Salix Planifolia Research Articles

A Multivariate Approach to Ethnopharmacology: Antidiabetic Plants of Eeyou Istchee.

An ethnopharmacological metanalysis was conducted with a large database available on antidiabetic activities of plant foods and medicines from the northern boreal forest, which are traditionally used by the indigenous Cree of James Bay, Quebec, Canada. The objective was to determine which bioassays are closely associated with the traditional knowledge of the Cree and which pharmacological metrics and phytochemical signals best define these plants and their groups. Data from 17 plant species, ethnobotanically ranked by syndromic importance value for treatment of 15 diabetic symptoms, was used along with 49 bioassay endpoints reported across numerous pharmacological studies and a metabolomics dataset. Standardized activities were separated into primary, secondary and safety categories and summed to produce a Pharmacological Importance Value (PIV) in each of the three categories for each species. To address the question of which pharmacological metrics and phytochemical signals best define the CEI anti-diabetes plants, multivariate analyses were undertaken to determine groupings of plant families and plant parts. The analysis identified Larix larcina as the highest PIV species in primary assays, Salix planifolia in secondary assays, and Kalmia angustifolia in safety assays, as well as a ranking of other less active species by PIV. Multivariate analysis showed that activity in safety PIV monitored mainly with cytochrome P450 inhibition patterns best reflected patterns of traditional medicine importance in Cree traditional knowledge, whereas potent primary bioactivities were seen in individual plants determined to be most important to the Cree for anti-diabetes purposes. In the secondary anti-diabetes assays, pharmacological variability was better described by plant biology, mostly in terms of the plant part used. Key signal in the metabolomics loadings plots for activity were phenolics especially quercetin derivatives. Traditional Indigenous knowledge in this analysis was shown to be able to guide the identification of plant pharmacological qualities in scientific terms.

Effects of one dark septate endophytic fungal and two Helotiales strains on the growth of plane-leaved willow (Salix planifolia) cuttings on iron ore waste rock

Plants maintain beneficial mutualistic relationships with the mycobiont communities found in their rhizosphere, leading to an increase in plant productivity and health. In nutrient-depleted substrates like mine tailings, mycobiont inoculation is often recommended to help restore a successful plant cover. Our 15-week greenhouse experiment aimed to assess the individual effects of a dark septate endophyte (Phialocephala fortinii C.J.K. Wang & H.E. Wilcox #4 (KX611529)) and two Helotiales strains (Rhizoscyphus ericae (D.J. Read) W.Y. Zhuang & Korf #22 (EU221877) and Meliniomyces sp. #1 (KT275679)) on the growth of plane-leaved willow (Salix planifolia Pursh) cuttings on sterilized and unsterilized waste rock. Rhizoscyphus ericae increased shoot biomass of cuttings on sterilized waste rock, whereas Meliniomyces sp. had a positive effect on cuttings grown on unsterilized waste rock. However, P. fortinii strain had no effect on the survival rate, shoot production, and biomass production of S. planifolia cuttings. This study demonstrates that controlled inoculation with ecologically well-adapted mycobionts could promote plant establishment and productivity on abandoned waste rock and could be an efficient and integrated biotechnological approach for ecological restoration of Canadian mining boreal ecosystems.

An ecological microsystem to treat waste oil contaminated soil: Using phytoremediation assisted by fungi and local compost, on a mixed-contaminant site, in a cold climate

