The status of Crumenula sororia infections in crops of Corsican pine

Nodal cankers caused by C. sororia on Corsican pine were three times as common as internodal cankers. Natural infections reached maximum incidence on the fourth internode from the apex in branches and stems, but on stem internodes only on the ninth internode down. The longitudinal rate of canker spread was approximately 4 times that of the tangential rate. Crops of Corsican pine on N-facing slopes were more severely infected than those on S-facing slopes or flat areas, but in all cases the frequency of infection increased progressively with crop age. Cankers on individual stems showed a highly significant concentration on Northerly and Easterly aspects. Evidence is presented which suggests that the temperature differentials observed on different sectors of tree trunks may influence the duration of water films and hence limit the time period during which spore germination is possible.     

Leaf Scale Traces in Corsican Pine

Discusses briefly a feature observed during an investigationof the structure of leading shoots of 1-year-old Corsican pine(Pinus nigra var. calabrica, Loudon). The feature, which doesnot appear to have been described previously in literature hasbeen tentatively called a ‘Leaf scale trace’.     

The Mode of Infection of Lodgepole Pine by Crumenula sororia Karst. and the Susceptibility of Different Provenances to Attack

Experimental inoculations of C. sororia on un-wounded Lodgepolepine produced successful infections after 9 months in 25 percent of cases, compared with 40–60 per cent where woundswere inoculated. After 16 months, however, these differencesdisappeared. The virulence of different isolates of C. sororiadiffered. Current year's shoots were more resistant to infectionthan 1-year-old shoots. Resistance was generally not a functionof broad geographical origin, save in the southern coastal types.Some provenances were highly significantly more susceptiblethan other closely adjacent ones: Burns Lake and Salmon Armwere highly susceptible, whereas Fort St. James and Mount Idaprovenances were respectively resistant. These observationsagree closely with field survey data, thus validating the useof young plants to indicate resistance of older crops to infection.     

Effects of nitrogen fertilization and temperature on frost hardiness of Aleppo pine (Pinus halepensis Mill.) seedlings assessed by chlorophyll fluorescence

In a 14-week study, 1-year-old Aleppo pine seedlings were grownin two growth chambers. Seedlings were artificially hardenedby decreasing photoperiod and temperature. In each chamber halfof the seedlings were fertilized with nitrogen (8.4 mg seedling^–1).In order to determine the relative importance of the hardeningenvironment versus fertilization, each chamber was programmedto decrease night temperatures down to a low of 8 or 4°C.Chlorophyll fluorescence and frost hardiness was measured fivetimes during the experiment. A sample of seedlings from eachtreatment was exposed to an artificial frost at –5°Cand the freezing effects were assessed by measurements of chlorophyllfluorescence and visual evaluation of needle damage. Seedlingsincreased their frost hardiness during the experiment in allthe treatments but the ratio of variable to maximal chlorophyllfluorescence (F_v/F_m) measured before freezing did not vary duringthe experiment. This indicates that Aleppo pine maintains itsphotosynthetic ability during hardening in contrast to otherconiferous species from colder climates. The effect of nitrogenfertilization on frost hardiness was small in comparison withchamber effect. Nitrogen fertilization slightly delayed theacquisition of hardening in the coldest chamber. Seedlings inthe warmest chamber did not become fully resistant to –5°C,but in the coldest chamber, where night temperature reached4°C, all the seedlings were resistant to the frost. Severedamage caused by frost could be related to a rapid rise of minimalfluorescence (F₀) but the best index of damage was the dropof F_v/F_m after freezing.     

Spring Frosts Affecting the Establishment of Second Rotation Crops in Thetford Chase

Spring frosts in Thetford Chase cause a major reduction in thegrowth of young Corsican pine and very severe frosts or repeatedfrosting may kill the trees. Records of temperatures taken ona range of sites and in different conditions have shown that(a) spring frosts occur every year at Thetford, but the severefrosts which kill trees outright may only occur once every fewyears, (b) frost damage to plants mainly occurs when the treesare less than 18 in (45 cm) tall, (c) forest clearings largerthan 5 acres (2 ha) do not act as artificial frost hollows,(d) cold air flows down slopes of more than 1° and accumulatesat the bottom, forming a frosty zone. Studies showed that frost damage can be minimized by (a) completecultivation, (b) deep ploughing, (c) underplanting, and (d)strip felling. The benefits of these measures are demonstratedby temperature records and by measurements of tree growth. Methods of reducing frost damage are necessary in areas proneto spring frosts if crops of Corsican pine are to be successfullyestablished at low cost.     

