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生物结皮对荒漠草本植物生长生理特性和养分吸收的影响
庄伟伟
学位类型博士
导师张元明
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词生物土壤结皮 荒漠草本植物 生长生理特性 氮素传递 古尔班通古特沙漠
摘要生物土壤结皮是由蓝藻、荒漠藻、地衣、苔藓和土壤中微生物,以及相关的其它生物体通过菌丝体、假根和分泌物等与土壤表层颗粒胶结形成的十分复杂的复合体,与维管束植物覆盖一样,它是干旱区地表十分重要的微生态景观。生物土壤结皮在干旱区具有十分重要的生态功能,它影响着土壤物理过程、水文、侵蚀和养分循环过程,从而影响与之相邻的维管植物。尽管如此,目前有关生物土壤结皮和维管束植物之间相互关系的研究仍然很少且存在着争议。在中国西部古尔班通古特沙漠中生物土壤结皮对维管植物影响的研究主要集中在种子萌发和幼苗生长。然而,在干旱半干旱沙漠,生物土壤结皮对维管植物的影响可能还有其生理过程、养分吸收以及群落结构等方面。本文以新疆古尔班通古特沙漠为研究区,原位设置生物土壤结皮样地、去除生物土壤结皮样地和裸沙样地,探讨生物土壤结皮的存在对荒漠草本植物生长、生理过程、氮素运移与养分吸收以及群落结构的影响,这不仅能够填补该荒漠区域此项研究的空白,也能够为该荒漠生态系统潜在的植被演替方向提供重要的科学根据。所研究的植物包括尖喙牻牛儿苗(Erodium oxyrrhynchum)、条叶庭芥(Alyssum linifolium) 和硫苞菊(Hyalea pulchella)。 生物土壤结皮对三种荒漠草本植物生长的影响。研究结果表明生物土壤结皮对三种荒漠草本植物生长的影响在其整个生长期不同。在植物生长早期,生物土壤结皮的存在促进了三种荒漠草本植物生物量的累积;但是在生长后期,生物土壤结皮却显著抑制了其生长。与生物量在生长期逐渐递增的趋势不同,尖喙牻牛儿苗和条叶庭芥的冠根比(S/R)呈现先增加后减少的趋势。生物土壤结皮的存在显著影响了荒漠草本植物生物量的累积,却没有显著影响荒漠植物地上和地下生物量相关生长关系。三种荒漠草本植物在生物结皮区和去除生物结皮区下的地上、地下生物量是同速生长,与生物土壤结皮的存在没有显著关联。生物土壤结皮的存在影响了土壤水分和养分含量,土壤养分对于三种荒漠草本植物的早期生长是决定性的限制性因子,尤其是速效磷和速效钾。而土壤水分在植物生长早期却不是主要限制因子。但在植物生长后期,水分却代替养分成了影响植物生长的限制性因子。 生物土壤结皮对三种荒漠草本植物生理过程的影响。三种荒漠草本植物对生物土壤结皮的生理响应基本一致。生理过程研究结果显示,生长在生物土壤结皮区的尖喙牻牛儿苗、条叶庭芥和硫苞菊的叶片相对含水量(RWC)、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(E)、水分利用效率(WUE)、PSⅡ光化学效率(Fv/Fm)和PSⅡ量子产率(φPSⅡ)叶绿素含量在植物生长早期均高于生长在去除生物土壤结皮区的。但是,在植物生长后期,却是去除生物土壤结皮区的高。在整个植物生长期,生物土壤结皮的存在升高了三种荒漠草本植物体内可溶性糖、脯氨酸含量和过氧化物歧化酶、超氧化物歧化酶、过氧化氢酶活性,却降低了可溶性蛋白的含量。能够影响三种荒漠草本植物生长的因素可能也是影响其生理特性的因素。 生物土壤结皮对氮素传递和植物养分吸收的影响。氮素传递中选取荒漠地区广泛分布的短命植物尖喙牻牛儿苗为研究对象,研究生物土壤结皮和三种不同形式的氮同位素(15N-Glu, 15N-NH4Cl 和 15N-NaNO3)在其与土壤中的传递和吸收的影响。研究结果表明,随着与氮同位素施加点距离的增大,生物土壤结皮区和裸沙区尖喙牻牛儿苗和土壤中的15N均逐渐呈下降趋势。对于三种不同形式的氮素,生物土壤结皮区和裸沙区植物和土壤的吸收和聚集存在差异。相比于15N-NH4Cl 和 15N-NaNO3,生物土壤结皮区土壤中聚集了更多的15N-Glu。不同于生物土壤结皮区,裸沙区土壤却聚集了更多的无机氮。生物土壤结皮和裸沙区植物中吸收的15N-Glu显著高于15N-NH4Cl 和 15N-NaNO3。生长在生物土壤结皮区的尖喙牻牛儿苗比生长在裸沙区的吸收了更多的15N。同时,生物土壤结皮区的土壤也比裸沙区的土壤聚集了更多的15N。说明生物土壤结皮的存在有利于氮素的在土壤中的传递和植物的吸收。对于营养元素的吸收,生物土壤结皮的存在显著增加了三种荒漠草本植物对N和K的吸收,却对P的吸收没有显著影响。生物土壤结皮对三种荒漠草本植物对K、Ca、Mg、Na、Cl吸收的影响因种而异,对不同的植物有不同的影响。三种荒漠草本植物对C的吸收受生物土壤结皮影响较小,均未受到显著影响。 生物土壤结皮对植物群落结构的影响。生物土壤结皮使荒漠植物的群落组成结构发生了很大的改变。去除生物土壤结皮后,植被总密度明显下降。生物土壤结皮的存在没有显著影响植物的种数,生物土壤结皮区植物种数为7,去除生物土壤结皮后,植物种数仅增加了1。生物土壤结皮区的优势植物是尖喙牻牛儿苗,去除生物土壤结皮后,尖喙牻牛儿苗密度大大降低,条叶庭芥代替其逐渐在群落组成中占据优势。地上植被盖度、高度、生物量和物种多样性在两个样方中变化较大。生物土壤结皮区群落生物量和植被盖度均显著高于去除生物土壤结皮区的。尽管如此,与去除生物土壤结皮区相比,生物土壤结皮区植被的Shannon-Wiener多样性指数(H’)物种丰富度(R)和植被高度均显著较低。
其他摘要Biological soil crusts (BSCs; complex communities of cyanobacteria, algae, bryophytes, lichens and fungi aggregated with soil particles), the same with vascular plants coverage, are a common and widespread characteristic of soils in arid and semiarid climates throughout the world. As a particularly important component of desert ecosystem and landscape, BSCs widely distributed in many arid and semi-arid regions. They affect physical process, hydrology, soil erosion and nutrient cycle, thus affecting the adiacent vascular plants. Despite the importance of biocrusts in controlling water and nutrients, experimental evidence of their effects on vascular plant species is scarce and contradictory. In Gurbantunggut Desert, the largest fixed and semi-fixed desert in China, the previous relative research mainly focused on the seed germination and seeding growth. However, there are still many fields belong to the blank. In the present research, we attempted to experimentally investigate whether and how biocrusts affect desert vascular plant growth and physiological characteristics during different growing periods, nitrogen transformation and plant community structure in the Gurbantunggut Desert, looking forward to provide important scientific basis on the potential vegetation succession direction in this desert ecosystem. Three desert plant species, including Erodium oxyrrhynchum, Alyssum linifolium, and Hyalea pulchella. The effect of lichen-dominated BSCs on the growth of three desert vascular plants. The results showed that the effects of BSCs on the growth of three desert vascular plants were different during their whole growing period. The biomass