Seasonal frost hardiness ofNothofagus solandriseedlings from two altitudinally diverse sites in Canterbury, New Zealand

Abstract

Seasonal variation in frost hardiness was evaluated in beech (Nothofagus solandrO seedlings from sites in North Canterbury at 460 m near the lower altitude limit, and at 1100 m near timberline. Both 1-and 2-year old seedlings were lifted on five occasions through the year and exposed to a range of controlled frosts. Visual frost damage was measured four weeks later as the percentage of foliage damaged, and frost hardiness determined as that temperature causing an average of 50% foliage damage.Low-altitude seedlings achieved a maximum midwinter frost hardiness of--4.5~ and about-1 ~ in summer whereas the high-altitude seedlings were respectively hardy to -11.5 and -3.5~ From a conditioning experiment, and in keeping with the differences in seasonal variation in frost hardiness, high-altitude seedlings apparently have an inherently greater capacity to develop frost hardiness than lowaltitude seedlings.

Seasonal frost tolerance ofHebespecies and cultivars

“…Variations in mid summer frost tolerance between populations of New Zealand native plants from different latitudes have also been found to be small but, in mid winter, populations in more southern latitudes have been shown to have greater frost tolerance than those from more northern locations (e.g., with Nothofagus solandri (Greer et al 1989) and Leptospermum scoparium Harris & Decourtye 1991)). Latitude of origin also influenced winter frost tolerance among provenances of Eucalyptus regnans (Rook et al 1980).…”

“…(Bannister & Lee 1989), Leptospermum scoparium Harris & Decourtye 1991), and Podocarpus totara (Hawkins et al 1991). For example, differences in maximum summer frost hardiness temperatures of Nothofagus were small between populations from different altitudes, but in mid winter hardiness temperatures were -11.5°C for high altitude populations and only -4.5°C for low altitude populations (Greer et al 1989). Similar differences resulting from altitude of origin have been determined for Acacia species (Pollock et al 1986), Eucalyptus regnans (Rook et al 1980), and Abies sachalinensis (Eiga & Sakai 1984).…”

“…Altitudinal variation in frost tolerance of New Zealand native plants has been determined in a range of species including Nothofagus solandri (Sakai & Wardle 1978;Greer et al 1989), Phyllocladus alpinus and Weinmannia racemosa (Sakai & Wardle 1978), Blechnum penna-marina (Bannister & Fagan 1989), Coprosma spp. (Bannister & Lee 1989), Leptospermum scoparium Harris & Decourtye 1991), and Podocarpus totara (Hawkins et al 1991).…”

“…At each evaluation, and particularly in winter (July), there were substantial differences in both the hardiness temperature and the lethal temperature among the different species and cultivars included in the study. The amount of frost tolerated in summer, when assessed using the hardiness temperature (Table 2), (Warrington & Stanley 1987;Greer et al 1989Greer et al , 1991 which have evolved to grow in climates where frosts, although more prevalent in winter, can occur throughout the year.…”

“…The winter frost tolerance of New Zealand trees and shrubs has been shown to correlate well with natural distribution, especially with altitude and latitude of origin (Sakai & Wardle 1978;Sakai et al 1981;Wardle 1985;Greer et al 1989Greer et al , 1991. The objective of this study was to define the seasonal frost tolerance of a wide range of Hebe species, cultivars, and hybrids selected to cover diverse growth habits, geographic distribution, and ornamental value.…”