Effects of Fencing and Ground Preparation on Natural Regeneration of Native Pinewood over 12 years in Glen Tanar, Aberdeenshire

An enumeration was carried out in 1989 to assess the effectsof fencing and ground treatment 11 years previously on survivaland growth of naturally disseminated Scots pine seedlings inthe native pinewood at Glen Tanar, Aberdeenshire. Results showeda significant difference between unfenced and fenced plots onpine seedling density and height in 1989. Initial effects ofseedbed treatment on Scots pine seedling density, 2 years afterthe experiment began had largely disappeared by 1989. If removalof ground cover is used to enhance pine seed germination, theexposed seedlings may need to be protected from browsing byfencing. Received 19 March 1990.     

Hydrochemical Fluxes and their Effects on Stream Acidity in Two Forested Catchments in Central Scotland

The hydrochemical fluxes and budgets have been determined fortwo forested catchments, including inputs, tree throughfalland stemflow, soil water throughflow and output streams. Themajor vegetational induced differences are the enrichment ofsodium, chloride, sulphate and particularly hydrogen by Sitkaspruce compared to Norway spruce. These increased concentrationsare primarily due to vegetation interception along with crownleaching, both of which contribute to sulphate enhancement.Soil throughflow and consequent stream chemistries reflect thesespecies effects with additional enrichment both due to geologicalweathering of base cations as well as possible desorption ormineralization processes. Norway spruce vegetation and the associatedpodzolic soils show no net stream acidification (pH 4.61) ofinputs (pH 4.65), whereas Sitka spruce on gleyed soils showconsiderable stream acidification (pH 4.02) compared with similarinputs (pH 4.50). Both streams have similar sulphate concentrations,but this important mobile anion is associated primarily withhydrogen in the Sitka spruce dominated Kelty catchment whereasat Chon it is associated with base cations as well as hydrogen.     

Effects of Refertilization on Growth and Nutrition of Lodgepole Pine (Pinus contorta Dougl.) Planted on a Minerotrophic Peatland in Central Newfoundland, Canada

A plantation of lodgepole pine (Pinus contorta Dougl.), whichwas established in 1973 on a ditched minerotrophic fen at plantingspacings of 1.2 m, 1.8 m, and 2.4 m, was refertilized in 1985with control, P, PK and NPK treatments consisting of 60 kg ha^–1phosphorus, 100 kg ha^–1 potassium and 200 kg ha^–1nitrogen. Although each seedling had been spot-fertilized in1973 with a mixture of 71 g urea, 99 g ground rock phosphateand 41 g potassium sulphate, height and needle nutrient assessmentsof the plantation in 1984 indicated poor growth, low concentrationsof needle nitrogen (1.26 per cent) and possible deficiency levelsof needle phosphorus (0.10 per cent) and potassium (0.36 percent). Between 1985 and 1991, height and diameter growth increasedsignificantly in all refertilization treatments. Growth responsewas greatest in the PK treatment and least in the P treatment.Needle weights, determined from 1987 to 1991, did not responduniformly to any of the refertilization treatments. Needle concentrationsof phosphorus increased to levels between 0.20 per cent and0.23 per cent following refertilization with P, PK, and NPK,but by 1988 had decreased to about 0.14 per cent. Needle concentrationsof potassium also increased sharply to 0.60 per cent in 1985following refertilization with PK and NPK, but by 1988 had decreasedto levels between 0.35 per cent and 0.45 per cent. Similarly,needle nitrogen concentrations increased to 1.84 per cent in1985 following refertilization with NPK, then decreased to levelsbetween 1.20 per cent and 1.33 per cent in 1986 and remainedat those levels each year thereafter. Although needle nutrientlevels fell sharply following an initial peak after refertilization,height and diameter growth did not decrease significantly, especiallyin the PK treatment, suggesting that nutrient levels remainedadequate for optimum growth.     

The Effect of Landfill Leachate Spraying on Foliar Nutrient Concentrations and Leaf Transpiration in a Northern Hardwood Forest, Canada

The effect of municipal solid waste (MSW) leachate spray irrigationon a mature northern hardwood forest was investigated. Canopyfoliar samples and stem increment cores were collected fromtwo indicative species, sugar maple (Acer saccharum Marsh.)and American beech (Fagus grandifolia Ehrh.), within each ofa heavily sprayed, lightly sprayed and control area. Foliarconcentrations of N and P were significantly higher in bothmaple and beech foliage within the sprayed areas when comparedto an unsprayed area (control). Levels of Mg and K were markedlyhigher in maple but not beech foliar samples within the heavilysprayed areas when compared to foliage sampled within the unsprayedcontrol. While no significant trends were observed within themaple foliage, both Fe and B levels increased significantlyin beech foliar samples obtained from within the heavily sprayedarea in comparison to foliage samples from the control. Directporometric measurements of the transpiration rate and diffusive(stomatal) resistance of canopy and understory plant leavesrevealed a significant increase in diffusive resistance anda decline in transpiration rate with leachate spraying. Afterfour years of spraying a significant effect of leachate applicationon radial stem growth of both maple and beech trees has notbeen observed.     

