Frost damage to eucalypts in a short-rotation forestry trial in Cumbria (England)

Abstract

© iForest -Biogeosciences and Forestry IntroductionShort rotation forestry (SRF) involves growing trees in plantation at a spacing that allows rapid site capture and which are then harvested at a dbh of between 10 and 20 cm (Hardcastle 2006). The wood produced is normally used to substitute fossil fuels as a source of energy. A number of hardwoods were identified as having potential for SRF in the UK (Hardcastle 2006), but the Read Report (Read et al. 2009) highlighted the potential of eucalypts in sequestration of atmospheric carbon, due to their rapid growth. Of these, two species were identified as having particular potential for the UK: Eucalyptus gunnii Hook.f. It is cold that presents the greatest limitation to growing eucalypts in the UK (Leslie et al. 2012). Low temperatures have two main negative impacts on the photosynthesis of eucalypts. The first is damage to tissues due to rupture of cells, while the second is photoinhibition of photosynthesis (Davidson et al. 1995). Photoinhibition involves a decrease in the efficiency of photosystem II through the combination of cold temperatures and high levels of sunlight (Close & Beadle 2003). Photoinhibition occurs least and recovery is most rapid in the most coldtolerant eucalypts (Hovenden & Warren 1998).Furthermore, low soil temperatures are known to decrease absorption of water by roots (Teskey et al. 1984, in Cochrane & Slayter 1988. When the soil is frozen uptake can be seriously disrupted; generally, soil temperatures of -1 °C or less will prevent water uptake and can increase dehydration (Larcher 1957, in Boyce & Lucero 1994. During periods of warm air temperatures with frozen ground, trees must rely on moisture stored in sap reserves and smaller trees will deplete these reserves faster (Boyce & Lucero 1994).Eucalypts have four main ways of producing leafy shoots; naked buds in leaf axils, accessory buds, dormant (epicormic) buds and buds in lignotubers. The latter two, dormant and lignotuber buds are particularly important in producing shoots after significant damage, such as fire or frost. However, it is the naked buds and accessory buds that normally contribute to crown development. The naked buds primarily contribute to the development of leafy shoots, with accessory buds providing an alternative if the naked buds are damaged (Jacobs 1955, in Commonwealth Government of Australia 1999). The naked buds grow when temperatures are above a certain minimum, enabling potentially high productivity, especially when grown as exotics as this strategy allows growth through much of the year. Unlike most temperate trees, photoperiod has no effect on growth (Paton 1983). Davidson et al. (1995) note that maximum winter growth rates for E. nitens (Deane and Maiden) Maiden in a plantation in Tasmania were only slightly less than maximum rates in summer. However, this lack of dormancy also leaves eucalypts vulnerable to damage through chilling (Davidson et al. 1995). The cold winters experienced in the UK, relative to those of Australia, means that only a limited ra...

A resource capture efficiency index to compare differences in early growth of four tree species in northern England

“…The native and naturalised broadleaves were able to cope with these conditions, but the eucalypts fared badly, particularly the less cold-tolerant shining gum which exhibited complete mortality over each of the two severe winters. An analysis of the cold damage at the trial is described in Leslie et al (2014). Eucalypts have been planted on a limited extent in the UK; between 2011 and 2016 nurseries sold 220,000 transplants (Purse & Leslie 2016b) and this scale represented trial rather than commercial planting.…”

A review of the suitability of eucalypts for short rotation forestry for energy in the UK

“…Furthermore, coppice rotations are more productive than first-rotations (Pukkala and Pohjonen 1990). A further approach to reduce damage is the use of intensive silviculture to accelerate establishment and growth as larger trees are more resistant to cold than smaller ones (Leslie et al 2014a). Finally, to reduce the risk of complete failure, plantations should comprise stands reflecting the full range of ages, from those recently established to those of rotation age, as younger stands are more susceptible to damage from cold.…”

Special trends in CBF and DREB2 groups in Eucalyptus gunnii vs Eucalyptus grandis suggest that CBF are master players in the trade‐off between growth and stress resistance

“…Eucalyptus gunnii comes from temperate Tasmania, in contrast to E. grandis , the first sequenced Eucalyptus species (Myburg et al ), which is found in subtropical areas. E. gunnii is known as one of the most cold tolerant Eucalyptus species (Leslie et al ), but it is much less productive than E. grandis . They are therefore very representative of the apparent trade‐off between growth and stress resistance observed among the very diverse species of the genus Eucalyptus , with the most productive being the least hardy.…”

“…They are therefore very representative of the apparent trade‐off between growth and stress resistance observed among the very diverse species of the genus Eucalyptus , with the most productive being the least hardy. Unlike most temperate trees, Eucalyptus growth is regulated by temperature rather than photoperiod (Leslie et al ), and a trade‐off between freezing resistance and growth mediated through xylem vessel anatomy has already been shown for overwintering evergreens, including Eucalyptus species (Choat et al , Maseda and Fernandez , Silva et al ). For this study, it was necessary first to identify the CBF and DREB2 genes from E. gunnii, the genome sequence of which is not publicly available.…”