Freezing cycles enhance winter injury in Picea rubens

Abstract

We examined changes in chlorophyll absorbency in red spruce (Picea rubens Sarg.) foliage in response to simulated freezing cycles. Current-year branch tips were collected from 16 trees on January 8, January 20, February 8 and February 26, 1996. Tissue was subjected to freezing cycle treatments with a minimum of -35 degrees C and a maximum of 3 degrees C for a one-cycle treatment, and -9, -6, -3, 0 or 3 degrees C for four-cycle treatments. Samples were frozen at a rate of 5 degrees C h(-1), and warmed at 12 to 15 degrees C h(-1). Controls were held at -9 degrees C. Temperatures during the three-day periods preceding each sample date averaged -18, 4.7, -9.6 and 3.7 degrees C, respectively. On January 8, treated trees showed no significant (P > 0.1) increase in the breakdown of chlorophyll, as measured by the ratio of chlorophyll a absorbency (435 nm) to phaeophytin a absorbency (415 nm), compared with control branch tips. On later sampling dates, seven trees consistently exhibited needle reddening and nine exhibited few symptoms (< 10% of total needle surface reddened) after four-cycle treatments. On February 26, chlorophyll degradation in trees with needle reddening differed (P < 0.05) from the control by 26, 26, 16, 14 and 15% for the 3, 0, -3, -6 and -9 degrees C maxima, respectively. No detectable chlorophyll degradation occurred after a one-cycle treatment in any trees on any sampling date. Freezing cycles with sub-zero maxima and a -35 degrees C minimum enhanced winter injury in red spruce after a midwinter thaw had rendered the trees susceptible to freezing damage.

Anomalous temperature–growth response of Abies faxoniana to sustained freezing stress along elevational gradients in China’s Western Sichuan Province

“…Faxon fir trees are notably shallow rooting, with a large percentage of fine roots in the upper 30 cm (Schenk and Jackson 2002), and low winter-season temperatures may cause freezing injury to roots, promoted by frost penetration in the absence of adequate snow cover (Auclair et al 2010). Sakai and Larcher (1987) found that tree roots in northern hardwoods are by far the least affected by frost hardening of any tree tissue and can freeze at as little as -1°C, and the importance of soil frost as the foremost mechanism of dieback in northern hardwoods remains the most compelling explanation to date (Kullman 1991;Boyce 1995;Lund and Livingston 1999;Auclair et al 2010). Root kill exacerbates the effects of drought in the following growing season, and Faxon fir winter injury is caused by cold stress and (or) winter desiccation, which may result in the abscission of the most recent needles (Friedland et al 1984;Jalkanen et al 1998).…”

Management for red spruce conservation in Québec: The importance of some physiological and ecological characteristics – A review

“…Similar reductions in frost tolerance were observed by Strimbeck et al (1995) in mature trees. This rapid dehardening, unique to red spruce, is less pronounced if the period of thawing is brief (DeHayes et al 1990a, Perkins et al 1993 and if night-time temperature remains below 0°C (Hadley and Amundson 1992, Schaberg et al 1996, Lund andLivingston 1998). Therefore, periods of abnormally warm temperatures during the winter (DeHayes et al 1990a, DeHayes 1992, Hadley et al 1993b, followed by subfreezing temperatures (Strimbeck and DeHayes 2000), repeated freeze-thaw cycles (Lund and Livingston 1998) and direct sun exposure (Lazarus et al 2006) are frequent causes of frost damage.…”

Physiological and Environmental Causes of Freezing Injury in Red Spruce

“…Because red spruce grows in regions where air temperatures usually remain below O°C throughout the winter, extended thaws that allow melting and mobilization of water in the plant may stimulate precocious dehardening. Freezing injury would be expected if a prolonged thaw is followed by extreme cold or another form of cold stress resulting from temperature fluctuations, such as rapid freezing or repeated freeze-thaw cycles (Perkins and Adams, 1995;Lund and Livingston, 1998). Such environmental changes could conceivably lead to physiological impairment that may alter the phenological development and/or the full extent of cold tolerance achieved by northern montane red spruce trees, thereby increasing susceptibility to freezing injury.…”

“…That is, laboratory estimates more likely overestimate cold tolerance because the systematic and controlled nature of laboratory freezing conditions (e.g., slow and consistent rate of freezing and thawing) potentially represents a less stressful set of conditions than the natural environment, which includes a diverse and interacting set of environmental conditions and inconsistent fluctuations in ambient temperatures. Data from Lund and Livingston (1998), for instance, suggest that multiple freeze-thaw events, which are common under ambient conditions, may enhance the freezing injury susceptibility of red spruce. Thus, T, would be expected to be higher under ambient conditions in which temperatures fluctuated above and below freezing.…”