Kalmia Latifolia Research Articles

Dispensing Pollen via Catapult: Explosive Pollen Release in Mountain Laurel (Kalmia latifolia).

The astonishing amount of floral diversity has inspired countless assumptions about the function of diverse forms and their adaptive significance, yet many of these hypothesized functions are untested. We investigated an often-repeated adaptive hypothesis about how an extreme floral form functions. In this study, we conducted four investigations to understand the adaptive function of explosive pollination in Kalmia latifolia, the mountain laurel. We first performed a kinematic analysis of anther movement. Second, we constructed a heat map of pollen trajectories in three-dimensional space. Third, we conducted field observations of pollinators and their behaviors while visiting K. latifolia. Finally, we conducted a pollination experiment to investigate the importance of pollinators for fertilization success. Our results suggest that insect visitation dramatically improves fertilization success and that bees are the primary pollinators that trigger explosive pollen release.

An evaluation of seven methods for controlling mountain laurel thickets in the mixed-oak forests of the central Appalachian Mountains, USA

In the Appalachian Mountains of eastern North America, mountain laurel (Kalmia latifolia) thickets in mixed-oak (Quercus spp.) stands can lead to hazardous fuel situations, forest regeneration problems, and possible forest health concerns. Therefore, land managers need techniques to control mountain laurel thickets and limit their deleterious effects. From 2001 to 2009, I compared the effectiveness of seven understory management techniques (two chemical, two fire, two mechanical, and an untreated control) for reducing mountain laurel thickets. All of the methods except the control decreased mountain laurel coverage for at least 2years and facilitated establishment of oak seedlings and other hardwood reproduction. However by the fifth year, the mountain laurel thickets had nearly redeveloped and the reproduction of several other hardwood species were outgrowing the oak seedlings. Additionally, all of the methods had operational issues that limited their effectiveness. Research into broadcast herbicides that kill the mountain laurel long-term and prevent redevelopment is needed as none of the techniques tested in this study provided effective control beyond a few years.

Characteristics, Histories, and Future Succession of Northern Pinus pungens Stands

Pinus pungens (Table Mountain pine) stands are rare conifer-dominated communities that occur on xeric ridges and upper slopes throughout the central and southern Appalachian Mountains. At the northern end of this range, this uncommon forest community is essentially unstudied. Therefore, in 2006 I initiated a dendroecology study of three Pinus pungens stands growing in Pennsylvania to better understand their current conditions, histories, and likely future succession. These stands contained from four to 14 tree species with Pinus pungens or Quercus montana (chestnut oak) dominating the main canopy. Quercus coccinea (scarlet oak), Acer rubrum (red maple), or Nyssa sylvatica (black gum) were the primary species of the midstory. Kalmia latifolia (mountain laurel) was the principal understory shrub. Two of the communities had Pinus pungens and Quercus montana trees dating back into the mid-1800s and were likely heavily influenced by the charcoal iron industry of that century. Periodic fire was also part of their history. The other Pinus pungens community arose following abandonment of an agricultural field in the 1910s and fire does not seem to have been a factor in its ecological history. Two of the communities appear to be losing their Pinus pungens component as their understories are dominated by hardwood saplings or shrubs and there are no pine seedlings present. Perpetuating these and other Pinus pungens communities in Pennsylvania will require reducing the understory vegetation and creating suitable seed beds for Pinus pungens seedling establishment.

Origin, development, and impact of mountain laurel thickets on the mixed-oak forests of the central Appalachian Mountains, USA

Throughout forests of the northern hemisphere, some species of ericaceous shrubs can form persistent understories that interfere with forest regeneration processes. In the Appalachian Mountains of eastern North America, mountain laurel (Kalmia latifolia) may interfere in the regeneration of mixed-oak (Quercus spp.) forests. To verify this possibility, I conducted a dendroecology study from 2001 to 2005 in three mixed-oak stands with mountain laurel thickets to elucidate how and when the thickets originated, developed, and were impacting hardwood seedlings. At all three sites, the oldest mountain laurel dated to the 1930s when the stands emerged from a period of recurring disturbance. However, most of the mountain laurel has originated since the 1950s when the stands were generally undisturbed. More recently, insect defoliations have accelerated the development of the thickets by increasing available sunlight. A strong negative relationship exists between the percent cover of mountain laurel and the density of hardwood seedlings with 20–30% cover being sufficient to inhibit seedling establishment and survival. Perpetuating mixed-oak forests that contain mountain laurel thickets will require reducing shrub cover to less than 20–30% at the beginning of the regeneration process to help ensure adequate densities of hardwood seedlings.

