Results of hollow presence analysis.

Pollarding and DBH affect hollow occurrence in willows. Output of generalized linear regression models with binomial distribution (coefficient estimates are on logit scale), lnDBH  =  ln-transformed DBH, factor variable management is represented by its levels, 'pollard' and 'unmanaged'. Coefficients are displayed for (A) full model with interaction between variables (lnDBH: χ2 = 172.71, d.f. = 1, P<0.001; management: χ2 = 145.34, d.f. = 1, P<0.001; lnDBH:management: χ2 = 4.21, d.f. = 1, P = 0.04) and for (B) restricted model without interaction. For both models n = 1126.