Seasonal Changes in the Frost Hardiness of Provenances of Picea sitchensis in Scotland

Changes in the natural level of frost hardiness of shoots offour provenances of Picea sitchensis were monitored over twogrowing seasons by detaching shoots from 7 to 10-year-old treesgrowing in a nursery in Scotland, and subjecting them to freezingtemperatures under conditions which simulated night frosts. Six seasonal phases of frost hardiness were identified (Fig.3).

1. During each autumn, killing temperatures (the level of hardiness)decreased from –5°C to below –20°C, beginningseveral weeks after shoot elongation ceased. Alaskan provenanceshardened in September, apparently in response to shorteningday lengths alone, whereas an Oregon provenance did not hardenuntil November, after repeated frosts. Queen Charlotte Islandsprovenances were intermediate.
2. From November to March allprovenances were hardy to below –20°C,which is adequateto prevent direct freezing injury at mostplantation sites.
3. In March-April, several weeks before bud-burst, old shootsdehardenedto killing temperatures of about –10°Cin responseto warm temperatures, and southerly provenancesdid so beforenortherly ones.
4. During bud-burst the newly-emergingshoots were hardy to only–3°C to –5°C untilthey were about 3.5 cmlong. All provenances burst bud at thesame time and were equallyfrost susceptible at this time.
5. DuringMay-July the elongating shoots fluctuated in hardinessbetween–5°C and –10°C apparently in responsetofluctuating ambient temperatures.
6. In August 1980 there wasa period of late summer dehardeningto killing temperaturesof about –3°C.

Seasonal changes in hardiness are discussed in relation to changesin shoot growth and environmental factors. The main opportunitiesfor selecting frost hardy genotypes seem to be in the rate ofautumn hardening, the time of pre-bud burst dehardening, andthe time of bud-burst.     

Autumn Frost Damage on Young Picea sitchensis 2. Shoot Frost Hardening, and the Probability of Frost Damage in Scotland

The natural increase in frost hardiness of detached shoots ofPicea sltchensis during August to November was measured usinga programmable freezing chamber. Oregon, Queen Charlotte Islandsand Alaskan provenances were compared, and the effects on hardeningof long days, warm temperatures and frosts were determined.A computer model was constructed to mimic the observed patternsof autumn frost hardening, as functions of air minimum temperatures,daylengths and the occurrence of frosts. The model was used(a) to describe the pattern of autumn frost hardening at differentsites in northern Britain, using past meteorological records,and hence (b) to determine when frosts occurred that might havedamaged young trees. The model accurately predicted known instancesof autumn frost damage at Kirroughtree and Carnwath. The predicted probability of autumn frost damage on young treesof P. sitchensis in upland areas of Scotland was much lowerthan that previously predicted for spring frost damage. Theestimated return time for autumn frost damage to an Oregon provenanceat Eskdalemuir was 8.3 years, and the return time for a Q.C.I.provenance was longer than 10 years. Most damaging frosts occurredin October, but frosts like those on 13–15 October 1971,which followed warm weather and caused wide spread damage inScotland, have been quite rare. Alaskan provenances would rarelybe damaged by autumn frosts, nor would trees of Q.C.I. provenancegrowing in lowland areas of Scotland, or at Masset on the QueenCharlotte Islands.     

Autumn Frost Damage on Young Picea sitchensis 1. Occurrence of Autumn Frosts in Scotland compared with Western North America

Dates of first autumn air frosts (in Stevenson screens) of –2.5°Cand 4.5°C were obtained for 42 meteorological stations innorthern Britain with runs of 18 to 116 years. Frequency distributionsof first frost dates were approximately normal. Altitude, distancefrom the sea, latitude and distance from the NWSE axis of Britaintogether accounted for 75% and 81% of the variation in datesof first –2.5°C and –4.5°C frosts, respectively,at the 42 stations. The variance in dates of first frosts decreasedfrom lowland coastal to upland inland sites. Multiple regressionswere used to produce maps of first frost dates in 20 x 20 kmgrid squares of Scotland. Dates of first 28°F (–2.2°C) and 24°F (–4.4°C)frosts were obtained for 20 sites in western North America,spanning the natural range of P. sitchensis. Mean dates wereearlier, and variances decreased, from south to north. Upland sites like Eskdalemuir and Kielder Castle experience–2.5°C and –4.5°C frosts earlier in theautumn than all coastal stations in western North America southof about latitude 58°N (between Cordova and Sitka), andabout 4 weeks earlier than at Masset on the Queen CharlotteIslands. Thus, P. sitchensis from Q.C.I. and further south mayoften experience autumn frosts in Scotland before the treeshave experienced the cool/short days that they require to inducefrost hardening.     

