荒漠地表生物土壤结皮形成与演替特征概述

土壤表面结皮是世界范围内干旱沙漠地区土壤表面广泛存在的自然现象,包括物理结皮和生物土壤结皮两大类型。其中,生物土壤结皮作为干旱沙漠地区特殊环境的产物,是由细菌、真菌、蓝绿藻、地衣和苔藓植物与土壤形成的有机复合体。它的形成使土壤表面在物理、化学和生物学特性上均明显不同于松散沙土,具有较强的抗风蚀功能和重要的生态效应,成为干旱沙漠地区植被演替的重要基础。随着形成生物土壤结皮的物种更替,维持结皮结构的主要胶结方式亦随之发生变化,即由胞外多糖的粘结作用逐渐转变为蓝藻和荒漠藻的藻丝体、地衣菌丝体以及苔藓植物假根的缠绕和捆绑作用,物种更替是结皮微结构和胶结方式转化的生物基础。生物土壤结皮的形成通常可以分为以下几个阶段:生物土壤结皮的早期阶段(土壤酶和土壤微生物),藻结皮阶段、地衣结皮阶段和苔藓结皮阶段。即随着土壤微生物在沙土表面的生长,随后出现丝状蓝藻和荒漠藻类植物,形成以藻类植物为主体的荒漠藻结皮;当土壤表面得到一定固定后,便开始出现地衣和苔藓植物,形成以地衣和苔藓植物为优势的生物结皮类型。其中,前一阶段的完成又为后一阶段的开始提供良好的环境条件。当环境条件适宜时,生物土壤结皮也可以不经历其中某个阶段而直接发育到更高级的阶段。     

腾格里沙漠不同生物土壤结皮微生物多样性分析

主要采用MiSeq技术对腾格里沙漠不同生物土壤结皮中微生物16S rRNA基因V4-V5区进行测序, 分析其细菌群落结构的组成、丰度以及多样性, 通过非度量多维尺度法和Venn图解释微生物群落结构对生物土壤结皮演化过程的响应。结果表明不同生物土壤结皮在门水平上主要以Proteobacteria、Actinobacteria和Cyanobacteria为优势类群; 结皮下流沙层在门水平上主要以Actinobacteria、Proteobacteria、Chloroflexi和Acidobacteria为优势类群。在OTUs组成上, 样品之间存在共同的微生物类群, 也存在差异的微生物类群。结皮下流沙层的微生物群落结构组成相似, 与结皮中微生物群落结构的组成差异较大, 且藻结皮和藓结皮中微生物类群差异明显, 说明微生物类群对生物土壤结皮的演化过程做出了环境响应。在从流沙向藻结皮到藓结皮的演化过程中, 放线菌(Actinobacteria)、蓝细菌(Cyanobacteria)和变形菌(Proteobacteria)对结皮形成、演化的生物地球化学循环过程发挥着重要的影响。结皮中不同微生物类群丰度的差异表明其对沙漠土壤环境变化的响应以及生态功能的不同。     

荒漠草原生物结皮演替对结皮层及层下土壤细菌群落结构的影响

为探明生物结皮演替对结皮层及层下土壤细菌群落结构的影响,采用空间代替时间序列的研究方法,以位于宁东能源化工基地的荒漠草原的不同演替阶段(藻结皮(ZB)、混生结皮(HB)和藓结皮(TB))的生物结皮和其下0～5 cm 土壤为研究对象,通过Illumina NovaSeq PE250平台对细菌16S rRNA的V3-V4高...     

中央戈壁石下生物土壤结皮固氮细菌群落结构和多样性

[背景]戈壁荒漠石下生物土壤结皮(Biological Soil Crusts,BSCs)由石下生物定殖繁衍而成,广泛存在于石英石下方,在相关生态系统的物质循环中起重要作用;其细菌群落结构受空间和土壤环境因子影响而变化较大.固氮细菌是石下BSCs的形成和发育主要驱动力;中央戈壁面积较大,为温带的代表戈壁之一,但目前其石...     

