坡位对乳白香青种群特征及雌雄株形态可塑性的影响

Impact on slope positionabout population characteristics and morphological plasticity of the dioecious herb Anaphalis lactea

为探究亚高山雌雄异株草本植物乳白香青(Anaphalis lactea)对生境的适应能力,通过对不同坡位乳白香青种群组成、个体构件性状、生物量结构及水分含量测定,研究坡位对乳白香青种群特征及雌雄株形态可塑性的影响。结果表明,坡位对乳白香青种群特征参数有显著影响(P<0.05),影响大小表现为性比>种群密度>年龄结构>种群数>分布系数>种群面积;坡底种群特征参数显著大于坡顶和坡腰,坡位越低种群衰退越慢而雌雄比更大。坡位显著影响构件性状(P<0.05),随坡位降低叶数减少,而叶长、叶宽和叶厚增加,株高和茎长显著增加,根长变长而根径变细;坡位对雌株叶数、叶长、叶宽、茎长、茎径、根长、花序数、花序宽、小花数及苞片宽的影响大于雄株,对雄株叶厚、根径、苞片层数影响大于雌株。坡位显著影响生物量结构(P<0.05),坡位对雌株根、茎、叶及花生物量分配有显著影响(P<0.05),对雄株根和茎分配有显著影响,对叶和花分配影响较小。乳白香青雌、雄株均可通过形态可塑性适应生境,使种群具有与坡位适应的性比、密度、年龄结构及分布系数等种群特征。

In the present study,the dioecious herb Anaphalis lactea,growing in different slope positions(top,middle,and bottom)of the same slope was analyzed.Population composition,individual characteristics,biomass structure,and water content were evaluated.The purpose was to analyze the influence of slope position on the population characteristics and morphological plasticity of A.lactea.The results showed slope position had significant effects on the population characteristics of A.lactea(P<0.05)in the following order:sex ratio>population density>age structure>population number>coefficient of distribution>population area.The population characteristics at the slope bottom are more than those at the mid and top slope significantly.The population decreased from the top to bottom slope and the sex ratio became more imbalanced.The slope position significantly affected the population characteristics(P<0.05).With the decreasing slope position,leaf number decreased but leaf length,width and thickness all increased,and plant height and stem length significantly increased,and roots became longer but thinner.The effect of slope position on leaf number,leaf length and leaf width,stem length,stem diameter,root length,number and width of inflorescence,floret number,and bract width of female plants all were greater than those of male plants,but leaf thickness,root diameter,and bract number of male plants were larger than those of female plants.Slope positions significantly affected biomass structure(P<0.05).The slope position had a significant effect on root,stem,leaf,and flower distribution of female plants,and root and stem distribution of male plants(P<0.05),but less influence on leaf and flower distribution of male plants.Male and female individuals of A.lactea both adapted to the habitat through morphological plasticity,and the population coefficient characteristics of sex ratio,density,age structure,and distribution indicated adaptation to the habitat.