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Browse subject: old-growth forests
Number of records: 45

Broad-Scale Classification and Mapping of Tree Size and Density Attributes in Productive Old-Growth Forests in Southeast Alaska's Tongass National Forest
About this Resource: The forest classification and mapping system currently used in managing the Tongass National Forest (NF) is based largely on an economic forest measure, net board foot volume per acre. Although useful for timber economic modeling, this forest measure poorly differentiates old-growth forest types in a way that is meaningful to ecological and social concerns. In 2005, we published an article presenting a proposed tree size and tree density mapping model for the Tongass NF. We claimed the model would provide better information on the structural patterns in old-growth forests than did the current mapping models based on net board foot volume per acre. We also stated that further testing of our proposed model is required before it can be fully integrated into forest management plans and landscape analysis. In this article, we used independent field data to evaluate our proposed tree size and density model and better define its accuracy. Results showed differences among mapping classes similar to differences observed in the development stages of the model. Results also showed mapping accuracy estimates between 60 and 80%. We used the model in a forest management application by comparing the representation of old-growth forest types within a landscape to the representation within a management-defined subset of that landscape.

Carbon storage in coarse and fine fractions of Pacific Northwest old-growth forest soils
About this Resource: Many assessments of soil C have been restricted to the <2-mm fraction, but C has recently been identified in >2-mm fractions of forest mineral soils. Our objective was to determine the importance of the >2-mm fraction to whole-soil C pools in Pacific Northwest old-growth coniferous forests. Seventy-nine pedons in 18 western Washington and Oregon forests were sampled to a depth of 100 cm. The <2-mm fraction was separated from the >2-mm fraction by air-drying, physically crushing soil, and sieving; C was determined by Leco combustion. The >2-mm fraction contained up to 46% of the whole-soil C and averaged 23% for the seven forests that had C in that fraction. Following treatment with sodium hexametaphosphate to disaggregate soil material, up to 20% of whole-soil C remained in the >2-mm fraction. Thus, the >2-mm fraction C appears to be in stable and unstable aggregates, as well as concretions. The whole-soil C in the surface 100 cm of mineral soil ranged from 30 to 400 Mg C ha(-1). Multiple regression analysis indicated this C pool was positively related to available water capacity, annual precipitation, and coarse woody debris (r2 = 0.63 to 0.66, n = 18 forests). Similar results were obtained with only the <2-mm soil C, which is the basis of previous regional evaluations. This suggests consideration of the >2-mm fraction does not alter our understanding of the importance of climate and soil texture as controls of soil C pools, but it does affect the quantification of soil C pools in many old-growth forests in the Pacific Northwest.

Using occupancy estimation to assess the effectiveness of a regional multiple-species conservation plan: Bats in the Pacific Northwest
About this Resource: Regional conservation plans are increasingly used to plan for and protect biodiversity at large spatial scales however the means of quantitatively evaluating their effectiveness are rarely specified. Multiple-species approaches, particular those which employ site-occupancy estimation, have been proposed as robust and efficient alternatives for assessing the status of wildlife populations over large spatial scales, but implemented examples are few. I used bats as a model to evaluate design considerations for the use of occupancy estimation to assess population status and habitat associations for eight species of bats covered under a regional conservation plan. Bats were one of the groups expected to benefit from a system of reserves for species associated with late-successional/old-growth (LSOG) habitat designated under the Northwest Forest Plan (NWFP). This study produced the first estimates for probabilities of occupancy and detection for bats at a regional scale. Overall probabilities of occupancy ranged from 0.586 to 0.783 and probabilities of detection ranged from 0.239 to 0.532 among the eight species modeled. Although point estimates of occupancy suggested association with NWFP habitat categories for some species, estimate precision was low. Models that assumed constant occupancy with respect to reserve- and LSOG-status were supported for most species. I used model-averaged estimates of occupancy and detection for each species to estimate survey effort necessary to meet precision targets. Occupancy estimation was best suited to species with the highest detection probabilities. Species that are rare or difficult to detect will require enhancement in survey methods or more intensive survey effort to produce meaningful estimates. Optimizing monitoring efforts to address multiple species requires tradeoffs among survey methods, levels of effort, and acceptable levels of precision.

Presettlement and modern disturbance regimes in coast redwood forests: Implications for the conservation of old-growth stands
About this Resource: Coast redwood (Sequoia sempervirens), a western North American conifer of ancient lineage, has a paradoxical combination of late-successional characteristics and strong adaptations to disturbance. Despite its shade tolerance and heavy dominance of the canopy on many sites, redwood saplings are uncommon in upland old-growth stands. Information needed to ensure the conservation of old-growth redwood forests has been limited. In this review paper, we integrate evidence on redwood biology with data on the historic and modern disturbance regimes to help clarify the degree to which key attributes of redwood forests may have been dependent upon periodic disturbance. Available evidence suggests that episodes of fire, flooding, and slope failure prior to European settlement were frequent but predominantly of low to moderate severity and extent, resulting in broadly uneven-aged forests. The majority of fires prior to European settlement were apparently of human origin. Frequency and severity of the major disturbance agents have been radically changed in modern times. Fires have been largely excluded, and flooding has been altered in ways that have often been detrimental to old-growth redwoods on alluvial terraces. However, because of the apparent anthropogenic origin of most presettlement fires, the long-term evolutionary role of fire for coast redwood is ecologically ambiguous. With fire exclusion, redwood possibly could be displaced to some extent on upland sites by increasing abundance of fire-sensitive competitors. Alternatively, redwood may be able to maintain dominance by vegetative sprouting and new seedling establishment on root-wad mounds, fallen logs, and on soil exposed by slope failure. Future research priorities are suggested that will help resolve some of the current ambiguities.

Nitrous oxide fluxes and nitrogen cycling along a pasture chronosequence in Central Amazonia, Brazil
About this Resource: We studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarem, Para, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N2O we measured 27 soil chemical, soil microbiological and soil physical variables. Soil N2O fluxes were higher in the wet season than in the dry season. Fluxes of N2O from forest soils always exceeded fluxes from pasture soils and showed no consistent trend with pasture age. At our forest sites, nitrate was the dominant form of inorganic N both during wet and dry season. At our pasture sites nitrate generally dominated the inorganic N pools during the wet season and ammonium dominated during the dry season. Net mineralization and nitrification rates displayed large variations. During the dry season net immobilization of N was observed in some pastures. Compared to forest sites, young pasture sites (<or= 2 years) had low microbial biomass N and protease activities. Protease activity and microbial biomass N peaked in pastures of intermediate age (4 to 8 years) followed by consistently lower values in older pasture (10 to 60 years). The C/N ratio of litter was low at the forest sites (~25) and rapidly increased with pasture age reaching values of 60-70 at pastures of 15 years and older. Nitrous oxide emissions at our sites were controlled by C and N availability and soil aeration. Fluxes of N2O were negatively correlated to leaf litter C/N ratio, NH4+-N and the ratio of NO3--N to the sum of NO3--N+ NH4+-N (indicators of N availability), and methane fluxes and bulk density (indicators of soil aeration status) during the wet season. During the dry season fluxes of N2O were positively correlated to microbial biomass N, β-glucosidase activity, total inorganic N stocks and NH4+-N. In our study region, pastures of all age emitted less N2O than old-growth forests, because of a progressive decline in N availability with pasture age combined with strongly anaerobic conditions in some pastures during the wet season.

