Data on lambing periods from 30 populations of North American mountain sheep are reviewed. Among all populations lambing begins later and duration is shorter at more northern altitudes (p < 0.00006). Correlations are enhanced (p < 0.00003) when latitude is replaced by a phenological index incorporating altitude. Termination of lambing is not correlated with latitude or with phenological index. Two broad patterns are evident. Populations feeding on vegetation of less predictable growth patterns ("desert type") have lengthy lambing seasons; populations feeding on vegetation exhibiting more predictable growth patterns ("alpine type") have shorter lambing seasons, typically two oestrous cycles in length. Definition of "types" by latitude or sheep taxonomy reveals significant differences in lambing periods, but correlations are enhanced when "types" are defined on the basis of habitat.Among taxa, birth weights are correlated with female body weight (rs = 0.87). Birth weights are heavier in extreme environments, seasonal growth patterns are expressed better in the alpine type, and early weight gain is most rapid in the northernmost subspecies. All populations show a strong central tendency with regard to peak lambing (17 May ± 6.8 days). Departures from that tendency respond more to predictability of vegetation than to thermal stress or predation pressure.

Abstract~ Structure of native vertebrate faunas within 12 different forest types were related to features of the natural fire regime. Relations between faunal structure and fire regime followed patterns expected if faunas were adapted to fire regitrw.g Proportions of species breeding early in succession tended to increase with increasing flre size or burn rate (ha~year, p = 0.03); those breeding late in succession tended to decrease (p = 0. 04). As fire size increasea~ proportions of species breeding in cavities decreased (p < O. 01). Proportions of species using downed ttagod to breed increased as the interval between fires increased and downed umod accumulated (p < 0.01). Forestry practices to maintain biodiversity should mimic natural disturbance patterng which differ across forest type£ Implications for management to maintain vertebrate diversity are summarized in terms of the silvicultural system employea~ the size of patches logge~ the rate of timber removal and the appropriate degree of connectivity among unlogged patcheg Las faunas de vertebrados que habitan los bosques y los r6gimenes de incendios naturales en la Columbia Brit~dca: patrones y connotaciones para la conservaci6nResumen: La estructura de la fauna de vertebrados nativos dentro de 12 tipos distintos de bosqueg fue relacionada con caractertsticas del r&gimen de incendios naturaleg Las relaciones entre la estructura de la fauna y el r&gimen de incendios siguieron los patrones esperados para faunas adaptadas al r~gimen de incendioi Las proporci6nes de las especies que se reproducen tempranamente en la sucesi6r~ tendi6 a aumentar con el increraento en el tamaV~o del incendio o tasa de drea quemada (ha/a~o; p = 0.03); aquellas que se reproducen tardlamente en la sucesi6n tendieron a decrecer (p = 0.04). A medlda que el tama~o del incendio aumento, las proporciones de espectes que se crian en cavidades decrece (p < O. 01). Las proporclones de las especies que utilizan madera carla para reproducirse se increment6 en la medlda en que el intervalo entre los incendios aument6 y la madera catda se acumul6 (p < O. 01). Las prdcticas forestales ilevadas a cabo para mantener la biodiversldad deberlan imitar los patrones de las perturbaciones naturaleg las cuales difleren segftn los tipos de bosque£ Las connotaciones para el manejo a efecto de mantener una diversidad de vertebrados se resumen en t~eminos del sistema de silvicultura empleado, el tamafto de los parches taladog la tasa de remoci6n de madera y el grado aproplado de conectivldad entre los parches no talados~

