沙漠苔藓生物结皮层养分及颗粒组成特征

Nutrients and particle composition characteristics in moss biological crusts

探讨不同年份沙漠生物结皮层养分、颗粒组成的变化规律能够揭示流动风沙土的发育演变过程。文中主要采集了3个不同年份生物结皮层样本,并测定其养分含量和颗粒组成的变化。结果表明:和流动风沙土相比,13年、20年和40年生物结皮层有机质、全氮、速效磷、速效钾含量显著增加。苔藓结皮层有机质、全氮、全磷含量高于藻类结皮层。生物结皮层能够增加下层风沙土有机质、全氮含量,其影响深度通常为0-5cm,但随着生物结皮形成年份的增加,其影响深度可达20cm,甚至40cm。流动风沙土和生物结皮层颗粒中100μm-150μm和150μm^(-2)00μm粒径级平均含量分别为33.51%和33.32%。和流动风沙土比,随着年份增加生物结皮层颗粒100μm-150μm粒径级含量逐渐增加,特别是颗粒<2μm、<10μm、10μm-50μm和50μm-100μm粒径级含量均显著高于流动风沙土,说明生物结皮层土壤颗粒变细的趋势明显。苔藓生物结皮层对下层风沙土<10μm物理性粘粒影响深度为0-5cm。沙漠生物结皮层具有明显富集养分和细颗粒物的能力,并随着生物结皮层形成年份的延长,这种能力也逐渐增加。生物结皮层能够增加其下层风沙土养分和细颗粒物含量,改善风沙土理化性质,对风沙土发育演变过程具有积极作用。

Biological crust nutrients and particle composition of desert for different years can reveal the development and evolution of the shifting sandy soil as time goes on. In this study,we collected biological crusts for three different years and measured the nutrient content and particle composition. The results showed that organic matter,total nitrogen,available phosphorus,available potassium content in biological crusts of 13,20 and 40 years increased significantly compared with the shifting sandy soil. Organic matter,total nitrogen,total phosphorus contents of moss crusts were higher than algal crusts. Usually,biological crusts could increase the organic matter and total nitrogen content of the below sandy soil by 0-5 cm. However,as the time goes on,depth of nutrients that the biological crusts affected even reached 40 cm. 100μm-150μm and 150μm^（-2）00μm particles in shifting sandy soil and biological crusts particle were 33. 51% and 33. 32%,respectively. 100μm-150μm particles in biological crusts increased gradually as the years increases. Compared with the shifting sandy soil,the particles 2μm, 10μm,10μm-50μm and 50μm-100μm in biological crusts were significantly higher than that in shifting sandy soil,indicating the soil particles tend to became thinner in biological crusts. The sand layer depth that moss biological crusts affected the particles 10μm was of 0-5 cm. The desert bio-crust possessed the obvious ability to enrich nutrients and fine particles and the ability increased gradually with the formation of biological crusts. The bio-crust increased the nutrients and fine-particle content of the lower soil and also improved physical and chemical properties of sandy soil,biological crusts played an active role in the development and evolution of aeolian sandy soil.