Ericaceous Species Research Articles

From death comes life: Large vertebrate carrion enhances seedling establishment in clonal ericaceous shrubs

Abstract Carrion can have disproportionally large effects on ecological processes and community dynamics. During decomposition, the influx of growth‐limiting nutrients can create small‐scale disturbances with high soil cover known as ‘cadaver decomposition islands’ (CDIs). Such disturbances can allow for altered plant species composition, increased biomass production or provide microsites for regeneration. Carcasses also provide a resource for omnivorous scavengers, which have the potential to direct endozoochorous seed dispersal towards developing CDIs. In this study, we investigated functional links between the scavenger community, carcass‐induced disturbances in vegetation and the seedling establishment of berry‐producing ericaceous species. We experimentally placed out 30 vertebrate carcasses of various species in a boreal forest ecosystem, each paired with a control and a mechanically disturbed plot to track vertebrate animal activity (i.e. dispersal vectors), vegetation changes (i.e. recruitment windows) and seedling establishment. We hypothesized that carcass size and season of experimental deposition would affect (H1) scavenger community composition and (H2) formation of CDIs, and that (H3) seedling establishment of ericaceous species is more abundant at CDIs compared with control or disturbed plots without carcass deposition. We found that carcass presence effectively created a spatiotemporal hotspot of animal activity and that 94% of observations of vertebrates at carcasses were of species with the potential for ericaceous seed dispersal. Larger carcasses (e.g. moose, reindeer) attracted similar and abundant vertebrate communities, whereas observations at small carcasses (e.g. red fox) resembled those at control plots (H1). Only larger carcasses led to CDI formation (i.e. potential recruitment microsites), while plots with small carcasses resembled control plots (H2). Surprisingly, the season of carcass deposition did not influence vertebrate composition at carcass plots or CDI formation (H1–2). Seedlings were significantly more abundant in CDIs compared with mechanical disturbance and control plots (H3). Overall, CDIs contained about 4 and 19 times more seedlings compared with disturbed and controls, respectively. Our study demonstrates how individual carcasses in a boreal forest landscape can facilitate sexual reproduction in ericaceous keystone species. We suggest that this pathway also occurs in other ecosystems and that it may contribute to the genetic diversity of plant populations. Read the free Plain Language Summary for this article on the Journal blog.

From simple metrics to cervid forage: Improving predictions of ericaceous shrub biomass

Common understory vegetation species such as the ericaceous shrubs bilberry (Vaccinium myrtillus), cowberry (V. vitis-idaea) and heather (Calluna vulgaris), are key forage plant species for moose and other large herbivores, as well as fulfilling many additional ecosystem functions and services. Here we developed models to predict above-ground biomass of these ericaceous species in coniferous forests, using data on their percentage cover, height, and different stand characteristics. We also built models to understand how the aforementioned variables affect the proportion of the shrubs commonly utilized as forage by large herbivores. We found that the percentage cover of shrubs was the most important explanatory variable when predicting above-ground biomass, explaining 51%, 47% and 71% of the variation (marginal R2) in bilberry, cowberry and heather biomass, respectively. By adding ramet height to the model with percentage cover, the variation explained increased to 77% for bilberry, 75% for cowberry and 87% for heather. The best outcome for candidate models was obtained by adding stand site index and spruce basal area to the model, improving the variation explained in bilberry to 83%, to 81% for cowberry, and 91% for heather. When modelling the proportion of the shrubs commonly utilized as forage by large herbivores, stand site index and spruce basal area often played important roles. Some of the best fitting models for forage biomass explained 51% of the variation in bilberry, 59% in cowberry and 30% in heather. Site location did not have a major role in improving the variability explained in either type of model, which indicated the applicability of the models regardless of study location. Our models therefore have a high potential to be implemented in forestry decision support systems. Their inclusion should provide better large-scale estimations of forage resources, aiding forest management, and thereby taking an important step forward to determine the ecosystem carrying capacity of large herbivores.

Habitat Protection Approaches Facilitate Conservation of Overlooked Fungal Diversity - A Case Study From the Norwegian Coastal Heathland System.