and average leaf area of the three species in crusted soils were found to be higher than those in uncrusted soils in the early growth period and lower in the later part of the growing period. S/R of E. oxyrrhynchum and A. linifolium increased in the early growth period and decreased in the later part of the growing period. While BSCs did not significantly affect allometric scaling relationship, and all of the allometric relationship were isometric. The existence of BSCs affected soil moisture and nutrient content. Soil nutrient was the crucial limiting factor for plant growth in the early growing period, especially the available phosphorus and available potassium. However, water, instead of nutrient, was the crucial limiting factor in thelater growing period. The effect of lichen-dominated BSCs on the physiological characteristics of three desert vascular plants. The physiological response of three desert vascular plants to BSCs were identical. The results showed that leaf water content, photosynthesis(Pn),Stomatal conductance (Gs), transpiration rate (E), water use efficiency (WUE), PS Ⅱ photochemical efficiency(Fv/Fm), PS Ⅱ quantum yield(φPSⅡ)and chlorophyll content of the three species in crusted soils were found to be higher than those in uncrusted soils in the early growth period and lower in the later part of the growing period. Soluble sugar and proline contents and antioxidant enzyme activities were always higher in crusted soils than those in uncrusted soils. In contrast, soluble protein contents were always lower. The factors which affect the growth could also affect physiological process. The effect of lichen-dominated BSCs on 15N translocation and element uptake. In this experiment, the habitat-typical plant, E. oxyrrhynchum was chosen to evaluate the ecological roles of BSCs on N (including 15N-Glu, 15N-NH4Cl, and 15N-NaNO3) translocation from soil to plant in a temperate desert in China. The results showed that increased distance from the substrate application point led to a reduction in the concentration of δ15N in both E. oxyrrhynchum and in the soil. The concentration and uptake of three types of N isotope in soils and plants were different between crusted soils and bare soil. Soil covered by BSCs also accumulated considerably more 15N-Glu than bare soil; 15N-NH4Cl and 15N-NaNO3 served as key N source and dominated the allocation in bare soil. In two sites, the concentration of dissolved organic N (DON) (15N-Glu) in E. oxyrrhynchum was higher than that of dissolved inorganic N (DIN) (15N-NH4Cl and 15N-NaNO3). Plants of E. oxyrrhynchum growing in BSC covered plots accumulated more δ15N than those growing in bare soil. Our study supports the hypothesis that BSC facilitate 15N allocation in soil and vascular plants in a temperate desert of Northwestern China. BSCs also influenced nutrient uptake by plants, especially promoting uptake of N and K, while did not affect the uptake of P and C. The influence on uptake of other elements(K、Ca、Mg、Na、Cl) was species-specific. The effect of lichen-dominated BSCs on plant community structure. BSCs may be important in changing desert plant diversity. Vegetation density decreased obviously after the removal of BSCs. The existence of BSCs did not significantly influence plant species. Plant species increased only 1 after the removal of BSCs. The dominant species in BSCs site was E. oxyrrhynchum. However, the density of E. oxyrrhynchum decreased a lot after the removal of BSCs, and Alyssum linifolium became the dominant species. Community biomass and vegetation coverage in BSCs site were significantly higher than those in BSCs-removed site. In contrast, compared with BSCs-removed site, Shannon Wiener diversity index (H '), species richness (R) and vegetation height were significantly lower in BSCs site.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14622
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
庄伟伟. 生物结皮对荒漠草本植物生长生理特性和养分吸收的影响[D]. 北京. 中国科学院大学,2015.
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