Tsuga, a genus of conifers in the subfamily Abietoideae of the pine family, plays a significant role in subalpine and lowland moist coniferous forests as well as broad–leaved forests. Previous study indicates that Tsuga is a good indicator of climate change and has received wide attention. However, the most important climate variables driving the distribution of Tsuga are not yet clearly identified.
In a study published in Ecological Indicators, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and their collaborators tried to investigate the climate factors that shape the distribution of Tsuga, identify climate thresholds, and elucidate distribution dynamics in the context of significant climate changes over the past 1070 thousand years (ka).
The researchers applied the maximum entropy (MaxEnt) model by combining distribution data for Tsuga with abundant pollen fossil data to assess the present, past, and future potential distribution regions of the species in East Asia (EA), eastern North America (ENA), and western North America (WNA).
They found that precipitation was the most crucial climate variable affecting Tsuga distribution, with different regions showing sensitivity to either summer or winter precipitation. The survival of Tsuga was strongly influenced by winter and summer temperatures.
Moreover, the seasonal precipitation demand of Tsuga varied in different regions. In EA, summer precipitation and winter temperatures exhibited a strong impact on Tsuga distribution, while winter precipitation, annual precipitation, and winter temperatures played key roles in NA, ENA, and WNA, respectively.
The result indicated that the decreases in summer precipitation and winter temperatures may have led to the extinction of Tsuga in Europe. In EA, the potentially suitable area for Tsuga was larger during relatively cold periods. In NA, the potentially suitable area expanded during relatively warm periods.
The researchers proposed special attention should be given to monitoring the natural growth status of Tsuga populations. They also suggested to have customized conservation approaches, especially ex-situ conservation measures, artificial introduction and cultivation.
"It is crucial to prioritize assessing the impacts of precipitation changes on the distribution of Tsuga,” said LI Shufeng of XTBG.

Contact
LI Shufeng Ph.D
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: lisf@xtbg.org.cn
First published: 6 January 2024