Metasequoia glyptostroboides is a well-known relict conifer species and is known as a “living fossil”. It is also endangered on the IUCN Red List. Recently, fossils of Metasequoia were found in middle Miocene deposits in Zhenyuan County of Yunnan Province, China, which is possibly the southernmost fossil record of this genus.
In a study published in Global Ecology and Conservation, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) tried to explore the possible reasons for the disappearance of Metasequoia in southwest China. They investigated the effects of temperature, water stress and storage conditions on seed germination and the effects of water stress on seedling growth of Metasequoia.
The researchers conducted controlled experiments on seed germination and seedling growth and survival over a range of temperatures and at different levels of water stress.
They found that storage time and temperature but not moisture content had a significant influence on seed germination. Water stress had a significant effect on growth of roots and stems and production of new leaves.
Low rainfall in winter and spring would cause water stress during the natural germination/seedling establishment season of Cedrus, Metasequoia and Sequoia, resulting in lack of natural regeneration of populations and eventually extinction of the species from the region.
Therefore, moisture conditions were the main factor affecting seed germination and seedling growth and survival of Metasequoia.
Their results suggest that the intensification of drought in winter and spring due to development of the monsoon climate in Asia was an important factor for the disappearance of Metasequoia in southwest China.
Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China