As a result of anthropization and industrialization, northern remote communities face issues of soil contamination by mixtures of organic and inorganic contaminants. Soil bioremediation in cold environments is particularly challenging because of slower degradation rates, slower production of biomass for phytoextraction of trace elements (TEs), and remoteness, which can complicate logistics and inflate costs. This study evaluated a decontamination approach integrating indigenous willows, fungi and compost in a northern community. The site was a waste oil pit and its soil was initially contaminated with petroleum hydrocarbons (PHC) exceeding 200 g kg−1 and TEs including As, Cd, Co, Cr, Cu, Pb and Zn. In under five years, 65 and 75% of PHC (C6-C50 and >C50) were degraded, compared to 27 and 13% for the untreated control soil. We found contrasting TE translocation patterns to the aboveground biomass for the willow species used (Salix planifolia and Salix alaxensis), as well as distinctive rooting strategies. Hazard quotients were calculated to assess the risk plant material could pose to local wildlife. The highest TE concentration measured was Zn in S. planifolia, which exceeded Canadian soil guidelines. Results indicate toxicity risks to animals linked to TEs in Salix spp. leaves is generally unlikely. The fungus Trametes versicolor inoculated into the soil did not fruit, however fruiting bodies of Psathyrella sp. were observed consistently (four out of five years). Biological tests indicated that in five growing seasons soil toxicity significantly decreased compared to the untreated soil used as control. This was demonstrated by vegetation cover (137 vs 11% cover), toxicity assays on earthworms (Eisenia andrei) (0 vs 33% mortality) and barley seed germination (Hordeum vulgare) (86 vs 62% germination). The proposed decontamination approach, without the use of synthetic fertilizers, is promising for the PHC remediation of mixed-contaminants on cold climate sites.

Local fungi, willow and municipal compost effectively remediate petroleum-contaminated soil in the Canadian North

Low energy-input alternatives based on locally available products are needed for treating petroleum-hydrocarbon spills in northern regions. We tested the efficacy of three local biological components (municipal compost, white-rot fungus: Pleurotus ostreatus and willow: Salix planifolia) to remediate diesel-contaminated soils in a subarctic climate (Whitehorse, YT, Canada), and compared their efficacy to natural attenuation and chemical fertilizers (industry standard). After the first growing season, biologically amended treatments (BAT) that contained >2 biological components, had decreased 69–73% of the diesel's F2 fraction (C10-C16), which is more than natural attenuation or fertilizer (48 and 51%). By the third growing season, the BAT dropped below the Canadian Council of Ministers of the Environment's (CCME) Agricultural & Residential/Parkland guideline (<150 mg kg−1) and 86% of willows had survived and developed extensive roots. MiSeq amplicon sequencing of fungal (ITS) and bacterial (16S) rRNA genes showed the BAT's microbial communities were significantly more abundant and diverse. We found 132 bacterial and 35 fungal genera unique to the BAT. Readily-available local biological components such as municipal compost, fungi and willows may provide an effective alternative to applications of imported chemical fertilizers for the bioremediation and revegetation of diesel-contaminated soil in northern environments.

Revisiting the role of migratory caribou in the control of shrub expansion in northern Nunavik (Québec, Canada)

Widespread shrub expansion has been observed at the circumpolar scale in response to climate change. This phenomenon could be inhibited by large herbivores through selective browsing that reduces shrub growth. Our objective was to assess the dynamics of shrub species in the Deception Bay area, in Nunavik (Quebec, Canada), a region in the summer range of the Riviere-aux-Feuilles migratory caribou herd. We surveyed abundance and stem mortality of all shrub species along systematically located transects in a 54 km2 area. Our results showed that shrubs covered 11.5% of the area, and were dominated by prostrate Betula glandulosa (8.7%). Stem mortality of established individuals was greater for Salix planifolia (45.6%) and Salix glauca (46.5%) than for B. glandulosa (9.3%). Using dendrochronological analysis, we determined the age structure of the two dominant erect shrub species in ten 10 m × 10 m plots. We recorded a high number of B. glandulosa and, to a lesser extent, of S. planifolia recruits (71.0 and 4.6 per 100 m2, respectively) established after 1999, when the Riviere-aux-Feuilles herd was abundant. Thus, our results do not support the hypothesis that large herbivores counteracted the positive effects of climate change on shrub recruitment. However, since the structure of the recruits are prostrate rather than erect, as is usually observed with shrub expansion in the warming Arctic, it is likely that herbivory, and/or, the harsh climate, is constraining habitat change.

