西藏极小种群野生植物密叶红豆杉种群的性比及雌雄空间格局

Sex ratio and spatial pattern of Taxus fuana,a Wild Plant with Extremely Small Populations in Tibet

雌雄异株植物种群具有性比和雌雄个体空间分布格局,这对个体成功繁殖、种群生存潜力、天然更新能力和遗传多样性的维持都是重要的,对于珍稀濒危雌雄异株植物种群尤其如此。密叶红豆杉(Taxus fuana)为国家I级重点保护植物,是首批列入《全国极小种群野生植物拯救保护工程规划》的120种极小种群野生植物之一,具有重要的生态和经济价值。但目前关于密叶红豆杉种群生态学方面的研究,尤其是性比结构与空间分布格局在国内外鲜有报道。本文对西藏吉隆地区的6个天然密叶红豆杉种群(吉普、多甫、朗久、吉隆、开热和唐蕃)进行了实地调查,研究其性比结构及其空间分布格局。结果表明,调查的6个种群中总计雄株1,651株,雌株1,231株,仅吉普(雄/雌=1.89)与吉隆(雄/雌=1.39)两个种群有显著的性别偏倚现象且显著偏雄性(P<0.001)。6个种群雌雄植株间的空间相关性不强,整体趋于相互独立。不同径级间,吉隆和开热种群的性比格局相似,均在小径级上性比显著偏雄性,而吉普种群则在中等径级上显著偏雄性。综上,不同密叶红豆杉种群的大小、性比、雌雄个体的大小级结构以及空间分布格局等均表现出不同。因此,需要结合各个种群本身的发展动态、受干扰的类型以及各区域环境因子的差异进行有针对性的保护。

Dioecious plant populations possess sex ratio and gender distribution of individuals,which are important for individual reproduction,population viability,natural regeneration and maintenance of genetic diversity.This is particularly true for rare and endangered dioecious ones.In China,Taxus fuana is among the 120 Wild Plant with Extremely Small Populations(WPESP)and observed only in the Jilong County of Tibet Autonomous Region.However,little has been reported about its population ecology,especially about its sex ratio and gender spatial distribution pattern of individuals.We did a field investigation for six T.fuana populations in Jilong and recorded 1,651 male and 1,231 female individuals in total,whereby its sex ratio and gender spatial distribution pattern of individuals per population were analyzed.Our results showed that Jipu(male/female=1.89)and Kaire(male/female=1.39)populations tended to be male-biased(P<0.001),but male and female individuals from the six populations showed weak spatial association.Individuals of smaller size of Jilong and Kaire populations showed significantly male-biased,while male biased occurred medium size of Jipu population.In summary,T.fuana populations were different in size structure distribution,sex ratio,size structure of male and female individuals,and their spatial patterns.Our study suggests that it is necessary to carry out targeted conservation considering different population characteristics,disturbance types,and environmental factors.