樹木の形成に与える気候因子の影響(How Do Climatic Factors Impact Wood Formation at Cellular Level in Hengduan Mountains?)

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2025-09-04 中国科学院(CAS)

中国科学院西双版納熱帯植物園の研究チームは、横断山脈の亜高山針葉樹林において、気候が細胞レベルの木部形成に及ぼす影響を解析した。対象はAbies georgei、Larix potaninii var. macrocarpa、Picea brachytyla、Pinus densataの4種。定量的木材解剖により細胞壁厚(CWT)と管腔面積(LA)の年代を作成した結果、CWTは低温で制約され温暖条件で厚くなり、LAは水分条件に依存し湿潤期に拡大することが分かった。日最高気温は降水量より両指標に強い影響を示した。また近年、水分変動への感受性が増し、乾燥ストレスが水輸送機能を脅かす兆候も確認された。さらに樹種間で応答が異なり、AbiesとPinusは高い感受性を示す一方、LarixとPiceaは弱く異なる適応戦略を持つ可能性が示された。研究者は、気候変動下での亜高山針葉樹の脆弱性を強調し、種特異的な保全戦略の必要性を指摘している。

<関連情報>

中国南西部・横断山脈中部の4針葉樹種における年次および年内の木部組織形質への気候的影響 Climatic influences on annual and intra-annual xylem anatomical traits of four coniferous tree species in the central Hengduan Mountains, Southwest China

Ju-Mei Zhang, Zaw Zaw, Pei-Li Fu, Shankar Panthi, Jambay Dema, Tong-Liang Xu, Hui Zhang, Achim Bräuning, Ze-Xin Fan
Dendrochronologia  Available online: 26 August 2025
DOI:https://doi.org/10.1016/j.dendro.2025.126401

Abstract

Quantitative wood anatomy (QWA) provides valuable insights into the mechanisms underlying the responses of tree physiological processes to climate. Yet, the influence of climatic factors on the wood anatomical traits of coniferous tree species in the Hengduan Mountains remains poorly understood. This study investigated xylem anatomical traits (cell wall thickness, CWT; lumen area, LA) in four dominant coniferous species (Abies georgei, Larix potaninii var. macrocarpa, Picea brachytyla, and Pinus densata) from the subalpine forests of the central Hengduan Mountains. Using standard QWA protocols, we established chronologies for CWT and LA at both annual and intra-annual scales. Correlation analyses revealed that these xylem anatomical traits are significantly influenced by temperature and moisture conditions during early-to-peak growing season. Specifically, CWT is primarily constrained by low temperatures, while LA is limited by water availability. Responses of anatomical traits to climate factors exhibit multi-decadal scale instability, with LA showing increasing sensitivity to moisture variations in recent decades, likely associated with intensified drought stress under a warming climate. Furthermore, xylem anatomical responses to climate factors varied among the four species. CWT showed the strongest climatic sensitivity in A. georgei, LA responses were most prominent in A. georgei and P. densata, while both traits responded weakly in L. potaninii and P. brachytyla, reflecting their divergent adaptive strategies to habitat heterogeneity.

生物環境工学
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