Seed pretreatments and nursery regimes for raising Macedonian pine (Pinus peuce Grisebach)

Four nursery experiments were carried out between 1984 and 1989to investigate ways of improving the germination and growthof Pinus peuce seedlings. In each of three germination experiments,the highest germination percentage was achieved with the longestduration of stratification. In the same experiments, bettergermination was usually achieved using alternating warm (c.20°C) and cold (2°C) pretreatments rather than coldpretreatment alone. The treatments that gave the best germinationwere generally those which provided the best height growth.In an experiment examining the effect of different nutrientsupon the growth of 1-year-old seedlings, height and root collardiameter were increased in the presence of nitrogen. However,these parameters were depressed by the presence of phosphate,potassium and magnesium.     

History of Peridermium Stem Rust of Scots Pine (Pinus sylvestris L.) in Thetford Forest, East Anglia

‘Peridermium’ stem rust (Peridermium pini (Pers.)Lev.) has been present in Thetford forest for at least 40 years,but has only become a major problem during the last decade.Survey data are presented which show that there has been a dramaticincrease in the disease in crops of Scots pine between 1964,when with less than one per cent of the trees showed symptoms,and 1979, when the figure was 10 per cent. The disease has apparentlyspread outwards from a central focus in the middle of the forest.In four plots the proportion of trees with visible symptomshas increased in five years from an average of 28 per cent to46 per cent. However, only 1–2 per cent of the trees havedied annually, and it appears that many trees with ‘deadtops’ may survive for long periods. The situation in Thetfordseems to contrast with that in north-east Scotland, where limiteddata suggest there has been no appreciable increase in diseaseincidence during recent years. There are only two records ofthe disease on Corsican pine (P. nigra var. maritima (Ait.)Melville) in Thetford.     

An investigation of the influence of harvesting practice on the development of blue-stain in Corsican pine logs

In September 1991, at Thetford, East Anglia and at Inverness,north-east Scotland, a comparison was initiated between blue-staindevelopment in Corsican pine logs from trees felled and processedby harvesting machine and similar logs from trees felled andtrimmed out by chain-saw. Blue-stain was assessed in discs from batches of logs destructivelysampled at 2-week intervals after felling. At the more southerlysite of Thetford, stain was first observed after 4 weeks. Themaximum recorded area was 10 per cent of the wood surface ina sample analysed after 10weeks. In contrast, stain never exceeded,1.1 per cent of the wood surface at Inverness. Amounts of stainwere significantly greater with machine-harvested logs thanwith chainsaw-harvested logs and were correlated with the amountof bark removed or loosened during harvesting. The use of spikedrollers resulted in more stain than did the use of rubber rollers. The fungi isolated from stained wood included Sphaeropsis sapinea,Potebniamyces coniferarum and Ceratocystis coerulescens. Theseare species adapted to the colonization of wood exposed throughdamage to the overlying bark     

Use of waste materials as nursery growing media for <Emphasis Type="Italic">Pinus halepensis</Emphasis> production

Peat moss is gradually being replaced by other materials as a growing medium in forest nurseries due to economic and ecological constraints. In this study, six different mixtures were tested, mixing peat moss (P) and pine bark (B) with digested sewage sludge (S) activated sewage sludge (A) and paper mill sludge (M), as growing media for Pinus halepensis seedlings; three different waste doses were applied. Seed germination percentage, seedling growth and foliar nutrient content after 1 year in a greenhouse and percentage survival after transplanting were recorded. The influence of base substrate (P or B) on germination percentage changed in different ways according the type of waste. The order of the different applied mixtures by suitability (germination rate and seedling growth) from best to worst was as follows: activated sludge with peat, activated sludge with pine bark, sewage sludge with peat, sewage sludge with pine bark, paper mill sludge with pine bark and finally paper mill sludge with peat.     

Vegetation and Environment in Afforested Sand Dunes at Newborough, Anglesey

Newborough Forest was planted with pines, chiefly Corsican pine,during the period 1947–65. In 1986, its soils and vegetationwere surveyed and related to the preplanting condition of thedunes, inferred from air photographs. The youngest dunes contained4 per cent calcium carbonate in the top 30cm; the oldest wereacid, with no free calcium carbonate. There was little acidificationof the soil and no extra leaching of calcium carbonate due tothe pines. Vegetation under trees varied according to the ageand pH of the dunes. Young dunes were almost bare except formoss; older dunes had been colonized by ferns and brambles.All plant species of the original open dune system had apparentlysurvived in unplanted slacks or on road verges; some had increased.Many new species had invaded, including woodland mosses, ferns,orchids and two species of Pyrola.     

