The silviculture of conifers in Great Britain

The original paper by H.M. Steven, with this title, describedthe silvicultural characteristics of the main coniferous speciesthen available in British forestry. The use of these introducedconifers was justified by the limited site tolerances of theone native species, Scots pine, and the need to expand forestcover on to sites with infertile soils in harsh climatic conditions. This paper reviews the developments in silvicultural techniquesand understanding that have enabled the rapid expansion of productiveforestry in the last seventy years:

• The problems associated with afforestation, requiring ameliorationof soil physical and chemical conditions, have been resolvedand the climatic limits to the use of individual species aremore clearly defined.
• Increased knowledge of the physiologicalresponses of individualspecies to environmental factors hasinfluenced silviculturalpractice from nursery production tothe regeneration of maturestands.
• Analysis of genetic variationwithin introduced conifer specieshas refined their use andis leading to improvements in theirproductivity and timberquality.
• The application of ecological principles, based onthe ecosystemconcept, has led to an understanding of foreststand dynamicsthat should ensure production from exotic specieson a sustainablebasis.

Future requirements in the silviculture of conifers includethe transferof the results of computer simulation modellinginto practice, the developmentof silvicultural systems appropriateto British conditions and greater emphasis on the quality ofproduction.     

An outbreak of malignant catarrhal fever in young rusa deer (Cervus timorensis)

On the basis of clinical signs and histological findings eight 9-month-old male rusa deer ( Cervus timorensis ) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5°C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested poly-merase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer.     

Peripheral blood lymphocyte subsets in fleece rot-resistant and -susceptible sheep

Objective To compare haematological values and lymphocyte phenotypes in the peripheral blood of fleece rot-resistant and -susceptible sheep.
Procedure Experiments were conducted on 2- and 3-year-old Merino rams, flock 1 (17 rams) and flock 2 (32 rams), respectively. Within each flock, individual rams were classified as fleece rot-resistant or -susceptible, based on established criteria. Total and differential white cell counts, and indirect fluorescent antibody tests specific for B cells and T cells were performed on all sheep. The concentration of various subsets of circulating lymphocytes was then determined in each sheep.
Results There were no significant differences between fleece rot-resistant and -susceptible sheep from either flock in the mean total or differential white cell counts. However, fleece rot-resistant rams in flock 1 did have a significantly higher concentration of circulating SBU-T1⁺ cells than fleece rot-susceptible rams from the same flock. No such difference was noted in the rams from flock 2. While all rams in flock 1 were free of clinical fleece rot, 24 rams in flock 2 (comprising all 17 fleece rot-susceptible and 7 of 15 fleece rot-resistant animals) had clinical signs of the disease. Fleece rot-free rams in this flock (irrespective of their classification as fleece rot-resistant or -susceptible) had significantly higher concentrations of circulating SBU-T1⁺ cells compared with fleece rot-affected animals. They also had significantly higher concentrations of circulating B cells, and total lymphocytes.
Conclusions An examination of peripheral blood lymphocyte subsets in fleece rot-resistant and -susceptible sheep revealed a possible association between resistance to fleece rot and the concentration of circulating SBU-T1⁺ cells.     

The Effect of the Interaction of Forest and Site on Present-day Timber Production Methods

The main site types under forest in Britain are defined by broadsoil types. The interactions between the forest and site inrelation to rotation length, silvicultural system, and standcomposition are briefly considered. Finally the possibilityof site amelioration is mentioned.     

The Application of Fertilizers to Drained Peat 2. Uptake by Vegetation and Residual Distribution in Peat

Analyses of peat cores taken from lysimeters, which had beenused to monitor leaching losses from a drained peat on a raisedbog for three years, showed that much of the applied fertiliser,rock phosphate and potassium chloride, was retained in the uppermost0.3 m of the peat. Undisturbed bog vegetation had accumulated10–13 per cent of the applied P and K and losses to drainagewater amounted to about 10 and 35 per cent respectively. Whenboth nutrients were applied together leaching losses were reduced,vegetation uptake was increased and more was retained in thepeat. Within the fairly wide 95 per cent confidence limits mostof the P and Ca could be accounted for but K showed a deficit.The Ca in the rock phosphate was almost entirely retained inthe peat.