Kalmia Angustifolia Research Articles

Mechanical scarification can reduce competitive traits of boreal ericaceous shrubs and improve nutritional site quality

Abstract Ericaceous shrubs often interfere with the growth of black spruce seedlings on regenerating forest sites in Eastern Canada. Mechanical site preparation such as scarification may improve this situation, but it is uncertain whether this is solely due to a reduction in direct competition from the shrubs, or also from a sustained improvement in nutritional site quality. We sampled experimental plots in two boreal climate regions (i.e. warmer-drier Abitibi vs. cooler-wetter Côte-Nord) where scarification, performed 18 years earlier, had increased the growth of black spruce relative to non-scarified plots. Trees of scarified plots had closed the canopy more than trees of non-scarified plots in Côte-Nord, but not in Abitibi. Total ground cover of ericaceous shrubs was lower in scarified plots at both sites, the main species being Kalmia angustifolia (i.e. Kalmia) in Abitibi and Rhododendron groenlandicum (i.e. Labrador tea) in Côte-Nord. Scarified plots at both sites had significantly shorter current-year ericaceous rhizomes than non-scarified plots, but the difference between treatments was significantly greater in Côte-Nord than in Abitibi. In Côte-Nord, ericaceous shrubs on scarified plots had a lower specific rhizome mass, higher specific leaf area, lower tannin and higher N concentrations in leaves and litter, and lower N use efficiency than on non-scarified plots. By comparison, scarification in Abitibi affected only one foliar property, namely a reduction in the C:N ratio of Kalmia leaf litter. Forest floor N mineralization rates and black spruce needle N concentrations were higher in scarified than non-scarified plots across both sites. Taken collectively, results suggest that mechanical scarification on ericaceous shrub-dominated cutovers can reduce competitive traits of boreal ericaceous shrubs and improve nutritional site quality, especially in cooler-wetter climates.Highlights

Post-Fire Habitat Heterogeneity Leads to Black Spruce–Kalmia L. Shrub Savannah Alternate State

Many nutrient-poor coarse-textured Kalmia L.–black spruce forest sites in eastern Canada turn to ericaceous heath dominated by Kalmia angustifolia L. after clearcutting and fire. While the mechanisms of post-fire forest and heath formation have been well documented, the origin of shrub savanna vegetation has received limited attention. This study demonstrates the significance of post-fire island regeneration of black spruce in Kalmia heath to the origin of shrub savannah alternate state. The study was conducted in Three Brooks, 10 km west of Grand Falls-Windsor, Newfoundland (48°51′ N; 55°37′ E). Black spruce forest in the site was clearcut, then a wildfire burned the area, and the site was subsequently planted with black spruce. Plant species cover, black spruce growth (stem density, stem height, basal diameter, and yearly volume increment), and foliar nutrients of planted spruce and soil properties (pH, humus and Ae horizon depth, and nutrients) in tree islands were compared with adjacent Kalmia heath. Black spruce islands had significantly lower cover of Kalmia and higher stem density of black spruce compared to Kalmia heath (7100 stems/ha in islands vs. 1920 stems/ha in heath). Height, basal diameter, and yearly volume increment of black spruce were more than three times higher in spruce islands than in Kalmia heath. Foliar nutrients of black spruce growing in Kalmia heath had significantly lower N and Mg (33 and 38%, respectively) but had significantly higher Mn and Zn (46 and 33%, respectively) than in black spruce islands. Black spruce growth inhibition in Kalmia heath is attributed to soil nutrient imbalance due to Kalmia evidenced by reduced concentrations of N and Mg and increased concentrations of Al, Fe, and other inorganic ions in the foliage. These results suggest that post-fire black spruce islands in severely burned patches provide “safe sites” for spruce regeneration, whereas Kalmia heath developing in non-severe burn area inhibits spruce regeneration and creates shrub savannah community as an alternate vegetation state.

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.

Antioxidant, Anti-Inflammatory, and Anti-Aging Potential of a Kalmia angustifolia Extract and Identification of Some Major Compounds.

