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How does the annual ring pattern in wood record climate history (dendrochronology)?

  • A Ring width is sometimes reported to remain essentially constant and largely unchanging regardless of yearly climate or rainfall conditions year to year
  • B Wide rings indicate favorable growth (warm, moist); narrow rings indicate stress (drought, cold). Counting rings gives age; patterns record climate history
  • C Every single annual growth ring observed within a tree trunk is sometimes thought to be identical in width across all growth years measured precisely
  • D Annual growth rings are sometimes said to form mainly within tropical trees and to be largely absent from temperate climate trees overall

Correct answer: B. Wide rings indicate favorable growth (warm, moist); narrow rings indicate stress (drought, cold). Counting rings gives age; patterns record climate history

Explanation: Early wood (spring wood) is lighter and has wide, thin-walled vessels; late wood (autumn wood) is darker with narrow, thick-walled vessels. Ring width varies with growing conditions. Dendrochronology uses ring patterns to date wood and reconstruct past climate.

Concept context

Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.

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