外生菌根真菌多样性对云杉根际土壤生化性质的影响

Effects of Ectomycorrhizal Fungal Diversity on Biochemical Properties of Spruce Rhizosphere Soil

【目的】探究是否由于地上宿主单一导致地下菌根真菌多样性低,进而减缓土壤有机质分解而导致较低的土壤养分有效性。【方法】将不同梯度多样性的外生菌根(ectomycorrhizas,ECM)真菌群落(1、2、4和8种外生菌根真菌)接种于栽植云杉幼苗的灭菌土壤(来源于川西亚高山云杉人工林),并设立对照组CK,1 a后测定根际土壤物理生化性质。【结果】接种4种ECM真菌土壤pH值(5.44)显著高于对照和其他处理(5.21~5.30)。土壤有机质和有机碳含量随ECM真菌接种多样性的增高呈下降趋势(有机质:37.62~22.81 g/kg;有机碳:21.82~13.23 g/kg),对照组有机质和有机碳含量显著高于8种外生菌根真菌接种组合处理组(P<0.05)。不同梯度多样性的外生菌根真菌群落接种对土壤全氮和全磷含量没有影响。土壤硝态氮(44.81~64.56 mg/kg)、无机氮(68.45~87.23 mg/kg)和可溶性全氮(341.28~483.72 mg/kg)含量有随着外生菌根真菌多样性的增加而增加的趋势,但4种外生菌根真菌接种处理除外(硝态氮29.68 mg/kg;无机氮49.65 mg/kg;可溶性全氮181.18 mg/kg),总体说明这4种真菌组合可能有利于宿主植物对氮的吸收,但不利于从有机质中活化氮组分。【结论】外生菌根真菌群落的多样性越高,可通过外生菌根真菌物种间的功能互补作用,越能促进有机质分解和提高氮可利用性。试验结果为菌根真菌多样性在西南亚高山土壤生态功能中的作用提供数据支撑和理论基础。

【Objective】 This study aimed to explore whether a single above-ground host plant can slow down the decomposition of soil organic matter by reducing the diversity of underground mycorrhizal fungi,and ultimately reducing the availability of soil nutrients.【Method】 In view of this,ECM fungal communities with different gradients of diversity(1,2,4,8 species of ectomycorrhizal fungi) were inoculated into the sterilized soil of Picea asperata seedlings(collected from the subalpine P.asperata plantation in southwest China),and the control(CK) was also established.After one year,the physical and biochemical properties of the rhizosphere soil were determined.【Result】 The results showed that the pH value of soil inoculated with four ECM fungi(5.44) was significantly higher than that of control and other treatments(5.21-5.30).The contents of soil organic matter and organic carbon decreased with the increase of ECM fungal diversity(organic matter,37.62-22.81 g/kg;organic carbon,21.82-13.23 g/kg).The contents of organic matter and organic carbon in the control were significantly higher than those in the eight ectomycorrhizal fungal inoculation groups(P<0.05).Inoculation of ectomycorrhizal fungi with different gradients of diversity had no effect on soil total nitrogen or total phosphorus contents.The contents of soil nitrate nitrogen(44.81-64.56 mg/kg),inorganic nitrogen(68.45-87.23 mg/kg),and total dissolved nitrogen(341.28-483.72 mg/kg) increased with the increase in the ECM fungal diversity,except for the inoculation of four species of ectomycorrhizal fungi(nitrate nitrogen,29.68 mg/kg;inorganic nitrogen,49.65 mg/kg;total dissolved nitrogen,181.18 mg/kg),suggesting that these four fungal combinations could facilitate the host-plant to acquire nitrogen,but are not conducive to the activation of nitrogen components from organic matter.【Conclusion】 The higher the diversity of the ectomycorrhizal fungal community,the stronger the effect on the decomposition of organic matter and the improvement of nitrogen availability.The results can provide data support and a theoretical basis for the role of mycorrhizal fungal diversity in soil ecological function in the southwest Subalpine region.