Skin aging is the most visible element of the aging process, giving rise to a major concern for many people. Plants from the Ericaceae family generally have antioxidant and anti-inflammatory properties, making them potential anti-aging active ingredients. This study aimed to evaluate the safety and anti-aging efficacy of a Kalmia angustifolia extract using reconstructed skin substitutes. The safety evaluation was performed using a 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, while the efficacy was determined by assessing antioxidant and anti-inflammatory activity and analyzing skin substitutes reconstructed according to the self-assembly method by histology and immunofluorescence staining (elastin, collagen-1, collagen-3, aquaporin-3). The cell viability assay established the safety of the extract at a concentration up to 200 μg/mL. The Oxygen Radical Absorbance Capacity (ORAC) assay and a cell-based assay using 2’,7’-dichlorofluorescein-diacetate (DCFH-DA) revealed a strong antioxidant activity with an ORAC value of 16 µmol Trolox Equivalent/mg and a half-maximal inhibitory concentration (IC50) of 0.37 ± 0.02 μg/mL, while an interesting anti-inflammatory activity was found in the inhibition of NO production, with an inhibition percentage of NO production of 49 ± 2% at 80 µg/mL. The isolation and characterization of the extract allowed the identification of compounds that could be responsible for these biological activities, with two of them being identified for the first time in K. angustifolia: avicularin and epicatechin-(2β-O-7, 4β-6)-ent-epicatechin. Histological analyses of skin substitutes treated with the extract showed an increase in dermal thickness compared with the controls. K. angustifolia extract enhanced the expression of elastin and collagen-1, which are usually decreased with skin aging. These results suggest that K. angustifolia has promising antioxidant efficacy and anti-aging potential.

Foliar Spectra and Traits of Bog Plants across Nitrogen Deposition Gradients

Bogs, as nutrient-poor ecosystems, are particularly sensitive to atmospheric nitrogen (N) deposition. Nitrogen deposition alters bog plant community composition and can limit their ability to sequester carbon (C). Spectroscopy is a promising approach for studying how N deposition affects bogs because of its ability to remotely determine changes in plant species composition in the long term as well as shorter-term changes in foliar chemistry. However, there is limited knowledge on the extent to which bog plants differ in their foliar spectral properties, how N deposition might affect those properties, and whether subtle inter- or intraspecific changes in foliar traits can be spectrally detected. The objective of the study was to assess the effect of N deposition on foliar traits and spectra. Using an integrating sphere fitted to a field spectrometer, we measured spectral properties of leaves from the four most common vascular plant species (Chamaedaphne calyculata, Kalmia angustifolia, Rhododendron groenlandicum and Eriophorum vaginatum) in three bogs in southern Québec and Ontario, Canada, exposed to different atmospheric N deposition levels, including one subjected to a 18-year N fertilization experiment. We also measured chemical and morphological properties of those leaves. We found detectable intraspecific changes in leaf structural traits and chemistry (namely chlorophyll b and N concentrations) with increasing N deposition and identified spectral regions that helped distinguish the site-specific populations within each species. Most of the variation in leaf spectral, chemical, and morphological properties was among species. As such, species had distinct spectral foliar signatures, allowing us to identify them with high accuracy with partial least squares discriminant analyses (PLSDA). Predictions of foliar traits from spectra using partial least squares regression (PLSR) were generally accurate, particularly for the concentrations of N and C, soluble C, leaf water, and dry matter content (<10% RMSEP). However, these multi-species PLSR models were not accurate within species, where the range of values was narrow. To improve the detection of short-term intraspecific changes in functional traits, models should be trained with more species-specific data. Our field study showing clear differences in foliar spectra and traits among species, and some within-species differences due to N deposition, suggest that spectroscopy is a promising approach for assessing long-term vegetation changes in bogs subject to atmospheric pollution.

Fire Behaviour Observation in Shrublands in Nova Scotia, Canada and Assessment of Aids to Operational Fire Behaviour Prediction