First direct landscape-scale measurement of tropical rain forest Leaf Area Index, a key driver of global primary productivity
About this Resource: Leaf Area Index (leaf area per unit ground area, LAI) is a key driver of forest productivity but has never previously been measured directly at the landscape scale in tropical rain forest (TRF). We used a modular tower and stratified random sampling to harvest all foliage from forest floor to canopy top in 55 vertical transects (4.6 m²) across 500 ha of old growth in Costa Rica. Landscape LAI was 6.00 ± 0.32 SEM. Trees, palms and lianas accounted for 89% of the total, and trees and lianas were 95% of the upper canopy. All vertical transects were organized into quantitatively defined strata, partially resolving the long-standing controversy over canopy stratification in TRF. Total LAI was strongly correlated with forest height up to 21 m, while the number of canopy strata increased with forest height across the full height range. These data are a benchmark for understanding the structure and functional composition of TRF canopies at landscape scales, and also provide insights for improving ecosystem models and remote sensing validation.

Overstory and understory development in thinned and underplanted Oregon Coast Range Douglas-fir stands
About this Resource: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests managed for timber in western Oregon frequently lack structure and diversity associated with old-growth forests. We examined thinning effects on overstory and understory development for 8 years after treatment. Three 30- to 33-year-old Oregon Coast Range plantations were partitioned into four overstory treatments: unthinned (approximately 550 trees/ha) and lightly (approximately 250 trees/ha), moderately (approximately 150 trees/ha), and heavily (approximately 75 trees/ha) thinned. Within each overstory treatment, two understory treatments were established: underplanted with Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.) or not underplanted. Thinning increased overstory stem growth, crown expansion, and retained crown length. Thinned overstory canopies began to close rapidly the third year after thinning, decreasing % skylight by approximately 2%/year, whereas % skylight in unthinned stands increased slightly. All seedlings planted in unthinned stands died, whereas eighth year survival in thinned stands averaged 88%. Natural regeneration densities and distributions were highly variable. Understory shrub cover was reduced by harvesting disturbance but recovered by the fifth year. Thinning increased understory plant species diversity, and no shrub species were lost. Thinning to low densities and underplanting has the potential to accelerate development of multilayered stands characteristic of old-growth Douglas-fir forests.

Habitat Selection by American Martens in Coastal California
About this Resource: We investigated habitat selection using single- and mixed-scale modeling at 2 spatial scales, stand and home range, by the only known population of American martens (Martes americana) remaining in the historical range of the Humboldt subspecies (M. a. humboldtensis) in California, USA. During 2000 and 2001, we sampled a 12 x 14 grid with 2-km spacing, using 2 sooted track plates at each grid point. We detected martens at 26 of the 159 grid points. We used resource selection probability functions and an information-theoretic method to model habitat at detection locations. At the stand scale, martens selected conifer-dominated stands with dense, spatially extensive shrub cover (average = 74% cover, SE = 4) in the oldest developmental stage. At the home-range scale, martens selected the largest available patches ( average = 181 ha, SE = 14) of old-growth, old-growth and late-mature, or serpentine habitat. Mixed-scale models revealed that habitat characteristics from both scales best explained marten occurrence compared to one scale alone. Dense, spatially extensive shrub cover is a key habitat element for martens in coastal forests. Dense shrubs provide refuge from predators, cover for prey, and may also deter larger-bodied competitors. Managers can increase the likelihood of marten population persistence and encourage expansion in coastal forests by maintaining and restoring late-mature and old-growth, conifer-dominated forests with dense shrub cover in large, contiguous patches.

Old-growth forest structure in Eastern Oregon and Washington
About this Resource: Old-growth forest structure is an important issue in managing for forest health and productivity in eastern Oregon and Washington, USA. Old-growth forest structure is estimated to be as little as 3% of presettlement levels; what remains is in isolated patches and is at risk of loss from less frequent but more severe fires. Low-elevation ponderosa pine (Pinus ponderosa) and Douglas fir (Pseudotsuga menziesii) stands are more densely stocked with increased fuel, and often represent compositional shifts to more lodgepole pine (Pinus contorta) and grand fir (Abies grandis). The changes are attributed to changes in natural disturbance regimes as a result of management of fire, grazing, timber harvest, wildlife, insects, and disease. Treatments that can accelerate development of old-growth forest structure include thinning to accelerate growth on residual stems, returning fire to fire-dependent ecosystems, and maintaining large trees and snags. These methods have risks: prescribed fire may not mimic frequency and severity of historical fire, thinning may activate dormant stem decay, increased connectivity may increase susceptibility to stand-replacement fire, insects, and pathogens. Models for multiple species and interactions of treatments, insects, and disease are not available.

Effects of timber harvest on Cimicifuga elata, a rare plant of western forests
About this Resource: Cimicifuga elata (tall bugbane) is a Species of Concern with the U.S. Fish and Wildlife Service and it is considered by Natural Heritage programs in Oregon and Washington to be endangered. Since the species occurs in forests, its conservation could conflict with other forest uses such as timber harvest. It has been postulated that the species is dependent on old-growth coniferous forests. The objectives of this study were to compare populations of this species among sites with differing forest-management histories. In contrast to previous reports, we found that C. elata in uncut old-growth forest was smaller and less reproductive than in clearcuts, probably because plants responded well to additional light in cut-over areas. Plants in areas with other management histories, such as second growth and thinned stands (both >70 years old), were intermediate in size. Population structure also differed among management types. Herbivory by deer and elk was more frequent in clear cuts andedges than in unmanaged old-growth forests. No populations were known at the time of this study from second growth forests of moderate age (20-30 years), and it is possible that competing vegetation excludes C. elata from clearcuts after a few years. Management actions that retain hardwoods, thin stands, or create gaps may improve at least short-term conditions for this species

Occurrence and abundance of fungus–dwelling beetles (Ciidae) in boreal forests and clearcuts: habitat associations at two spatial scales
About this Resource: Insect material (> 30,000 individuals) reared from the fruiting bodies of wood–decaying Trametes fungi was compared between old–growth boreal forests and adjacent clearcuts in Finland. Sulcacis affinis and Cis hispidus occurred more frequently and were, on average, more abundant in the clearcuts. Interestingly, Octotemnus glabriculus and Cis boleti had a slightly higher frequency of occurrence in the forests, despite lower resource availability. The former also showed a higher average abundance. On average, the cluster size of Trametes fruiting bodies occurring on woody debris was higher in the clearcuts than in the forests and had a positive effect on species occurrence and abundance in these clusters. The independent effect of the macrohabitat (forest or clearcut) underscores the importance of the macrohabitat where specific resources occur, and this may override the positive effects of resource availability.

Isozyme markers associated with O3 tolerance indicate shift in genetic structure of ponderosa and Jeffrey pine in Sequoia National Park, California
About this Resource: Effects of canopy ozone (O3) exposure and signatures of genetic structure using isozyme markers associated with O3 tolerance were analyzed in 20-, 80-, and >200-yr-old ponderosa (Pinus ponderosa Dougl. ex Laws.) and Jeffrey pine (Pinus jeffreyi Grev. & Balf.) in Sequoia National Park, California. For both species, the number of alleles and genotypes per loci was higher in parental trees relative to saplings. In ponderosa pine, the heterozygosity value increased, and the fixation index indicated reduction of homozygosity with increasing tree age class. The opposite tendencies were observed for Jeffrey pine. Utilizing canopy attributes known to be responsive to O3 exposure, ponderosa pine was more symptomatic than Jeffrey pine, and saplings were more symptomatic than old growth trees. We suggest that these trends are related to differing sensitivity of the two species to O3 exposure, and to higher O3 exposures and drought stress that younger trees may have experienced during germination and establishment. Genetic variation in isozyme markers associated with ozone tolerance differed between parental trees and their progeny in two closely related species of yellow pine.

