青杨雌雄群体沿海拔梯度的分布特征  

The distribution of male and female Populus cathayana populations along an altitudinal gradient

作　　者：王志峰[1,2] 胥晓[1,2] 李霄峰[1,2] 杨鹏[1,2] 袁新利 

机构地区：[1]西华师范大学生命科学学院,南充637002 [2]西南野生动植物资源保护教育部重点实验室,南充637009 [3]小五台山国家自然保护区,蔚县075700

出　　处：《生态学报》2011年第23期7067-7074,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(30771721)

摘　　要：以小五台山天然青杨种群为试验对象,通过在其分布海拔范围内(1400—1700 m)设置样方的方式研究青杨雌雄群体的平均胸径、密度、性比、大小级结构和空间分布的差异。结果显示:雌株群体的平均胸径在整个海拔梯度上无显著差异,而海拔1700 m处的群体密度显著低于其它海拔;雄株群体的平均胸径在海拔1700 m最大,显著高于其它海拔,而群体密度在各海拔梯度间无显著差异。在海拔1600 m,雌雄群体的平均胸径最接近,同时密度也最接近。从整个海拔范围来看,青杨雌雄个体的比例(雄/雌)为0.80∶1,性比不偏离1∶1(χ2=2.94,P>0.05)。但在不同海拔梯度上性比有所不同,低海拔性比为0.44,显著偏雌(χ21400=5.91,P<0.05),而高海拔性比为2.55,显著偏雄(χ21700=6.56,P<0.05);随着海拔接近1600 m,性比逐渐趋于1∶1(χ21600=0,P>0.05)。除海拔1700 m为下降型外,青杨雌雄群体的大小级结构在其它海拔主要表现为稳定型。而最稳定群体结构的分布海拔在雌雄群体间不同。在海拔1400 m,雌株群体中Ⅰ级和Ⅱ级植株占群体比例最大;雄株群体Ⅰ级和Ⅱ级植株占群体比例最大的海拔是1600 m。群体空间分布以聚集分布为主,彼此间无明显差异;但群体间聚集强度的变化在海拔梯度上各有不同,主要表现为雌株群体的PAI随海拔的升高逐渐增加,而雄株群体的PAI则随海拔的升高呈现出先增加后减少的趋势。研究结果表明了青杨雌雄群体的分布特征沿海拔梯度的变化明显不同,中等海拔区域可能为青杨种群的最适繁衍区。Dioecious plant species are an important component of terrestrial ecosystems. However, little is known about their ecology, including the factors affecting their distribution. We investigated the ecology of Populus cathayana Rehd, a dioecious and deciduous species that occupies a wide range of habitats in China. We measured the mean diameter at breast height （DBH）, population density, sex ratio, size structure, and spatial distribution of male and female P. cathayana populations in a series of forest plots along an altitudinal gradient （ 1400--1700 m） in the Xiaowutai Mountains. The results showed that the trends in mean DBH and density were significantly different for males and females. There was no significant difference in mean DBH along the altitudinal gradient in female populations and the population density at 1700 m was lower than at other altitudes. Compared with females, the maximum mean DBH for males was observed at 1700 m and was significantly larger than at other altitudes. However, there was no variation in the population density of males associated with altitude. The mean DBH in male and female populations was nearly equal at 1600 m and the density at this altitude was also very similar among male and female populations. The sex ratio （ male ： female ） tended to increase along the altitudinal gradient. Although the sex ratio was close to 1：1 （χ2 = 2.94, P 〉 0.05 ） for the entire population （ 1400--1700 m）, the ratio was biased towards females （χ2 1400 = 5.91, P 〈 0.05） at low altitudes and biased toward males （χ2 1700 = 6.56, P 〈 0.05 ） at high altitudes. The sex ratio approached 1 ： 1 （χ2 1600 = 0, P 〉 0.05 ） as the altitude tended towards 1600 m. Furthermore, the size structure of all male and female P. cathayana populations revealed a steady-state distribution along the altitudinal gradient （except for a decline-state distribution at 1700 m）. However, the distribution of the size classes differed between male and female P. eathayana populatio

关 键 词：雌雄异株 海拔梯度 种群密度 性比 分布格局 青杨 

分 类 号：Q948[生物学—植物学]