拐棍竹对汶川地震滑坡干扰的响应

Response of the umbrella bamboo(Fargseia robusta) towards disturbance of landslide in the Wenchuan Earthquake

拐棍竹(Fargseia robusta)是大熊猫的主食竹之一,2008年汶川地震及其次生灾害损毁了大量拐棍竹.为了解汶川地震后拐棍竹种群的恢复动态,评估拐棍竹种群的恢复能力,揭示拐棍竹种群对不同程度滑坡体干扰的响应策略,于2010年4月-2013年4月,在地震重灾区都江堰市四川龙溪–虹口国家级自然保护区,对受到地震滑坡体不同程度干扰(强度、中度、对照)的3种样地150个样方中拐棍竹的更新情况进行了监测和分析.结果显示:(1)不同程度干扰样方的发笋量、存活量、单位面积生物量均存在年间波动;(2)发笋量和存活量有显著正相关关系,强度干扰样方的年成活率最高,总体趋势是受干扰样方的发笋和存活数量显著高于对照;(3)强度干扰样方的更新竹基径、株高呈现出逐年增加的趋势,而中度表现出了波动的形式;(4)到2012年,无论发笋量、存活量、生物量还是种群有限增长速率,中度干扰样方都显著高于对照.本研究表明,地震滑坡干扰后,拐棍竹种群经过4年的更新生长后在数量和质量上都得到了较好的恢复,中度干扰样方的恢复好于强度;种群的恢复策略为能量分配优先供应于数量生长,然后再到营养生长.

Umbrella bamboo （Fargseia robusta）, a staple bamboo for giant panda, was severely destroyed by secondary disasters （landslide, collapse, debris？flow, etc.） following the Wenchuan Earthquake. This study aimed to investigate the shooting trends of the umbrella bamboo in three different levels of landslide disturbance （strong, moderate and control）, to understand the regeneration dynamics of umbrella bamboo population, to determine the relationship between the biomass and shoot number and survival amount, and finally to make an assessment of the resilience of the umbrella bamboo after seismic landslide disturbance. Our study was conducted in the Longxi-Hongkou National Nature Reserve, Dujiangyan, Chengdu, China. A total of 150 permanent quadrats （2 m × 2 m） were set at 3 sites in different levels of landslide disturbance （strong, moderate, control） with 50 quadrats each. The newly generated bamboo shoots and degraded shoots were counted and labeled; the basal diameter （cm） and height （mm） of the annual shoot were measured by tape from the first new bamboo shoot in April until no new shoot. All the counts and measurements were repeated in October. Our results showed that： （1） the number of newly generated and surviving bamboo shoots as well as the biomass per unit area fluctuated in all disturbance levels from 2010 to 2012. （2） The shoot number showed a significantly positive correlation with survival amount; the shoot number and survival amount in disturbed sites were significantly higher than that in the control site; the survival rate of the bamboo shoot was the highest in the strong disturbance site. （3） The height and basal diameter of the regenerated bamboo tended to increase year by year in the strong disturbance site, but fluctuated in the moderate disturbance site. （4） The shoot number, survival amount, biomass per unit area and the clone rate in the moderate disturbance site were significantly higher than those in the control by 2012. Our results suggested that four years after seismic landslide disturbance, the umbrella bamboo has recovered to some degree, with the clone population recovery better in moderately disturbed places than the strongly disturbed ones. The recovery strategy of F. robusta is giving priority to energy supply for increase of bamboo numbers, then for vegetative growth.