生物土壤结皮的生态功能

荒漠化土壤或多或少地存在着结皮现象 ,导致结皮的产生有物理、化学和生物的因素 ,其中由不同种类的苔藓、地衣、藻类、真菌以及细菌等生物组成成分与其下层很薄的土壤共同形成的一个复合的生物土壤层 ,也就是所谓的生物土壤结皮在荒漠地区最具生态意义。组成生物土壤结皮的藻类、苔藓和地衣是常见的先锋拓殖植物 ,不仅能在严重干旱缺水、营养贫瘠、生境条件恶劣的环境中生长繁殖 ,并且能通过其生活代谢方式影响并改变环境 ,在防风固沙、防止土壤侵蚀、改变水分分布状况等方面更是扮演着重要角色。土壤的生态演替过程 ,往往是组成物种由低等…     

不同植物群落下铜尾矿废弃地生物结皮中真菌群落结构的比较

分布于铜尾矿废弃地的裸地表面及维管植物群落中的生物土壤结皮在尾矿废弃地生态恢复过程中扮演重要角色。利用分子生物学技术探讨了不同维管植物下以及不同演替阶段的生物土壤结皮中真菌的多样性及其群落结构的变化。结果表明:生物土壤结皮中的真菌主要包括子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和壶菌门(Chytridiomycota),其中子囊菌门占绝对优势,其相对丰度为55.12%—87.73%,其次为担子菌门相对丰度为12.27%—43.86%;不同样本真菌群落结构在门、纲、目以及属的水平存在显著差异;生物土壤结皮中真菌群落结构和多样性的差异与维管植物群落类型以及演替阶段不同的生物土壤结皮的类型有关,与基质化学性质之间无显著的相关性。     

贺兰山东麓荒漠藻结皮微生物群落结构及其演替研究

以宁夏贺兰山东麓荒漠藻结皮为研究对象,对处于不同发育阶段的藻结皮中微生物群落结构及其演替进行了研究。结皮样品高通量测序结果分别得到521个16S rDNA序列操作分类单元(OTU)和64个18S rDNA序列OTU,表明藻结皮中原核微生物多样性远高于真核微生物;贺兰山东麓藻结皮中原核微生物分布于26个纲,Cyanobacteria在各个发育阶段中都是优势微生物类群,Actinobacteria、Chloroplast、Alphaproteobacteria和Bacilli在藻结皮发育的各个阶段相对丰度也较高;从属水平上分析,Bacillus、Leptolyngbya、Microcoleus、Microvirga、Chroococcidiopsis、Rubellimicrobium、Phormidium、Mastigocladopsis、Skermanella、Nostoc、Scytonema共11个属在各个发育阶段的藻结皮中都存在,只是出现了丰度的差异。Bacillus在藻结皮形成期、发育初期和发育中期相对丰度较大,成熟期丰度显著下降,而成熟期Microvirga丰度较前3个时期显著增...     

DGGE技术监测生物制氢反应器微生物群落结构和演替

为了研究生物制氢反应器微生物群落结构, 揭示混合菌群的生态学效能. 从连续流生物制氢反应器CSTR运行不同时期取活性污泥, 利用变性梯度凝胶电泳(DGGE)技术研究了产氢混合菌群的多样性和动态变化. 研究表明, 反应器从启动到乙醇型发酵稳定的运行, 经历了明显的微生物群落结构演替过程, 28天后反应器微生物群落结构基本恒定, 形成顶级群落. 16S rDNA 序列同源性分析表明, 优势种群为低G + C含量革兰氏阳性细菌分支的Clostridium sp.和Ethanologenbacterium sp., b变形菌亚纲的Acidovorax sp., g变形菌亚纲的Kluyvera sp.和一些未被培养的拟杆菌群的细菌和螺旋体. 21天后产氢细菌Ethanologenbacterium sp., Clostridium sp. (Clostridiaceae bacterium 80 Kb)和一些未被培养的螺旋体群细菌的数量明显增加, 形成乙醇型发酵群落, 产氢量大幅度提高. 群落经过演替微生物多样性增强后降低, 在群落演替过程中一直存在的Clostridium sp., sp., Kluyvera sp.和未被培养的拟杆菌群等是构成群落结构的基本种群, 混合菌群之间存在着共代谢作用, 共同决定产氢效能.     

