野化培训大熊猫采食和人为砍伐对拐棍竹无性系种群生物量的影响

采用固定样方法和定位观察法连续测定了2003～2007年间卧龙自然保护区大熊猫野化培训圈内及其附近区域的拐棍竹无性系种群数量和生长发育特性等参数,运用收获法与非破坏性重量估测法建立了不同龄级和残桩的竹子种群和分株生物量估测模型,进而利用最佳模型计算并评估了野化培训大熊猫采食和人为砍伐对拐棍竹无性系种群生物量和植株个体生物量的影响.结果表明:在环境条件、种群密度、生长发育特征和种群生物量等基本相似的基础上,大熊猫采食和人为砍伐不仅降低实验期间的竹子生物生产力,而且影响到后期阶段实验种群的恢复与发展.大熊猫采食样方中的竹子种群生物量虽然较对照样方低,就竹笋生物量而言,约为对照的57.79%,这与野化培训圈的面积较小、竹种单一而使采食比重(67.07%)较大有关,但其各龄级植株个体生物量均能达到大熊猫的取食利用标准(仅2004年生竹除外),具有持续供给大熊猫食物资源的潜力;而人为砍伐措施与大熊猫采食相比,影响效果极为强烈,它严重降低了拐棍竹无性系的种群生物量,尤其是竹笋重量更是如此,仅为对照样方的14.69%,且植株个体鲜重远低于大熊猫的觅食条件.因此,竹笋和无性系植株的生物量是大熊猫采食标准的主要因素.

Effects of Wildness Training Giant Pandas’ Grazing and Artificial Harvesting on Clone Population Biomass of Umbrella Bamboo(Fargesia robusta)

Giant pandas(Ailuropoda melanoleuca) have evolved to be obligate bamboo grazers,and 99% of their diets consist of subalpine bamboo species.The life span of giant pandas are directly related to the life cycle of the bamboo which pandas feed on,so the regeneration of bamboo is directly linked to survival and conservation of giant pandas.The biomass of population and ramet were used to evaluate the impact of panda foraging and artificial harvesting on the sustainability of umbrella bamboo(Fargesia robusta) in Wolong Nature Reserve,China.From 2003 to 2007,the population density,age,and growth characteristics of F.robusta clone were monitored by the methods of the immobile plot sampling and positioning observation.Three types of plots were located in the reserve: Grazed(bamboo in the wildness training enclosure from July 2003 to September 2004),harvested(bamboo cut in the spring of 2004),and control(no treatments from 2003 to 2007).The simultaneous regressive models of each age-class bamboo and remnant stake biomass in both ways of population and ramet were constructed using the methods of harvest and non-destructive volume estimation.Then the effects of wildness training pandas’ grazing and artificial harvesting on the clone population and ramet biomass of F.robustawe were analyzed according to the models.Controlling the demographic,morphologic,population biomass and environmental conditions,panda feeding and artificial harvesting resulted in a reduction of bamboo productivity,and influenced the restoration and development of experimental populations from 2005 to 2007.Compared to the bamboo population biomass in the control plots,the value in panda grazed plots was lower(e.g.bamboo shoot biomass in grazed plots was 57.79% of that in control plots).The ramet biomass of each age-class bamboo was up to the standards of panda feeding,with the exception of 2004 year,and was in capacity of sustainingly providing food resources to pandas.However,the population biomass of F.robusta clone decreased dramatically due to the artificial harvest(e.g.bamboo shoot biomass was 14.69% of that in control plots).Therefore,bamboo shoot and ramet biomass were mainly reason for the qualification for panda grazing.