Are frost hardiness ratings useful predictors of frost damage in the field? A test using damage records from the severe frost in South Otago and Southland, New Zealand, July 1996

Abstract

Severe and persistent frosts during the first two weeks of July, 1996, caused extensive damage to vegetation in Southland and South Otago. Air frosts as low as ‐15°C were recorded. Records of degree of damage of taxa at specific sites were sought from interested persons and collated. Observed damage was related to frost hardiness scores derived from USDA climatic zones and to experimentally determined measures of frost resistance. Sites were ranked with regard to the degree of damage of taxa in common. Severity of damage within sites was related to estimated site temperatures and distance from the sea. Frost resistance and zonal hardiness measures were better predictors of damage than escape from damage, but frost resistance measures gave the best overall prediction of damage and escape from damage in the field. A comprehensive appendix lists zonal hardiness and frost resistance of taxa in relation to observed damage in the field.

Keywords:

• frost resistance
• frost hardiness
• frost damage
• climate zone
• New Zealand