短花针茅荒漠草原土壤微生物群落组成及结构

为详细了解内蒙古短花针茅荒漠草原生态系统中土壤微生物群落组成与结构。对其土壤中微生物的总DNA提取后,采用高通量测序技术对土壤中细菌的16Sr DNA和真菌的ITS基因进行了序列测定,分析了短花针茅荒漠草原土壤中微生物群落结构特征。结果表明,共获得细菌OTUs13711个,真菌OTUs 5929个。物种分类显示,细菌种类隶属于29门57纲111目191科485属,其中优势类群为Gammaproteobacteria和Thermoleophilia,它们的相对丰度分别为32.68%和26.83%。真菌隶属于4门16纲45目78科105属,优势类群为Ascomycota和Basidiomycota,它们的相对丰度分别为35.76%和25.90%。土壤中细菌群落的多样性和丰富度均高于真菌。     

胡杨土壤理化性质与微生物群落结构空间和分布的关系

土壤理化性质是微生物群落结构变化和空间分布的主要驱动力,揭示土壤与微生物之间关系是当前生态学和土壤学的研究热点之一。在大小胡杨树冠下少有植物生长的区域,测定距离树干不同位置（距离大胡杨树干0-3 m和3-6 m,距离小胡杨树干0-3 m,以及距离大小胡杨树干至少9 m以上;分别简写为DB_{0-3 m},DB_{3-6 m},DS_{0-3 m}和CK）的土壤理化性质和土壤微生物的群落组成,之后运用微生物群落组间差异分析、典范对应分析和Spearman相关分析等方法,探讨胡杨树冠下土壤理化性质与微生物群落分布组成之间的关系。结果显示：（1）在4个采样位置,细根生物量、土壤含水量、有机质、全氮、全磷和总盐均在DB_{0-3 m}最高,DB_{3-6 m}居中,DS_{0-3 m}和CK的含量最低（DB_{0-3 m}≥DB_{3-6 m}≥DS_{0-3 m}≥CK）（P<0.05）。DB_{0-3 m}的这些理化性质的含量分别是DS_{0-3 m}的3.97、1.13、3.71、3.03、1.49和1.95倍;相反,土壤容重在4个采样位置没有显著性差别（P>0.05）;（2）纲水平上,丰度排名前十的细菌和真菌分布组成在4个采样位置明显不同。细菌方面,Rhodothermia和γ-变形菌纲为DB_{0-3 m}的优势纲（相对丰度为0.27和0.28）,拟杆菌纲为其他3个位置的优势种（在DB_{3-6 m}、CK和DS_{0-3 m}的相对丰度为0.37、0.26和0.26）。真菌方面,粪壳菌纲为DB_{0-3 m}和DS_{0-3 m}的优势纲（相对丰度为0.27和0.10）。座囊菌纲为DB_{3-6 m}和CK的优势纲（相对丰度为0.09和0.16）;（3）细菌和真菌群落组成在4个采样位置存在显著差异。DB_{0-3 m}的真菌和细菌群落组成和DB_{3-6 m}较相似, DS_{0-3 m}和CK的真菌和细菌群落组成较为相似;（4）典范对应分析与Spearman分析结果表明,胡杨树冠下土壤微生物的群落组成受到土壤盐分、细根生物量、含水量、有机质、全氮和全磷的影响。其中,土壤盐分的影响最大。综合可知,在胡杨树冠下,土壤微生物群落的组成于胡杨树干下不同距离的位置上存在差异,它是胡杨和土壤之间物质交换、营养流动及微生物的生境选择共同作用的后果。土壤微生物群落组成在空间上的变化,可以负向影响树冠下幼苗的萌发和生长。在一定程度上,这种负向作用使得胡杨树冠下少有植物生长。     