European coastal heathlands are distinct ecosystems shaped by land use tradition and they have experienced an 80% area reduction from their historical maximum. These mosaics of mires and wind exposed patches have ericaceous shrub dominated vegetation, and soils within coastal heathlands are characterized by low pH and high levels of recalcitrant debris. Using a culture-based approach with molecular identification of isolates, we characterized root-associated fungal communities of six ericaceous species in eight heathland localities along Norway's western coast. Site-level alpha diversity ranged from 21-38 OTUs, while the total estimated gamma diversity for culturable heathland root fungi was 190-231 OTUs. Most species recovered are previously reported at low abundance in Norway, suggesting the biodiversity in this community is underreported, rather than novel for science. The fungi recovered were primarily Ascomycota, specifically endophytic Phialocephala, and Pezicula, and no host specificity was observed in the communities. The fungal communities exhibited high turnover and low nestedness, both between ericaceous hosts and across heathland sites. We observed no spatial patterns in fungal betadiversity, and this heterogeneity may be a product of the unique historic land use practices at each locality creating a distinct mycofloral "fingerprint". Robust diversity estimates will be key for managing fungal biodiversity in coastal heathlands. Our results indicate that sampling schemes that maximize the number of host plants sampled per site, rather than the number of cultures per plant yield improved alpha diversity estimates. Similarly, gamma diversity estimates are improved by maximizing the total number of localities sampled, rather than increasing the number of plants sampled per locality. We argue that while the current protected status of coastal heathland habitats and restoration efforts have knock-on effects for the conservation of fungal biodiversity, fungi have a vital functional role in the ecosystem and holistic conservation plans that consider fungal biodiversity would be beneficial.

Directed endozoochorous dispersal by scavengers facilitate sexual reproduction in otherwise clonal plants at cadaver sites.

The regeneration niche of many plant species involves spatially and temporally unpredictable disturbances, called recruitment windows of opportunity. However, even species with clear dispersal adaptations such as fleshy berries may not successfully reach such elusive regeneration microsites. Ericaceous, berry‐producing species in the northern hemisphere demonstrate this dispersal limitation. They are said to display a reproductive paradox owing to their lack of regeneration in apparently suitable microsites despite considerable investment in producing large quantities of berries.Cadavers generate vegetation‐denuded and nutrient‐rich disturbances termed cadaver decomposition islands (CDIs). Cadavers attract facultative scavengers with considerable capacity for endozoochorous seed dispersal. We hypothesize that CDIs facilitate recruitment in berry‐producing ericaceous species due to endozoochorous dispersal directed toward favorable microsites with low competition.We examined seedling establishment within a permanent, semi‐regular 10 × 10 m grid across an ungulate mass die‐off on the Hardangervidda plateau in southeastern Norway. Competing models regarding the relative importance of factors governing recruitment were evaluated, specifically cadaver location (elevated seed rain) and microsite conditions (competition).We found that CDIs did facilitate seedling establishment, as cadaver density was the best predictor of seedling distribution. Other important factors governing seedling establishment such as percentage cover of soil and vascular plants alone were inadequate to explain seedling establishment. Synthesis: This study provides a novel understanding of sexual reproduction in species with cryptic generative reproduction. The directed nature of endozoochorous dispersal combined with long‐distance dispersal abilities of medium to large vertebrate scavengers toward cadavers allows plants to exploit the advantageous but ephemeral resource provided by CDIs.

Legacies of historic charcoal production affect the forest flora in a Swedish mining district

Iron production was historically associated with major impacts on forests worldwide, as vast amounts of wood were harvested to produce the charcoal needed for heating the furnaces and reducing iron oxides in the ore to iron. This impact has left abundant legacies which potentially may remain in the present‐day vegetation. We investigated how remains of historic charcoal production, mainly from the 18th to the early 20th century, at still remaining charcoal kiln platforms (CKPs), affect the current species richness, species occurrences and cover of vascular plants in the ground vegetation in a Swedish mining district located in the boreo‐nemoral forest zone. CKPs have a significantly higher species richness than the surrounding forest, and they also affect cover (negatively) for ericaceous species typically dominating the forest ground vegetation. Several forest species are more frequent at CKPs, and these also harbor significantly more uncommon species, of which many are typical for traditionally managed grasslands. These latter species are likely to represent remnants in present‐day forests reflecting former land‐use such as livestock grazing. The soil chemistry at CKPs is strongly deviating from the surrounding forest, and this, together with a lower cover of ericaceous shrubs, are the most likely mechanisms behind the higher species richness. CKPs represent conspicuous and abundant historic anthropogenic habitats in the forest vegetation. As far as we are aware, the flora at CKPs in boreal and boreo‐nemoral forests has not previously been investigated in detail, and they deserve more attention, both from a biological and a cultural–historical perspective.