Red-tree vole habitat suitability modeling: Implications for conservation and management
About this Resource: In the Pacific Northwest, USA, red-tree voles (Arborimus longicaudus) are of conservation and management interest owing to their apparent association with late-seral forests and the relatively small extent of such forests, largely a function of timber harvest, fire, and conversion of forests to non-forest uses during the past century. We created and evaluated a series of red-tree vole habitat association models, and applied the best model to evaluate tree vole habitat quality within and outside of reserves throughout most of their range in Oregon and northern California. We modeled presence and absence of tree vole nests across a gradient of biotic, abiotic, and spatial features; and within and outside of reserves. The best model included spatial coordinates, percent slope, basal area of trees with diameter at breast height (dbh) between 45 and 90cm, maximum tree dbh, and standard deviation of conifer dbh. Plots with tree vole nests contained many late-seral/old-growth forest attributes such as large diameter, older, and variably sized trees. Evaluation of the best model, including rigorous cross-validation, showed the model to be statistically robust and to have very good/excellent predictive ability. Reserves had significantly higher mean habitat quality than non-reserved lands, and reserves had much more high quality habitat than non-reserves.

Structure of an old-growth stand (Reserve of Lom, Republic of Bosnia Herzegovina) and two over-mature forest stands from the Italian eastern Alps (Ludrin, TN, and Val Navarza, UD)
About this Resource: The Republic of Bosnia Herzegovina is a country relatively rich (2000 ha) of primeval and old-growth forests that are very rare in central and southern Europe. One of the best Bosnian old-growth is located in the forest of Lom where a Forest reserve of 278 ha was established in 1956. Inside this reserve, 1 ha long-term intensive monitoring plot was established in 2005 to investigate the origin, spatio-temporal development and disturbance history of the stand. Structural characteristics of the stand were than compared with other Bosnian old-growth and with two well-preserved Italian forests belonging to the same forest type. The permanent plot is very rich in living biomass (1158 m3 ha-1) and in coarse woody debris (383 m3 ha-1 approximately 33% of living trees). The oldest trees are more than 450 years old. The stand has developed without large-scale disturbances and, according to data coming from other Bosnian old-growth, appears to be highly stable. The main differences between a true old-growth (Lom) and the previously managed forests of Ludrin and Navarza are the quality and the quantity of coarse woody debris, the size of the largest trees and the age of the oldest trees. The importance of Forest Reserves as a reference for managed forest and as a site for long-term ecological research is discussed.

The Forest Sector: Important Innovations
About this Resource: Unlike other resources such as petroleum, coal, and copper, forests are renewable. Yet, in many respects forests historically have been treated as a nonrenewable resource in that forest stocks were depleted or "mined" and loggers moved on to exploit other "deposits." The lands were often put to other uses, typically agricultural, or allowed to regenerate naturally. This paper looks at technical change in forest extraction, i.e., logging under a number of different conditions. It finds that, on average, labor productivity has been increasing in recent decades. However, total factor productivity in the US has declined in recent years. In addition, the study examines the tree-growing potential of plantation forestry. It finds that there is underway a substantial shift away from the harvesting of old-growth forests and toward intensive forest plantations. Plantations allow for high productivity in tree growing and are being used to offset decreased wood availability due to the inaccessibility and high costs of many old- and second-growth forests. The decreased accessibility reflects not only the impacts of past logging but, perhaps more importantly, the increase in forests in protected area set asides. Additionally, natural forests face increasingly stringent regulations on logging and forest management activities. High-yield intensively managed forests, on well located, high productivity sites, offer the potential of obtaining high yields while using relatively small land areas by allowing the near full output potential of practices including species selection, fertilization and pest control. Finally, tree planting creates the opportunity to apply genetic improvements to the tree stock thereby further increasing growth productivity and allowing for control of tree characteristics.

Sensitivity of Amazon rainforest to drought: results from forest inventories
About this Resource: A recent study based on inventory data from the RAINFOR network, published in the journal Science, reported a relevant effect of an anomalous dry year (2005) on biomass accumulation and mortality in Amazon old-growth forests. Results were obtained by comparing inventory data taken before and after the dry year and point to biomass losses in consequence of drought. These losses were driven by large mortality increases at some plots and by small but diffuse declines in growth. If upscaled to the area affected by drought, the release of carbon (1.21 PgC) would be much larger than that resulting from deforestation in the area (0.3÷0.8 PgC) and would offset the carbon gained in the recent past (0.5 PgC). As the frequency of extreme dry years is expected to increase in future climate scenarios, regional carbon balances may be strongly impacted with a positive feedback on climate change. The main results of the paper are briefly presented and commented.

The importance of canopy structure in controlling the interception loss of rainfall: examples from a young and an old-growth Douglas-fir forest
About this Resource: The canopy water storage capacity (S), direct throughfall fraction (p), the ratio of evaporation to rainfall intensity (E/R) and interception loss (I(n)), of a Douglas-fir forest are influenced by short (seasonal) and long-term (decades to centuries) changes in the forest canopy. Gross precipitation (P(G)) and net precipitation (P(n)) were measured in a young (25-year-old) Douglas-fir forest and the results compared with measurements previously made in a nearby old-growth (>450-year-old) Douglas-fir forest [Link, T.E., Unsworth, M.H., Marks, D., 2004. The dynamics of rainfall interception by a seasonal temperate rainforest. Agric. Forest Meteorol. 124, 171-191.]. Canopy rainfall variables were estimated using a regression-based method that estimates S, p and E/R for individual storms using the relationship between P(G) and P(n). The individual storm estimates of S, p and E/R for the young forest were applied to a rainfall interception model (Gash model [Gash, J.H.C., 1979. An analytical model of rainfall interception by forest. Q. J. R. Meteorol. Soc. 105, 43-55.]) to determine the effect of seasonal changes in canopy hydrologic variables have on estimates of I(n) (young forest only). The Gash model was previously applied to the old-growth forest [Link, T.E., Unsworth, M.H., Marks, D., 2004. The dynamics of rainfall interception by a seasonal temperate rainforest. Agric. Forest Meteorol. 124, 171-191.]. The young forest had significantly different S (1.40 mm +/- 0.27) and p (0.12 +/- 0.07) relative to the old-growth forest (S = 3.32 +/- 0.35; p = 0.42 +/- 0.07). Seasonal variation in canopy structure, such as deciduous leaf senescence and coniferous needle drop, were correlated with decreases in S. The differences in S and p between the two forests resulted in an I(n) that was only slightly larger in the old-growth forest because the E/R for the two forests were similar (young = 0.18 +/- 0.06; old-growth = 0.17 +/- 0.08). E/R in the young and old-growth forests may have been similar because developmental changes associated with old-growth forest may alter the external resistance (r(a)) and the effective area for evaporation. The Gash model successfully predicted I(n) for the young forest on a seasonal basis (3.29% error), but experienced larger errors (range = -91 to 36% error) for individual storms. The seasonal error and the error for individual storms improved when seasonal variations in canopy characteristics were incorporated in the model (seasonal error = 2.37%; individual storm error range = -12.0 to 21.7%). Therefore, short-term (seasonal) changes in phenology and long-term (decades to centuries) horizontal and vertical development of the forest canopy influence S, p, I(n) and E/R of Douglas-fir forests.

