Grazing by wild giant pandas does not affect the regeneration of Arundinaria spanostachya

Abstract

Arundinaria spanostachya is the main bamboo species on which giant pandas forage. Information on its regeneration capacity to meet the foraging demands of pandas is important to ensure the long-term survival of pandas. In 2014, 2 plot types (grazed versus control) were selected in the winter habitat used by one wild giant panda. Various morphological and regeneration characteristics of the bamboo were assessed in the respective plots during 2014 and 2015. The panda avoided feeding on bamboo with a basal diameter of < 6 mm, preferentially feeding on intermediate-sized bamboo. The density of new shoots and the recruitment rate of shoots were significantly higher in the grazed plots compared to the control plots. The annual recruitment rate of shoots was markedly higher than the annual mortality rate in the same plot type. After grazing, the basal diameter and height of new bamboo were similar between the 2 plots. In the grazed plots, the basal diameter of new bamboo was similar to that of the stumps. Innutrition and foraging by insects were the main factors influencing the survival of new shoots. Our results showed that grazing by giant pandas helped the clonal regeneration of A. spanostachya populations, with the basal diameter of new bamboo shoots meeting the foraging demand of pandas. However, information on the carrying capacity of A. spanostachya is necessary to ensure sufficient forage matter is available for reintroduced giant pandas. Furthermore, fertilization and insect control measures should be implemented during the shooting period to optimize A. spanostachya resources.