Terrestrial Lichens Research Articles

Germination Ecology ofLiatris ohlingerae(S.F. Blake) B.L. Rob. (Asteraceae), an Endangered Herb Endemic to Florida Scrub

Seed source, absence of favorable microhabitat conditions, and presence of competitors, predators or allelochemicals are among the many factors that may limit the germination of viable seeds. We conducted six field, growth chamber, and veranda experiments to investigate the effects of seed source, physical or chemical presence of co-occurring species, and litter presence on germination percentages of the Florida scrub endemic Liatris ohlingerae. This perennial herb produces many seeds but recruits few seedlings. Germination percentages were similar when seeds from scrub and roadside habitats were sown into their own and the contrasting habitat. We found no evidence of chemical inhibition from a co-occurring terrestrial lichen or from the allelopathic Florida rosemary (Ceratiola ericoides), the dominant shrub in the habitat preferred by L. ohlingerae. However, germination was higher in shallow than in deep litter, and was suppressed by litter from oaks and pines compared to litter from Florida rosemary. In one experiment, higher levels of post-sowing seed predation closer to Florida rosemary shrubs limited germination. Germination of intact L. ohlingerae seeds generally exceeded 60% under a range of field and lab conditions. High field germination percentages within a few weeks of sowing suggest that L. ohlingerae does not maintain a sizeable persistent seed bank. Low seedling recruitment in this endangered plant is not likely caused by poor seed germination.

Species Diversity and Genetic Variation of Terrestrial Lichens and Bryophytes in A Boreal Jack Pine Forest of Central Canada

Little is known about species diversity and genetic structure of populations of lichens and bryophytes in the Sandilands Provincial Forest in Manitoba. This study investigated the current species diversity of lichens and bryophytes in the area. It also examined the population structure and gene flow in the lichen (Cladonia arbuscula) with the highest cover and second most frequent occurrence, and bryophyte (Pleurozium schreberi) with the highest frequency and percent ground cover. Analysis of Molecular Variance (AMOVA) of the presence and absence of group I introns in the fungal small subunit (SSU) nuclear ribosomal DNA (rDNA) and Restriction Fragment Length Polymorphisms (RFLP) of the algal Internal Transcribed Spacer (ITS) rDNA suggests that low levels of gene flow were occurring in the fungus while a single algal genotype was maintaining the lichen association. Similarly, Interspersed Simple Sequence Repeat (ISSR) markers of the bryophyte suggested low levels of gene flow. The examination of variation in both lichen symbionts and a bryophyte, dominant within the same habitat, is a novel aspect of this study. Both these widespread species, dominating the understory in mature jack pine forests, exhibited low levels of sexual reproduction.

Demographic and behavioural response of woodland caribou to forest harvesting

We investigated whether woodland caribou ( Rangifer tarandus caribou ) would remain in a 2772 km2 area in eastern Quebec where the forest management plan included the preservation of large forest blocks (35–182 km2) linked with >400 m wide corridors and where cuts were amalgamated in large zones. To evaluate changes in caribou abundance and habitat selection, we conducted five aerial surveys and followed by telemetry 13 to 22 female caribou each year, from March 1998 to March 2005. Caribou numbers declined by 59% between 1999 and 2001 but gradually recovered to initial abundance. Female survival increased from 73.3% in 1999 to 87.3%–93.4% in 2004 and 2005. Caribou selected protected blocks, used corridors in proportion to their availability, and avoided logged areas. They preferred closed conifer stands without terrestrial lichens and open conifer stands with or without terrestrial lichens throughout the study. Open habitats (clearcuts and burns), regenerating sites, mixed and deciduous stands, and water bodies were avoided. The main zones used by caribou gradually shifted towards the southwest of the study area, likely as a result of disturbance and habitat loss due to logging of mature conifers in the east. We conclude that caribou numbers were maintained within the managed area as a result of the presence of protected blocks and uncut continuous forest.

