花旗松的年輪 growth of Douglas fir tree

 花旗松的年輪

(A)花旗松(Pseudotsuga menziesii)誕生。 (B) 生長迅速，形成較寬、均勻的年輪。 (C) “反應木”有樹枝壓到樹木而產生。 (D)生長被其它樹檔住太陽。 (E) 競爭樹木被移除，再次快速生長。 (F) 火燒傷了樹。 (G)長時間的干旱造成狹窄的年輪。 (H)可能是由昆蟲引起的狹窄的年輪。

growth of Douglas fir tree

Annual growth rings of a tree trunk

(A) A Douglas fir (Pseudotsuga menziesii) is born. (B) Growth is rapid, forming relatively broad, even rings. (C) “Reaction wood” is formed to help support the tree after something fell against it. (D) Growth is straight but crowded by other trees. (E) Competing trees are removed, and growth is again rapid. (F) Fire scars the tree. (G) Narrow rings are caused, probably by a prolonged dry spell. (H) Narrow rings may have been caused by an insect.

資料來源:

https://www.britannica.com/science/growth-ring-plant-anatomy