Impacts of recreation management practices in a subalpine wetland system dominated by the willow plant, Salix planifolia

Wetland habitat in the subalpine Rocky Mountains is an area of high biodiversity and includes many species of willow. These willow-dominated communities are often used for both summer and winter recreation. The maintenance of winter recreation trails has the potential to disturb wetland vegetation and compromise the long-term persistence of the wetland. In Breckenridge, Colorado, willow plants are clipped in October to a uniform height to prevent stems from protruding through the snow onto the ski trails, and large grooming tractors compact the snow on the trails. Our objective was to investigate the impact of winter recreation trail maintenance on growth and reproductive output of Salix planifolia (common names: planeleaf or diamondleaf willow) and to determine impacts on community diversity in a willow-dominated wetland system. Catkin production, plant height, and branch elongation were evaluated in meter-squared quadrats within paired belt transects both inside and outside a ski trail during the growing seasons of 2008 and 2009. In addition, percent cover of total vegetation was estimated for each species to calculate species richness and diversity. We found that maintenance of winter trails reduced catkin production and limited willow growth. Additionally, winter trail maintenance may have promoted the introduction of invasive species within the willow community. The activities associated with winter trail maintenance could interfere with the long-term persistence of the willow community adjacent to ski trails and should be considered when planning new trails in or along a wetland ecosystem.

Phytoremediation of cadmium and lead-polluted watersheds

Abandoned hard rock mines and the resulting acid mine drainage (AMD) are a source of vast, environmental degradation that are toxic threats to plants, animals, and humans. Cadmium (Cd) and lead (Pb) are metal contaminants often found in AMD. In our mine outwash water samples, Cd and Pb concentrations were 300 and 40 times greater than EPA Aquatic Life Use water quality standards, respectively. We tested the phytoremediation characteristics, accumulation and tolerance of Cd and Pb contamination, for annual aboveground biomass harvest of three montane willows native to the Rocky Mountains: Salix drummondiana, S. monticola, and S. planifolia. We found S. monticola best suited for Pb remediation based on greater growth and tolerance in response to the low Pb treatment compared to the high Pb treatment. Salix monticola stems also contained higher Pb concentrations in control treatment compared to S. planifolia. We found S. planifolia and S. drummondiana best suited for Cd remediation. Salix drummondiana accumulated higher concentrations of Cd in stems than both S. monticola and S. planifolia. Salix planifolia accumulated nearly 2.5 times greater concentrations of Cd in stems in control treatment than did S. drummondiana. Salix planifolia also contained more total Cd in stems than did S. monticola in Cd treatments. Based on our results, S. drummondiana and S. planifolia could aid in reduction of Cd in watersheds, and S. monticola is better suited than is S. planifolia for aboveground accumulation and tolerance of Pb pollution.

Riparian Shrub Metal Concentrations and Growth in Amended Fluvial Mine Tailings

Fluvial mine tailing deposition has caused extensive riparian damage throughout the western USA. Willows are often used for fluvial mine tailing revegetation, but some accumulate excessive metal concentrations potentially detrimental to browsers. This greenhouse experiment evaluated growth and metal accumulation of Geyer willow (Salix geyeriana Andersson), Drummond’s willow (Salix drummondiana Barratt ex Hook.), diamondleaf willow (Salix planifolia Pursh), Bebb willow (Salix bebbiana Sarg.), thinleaf alder [Alnus incana (L.) Moench spp. tenuifolia (Nutt.) Breitung], water birch (Betula occidentalis Hook.), red-osier dogwood (Cornus sericea L. spp. sericea), and shrubby cinquefoil [(Dasiphora fruticosa (L.) Rydb. ssp. floribunda (Pursh) Kartesz)]. Bare-root shrubs were grown in tailings collected from three acidic, metal-contaminated (i.e., Cd, Cu, Pb, and Zn) fluvial deposits near Leadville, Colorado, USA. Tailings were amended with only lime to raise the soil pH to 7 s.u., or with lime and composted biosolids (224 Mg ha−1). All shrubs survived in the amended tailings; composted biosolids had little effect on plant biomass. Aboveground and belowground biomass increased during the 2-month greenhouse study by 3–9 and 1.5–5 times initial values, respectively. Most shrubs accumulated Pb and Cu in roots, and belowground Pb concentrations in all shrubs were significantly reduced by the addition of composted biosolids. Compared to other species, alder and cinquefoil accumulated Pb in aboveground growth, and concentrations exceeded animal toxicity thresholds, but these shrubs normally comprise a small proportion of animal diets. Dogwood, alder, and cinquefoil contained low Cd concentrations in aboveground new growth, whereas Bebb and Geyer willow contained zootoxic concentrations. Dogwood, alder, and cinquefoil are three good candidates for mine tailing revegetation, especially in fluvial deposits with elevated Cd concentrations.