Effects of forest disturbance on density, space use, and mortality of woodland caribou

Woodland caribou (Rangifer tarandus caribou), a threatened species in Canada, inhabit landscapes dominated by mature and over-mature coniferous stands and tend to avoid areas used by other cervids, wolves (Canis lupus), and humans. We hypothesized that habitat modifications through logging and forest fire alter the space-use pattern of woodland caribou and result ultimately in lowered density. To test this hypothesis, density, distribution, space-use patterns, and mortality of caribou in disturbed landscapes (DLs) and undisturbed landscapes (ULs) of central Québec were quantified by a systematic aerial survey (42 539 km2) and telemetry of 68 adult caribou females. A ground survey of terrestrial and arboreal lichens was carried out to estimate production of lichens in DLs and ULs. Three populations that occupied between 10 000 and 15 000 km2 were identified in the study area. Caribou abundance was not limited by intraspecific competition for food. Production of terrestrial lichens was estimated to support 3 to 4 times the surveyed caribou density (1.2–2.1–100 km−2). Pregnancy rate was almost 100%, indicating that females were not food-limited. Space-use patterns were affected by forest disturbance. In DLs, caribou increased home range sizes and reduced fidelity to seasonal and annual home ranges, probably to avoid disturbed habitats. In response, the probability of surviving decreased with the extent of DL within home ranges. To help keep direct and indirect sources of caribou mortality at very low levels, forest management strategies should be oriented toward the protection of large interconnected blocks of forest to favour caribou spacing away from humans and predators and to maintain adequate space-use strategies.

Water relations and carbon dioxide exchange of epiphytic lichens in the Namib fog desert

Although there is only negligible rainfall, frequent nocturnal fog, dew and high air humidity support a luxurious lichen vegetation in the coastal zone of the central Namib Desert (Namibia). In earlier publications, we have studied ecophysiological performance of a series of epilithic and terrestrial lichens. Here, we have extended this work to three epiphytic species ( Heterodermia namaquana, Ramalina lacera, and Xanthoria turbinata) that inhabit the sparse perennial shrubs growing in this area. Our intention, monitoring lichen CO 2 exchange, their water relations and microclimate conditions, was to determine the functional mechanisms that allow these epiphytes to exist under the special conditions of a fog desert. Measurements were conducted mainly during the spring season. The epiphytic lichens showed response patterns very similar to the epilithic and epigaeic species at the same site. Their metabolism was activated through moistening by dew and/or fog during the night and, in the very early morning, they exhibited the typical brief peak of net photosynthesis (NP) between sunrise and desiccation. The thalli were almost completely dry for the remainder of the day. Average duration of the positive NP during the morning peak was about 3 h. Dew condensation, alone, resulted in activation that provided 58–63% of integrated carbon income (ΣNP) as compared to fog (plus dew). In the late afternoon, there was a tendency for hydration to increase again, due to water vapour uptake at higher air humidity, and this allowed on some days a brief additional period of very low rates of photosynthesis shortly before sunset. Light response of photosynthesis showed “sun-plant” characteristics with saturation around 1000 μmol m −2 s −1 photosynthetically active photon flux density (PPFD). Light compensation point (LCP) of CO 2 exchange after sunrise was highly dependent on actual water content (WC) for X. turbinata: at low hydration it was ca. 10 μmol m −2 s −1 PPFD whilst, at high WC, it was almost 80 μmol m −2 s −1 PPFD. In contrast, LCP of R. lacera was almost independent of WC. This phenomenon was probably due to differences in thallus structure. Maximal attained NP and daily ΣNP both showed a saturation-type response to previous maximal nocturnal WC. Neither parameter was increased substantially when higher maximal thallus WCs were produced by experimental moistening in the night. All three species, despite their different morphologies, performed optimally at the highest nocturnal moistening achieved by natural fog and were not able to make use of higher hydration. The three studied epiphytes were similar in their chlorophyll-related rates of NP. Due to lower chlorophyll content, dry weight and carbon-related NP of X. turbinata was only about one-third of that of the other two species. The average carbon income on days with fog and/or dew hydration during the spring season amounted to 2.4 and 2.1 mgC (gC) −1 day −1 (related to thallus carbon content) for H. namaquana and R. lacera, respectively. This primary production was of similar magnitude to those found for the terrestrial species at the same site.

