为探讨尕海湿地退化过程中植被生物量变化规律,以尕海泥炭沼泽和沼泽化草甸为例,采用定位样地调查方法,研究了不同退化程度湿地植被生物量的时空分布格局.结果表明,1)随着湿地退化演替,两类湿地植被地上生物量逐渐减小,泥炭沼泽未退化(PI)、退化阶段(PⅡ)地上生物量依次为334.19,290.72 g/m2,沼泽化草甸未退化(SⅠ)、轻度退化(SⅡ)、中度退化(SⅢ)地上生物量依次为378.40,308.07,261.21g/m2;地上生物量季节动态规律均为单峰型,8月中下旬达到峰值;同一湿地类型各退化阶段地上生物量绝对增长率(AGR)和相对增长率(RGR)在同一年份变化趋势基本相同,但不同年份间存在差异,而同一湿地类型不同阶段AGR和RGR的大小存在差异.2)地下生物量也随退化程度加剧显著减小(P＜0.05),PⅠ,pⅡ地上生物量依次为23081.46,12607.72g/m2,SⅠ,SⅡ,SⅢ地下生物量依次为4583.16,3008.63,1290.73g/m2;地下生物量季节变化均表现出愈接近生长季始末值愈大;地下生物量由土壤表层向深层显著下降(P＜0.05),总体呈“T”形分布,0-10cm土层,泥炭沼泽、沼泽化草甸地下生物量都最大,分别占各自总地下生物量50％和70％以上.3)尕海2类高寒湿地5-9月平均根冠比均表现未退化高于退化,根冠比季节动态为越接近生长季始末值越大,生长旺盛季值越小.%Wetlands are important contributors to the global carbon (C) cycle because they store large quantities of C in their vegetation and soil and exchange CO2 actively with the atmosphere through photosynthesis and respiration.Plant biomass is a critical part of the primary production in wetland ecosystem that maintains the wetland health and quality.It also provides many ecosystem functions,such as C sequestration in alpine wetland.Therefore,biomass is the main link that relates aboveground and belowground ecosystem processes.We used the peatlands and swamp medows areas in the Gahai wedand of south Gansu province to investigate changes to plant biomass during degradation succession in an alpine wetland.The time-space distribution pattern of the area at different stages of wetland degradation was analyzed using the sample-plot survey method.Significance testing was conducted using one-way variance analysis (One-way ANOVA) and the Schaffer method.The results showed that 1) the aboveground biomass decreased gradually in the peatlands and swamp medows as degradation succession progressed.The reduction in aboveground biomass followed the order non-degraded peatlands (PⅠ) (334.19 g/m2) ＞degraded peatlands (PⅡ) (290.72 g/m2),and was non-degraded swamp meadows (SⅠ) (378.40 g/m2) ＞lightly degraded swamp meadows (SⅡ)(308.07 g/m2) ＞moderately degraded swamp meadows (SⅢ) (261.21 g/m2).The curves for the aboveground biomass seasonal dynamics for the two sites were seasonal dynamics of aboveground biomass was single apex types,the variation trends were the same,and they reached a peak value in August.The changes in the absolute growth rate and relative growth rate of aboveground biomass at each degradation stage on the same wetland types were consistent for each degradation stage on the same wetland types over the years the survey took places,but the values were different between years.The values for absolute growth rate and relative growth also varied depending on the degradation stage in the same wetland type.2)The belowground biomass decreased significantly in the two wetland types as degradation succession (P＜0.05).The belowground biomass in PⅠ was 23081.46 g/m2 and was 12607.72 g/m2 for PⅡ in the peatlands,and followed the order SⅠ (4583.16 g/m2) ＞ SⅡ (3008.63 g/m2) ＞ SⅡ (1290.73 g/m2) in the swamp meadow.The seasonal variations in belowground biomass for each wetland type were different,but the earlier the growing season began and ended,the greater was the amount of belowground biomass.Belowground biomass decreased significantly (P＜0.05) with soil depth and had a "T" shape distribution.The peat and swamp meadow belowground plant biomass was greatest in the 0-10 cm soil layer,and occupied more than 50％ and 70％ of their total belowground biomasses,respectively.3) The average root-shoot ratio for non-degraded wetland was higher than for degraded wetland between May and September.The root-shoot ratio seasonal dynamics showed that the earlier the growing season began and ended,the greater was the ratio,and the shorter the period of vigorous growth.These results provide a scientific basis for wetland planning and management and an accurate estimation of C balances in alpine wetland ecosystems.
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