Many species require or use down wood (fine and coarse woody debris) as habitat. Where forestry has been practiced for several rotations large proportions of these species are considered threatened. Key attributes determining the suitability of down wood as habitat are decay stage, tree species, and size, specifically diameter. Both quantity and distribution of suitable down wood influence species' presence and abundance. We present a simple framework describing use of down wood based on broad natural history features, derive predictions from the framework, then test these by review and summary of literature. Our focus is terrestrial vertebrates, particularly in the Pacific Northwest. Species other than vertebrates are addressed to ensure that metrics derived for vertebrates also are appropriate for other organisms. Basic metrics are the same, but appropriate values span a larger range among nonvertebrates. Current evidence suggests that the ''extinction debt'' apparent for nonvertebrates is approaching for vertebrates. Predictions derived from underlying natural history hold when tested. From that basis we derive broad guidelines for forest planning and practice, and suggest how regional target values can be derived. Résumé :Plusieurs espèces nécessitent ou utilisent le bois mort (débris ligneux fins ou grossiers) comme habitat. Là où l'on a pratiqué la foresterie au cours de plusieurs rotations, on considère qu'une large proportion de ces espèces deviennent menacées. Les caractéristiques déterminant l'utilité du bois mort comme habitat regroupent l'état de décomposition, les espèces d'arbres et leurs dimensions, surtout le diamètre. Les quantités ainsi que la distribution de bois mort adéquat influencent la présence des espèces et leur abondance. Les auteurs présentent un cadre de travail simple décrivant l'utilisation du bois mort, basé sur des caractéristiques élargies d'histoire naturelle, déduisent des prédictions à partir d'un tel cadre, et les vérifient finalement par une revue et un résumé de la littérature. On met l'accent sur les vertébrés terrestres, particulière-ment de la région du Pacifique nord-ouest. On considère également d'autres espèces que des vertébrés, afin de s'assurer que les chiffres inférés pour les vertébrés sont également appropriés pour d'autres organismes. Les mesures de base restent les mêmes, mais les valeurs pertinentes couvrent un plus large spectre parmi les non-vertébrés. La preuve actuelle suggère que la « dette d'extinction » apparente pour les non-vertébrés approche celle des vertébrés. Les prédictions dérivées de l'histoire naturelle sous-jacente supportent la mise à l'épreuve. Sur cette base, les auteurs déduisent des directives larges pour la planification et la pratique forestière et suggèrent comment on peut en déduire des valeurs cible à l'échelle régio-nale.

Dead wood is an important habitat feature for lichens in forest ecosystems, but little is known about how many and which lichens are dependent on dead wood. We reviewed substrate use by epiphytic lichens in the combined floras of Fennoscandia and the Pacific Northwest of North America based on literature and herbarium data and analyzed substrate affinity relative to life form, reproductive mode and major phylogenetic group within the floras. A total of 550 (43%) of the 1271 epiphytic species in the combined floras use wood, and 132 species (10%) are obligately associated with dead wood in one or both regions. Obligate and facultative wood-dwelling guilds in the two floras were strongly similar in terms of internal guild structure in each region, but differ somewhat in species composition, while the bark-dwelling guild differs strongly in both. Most obligate dead wood users are sexually reproducing crustose lichens. The largest numbers of species are associated with forest structural features such as logs and snags that have been greatly reduced by forest practices. Conservation of lichens inhabiting wood requires greater attention to crustose lichen species and the development of conservation strategies that look beyond numbers and volumes of dead wood and consider biologically meaningful dead wood structure types.

