Growth and interspecific interactions of the rare oak polypore Piptoporus quercinus.

Growth and interactions of Piptoporus quercinus were studied in artificial culture to give insights into the ecological characteristics of a species which is both rare and widespread. P. quercinus grew slowly under all conditions, the maximum ranging between 1.9 and 3.15 mm d(-1), depending on isolate, at 25 degrees C pH 3.75. Upper limits for growth were 25-30 degrees or above 30 degrees depending on isolate, and pH 6.6. Lower limits for growth were 5-10 degrees, between -1.75 and -2.5 MPa; there was still growth at pH 1.81. Preincubating plates at 5 for 77 d and then incubating at 20 degrees resulted in a significantly greater extension rate (2.89 mm d(-1)) than when incubated continuously at 20 degrees (1.70 mm d(-1)) for one isolate though not for another isolate. P. quercinus survived exposure to low temperature (-18 degrees for 7 d), showing renewed growth, albeit limited, after a lag of 37 d. It was a poor combatant, being unable to replace any of the eight fungi (with a range of ecological roles) against which it was paired, and being replaced or partially replaced by most, on 2% MA at pH 5.49, at pH 3.75 and at -1.25 MPa. It did, however, inhibit extension rate of some other heart rot fungi. Results are discussed in an ecological context.