Woodland caribou persistence and extirpation in relic populations on Lake Superior

Extended: The hypothesis was proposed that woodland caribou (Rangifer tarandus caribou) in North America had declined due to wolf predation and over-hunting rather than from a shortage of winter lichens (Bergerud, 1974). In 1974, two study areas were selected for testing: for the lichen hypothesis, we selected the Slate Islands in Lake Superior (36 km2), a closed canopy forest without terrestrial lichens, wolves, bears, or moose; for the predation hypothesis, we selected the nearby Pukaskwa National Park (PNP) where terrestrial lichens, wolves, bears, and moose were present. Both areas were monitored from 1974 to 2003 (30 years). The living and dead caribou on the Slates were estimated by the ‘King census’ strip transect (mean length 108±9.3 km, extremes 22-190, total 3026 km) and the Lincoln Index (mean tagged 45±3.6, extremes 15-78). The mean annual population on the Slate Islands based on the strip transects was 262±22 animals (extremes 104-606), or 7.3/km2 (29 years) and from the Lincoln Index 303±64 (extremes 181-482), or 8.4/km2 (23 years). These are the highest densities in North America and have persisted at least since 1949 (56 years). Mountain maple (Acer spicatum) interacted with caribou density creating a record in its age structure which corroborates persistence at relatively high density from c. 1930. The mean percentage of calves was 14.8±0.34% (20 years) in the fall and 14.1±1.95% (19 years) in late winter. The Slate Islands herd was regulated by the density dependent abundance of summer green foods and fall physical condition rather than density independent arboreal lichen availability and snow depths. Two wolves (1 wolf/150 caribou) crossed to the islands in 1993-94 and reduced two calf cohorts (3 and 4.9 per cent calves) while female adult survival declined from a mean of 82% to 71% and the population declined ≈100 animals. In PNP, caribou/moose/wolf populations were estimated by aerial surveys (in some years assisted by telemetry). The caribou population estimates ranged from 31 in 1979 to 9 in 2003 (Y=1267 - 0.628X, r=-0.783, n=21, P<0.01) and extirpation is forecast in 2018. Animals lived within 3 km of Lake Superior (Bergerud, 1985) with an original density of 0.06/km2, similar to many other woodland herds coexisting with wolves (Bergerud, 1992), and 100 times less than the density found on the Slate Islands. The mean moose population was 0.25±0.016/km2 and the wolf population averaged 8.5±0.65/1000 km2. Late winter calf percentages in PNP averaged 16.2±1.89 (25 years); the population was gradually reduced by winter wolf predation (Bergerud, 1989; 1996). The refuge habitat available is apparently insufficient for persistence in an area where the continuous distribution of woodland caribou is fragmented due to moose exceeding 0.10/km2 and thereby supporting wolf densities ≥6.5/1000 km2. A second experimental study was to introduce Slate Island caribou to areas with and without wolves. A release to Bowman Island, where wolves and moose were present, failed due to predation. Bowman Island is adjacent to St. Ignace Island where caribou had persisted into the late 1940s. A second release in 1989 to the mainland in Lake Superior Provincial Park of 39 animals has persisted (<10 animals) because the animals utilize off-shore islands but numbers are also declining. A third release to Montréal Island in 1984 doubled in numbers (up to 20 animals) until Lake Superior froze in 1994 and wolves reached the island. A fourth release was to Michipicoten Island (188 km2) in 1982 where wolves were absent and few lichens were available. This herd increased at λ= 1.18 (8 to ±200, 160 seen 2001) in 19 years. This was the island envisioned for the crucial test of the lichen/predation hypotheses (Bergerud, 1974: p.769). These studies strongly support the idea that ecosystems without predators are limited bottom–up by food and those with wolves top-down by predation; however the proposed crucial test which has been initiated on Michipicoten Island remains to be completed and there is a limited window of opportunity for unequivocal results.