Effects of multiple environmental factors on CO2 emission and CH4 uptake from old-growth forest soils
About this Resource: To assess contribution of multiple environmental factors to actual carbon exchanges between the atmosphere and forest soils, four old-growth forests referred to as boreal coniferous forest, temperate needle-broadleaved mixed forest, subtropical evergreen broadleaved forest and tropical seasonal rain forest were selected along the eastern China. In each old-growth forest, soil CO2 and CH4 fluxes were measured for three years using the static chamber and gas chromatography technique. Soil temperature and moisture at the 10 cm depth were measured simultaneously with the greenhouse gas measurements. Inorganic N (NH4+-N and NO3--N) in the 0–10 cm was determined monthly. From north to south, annual mean CO2 flux ranged from 18.09±0.22 to 35.40±2.24 Mg CO2 ha−1 yr−1 and annual mean CH4 flux ranged from -0.04±0.11 to -5.15±0.96 kg CH4 ha−1 yr−1. Soil CO2 fluxes in the old-growth forests were mainly driven by soil temperature, followed by soil moisture and NO3--N. Based on the gradient theory of exchange of time and space, increase in air temperature in the future would promote soil CO2 emission in the old-growth forests. The responses of soil CH4 uptake to warming were dependent upon the critical temperature in forest. In addition, the NO3--N promotion to CO2 emission could partially attribute to the compound effects of high nitrate stimulation on soil microbe activities and increased decomposability of organic materials. The mechanism of NH4+ inhibition to CH4 uptake included both a competitive inhibition of CH4 mono-oxygenase enzyme and a toxic inhibition by hydroxylamine or nitrite produced via NH4+ oxidation. Overall, increasing in precipitation and nitrogen deposition in eastern China would increase soil CO2 emission, but decrease soil CH4 uptake in the old-growth forests.

Relationships of remnant trees to vascular undergrowth communities in the western cascades: a retrospective approach
About this Resource: Managers of federal forests in the US Pacific Northwest are charged with managing timber harvest while maintaining ecosystem functions and biological diversity associated with old, unmanaged forests. Thus, timber-orientated management is being replaced by ecosystem management, which includes leaving live trees (green trees), snags, and coarse woody debris after harvest. A retrospective approach was used to assess the potential effects of green-tree retention on vascular undergrowth in the western Cascades of Oregon. Fourteen natural 2-storied stands of remnant trees (>300 yr old) over 65-125 yr old regeneration were paired with neighbouring stands of the same age but lacking remnants. Species richness and cover of shrubs, all herbs, and late-successional shrubs and herbs did not differ systematically between stands with and without remnant trees. However, communities of herbs and shrubs varied with the percentages (percentage basal area/ha) of Douglas fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) in the regeneration, which varied with remnant densities. Regeneration densities and percentages of western hemlock in the regeneration were positively correlated with remnant tree densities. In contrast, percentages of Douglas fir in the regeneration and overall conifer volume were negatively correlated with remnant densities. Undergrowth cover and species richness was generally greater in relatively open Douglas fir dominated forests, which were associated with physiographically drier sites and fewer remnant trees. Results for these natural, 2-storied stands suggest that variable levels of green-tree retention in managed forests may provide for a diversity of undergrowth communities.

Distributions of rare mollusks relative to reserved lands in Northern California
About this Resource: In 1994 the Northwest Forest Plan identified several hundred relatively rare plant and animal species as "Survey and Manage" based in part on their presumed association with late-successional/old-growth forests. Other such species were given protection from grazing. However, broad-scale surveys for few of these species existed at that time. In 1999-2000 we evaluated the relationship of nine terrestrial molluscs (Ancotrema voyanum, Helminthoglypta herleini, H. talmadgei, Monadenia chaceana, M. churchi, M. fidelis klamathica, M. fidelis ochromphalus, Prophysaon dubium and Trilobopsis tehamana) to US Forest Service reserves in four National Forests in northern California. The nine molluscs were well distributed among reserved and non-reserved lands and showed no association with Late Successional Reserves, Congressionally Reserved, Administratively Withdrawn, or Matrix land allocations. However, the molluscs occurred more frequently than expected in Riparian Reserves when all other land allocations were combined. Our results are a step toward evaluating the protection that the Northwest Forest Plan affords these molluscs in northern California.

The spatial influence of Pseudotsuga menziesii retention trees on ectomycorrhiza diversity
About this Resource: Living retention trees are being used in managed forests to promote a variety of values, including the maintenance of biological diversity. Federal forest plans for the northwestern USA include guidelines that require the retention of a minimum of 15% basal area in harvest units, with the goal of facilitating the development of late-seral stand structure, which is an important habitat element for old-growth forest-dependent species. However, effective levels and patterns of green-tree retention are unknown. We present results of a treatment consisting of 15% basal area, evenly dispersed retention (15%D). We quantified changes in the ectomycorrhiza (EM) community after the 15%D treatment, both near and away from retention trees. Pretreatment samples were obtained between 1 and 24 months before tree harvest. Post-treatment samples were collected within 14-25 months of harvest. In areas 8-25 m from retention trees, there was a 50% decline in the number of EM types per soil core from before to after treatment. Soil cores taken >5 m from retention trees exhibited a shift in EM community structure. EM-type richness was positively correlated with fine-root-tip density. We demonstrate the potential for retention trees to act as refugia for recolonization of newly established seedlings by ectomycorrhizal fungi.

Legacy retention versus thinning: Influences on small mammals
About this Resource: Management strategies for promoting late-seral attributes in second-growth forest need evaluation for their efficacy in maintaining biodiversity, including complete forest-floor, small-mammal communities. Two common strategies in the Pacific Northwest are (1) management with thinnings to promote large trees with developed understories and (2) retention of legacies, defined as live trees, logs, and snags from the preceding forest, at harvest, followed by protection but not thinnings of the new stand. We compared small-mammal communities resulting from >65 yr of application of these strategies in the Puget Trough, Washington. We also compared these communities with the small-mammal communities found in old-growth, naturally young, and extensively managed forests elsewhere in western Washington. Forests managed with thinnings had 1.5 times the individual mammals and 1.7 times the mammal biomass of forests managed with legacies of coarse woody debris and snags-differences similar to those between old-growth and naturally young forest (1.2 times more individuals in old-growth) and old-growth and extensively managed forest (1.6 times more individuals in old-growth). Management strategy had a profound impact on community structure, with the Columbian mouse (Peromyscus oreas), the small mammal mostassociated with old growth, much reduced in Puget Trough forests (absent from most stands) and the creeping vole (Microtus oregoni) (a species commonly associated with early seral stages, but found in all seral stages in Washington) third-ranked in thinned stands but seventh ranked in legacy stands. The montane shrew (Sorex monticolus) was second-ranked, after Trowbridge's shrew (S. trowbridgii), in marked contrast to codominance by the southern red-backed vole (Clethrionomys gapperi), S. monticolus, and P. oreas in old growth. Thus, neither strategy produced communities typical of late-seral forests

Bird communities following high-severity fire: Response to single and repeat fires in a mixed-evergreen forest, Oregon, USA
About this Resource: Fire is a widespread natural disturbance agent in most conifer-dominated forests. In light of climate change and the effects of fire exclusion, single and repeated high-severity (stand-replacement) fires have become prominent land management issues. We studied bird communities using point counting in the Klamath-Siskiyou ecoregion of Oregon, USA at various points in time after one or two high-severity fires. Time points included 2 and 3 years after a single fire, 17 and 18 years after a single fire, 2 and 3 years after a repeat fire (15 year interval between fires), and >100 years since stand-replacement fire (mature/old-growth forest). Avian species richness did not differ significantly among habitats. Bird density was highest 17 and 18 years after fire, lowest 2 years after fire, and intermediate in repeat burns and unburned forest. Bird community composition varied significantly with habitat type (A =0.24, P <0.0001) with two distinct gradients in species composition relating to tree structure (live to dead) and shrub stature. Using indicator species analysis, repeat burns were characterized by shrub-nesting and ground-foraging bird species while unburned mature forests were characterized by conifer-nesting and foliage-gleaning species. Bird density was not related to snag basal area but was positively related to shrub height. Contrary to expectations, repeated high-severity fire did not reduce species richness, and bird densities were greater in repeat burns than in once-burned habitats. Broad-leaved hardwoods and shrubs appear to play a major role in structuring avian communities in the Klamath-Siskiyou region. In light of these results, extended periods of early seral broadleaf dominance and short-interval high-severity fires may be important to the conservation of avian biodiversity.