Spring Frost Damage on Young Picea sitchensis 1. Occurrence of Damaging Frosts in Scotland Compared with Western North America

Air frosts (in Stevenson screens) of –2.5°C or belowin Scotland were judged to be potentially damaging to the newlyemerging shoots on young trees of Picea sitchensis at the timeof budburst. This was based on a knowledge of the killing tissuetemperature and the relationship between air and grass minimain May. Dates of last spring air frosts of –2.5°C and –4.5°Cwere obtained for 42 meteorological stations in northern Britainwith runs of 19 to 116 years. Frequency distributions of lastfrost dates were approximately normal. About 80% of the variationbetween stations could be attribuoted to altitude, distancefrom the sea and latitude. The variance in last dates of –2.5°Cfrosts decreased from mild to cold sites. Multiple regressionswere used to produce maps of last frost dates in 20x20 km gridsquares in Scotland. Dates of last 28° F (–2.2°C) and 24°F (–4.4°C)frosts were obtained for 20 sites in western North America,spanning the natural range of P. sitchensis. Mean dates increased,and variances decreased, from south to north. Most Scottish upland plantation sites (e.g. Glentress and Eskdalemuir)experience –2.5°C air frosts until later in the yearthan all coastal stations in western North America south ofCordova, Alaska. On average, Eskdalemuir (242 m altitude) experiences–2.5°C air frosts about 4 weeks later in the springthan Masset (3 m) on the coast of the Queen Charlotte Islands,which has been the source of much of the P. sitchensis plantedin Scotland. Masset has a spring frost climate somewhat milderthan Durham.     

Winter Frost Hardiness of two Chilean Provenances of Nothofagus procera in Scotland

The frost hardiness of the shoots of individual trees withintwo Chilean provenances of Nothofagus procera (Poepp & Endl.)Oerst. was measured once in each of the months January, February,November and December 1989 and January and February 1990. Therewere significant (P<0.05) differences of frost hardinessbetween provenances but only one tree could be shown to be significantlymore frost hardy than the others within the same provenance.During the winter of 1989/90 both provenances were hardy toabout –14°C (temperature killing 50 per cent of shoots)in December, but the shoots dehardened to about –9°Cin January before hardening again in February. This patternof alternate hardening and dehardening seemed to mirror changesin air temperature and could render N. procera liable to frostdamage where (as happened in 1988/9 in the UK) mild spells occurin winter followed by severe frosts.     

Spring Frost Damage on Young Picea sitchensis 2. Predicted Dates of Budburst and Probability of Frost Damage

The probability of frost damage at the time of budburst on thelateral shoots of young trees of Picea sitchensis in Scotland,and at Masset on the Queen Charlotte Islands, was determinedfrom (a) the dates of budburst, predicted from past temperaturerecosds using a thermal time / chilling model, and (b) the datesof last air frosts of –2.5°C. The mean date of budburst occurred between 6 and 13 May at arange of Scottish sites up to about 250 m altitude, but it occurredabout 6 days later for each further 100 m increase in altitudeup to 550 m. This resulted from an interplay between chillingand thermal time requirements for budburst. In different years,budburst dates ranged from mid-April to early June. From 1920to 1960 there was a trend towards warmer springs and earlierdates of budburst, which has been reversed since 1960. Potentially damaging frosts have occurred near the date of budburstonce every 3 years (on average) at Eskdalemuir and Braemar duringthe last 66 to 107 years, and once every 3 to 5 years in manyupland plantation regions of Scotland. The probability of damagingfrosts was greatest in the period 1930 to 1960 when budburstoccurred relatively early, and has been relatively small since1960, because budburst has occurred relatively late. Renewedwarming of the climate in future may increase the probabilityof damaging frosts coinciding with the time of budburst. Masset, on the Queen Charlotte Islands, from where Britain hasimported most P. sitchensis seed, has relatively cool springsso that budburst occurs relatively late (averaging 18 May).Also there are few damaging frosts at Masset after late April.Consequently, potentially damaging spring frosts have occurredthere only once in 65 years.     

Phenotypic Differences Between Natural and Selected Populations of Picea Abies. I. Frost Hardiness

The frost hardiness of non-juvenile Norway spruce [Picea abies (L.) Karst.] populations growing in northern Sweden (63°54' N) was monitored during 1996-1997. The investigated progenies originated from 12 natural populations and six seed orchards located between 58° N and 68° N in Sweden. Frost hardiness of needles was assessed by measuring chlorophyll fluorescence and electrolyte leakage after freezing. The loss of frost hardiness in 1-yr-old needles during spring occurred slightly earlier in populations originating north of 63°30' N than in those originating further south. Dehardening was slightly delayed in selected populations compared with natural populations of similar origin. The level of frost hardiness during autumn was higher in populations originating north of 63°30' N than in those originating south of this latitude, but there were no clear differences in frost hardiness between selected and natural populations of similar origin. The results are discussed in relation to climatic factors and inherent growth rhythms.     