All, tract: There is a lack of research on the effects of logging on Canadian ampbiblan,~ We compared the abundance of terrestrial salamanders in old-growth forests with that in young and mature post-hartmst stand~ We also measured habitat features of amphibians and contrasted these with old-growth and harvested stands to assess the effects of forest harves£ Quadrat searches demonstrated that clearcut harvesting reduces terrestrial amphibian populations by up to 7096 in coastal old-growth forest~ We suggest that this reduction results from a decrease in availability of moist micaroha~itat& Salamander densities within 10 meters of streams in numaged stands were similar to those near and away from streams in old growth. We recommend that forest managers recognize the needs of terrestrial amphibians and help maintain amphibian populations by preserving cook moist habitat~ This can be accomplished within cuthlocks by (1) maintaining an eve~ distribution of logs and snags as stable, moist microhabitats; (2) retaining some understory as sources of ~ and (3) preserving streamside huffer~ Managers must also ensure some level of landscape connectivity to enable climate-sensitive amphibians to disperse and recolonize marginal habitat~ Relaci6n entre la abundancia de anfibios con reproducci6n terreste y la edad del rodal Resumen: Existe una falta de investigaci6n sobre los efectos de la tala sobre los anfibios canadieme~ En este estudio comparamos la abundancla de las salamandras terrestres en bosques primarios con aquellas de bosques talados j6venes y maduro£ Tambidrg raedimos las caracteristicas del hdhitat de los anfibios y las contrastamos con bosques primarios y rodales bajo explotaci6n, para evaluar los efectos de la tala Muestreos basados en la busqueda de salamandras en una serie de cuadrantes dispuestos al azar dentro de un drea timitada~ demostraron que la tala redujo las poblaciones de anfibios basra en un 70% en bosques costeros primario~ Sugerimos que esta reducci6n es el resultado de un decrecimiento en la disponibilidad de microhdbitats htimedo~ Las densidades de salamandras dentro de los I0 mque bordean a los arroyos en rodales bajo manejo, fueron similares a aquellas en dreas cercanas y lejanas a los arroyos en bosques primario& Recomendamos que los encargados de administrar bosques, reconozcan la necesidad de los anfibios terrestres y ayuden a mantener laspoblaciones de anfibiospreservando hdbitatsfrescosy htimedo~ Esto puede lograrse dentro de los bloques talados mediante 1. el raantenimiento de una distribuci6n par~a de troncos cortados y tocones como micro-hdbitats htimedos estables; 2. dejando parte del sotobosque como fuente de sombra y 3. preservando dreas a los costados de los arroyos que sirrah para amortiguar los efectos de la tala~ Tambidm se debe asegurar un cierto nivel de conectividad dentro del paisaje, que permita a los anfibios sensibles a los cambios climdticos, dispersarse y recolonizar hdbitats ma~inale~

Many regions confront potentially competing goals: sustaining biological diversity and extracting wood products from forests rich in biological diversity. Forests of the Pacific Northwest are particularly rich in vertebrates. Because little is known of many species, management tactics to sustain vertebrate richness must employ interim surrogates that credibly reflect responses of groups of vertebrates. These tactics should focus on elements of the forest, commonly altered by forest practices, to which groups of species are closely linked. We identify five such elements for forests of the Pacific Northwest: dead and dying trees, downed wood, shrubs, hardwoods (broadleaved, deciduoustrees), and riparian areas. Most forest-dwelling vertebrates in the Pacific Northwest, including those designated "at risk", require one or more of these forest elements. Late-successional forests represent particular mixes of these elements. Each element can be altered in ways that benefit or harm specific groups of species. Any management decision, including taking no action at all, favours some species while disadvantaging others. We report the proportions of the vertebrate fauna associated with the five forest elements, plus early- and late-successional stages for a range of forest types. The nature of relationships with each forest element is quantified by biologically appropriate measurements (e.g., decay state, tree species, snag density, and tree size for cavity sites). Impacts of current practices are summarized and tactics appropriate for maintaining vertebrates are described. Responses of organisms other than vertebrates are noted. Key words: forest practices, Pacific Northwest, vertebrate richness.

Foraging behaviour of Stone's sheep (Ovis dalli stonei) was compared between different times of the year and between burned and unburned ranges. Seasonal habitat selection resulted in the sheep feeding on the ranges which provided the highest quality available forage. In winter, snow severely restricted the area that provided available forage. Sheep fed primarily on grasses, although forbs and browse were also important foods in the spring and summer. Plant species selected by the sheep in summer were not higher in protein or lower in acid detergent fiber than avoided species, but rather lacked the physical and chemical deterrents present in avoided plants. Intake rate (estimated from biting rate of ewes and foraging time) appeared to be independent of herbage quantity on spring ranges.

Thirteen techniques for estimating forest overstory cover or mean crown completeness were tested for differences in angle of view of the technique and interaction with mean crown completeness or height to base of live crown. With increasing angle of view from common locations, mean estimates of mean crown completeness increased and the standard deviation decreased. For techniques with angles of view >30° there was interaction among techniques with changing overstory cover. As mean crown completeness increased, the differences between wide- and narrow-angled techniques decreased and converged to 0 at a rate dependent on the angle of view. For most techniques the estimate of mean crown completeness increased with height to base of live crown. The more narrow the angle of view the greater was the effect of increasing height to base of live crown. Differences among techniques were those expected from basic trigonometry; they occur because wider angles of view are less likely to encounter only space without canopy. Attempts to develop relations between overstory cover and other factors (e.g., snow interception, understory growth) should use angles of view appropriate to the factor being studied.