The seed germination of berry-producing ericaceous shrubs in relation to dispersal by hare

ABSTRACT Hare pellets contribute greatly to the seed dispersal of a berry-producing shrub, Gaultheria miqueliana Takeda (Ericaceae), on Mount Koma, northern Japan. Numerous seeds of G. miqueliana germinated from the hare pellets (122.2 ± 7.3/pellet, mean ± SE), confirming that the pellets potentially had a role in the seed dispersal. Lab-experiments confirmed that the seeds of G. miqueliana needed light for full germination without cold stratification. Besides, hare pellets were collected from a post-mined peatland in Sarobetsu Mire, northern Japan, where G. miqueliana was not distributed but two berry-producing ericaceous species were distributed. No seeds germinated on the pellets collected from the Mire. These results suggested that the tight relationships between hare and berry-producing shrubs were species-specific.

Ericaceous species reduce methane emissions in sheep and red deer: Respiration chamber measurements and predictions at the scale of European heathlands

Despite the importance of atmospheric methane as a potent greenhouse gas and the significant contribution from ruminant enteric fermentation on methane emissions at a global scale, little effort has been made to consider the influence that different plant-based natural diets have on methane emissions in grazing systems. Heathland is an ericaceous dwarf-shrub-dominated habitat widespread across the northern hemisphere, in Europe, provides valuable ecosystem services in areas with poor soils, such as water flow regulation, land-based carbon skin, energy reservoir and habitat of key game species. We (i) measured methane emissions from red deer (Cervus elaphus) and sheep (Ovis aries) fed mixed diets of natural grass plus ericaceous species (either Calluna vulgaris or Vaccinium myrtillus) using open-circuit respiration chambers; and (ii) modelled the results to estimate methane emissions from red deer and sheep populations inhabiting heathland habitats across Europe under different scenarios of grass-based mixed diets with varying proportions of ericaceous species. Our results indicated that methane emissions per unit of digestible organic matter intake decreased as the proportion of ericaceous species in diet increased, but this relationship was complex because of the significant interaction between the proportion of ericaceous species in the diet and digestible organic matter intake. According to our estimates red deer and sheep populations across European heathlands produce 129.7 kt·y−1 methane (se = 1.79) based on a hypothetical grass-ericaceous species mixed diet containing 30% of ericaceous species; this is 0.5% of total methane emissions from human activity across Europe (24,755 kt·y−1), and a reduction in methane emissions of 63.8 kt·y−1 against the same deer and sheep populations, if assumed to consume a grass-only diet. We suggest the implementation of carbon credits as a measure to value the relevance of heathland systems to promote biodiversity and its potential contribution to reduce methane emissions in ruminant grazing systems.

Impacts of Vaccinium arboreum Rootstocks on Vegetative Growth and Yield in Two Southern Highbush Blueberry Cultivars

Vaccinium arboreum Marsh is a small tree adapted to low-organic matter soils and is one of the few ericaceous species that tolerates soil pH greater than 6.0. It has a deep root system and is more drought tolerant than cultivated blueberry. The use of V. arboreum as a rootstock for commercial blueberry production has been studied previously in young blueberry plantings. The objective of the current study was to expand on earlier work and evaluate growth, productivity, and tolerance to bacterial leaf scorch (Xylella fastidiosa) in established plantings of own-rooted vs. grafted southern highbush blueberry (SHB). Two field plantings of grafted and own-rooted ‘Meadowlark’ and ‘Farthing’ SHB were established in May 2011: one at the University of Florida–Institute of Food and Agricultural Sciences (UF-IFAS) Plant Science Research and Education Unit in Citra, FL, and the other at a commercial blueberry farm in Archer, FL. At both sites, four rootstock–scion combinations were grown in either pine bark-amended or nonamended soil. Canopy volume was greater in grafted compared with own-rooted ‘Meadowlark’ at both locations throughout the 4 years of the study (2015–18), whereas canopy volume in ‘Farthing’ was not consistently different. For both cultivars and both locations, canopy volume was greater on amended compared with nonamended soil. Although canopy growth was not consistently increased in the grafted compared with own-rooted plants, yield was greater in grafted plants of both cultivars at both locations. Cumulative yield over the 4 years was similar between grafted plants grown on both amended and nonamended soil, and was significantly greater than yield of own-rooted plants on nonamended soil, suggesting the use of this rootstock may decrease the requirement for pine bark amendment. In general, grafted plants produced larger berries, with no negative impacts on fruit soluble solids, titratable acidity, or firmness. ‘Meadowlark’—an SHB cultivar that exhibits high sensitivity to bacterial leaf scorch—displayed decreased development of bacterial leaf scorch symptoms when grafted onto V. arboreum compared with own-rooted plants. These results indicate the potential benefits of grafting SHB onto V. arboreum rootstock, particularly under marginal soil conditions. However, a complete economic analysis that also takes into account any differences in longevity between the two systems must be done to determine whether the benefits of using grafting are feasible financially for the grower.