生物结皮对3种荒漠草本植物光合生理特性的影响

通过人工去除生物结皮实验,研究古尔班通古特沙漠生物结皮对3种荒漠草本植物生理特性的影响,根据生物结皮对土壤养分和水分的影响,综合分析生物结皮对3种草本植物光合生理特性的影响。结果表明,生物结皮对3种荒漠草本植物光合生理的影响基本一致,在植物生长早期,生物结皮区的尖喙牻牛儿苗（Erodium oxyrrhynchum M.Bieb.）、条叶庭荠（Alyssum linifolium Steph.ex Willd.）和琉苞菊（Hyalea pulchella（Ldb.） C.Koch）的叶片相对含水量（RWC）、净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（E）、水分利用效率（WUE）、PSⅡ最大光化学量子效率（F_v/F_m）、PSⅡ实际光化学效率（φ_PSⅡ）和叶绿素（Chl）含量均高于去除生物结皮区;但是,在植物生长后期,却是去除生物结皮区的各项生理指标高。生物结皮对3种荒漠草本植物光合生理过程的影响与其对植物生长的影响基本一致,这与土壤养分和水分状况的变化密切相关。     

Recovery of lichen-dominated soil crusts in a hyper-arid desert

Soil crust lichens can be the dominant vegetation in desert regions that are unsuitable for higher plants, and are vital to soil stabilization and primary production. Biological soil crusts are vulnerable to disturbance and there is little evidence of the lichen components achieving full recovery following human disturbances in semi-arid to arid environments, and no records of recovery in hyper-arid deserts. Eight sites with varying anthropogenic, mechanical disturbance regimes were assessed in the hyper-arid Namib Desert for levels of recovery and successional convergence, based on a comparative analysis of overall lichen cover and community composition in disturbed and control locations. Recovery time estimations ranged from 5 to 530 years, with no detected linear relationship to impact gradient (low to high impact). Variables that were found to most strongly influence recovery rates were the overall cover of lichen growth and total number of lichen species in the bordering undisturbed areas, followed by the extent of soil compaction in the disturbed area, altered soil surface microrelief and vitality of subsurface soil crust components. An assessment of pioneering species demonstrated a link between increased soil depressions, i.e. track ruts, and the occurrence of fragmenting, wind-dispersing species. Track ruts in hype-arid deserts are not as vulnerable to the water erosion found in less arid deserts, and may be advancing recovery by trapping fragments. However, the lichen community structure was significantly different between all of the disturbed and control areas, regardless of the recovery phase, suggesting that while the lichen community composition may not. The ecological consequences of such disturbances may be far reaching in hyper-arid deserts where lichens are primary heterotrophs soil stabilizers. Given the economic development occurring within coastal hyper-acid deserts of the world, these impacts undoubtedly call for conservation attention.     

