汶川地震对大熊猫主食竹——拐棍竹竹笋生长发育的影响

为了了解汶川地震对大熊猫主食竹生长发育的影响,2009年10月—2011年4月,在地震重灾区四川龙溪-虹口国家级自然保护区内设置150个样方,就地震强度、中度、轻度干扰对大熊猫主食竹拐棍竹(Fargesia robusta)竹笋生长发育的影响进行了研究。研究结果显示:(1)发笋物候上,地震强度干扰的发笋时间(Julian时间)较中度和轻度干扰显著推迟,而发笋期不受影响。(2)发笋量和当年生幼竹数是拐棍竹更新生长的数量指标。地震强度和中度干扰样方的发笋量都显著高于轻度干扰,而发笋量在强度和中度干扰间差异不显著;地震强度干扰样方的当年生幼竹数显著高于中度和轻度干扰,中度和轻度干扰样方间差异不显著。这说明地震的强度和中度干扰都有利于拐棍竹竹笋和当年生幼竹数量的更新。(3)基径和株高是拐棍竹更新生长的质量指标。强度干扰下拐棍竹的基径和株高都显著小于中度和轻度干扰,中度干扰样方的基径与轻度干扰差异不显著,但株高显著矮于轻度干扰样方。表明强度干扰下拐棍竹的质量最差,中度干扰的基径已基本得到恢复,但株高仍受到抑制。(4)地震不同干扰等级拐棍竹退笋原因划分为:外力机械损伤、动物取食、生长停止、其他4种。对地震不同干扰等级拐棍竹退笋原因比率的分析发现,强度干扰样方因外力机械损伤和生长停止退笋的比率显著高于中度和轻度干扰样方,而因动物取食退笋的比率显著低于中度和轻度干扰样方。证明强度干扰样方的竹笋更容易受到外力机械损伤和生长停止退笋,而中度和轻度干扰的竹笋更倾向于动物取食致退,揭示了拐棍竹的生长是与震后不同程度的干扰相适应的。

Effects of the Wenchuan Earthquake on shoot growth and development of the umbrella bamboo (Fargesia robusta), one of the giant panda's staple bamboos

The umbrella bamboo (Fargesia robusta) is one of the staple bamboos for giant panda (Ailuropoda melanoleuca). The shoot growth and development of umbrella bamboo were investigated in the Sichuan Longxi-Hongkou National Nature Reserve from October 2009 to April 2011, and the effects of the Wenchuan Earthquake on the bamboos were evaluated as well. According to the damage degrees caused by the earthquake and its secondary geological disaster to umbrella bamboo population, the disturbances from the earthquake were classified into intense, moderate and slight types. Fifty plots were set in the population corresponded to each type, and a total of 150 plots were set in the reserve. The shooting time (Julian day) was significantly delayed in the plots with intense disturbance compared with that in the plots with moderate and slight disturbances, while the shooting time displayed no significant difference between the plots with moderate and slight disturbances. The shooting durations showed no difference among plots with three different types of earthquake's disturbance. The regeneration of umbrella bamboo was investigated based on quantity index of number of annual shoots and young bamboos. Numbers of annual shoots in the plots with intense and moderate disturbances were significantly higher than that in the plots with slight disturbance, while that between plots with intense and moderate disturbances showed no significant difference. Numbers of annual young bamboos in plots with intense disturbance was the highest, while that in the plots with moderate and slight disturbances were not significantly different. This showed that intense and moderate disturbances from the earthquake promoted the regeneration of umbrella bamboo through increasing the numbers of annual shoots and young bamboos. The regeneration of umbrella bamboo was investigated based on quality index of basal diameter and culm height as well. Basal diameter and culm height in the plots with intense disturbance were obviously smaller than that in the plots with moderate and slight disturbances. Basal diameter in the plots with moderate disturbance had no significant difference to that in the plots with slight disturbance, whereas culm height was significantly lower than that in the plots with slight disturbance. It indicated that quality of the umbrella bamboos in the plots with intense disturbance was the worst, and basal diameter in the plots with moderate disturbance had been basically restored, but culm height was still limited. The withered shoots in the plots with different levels of disturbances were attributed to external mechanical damage, animal feeding, growth stop and etc. In the present study, the rates of withered shoots due to external mechanical damage and growth stop in the plots with intense disturbance were significantly higher than that in the plots with moderate and slight disturbances. Moreover, the rates of withered shoots due to animal feeding in the plots with intense disturbance were significantly lower than that in other disturbance plots. It suggested that bamboo shoots in the plots with intense disturbance were much vulnerable to external mechanical damage and growth stop, however, that in the plots with moderate and slight disturbances were easy to die due to animal feeding. Shoot growth of umbrella bamboo after earthquake was adapted to the different degrees of disturbances in the natural reserve.