The Interaction of Green Spruce Aphid and Fertilizer Applications on the Growth of Sitka Spruce

In an 11-year-old stand of Sitka spruce (Picea sitchensis [Bong.]Carr.) application of nitrogen fertilizers, at a rate of 10kgN ha^–1 month^–1, increased mean diameter incrementby 12 per cent, while the further addition of phosphorus, at5 kg ha^–1 month^–1, resulted in a 23 per cent increase.An attack by the green spruce aphid (Elatobium albietinum Walker)occurred during the period of fertilizer addition. The mostseverely affected trees showed a reduction in diameter growthof 50 to 56 per cent but the severity of the attack betweentrees was unrelated to the treatments applied. However, fertilizerapplication did hasten the recovery of diameter growth afterdefoliation.     

Colour Dilution Alopecia in Doberman Pinschers with Blue or Fawn Coat Colours: A Study on the Incidence and Histopathology of this Disorder

Abstract— A population of 57 blue or fawn Doberman Pinschers was studied to determine the incidence of colour dilution alopecia in this breed. Forty two dogs had hair loss, typical of colour dilution alopecia. The diagnosis was confirmed in 11 dogs by skin biopsy and in 6 dogs by light microscopic examination of plucked hairs. Key diagnostic features included large macromelanosomes in the hair shafts, free clumps of melanin in the lumens of hair follicles, and numerous perifollicular melanophages. An hypothesis on the pathogenesis of colour dilution alopecia is proposed. Résumé— Une population de 57 Pinschers à robe bleue ou feu a étéétudiée pour déterminer la fréquence de l'alopécie par dilution de couleur dans cette race. 42 chiens ont présenté une perte de poils caractéristique de l'alopécie par dilution de couleur. Le diagnostic a été confirmé chez 11 chiens par biopsie cutanée et chez 6 chiens par l'examen au microscope optique des poils épilés. Les caractéristiques diagnostiques comprennent la présence de grands macromélanosomes dans les racines des poils, de manchons libres de mélanine dans la lumière des follicules pileux et de nombreux mélanophages périfolliculaires. Une hyhpothèse sur la pathogénie de l'alopécie par dilution de couleur est proposée. Zusammenfassung— Untersucht wurden 57 blaue und rehfarbene Dobermänner, um das Vorkommen der Farbmutanten-Alopezie bei dieser Rasse feststellen zu können. 42 dieser Hunde zeigten den für diese Erkrankung typischen Haarausfall. Bei 11 Patienten wurde die Diagnose durch Hautbiopsie und bei 6 durch lichtmikroskopische Untersuchung von ausgezupften Haaren gesichert. Die charakteristichen Bilder waren Makromelanosome in den Haarschäften, freies zusammengeballtes Melanin im Lumen der Haarfollikel und zahlreiche perifollikuläre Melanophagen. Eine Hypothese für die Pathogenese dieser Erkrankung wird aufgestellt. Resumen Se estudió una población de 57 perros de raza Doberman y color gris o azul para determinar la incidencia de la alopecia por dilución de color en esta raza. 42 perros presentaban pérdidas de pelo típicas de la alopecia por dilución de color. En 11 perros el diagnóstico se confirmó mediante biopsia y en 6 mediante examen microscópico del pelo. Las características diagnósticas de este proceso consistían en la presencia de macromelanosomas en las vainas de los pelos, y en la presencia de acúmulos de melanina libre en el interior de los folículos pilosos y de melanófagos perifoliculares. Se propone una hipótesis sobre la patogenia de esta enfermedad.     

Endoscopy (fibreoptic) of the oesophagus and stomach in the dog with persistent regurgitation or vomiting

A flexible gastrointestinal panendoscope was used to examine 90 dogs; 29 for oesophageal and 61 for gastric investigation. Twenty-two of the oesophageal cases had changes associated with foreign body obstruction. The commonest feature was simple mucosal damage. Small numbers of strictures (5), diverticula (1) and perforations (4) were identified. The remainder of the cases were vascular rings (5) and leiomyomata (1). The 61 gastroscopies could be subdivided into the following groups: 1, no abnormalities (14); 2, chronic gastritis (16); 3, neoplasia (26); 4, others (5). Further, gastric carcinoma accounted for 36 per cent of all gastroscopic examinations. Oesophageal abnormalities were found in 13 per cent of those cases investigated for, and found to have, gastric lesions, where reflux oesophagitis (5) was the commonest lesion.     

State Infrastructure and the Geography of Employment

ABSTRACT The effects of state public capital investment on economic growth is an important question that has been the focus of a recent substantial research effort. But the majority of this research has ignored these investments’influence on the intra-state pattern of economic activity. Yet if external agglomeration economies are important determinants of growth, then investments may indirectly affect growth by fostering or discouraging agglomeration. This paper discusses the effect of state infrastructure investments on the distribution of employment within states and the implications of these spatial effects for aggregate state employment growth. Preliminary empirical results suggest that state infrastructure investments tend to redistribute growth from areas of dense employment to other parts of the state. This redistribution may diminish agglomeration benefits offered by cities, which has the potential to reduce state growth. The paper concludes with a discussion of implications of the work for research and policy.     

Public vs. Private Garbage Disposal: The Economics of Solid Waste Flow Controls

ABSTRACT The welfare effects of public versus private waste disposal with and without flow controls are analyzed. The pricing of private waste disposal services is modeled as being bounded above by the public entity's average disposal cost, but constrained by potential entry of private competitors. It is found that once a publicly owned disposal facility has been built, waste generators are almost always better off if their local government has flow control authority. This results from the necessity of covering the fixed costs of the public facility once it has been built, in conjunction with the expected pricing behavior of private firms.