毛乌素沙地固碳功能菌群落随生物结皮发育阶段的演变特征

生物结皮是干旱区生态系统光合固碳的重要贡献者,固碳功能菌是生物结皮碳固定过程中的关键功能群,而毛乌素沙地生物结皮有关固碳功能菌群落多样性的研究未见详细报道。通过qPCR和高通量测序,研究了毛乌素沙地固碳功能菌基因丰度、群落多样性在生物结皮发育过程中的演变规律及其关键环境因子。结果表明,form IAB、IC和ID的基因丰度均随生物结皮发育呈升高趋势,在地衣结皮最高,在藓结皮又明显降低;form IAB的Chao1和form IC的Shannon指数随生物结皮演替呈显著上升趋势,而 form IC和ID的Chao1则在藻结皮达到峰值。物种组成上,IAB型固碳功能菌以蓝藻门的颤藻目占优势,其相对丰度在藻结皮最高,随生物结皮演替逐渐降低;IC型固碳功能菌在裸沙中以土壤红杆菌目为主, 而在三种生物结皮中以生丝微菌目、亚硝化单胞菌目和红螺菌目占优势; ID型固碳菌则以硅藻门的舟形藻目占优势,其丰度在裸沙中最高。IAB和IC型固碳功能菌群落结构在藻结皮和地衣结皮类似,而与裸沙和藓结皮差异显著,裸沙与藓结皮亦具显著差异。生物结皮演替过程中生物类群和土壤理化特征的改变为固碳功能菌提供了不同的生态位,土壤总有机碳、全氮、铵态氮、全磷、速效磷和pH对固碳功能菌群落进行综合调控,通过对固碳功能菌的筛选作用,最终改变固碳功能菌群落组成和结构。为深入理解荒漠生态系统生物结皮的光合固碳功能的微生物学机制提供了理论支撑。     

Population dynamics of Echinops gmelinii Turcz. at different successional stages of biological soil crusts in a temperate desert in China

• The effects of biological soil crusts (BSC) on vascular plant growth can be positive, neutral or negative, and little information is available on the impacts of different BSC successional stages on vascular plant population dynamics.
• We analysed seedling emergence, survival, plant growth and reproduction in response to different BSC successional stages (i.e. habitats: bare soil, cyanobacteria, lichen and moss crusts) in natural populations of Echinops gmelinii Turcz. in the Tengger Desert of northwest China. The winter annual E. gmelinii is a dominant pioneer herb after sand stabilisation.
• During the early stages of BSC succession, the studied populations of E. gmelinii were characterised by high density, plant growth and fecundity. As the BSC succession proceeded beyond moss crusts, the fecundity decreased sharply, which limited seedling recruitment. Differences in seedling survival among the successional stages were not evident, indicating that BSC have little effect on survival in arid desert regions. Moreover, E. gmelinii biomass allocation exhibited low plasticity, and only reproductive allocation was sensitive to the various habitats. Our results further suggest that the negative effects of BSC succession on population dynamics are primarily driven by increasing topsoil water‐holding capacity and decreasing rain water infiltration into deeper soil.
• We conclude that BSC succession drives population dynamics of E. gmelinii, primarily via its effect on soil moisture. The primary cause for E. gmelinii population decline during the moss‐dominated stage of BSC succession is decreased fecundity of individual plants, with declining seed mass possibly reducing the success of seedling establishment.

     

不同荒漠植物根际土壤微生物群落结构特征

于2015年7月在甘肃安西极旱荒漠国家级自然保护区采集膜果麻黄(Ephedra przewalskii)、红砂(Reaumuria songarica)、合头草(Sympegma regelii)、泡泡刺(Nitraria sphaerocarpa)和珍珠猪毛菜(Salsola passerina)5种典型荒漠植物根际土壤样品,利用磷脂脂肪酸(PLFA)法结合Sherlock微生物鉴定系统分析了土壤微生物群落结构。结果表明,5种荒漠植物根际土壤微生物磷脂脂肪酸种类和组成差异显著,其中表征革兰氏阳性菌的18:0 iso、16:0 iso和17:1 isoω9c分别为红砂、珍珠猪毛菜特有表征放线菌的18:1ω7c 10-methyl仅在珍珠猪毛菜根际存在。总PLFAs、真菌、放线菌和真菌/细菌在珍珠猪毛菜中显著最高,革兰氏阳性菌、革兰氏阴性菌在膜果麻黄和珍珠猪毛菜根际显著高于其他植物,AM真菌在合头草根际有最高值。结构方程模型分析表明,与植物相比,土壤因子对微生物群落结构影响更为显著,其中易提取球囊霉素对放线菌有显著影响,土壤碱解氮是革兰氏阳性菌和革兰氏阴性菌的主要影响因子。同时,土壤微生物群落结构可用于检测不同荒漠植物根际微环境土壤退化状况。     

