Cold tolerance of conifers : a research proposal to the Maine Agricultural Experiment Station

Livingston, William

'Variation in climate temperatures will affect the cold tolerance of conifers. A reasonable hypothesis is that warm temperatures will reduce the cold tolerance of conifers and predispose the trees to winter injury. In natural populations, warm periods followed by subfreezing temperatures could damage trees resulting in growth declines. In tree nurseries, trees are subjected to warmer, artificial climates which reduce the cold tolerance of shoots and roots. Also, use of exotic tree species from warmer climates in tree improvement programs may have inadequate cold tolerance for the climate of the plantations. Because cold tolerance is a critical factor in the survival and growth of natural and cultivated conifers in Maine, the objectives of this project are to: (1) ascertain how seasonal cold tolerance of red spruce (Picea rubens) and white spruce (P. glauca) is influenced by the more moderate and acidic climate along Maine's coast versus the inland climate; (2) examine the development of shoot and root cold tolerance of conifers in tree nurseries, and elucidate how root cold tolerance can be managed within the nursery; and (3) determine the variation in spring cold tolerance between and within larch species that are used in tree improvement programs, and examine relevance to subsequent long term growth in plantations. Similar equipment and methodology will be used in the proposed studies that relate to the project's objectives. Shoot and root tissue will be exposed to sub-freezing test temperatures in a programmable chamber. Subsequent shoot damage will be quantified by using increases in electrical conductivity of a bathing solution. Root damage will be quantified by placing tissue in a pressure chamber and measuring the percent weight loss. This project will be able to provide data for developing and improving hypotheses on how temperature changes could affect the cold tolerance of conifers in Maine's natural and cultivated forests.' /STUDY LOCATIONS:/ /ISLE AU HAUT/