Input and output of dissolved organic and inorganic nitrogen in subtropical forests of South China under high air pollution
About this Resource: The nitrogen (N) emissions to the atmosphere and N deposition to forest ecosystems are increasing rapidly in Southeast Asia, but little is known about the fates and effects of elevated N deposition in forest ecosystems in this warm and humid region. Here we report the concentrations and fluxes of dissolved inorganic (DIN) and organic N (DON) in precipitation, throughfall, surface runoff and soil solution for three subtropical forests in a region of South China under high air pollution over two years (2004 and 2005), to investigate how deposited N is processed, and to examine the importance of DON in the N budget. The precipitation DIN input was 32–34 kg N ha−1 yr−1. An additional input of 18 kg N ha−1 yr−1 as DON was measured in 2005, which to our knowledge is the highest DON flux ever measured in precipitation. A canopy uptake of DIN was indicated in two young conifer dominated forests (72–85% of DIN input reached the floor in throughfall), whereas no uptake occurred in an old-growth broadleaf forest. The DON fluxes in throughfall were similar to that in precipitation in all forests. In the younger forests, DIN was further retained in the soil, with 41–63% of precipitation DIN leached below the 20-cm soil depth. Additionally, about half of the DON input was retained in these forests. The N retention in two young aggrading forests (21–28 kg N ha−1 yr−1) was in accordance with the estimates of N accumulation in biomass and litter accretion. In the old-growth forest, no N retention occurred, but rather a net loss of 8–16 kg N ha−1 yr−1 from the soil was estimated. In total up to 60 kg N ha−1 yr−1 was leached from the old-growth forest, indicating that this forest was completely N saturated and could not retain additional anthropogenic N inputs. We found that the majority of DIN deposition as well as of DIN leaching occurred in the rainy season (March to August) and that monthly DIN concentrations and fluxes in leaching were positively related to those in throughfall in all three forests, implying that part of the N leaching was hydrologically driven. Our results suggest that long-term high N deposition has caused elevated N leaching in all three forest types although most pronounced in the old-growth forest where wood increment was negligible or even negative. N availability even exceeded the biotic N demand in the young aggrading forests, with intensive rain in the growing season further enhancing N leaching in these forests.

A synthesis of scale-dependent ecology of the endangered mountain caribou in British Columbia, Canada
About this Resource: Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that live in highprecipitation, mountainous ecosystems of southeastern British Columbia and northern Idaho. The distribution and abundance of these caribou have declined dramatically from historical figures. Results from many studies have indicated that mountain caribou rely on old conifer forests for several life-history requirements including an abundance of their primary winter food, arboreal lichen, and a scarcity of other ungulates and their predators. These old forests often have high timber value, and understanding mountain caribou ecology at a variety of spatial scales is thus required to develop effective conservation strategies. Here we summarize results of studies conducted at three different spatial scales ranging from broad limiting factors at the population level to studies describing the selection of feeding sites within seasonal home ranges of individuals. The goal of this multi-scale review is to provide a more complete picture of caribou ecology and to determine possible shifts in limiting factors across scales. Our review produced two important results. First, mountain caribou select old forests and old trees at all spatial scales, signifying their importance for foraging opportunities as well as conditions required to avoid alternate ungulates and their predators. Second, relationships differ across scales. For example, landscapes dominated by roads and edges negatively affect caribou survival, but appear to attract caribou during certain times of the year. This juxtaposition of fine-scale behaviour with broad-scale vulnerability to predation could only be identified through integrated multi-scale analyses of resource selection. Consequently we suggest that effective management strategies for endangered species require an integrative approach across multiple spatial scales to avoid a focus that may be too narrow to maintain viable populations.Abstract in Norwegian / Sammendrag:Skala-avhengig økologi og truet fjellvillrein i Britisk ColumbiaFjellvillreinen i de nedbørsrike fjellområdene i sørøstre Britisk Columbia og nordlige Idaho som er en truet økotype av skogsreinen (Rangifer tarandus caribou), har blitt kraftig redusert både i utbredelse og antall. Mange studier har vist at denne økotypen er avhengig av vinterføden hengelav i gammel barskog hvor det også er få andre klovdyr og dermed få predatorer. Slik skog er også viktige hogstområder, og å forstå økologien til fjellvillreinen i forskjellige skaleringer er derfor nødvendig for å utvikle forvaltningsstrategier som kan berge og ta vare på denne reinen. Artikkelen gir en oversikt over slike arbeider: fra studier av begrensende faktorer på populasjonsnivå til studier av sesongmessige beiteplasser på individnivå. Hensikten er å få frem et mer helhetlig perspektiv på fjellvillreinen og finne hvordan de begrensende faktorene varierer etter skaleringen som er benyttet i studiet. Oversikten vår frembragte to viktige resultater; 1) Uansett skalering så velger dyrene gammel skog og gamle trær. 2) Dyrenes bruk av et område kan variere med benyttet skalering, for eksempel vil landskap utbygd med veier og hogstflater være ufordelaktig for overlevelsen, men synes likevel å kunne tiltrekke fjellvillreinen til visse tider av året. Forholdet mellom atferd ut fra fin-skalering og stor-skalering sårbarhet hva gjelder predasjon, ville kun blitt avdekket ved flere-skaleringsanalyse av hvordan ressursene benyttes. Ut fra dette foreslår vi at forvaltningsstrategier for truete bestander som eksempelvis fjellvillreinen, må baseres på tilnærminger ut fra ulike skaleringer for å hindre at et for snevert perspektiv kan begrense muligheten for vedvarende levedyktighet.

Spatial and temporal changes of Hyrcanian forest in Iran
About this Resource: Original old-growth northern forests of Iran are essential sources of genetic variation, biodiversity, commercial woody products, and various environmental services (e.g., ground water reservation, auxiliary forest products provision, wildlife habitation, and erosion control). Today, the forests are depleting rapidly due to population growth, and associated socio-economic problems, industrial development, urbanism, and more recently intensive/irregular tourism. Satellite image processing and other geo-spatial tools have been used in Iran from the early 80’s to map the vegetative attributes of forests for environmental resource monitoring. This paper aims to build up a basic assumption of when and how the spectral, spatial and temporal features of satellite-borne remote sensing have been applied for the sustainable resource monitoring of the Caspian forests of Iran. To this end, available literature will be reviewed, specific features of the studies discussed in brief, and the future prospects for remote sensing-aided delineation of structural and functional characteristics of the forests will be outlined.

Canopy light and the distribution of hemlock dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones subsp. tsugense) aerial shoots in an old-growth Douglas-fir/western hemlock forest
About this Resource: Hemispherical photography was used to quantify the relationship between canopy light and the distribution of hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) aerial shoots in an old-growth Douglas fir/western hemlock (Pseudotsuga menziesii/Tsuga heterophylla) forest to determine if aerial shoots only occur in higher light environments in the upper canopy. The Wind River Canopy Crane provided 3-dimensional access by lowering a gondola into gaps between trees and stopping at 5 m intervals and sampling all trees around the gap at that height. A total of 89 dwarf mistletoe infections in live branches were sampled on 14 trees from 18 to 60 m height. Forty-one infections had no aerial shoots whereas 48 had aerial shoots. All infections above 50 m had shoots, while all infections below 30 m (except one) had none. There were no aerial shoots at infections exposed to estimated insolation (calculated as the sum of indirect and direct site factors weighted for diffuse and direct shortwave insolation) of 1000 MJ m-2yr-1, while all infections exposed to insolation of above 3200 MJ m-2yr-1 had aerial shoots. Height and light were highly correlated, but between 30 and 50 m the light environment became especially heterogeneous, with a 50% probability of aerial shoots occurring at 40 m, or at 2200 MJ m-2yr-1. A complex of biotic and abiotic factors may account for the correlation of high light and aerial shoot occurrence in the field, because laboratory studies have shown that dwarf mistletoe produces the most aerial shoots in low light and at high temperature. In this tall, multi-layered canopy, the source of the seed rain from western hemlock dwarf mistletoe was above the bulk of the western hemlock foliage, perhaps another explanation for the fast spread and intensification of mistletoe in old-growth forests.