Mechanical Properties of Picea sitchensis

This study establishes the basis for the assignment of Danish - grown Sitka spruce (Picea sitchensis) to the European strength class system (EN 338). In total, 712 boards were chosen to be representative of the normal Danish commodity. These were visually graded for strength according to Nordic rules (INSTA 142), and subsequently tested to failure in either bending or tension. The results show that Danish - grown Sitka spruce graded to levels T1 and T2 satisfy the requirements of EN 338 at the C18 and C24 levels, respectively. Results for Danish - grown Sitka spruce concur with those for Danish - grown Norway spruce (Picea abies). This study shows that Sitka spruce and Norway spruce of similar origins exhibit highly comparable mechanical properties.     

Frost tolerance of two-year-old Picea glauca seedlings grown under different irrigation regimes in a forest nursery

Abstract

This study examined the impact of increased irrigation efficiency on the hardening and frost tolerance of 2-year-old containerized white spruce seedlings in the context of groundwater protection, irrigation management and the maintenance of seedling quality in northern climates. The seedlings were grown under three different irrigation regimes (IR =30%, 40% and 55% v/v; cm³ H₂O/cm³ substrate) and were hardened under conditions of natural photoperiod and temperature. After being subjected to artificial frost tests on four sampling dates during autumn, the seedlings were compared for bud development and frost tolerance. IR had no influence on frost tolerance as determined by measurements of physiological (electrolyte leakage, root water loss) and morphological (shoot damage, root initiation) variables. At the end of the second growing season, there was no significant difference between IRs in seedling height, root collar diameter, shoot dry mass and root dry mass. The results indicate that the amount of water applied to large-dimension 2-year-old white spruce seedlings during the growing season can be significantly decreased without prematurely impeding their growth or hindering their acquisition of frost tolerance.     

Dynamics of swaying of Picea sitchensis

Six 26-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) trees growing in a Scottish plantation were swayed manually to determine their mechanical dynamics. The natural frequency of sway of the intact trees (mean height 14.2 m and mean stem diameter 14.5 cm at 1.3 m) was on average 0.35 Hz. The variation of this frequency with tree size was found to be well described by engineering mechanics theory. In particular, shape parameters could be defined for both intact and branchless trees, which, along with stem size, density and elasticity, could predict the natural sway frequency using a simple formula. The damping of sway was found to consist of three components, (1) interference of branches with those of neighbors, (2) aerodynamic drag on foliage, and (3) damping in the stem. For the sample of six trees, which spanned the diameter range at the experimental site, the importance of these three components to overall damping was in the ratio 5/4/1 for the median sized tree. Interference between neighbors depended on the distance to neighbors, as well as on the sizes of the chosen tree and its neighbors. Aerodynamic damping was larger for larger trees and the energy lost to this force was similar in magnitude to that calculated to be lost using drag coefficients from published wind tunnel and other studies. The amount of damping from the stem was linearly related to stem diameter.     

Frost Hardiness of Subalpine Eucalypts in Britain

Laboratory freezing tests were used to determine seasonal changesin the frost hardiness of detached shoots of young trees ofEucalyptus gunnii (from central Tasmania), and E. niphophilaand E. debeuzevillei (‘snow gums’ from the SnowyMountains, Australian Capital Territory). The trees were growingat the Bush Estate. No difference was found between the speciesor between seedlots, all of which were from high altitudes nearthe tree line. In midwinter (February) the shoots tolerated –16°Cwithout suffering damage, and many shoots survived temperaturesas low as –18°C to –22°C. This result agreedwith Evans' (1986) observation that some trees within theseseedlots survived temperatures in the range –19°Cto –23°C in field planting during the winter 1981/82.In their native habitats the trees rarely experience temperaturesbelow –20°C. The shoots did not harden appreciably before they experiencedfrosts (in late October/early November) and so may be proneto autumn frost damage. By contrast, they were slow to dehardenin late winter and spring and did not seem prone to spring frostdamage. There were no killing air frosts during the period of this study(winter 1985/6), but many trees died, possibly as a result ofground freezing, producing root injury and/or shoot desiccation.In subalpine regions of Tasmania and the Snowy Mountains theground is covered by snow throughout the winter. Variation in frost hardiness within these hardy seedlots couldbe exploited.     