Endozoochory by brown bears stimulates germination in bilberry

The understory vegetation of the Eurasian boreal forest is dominated by several ericaceous species (e.g. bilberry Vaccinium myrtillus). These species invest large amounts of energy in their sexual reproduction by producing seed-containing berries, which are apparent adaptations for endozoochory. Their seedlings are, however, almost never found in the wild, and they reproduce virtually exclusively through clones. Brown bears Ursus arctos consume enormous amounts of ericaceous berries (predominantly bilberry in central Scandinavia) during hyperphagia, and may facilitate sexual reproduction in such species. If ericaceous species would benefit from endozoochory by brown bears, one would predict that endozoochory would have no negative impacts on germination. We experimentally evaluated this prediction using germination trials under controlled conditions of bilberry seeds that were 1) extracted from brown bear feces, 2) extracted from ripe berries and 3) contained in berries. Using time-to-event analyses, we showed that passing the gut by itself did not stimulate or limit germination. However, seeds that were released from the berries germinated about one month earlier compared to seeds contained in berries. This implies that being released from a fruit, for example through endozoochory, can have a large temporal germination and growth advantage, especially in northern ecosystems a with short growing season.

Altitudinal Shift of Tetrao urogallus in an Alpine Natura 2000 Site: Implications for Habitat Restoration

Capercaillie (Tetrao urogallus L.), a territorial galliform species, is known to prefer mature conifer stands with canopy gaps and a vigorous understory of ericaceous species. Capercaillie is a useful umbrella species that has recently shown declining population trends and distribution changes in its southern geographic range. We aim to identify and assess the possible changes in summer capercaillie habitat selection between 2001 and 2011 in the Scanuppia Natura 2000 site (south-eastern Alps). The area is dominated by spruce (Picea abies (L.) Karsten) forests, followed by mixed forests, scrub, and open habitats. In both years, summer presence–absence of capercaillie was verified through the detection of droppings over 10 m radius circular plots located along contour lines (1500–1800 m). A set of environmental and habitat features was also surveyed. While overall population numbers remain unchanged over the surveyed period, results have shown an altitudinal shift in capercaillie distribution. Habitat variables had a stronger effect on the presence of capercaillie in 2001 than in 2011. Land cover and climate change are likely among the drivers of the shift in altitudinal distribution. This confirms the relevance of habitat restoration actions and to monitor changes in factors explaining capercaillie habitat selection.

Autogenic ecological succession of a pristine peat bog: focus on factors affecting beetle diversity

ABSTRACTElements of the ancient periglacial flora such as peat bog shrubs provide a paleorefugium in Central Europe for survival of glacial biota and other cold-adapted species during recent climate change. This study provides evidence that diversity of one of the most numerous consumers in peat bogs, beetles, was higher in mid-successional stages characterized by the highest degree of shrub encroachment, compared with early and old stages. The main autogenic factor driving successional changes of herb-shrub layer coleopteran assemblages were shrub cover and bog water level. Younger successional stages contained the highest abundance of herb dwellers (chortobionts) and polyphagous species, whereas middle and old stages contained shrub inhabitants (chamebionts), which are oligophagous species specializing on ericaceous dwarf shrubs. Species richness and abundance of cold-adapted inhabitants of peat bogs (tyrphobiontic and tyrphophilous) increased from young to old successional stages along with increased shrub cover. Herb dwellers and polyphagous species are among the first primary consumers to colonize peat bogs. With changes in late-successional habitats, in particular the invasion of ericaceous dwarf shrubs, chamebiontic and oligophagous species start colonizing.