Wild Ungulate Herbivory of Willow on Two National Forest Allotments in Wyoming

Abstract Willows (Salix) are important riparian plants and often used to indicate riparian condition. Many herbivores feed on willows, but there is limited information about willow browsing by wildlife except in national parks. This study was conducted to estimate wild ungulate herbivory of willow on two US Forest Service allotments in northern Wyoming and to compare these values to published estimates for national parks. We also compared total annual and seasonal willow utilization by wildlife between sites dominated by willows of different heights. The effects of height category, site, and season on willow utilization were determined with a repeated measures analysis. Four permanent willow utilization transects were established at each of six study sites per allotment on two allotments, in communities supporting planeleaf (Salix planifolia Pursh), Wolf's (Salix wolfii Bebb), Drummond's (Salix drummondiana Barratt ex Hook.), or Eastwood's (Salix eastwoodiae Cock. ex A. Heller) willow. Twenty-five twigs w...

Effect of browse on post-ingestive energy loss in an Arctic ruminant: implications for muskoxen (Ovibos moschatus) in relation to vegetation change

Shrubs are predicted to dominate tundra with warmer temperatures at northern latitudes. We tested the null hypothesis that addition of browse to a graminoid diet would not alter post-ingestive energy loss in muskoxen ( Ovibos moschatus (Zimmermann, 1780)). Energy losses over 8 h following feeding were used to test our hypothesis. Willows ( Salix alaxensis (Anderss.) Coville, Salix planifolia ssp. pulchra (Cham.) Argus) and birch ( Betula nana L.) (twigs in winter, leaves in summer) were separately mixed at graded levels (0%, 20%, 40%, 60%, and 80%) with chopped hay ( Bromus inermis Leyss.) and fed as single meals to muskoxen. Meals containing ≥60% browse were often partially or completely rejected. Meals containing 20%–60% woody or leafy S. alaxensis or S. p. pulchra resulted in higher energy expenditure than meals of 100% hay. Meals containing 20%–60% woody B. nana tended to decrease energy expenditure relative to 100% hay, while 20%–60% leafy B. nana was similar to 100% hay. We conclude there is an energy cost associated with consuming browse. This cost varies by browse species and type. Since muskoxen tolerated up to 40% browse in the diet, this cost may be within their ecological tolerance. This tolerance has important implications under global warming scenarios.

Resilience of Willow Stems After Release From Intense Elk Browsing

Abstract The resilience of willow ( Salix monticola Bebb, Salix geyeriana Anderss., Salix planifolia Pursh) stems released from intense elk ( Cervus elaphus ) browsing in Rocky Mountain National Park, Colorado, was quantified in 1998 with a retrospective study that compared biomass, number, and length of segments on willow stems located inside (protected) and outside (browsed) elk exclosures. Segment biomass increased each year after protection by about 3–12 g year −1 on browsed stems and 10–27 g year −1 on protected stems. The number of segments on stems was similar for browsed and protected stems in the first 2 years after exclusion but differed in the next 3 years, when they increased exponentially on protected stems. Nearly 80% of segments on browsed stems were

Clipping Frequency Affects Canopy Volume and Biomass Production in Planeleaf Willow (Salix planifolia var. planifolia Prush)