经济植物的抗寒性研究进展

综述了植物抗寒研究的新进展。植物在低温下的抗寒生长过程中，其形态结构及其超显微结构发生变化．膜脂的成分及蛋白质数量和种类也发生改变；植物的抗寒生理生化的变化是通过低温改变基因表达而引发的，在抗寒中起作用的基因已经识别出来，并且已经了解这些基因的作用方式．ABA和PP333等外源激素和钙离子能诱导植物体内的ABA水平提高，从而增强植物的抗寒能力。但诱导机理仍待研究。     

Observations on bark-stripping by red deer in a Picea sitchensis forest in Western Scotland over a 35-year period

The impact of bark-stripping by red deer on an 1825?ha plantation of Picea sitchensis is reported. Monitoring began in 1978 with initially 6500 trees at 37 sites; by 2014, only 10 sites remained due to felling. Sites became vulnerable to bark-stripping once the trees reached 7 years’ age, and from then until felling at age c. 45 years, incidence rates averaged 1% of the trees damaged yearly. Intense damage at a site in a year (>2% trees damaged) was often followed by intense damage next year, but, on average, 53% of sites were undamaged in a year. Many trees suffered repeat wounding, which reduced final impact by c. 30% compared to the theoretical impact calculated from annual damage and damage duration. The trees bark-stripped were on average smaller than plot mean girths once these means exceeded 20?cm; this had only a minor effect on the final impact since bark-stripped small trees had similar mortality to undamaged small trees. Most wounds (>90%) were small (<180?cm²) and healed quickly, so were unlikely to develop decay. Larger wounds never healed in less than 8 years, but the proportion healed increased progressively from 10 to 20 years after wounding.     

西加云杉木材中单宁的提取、分布及组分

研究西加云杉木材中植物单宁的提取工艺、分布和组分构成,为木材单宁变色的防治提供参考.采用有机溶剂萃取法,通过单因素试验并结合L9(34)正交试验,优化西加云杉木材中植物单宁的提取工艺;采用香草醛-紫外法测定西加云杉木材内植物单宁在径向(由髓心至树皮方向)和轴向的含量分布;通过定性鉴定试验确定单宁类型,并采用高效液相色谱...     

Organogenesis and embryogenesis in mature zygotic embryos of Picea sitchensis

Differentiation of adventitious buds and somatic embryos from mature zygotic embryos of Picea sitchensis (Bong.) Carr. is described. Adventitious buds were formed on embryos pulse-treated with 250 microM benzyladenine for 2 h and cultured on medium lacking growth regulators. Buds were initiated at different frequencies and sites depending on when the BA-pulsed embryos were transferred to fresh culture medium. Embryogenic callus was formed when the zygotic embryos were cultured on medium containing 10 microM 2,4-dichlorophenoxyacetic acid and 5 microM benzyladenine. Although 50% of the embryos gave rise to embryogenic callus, only 20% of the callus continued to proliferate after subculture. Proliferation of new somatic embryos occurred from both the embryonic region and the suspensor region on previously formed somatic embryos. The pattern for development of adventitious buds and somatic embryos in Picea sitchensis is compared to that in Picea abies under similar culture conditions.     

Elevated temperature during reproductive development affects cone traits and progeny performance in Picea glauca x engelmannii complex

Two temperature regimes were applied during reproductive development of seed and pollen cones of interior spruce (Picea glauca (Moench) Voss and Picea engelmannii (Parry) complex) to determine temperature effects on the adaptive traits of progeny. In Experiment 1, identical crosses were made on potted interior spruce using untreated pollen followed by exposure to a day/night temperature of 22/8 or 14/8 degrees C with a 12-h photoperiod during the stages of reproductive development from post-pollination to early embryo development. Frost hardiness and growth of progeny from seed produced in the two temperature treatments were measured over a 4-year period. Elevated temperature significantly affected both seed-cone development and the adaptive properties of the progeny. Seed cones exposed to the 22/8 degrees C treatment reached the early embryo stage in 53 days versus 92 days in the 14/8 degrees C treatment. Seed yields, cotyledon emergence and percent germination were also significantly enhanced by the 22/8 degrees C treatment. Progeny from seed produced in the higher temperature treatment showed significantly reduced spring and fall frost hardiness, but the elevated temperature treatment had no significant effects on time of bud burst, growth patterns or final heights. In Experiment 2, single ramets of the same clone were subjected to a day/night temperature of 20/8 or 10/8 degrees C during pollen cone development, starting from meiosis and ending at pollen shedding. The two populations of pollen were then crossed with untreated seed cones. Compared with pollen cones exposed to the 10/8 degrees C treatment, pollen cones exposed to the 20/8 degrees C treatment during development reached the shedding stage 2-4 weeks earlier, whereas pollen yields, in vitro viability and fertility (seed set) were significantly lower; however, the resulting progeny displayed no treatment differences in frost hardiness or growth after 1 year. Results suggest that seed orchard after-effects could be caused by temperature differences between orchard site and parent tree origin and that this effect acts on maternal development. Gametophytic (pollen or megagametophyte or both) and early embryo (sporophytic) selection are possible mechanisms that may explain the observed results. Although the effects are biologically significant, they are relatively small and do not justify changes in current deployment strategies for seed orchard seed.     