In situ physiological monitoring of Lobaria oregana transplants in an old-growth forest canopy
About this Resource: Lobaria oregana (lettuce lung lichen) is an abundant nitrogen-fixing cyanolichen in old-growth Douglas-fir [Pseudotsuga menziesii] forests of the Pacific Northwest (USA). In this study, we used the Wind River Canopy Crane Research Facility in the southern Washington Cascades, to study nitrogenase activity, photosynthesis, and growth to clarify the potential for Lobaria to contribute fixed nitrogen to these forests and to better understand the ecological factors that determine the distribution of Lobaria. Pendants of Lobaria were placed at three positions in the canopy: top (62 m above the ground), middle (39 m), and bottom (2 m). There was a complex pattern of seasonal and spatial variation. Highest growth was found at the middle position where there was a 19.3% increase in dry weight over the 13-month study period. Lichens at the bottom position died after transplanting. Nitrogenase activity was consistently higher in the middle position and averaged 115 nmol C2H4 g-1 h-1 for wet season measurements (February, March, and November) with a range of 0-310 nmol C2H4 g-1 h-1. Photosynthesis activity averaged 0.322 mg CO2 g-1 h-1 for the wet season with a range of 0-0.801 mg CO2 g-1 h-1. Activities were strongly correlated with hydration except that hydration >200% inhibited photosynthesis. Laboratory experiments showed that photosynthesis increased at photosynthetic photon flux densities of up to 1000 micro mol m-2 s-1. This study supports the conclusion that Lobaria is a source of nitrogen input for these forests and addresses how the physiological activities of Lobaria respond both spatially and temporally to the extremely variable environment within the canopy.

Fire history in coast redwood forests of the Mendocino Coast, California
About this Resource: We reconstructed fire history in old-growth coast redwood (Sequoia sempervirens) stands along an ocean-to-inland gradient in Jackson Demonstration State Forest on the Mendocino Coast in northern California, USA. Fire history was reconstructed for the past two to four centuries using fire scars recorded in tree rings. Surface fires were frequent disturbances in all stands prior to the early twentieth century. Composite mean fire-free intervals aggregated within stands varied from 6 to 20 years, and point mean fire-free intervals averaged within trees varied from 9 to 20 years. Fires ceased in the early 20th century coincident with the advent of organized fire suppression efforts beginning in the 1930s. Fire frequency did not vary significantly along the ocean-inland gradient. Although several of the inland stands tended to record shorter intervals between fires, there was high variability among sites. These and analogous fire-scar data from other studies across the range of coast redwood forests suggest that fire frequencies have been underestimated in some past assessments. A principal reason is that fire-scar records on coast redwood trees are difficult to locate because of inadequate preservation compared to other species that experienced surface fires. Cessation of surface fires has resulted in shifts in fuel and forest structure over recent decades, and the fire history reconstructed by this study provides both guidelines and justification for ecological restoration efforts in coast redwood forests of this region.

Vertical distribution of dominant epiphytes in Douglas-fir forests of the central Oregon Cascades
About this Resource: The canopies of old-growth Douglas-fir forests support a diversity of epiphytic lichens and bryophytes. We quantified the vertical distributions of six dominant epiphytes throughout the crowns of large Tsuga heterophylla (46-57 m tall) and Pseudotsuga menziesii (60-78 m tall) trees in five forest stands of the central Oregon Cascades. There were no major differences in epiphyte distribution between the two tree species, but epiphytes on T. heterophylla generally peaked in abundance at heights 10-20 m below those on P. menziesii. Alectorioid lichens were most abundant in the upper crowns but scarce in the lower crowns. The fruticose green algal lichen Sphaerophorus globosus was evenly distributed throughout the crowns. The cyanolichen Lobaria oregana and the moss Antitrichia curtipendula were most abundant in middle crowns. Lobaria pulmonaria was most abundant in the lower-middle crowns. It was scarce or absent in the upper crowns. The moss Isothecium myosuroides was also scarce or absent in the upper crowns. It was most abundant in the lower crowns. The vertical patterns described in this study are not representative of all old-growth Douglas-fir forests. In wetter forests, bryophytes are dominant throughout the canopy. In drier forests, alectorioid and other green algal lichens extend farther down in the canopy, and bryophytes and cyanolichens are restricted to the lower canopy

Characteristics of young forests used by spotted owls on the western Olympic Peninsula, Washington
About this Resource: Although the dependence of spotted owls (Strix occidentalis) on older forests has been well documented, the specific attributes of comparatively younger forests used by owls have not been described in some regions. We collected habitat data at locations used by spotted owls tracked in an intensive radio-telemetry study to develop descriptions of these forests on the western Olympic Peninsula, Washington. After addressing the effects of triangulation error on the placement of our vegetation sampling plots, we collected data at all 16 telemetry locations that could be clearly associated with non-old-growth habitat, as well as 16 random locations. Owl locations were divided into 2 groups to reflect single-use (only one radio location within the error polygon) and multiple-use sites (gtoreq2 radio locations within the error polygon) within home ranges. Vegetation data collected in three arrays of variably-sized plots included measures of stem and snag density (by diameter class), canopy cover, and cover of downed wood and shrubs. Our analyses indicated that single-visit and random locations did not differ with respect to the variables we recorded. However, both differed from multiple-use locations in abundance of larger snags, and amount of canopy closure. A logistic regression model indicated that multiple-use sites could be reliably distinguished from single-use and random locations based on the greater number of snags gtoreq51 cm diameter at breast height (dbh) and gtoreq70% canopy closure. Younger forests managed for spotted owl foraging habitat in this region should be in the understory reinitiation stage of stand development, have gtoreq70% canopy closure, and contain gtoreq4 snags/0.4-ha that are gtoreq51 cm dbh. The habitat definitions we propose may not be applicable to other areas characterized by different forest types and prey assemblages

Commercial moss harvest in northwestern Oregon: Describing the epiphyte communities
About this Resource: This paper describes the epiphytes impacted by commercial moss harvest in northwestern Oregon. Commercially harvestable epiphytes were sampled on hardwood tree trunks and shrub stems from 10 sites in each of the Cascade and Coast Ranges. Fifty species of mosses, hepatics, lichens, and vascular plants were found in over 500 epiphyte mats. Seven taxa were defined as "target" species, due to high frequency of occurrence and abundance. Six species were defined as "incidental" due to lower frequency and biomass but a high association with target species. The remaining 37 species were defined as "nontarget" species that would generally be avoided by commercial harvesters, but are often accidentally harvested. In the Cascade Range, Neckera douglassii was the most abundant harvestable epiphyte, with an average of 170 kg/ha of dry-weight harvestable material across ten sites. In the Coast Range, Isothecium myosuroides was most abundant, with an average of 530 kg/ha of dry-weight harvestable material. All harvestable epiphytes were less abundant in stands with high conifer basal area. Target species were most abundant in stands with relatively high hardwood basal area, except Antitrichia curtipendula which was most abundant in younger stands. Some nontarget and incidental species were also most abundant on tree trunks. To protect rare species and epiphyte diversity, moss harvest should be directed away from older forests with mature hardwoods and toward younger, mixed forests. Moss harvest should be prohibited in areas being managed toward "old growth" conditions to facilitate the development of complex epiphyte communities requiring substrate continuity

