刈割对草原化荒漠区驼绒藜(Krascheninnikovia ceratoides)根际土壤特性的影响

在休眠期对草原化荒漠中自然生长的驼绒藜(Krascheninnikovia ceratoides)进行不同频度的刈割处理(连年刈割、隔年刈割、对照),通过测定根际土壤理化性质、土壤微生物数量及土壤酶活性等指标,分析和讨论了不同频度的刈割处理对驼绒藜根际土壤特性的影响。结果表明:(1)连年刈割和隔年刈割都显著提高了根际土壤含水量,隔年刈割使根际土壤全碳含量显著上升、有机质含量显著下降,但刈割对根际土壤pH值和全氮含量的影响不明显;(2)刈割对根际土壤微生物总量的影响不明显,但显著影响细菌、真菌和放线菌的组成,连年刈割使真菌数量显著增加,隔年刈割使放线菌数量显著增加,驼绒藜根际土壤中放线菌所占比例最大,其数量表征了土壤的贫瘠程度;(3)刈割对根际土壤过氧化氢酶和中性磷酸酶活性有显著影响,两种刈割处理会显著提高土壤过氧化氢酶活性、降低土壤中性磷酸酶活性,而对土壤多酚氧化酶、脲酶、转化酶和碱性磷酸酶活性的影响不显著。总之,隔年刈割对植物根际土壤养分供给及土壤分解者的活性更加有利,而且土壤理化因子对土壤微生物数量和土壤酶活性的影响不显著。刈割对驼绒藜根际土壤特性影响的规律性不强,可能是由于半灌木刈割利用的时间较短,根际土壤各个测量指标之间尚未形成显著的相关性。

Impacts of moving on the rhizosphere soil properties of Krascheninnikovia ceratoides in the steppe desert

Krascheninnikovia ceratoides not only serves as a good forage grass, but also creates a significant ecological barrier, which can maintain the stability of the desert-steppe ecosystem by effectively inhibiting soil erosion. Moving leads to compensatory plant growth and stimulates the secretion of carbohydrates from plant roots. Once the aboveground biomass of plant is damaged, its underground soil properties may change. Rhizosphere soil is of great importance because it serves as a microenvironment where plant, soil, and microorganisms can carry out nutrient cycling, the exchange of energy and the passing of information. Therefore, rhizosphere soil is strongly affected by plant roots and the activity of microorganisms. There currently is no research regarding moving on the rhizosphere soil properties of K. ceratoides. Therefore, a study of the impacts of moving on the rhizosphere soil properties of K. ceratoides could reveal the influence moving has on its underground biomass. Furthermore, it also can serve as a basic reference for putting K. ceratoides resources to rational use. In order to analyze the impacts of different moving frequencies on rhizosphere soil properties of K. ceratoides in the steppe desert, the soil physical and chemical properties, as well as the soil microorganisms and soil enzymatic activity, were investigated after different moving treatments (e.g., moving once a year, moving each year at a year interval) during the dormant period. Our results indicated that moving once a year and moving each year at a year interval significantly increased the rhizosphere soil moisture of K. ceratoides (P<0.05). Moving each year at a year interval resulted in significantly greater total soil C content, but lower soil organic matter content relative to the contrast (P < 0.05). However, neither the soil pH, nor the soil total N content was affected relative to the moving treatment. Moving had no significant influence on a total plate count of soil microorganisms, but significantly altered the composition of soil microorganisms including bacteria, fungi and actinomyces. The number of fungi significantly increased after moving once a year, while moving each year at a year interval significantly increased the number of actinomyces (P<0.05). Actinomyces were greater in number in the rhizosphere soil of K. ceratoides, representing some degree of soil impoverishment. Moving had a significant impact on soil hydrogen peroxidase and neutral phosphatase activity, but no significant influence was detected for soil polyphenol oxidase, urease, invertase, and alkaline phosphatase. Moving significantly increased the activity of soil hydrogen peroxidase, but reduced the activity of soil neutral phosphatase (P<0.05). In summary, moving each year at a year interval was more beneficial for rhizosphere soil nutrient supply and for the activity of soil decomposers. Furthermore, the soil''s physical and chemical properties had little effect on soil microorganisms and soil enzymatic activity. The effects of mowing on the rhizosphere soil properties of K. ceratoides were not strong, perhaps because the time of moving on subshrubs was not long enough to provide a significant correlation of each measurement indicator.