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Researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences investigated the influence of climatic factors on the anatomical traits of wood in coniferous tree species in the Hengduan Mountains. They emphasized the susceptibility of subalpine conifers to changing climate patterns and pointed to the necessity for species-specific conservation strategies.

Researchers conducted the study within the subalpine forests of the biologically diverse and climate-sensitive Hengduan Mountains. They examined two crucial features of wood cells, cell wall thickness (CWT) and lumen area (LA), in four dominant species: Abies georgei, Larix potaninii var. macrocarpa, Picea brachytyla, and Pinus densata. The results are in the journal Dendrochronologia.

Using quantitative wood anatomy (QWA) methods which provide insights into mechanisms that underpin the responses of tree physiological processes to climate change, researchers constructed chronologies of cell wall thickness and lumen area at both annual and sub-seasonal (intra-annual) scales. They found that temperature and moisture conditions during the initial to peak growing season played a pivotal role in wood cell development.

Cell wall thickness was mainly limited by low temperatures. Thicker cell walls which provide mechanical support were linked to warmer temperatures. Lumen area, a proxy of hydraulic efficiency for water transport, was largely constrained by moisture availability with larger lumens associated with wetter conditions. The daily maximum temperature had a stronger influence on cell wall thickness and lumen area than precipitation.

Moreover, researchers identified a multi-decadal scale shift which indicated a marked rise in sensitivity to moisture fluctuations in recent decades. This finding implied an escalating influence of drought stress on hydraulic function as global temperatures increase.

Furthermore, researchers found that anatomical traits displayed varying responses to climatic drivers. Abies georgei and Pinus densata demonstrated pronounced climatic sensitivity in their anatomical features. In contrast, Larix potaninii var. macrocarpa and Picea brachytyla demonstrated weaker responses, suggesting distinct adaptive strategies to their respective environments.

"The findings of this study emphasize the vulnerability of subalpine conifers to climatic fluctuations. It is imperative to develop species-specific conservation strategies," said Fan Zexin from XTBG.