The failure of frog populations to expand into human-created habitat: Frogs do not breed in rubber plantations in Xishuangbanna, China
During the past thirty-five years, terraced rubber tree plantations have replaced over two-thirds of the native tropical rainforest in Xishuangbanna Prefecture, southwest China. Given that Xishuangbanna is part of the Indo-Burma biodiversity hotspot, and a frog diversity hotspot within China, this massive land conversion is a major concern for biodiversity. We conducted a series of surveys, experiments, and breeding-pool manipulations to determine how frogs are using rubber plantations. Surveys revealed that while adult frogs live in rubber plantations, they are not using them for breeding. Contrary to expectation, our experiments showed that rubber plantation pools are suitable for breeding: tadpoles grew and developed well in them. However, experiments using standardized breeding pools indicated that frogs bred readily in every habitat tested except rubber plantations. These results imply that behavioral limitations prevent adult frogs from breeding in rubber plantations. The failure of frogs to exploit this habitat is especially troubling because Xishuangbanna is dominated by disturbance-tolerant frog species that routinely breed in other disturbed areas. As Xishuangbanna continues to develop, more and more suitable breeding habitat will be lost while rubber plantations remain. The future of frog diversity, and possibly biodiversity in general, in Xishuangbanna will likely be severely threatened if they are unable to adapt to this new habitat.