TAILIEUCHUNG - Báo cáo lâm nghiệp: "Xylem acoustic signals from mature Pinus sylvestris during an extended drought"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Xylem acoustic signals from mature Pinus sylvestris during an extended drought. | Ann. For. Sci. 61 2004 1-8 INRA EDP Sciences 2004 DOI forest 2003079 1 Original article Xylem acoustic signals from mature Pinus sylvestris during an extended drought Michael P. PERKSa b James IRVINEa John GRACEa a Institute of Ecology and Resource Management University of Edinburgh Darwin Building Mayfield Road Edinburgh EH9 3JU UK b Current address Forest Research Northern Research Station Bush Estate Roslin Midlothian Scotland EH25 9SY UK Received 18 july 2002 accepted 17 December 2002 Abstract - Mature Scots pine Pinus sylvestris L. were subjected to an 11 month imposed soil drought from November 1994. Control plots received rainfall plus irrigation. The extent of cavitation in the xylem of branches and boles was compared using ultrasonic acoustic emission UAE measurements. Supporting measurements of the relative water content Rw of the bole and shoot were recorded. Acoustic emissions were detected in both treatments. An effect of water-stress in both boles and branches at the height of the drought was noted. Differences in vulnerability were found and suggest a reduced vulnerability to cavitation of remaining functional conduits after loss of the most vulnerable conduits in the water-stressed trees. Bole Rw was lower than branch Rw. In 1-year-old shoots of draughted trees a significant increase in xylem embolism was found. Seasonal changes in shoot Rw were interpreted as the occurrence and recovery refilling of emboli in xylem tissues an active role of precipitation is hypothesised. It was estimated that 15 of tracheids were cavitated without affecting above-ground hydraulic resistances. It is suggested that runaway cavitation was avoided through stomatal closure maintaining leaf water potential indicative of xylem tension below the cavitation threshold and thereby little effect of drought was evident in above ground tissues. drought Pinus sylvestris Scots pine time domain reflectometry ultrasonic acoustic emissions xylem cavitation Résumé - Signaux .

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