Pinastric acid revisited: a complete NMR and X-ray structure assignment

Chemical investigation of a terrestrial lichen has yielded the pulvinic acid derivative pinastric acid (4). The structure of 4 was secured by detailed spectroscopic analysis as well as via a single X-ray diffraction study. This is the first report of the X-ray structure and 2D NMR assignment of pinastric acid (4). Pinastric acid (4) displayed antitumour, antiviral and antimicrobial (both antibacterial and antifungal) activities. Whilst the antiviral and antimicrobial activities are consistent with previous findings of 4 this is the first report of the antitumour properties for the compound.

Using Bayesian belief networks in adaptive management

Bayesian belief and decision networks are modelling techniques that are well suited to adaptive-management applications, but they appear not to have been widely used in adaptive management to date. Bayesian belief networks (BBNs) can serve many purposes, from illustrating a conceptual understanding of system relations to calculating joint probabilities for decision options and predicting outcomes of management policies. We describe the nature and capabilities of BBNs, discuss their applications to the adaptive-management process, and present a case example of adaptive management of forests and terrestrial lichens in north-central British Columbia. We recommend that those unfamiliar with BBNs should begin by first developing influence diagrams with relatively simple structures that represent the system under management. Such basic models can then be elaborated to include more variables, the mathematical relations among them, and features that allow assessment of the utility of alternative management actions or strategies. Users of BBNs should be aware of several important limitations, including problems in representing feedback and time–dynamic functions. Nevertheless, when properly used, Bayesian networks can benefit most adaptive-management teams by promoting a shared understanding of the system being managed and encouraging the rigorous examination of alternative management policies.

SIMULATING THE INFLUENCES OF VARIOUS FIRE REGIMES ON CARIBOU WINTER HABITAT

Caribou are an integral component of high-latitude ecosystems and represent a major subsistence food source for many northern people. The availability and quality of winter habitat is critical to sustain these caribou populations. Caribou commonly use older spruce woodlands with adequate terrestrial lichen, a preferred winter forage, in the understory. Changes in climate and fire regime pose a significant threat to the long-term sustainability of this important winter habitat. Computer simulations performed with a spatially explicit vegetation succession model (ALFRESCO) indicate that changes in the frequency and extent of fire in interior Alaska may substantially impact the abundance and quality of winter habitat for caribou. We modeled four different fire scenarios and tracked the frequency, extent, and spatial distribution of the simulated fires and associated changes to vegetation composition and distribution. Our results suggest that shorter fire frequencies (i.e., less time between recurring fires) on the winter range of the Nelchina caribou herd in eastern interior Alaska will result in large decreases of available winter habitat, relative to that currently available, in both the short and long term. A 30% shortening of the fire frequency resulted in a 3.5-fold increase in the area burned annually and an associated 41% decrease in the amount of spruce-lichen forest found on the landscape. More importantly, simulations with more frequent fires produced a relatively immature forest age structure, compared to that which currently exists, with few stands older than 100 years. This age structure is at the lower limits of stand age classes preferred by caribou from the Nelchina herd. Projected changes in fire regime due to climate warming and/or additional prescribed burning could substantially alter the winter habitat of caribou in interior Alaska and lead to changes in winter range use and/or population dynamics.

Water relations and CO 2 exchange of the terrestrial lichen Teloschistes capensis in the Namib fog desert: Measurements during two seasons in the field and under controlled conditions

