Pan Libing, Song Xiaoyang, Zhang Wenfu, Yang Jie, Cao Min
CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla 666303, Yunnan, China.
College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Divers. 2024 May 2;46(5):671-677. doi: 10.1016/j.pld.2024.04.010. eCollection 2024 Sep.
We used 11 years of census data from 450 seedling quadrats established in a 20-ha forest dynamics plot to study seedling dynamics in tree species of a tropical seasonal rainforest in Xishuangbanna, southwestern China. We found that overall seedling recruitment rate and relative growth rate were higher in the rainy season than in the dry season. Both the recruitment rate of seedlings from canopy tree species (two species) and the relative growth rate of seedlings from understory species (nine species) were higher in the rainy season than in the dry season. However, in the rainy season, the recruitment rate of seedlings was higher for canopy tree species than for understory tree species. In addition, relative growth rate of seedlings was higher in the canopy species than in understory seedlings in the dry season. We also observed that, in both rainy and dry seasons, mortality rate of seedlings was higher for canopy species than for understory species. Overall, canopy tree species appear to have evolved a flexible strategy to adapt to the seasonal changes of a monsoon climate. In contrast, understory tree species seem to have adopted a conservative strategy. Specifically, these species mainly release seedlings in the rainy season and maintain relatively stable populations with a lower mortality rate and recruitment rate in both dry and rainy seasons. Our study suggests that canopy and understory seedling populations growing in forest understory may respond to future climate change scenarios with distinct regeneration strategies.
我们利用在中国西南部西双版纳一片20公顷的森林动态监测样地中设立的450个幼苗样方的11年普查数据，研究热带季节性雨林树木物种的幼苗动态。我们发现，总体幼苗补充率和相对生长率在雨季高于旱季。冠层树种（两种）的幼苗补充率和林下物种（九种）的幼苗相对生长率在雨季均高于旱季。然而，在雨季，冠层树种的幼苗补充率高于林下树种。此外，旱季时冠层物种的幼苗相对生长率高于林下幼苗。我们还观察到，在雨季和旱季，冠层物种的幼苗死亡率均高于林下物种。总体而言，冠层树种似乎已经进化出一种灵活的策略来适应季风气候的季节变化。相比之下，林下树种似乎采取了保守策略。具体而言，这些物种主要在雨季释放幼苗，并在旱季和雨季保持相对稳定的种群数量，死亡率和补充率较低。我们的研究表明，生长在森林林下的冠层和林下幼苗种群可能会以不同的更新策略应对未来气候变化情景。
