Inhaltszusammenfassung

At three sites in northern Germany in which oak decline occurred during the last decade, the impact of soil water conditions on oak damage was investigated in one healthy and one declining stand of pedunculate or sessile oak, respectively (Quercus robur L and Q petraea [Matt] Liebl). Soil matric potentials were determined with tensiometers, and xylem water potentials as well as relative water content and osmotic pressure of the leaves were measured in oaks differing in the degree of damage. ... At three sites in northern Germany in which oak decline occurred during the last decade, the impact of soil water conditions on oak damage was investigated in one healthy and one declining stand of pedunculate or sessile oak, respectively (Quercus robur L and Q petraea [Matt] Liebl). Soil matric potentials were determined with tensiometers, and xylem water potentials as well as relative water content and osmotic pressure of the leaves were measured in oaks differing in the degree of damage. Additionally, the distribution and biomasses of fine roots were investigated. More negative soil matric potentials in the declining stand of pedunculate oak and lower relative water contents of the leaves of damaged trees even in a vegetation period with sufficient precipitation indicated a higher risk of drought stress in dry years. At the two sites with sessile oaks, the impact of drought on tree water relations seemed to be much smaller. The relative water content of leaves from damaged oaks was not lower than of those from healthy trees, even in an extremely warm and dry period. At these sites, crown reduction may be a temporary form of adaptation to insufficient water supply and, in this case, would have to be differentiated from "oak decline" in its true sense. Generally, distinct reductions in fine root biomass and an increased percentage of dead fine roots were detected only in severely damaged trees, indicating that root decay is not a primary factor in the complex of oak decline.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
Pflanzenwissenschaften

DDC Sachgruppe:
Biowissenschaften, Biologie