不同沙化程度草原地下生物量及其环境因素特征

为探讨草原沙化演替过程中地下生物量的变化规律,以内蒙古正蓝旗温性草原区为例,采用样地调查方法,研究了不同沙化程度草地地下生物量的垂直分布格局及其土壤环境特征。结果表明,1)草地地下生物量由土壤表层向深层急剧下降,总体呈“T”形分布,0~30 cm土层地下生物量占总地下生物量的80%以上;随着草原沙化程度的加剧,地下生物量呈显著下降趋势(P<0.05),未沙化草地、轻度沙化草地、中度沙化草地、重度沙化草地的地下生物量平均密度分别为2 598.67,2 318.45,390.26,117.25 g/m²。2)土壤温度随深度的增加而降低,30 cm以下土壤温度基本保持稳定;沙化草地深层土壤含水量略高于表层含水量,未沙化草地土壤保水能力优于沙化草地。3)在草原沙化演替进程中,土壤理化性质发生了一系列变化,与未沙化草地相比砂粒含量显著增加(P<0.05),沙化草地砂粒含量占90%以上;温性草原土壤pH值总体属于中性,各类型沙化草地间差异不显著(P>0.05);随着沙化程度的加剧,土壤有机质、全氮和速效氮含量均值较未沙化草地显著下降(P<0.05)。

Belowground biomass and features of environmental factors in the degree of grassland desertification

Belowground biomass is the important component of carbon accumulation on grassland, and the main link to relate aboveground with belowground ecosystem process. In order to discuss variation of belowground biomass in succession process of grassland desertification, taking grassland on Zhenglan Banner of Inner Mongolia as example, we analyzed its distribution pattern and soil environment features in different desertification grassland by the sample-plot survey method. We proceed with significance testing by one-way variance analysis (One-way ANOVA) and Scheffe method. The results showed that: 1) Belowground biomass decreased with soil depth and with a ‘T’ shape distribution. Belowground biomass in 0-30 cm soil layer occupied more than 80% of the total and then was significantly declined with the aggravation of grassland desertification (P<0.05). Belowground biomass of non-desertified grassland was the highest (2 598.67 g/m²), and was followed by slight desertified grassland (2 318.45 g/m²), moderate desertified grassland (390.26 g/m²) and severe desertified grassland (117.25 g/m²). 2) Soil temperature decreased with soil depth and remained stable under 30 cm soil layer. Soil moisture content of grassland desertification in deep soil layer was a little more than soil moisture content in surface layer. Water retaining capacity of non-desertified grassland preceded its desertified grassland. 3) Following succession process of grassland desertification, soil physicochemical properties occurred a series of variation. Sand content increased significantly compared with non-desertified grassland and occupied more than 90%. In general, pH value of soil on temperate grassland belonged to neutral. There was non-significant difference of pH value between the various types of desertified grassland (P>0.05). Following the aggravation of grassland desertification, soil organic matter, total nitrogen and available nitrogen content of desertified grassland were significantly lower than non-desertified grassland (P<0.05). The others nutrient content were non-significant difference. Through researching distribution pattern and soil environment features in different desertification grassland, this paper has provided effective data foundation and reference value with accuracy estimation of belowground biomass. Meanwhile, it has been the important significance to research distribution and gross of roots and enhance accuracy root module in model application.