The Effect of Drying Quercus robur Acorns to Different Moisture Contents, followed by Storage, either with or without Imbibition

Freshly harvested Quercus robur acorns were spread out, twodeep, in trays, and dried/stored (at +2°C over the courseof 28 weeks) to either 45, 40, 35, 30 or 25 per cent moisturecontent (fresh weight basis). Drying/storage significantly reducedthe germination percentage (P< 0.01). The acorns at eachmoisture content were then either ‘soaked’ or ‘notsoaked’, before immediate germination; or returned tothe same cold store at +2°C, this time in loosely tied polythenebags. Soaking raised the acorns moisture content (M.C.), andalso brought about a significant increase in germination capacity(P<0.01). Regardless of the moisture content immediatelybefore soaking, "soaked" acorns in loosely tied polythene bagsstored better than ‘unsoaked’ acorns. All ‘bagged’acorns (whether ‘soaked’ or ‘unsoaked’)stored better than acorns dried/stored in open trays.     

The lichens of the Scottish native pinewoods

During the last 30 years, 434 epiphytic lichen taxa have beenrecorded from the native pinewoods of Scotland. Of these lichens,about 219 have been recorded from the bark, lignum or stumpsof pine (Pinus sylvestris) itself. Eighteen species are, inthe British Isles, confined to these native pinewoods, whichare themselves confined to the Scottish Highlands. A resumeis presented of the habitats and niches available to lichensin the native pinewoods, using examples of the most characteristicspecies for each. The ‘pinewood habitat’ for epiphyticlichens is by no means restricted to pine, but also includesassociated trees, shrubs and subshrubs, especially birch, rowan,holly, aspen, juniper and heather. The strong east–westvariation in the composition of the lichen flora is outlined.By comparison of species lists from pinewood stands of knownancientness with those from mature plantations distant fromthe ‘core’ pinewoods, an additional c. 60 speciescan be considered as indicative of an ecological continuityof the pinewood habitat. From this pool of c. 77 species, aNative Pinewood Index of Ecological Continuity is presentedas a useful tool for biodiversity assessments of pinewoods.     

The prediction of Crumenulopsis sororia (Karst.) Groves. Incidence on lodgepole pine (Pinus contorta Dougl.) using multiple regression techniques

Easily-measured site variables (e. g. absolute elevation, exposure, slope and aspect) were used to prepare different regression models to predict the extent and severity of attack by C. sororia on a number of different provenances of lodgepole pine. Using a simple climatic-zone division of Scotland, a significant relationship between percentage infection on whorls 1–5, 6–10 and 11–15 and elevation, exposure and site aspect was demonstrated, whereas severity of infection was not well related with these variables in any of the models tested. This suggests that severity of infection may be influenced by other independent variables, e. g. persistence of liquid water on bark, success of spore germination and host resistance. This approach offers an opportuity to predict the possible susceptibility of different provenances of lodgepole pine under specific site conditions.     

CONIFEROUS LITTER AMENDMENTS AND THE GROWTH OF SITKA SPRUCE

The growth of semi-checked Sitka spruce (Picea sitcbensis Carr.)on heathland has been stimulated to different degrees by theannual application of litter of Scots pine (Pinus sylvestrisL.), Corsican pine (P. nigra var. calabrica Schneid), Lodgepolepine (P. contorta Dougl.), Japanese larch (Larix leptolepisGord.), and Sitka spruce, at rates corresponding to normal plantationconditions, following an initial heavier rate. Foliar analysissuggests that the response is at least partially attributableto the influence of the litters on the nitrogen nutrition ofthe spruce and differences between litters appear to be largelydetermined by their total nitrogen contents. In this respect,Japanese larch, with an annual needle fall generally greaterthan that of the pines and a higher nitrogen content, offersthe best promise as a nurse species for spruce.     

Effect of the Needle-cast Fungus Lophodermella sulcigena on Growth of Corsican Pine

Infection of current-year needles of Corsican pine near Aberdeenby Lophodermella sulcigena (Rostr.) v. Höhn. resulted ina 59 per cent reduction in the volume growth of the stem overa 12-year period; height increment was not affected significantly.     

