南川百合与泸定百合种群格局关联维数的比较研究

Studies on the correlation dimensions of the distribution pattern among populations of Lilium rosthornii and Lilium sargentiae

本文采用分形理论中的关联维数比较分析了南川百合与泸定百合种群的空间分布格局及其分形特征。结果显示，南川百合与泸定百合种群的关联维数都不大（小于或接近1．5，比较远离2），说明其种群个体空间相关程度低，个体间竞争不激烈，种群整体对空间的占据能力不强，体现其在群落中的劣势伴生地位。在2006年，若只比较人为干扰小的种群，则南川百合5个种群的平均关联维数（1．1295）比泸定百合4个种群（1．5154）小25．46％；若不考虑人为干扰，在所有的样地中进行比较，那么，在2006年，南川百合5个种群的平均关联维数（1．1295）比泸定百合6个种群的（1．4496）小约22．08％，而在2005年，南川百合5个种群的平均关联维数（1．3671）也比泸定百合3个种群的（1．3673）要小一些，这些数据表明，与泸定百合种群相比，南川百合种群个体空间相关程度低，种群整体占据生态空间的能力弱。在高温干旱的2006年，这两种百合种群的平均关联维数与2005年相比都有所减少，但南川百合种群的平均关联维数的减少比例（17．38％）大于泸定百合的减少比例（6．26％），其减少比例约为泸定百合的2．78倍，这些数据表明，高温干旱天气会降低南川百合和泸定百合种群的适应能力，泸定百合的抗热抗旱能力要高于南川百合，南川百合更易受高温干旱天气的伤害。南川百合和泸定百合均出现濒危迹象，但因南川百合抗热抗旱性和占据生态空间能力更弱，导致其更加处于濒危状态．鉴此，应尽快在南川百合的主要分布区建立自然保护小区以保护其自然环境，同时与迁地保护相结合，并进一步探讨其濒危机制，以为这种百合的种质资源保护提供理论依据。

The fractal properties and spatial patterns of populations of Lilium rosthornii and Lilium sargentiae have been studied by the analysis of the correlation dimension. The correlation dimensions of populations of L. rosthornii and L. sargentiae were less than or near 1.5, far from 2, which indicates that the spatial autocorrelation among individuals was low, the competition among individuals was not intense, and the spatial occupation degrees of populations were not high, and that these populations were in an accompaniment position in these communities. In the year 2006, if only populations with less human-caused disturbance compared, the mean correlation dimension （1.1295） of the five L. rosthornii populations, compared with 1.5154 of the four L. sargentiae populations, decreased by 25.46%. If all the populations were compared without regard to human-caused disturbance, the mean correlation dimension 1.1295 of five L. rosthornii populations, compared with 1.4496 of the six L. sargentiae populations, decreased by 22.08% in 2006, while the mean correlation dimension 1.3671of this species was also less than 1.3673 of the three L. sargentiae populations in 2005, which suggested that the spatial autocorrelation among individuals and the spatial occupation degrees of L. rosthornii populations were lower than that of L. sargentiae populations. In the particularly drought year 2006 in Chongqing, the mean correlation dimensions of populations of L. rosthornii and L. sargentiae were lower than that in 2005 respectively, while the decrease percentage of 17.38% in the mean correlation dimension,of L. rosthornii populations, 2.78 times of that in L. sargentiae populations （6.26%）, was bigger than that of L. sargentiae populations. The data mentioned above indicated that the adaptation capacities of both species may be declined by the weather of high temperature and drought, and that hotness and drought resistances of L. sargentiae were stronger than that of L. rosthornii. Both L. rosthornii and L. sargentiae tend to be in an endangering condition, but L. rosthornii suffers more than L. sargentiae because of its lower capacities of hotness and drought resistances and low spatial occupation degrees. So nature reserve （spot） should be set up urgently to protect the nature environment of L. rosthornii in its main distribution area. The in-situ and ex-situ conservation prodedures should be done jointly. The endangered mechanism concerning the species should be further studied to provide theory base for the further conservation.