Mechanisms of Xylem Embolism in Tree Species
{'Code': '08010207', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'DEB', 'LongName': 'Division Of Environmental Biology'}}
{'SignBlockName': 'Joann P. Roskoski', 'PO_EMAI': None, 'PO_PHON': None}
Embolism in the xylem of plants is the presence of air-                    filled xylem conduits (tracheids and/or vessels) and it can lead                to a significant reduction in water transport capacity.  This in                turn can adversely influence the water balance of the plant                     causing reduction of growth and dieback.  In a preliminary study                of embolism in sugar maple (Acersaccharum) trees in northern                    Vermont, Sperry and Tyree found that during the winter the xylem                of saplings became over 70% embolized, with many small twigs                    losing all of their water conducting capacity to embolism.                      Gradual recovery from winter embolism occurred during the spring                and was associated with the development of positive xylem                       pressures.  In their proposed research, Sperry and Tyree will                   determine how widespread the phenomenon of winter embolism and                  recovery is in co-occurring tree species representing ring-and                  diffuse-porous angiosperms, and conifers.  This will be done in                 the context of year-round monitoring of embolism levels for each                species over the period of funding.  Through field and laboratory               manipulations they intend to determine the causal link between                  environmental conditions and the induction of embolism, as well                 its reversal.  This information will guide them in assessing how                important xylem embolism is in the ecological tolerance of tree                 species, and in explaining episodes of species dieback and                      decline.  This research may have important consequences for                     silvicultural practices, including the establishment of                         plantations and management of existing stands, especially in                    regions where winter injury is prevalent.  By determining the                   mechanism of embolism induction, this research will also evaluate               how important embolism is in the influence of environmental                     stress on tree health.
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{'Name': 'University of Vermont & State Agricultural College', 'CityName': 'BURLINGTON', 'ZipCode': '054051704', 'PhoneNumber': '8026563660', 'StreetAddress': '85 S PROSPECT STREET', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Vermont', 'StateCode': 'VT', 'CONGRESSDISTRICT': '00', 'CONGRESS_DISTRICT_ORG': 'VT00', 'ORG_UEI_NUM': 'Z94KLERAG5V9', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF VERMONT & STATE AGRICULTURAL COLLEGE', 'ORG_PRNT_UEI_NUM': None}
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