Parks Canada, in collaboration with Nova Scotia Lands and Forests and Natural Resources Canada, documented shrub fire behaviour in multiple plots burned over two periods: a spring period in June 2014 and a summer period in July 2017. The study area, located within Cape Breton Highlands National Park, comprised fifteen burn units (20 m by 20 m in size). Each unit was ignited by line ignition and burned under a wide range of conditions. Pre-burn fuel characteristics were measured across the site and used to estimate pre-fire fuel load and post-fire fuel consumption. This fuel complex was similar to many flammable shrub types around the world, results show that this shrub fuel type had high elevated fuel loads (3.17 ± 0.84 kg/m2) composed of exposed live and dead stunted black spruce as well as ericaceous shrubs, mainly Kalmia angustifolia (evergreen) and Rhodora canadensis (deciduous). Data show that the dead moisture content in this fuel complex is systematically lower than expected from the traditional relationship between FFMC and moisture content in the Canadian Fire Weather Index System but was statistically correlated with Equilibrium Moisture Content. A significant inverse relationship between bulk density and fire rate of spread was observed as well as a clear seasonal effect between the spring burns and the summer burns, which is likely attributable to the increase in bulk density in the summer. Unlike most shrub research, wind and dead moisture content did not have a statistically significant association with fire spread rates. However, we believe this to be due to noise in wind data and small dataset. Rate of spread as high as 14 m/min and flame lengths over 4 m were recorded under Initial Spread Index values of 6.4 and relative humidity of 54%. A comparison with a number of well-known shrubland spread rate prediction models was made. An aid to operational fire prediction behaviour is proposed, using a fuel type from the Canadian Fire Prediction System (O-1b) and a modified estimate of fuel moisture of the elevated fuel in the fuel complex.

Pre-commercial thinning enhances competitive traits of boreal ericaceous shrubs and reduces soil fertility

Boreal ericaceous shrubs, such as Kalmia angustifolia, have evolved various traits allowing them to interfere with the growth of conifer trees. These include the ability to spread through rhizomatous growth and to produce high amounts of tannins that interfere with soil N cycling. We examined how pre-commercial thinning (PCT) of young black spruce (Picea mariana) stands, a common silvicultural practice, increases the aboveground and belowground spread of various ericaceous shrubs, the chemical quality of leaves and litter, as well as soil nitrogen cycling. We compared these effects in relatively cool-moist and relatively warm-dry climates. Within the warm-dry climate, we also compared the effects of PCT on fertile clay and on nutrient-poor till deposits. The total cover of ericaceous shrubs was higher in PCT than in control plots in all three site types. On nutrient poor till deposits (in both climates), the current-year rhizome length and specific rhizome mass of K. angustifolia were higher in PCT than in control plots. Soil mineralizable NH4+-N was lower under patches of K. angustifolia than under patches of feather moss (Pleurozium schreberi). Across all 24 plots, canopy openness had a positive relationship with ericaceous shrub cover, current-year rhizome length, foliar tannins and phenolic concentrations. Although PCT might increase tree growth in the short-term, its positive effects on ericaceous shrubs increases the risk of conifer seedling growth check when the next clearcut harvest occurs, especially in cool moist climates and on nutrient poor soil deposits.

Alternate successional pathway yields alternate pattern of functional diversity

AbstractQuestionIn Eastern Canada, wildfires turn Picea mariana forests into Kalmia angustifolia dominated heath or P. mariana forest depending on burn severity. These alternate end‐points of succession provide an opportunity to test assumptions concerning alternate successional trajectories dominated by distinct plant functional groups. Disturbance effects on functional diversity (FD) have been studied largely in single post‐disturbance communities, but rarely applied to alternate successional pathways. Do post‐fire Kalmia heaths have lower FD than forest communities, and does heath formation select for a narrow range of traits leading to biotic homogenization?LocationTerra Nova National Park, Newfoundland, Canada.MethodsBased on five functional traits (specific leaf area, leaf dry matter content, seed mass, height, specific root length), we measured functional trait dispersion within (alpha FD) and between sites (beta FD). We calculated overall FD metrics in nine heath and four forest sites as well as metrics for three functional groups (trees, shrubs, and herbs) in each site. We also performed a complementary taxonomic diversity (TD) analysis to establish links between FD and TD.ResultsWe could not detect a difference in overall alpha TD between the two successional communities but found significant loss of alpha and beta FD in heaths and within tree and herb groups. Overall beta FD was lower in heaths than forests. It was also lower for trees and herbs, indicating an increase in functional similarity (functional homogenization) of the majority of life forms.ConclusionsBetween the two successional pathways, trait space occupancy was lower in heaths than forests. Heath formation in post‐fire communities consistently restricts functional dispersion (low alpha FD) of tree and herb traits leading to functional homogenization (low beta FD). When a successional trajectory leads to heath formation, it is accompanied by a loss of functional diversity.

