北疆绿洲不同盐分浓度梯度下土壤的生物活性及其功能多样性

土壤盐分类型与含量对土壤生物活性和功能结构多样性会产生重要影响。本文模拟新疆北疆典型硫酸盐盐土,通过设置不同盐分浓度梯度(3、6、10、20和40 g kg-1),研究了土壤5种主要功能酶、土壤微生物量和土壤呼吸等生物性状的变化特征。结果表明:过氧化氢酶、蔗糖酶、β-葡萄糖苷酶和多酚氧化酶4种酶对盐分梯度响应非常敏感,其中过氧化氢酶、蔗糖酶和β-葡萄糖苷酶这3种酶活性与盐分浓度呈负相关,当盐分浓度达到40 g kg-1时,以上3种酶分别较对照降低25.7%、69.6%、30.0%;在3~6 g kg-1盐分浓度范围,多酚氧化酶随盐分浓度而升高,但在10~40 g kg-1时却显著降低,表现出"低盐促进,高盐抑制"的效应;纤维素酶对盐分浓度变化不敏感。土壤盐分与微生物量和微生物商呈显著负相关,与土壤基础呼吸和呼吸商则显著正相关,如40 g kg-1的盐分浓度导致土壤微生物量和微生物商分别较对照降低73.0%和69.5%,呼吸商升高了6.4倍。土壤过氧化氢酶、蔗糖酶、土壤微生物量、微生物商和呼吸商等可作为硫酸盐盐土早期预警生物指标。在40 g kg-1的含盐量下土壤生物功能结构明显区别于其他处理,且多样性指数显著下降。

Soil Biological Activity and its Functional Diversity along with Salinity Gradient in Oasis of Northern Xinjiang

Soil biological activities and its functional diversity could be significant impacted by soil salinity as well as soil salt type.In present research,a typical soil sulfate salinity gradients(3 g kg-1,6 g kg-1,10 g kg-1,20 g kg-1 and 40 g kg-1) simulated experiment was set up to study the characteristics of soil biological properties under different salinity levels in Xinjiang.The enzyme activities of Catalase,Invertase and β-glucosidase had a statistically significant negative correlation along with soil salinity gradients.In contrast with CK,soil enzyme activities of Catalase,Invertase and β-glucosidase decreased by 25.7%,69.6% and 30.0%,respectively,under salinity level of 40 g kg-1 treatment.Within soil salinity level range of 3-6 g kg-1,soil polyphenol oxidase activity increased with soil salinity increasing,however,that decreased with soil salt content increasing at soil salinity level range of 10-40 g kg-1.Enzyme activity of Cellulase was very tolerant to soil salinity was observed.Soil microbial biological carbon(MBC) and microbial quotient had a significant negative correlation with soil salinity,whereas,soil salinity showed a significant positive relationship with soil respiration and microbial respiration quotient(qCO2) as well.For instance,MBC and microbial quotient decreased by 73% and 69.5% respectively,and qCO2 increased by 6.4 times under the 40 g kg-1 treatment.From this results,the conclusion could be gotten that soil enzyme activities of Catalase and Invertase,MBC,microbial quotient and qCO2 were employed as useful indicators in term of soil salinization forewarning.Soil biological functional structure changed significantly when soil salt content increased up to 40 g kg-1,and soil functional diversity(Shannon diversity index) significantly decreased along with soil salinity gradient.