植被重建对黑土滩草地植被及微生物群落特征的影响

Effects of Vegetation Reconstruction on Vegetation and Microbial Community Characteristics of Black Soil Beach Grassland

为明确人为干扰对黑土滩草地植被及微生物群落特征的影响,以黑土滩退化草地和未退化嵩草草甸为对照,于2017年对果洛2015年、2012年、2009年、2006年建植的人工草地植被特征,土壤微生物碳、氮、磷含量,土壤微生物群落多样性和功能结构变化规律进行了研究。结果表明,(1)人工草地随建植年限增加地上生物量呈现先减少后持平的变化趋势,地下生物量则相反。(2)各草地土壤微生物碳、氮、磷均表现为0-10 cm显著高于10-20 cm的土层(P<0.05),0-20 cm土层中人工草地土壤微生物碳、氮、磷随建植年限呈现先增加后持平的趋势,其中2012年与2015、2009年人工草地差异显著(P<0.05)。(3)土壤微生物平均颜色变化率(AWCD)、H指数、D指数表现为0-10 cm显著高于10-20 cm(P<0.05)。培养2-5 d(AWCD)增长迅速,5 d后增长速率变缓;培养1 d H和D增长迅速,2 d后趋于平缓。(4)土壤微生物对6大类碳源利用情况显示,在0-10 cm土层中,微生物对脂类和羧酸类碳源的利用在不同草地间差异显著。人工草地随着建植年限的增加,对6类碳源的利用除醇类呈现无规律变化外,其余均呈“N”型变化趋势;在10-20 cm土层中,羧酸类、氨基酸类碳源利用在各草地间差异显著;人工草地随种植年限的增加除氨基酸类和胺类“N”型变化,其他草地均呈无规律的变化;Anosim分析显示,各草地土壤微生物群落功能结构有小差异,不同草地土壤微生物对31种碳源的利用种类及利用率存在差异。综上,建植5年后人工草地植被和土壤微生物趋于二次黑土滩退化,土壤微生物较草地植被能更早地作出指示,应采取持续合理的管护措施以维持人工草地的持久性。

To determine the effect caused by human disturbance on grassland vegetation and soil microbial community,the characteristics of vegetation,soil microbial biomass and community diversity,and other characters in the grassland,which were planted in 2015,2012,2009 and 2006 respectively,were studied in 2017 at Guoluo Prefecture in Qinghai Province.The results showed that,(1)The grassland aboveground biomass decreased first and then stayed the same with the increase of planting years,while the underground biomass had the opposite trend.(2)In all treaments,the soil microbial biomass carbon,nitrogen,and phosphorus at the soil depth of 0‒10 cm were significantly higher than that at 10‒20 cm(P<0.05).At the soil depth of 0‒20 cm,the soil microbial biomass increased first and then stayed the same with the planting years,significant difference were shown among 2012,2015 and 2009(P<0.05).(3)The soil microbial indexes such as AWCD,H and D of 0‒10 cm were significantly higher than those of 10‒20 cm.The growth rate of AWCD increased rapidly when cultured by 2‒5 days,and slowed down after 5 days;while the growth rate of H and D increased rapidly after 1 day of culture,then leveled off after 2 days.And(4)the utilization results of soil microorganisms to the six kinds of carbon sources showed that there were significant differences in the utilization of lipids and carboxylic acid carbon sources among different grasslands in the 0‒10 cm soil layer.With the increase of planting years,the utilization of soil microorganism to the six kinds of carbon sources showed a trend of“N”except for alcohols in artificial grassland.In the 10‒20 cm soil layer,the carbon source utilizations of carboxylic acids and amino acids were significantly different among various grasslands.With the increase of planting years,except for amino acid and amine“N”type changes,the other carbon sources were changed irregularly.Anosim analysis showed that there were small differences in the functional structure of soil microbial communities in different grasslands Soil microorganisms in different grasslands showed different utilization types and utilization rates to the 31 carbon sources.To sum up,the artificial grassland vegetation and soil microorganisms tend to the secondary black soil beach degradation after 5 years of construction;soil microorganisms can give instructions earlier than vegetation.Sustainable and reasonable management and protection measures should be taken to maintain the artificial grassland durability.