The spread of Kalmia angustifolia on black spruce forest cutovers contributes to the spatial heterogeneity of soil resources.

Kalmia angustifolia is a boreal ericaceous shrub that can rapidly spread on black spruce forest cutovers in eastern Canada, where CPRS (i.e. Cutting with Protection of Regeneration and Soils”) is practiced. The proliferation of Kalmia often coincides with a reduction in the growth rate of regenerating black spruce seedlings. We report on a study where we compared the local effects of Kalmia and black spruce seedling patches (i.e. two types of “Vegetation”) on chemical and biochemical soil properties in CPRS cutovers within mesic spruce-moss and xeric spruce-lichen ecosystems, as well as in four mature spruce-moss forests (i.e. three “Site Types”). Results from 13C-CPMAS-NMR revealed lower O-alkyl C (i.e. carbohydrates), higher aromatic C (i.e. lignin and other phenolics) and higher carbonyl-C (i.e. amide-C and carboxyl groups) in spruce-moss than in spruce-lichen forest floors (F-horizon). In spite of these distinctions, we observed only a small number of Site Type x Vegetation interactions controlling soil properties. Vegetation had a significant effect on ten forest floor properties. Most notably, Kalmia patches had higher concentrations of condensed tannins and lower mineral N cycling. On the other hand, Site Type had a relatively greater effect on the deeper podzolic-B horizons, where mineral N and microbial activity were higher in mature spruce-moss forests than in the cutovers. Green and senescent Kalmia leaves collected at these sites had higher N, tannin and phenolic concentrations than green and senescent spruce needles. A 25 month litter bag study found lower decomposition of Kalmia leaf litter in spruce patches on spruce-lichen cutovers compared to spruce patches on spruce-moss cutovers, or to Kalmia patches on spruce-lichen cutovers. Given that black spruce seedlings obtain most of their nutrients from the forest floor, our results suggest that CPRS may have long-term negative effects on black spruce forest productivity if the spread of Kalmia is left unchecked.

Local environment, not local adaptation, drives leaf-out phenology in common gardens along an elevational gradient in Acadia National Park, Maine.

Climate-driven changes in phenology are substantially affecting ecological relationships and ecosystem processes. The role of variation among species has received particular attention; for example, variation among species' phenological responses to climate can disrupt trophic interactions and can influence plant performance. Variation within species in phenological responses to climate, however, has received much less attention, despite its potential role in ecological interactions and local adaptation to climate change. We constructed three common gardens across an elevation gradient on Cadillac Mountain in Acadia National Park, Maine, to test population-level responses in leaf-out phenology in a reciprocal transplant experiment. The experiment included three native species: low bush blueberry (Vaccinium angustifolium), sheep's laurel (Kalmia angustifolia), and three-toothed cinquefoil (Sibbaldiopsis tridentata). Evidence for local adaptation of phenological response to temperature varied among the species, but was weak for all three. Rather, variation in phenological response to temperature appeared to be driven by local microclimate at each garden site and year-to-year variation in temperature. Population-level adaptations in leaf-out phenology appear to be relatively unimportant for these species in Acadia National Park, perhaps a reflection of strong genetic mixing across elevations, or weak differences in selection on phenological response to spring temperatures at different elevations. These results concur with other observational data in Acadia and highlight the utility of experimental approaches to understand the importance of annual and local site variation in affecting phenology both among and within plant species.

Growth release of stunted black spruce (Picea mariana) in Kalmia heath: the role of ectomycorrhizal fungi and near-ground microclimate

Naturally regenerating and planted black spruce (Picea mariana (Mill.) B.S.P.) in post-fire landscapes in eastern Canada often exhibit stunted growth in the presence of ericaceous shrubs such as Kalmia angustifolia L. After a period of stunted growth, some seedlings experience a growth release, exhibiting growth rates closer to normally growing seedlings. We hypothesized that an increase in colonization of root tips by ectomycorrhizal (ECM) fungi is responsible for this release and that the percentage of root tips colonized by ECM fungi would be higher on seedlings that had a released or normally growing neighbour within close proximity. We quantified ECM fungi diversity and abundance from 255 soil cores from stunted, released, and normally growing black spruce seedlings sampled in two Kalmia-dominated sites in Newfoundland. Growth and microsite characteristics around each seedling were also measured. We found that normal and released seedlings had significantly higher proportions of ECM fungi root tips than stunted seedlings, supporting our final hypothesis; however, there was no significant difference in distance between neighbours. Soil chemical properties are thought to inhibit the vegetative spread of ECM fungi species in this particular system and are identified as an important topic for further research.

