil（0-10cm）, the value decrease gradually from canopy to outside. MBC has intensive spatial correlation. Values of MBC have same spatial distribution as soil moisture, which influenced by Tamarix ramosissima. Microbial population is discrepancy in different ecological niche. Bacterial amount is higher in fertile soil and lower in barren soil. MBC suffer menace in salt and carbon. The value of MBC/SOC is 0.38% which indicates severe salt menace for MBC. MBC Under canopy soil is higher in surface than below surface; MBC outside is lower in surface (0-10cm) than below surface (10-20cm). 3) Litter biomass is a single peak curve in a year in arid zone, the highest value of litter biomass occurs in autumn. Litter biomass of Tamarix ramosissima is higher than Haloxylon ammodendron. Litter biomass of Tamarix ramosissima is 1.138 t/(hm2a). Soil moisture and air humidity influence significantly on annual litter biomass. Litter decomposition is not difference between under canopy and outside in shrubland, the litter decomposition is highest value (0.0052g/d) outside canopy 20cm depth in two months. In two niches ecological, litter decomposition at 10cm section is speedy; the main factor that influence litter decomposition is the properties of litter. 4) The differences, in soil texture between under the canopy and outsides, are significant in the shrublands of the oasis-desert ecotone. Soil resources under canopy, where prior to plant growing, are more fertile than outsides, which enhance the vegetation distribution in patches. The degree of salinity of soil under canopy is severe, which resist the diffusion in advantaged soil resources. So soil moisture and soil nutrients (SAN) have same distribution in patches, SAN are decreased from under the canopy to outside. Many factors can influence this distribution in SAN, including species of vegetation and interact between soil parameters. The impact for Tamarix ramosissima on soil properties in physics and chemistries under the canopy is greater than Haloxylon ammodendron, the former can improve easily the soil properties around the shrub. With a model of Yasso estimate the process of litter decomposition, litter carbon loss quickly in earlier period in litter decomposition. Litter carbon with high lignin amount loss slow. The increment of soil carbon from litter carbon is slow and part of litter carbon loss by carbon dioxide into atmosphere.
语种	中文
学科主题	植物生理学
公开日期	2010-11-12
页码	共107页
内容类型	学位论文
源URL	[http://ir.xjlas.org/handle/365004/8098]
专题	新疆生态与地理研究所_中国科学院新疆生态与地理研究所(2010年以前数据)
推荐引用方式 GB/T 7714	朱宏. 柽柳、梭梭林地土壤呼吸特征及影响因素研究[D]. 中国科学院．新疆生态与地理研究所. 2008.

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