Although the coastal zone of the Central Namib Desert (Namibia) has negligible rainfall, frequent fog, dew and high air humidity support a luxurious lichen flora. Large areas of soil crust communities are dominated by the multibranched, fruticose Teloschistes capensis interspersed by a (still indeterminable) Ramalina species. In earlier communications, based on field measurements in autumn, we began the analysis of functional mechanisms that allow these lichens to exist under the special conditions of a fog desert. We have extended this work by monitoring lichen CO 2 exchange and water relations in spring and by experiments under controlled conditions. In both seasons, nocturnal hydration, by fog and/or dew, activated dark respiration of the lichens which was followed, after sunrise, by a short period of positive net photosynthesis (NP) that continued until metabolic inactivation occurred from desiccation. Dry thalli of T. capensis were able to reactivate NP through water vapour uptake alone, beginning at an air relative humidity of 82%, i.e. at a water potential of −26.3 MPa; the moisture compensation point during desiccation was at 13% thallus water content (WC, dry weight related). Optimal WC for photosynthesis was around 100%, and both species showed a large and extended suprasaturation depression of CO 2 assimilation. Light response showed “sun-plant” characteristics with saturation >1000 μmol m −2 s −1 photosynthetically active photon flux density (PPFD). However, due to rapid desiccation, the combination of light saturation with optimal WC very rarely occurred under field conditions. Light compensation point after sunrise was highly dependent on actual WC: at low hydration, it amounted to only ca. 10 μmol m −2 s −1 PPFD so that even the smallest levels of hydration could be used for carbon gain before desiccation took place again. This phenomenon was probably due to a hydration gradient in the thallus branches during transient moistening so that the outer photobiont layer was favoured in contrast to the internal mycobiont which remained dry longer and did not contribute respiratory CO 2 loss. Fully hydrated thalli had light compensation points around 50 μmol m −2 s −1 PPFD. Extended desiccation of 1–3 days had no impact on the magnitude and recovery of photosynthesis but, imposed desiccation of 10 days reduced NP in lab and field experiments and caused an extended period of recovery. “Resaturation respiration” was not detected in the field data, although it was present after experimental moistening of dry thalli. In spring, the higher fog frequency and intensity increased maximal nocturnal WC, maximal attained NP as well as integrated daily carbon income (ΣNP) compared to the autumn measurements. NP max and ΣNP depended on maximal nocturnal WC with a saturation-type response. In terms of carbon gain both species seem to be optimally adapted to nocturnal moistening up to 160% WC and were not able to make use of higher degrees of hydration, a feature that might well influence their habitat selection. Maximal daily carbon-related ΣNP for T. capensis was 4.6 mg C (g C) −1 day −1. A rough estimate of the annual (projected) area-related carbon balance (photosynthetic income minus respiratory losses) based on published fog and dew frequencies and personal observations was 15–34 mg C m −2 yr −1.

Contrasting terrestrial lichen, liverwort, and moss diversity between old-growth and young second-growth forest on two soil textures in central British Columbia

The diversity and abundance of terrestrial lichens, mosses, and liverworts were examined and compared between two ages of forest (old-growth and young second-growth) on two dominant soil types (fine- and coarse-textured soils) in subboreal spruce forests in central British Columbia. Major differences in species composition were found between forest ages, with 30% of species found only in old-growth forest and 21% found only in young second-growth forest. Liverworts were much more common in old-growth sites with half the liverwort species found exclusively in old-growth, and 90% of the recorded liverwort observations occurring there. Different moss species assemblages dominated old-growth and second-growth sites, with much of the terrestrial cover of second-growth sites composed of Polytrichum juniperinum Hedw. Young second-growth forest had higher cover of lichen species than old-growth forest. Lichens and bryophytes used different terrestrial substrates in each forest age, with higher cover of mosses and lichens occurring on woody substrates in old-growth, irrespective of substrate availability. Nonmetric multidimensional scaling ordination clearly separated plots by forest age and also showed soil texture to be a defining variable. Though not statistically significant, there was increased bryophyte diversity on coarse-textured soils and increased lichen cover on fine-textured soils.

Lichen abundance in the peatlands of northern Alberta: Implications for boreal caribou