Belowground interactions between Kalmia angustifolia and Picea mariana: roles of competition, root exudates and ectomycorrhizal association

Belowground competition and allelopathic interference of neighbouring plants play important roles in shaping plant performance. We assessed the effect of belowground interactions involving root competition, root exudates and ectomycorrhizal (ECM) association between Kalmia and black spruce on above- and belowground biomass increment and foliar nutrient content of black spruce seedlings. We predicted that root competition and root exudates of Kalmia would exert a negative impact on black spruce performance, while ECM in black spruce would exert positive impacts on its performance. In a greenhouse experiment, using the neutral growth medium of peat-vermiculite, we planted Kalmia and black spruce seedling in pairs. We controlled root competition by placing fine wire mesh between the seedlings and applied benomyl fungicide to control ectomycorrhizae. We used activated charcoal to neutralize the potential allelopathic effects associated with root exudates. After 8 months, we evaluated the performance of black spruce seedlings in terms of biomass, abundance of ectomycorrhizal short roots and foliar nutrient concentrations. To determine treatment effects on soil processes, we also analysed soil pH, total phenols, C:N ratio and bioavailable nitrogen (NO3− and NH4+) at the end of the experiment. We found a significant effect of root competition on root-shoot ratio and biomass increment in black spruce seedlings, which achieved the highest root-shoot ratio and biomass increment when major root competition was controlled. Kalmia produced twice the root biomass than black spruce. Surprisingly, charcoal and benomyl treatments—which remove the effects of Kalmia allelopathy on black spruce and suppress ECM growth, respectively—had little or no significant effect on overall biomass of black spruce. In contrast, Kalmia biomass increment and root-shoot ratio were maximized in benomyl treatment. Soil pH and C:N ratio were significantly higher in free competition than root exclusion and benomyl treatments and with activated charcoal. Kalmia root competition mediated by high root biomass is the predominant driver shaping neighbourhood interactions between Kalmia and black spruce, which in turn shape the performance of black spruce seedlings. Root exudates of Kalmia have a very weak effect on black spruce seedling growth.

Bluejoint Is an Effective Bio-Barrier Species on Mine Covers.

Covers with capillary barrier effects (CCBE) are used to prevent acid mine drainage from mine wastes in the short term. However, the long-term efficiency of CCBE can be affected by trees because their roots may reduce the ability of covers to limit oxygen migration and also physically damage the CCBE. Two plant species that are native to boreal Canada, bluejoint () and sheep laurel (, were selected as bio-barrier species (BBS) to test if they reduce the growth and root system architecture of trees established on mine covers (balsam poplar [], willow [ spp], and black spruce []). The experiment was established in 2008 on a mine tailings impoundment located in northwestern Quebec, Canada. Trees were measured for height, diameter, and biomass. Coarse roots were excavated from the plots and digitized in three dimensions. Compared with the control (no BBS), bluejoint strongly decreased tree height and diameter increment, biomass, maximum root depth and radial extension, total root length and volume, and number of second- and third-order tree roots. Height and diameter increment, biomass, maximum root depth and volume, and number of second-order roots of balsam poplar increased with sheep laurel compared with control conditions, whereas willow showed no response to this treatment. Most characteristics of black spruce (except root-to-shoot ratio and number of second-order roots) improved in the presence of sheep laurel compared with the control. Thus, bluejoint was a more efficient BBS than sheep laurel. Bio-barriers comprised of bluejoint can be used as a countermeasure for controlling tree invasion of CCBE.