Willows (Salix) are often a key component of riparian ecosystems and are often browsed by both wildlife and livestock. However, little is understood about how the frequency of browsing affects aboveground and belowground willow production. The objectives of this study were to determine how the frequency of simulated browsing events in a controlled environment affected 1) the aboveground, belowground, and total biomass production and 2) the canopy volume of planeleaf willow (Salix planifolia var. planifolia Prush) plants. The experiment was a completely randomized block design consisting of 2 groups of willow plants with different clipping histories. Within each group, plants were randomly assigned to 1 of 11 subgroups. Clipping events comprised of all combinations of early, middle, and late season periods were imposed on the treatment subgroups, while 1 subgroup served as the control. Canopy volume measurements were made before and after each clipping event. Canopy volume change was related to the harvested twig length (cm) and weight (g). Results suggested that frequency of clipping alone did not explain differences in aboveground and belowground willow production. Instead, willow production was influenced by an accumulation of specific combinations of seasonal clipping events and was dependent on the clipping history of the plants. Early season clipping, alone or in combination with other events, was more detrimental to willows with prior clipping histories than middle or late season clipping treatments. Willow with prior clipping histories treated in either the middle or late seasons, and the late/middle combination produced more than the controls. These results should be verified in willow communities subjected to natural environmental variations and browsing.

Clipping Frequency Affects Canopy Volume and Biomass Production in Planeleaf Willow (Salix planifolia var. planifolia Prush)

Willows (Salix) are often a key component of riparian ecosystems and are often browsed by both wildlife and livestock. However, little is understood about how the frequency of browsing affects aboveground and belowground willow production. The objectives of this study were to determine how the frequency of simulated browsing events in a controlled environment affected 1) the aboveground, belowground, and total biomass production and 2) the canopy volume of planeleaf willow (Salix planifolia var. planifolia Prush) plants. The experiment was a completely randomized block design consisting of 2 groups of willow plants with different clipping histories. Within each group, plants were randomly assigned to 1 of 11 subgroups. Clipping events comprised of all combinations of early, middle, and late season periods were imposed on the treatment subgroups, while 1 subgroup served as the control. Canopy volume measurements were made before and after each clipping event. Canopy volume change was related to the harvested twig length (cm) and weight (g). Results suggested that frequency of clipping alone did not explain differences in aboveground and belowground willow production. Instead, willow production was influenced by an accumulation of specific combinations of seasonal clipping events and was dependent on the clipping history of the plants. Early season clipping, alone or in combination with other events, was more detrimental to willows with prior clipping histories than middle or late season clipping treatments. Willow with prior clipping histories treated in either the middle or late seasons, and the late/middle combination produced more than the controls. These results should be verified in willow communities subjected to natural environmental variations and browsing.

Resilience of Willow Stems After Release From Intense Elk Browsing

The resilience of willow (Salix monticola Bebb, Salix geyeriana Anderss., Salix planifolia Pursh) stems released from intense elk (Cervus elaphus) browsing in Rocky Mountain National Park, Colorado, was quantified in 1998 with a retrospective study that compared biomass, number, and length of segments on willow stems located inside (protected) and outside (browsed) elk exclosures. Segment biomass increased each year after protection by about 3-12 g year-1 on browsed stems and 10-27 g year-1 on protected stems. The number of segments on stems was similar for browsed and protected stems in the first 2 years after exclusion but differed in the next 3 years, when they increased exponentially on protected stems. Nearly 80% of segments on browsed stems were &lt; 5 cm in length in 1994-1997, which caused stems to develop a short-hedged morphology. Protected stems had more long segments and fewer short segments than browsed stems for the first 3 years, but then increased their number of short segments as stems became tall and bushy. Thus, evidence suggests short-hedged willow stems are highly resilient and can rapidly recover height and vigor after protection from intense elk browsing.

