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作 者 ：张劲松,孟 平,高 峻,王鹤松,任庆福,贾长荣

期 刊 ：林业科学研究 2009年 22卷 6期 页码：807-812

关键词：杜仲人工林；蒸腾；相空间重建；分形；可预报性；

Keywords:Eucommia ulmoides plantation, transpiration, phase space reconstruction, fractal, predictability,

摘 要 ：以华北山地杜仲人工林为例,利用热扩散液流法测算得到的蒸腾数据,采用相空间重建法,在延滞时间(τ)为30 min条件下,分析林木蒸腾时间演变的分形特征及可预报时长,结果表明:林木蒸腾的时间演变过程具有分形和混沌特性,存在可预报性。2005年及2006年主要生长季节期间(4－9月),蒸腾时间序列的分形维数(D)分别是1.673和1.525, 二阶Renyi熵(K₂)分别为0.002 49和0.002 53,此时嵌入维数(m)分别为9和10,平均可预报时长(T)分别约为401.0 、394.8 min。尽管2005年和2006主要生长季节蒸腾的外表变化规律或数量等存在较大的差异,但在相同τ条件下,D和K₂在该2年间差异均很小,说明蒸腾时间序列的内在变化特征在不同年份间无差异。

Abstract:A case study with Eucommia ulmoides plantation in the mountainous region of North-China, predictability and fractal characteristics of temporal variation of trees transpiration were analyzed by using the method of reconstructing phase space when the lag time is 30 minutes. Transpiration measured with the technique of thermal dissipation probes in 2005 and 2006, The results showed that temporal variation of the plantation transpiration is a chaotic motion and characterized with fractal pattern and predictability during the main growth season. The fractal dimension (D), Renyi entropy (K₂), embedding dimensions and the average predictability time scale of time series for the trees transpiration were 1.673, 0.002 49, 9 and 401.0 minutes in 2005,respectively, and 1.525, 0.002 53, 10 and 394.8 minutes in 2006. There existed significant difference in external appearance of temporal variation or in the amount of transpiration between the two years, but no difference about D and K₂ at the same lag time. It is concluded that there were no differences in natural characteristics or internal patterns of time series in different years.

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