Genome Sizes and Ploidy Levels in the Genus Kalmia

Kalmia is a highly ornamental genus of shrubs native to North America and Cuba and grown as a valuable nursery crop throughout much of the temperate world. Although most species of Kalmia have previously been found to be diploid with 2n = 2x = 24, one species, Kalmia polifolia, has been found to be tetraploid. However, sampling within the genus has been limited, and information on the ploidy levels of specific cultivars is lacking. The objective of this study was to determine the relative genome sizes and ploidy levels of species, hybrids, and cultivars of Kalmia. Flow cytometry was used to determine the relative genome sizes of 67 accessions representing species, interspecific hybrids, cultivars, and chemically induced polyploids. Traditional cytology was used to calibrate genome sizes with ploidy levels. Results showed that relative genome sizes were conserved with 1Cx values ranging from 0.57 pg for Kalmia carolina to 0.70 pg for Kalmia latifolia. Most species of Kalmia were diploid including K. buxifolia (Leiophyllum buxifolium), K. carolina, K. cuneata, K. hirsuta, K. latifolia, and K. microphylla. Although plants of K. carolina (Kalmia angustifolia var. carolina) were uniformly diploid, the closely related, but more northerly distributed, K. angustifolia was primarily tetraploid, providing additional justification for treating these as separate species. An unusual triploid of K. angustifolia f. candida was also documented. Kalmia polifolia included both tetraploid and potentially pentaploid individuals, indicating a ploidy series within this species. Kalmia latifolia cultivars also included one triploid, two cytochimeras, and two chemically induced tetraploids. Overall, polyploidy was more prevalent in Kalmia than previously reported and varied both within and among species. This broader survey of relative genome sizes and ploidy levels in Kalmia provides valuable information for plant breeders and new insights into the systematics and cytogenetics of the genus.

Abundance and Diversity of Wild Bees (Hymenoptera: Apoidea) Found in Lowbush Blueberry Growing Regions of Downeast Maine.

Insect-mediated pollination is critical for lowbush blueberry (Ericaceae: Vaccinium angustifolium Aiton) fruit development. Past research shows a persistent presence of wild bees (Hymenoptera: Apoidea) providing pollination services even when commercial pollinators are present. We undertook the study to 1) provide a description of bee communities found in lowbush blueberry-growing regions, 2) identify field characteristics or farm management practices that influence those communities, 3) identify key wild bee pollinators that provide pollination services for the blueberry crop, and 4) identify non-crop plants found within the cropping system that provide forage for wild bees. During a 4-year period, we collected solitary and eusocial bees in over 40 fields during and after blueberry bloom, determining a management description for each field. We collected 4,474 solitary bees representing 124 species and 1,315 summer bumble bees representing nine species. No bumble bee species were previously unknown in Maine, yet we document seven solitary bee species new for the state. These include species of the genera Nomada, Lasioglossum, Calliopsis, and Augochloropsis. No field characteristic or farm management practice related to bee community structure, except bumble bee species richness was higher in certified organic fields. Pollen analysis determined scopal loads of 67-99% ericaceous pollen carried by five species of Andrena. Our data suggest two native ericaceous plants, Kalmia angustifolia L. and Gaylussacia baccata (Wangenheim), provide important alternative floral resources. We conclude that Maine blueberry croplands are populated with a species-rich bee community that fluctuates in time and space. We suggest growers develop and maintain wild bee forage and nest sites.

Ecological gradients driving the distribution of four Ericaceae in boreal Quebec, Canada.

Understory species play a significant role in forest ecosystem dynamics. As such, species of the Ericaceae family have a major effect on the regeneration of tree species in boreal ecosystems. It is thus imperative to understand the ecological gradients controlling their distribution and abundance, so that their impacts can be taken into account in sustainable forest management. Using innovative analytical techniques from landscape ecology, we aimed to position, along ecological gradients, four Ericaceae found in the boreal forest of Quebec (Canada) (Rhododendron groenlandicum, Kalmia angustifolia, Chamaedaphne calyculata, and Vaccinium spp), to regionalize these species into landscape units relevant to forest management, and to estimate the relative importance of several ecological drivers (climate, disturbances, stand attributes, and physical environment) that control the species distribution and abundance. We conducted our study in boreal Quebec, over a study area covering 535,355 km2. We used data from 15,339 ecological survey plots and forest maps to characterize 1422 ecological districts covering the study region. We evaluated the relative proportion of each ericaceous species and explanatory variables at the district level. Vegetation and explanatory variables matrices were used to conduct redundancy, cluster, and variation partitioning analyses. We observed that ericaceous species are mainly distributed in the western part of the study area and each species has a distinct latitudinal and longitudinal gradient distribution. On the basis of these gradients, we delimited 10 homogeneous landscape units distinct in terms of ericaceous species abundance and environmental drivers. The distribution of the ericaceous species along ecological gradients is closely related to the overlaps between the four sets of explanatory variables considered. We conclude that the studied Ericaceae occupy specific positions along ecological gradients and possess a specific abundance and distribution controlled by the integration of multiple explanatory variables.