Leaf thickness ofSalixspp. (Salicaceae) from the Athabasca sand dunes of northern Saskatchewan, Canada

Leaf thicknesses of Salix taxa (Salix brachycarpa Nutt. var. psammophila Raup, Salix planifolia Pursh subsp. tyrrellii (Raup) Argus, Salix silicicola Raup, and Salix turnorii Raup) from the Athabasca sand dunes in northern Saskatchewan, Canada, were evaluated and compared with those of their respective widespread progenitors (S. brachycarpa Nutt. var. brachycarpa, S. planifolia Pursh subsp. planifolia, Salix alaxensis (Anders.), and Salix eriocephala Michx. var. famelica (C. R. Ball) Dorn). Leaf thickness was measured using standard light microscopy, and results were compared with the occurrence of amphistomaty in these Salix species. Leaf thickness values varied among the species and differed significantly within each derivative–progenitor Salix pair. The two amphistomatic taxa from Yakow Lake dunes, S. turnorii and S. planifolia subsp. tyrrellii, had significantly thicker leaves (337.65 ± 5.99 µm and 226.00 ± 5.22 µm, respectively) than their widespread progenitors, as well as the thickest leaves overall. The data comparison indicates a relationship between amphistomaty and leaf thickness among the Salix taxa, as thicker leaves tend to be amphistomatic.Key words: amphistomaty, Athabasca sand dunes, leaf thickness, Salix, willow.

A comparative epidermis study of the Athabasca sand dune willows (Salix; Salicaceae) and their putative progenitors

The Athabasca sand dunes are located on the south shore of Lake Athabasca in northern Alberta and Saskatchewan, Canada. Four willow shrubs (Salix; Salicaceae) occur on the open sands, two of which are endemic to the Athabasca sand dunes. Light and scanning electron microscopy were used to quantify stomatal frequency, stomatal index, trichome density, and cuticle thickness, for the Athabasca sand dune willows and their associated putative progenitors. The Athabasca sand dune taxa (Salix brachycarpa var. psammophila, Salix planifolia subsp. tyrrellii, Salix silicicola, and Salix turnorii) occur primarily on the inner dunes, and each has certain leaf epidermal features that appear to be adaptive to the exposed nature of the open sand habitat and the high light intensity. Salix brachycarpa var. psammophila and S. silicicola have tomentose leaves, with trichome densities that are significantly greater than those of their respective widespread progenitors. Salix planifolia subsp. tyrrellii and S. turnorii have amphistomatic leaves and substantially thicker cuticles than their associated progenitors. This investigation is the first to compare adaptive leaf epidermis features within the derivative–progenitor Salix pairs. Considerations for the significance of amphistomaty in the Athabasca sand dune Salix taxa are discussed.Key words: Athabasca sand dunes, cuticle, Salix, stomata, trichomes, willow.

Succession of microfungal assemblages in decomposing peatland plants

We investigated the microfungal assemblages in the decomposing tissues of dominant plant species in two peatlands in southern boreal Alberta, Canada, to determine if distinct patterns of succession of microfungi occurred throughout the first two years of decomposition. These plant species were Sphagnum fuscum from a bog and Carex aquatilis leaves and rhizomes and Salix planifolia leaves and roots from a riverine, sedge-dominated fen. Canonical correspondence analyses, a multivariate statistical analysis used infrequently in mycological research, revealed distinct patterns of fungal species succession in two of the five litters (S. fuscum and C. aquatilis leaves). Furthermore, our analyses showed that substantially different microfungal assemblages were associated with these litters within the first two years of decomposition. Litter quality variables, such as total nitrogen, total phosphorus, and total carbon tissue nutrient concentrations, explained most of the succession patterns and differences in the microfungal assemblages of these five litters. Our data did not reveal the classical taxonomic zygomycete – ascomycete/fungi imperfecti – basidiomycete pattern of succession during organic matter decomposition. Similarly, a succession of functional groups of microfungi, i.e., cellulose-degraders preceding lignin-degraders, generally was not apparent. Instead, microfungi with broad spectra of enzymatic abilities co-existed over the first two years of decomposition in these peatland plant litters. These microfungi have a limited ability to decompose complex phenolic polymers, such as lignin, resulting in the accumulation of peat in these ecosystems. Some microfungal taxa were not affected by changes in litter quality, environmental variables, or surface water chemistry and were present at all stages of decomposition.

