Effects of warming on the seedling adaptation and growth of Machilus gamblei in a subtropical forest

Abstract

Accurate predictions of community stability feedback to climate warming depend on an advanced understanding of responses of the key species. The transition from seed germination to seedling establishment is the most vulnerable stage of plants, which determines the maintenance of plant diversity and community resistance to climate change. To elucidate how the establishment and physiological characteristics of Machilus gamblei seedlings will respond to future global warming, artificial warming experiments (infrared warming, +0.75 ℃, +1.5 ℃, +3 ℃, +4 ℃) were conducted at the Ailao Mountain National Nature Reserve in Yunnan Province, China. The responses of seedling establishment and their physiological adaptation to different warming conditions were studied, and the contents of nutrients, chlorophyll, and nonstructural carbohydrate (NSC) in the leaves were measured. The results showed that: (1) increasing the temperature by 0.75 ℃ did not affect the survival rate or physiological characteristics of the seedlings, but increasing the temperature by 4 ℃ reduced the survival rate of the seedlings; (2) As the temperature increased from 1.5 ℃ to 3 ℃, the chlorophyll production in the seedling leaves improved, thus particularly promoting the accumulation of NSC by increasing the starch content. In summary, our work suggests that the temperature increase in 1.5 ℃ and 3 ℃ might be conducive to the establishment and growth of Machilus gamblei seedlings in the two-year experimental period, but increasing the temperature by 4 ℃ would threaten their survival and development.