Above-Ground Net Primary Production from Vascular Plants Shifts the Balance Towards Organic Matter Accumulation in Restored Sphagnum Bogs

The organic matter accumulation potential of a restored bog was estimated over 2 years as a balance be- tween losses to decomposition and inputs through above- ground net primary productivity (AGNPP) in five micro- habitats of increasing complexity (relating to the moss car- pet thickness and the number of vegetation functional groups). Decomposition and accumulation rates variations were hypothesized to lead to higher organic matter accumu- lation potential in the more complex micro-habitats. In general, for a given litter type, the mass losses and decom- position rates were rather homogeneous between micro- habitats, but, they were correlated to the cover of particular species: Eriophorum vaginatum with slower decomposition rates, and Ledum groendlandicum or Kalmia angustifolia with higher rates. Therefore, the abundance of some peatland species, rather than the habitat complexity itself, was a driver of decomposition rates. While the Sphagnum AGNPP did not compensate for decomposition losses, the organic matter accumulation potential was tipped towards a sink (positive) by the contribution of vascular species to the AGNPP. The organic matter accumulation potentials are much improved by the presence of Sphagnum, but from a restoration perspective, promoting the growth of vascular peatland species might also be a key to achieving a positive balance of organic matter accumulation.

History of the series on the Biology of Canadian Weeds

In the mid-1960s the founding of the Canadian Botanical Association provided a forum for the discussion of new botanical initiatives in Canada. At that time there was, coincidentally, a much increased interest in several areas of botany that had previously been little studied or ignored (e.g., plant autecology, plant population biology). As a result, many research projects became focused on individual species or small groups of closely related species. Botanists studying the native flora as well as those working with weed species became aware of the need for the compilation of all available information on important species, essentially in the format pioneered in Great Britain in the ‘‘Biological Flora of the British Isles’’. Botanists from the Central Experimental Farm in Ottawa (the Plant Research Institute) and the Botany Department at the University of Western Ontario in London decided to prepare a manuscript format for a Canadian version of the Biological Flora. Gerald Mulligan and Paul Cavers agreed to undertake this work. The initial plan was to ask the Editorial Board of the Canadian Journal of Botany to initiate a series with a tentative title ‘‘The Biological Flora of Canada’’. However, the Editor of the Canadian Journal of Botany did not accept this proposal. When we re-examined all the letters and other material received while the original proposal was being prepared, it was evident that by far the greatest support had come from scientists studying weeds and invasive plant species. In particular, many members of the Canada Weed Committee (later known as the Expert Committee on Weeds and currently as the Canadian Weed Science Society) enthusiastically recommended that this series be established. The Agricultural Institute of Canada, publishers of the Canadian Journal of Plant Science, agreed to publish the series under the title ‘‘The Biology of Canadian Weeds’’. We quickly revised the manuscript format to include aspects of weed biology not featured in the original proposal and published it in July 1972 (Cavers, P. B. and Mulligan, G. A. 1972. A new series The Biology of Canadian Weeds. Canadian Journal of Plant Science 52: 651 654). Gerry Mulligan was the first Editor of the series and Paul Cavers took the lead in finding authors and maintaining a list of Accounts in Preparation. The first account, published in October 1973, dealt with sheep-laurel (Kalmia angustifolia L.), a native species that is a weed of lowbush blueberry fields and pastures in eastern Canada. Since then, more than 150 accounts have been published, many on two or more species. In recent years, updates of several of the early accounts have been published. These updated accounts incorporate information on well-studied species published after the original account appeared. The series was popular from the outset, in fact there was such a great demand for many articles that the authors’ stocks of reprints soon were exhausted. In 1979, a book containing the first 32 accounts in the series was published by Agriculture Canada. Gerald Mulligan was the Editor and Compiler. In 1984, a second volume containing the next 29 accounts, with the same Editor/ Compiler and publisher, was printed. Volumes 3, 4 and 5 were published with Paul Cavers as the Editor/ Compiler by the Agricultural Institute of Canada in 1995, 2000 and 2005. In total, 129 original accounts plus three updated accounts were published in these five volumes (Table 1). In 2003, a new complimentary series was started, ‘‘The Biology of Invasive Alien Plants in Canada’’, in response to an expanding need for information on plants newly established or showing increased expansion in Canada, but for which there may be relatively little information available in a Canadian context. This series was intended to be similar in style and scope, but to concentrate on non-native plant species that have been more recently introduced into Canada than many of our common agricultural weeds, and for which there is substantial evidence that they may generate adverse economic impacts and management difficulties in agricultural systems or a broader landscape. The format for the Biology of Canadian Weeds has changed little over the years. Each contribution consists of 13 sections. The first section lists the currently accepted scientific name and the English and French vernacular names plus any synonyms that appear in the weed literature. The second section begins with a brief

