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The Relationship Between Basal Fire Scars and Crown Damage in Giant Sequoia
Author(s) -
Rundel Philip W.
Publication year - 1973
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934393
Subject(s) - sequoia , snag , crown (dentistry) , tracheid , xylem , biology , basal area , botany , ecology , materials science , composite material , habitat
A strong correlation exists between the presence of basal fire scar in giant sequoia and the occurrence of snag—tops in mature trees. The percentage of snag—top trees is directly related to the size of the basal fire scar. Approximately 50% of trees with the fire scars greater 100 ft 2 possess a snag—top. Evidence indicates that the physiological basis for the formation of snag—tops is a response to high water stresses in the uppermost crown of a mature tree. Fire damage at the base of the tree destroys large amounts of active xylem tissue, thereby reducing the rate of water absorption. When water stress exceeds the physiological tolerance limits for giant sequoia, the top of the main trunk is the first area damaged. The critical level of water potential at the top of a mature giant sequoia has not been determined, but evidence indicates that trees may survive xylem pressure potentials somewhat lower than —20 bars for short periods of time at midday without damage. Water potentials lower than this may provide a significant limiting factor in determining the upper height limits of these trees.