The effect of lichen‐dominated biological soil crusts on growth and physiological characteristics of three plant species in a temperate desert of northwest China

Biocrusts (biological soil crusts) cover open spaces between vascular plants in most arid and semi‐arid areas. Information on effects of biocrusts on seedling growth is controversial, and there is little information on their effects on plant growth and physiology. We examined impacts of biocrusts on growth and physiological characteristics of three habitat‐typical plants, Erodium oxyrhynchum, Alyssum linifolium and Hyalea pulchella, growing in the Gurbantunggut Desert, northwest China. The influence of biocrusts on plant biomass, leaf area, leaf relative water content, photosynthesis, maximum quantum efficiency of PSII (F_v/F_m), chlorophyll, osmotic solutes (soluble sugars, protein, proline) and antioxidant enzymes (superoxide dismutase, catalase, peroxidase) was investigated on sites with or without biocrust cover. Biomass, leaf area, leaf water content, photosynthesis, F_v/F_m and chlorophyll content in crusted soils were higher than in uncrusted soils during early growth and lower later in the growth period. Soluble sugars, proline and antioxidant enzyme activity were always higher in crusted than in uncrusted soils, while soluble protein content was always lower. These findings indicate that biocrusts have different effects on these three ephemeral species during growth in this desert, primarily via effects on soil moisture, and possibly on soil nutrients. The influence of biocrusts changes during plant development: in early plant growth, biocrusts had either positive or no effect on growth and physiological parameters. However, biocrusts tended to negatively influence plants during later growth. Our results provide insights to explain why previous studies have found different effects of biocrusts on vascular plant growth.     

The influence of biological soil crusts on 15N translocation in soil and vascular plant in a temperate desert of northwestern China

Aims Desert ecosystems are often characterized by patchy distribution of vascular plants, with biological soil crusts (BSC) covering interplant spaces. However, few studies have comprehensively examined the linkage between BSC and vascular plants through nitrogen (N) or element translocation. The objective of this study was to evaluate the ecological roles of BSC on N translocation from soil to the dominant herb Erodium oxyrrhynchum Bieb. (Geraniaceae) in a temperate desert in China.Methods Isotopes (including 15 N-Glu, 15 N-NH 4 Cl and 15 N-NaNO 3) were used as a tracer to detect translocation of N in two types of desert soil (BSC covered; bare) to the dominant herb E. oxyrrhynchum. Three different forms of 15 N-enriched N compounds were applied as a point source to small patches of BSC and to bare soil. And we measured isotopes (14 N and 15 N) and obtained the concentration of labeled- 15 N in both vascular plants and soils at different distances from substrate applicationImportant findings Plants of E. oxyrrhynchum growing in BSC-covered plots accumulated more δ 15 N than those growing in the bare soil. Similarly, soil from BSC-covered plots showed a higher concentration of labeled-N irrespective of form of isotope, than did the bare soil. The concentration of dissolved organic N (15 N-Glu) in E. oxyrrhynchum was higher than that of dissolved inorganic N (15 N-NH 4 Cl and 15 N-NaNO 3). Soil covered by BSC also accumulated considerably more dissolved organic N than bare soil, whereas the dominant form of 15 N concentrated in bare soil was dissolved inorganic N. Correlation analysis showed that the concentration of labeled-N in plants was positively related to the concentration of labeled-N in soils and the N% recorded in E. oxyrrhynchum. Our study supports the hypothesis that BSC facilitates 15 N translocation in soils and vascular plants in a temperate desert of northwestern China.     