:In boreal forests, wildfire is a dominant ecological process that, among other things, affects the distribution and abundance of terrestrial lichens. Woodland caribou (Rangifer tarandus caribou) occupying peatland complexes of western Canada rely on terrestrial lichens for winter forage. Understanding the relationship between lichen distribution and fire is therefore important in order to understand caribou ecology. We documented abundance of terrestrial lichens in 73 peatland sites in northern Alberta, all within caribou home ranges. Forty-eight of these had been disturbed by forest fire within the past 70 y, while 25 had not been disturbed for at least 70 y. Peatlands that had not been disturbed for at least 70 y had low lichen cover (average 21.7± 2.1%; range 4.6–54.0%) and lower lichen biomass (660.0± 63.3 kg·ha-1) than other studied boreal areas. However, lichen in sites disturbed by fire appeared to have recovered after only 40 y. This rapid recovery seems to have been mediated by a high growth rate: 4.8± 0.1 mm·y-1. Controlling for the effect of time since fire, lichen cover was inversely related to cover of Sphagnum spp., while growth rates of lichen were positively related to time since fire. Although the re-growth of lichen after fire was rapid in comparison to other systems, we suggest that fire has a strong effect on lichen distribution and hence on the spatial distribution of foraging habitat for Alberta caribou.

Seedling response following partial cutting in lodgepole pine forests on caribou winter range in west-central British Columbia

Group selection and irregular group shelterwood silvicultural systems were applied to older lodgepole pine (Pinus contorta var. latifolia) forests in west-central British Columbia to determine their potential for maintaining northern caribou (Rangifer tarandus caribou) habitat. These silvicultural systems created small openings 15–30 m wide,which were planted with lodgepole pine and interior spruce (Picea glauca x Picea engelmannii) seedlings. Fifth-year survival and growth results indicate that either species could adequately regenerate the small openings created by partial cutting. Pine survival in the partial cuts (93–95%) was comparable to the clearcuts (94%). Pine height and height growth did not vary significantly between treatments; however, diameters were significantly larger in the clearcuts. After five years across all treatments, pine seedlings were 38–42 cm tall with diameters ranging from 7–11 mm. Spruce survival varied considerably between the clearcuts (35–98%) but was more consistent in the partial cuts (66–97%). Total height and height growth differed significantly among treatments, with the shortest spruce seedlings found in the clearcuts. Seedling diameter did not differ among treatments. Average fifth-year height ranged from 31 cm to 44 cm and diameters ranged from 7 mm to 9 mm. To maintain caribou habitat, species should be planted in similar proportions to the pre-harvest stand composition to avoid potential impacts on the terrestrial and arboreal lichens, which are important caribou forage. Key words: caribou, lodgepole pine, partial cutting, planted seedlings, interior spruce, group selection, irregular group shelterwood

Mountain pine beetles and emerging issues in the management of woodland caribou in Westcentral British Columbia

The Tweedsmuir—Entiako caribou (Rangifer tarandus caribou) herd summers in mountainous terrain in the North Tweedsmuir Park area and winters mainly in low elevation forests in the Entiako area of Westcentral British Columbia. During winter, caribou select mature lodgepole pine (Pinus contorta) forests on poor sites and forage primarily by cratering through snow to obtain terrestrial lichens. These forests are subject to frequent large-scale natural disturbance by fire and forest insects. Fire suppression has been effective in reducing large-scale fires in the Entiako area for the last 40—50 years, resulting in a landscape consisting primarily of older lodgepole pine forests, which are susceptible to mountain pine beetle (Dendroctonus ponderosae) attack. In 1994, mountain pine beetles were detected in northern Tweedsmuir Park and adjacent managed forests. To date, mountain pine beetles have attacked several hundred thousand hectares of caribou summer and winter range in the vicinity of Tweedsmuir Park, and Entiako Park and Protected Area. Because an attack of this scale is unprecedented on woodland caribou ranges, there is no information available on the effects of mountain pine beetles on caribou movements, habitat use or terrestrial forage lichen abundance. Implications of the mountain pine beetle epidemic to the Tweedsmuir—Entiako woodland caribou population include effects on terrestrial lichen abundance, effects on caribou movement (reduced snow interception, blowdown), and increased forest harvesting outside protected areas for mountain pine beetle salvage. In 2001 we initiated a study to investigate the effects of mountain pine beetles and forest harvesting on terrestrial caribou forage lichens. Preliminary results suggest that the abundance of Cladina spp. has decreased with a corresponding increase in kinnikinnick (Arctostaphylos uva-ursi) and other herbaceous plants. Additional studies are required to determine caribou movement and habitat use responses to the mountain pine beetle epidemic.