Root system origin and structure influence planting shock of black spruce seedlings in boreal microsites

Planting shock can last for several years during which seedling growth may significantly slow down. This duration depends upon the time that is required for the root system to acclimatize to its new environment. We hypothesized that characteristics of the root system are important factors for black spruce (Picea mariana [Mill.] BSP) seedling establishment. To test this hypothesis, we compared growth and physiology of three stock types: containerized seedlings, with a dense initial root system restricted to the volume of a root plug; deeply planted containerized seedlings, with the stem buried during production to develop dense adventitious and initial root systems; and bareroot seedlings, with a less developed but unrestricted initial root system. The three stock types were planted on three microsites that are typical of reforestation sites found in eastern Canadian boreal forest: (1) bare mineral soil; (2) in presence of ericaceous shrubs; or (3) in presence of Sphagnum spp. and ericaceous species. Labelled nitrogen fertilizer was added to half of the seedlings to compare nitrogen uptake. We measured seedling growth (height, diameter, above- and belowground biomass), nutrition (including 15N uptake) and 13C discrimination (as an indicator of water stress) at the end of the second growing season. Except at the root level, there were few interactions between stock types and microsites. For fertilized microsites, we speculate that ericaceous species captured most added nutrients since seedlings that were planted directly on mineral soil had greater height and diameter increments than seedlings with competing vegetation. In unfertilized microsites, Sphagnum spp. and ericaceous species had significant negative effects on seedling growth. For stock type, the presence of a root plug allowed containerized and deeply planted seedlings to have a lower δ13C, suggesting less water stress compared to bareroot seedlings. Strong initial root system development of containerized seedlings resulted in greater total biomass. We hypothesized that the presence of adventitious roots in deeply planted seedlings positively influenced nutrient uptake, particularly N. As nutrient availability is one of the most limiting factors in the boreal forest, we suggest using deeply planted containerized seedlings to reduce planting stress.

Comparison of Root Surface Enzyme Activity of Ericaceous Plants and Picea abies Growing at the Tree Line in the Austrian Alps

Plants with ericoid mycorrhizal and ectomycorrhizal associations coexist at the tree line and in many boreal forests. Both ericoid mycorrhizal and ectomycorrhizal roots are known to produce extracellular enzymes, but ericoid mycorrhizal fungi have been demonstrated in vitro to have higher enzyme activities. On hair roots of four ericoid mycorrhizal species (Rhododendron ferrugineum, Vaccinium vitis-idaea, Vaccinium myrtillus, Calluna vulgaris) and on ectomycorrhizal and non-mycorrhizal root tips of Picea abies growing at the tree line (1700 m) in the Austrian Alps, potential activities of eight extracellular root enzymes were estimated. Our results show that the activities of all the different extracellular root enzymes were generally similar among the ericaceous plant species. The mean laccase enzyme activity of ectomycorrhizal root tips of Picea abies was significantly higher than that of both the hair roots and fine roots of the ericaceous species. Leucine-amino-peptidase activity on hair roots was significantly higher than on non-mycorrhizal fine roots for the ericaceous vegetation. However, the mean activity of β-glucuronidase of the ericaceous species was significantly higher in fine roots compared to the hair roots. Generally extracellular root enzyme activity is not higher on ericaceous roots compared to ectomycorrhizas of Picea abies.

Is Mechanized Harvesting of Shrubs Grown for Energy Purposes Environmentally Sustainable?

Mechanized harvesting of shrub formations as part of sustainable forest management not only helps reduce the risk of forest fires in Mediterranean environments but also provides economic benefit from the extracted biomass, contributing to the development of the bioeconomy. However, these mechanized operations require an environmental impact assessment to identify the short-term impacts, both positive and negative. This is especially important in the Mediterranean basin given the specific climatic conditions which exist. In this study, the environmental impact of mechanized shrub harvesting is analyzed in relation to (i) changes in biodiversity and in the presence and growth of species; (ii) physical and chemical properties of the soil; and (iii) changes in forest fire risk. For this purpose, a pre-harvest inventory was conducted and post-harvest monitoring schedules of 1- and 2-year durations were established in three characteristic Mediterranean shrubland formations located in the northern–central area of the Iberian Peninsula. Our results reveal that the recovery rates in biodiversity indices after harvesting were very high, with values ranging from 30 to 70% depending on the site. Two years after harvesting, the species coverage was similar to the pre-harvest scenario in some locations, although not with regards to height, the ericaceous species being those with the greatest sprouting capacity. Significant changes in the physical and chemical properties of soils were also observed. In this regard, negative impacts such as soil compaction or slight acidification were identified at some sites. However, positive effects were also found such as an increment in carbon and nitrogen content after harvesting, along with increased litter quantity a year from the clearing operation due to biomass residue left on the ground after harvesting. Furthermore, mechanical harvesting effectively modified fire behavior in all the shrub formations 2 years after clearing, with a notable reduction in fire risk at all the studied sites.