Frost Hardiness of Nothofagus procera and Nothofagus obliqua in Britain

The frost hardiness of four seedlots of Nothofagus proccra andsix seedlots of Nothofagus obliqua was measured experimentallyduring three winters. Shoots were taken from saplings growingat the Bush Estate in Scotland. All seedlots set buds in lateSeptember, hardened very slowly in the autumn, were damagedto some extent by temperatures below –14°C in mid-winter,and dehardened during frosty weather in February/March priorto budburst in mid to late April. The range of mid-winter temperaturesgiving 0%, 50% and 100% kill (LT₀, LT₅₀ and LT₁₀₀) were 8–14°C,13%20°C and 14–22°C, respectively. By contrast,British Fagus sylvatica hardened off rapidly in September, wasundamaged by frosts well below –20°C in mid-winter,and did not deharden until late April, prior to budburst atthe end of May. Nothofagus seedlots from Nuble in Chile (the most Equatorialsource) were the most frost susceptible: unfortunately, seedof this origin was supplied to many British nurseries between1976 and 1W9. Seedlots from Neuquen in Argentina, and from maturetrees of Malleco (Chile) origin growing in Britain, were themost host hardy. N. procera tended to be hardier than N. obliqua,and the trees became hardier with age. Past temperature records for Britain suggested that all theNothofagus seedlots had a high risk of suffering severe frostdamage at least once during a timkr rotation in all but mildcoastal regions. Spring and autumn frosts may be more damagingthan winter frosts. However, if it were possible to select individualswithin populations that were 3–6°C more frost hardythan the population means, such trees would be sufficientlyhardy to avoid frost damage in most lowland regions.     

Relationships between Growth of Sitka Spruce (Picea sitchensis), Soil Factors and Mycorrhizal Activity on Basaltic Soils in Western Scotland

A survey was made of soil factors likely to be responsible forchecked growth of Sitka spruce on soils derived from basaltin western coastal areas of Scotland. Despite the high organicP contents of these soils, availability of P appears to be themain factor limiting growth; growth indices were significantlycorrelated with foliar P concentrations and inorganic P levelsof the soil. The low availability of soil P appears to be associatedwith high levels of oxalate-extractable Al (amorphous) in thesoils, a strong correlation existing between the latter andthe P sorption index of Bache and Williams. CaCl₂-extractableAl (‘available’) values were also high and althoughthey exhibited no significant correlation with growth therewas a negative correlation between growth and foliar Al concentrations. High mycorrhizal counts were associated with tree roots on siteswith better growth while beaded roots were mainly associatedwith poor growth. There is a suggestion that high CaCl₂-extractableAl in these soils may affect mycorrhizal development, as a strongcorrelation was found between the occurrence of beaded rootsand foliar Al concentration. Factor analysis confirmed that low availability of P in thesesoils may be ameliorated by mycorrhizal development and thata negative association exists between growth, the occurrenceof beaded roots and foliar Al concentration.     

白云杉扦插育苗技术的研究

采用拱棚覆膜、上盖遮阳网的扦插育苗方法,进行白云杉嫩枝与硬枝扦插育苗试验,结果表明,在沈阳周边地区的气候条件下,以IBA 200 mg/kg浸插条90 min,扦插成活率83%,生根率可达85%,且根系发育好,移栽成活率高;嫩枝插条生根率比硬枝插条生根率高57%,两种插条生根率差异达到显著水平;插条在细河沙上的扦插成活率比在木屑上的高20%,生根率提高21%。嫩枝插条扦插后,20 d形成愈伤组织,30 d出现凸起,45 d生根。秋季控水炼苗,冬季床上覆膜覆草越冬。翌年移植成活率可达90%,当年新梢生长量5.5 cm。     

美国西加云杉出国考察报告

简要介绍了西加云杉的生物生态学特性及其生境条件 ,并提出了该树种引种的研究方向。