The Influence of Soil Type and Pine Species on the Carabid Community of a Plantation Forest with a History of Pine Beauty Moth Infestation

The community composition of Carabid beetles, some species ofwhich are known predators of pine beauty moth, was examinedwithin a Scottish plantation forest. Sites differing in soiltype and the species of trees planted were sampled with pitfalltraps in most weeks of a 3—year period. There were faunaldifferences between sites with lodgepole pine on deep peat andother sites in the study (lodgepole pine on iron-pan soil, speciesmixture of lodgepole and Scots pine, and pure stands of Scotspine). In general deep peat sites supported fewer species andindividuals of carabids. Three Carabus species were implicatedas likely predators of Panolis flammea pupae and each was lessabundant on the sites with lodgepole pine. It is suggested thatthe susceptibility to pine beauty moth of lodgepole pine growingon deep peat substrates is at least partly attributable to impoverishedpredator faunas.     

Stem volume equations and basic density for grey alder and common alder in Sweden

The objective was to determine stem volume models for grey andcommon alders and, based on the models, stand volume for naturallyregenerated grey and common alder stands was summarized. Basicdensity for grey and common alders and mean annual growth forstands was estimated. Net volume accretion data were collectedfrom 24 stands of grey alder (Alnus incana (L.) Moench) and31 stands of common alder (Alnus glutinosa (L.) Gaertner) inSweden. The stands ranged in latitude from 58 to 64° N andfrom 56 to 62° N for grey and common alder, respectively.The mean age of grey and common alder stands was 41 years and48 years, respectively, the mean stand density 1726 stems ha^–1and 1078 stems ha^–1, and the mean diameter at breast height(over bark) was 20 cm and 21 cm. Stem volume equations weredeveloped for grey and common alders. The adopted model forgrey alder was based on diameter at breast height and height.For common alder, crown height was added to diameter and height.Mean standing volume (over bark) for grey and common alder standswas 428 and 374 m³ ha^–1. Mean annual growth for grey andcommon alder stands was 12.0 m³ and 8.4 m³ a^–1 ha^–1,respectively. Basic density (under bark), for grey and commonalder stems was 359 and 427 kg m^–3, respectively. Thebasic density (under bark) for the lowest twigs in the crownand in the lateral part of the crown was 415 and 421 kg m^–3for grey alder and 423 and 423 kg m^–3 for common alder.     

Incidence and importance of Crumenula sororia on Lodgepole pine

In stands of Lodgepole pine over 6 years old, 68% of stems in Climatic Zones A and B, characterised by a relatively short growing season, and 63 % of stems in Climatic Zone C were infected by Crumenula sororia. On individual trees, the number of stem whorls showing C. sororia infection increased significantly with increasing stand elevation and with decreasing exposure in crops on Alberta and Shuswap Lake provenances over 30 years old, whereas in Shuswap, Long Beach and Vancouver Island stands less than 30 years old, increasing elevation and decreasing exposure had little effect on numbers of infected whorls. The numbers of infected whorls were not related to compartment aspect in crops of Alberta provenance, whereas in stands of Shuswap Lake, Long Beach and Vancouver Island provenances, W, SW and S-facing compartments showed fewer infections. In contrast the numbers of active cankers showed a positive correlation with increasing compartment elevation and exposure. In Zones B and C, cankers were concentrated on Northerly and Westerly aspects of individual stems. The evidence suggests that particular climatic regimes in different zones of the tree and in different ages of crop may be critical in determining the success of failure of infection by C. sororia.     

Dimensional changes in Corsican and Scots pine sapwood due to reaction with crotonic anhydride

 The effects of the reaction temperature and varying level of weight gain on the dimensional stabilisation of crotonic anhydride modified Corsican and Scots pine sapwood were investigated. With Corsican pine at low levels of substitution, the reagent occupied larger molar volumes in the cell wall than at higher weight gains. With Scots pine the molar volume occupied by reagent was found to be temperature dependent at low levels of substitution. Dimensional stabilisation was determined by the water-soak/oven-dry method through a total of ten cycles in order to determine the stability of the ester bond to hydrolysis at neutral pH. It was found that the reaction temperature has no significant effect on dimensional stability provided the same weight gain level is obtained. At weight gain levels in excess of 30%, values of anti-shrink efficiency of 90% were obtained. Received 2 April 1999