The genetic variation of a species with a seemingly wide plasticity. Inhabits from wet forest understory to arid steppe environments. et Bizzarri (Cupressaceae) has highĮcological and economic importance in northern Argentine Patagonia. The PatagonianĬypress Austrocedrus chilensis (D. In the context of climateĬhange, we need to know the genetic variation of key adaptive traits. And second, the ‘Pleistocene ratchet’-the propensity of many forest species that lose range during a glacial (or interglacial) to fail to recover it entirely during the subsequent interglacial (glacial).įorests are the most diverse and threatened ecosystems. First, ‘glacial–interglacial asymmetry’-trees adapted to harsh glacial climates have more difficulty persisting in the face of strong biotic competition in warm, wet interglacial landscapes than trees adapted to interglacials do in persisting in climatically protected sites in cold, dry glacial landscapes. We suggest two drivers have strongly modified both geographic and trait distribution in the flora. The pronounced oscillations in extent of dry, cool habitats and warm, moist habitats in this isolated archipelago during the Pleistocene had a profound effect on the composition and distribution of the OTF. Lack of fast-growing, ectomycorrhizal cold-tolerant trees is a key reason for the marked physiognomic differences between northern temperate broadleaved forests and those of the New Zealand OTF. Reduction in ectomycorrhizal tall tree genera left only Nothofagaceae and myrtaceous Kunzea and thus OTF formations are largely arbuscular mycorrhizal. Many low-nutrient specialists and arid-adapted Australian-origin taxa were lost, along with many now exclusively tropical genera. During the Pliocene/Pleistocene increasingly cool climates, less fire and loss of old, leached soils, reduced floristic diversity. Warm, fire-prone environments in the middle Miocene permitted an influx of Australian taxa. The OTF arose out of the warm temperate to subtropical forests of Zealandia that formed during the Palaeogene. Often described as Gondwanan or relic, tree genera characteristic of the OTF are more likely to be shared with tropical regions to the north than with temperate fragments of Gondwana (southern Australia, southern South America). Here it is designated oceanic temperate forest (OTF), its climatic envelope is defined, global distribution is assessed and origin is reviewed. The pre-clearance New Zealand lowlands were largely in complex, liana-rich, multi-layered conifer–angiosperm forest. Comprehensive lists of species’ frost resistance are included in tables and appendices. Furthermore, it also shows similarities between the frost resistance of plants from the Southern Hemisphere during the growing season and the maximum frost resistance of tropical alpine species and further similarities between species on oceanic islands in both hemispheres. It gives examples of differences in frost resistance between the two hemispheres and attributes these to the contrast between the climates of largely continental land masses in the Northern Hemisphere and the oceanic environment of the Southern Hemisphere. This review, however, is not principally concerned with physiological aspects of frost resistance, but more with biogeographic aspects of the environment and quantification of the relationships between frost resistance and temperature related factors such as altitude and latitude. It considers various methods of determining frost resistance and the expression of critical temperatures causing damage, and discusses the problems of using excised plant parts and freezing of tissues. It gives a brief overview of methods for determining frost resistance in the field and in controlled environments with intact or excised plant parts. This review contrasts the frost resistance of plants from the Southern Hemisphere with that of the Northern Hemisphere and is principally concerned with plants from New Zealand, Australia, and South America.
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