Vertical profile of epiphytes in a Pacific Northwest old-growth forest
About this Resource: The vertical stratification of epiphytes is a striking feature of Northwestern forests that surely influences the distribution of other organisms in the canopy. We are just now learning how and why the stratification varies from place to place. Functional groups of epiphytes were stratified with height in an old-growth Pseudotsuga-Tsuga forest in the following order, from the ground up: bryophytes, cyanolichens, and alectorioid lichens. Other macrolichens (mainly green-algal foliose) were found throughout the vertical profile, but their relative abundance peaked in the middle to upper canopy. Cyanolichens (mainly Lobaria oregana) were concentrated in the "light transition zone." The light transition zone is the range of heights in which we found abrupt transitions in light transmittance by the canopy. This zone extends from about 13 to 37 m in height, in an overall canopy height of 50-60 m. Bryophytes were concentrated between the ground and the middle of the light transition zone. The biomass of epiphytic macrolichens was about 1.3 metric tons/ha, composed of approximately 42% cyanolichens, 28% alectorioid lichens, and 30% other lichens. We draw the following methodological conclusions. Using quadrats as windows from a suspended gondola overestimates the relative abundance of alectorioid lichens and underestimates cyanolichens and other lichens. Using 14, 2-m radius lichen litter plots is barely adequate to represent the epiphytic macrolichens of an old-growth stand. Ground-based canopy density measurements (photographic and densiometer) are insufficient to characterize the openness of a vertical transect, because of interference from understory vegetation

Regional and temporal patterns of litterfall in tropical South America
About this Resource: The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91Mg/ha/yr. Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg/ha/yr. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91Mg/ha/yr). Litterfall declines significantly with increasing N:P. We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg/ha/yr (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40Mg/ha/yr (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall is negatively related to the N:P ratio, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.

Overstory and shrub influences on seedling recruitment patterns in an old-growth ponderosa pine stand
About this Resource: Seedling recruitment in an old growth ponderosa pine (Pinus ponderosa) stand in central Oregon, USA, was studied to determine its relationship with overstorey trees and nearby shrubs, and to identify the spatial patterns resulting from these relationships. Results showed that the influence of adjacent vegetation was greatest among smaller size classes of regeneration. The strongest relationship between overstorey basal area, and germinant and seedling density was observed when calculated at a very local scale (5-m radius). Seedling and germinant densities were also adversely affected by adjacent saplings but were positively associated with shrubs. Spatial analysis revealed significant aggregation of germinants, seedlings and saplings, with the intensity of aggregation decreasing from smaller to larger size classes. These results suggest that regeneration is most sensitive to adjacent vegetation during the early stages, that the facilitative influence of shrubs diminishes relative to their competitive effect once regeneration reaches the sapling stage, and that the early aggregated condition of regeneration gradually transforms towards a more regular pattern as stand development progresses.

Seedfall, seed germination, and initial survival and growth of seedlings of Thuja plicata in southwestern British Columbia
About this Resource: Reasons for the relative absence of Thuja plicata regeneration in the old growth Thuja plicata - Tsuga heterophylla forests close to Vancouver, British Columbia, were assessed by measuring seedfall and applying Thuja seeds to small plots. All measurements were replicated in two different sites. The small (0.5 m2) plots were established in 2 canopy cover conditions (clearcut and forest). 3 seedbed conditions (mineral soil, burned forest floor, and undisturbed forest floor), and 2 mammal and bird seed predation conditions (with and without). Each canopy cover, seedbed, and seed predation combination was replicated 15 times in each study site. Large numbers of viable seeds (>200/m2) fell in 1990/91 and again in 1994/95. Seed germination decreased in the order burn > mineral soil > forest floor; forest > clearcut; and without predation > with predation. After 3 growing seasons, of the 100 seeds applied to each plot, an average of only 1-2 seedlings had survived. This number of surviving seedlings decreased in the order - burn > mineral soil > forest floor, and clearcut > forest, but was not influenced by predation. After 3 growing seasons. seedling growth tended to decrease in the order - burn > forest floor > mineral soil; clearcut > forest; and without predation > with predation. It was concluded that the relative lack of regenerating Thuja seedlings in the study area forests was not due to a lack of viable seeds. Although a lack of suitable seedbeds and the presence of the forest canopy reduce the number of seedlings in undisturbed forests, this number should still be substantial. The observed relative lack of regenerating Thuja seedlings must therefore result from other factors which were not considered in the present study

Arthropods from ‘ōhi‘a lehua (Myrtaceae: Metrosideros polymorpha), with new records for the Hawaiian Islands
About this Resource: This paper presents new records, range extensions, and a checklist of arthropod species found associated with the most common and widespread native tree in the Hawaiian Islands, ‘öhi‘a lehua (Myrtaceae: Metrosideros polymorpha Gaudichaud-Beaupré). Metrosideros polymorpha is found on all the main islands, naturally occurs from sea level to tree line (>2000 m), in dry, mesic, and wet forests, and is the canopy dominant in old growth and the first woody colonist on recent basaltic lava flows (Dawson & Stemmerman, 1990). Numerous insect species use ‘öhi‘a lehua as a resource for either food or habitat space, and it may have the largest fauna of any native plant (Southwood, 1960; Stein, 1983). Metrosideros is an important, year-round nectar resource for native bees, moths, thrips and other insects, and for native nectarivorous birds, such as the ‘apapane (Himatione sanguinea), ‘i‘iwi (Vestiara coccinea), and ‘akohekohe (Palmeria dolei). Metrosideros also provides important habitat for birds that forage for arthropod prey in the foliage (e.g., ‘akepa [Loxops coccineus]) and bark (e.g., Hawai‘i creeper [Oreomystis mana]). It can be argued that M. polymorpha is the backbone of Hawaiian forests and one of the most important resources for the long-term stability of ecosystems and watersheds in the islands.

Optimal Forest Strategies for Addressing Tradeoffs and Uncertainty in Economic Development under Old-Growth Constraints
About this Resource: In Canada, governments have historically promoted economic development in rural regions by promoting exploitation of natural resources, particularly forests. Forest resources are an economic development driver in many of the more than 80% of native communities located in forest regions. But forests also provide aboriginal people with cultural and spiritual values, and non-timber forest amenities (e.g., biodiversity, wildlife harvests for meat and fur, etc.), that are incompatible with timber exploitation. Some cultural and other amenities can only be satisfied by maintaining a certain amount of timber in an old-growth state. In that case, resource constraints might be too onerous to satisfy development needs. We employ compromise programming and fuzzy programming to identify forest management strategies that best compromise between development and other objectives, applying our models to an aboriginal community in northern Alberta. In addition to describing how mathematical programming techniques can be applied to regional development and forest management, we conclude from the analysis that no management strategy is able to satisfy all of the technical, environmental and social/cultural constraints and, at the same time, offer aboriginal peoples forest-based economic development. Nonetheless, we demonstrate that extant forest management policies can be improved upon.

