發(fā)布時(shí)間：2018-11-04 09:45

【摘要】：為了解不同類型高寒草甸土壤碳氮穩(wěn)定同位素和密度的差異,采用穩(wěn)定同位素質(zhì)譜儀Isoprime100對(duì)采自黃河源區(qū)不同高寒草甸覆被條件下0~30cm土壤進(jìn)行了碳氮穩(wěn)定同位素組成特征和密度分析。結(jié)果表明,高寒草甸土壤δ13 C值介于-25.42‰~-24.20‰之間,δ15 N值介于3.37‰~4.69‰之間,顯著高于大氣δ15 N值。δ13 C值和δ15 N值均隨土壤深度加深而增大。人工草地土壤δ13 C值顯著低于輕度和重度退化草甸(P0.05),而δ15 N值顯著高于輕度和重度退化草甸(P0.05)。土壤碳氮比最小值為7.89,最大值為9.97,平均碳氮比為8.71。土壤有機(jī)碳含量和全氮含量呈正相關(guān)(P0.01),二者的回歸方程為y=0.0963x+0.0336(R2=0.9619)。輕度退化草甸、嚴(yán)重退化草甸和人工草地0~30cm土壤碳密度依次為7.14、6.67和6.46kg/m2;全氮密度依次為0.83、0.77和0.75kg/m2。植物吸收、生長(zhǎng)有利于12 C和14 N的輸出,而將較重的13 C和15 N留在了土壤中。人工草地植物生長(zhǎng)勢(shì)強(qiáng),形成的地上生物量多,吸收了較多的土壤氮素14 N,導(dǎo)致土壤15 N升高。植被退化或種植人工草地均可導(dǎo)致土壤碳氮密度的顯著降低,這種變化主要發(fā)生在0~20cm土層。
[Abstract]:In order to understand the differences of carbon and nitrogen stable isotopes and densities in different types of alpine meadow soils, Carbon and nitrogen stable isotopic compositions and densities of 0~30cm soils collected from different alpine meadow cover conditions in the source region of the Yellow River were analyzed by means of stable isotope mass spectrometer (Isoprime100). The results showed that the 未 13 C and 未 15 N values of alpine meadow soil ranged from -25.42 鈥，

本文編號(hào)：2309463