Movements, foraging habits, and habitat use strategies of northern woodland caribou during winter: Implications for forest practices in British Columbia

Land managers face increasing challenges as they try to balance timber harvesting with the habitat requirements of wildlife, including those of woodland caribou in north-central British Columbia. With the aim of conserving caribou by improving forest practices, we employed a hierarchical, scale-explicit approach to study the processes governing movement and distribution of the northern woodland caribou ecotype. Investigations of foraging sites north of Prince George, British Columbia revealed that caribou in forested and alpine areas cratered at locations with relatively low snow depths and relatively large amounts of terrestrial lichens. When snow depth, snow hardness, and snow density increased, caribou fed more frequently at trees supporting abundant arboreal lichens. Feeding activities of caribou in forested foraging patches were positively related to the biomass of several terrestrial lichen species and to decreasing snow depth; the number of arboreal feeding sites increased as snow depth and hardness increased. We identified three scales of habitat selection based on movement rates of caribou fitted with GPS collars. For all scales, caribou selected pine-lichen woodland and windswept rocky slopes. Predation risk was greatest for caribou travelling between habitat patches, was lowest for caribou in alpine habitats, and had no apparent influence on intra-patch movements.Land use plans should address the needs of northern woodland caribou by ensuring that large patches of widely distributed pine-lichen woodland are maintained on the landscape, recognize the limiting effects of deep snow (i.e., > 50–80 cm), and encourage silvicultural strategies that minimize the creation of early seral-stage forests adjacent to caribou movement routes.

Collembola succession on deposits from a chemical factory

Summary Primary succession of collembolan communities was studied on deposits of a former factory producing nitric, sulphuric, and muratic acids and soda at Petrovice u Karvine, NE Moravia, Czech Republic, in 1978–1979. Chemically loaded deposits were 15, 25 and 60 years old in 1979 and a primary succession without plant re-cultivation took place there. The succession was delayed on small humps and slopes where the deposited substrate was covered by terrestrial algae, lichens and mosses. A total of 4871 specimens of Collembola containing 78 species from 23 sampling sites were evaluated. The quantitative species data were analysed using TWINSPAN and CANOCO programs. Coenotic similarity was determined with a polythetic classification produced by two-way indicator species analysis performed for log ( n +1) transformed quantitative data. Collembolan communities were composed of 3–23 species in densities from 1300 to 80,700 ind·m 2 . Lower species number (3–9) in low densities and low diversity occurred on sites with the initial stages of succession covered with algae, lichens and mosses. Collembolan species typical of early succession included Mesaphorura atlantica , Hypogastrura assimilis , Schoettella ununguiculata and Doutnacia xerophila . The succession on two different deposit substrates converged in more advanced stages to a collembolan community including Mesaphorura hylophila , Parisotoma notabilis , Lepidocyrtus lanuginosus , Folsomia quadrioculata and F. lawrencei as typical species. Species such as Isotomiella minor , Megalothorax minimus and Friesea mirabilis entered the succession only in the most advanced stage of the 60 years old deposit. The absence of F. mirabilis was probably connected with the missing aquatic soil microfauna (Nematoda, Tardigrada, Rotatoria) in the chemically unfavourable substrates of the less advanced succession stages.

Growth performance of Cladina stellaris following caribou disturbance in subarctic Quebec