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.

Impacts of repeated wildfire on long-unburned plant communities of the southern Appalachian Mountains

The infrequent occurrence of large wildfires in the southern Appalachian Mountains over the last several decades has offered few opportunities to study their impacts. From 2000 to 2008, five wildfires burned a large portion of the area in and surrounding the Linville Gorge Wilderness in North Carolina. Areas were burned either once or twice. The response of acid cove and thermic oak plant communities (structure, cover, richness, diversity) was measured in 78 vegetation monitoring plots, established in 1992 and remeasured in 2010–11. Fire altered forest structure in both communities, resulting in the mortality of larger trees and increases in the abundance of smaller (<5 cm diameter at breast height (DBH)) stems. Burning twice decreased stem counts for mountain laurel (Kalmia latifolia) in both communities, whereas oaks (Quercus spp.) responded positively to burning twice in the thermic oak community. Table Mountain pine stem counts increased in acid cove and thermic oak communities burned once. Fire appears to promote princesstree (Paulownia tomentosa) invasion. Herbaceous species cover responded positively to fire (once or twice; both communities), with concurrent increases in woody species richness and diversity. Tree species composition in acid cove plots was not affected by burning, although some slight changes occurred in thermic oak plots burned twice.

First Report of Phytophthora hydropathica Causing Wilting and Shoot Dieback on Viburnum in Italy

The genus Viburnum comprises over 150 species of shrubs and small trees such as Laurustinus (Viburnum tinus L.), which is one of the most widely used ornamental plants in private and public gardens. Furthermore, it commonly forms stands of natural woodland in the Mediterranean area. In autumn 2012, a survey was conducted to determine the presence of Phytophthora ramorum on Viburnum in commercial nurseries in the Latium region where wilting, dieback, and death of twigs were observed on 30% of the Laurustinus plants. A Phytophthora species was consistently recovered from soil rich in feeder roots from potted Laurustinus plants showing symptoms. Soil samples were baited with rhododendron leaves. Small pieces of leaf tissue cut from the margin of lesions were plated on P5ARPH selective medium (4). Pure cultures, obtained by single-hypha transfers on potato dextrose agar (PDA), were petaloid. Sporangia formation was induced on pepper seeds (3). Sporangia were almost spherical, ovoid or obpyriform, non-papillate and non-caducous, measuring 36.6 to 71.4 × 33.4 to 48.3 μm (average 53.3 × 37.4 μm) with a length/width ratio of 1.4. Chlamydospores were terminal and 25.2 to 37.9 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in culture or on the host. All isolates examined had 30 to 35°C as optimum temperatures. Based on these morphological characteristics, the isolates were identified as Phytophthora hydropathica (2). Morphological identification was confirmed by internal transcribed spacer (ITS), and mitochondrial partial cytochrome oxidase subunit 2 (CoxII) with BLAST analysis in the NCBI database revealing 99% identity with ITS and 100% identity with CoxII. The sequences of the three isolates AB234, AB235, and AB236 were deposited in European Nucleotide Archive (ENA) with the accession nos. HG934148, HG934149, and HG934150 for ITS and HG934151, HG934152, and HG934153 for CoxII, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from V. tinus plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis into the phloem. Controls were treated as described above except that sterile PDA plugs replaced the inoculum. Shoots were incubated in test tubes with sterile water in the dark at 24 ± 2°C. After 2 weeks, lesions were evident at the inoculation points and symptoms were similar to those caused by natural infection. P. hydropathica was consistently re-isolated from the margin of lesions, while controls remained symptomless. In the United States in 2008, P. hydropathica was described as spreading from irrigation water to Rhododendron catawbiense and Kalmia latifolia (2). This pathogen can also attack several other horticultural crops (1), but to our knowledge, this is the first report of P. hydropathica causing wilting and shoot dieback on V. tinus.