Evaluation of a Technique for Measuring Canopy Volume of Shrubs

Cover methods quantify vegetative communities in only 2 dimensions. The addition of height measurements to cover data, resulting in canopy volume estimates, provide a more practical level of description for shrub communities. We evaluated a technique to estimate canopy volume of shrubs that used a formula [2/3piH (A/2 x B/2)] derived from the basic ellipsoid volume formula. Objectives of this study were to determine if there were significant differences among means of repeated observations on sample units: (1) among observers; (2) within observers; and (3) between sample periods when using this technique. At 2 locations in Wyoming, 10 planeleaf willow (Salix planifolia var. planifolia Pursh) plants along each of 5 randomly established transects were sampled during 2 consecutive periods by 4 observers. Differences among observers were significant at both sites (P 0.05) at either site. Mean canopy volume did not vary significantly (P > 0.05) between sample periods when averaged across observers. Estimated sample sizes ranged between 2 and 31 transects depending on the desired sampling precision and confidence level. The average time per transect among all observers decreased from 13 minutes (SD = 3.7) in sample period 1 to 9 minutes (SD = 1.3) in sample period 2. Using this method, managers can better describe and monitor trends in the structural diversity of shrub communities. This canopy volume technique can be applied with minimal training and is precise, efficient, and repeatable. DOI:10.2458/azu_jrm_v55i3_thorne

Evaluation of a technique for measuring canopy volume of shrubs

Cover methods quantify vegetative communities in only 2 dimensions. The addition of height measurements to cover data, resulting in canopy volume estimates, provide a more practical level of description for shrub communities. We evaluated a technique to estimate canopy volume of shrubs that used a formula [2/3piH (A/2 x B/2)] derived from the basic ellipsoid volume formula. Objectives of this study were to determine if there were significant differences among means of repeated observations on sample units: (1) among observers; (2) within observers; and (3) between sample periods when using this technique. At 2 locations in Wyoming, 10 planeleaf willow (Salix planifolia var. planifolia Pursh) plants along each of 5 randomly established transects were sampled during 2 consecutive periods by 4 observers. Differences among observers were significant at both sites (P &lt; 0.05). However, within observer variation between sample periods was not significant (P &gt; 0.05) at either site. Mean canopy volume did not vary significantly (P &gt; 0.05) between sample periods when averaged across observers. Estimated sample sizes ranged between 2 and 31 transects depending on the desired sampling precision and confidence level. The average time per transect among all observers decreased from 13 minutes (SD = 3.7) in sample period 1 to 9 minutes (SD = 1.3) in sample period 2. Using this method, managers can better describe and monitor trends in the structural diversity of shrub communities. This canopy volume technique can be applied with minimal training and is precise, efficient, and repeatable.

Armillaria sinapina in herbaceous plant material from a peatland in Alberta, Canada

Armillaria sinapina Bérubé &amp; Dessureault mycelium was isolated once from living Carex aquatilis Wahlenb. rhizomes, twice from decomposing C. aquatilis leaves, and three times from decomposing Salix planifolia Pursh leaves in a southern boreal sedge-dominated fen in Alberta, Canada. Restriction fragment length polymorphism (RFLP) analyses of the IGS-1 region with the AluI restriction enzyme were used to identify the isolates, because conspicuous, epigeous basidiomes could not be found in or near the fen. During these analyses, two previously unpublished fragment patterns for A. sinapina were found, consisting of 399–240–135 base pairs (bp) and 399–240–183–135 bp. Interspecific somatic incompatibility and interfertility tests confirmed the identifications obtained from the RFLP analyses. This is the first report of an annulate species of Armillaria being actively involved in the colonization and decomposition of herbaceous plant material in an ecosystem having only an organic soil horizon. Surveys for species of Armillaria should be expanded to include peatlands and herbaceous plant materials, because they may serve as vast potential biomass and genetic diversity reservoirs for this genus.Key words: peatland, Carex rhizomes, Salix leaves, RFLP, interspecific somatic incompatibility, interfertility.