Reforestation and topography affect montane soil properties, nitrogen pools, and nitrogen transformations in Hawaii
About this Resource: Land use changes, such as deforestation and reforestation, modify not only the organisms inhabiting affected areas, but also above-and belowground environments. Topography further influences local vegetation and environment. Effects of topography and re-establishment of N-fixing koa (Acacia koa A. Gray) trees in +100-yr-old montane grassland on surface soil properties, N pools, and N transformations were assessed using standard and 15N-isotope pool dilution methods. Data were collected for soils on slopes and in drainage bottoms located in grassland, under 9- to 11-yr-old planted koa, and in nearby old-growth koa-ohia (Metrosideros polymorpha Gaud.) forest. Soil under planted koa had significantly lower fine soil bulk density and pH than soil in grassland, and had concentrations of total C, total N, and extractable Mg and C/N ratio intermediate between grassland and forest. Topographic position affected pH and concentrations of total C, total N, and extractable P. Ten years after koa trees were re-introduced to grassland, the concentration of soil NH4(+)-N had increased above levels found even in intact forest, and the concentration of NO3(-)-N was intermediate between forest and grassland. Ammonium dominated the inorganic N pools in grassland soil and NO3(-) dominated in forest soil. Under planted koa, NH4(+) domination was beginning to give way to NO3(-) domination. Soil microorganisms were potentially strong competitors for inorganic N on grassland slopes where they immobilized nearly all the inorganic N that was produced during short- and medium-term field incubations, thus leaving little for plant growth. Re-establishment of koa trees increased soil N availability.

Influence of partial harvesting on stream temperatures, chemistry, and turbidity in forests on the Western Olympic Peninsula, Washington
About this Resource: Stream temperatures, chemistry and turbidity were monitored in two partially harvested (7-33%) watersheds, Rock and Tower creeks, and an uncut old-growth watershed, West Twin Creek in the Hoh River Valley on the Olympic Peninsula, Washington. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was replanted in the harvested areas and red alder (Alnus rubra Bong.), a nitrogen fixer, dominated the riparian areas in the sampling sites on Rock and Tower creeks. We collected grab stream water samples monthly, from May 1996 to June 1998 and analyzed them for pH, electrical conductivity, total N and P, and major cations and anions. Stream temperatures were monitored continuously and turbidity was monitored monthly from May 1997 to June 1998. Partial harvesting had little influence on stream temperature, chemistry and turbidity 11-15 years after harvesting. Stream temperatures were more seasonally variable in the harvested streams compared to the unharvested old-growth site with an average summertime maximum elevated by 3.5degreeC. Maximum stream temperatures did not exceed 16degreeC in any stream and therefore salmonid species are not likely to be affected. There were significant differences in concentrations of some cations, anions and EC between the old-growth and the partially harvested watershed streams, but in most cases concentrations were actually higher in the unharvested watershed. Nitrate concentrations and stream turbidity were not significantly higher in the harvested watersheds

The vertical occurrence of small birds in an old-growth Douglas-fir-western hemlock forest stand
About this Resource: The vertical occurrence of the small bird assemblage (songbirds, small woodpeckers, nighthawks, and swifts) in a ~4 ha stand within the T.T. Munger Research Natural Area, Washington, USA, a 500-year-old Douglas-fir-western hemlock (Pseudotsuga menziesii-Tsuga heterophylla) forest, was quantified to characterize this assemblage and determine whether birds are vertically stratified within the canopy. We used a gondola suspended from a construction crane to count birds in a weekly series of vertically stratified fixed-area point counts, 5-minute, 30 m radius, in the lower (0-20 m), mid (21-40 m) and upper (41-60+ m) canopy. Data are from 21 March 1996 to 21 March 1999, and included 121 survey days (mean 40 counts/year, March-June 42, July-October 46, November-February 33). Twenty-nine species of birds were detected in the plots; the 20 most common were used for analysis. Fifteen of these species were detected significantly more often in one zone of the canopy. Timber foliage insectivores, air insectivores, timber seed-eaters, and most low understorey herbivore-insectivores were stratified within the canopy. Bark insectivores (except brown creeper (Certhia americana)) and omnivore-scavengers (except gray jay (Perisoreus canadensis)), however, were not stratified within the canopy. The number of bird detections shifted to the upper canopy during winter. One species was generally restricted to the lower canopy, and five species were restricted to the upper canopy, whereas no species were found exclusively in the mid-canopy. The small bird assemblage of this old-growth forest stand was vertically and seasonally patterned and the vertical forest structure, particularly within the upper canopy, reflects these patterns.

Folivory of vine maple in an old-growth Douglas-fir-western hemlock forest
About this Resource: Folivory of vine maple (Acer circinatum) was documented in an old-growth Douglas-fir-western hemlock (Pseudotsuga menziesii-Tsuga heterophylla) forest in southwest Washington, USA. Leaf consumption by lepidopteran larvae was estimated with a sample of 450 tagged leaves visited weekly from 7 May to 11 October 1999, the period from bud break to leaf drop. Lepidopteran taxa were identified by handpicking larvae from additional shrubs and rearing to adult. Weekly folivory peaked in May at 1.2%, after which it was 0.2% to 0.7% through mid October. Cumulative seasonal herbivory was 9.9% of leaf area. The lepidopteran folivore guild consisted of at least 22 taxa. Nearly all individuals were represented by eight taxa in the Geometridae, Tortricidae, and Gelechiidae. Few herbivores from other insect orders were observed, suggesting that the folivore guild of vine maple is dominated by these polyphagous lepidopterans. Vine maple folivory was a significant component of stand folivory, comparable to ~66% of the folivory of the three main overstorey conifers. Because vine maple is a regionally widespread, often dominant understorey shrub, it may be a significant influence on forest lepidopteran communities and leaf-based food webs.

A habitat network for terrestrial wildlife in the Interior Columbia Basin
About this Resource: Habitat managers need information about landscape conditions in relation to the composite requirements of species that deserve attention in conservation planning. Consequently, we characterized and mapped a broad-scale network of habitats for five suites of terrestrial vertebrates in the 58 million-ha Interior Columbia Basin (Basin). These five suites, referred to as Families, are composed of 44 species whose habitats have declined strongly from historical (circa 1850-1890) to current periods in the Basin, and thus are of conservation focus. Two of the five Families consist of species that depend on old forests. Species in another Family depend on early-seral forests. Species in the remaining Families depend on sagebrush-steppe or open canopy sagebrush and grasslands. For each Family, we characterized current habitat conditions at the scale of the watershed (mean size of 22 500 ha). Each watershed was classified as one of three conditions. Watersheds in Condition 1 contained habitats whose quality or abundance have changed little since the historical period. By contrast, watersheds in Condition 2 or 3 contained habitats that have changed from historical conditions, but in different ways. Watersheds in Condition 2 had habitats of high abundance but moderate resiliency and quality, whereas watersheds in Condition 3 contained habitats of low abundance or low resiliency and quality. The majority of watersheds (59-80%) were in Condition 3 for all five Families, whereas the lowest percentage (5-25%) of watersheds was in Condition 2 for four of five Families. Connectivity among watersheds for all Families appeared low in many parts of the Basin due to spatial gaps associated with areas of habitat extirpation. Our condition maps constitute a broad-scale network of habitats that could be useful for developing multi-species research hypotheses and management strategies for the Basin.

Decaying logs and habitat heterogeneity: implications for bryophyte diversity in Western Oregon forests
About this Resource: Bryophyte species richness on a variety of forest substrates in western Oregon, USA, including decaying logs, mineral soil, rocks, and hardwood tree bases was examined to inventory byrophytes and survey for species designated for federal agency protection, to quantify and evaluate the relative contributions of the range of bryophyte substrates towards bryophyte richness, and to examine whether bryophyte richness was associated with stand age. Of all substrates, logs in advanced stages of decay had the richest bryophyte flora and supported the greatest percentage of bryophyte landscape-level diversity. Such logs also contributed the greatest number of liverworts unique to a substrate type, while mineral soil contributed the greatest number of unique mosses. Hardwood bases, humus and rocks also added bryophytes not found on any other substrate type. Consequently, habitat heterogeneity increases bryophyte diversity in western Oregon forests, and fostering biological and structural legacies characteristic of old growth in young managed stands would contribute toward forest management from an ecosystem approach by fostering habitat complexity and biodiversity in the course of harvesting timber.