温带荒漠灌丛和藓类结皮对土壤养分的贡献

灌丛与生物土壤结皮镶嵌分布是温带荒漠常见的地表景观之一,二者的发育均显著影响了地表土壤养分的空间分布特征及循环过程。然而,灌丛和生物土壤结皮对荒漠土壤表层养分的影响存在怎样的差异,二者对养分变化的贡献度如何尚不清楚。因此,选择中国北方典型温带荒漠古尔班通古特沙漠为研究区,以荒漠中的优势灌丛膜果麻黄(Ephedra przewalskii)灌丛和生物土壤结皮发育高级阶段的藓类结皮的结皮层及结皮下层土壤为研究对象,采集不同微生境(裸露地、灌丛下)的裸沙与藓类结皮的土壤样品。为探究不同微生境下不同土层碳、氮、磷和钾养分变化特征,测定了不同土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、速效氮(AN)、速效磷(AP)和速效钾(AK)含量。结果表明:(1)相较于裸露地,灌丛显著提高了藓类结皮不同土层有机碳、全氮和全钾的含量和裸沙全磷的含量,降低了灌丛下藓类结皮土壤全磷的含量。(2)对于速效养分而言,与裸沙相比,裸露地藓类结皮覆盖降低了土壤速效氮含量,增加了速效磷和速效钾含量;而灌丛下藓类结皮覆盖提高了土壤速效氮和速效钾的含量,但降低了速效磷的含量。 (3) 相关性分析显示,在0-2 cm土壤中速效磷与速效氮呈现显著负相关,而在2-6 cm速效磷与速效氮呈现显著正相关(P<0.01)。(4)贡献度分析表明,土壤中灌丛效应对养分的贡献(42.54%)要远大于藓类结皮的贡献(2.43%),但二者交互作用却降低了除速效氮以外的其他土壤养分含量。综上,灌丛、藓类结皮覆盖和土层深度变化对土壤碳、氮、磷和钾养分均具有显著影响(P<0.05),但三者间的交互效应对养分的影响不显著(P>0.05)。相对于裸露地,灌丛与藓类结皮的覆盖均对表层土壤碳、氮、磷和钾养分具有促进作用,且随着土层深度的下降,土壤养分含量呈现显著的下降趋势(P<0.05)。因此,在荒漠生态系统中耐旱灌丛与生物土壤结皮这两个最重要的斑块单元联合调控了微尺度土壤养分的空间异质性变化。     

古尔班通古特沙漠生物土壤结皮对土壤氮库垂直分布特征的影响

生物土壤结皮在干旱区氮素地球化学循环中具有重要作用,研究不同生物土壤结皮下不同形态氮素含量的变化,解析生物土壤结皮对土壤养分影响过程和范围,有助于进一步理解生物土壤结皮的生态功能。本研究以古尔班通古特沙漠藻-地衣混生结皮和藓类结皮两种生物土壤结皮为研究对象,以裸沙为对照,测定生物土壤结皮层和0—100 cm内8个土层全氮、无机氮、可溶性有机氮、游离态氨基酸氮、微生物生物量氮等氮库含量,和土壤脲酶、硝酸盐还原态酶、亮氨酸氨基肽酶等土壤胞外酶活性。结果表明：1)结皮层各形态氮素含量和各土壤酶活性显著高于其下层土壤,结皮层和结皮下各层土壤氮库整体上表现为藓类结皮>藻-地衣混生结皮>裸沙;土壤氮库各形态氮素含量和土壤酶活性在垂直分布上均呈现先显著下降(0—20 cm)后稳定(20—100 cm)的趋势;在20—30 cm土层,除裸沙的无机氮、铵态氮以及藻-地衣混生结皮的硝态氮外,其余速效氮(无机氮、硝态氮、铵态氮)含量具有增加的特点。2)土壤各氮库含量与全磷、有机碳、电导率、土壤脲酶和亮氨酸氨基肽酶活性呈正相关,与pH、土壤含水率呈负相关。3)利用氮循环相关指标建立土壤氮循环多功能...