:Cladina stellaris is a dominant lichen species of old-growth lichen-spruce woodlands in subarctic Québec, where the continuous lichen carpet persists for several decades in the absence of disturbance. The lichen carpet is, however, vulnerable to caribou (Rangifer tarandus) disturbance under dry site conditions. Through grazing and trampling, large herds of migratory caribou reduce C. stellaris abundance and modify ground vegetation composition. Here, we have evaluated the age and growth performance of C. stellaris in relation to the recent activity of the George River Caribou Herd (GRCH). We measured the age, length, and growth rate of C. stellaris podetia in and near caribou trails in 15 lichen-spruce woodlands across the summer habitat. The age of lichens, used to evaluate the initial period of lichen recruitment following the decline of the GRCH, indicated that lichen recovery began in the early 1990s in heavily disturbed sites, whereas comparisons between the age structure of border and trail lichens also suggested that the southern part of the calving ground was still heavily used in the early 1990s. Length and growth rate of C. stellaris thallus were closely associated with severity of caribou disturbance, as inferred from the residual ground cover of terrestrial lichens. Growth performance of C. stellaris during the initial stage of lichen recovery varied according to the spatial use of the summer habitat by caribou, with better performance at the edge of the summer and winter habitats and reduced performance in the extensively used calving ground. The analysis of growth performance of C. stellaris provides new insights on lichen-spruce stand recovery associated with caribou disturbance.

Characteristics of Early-Winter Caribou, <em>Rangifer tarandus caribou</em>, Feeding Sites in the Southern Purcell Mountains, British Columbia

Mountain Caribou are a rare ecotype of Woodland Caribou (Rangifer tarandus caribou) inhabiting the high-snowfall region of southeastern British Columbia, and are defined by their late-winter reliance on arboreal hair lichen of the genus Bryoria. During early winter, there is considerable variation in habitat use among populations. We snow-trailed Caribou in the southern Purcell Mountains during early winter to determine foraging patterns for the Purcell population. When snow was ≤51 cm deep, Caribou fed on Grouseberry (Vaccinium scoparium), the terrestrial lichen Cladonia, and arboreal lichens of the genus Bryoria. When snow was ≥62 cm deep, they ate exclusively arboreal lichens. In both periods, Caribou ate arboreal lichen from essentially every downed tree or branch encountered and fed with a higher intensity at downed trees than standing trees. During the low-snow period, Caribou fed at fewer trees but used those with greater lichen abundance, and fed more intensively at each, compared to the deep-snow period. In comparison to trees occurring on the foraging path but at which Caribou did not feed, those from which arboreal lichen was foraged intensively were of larger diameter, had greater lichen abundance, and were more likely to be Subalpine Fir (Abies lasiocarpa) or Engelmann Spruce (Picea engelmannii) and less likely to be Whitebark Pine (Pinus albicaulis), Lodgepole Pine (P. contorta) or Alpine Larch (Larix lyalli). The shift in diet between the low-snow and deep-snow periods reflected two modes of foraging within the early winter period, distinct from one another and apparently also distinct from the late-winter season. Management for early-winter habitat will require retention of some commercially significant forest across extensive areas, both near the subalpine forest – subalpine parkland ecotone and lower in the subalpine forest.

Preliminary assessment of habitat characteristics of woodland caribou calving areas in the Claybelt region of Québec and Ontario, Canada

Woodland caribou (Rangifer tarandus caribou) require a diversity of forested habitats over large areas and may thus be particularly affected by the large-scale changes in the composition and age-class distribution of forest landscapes induced by the northern expansion of forest management. In this study we examine habitat characteristics associated to the use of calving areas by woodland caribou females and calves at different spatial scales. Thirty females were captured and collared with Argos satellite transmitters that allowed to locate 14 calving areas. Field surveys were conducted at each of these areas to measure the landscape composition of forest cover types and local vegetation characteristics that are used for both forage conditions and protection cover. At the scale of the calving area, univariate comparisons of the amount of forest cover types between sites with and without calves showed that the presence of calves was associated to mature black spruce forest with a high percent cover of terrestrial lichens. Within calving grounds, univariate comparisons showed that vegetation features like ericaceans and terrestrial lichens, that are important food resources for lactating females, were more abundant in calving areas where females were seen with a calf in mid-July than in areas where females were seen alone. The protection of the vegetation cover against predators was however similar between calving areas with or with¬out a calf. Logistic regression results also indicated that vegetation characteristics associated to forage conditions were positively associated to calf presence on calving grounds. Our results suggest that foraging conditions should be given more attention in analyses on habitat requirements of woodland caribou.

Lichen guilds share related cyanobacterial symbionts.

Lichen guilds share related cyanobacterial symbionts.