Lichen-Spruce Woodland Early Indicators of Ecological Resilience Following Silvicultural Disturbances in Québec’s Closed-Crown Forest Zone

Lichen woodlands (LW) located in the closed-crown boreal forest are not a successional stage moving towards a closed black spruce feathermoss stand (FM), but an alternative stable state, due to their previous forest history, and the occurrence of LWs located nearby closed-crown FM stands. Therefore, afforestation in those LWs through site preparation and plantation could shift back LW into FM stands. We implemented an experimental design with different combinations of silvicultural treatments in both site types (LW, FM). We monitored the evolution of plant diversity and the physiology of three bio-indicators (Picea mariana, Kalmia angustifolia, Rhododendron groenlandicum) in different microsites created by the silvicultural treatments. The return to the initial composition was noticed only two years after treatments, especially in the LW stands, thus indicating a higher level of early ecosystem resilience in LWs compared to FM stands. Mean species cover, especially in the FM stands, decreased the most in the skid trails created by logging, probably due to a lack of acclimation of bryophytes to open stand conditions. Conversely, ericaceous shrubs and lichens found in the LWs were already acclimated to open stand conditions, which give to LWs a restructuring advantage compared to FM plant communities after silvicultural treatments. Overall, FM and LW short-term resilience was similar, indicating equally efficient ecosystem reorganization in both stands. The comparable early resilience in managed LW and FM stands, in terms of plant biodiversity, contradicts the presumed fragility of LW stands, especially in this case where LWs are assumed to be an alternative stable state created by compound disturbances. Silvicultural treatments maintained the functional group diversity in LWs, a key element for ecosystem resilience. Therefore, this study support the idea that plantation following site preparation in LWs could be a valuable management strategy to reach several objectives, such as increasing forest carbon sinks.

The Relative Importance of Nitrogen vs. Moisture Stress May Drive Intraspecific Variations in the SLA-RGR Relationship: The Case of <i>Picea mariana</i> Seedlings

Plants acclimate to nitrogen (N) or moisture stress by respectively increasing photosynthetic N use efficiency (PNUE) or water use efficiency (WUE), in order to maximize their relative growth rate (RGR). These two phenotypic adaptations have opposite effects on specific leaf area (SLA). Thus, intraspecific variations in the SLA-RGR relationship should reflect the relative importance of N vs. moisture stress in plants. In this study, we measured needle gas exchanges and N concentrations in order to derive PNUE and WUE, as well as SLA and RGR of black spruce (Picea mariana) seedlings growing on a rapidly drained site in the presence or absence of Kalmia angustifolia. The eradication of Kalmia had resulted in a ~140% increase in seedling growth over a 6 year period. We found a negative SLA-RGR relationship where Kalmia had been eradicated, and a positive one where Kalmia had been maintained. Kalmia eradication resulted in higher WUE when measurements were made directly on the seedlings, and in lower PNUE when twigs were rehydrated prior to gas exchange measurements. Our data suggest that the bigger seedlings on Kalmia-eradicated plots increase RGR by decreasing SLA, as a means of coping with moisture stress. By contrast, increasing SLA on noneradicated plots may be a means of coping with nutrient stress exerted by Kalmia. The SLA-RGR relationship could potentially be used to identify the limiting resource for black spruce seedlings in different environments.