Plant\u2013plant interactions could limit recruitment and range expansion of tall shrubs into alpine and Arctic tundra

Species in cold-limited biomes are expected to expand their distribution ranges in response to climate warming. For plants, range shifts can only occur via successful recruitment beyond their current distribution limit. However, many environmental and ecological filters can act upon recruitment and establishment, thereby potentially limiting the expected climate-driven shifts. In this study, we investigate potential mechanical and chemical constraints that vegetation above the tall shrubline in alpine and Arctic tundra could impose upon the successful establishment of willow species in the Canadian Western Arctic. We collected willow seeds from an alpine and an Arctic shrubline and conducted germination trials to test (1) for seedbed preferences among three natural and one experimentally scarified seedbeds, and (2) for vulnerability to allelopathic chemicals produced by ericaceous dwarf shrub species. We found that germination was almost four times higher on manually exposed bare ground than on intact, herbaceous vegetation. Seeds of two willow species, Salix arctica and Salix pulchra, were not affected by leaf extracts from dwarf shrubs, Cassiope tetragona and Vaccinum uliginosum, but the germination of Salix richardsonii was reduced by as much as 24% in the presence of chemicals from C. tetragona. Our results suggest that biotic interactions could limit the predicted expansion of tall shrubs in the tundra by interfering with germination. Seemingly species-specific responses highlight the need for replicated studies across a wider range of species combinations. Potential range shifts may not occur as a uniform translocation of the shrubline, but could change the composition of the plant community by filtering out certain species.

Evidence that Blueberry Floral Extracts Influence Secondary Conidiation and Appressorial Formation of Colletotrichum fioriniae.

Blueberry anthracnose, caused by Colletotrichum fioriniae, is a pre- and postharvest disease of cultivated highbush blueberry (Vaccinium corymbosum). During disease development, the pathogen undergoes several lifestyle changes during host colonization, including epiphytic, quiescent, and necrotrophic phases. It is not clear, however, what if any host signals alter the pattern of colonization during the initial epiphytic phase and infection. This research investigated the role of blueberry floral extracts (FE) on fungal development. Results show that FE significantly increased both the quantity and rate of secondary conidiation and appressorial formation in vitro, suggesting that floral components could decrease the minimum time required for infection. Activity of FE was readily detected in water collected from field samples, where secondary conidiation and appressorial formation decreased as rainwater collections were further removed from flowers. A comparison of FE from four blueberry cultivars with different levels of field susceptibility revealed that appressorial formation but not secondary conidiation significantly increased with the FE from susceptible cultivars versus resistant cultivars. Inoculum supplemented with FE produced higher levels of disease on ripe blueberry fruit as compared with inoculum with water only. Flowers from other ericaceous species were found to also induce secondary conidiation and appressorial formation of C. fioriniae. This research provides strong evidence that flowers can contribute substantially to the infection process of C. fioriniae, signifying the importance of the bloom period for developing effective disease management strategies.

Mechanical site preparation and nurse plant facilitation for the restoration of subarctic forest ecosystems

Sustainable forest management implies successful regeneration following disturbances. Tree regeneration in subarctic ecosystems can, however, be constrained by limitations to seedling establishment related to cold soils, slow decomposition rates, and competition by ericaceous species. We established a field trial at the northern limit of commercial forests in Québec, Canada, to evaluate to what extent mechanical site preparation (MSP) and planting of a nurse N2-fixing species could promote conifer establishment on a site burned in 2007. The experiment comprised four treatments applied in 2010: standard MSP (disc trenching), standard MSP plus planting of Alnus crispa, intensive MSP, with larger furrows than standard MSP, and a control. Main plots were divided and planted in 2011 with Picea mariana (Mill.) Britton, Stearns & Poggenb. or Pinus banksiana Lamb. We monitored seedling survival, growth, nutrition, and microsite over a 3-year period. Results revealed interactions between treatments and planted species. Mechanical site preparation resulted in higher conifer growth relative to the control conditions, and planting Alnus resulted in growth gains similar to those obtained from intensive MSP. We measured competitive interactions between Alnus and the conifers that might eventually cancel out the initial benefits derived from facilitation by planting the nurse species. Longer term monitoring of interspecific interactions is needed to unravel the mechanisms responsible for the facilitative effect and identify the best management practices.

