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为揭示水杉(Metasequoia glyptostroboides)原生母树种群的生存现状与数量动态,预测未来种群的发展趋势,基于野外种群调查数据,对种群结构与动态进行探讨。结果表明:(1)种群自然更新不良,DBH<40 cm的个体仅占种群个体总数的4.5%,纺锤型的径级结构表明种群属衰退型。(2)种群幼龄个体存活率较低,中龄个体生存能力强,Ⅷ龄级之后存活量快速减少,存活曲线接近Deevey-Ⅲ型;种群死亡率和消失率整体上都随龄级增大而升高,均在Ⅸ龄级达到最大值。(3)生存分析表明,种群呈前期略减、中期波动、后期衰退的特征;幼龄阶段是种群生活史中的脆弱环节,Ⅷ龄级之后种群进入生理衰退期。(4)时间序列预测表明,未来8年期间种群幼龄和中龄个体不断减少,老龄个体渐增,种群整体的长期稳定性难以维持。总之,幼龄个体严重缺乏是种群趋于衰退的主要原因,保持适当的人工辅助恢复和加强现有植株及其生境保护是种群更新复壮的关键。
In order to reveal the survival status and population dynamics of native tree populations of Metasequoia glyptostroboides and to predict the future trend of population development, population structure and dynamics were discussed based on field population survey data. The results showed that: (1) The population was naturally updated badly. Individuals with DBH <40 cm only accounted for 4.5% of the total number of individuals in the population. The diameter structure of spindle type indicated that the population was recession-type. (2) The survival rate of young individuals in the population was lower than that in the middle-aged individuals. The survival rate of the middle-aged individuals was very fast. The survival rate decreased rapidly after the age of the eighth instar and the survival curve was close to Deevey-Ⅲ. The mortality and disappearance rate of the population as a whole increased with age While increased, reaching the maximum in the age group of Ⅸ. (3) Survival analysis showed that the population was characterized by a slight decrease in the first period, a mid-term fluctuation, and a late decline. The young stage was a fragile part of the population life history, and the population entered the physiological decline stage after the Ⅷ stage. (4) The forecast of time series shows that the population of young and middle-aged individuals will decrease continuously in the next 8 years, the aging individuals will increase, and the long-term stability of population as a whole will be difficult to maintain. In short, the serious shortage of young individuals is the main reason for the population decline. It is the key to renewing and rejuvenating populations that proper artificial recovery and enhancement of existing plants and their habitat protection should be maintained.