Effect of forest clear cuts on plant–pollinator interactions: the case of three ericaceous subshrubs in Lithuanian pine forests

Managed boreal pine forests are subject to regular clear cuts causing significant disturbances to these ecosystems. It is believed that, to some extent, they resemble natural cycles of forest growth, decline, and regeneration and can benefit, e.g., mutualistic relations among plants and pollinators. To study the impact of forest management (clear cuts) on pollinator visitation, we focused on three ericaceous plant species, <em>Vaccinium myrtillus</em>, <em>V. vitis-idaea</em>, and <em>Calluna vulgaris</em>, common elements of pine forest understory. Our observations, conducted in Lithuania, showed that there are no differences among control mature stands and clear cut areas in terms of visitation frequency for all three studied species. However, at least for <em>C. vulgaris</em>, a shift toward fly visits was observed in the clear cut site, showing that open areas are preferred habitats for these insects. Ants constituted an important share of visitors to flowers of <em>V. myrtillus</em> and <em>C. vulgaris</em>, suggesting their important role in reproduction of these plant species.

Diversity of fungal assemblages in roots of Ericaceae in two Mediterranean contrasting ecosystems

The plants belonging to the Ericaceae family are morphologically diverse and widely distributed groups of plants. They are typically found in soil with naturally poor nutrient status. The objective of the current study was to identify cultivable mycobionts from roots of nine species of Ericaceae (Calluna vulgaris, Erica arborea, Erica australis, Erica umbellate, Erica scoparia, Erica multiflora, Arbutus unedo, Vaccinium myrtillus, and Vaccinium corymbosum). The sequencing approach was used to amplify the Internal Transcribed Spacer (ITS) region. Results from the phylogenetic analysis of ITS sequences stored in the Genbank confirmed that most of strains (78) were ascomycetes, 16 of these were closely related to Phialocephala spp, 12 were closely related to Helotiales spp and 6 belonged to various unidentified ericoid mycorrhizal fungal endophytes. Although the isolation frequencies differ sharply according to regions and ericaceous species, Helotiales was the most frequently encountered order from the diverse assemblage of associated fungi (46.15%), especially associated with C. vulgaris (19.23%) and V. myrtillus (6.41%), mostly present in the Loge (L) and Mellousa region (M). Moreover, multiple correspondence analysis (MCA) showed three distinct groups connecting fungal order to ericaceous species in different regions.

Comparison of fine-scale spatial genetic structure of two sympatricRhododendronshrub species in forest habitat having different seed weights: A case study

AbstractRestricted seed dispersal is one of the most prevalent determinants of spatial genetic structure (SGS) at a fine spatial scale within a plant population.Rhododendron kaempferiandR. semibarbatumare common and coexistent Ericaceous species in the shrub layer of secondary deciduous broad-leaved forests in the northern Kanto District, central Japan. The two species have entomophilous flowers and are thought to have similar pollination styles. However,R. kaempferiproduces threefold heavier seeds thanR. semibarbatum. Therefore, we tested the hypothesis that the intensity of SGS was stronger inR. kaempferithan inR. semibarbatumin a forest stand. We comparatively examined the SGS for 73 individuals ofR. kaempferiand 36 individuals ofR. semibarbatumby using highly variable nuclear microsatellite loci. The analysis revealed significant SGS in both species at the shortest distance (<3 m); a measure to quantify SGS showed a counterintuitive result:R. semibarbatumexhibited stronger SGS thanR. kaempferi. This result might be explained by the ecological consequences ofR. semibarbatumproducing lighter seeds, which might have greater dispersal efficacy, but its safe sites could be more restricted than those ofR. kaempferi; in contrast,R. kaempferiproducing heavier seeds might have more limited seed dispersal, but its safe sites for seedling establishment could be more prevalent than those forR. semibarbatum. The different strategies for the trade-off between seed weight and site selection of the twoRhododendronspecies might be reflected in the difference in the intensity of SGS in this study plot.