Pollen Dispersal by Catapult: Experiments of Lyman J. Briggs on the Flower of Mountain Laurel

The flower of Kalmia latifolia L. employs a catapult mechanism that flings its pollen to considerable distances. Physicist Lyman J. Briggs investigated this phenomenon in the 1950s after retiring as longtime director of the National Bureau of Standards, attempting to explain how hydromechanical effects inside the flower’s stamen could make it possible. Briggs’s unfinished manuscript implies that liquid under negative pressure generates stress, which, superimposed on the stress generated from the flower’s growth habit, results in force adequate to propel the pollen as observed. With new data and biophysical understanding to supplement Briggs’s experimental results and research notes, we show that his postulated negative-pressure mechanism did not play the exclusive and crucial role that he credited to it, though his revisited investigation sheds light on various related processes. Important issues concerning the development and reproductive function of Kalmia flowers remain unresolved, highlighting the need for further biophysical advances.

To sprout or not to sprout: Multiple factors determine the vigor ofKalmia latifolia(Ericaceae) in southwestern Connecticut

Kalmia latifolia has declined in southern New England and other parts of its range in recent decades. This long-term decline is generally attributed to abiotic forces (i.e., low light levels in maturing forests) with little attention to the possible role that top-down effects from ungulate herbivory may be playing. We examined the extent to which mature K. latifolia is capable of sprouting under a relatively undisturbed forest canopy—both after severe stem injury and when uninjured—and tested the hypothesis that, in areas with high deer densities, herbivory may exceed abiotic forces in controlling the dynamics of K. latifolia. A block design experiment with white-tailed deer (Odocoileus virginianus) exclusion and control as treatments and landscape position (hilltop and low slope) as block was established in 2008. Canopy openness was measured in the two treatments within each block using hemispherical canopy photos. Survival and sprouting vigor of cut and uncut K. latifolia stems were monitored over 4 years and analyzed using Bayesian Information Criteria model selection with deer herbivory, percent canopy openness, and slope position as predictor variables. Canopy openness and slope position were important drivers of adult K. latifolia survival and sprouting capacity, whereas deer herbivory and slope position were the most important drivers of sprouting vigor on cut stems. Our results suggest that in a relatively undisturbed forest with high deer densities, herbivory does not exceed abiotic factors in determining adult K. latifolia vigor over the short term, but herbivory and slope position are more important than light in determining sprouting vigor after stem cutting.

The distribution of a non-native (Rosa multiflora) and native (Kalmia latifolia) shrub in mature closed-canopy forests across soil fertility gradients

Background and aims A soil fertility gradient, ranging from infertile to highly fertile soils, may define whether or not a plant will establish and spread at a site. We evaluated whether or not such a fertility gradient exists for Rosa multiflora Thunb., a nonnative invasive shrub, and Kalmia latifolia L., a native problem shrub, in closed-canopy forests of the eastern U.S.

Landscape Scale Ecosystems of the Pine Mountain Range, Georgia

ABSTRACT Landscape scale analysis of the vegetation of the Pine Mountain Range of west-central Georgia revealed fourteen plant communities. This unique mountain chain at the southern border of the Piedmont has a plant composition with a mixture of Appalachian, Piedmont, and Coastal Plain species. Dry ridgetops supported Pinus palustris and Quercus laevis, while steep moist slopes have Kalmia latifolia and Rhododendron minus as a component. Communities on calcareous soils include ridgetops with an Aesculus pavia midstory and savannah-like areas with an overstory of P. palustris and understory of Gymnopogon brevifolius and Rhus aromatica. Quercus georgiana was common and widespread in the southern portions of the range, especially in FDR State Park. The moist valleys have provided a refuge for Appalachian and Coastal Plain species, while the uplands harbor P. palustris ecosystems and a Castanea dentata stand. Due to the unique species composition, conservation efforts should focus on returning fire as an ec...

Toxic compounds in honey

There is a wealth of information about the nutritional and medicinal properties of honey. However, honey may contain compounds that may lead to toxicity. A compound not naturally present in honey, named 5-hydroxymethylfurfural (HMF), may be formed during the heating or preservation processes of honey. HMF has gained much interest, as it is commonly detected in honey samples, especially samples that have been stored for a long time. HMF is a compound that may be mutagenic, carcinogenic and cytotoxic. It has also been reported that honey can be contaminated with heavy metals such as lead, arsenic, mercury and cadmium. Honey produced from the nectar of Rhododendron ponticum contains alkaloids that can be poisonous to humans, while honey collected from Andromeda flowers contains grayanotoxins, which can cause paralysis of limbs in humans and eventually leads to death. In addition, Melicope ternata and Coriaria arborea from New Zealand produce toxic honey that can be fatal. There are reports that honey is not safe to be consumed when it is collected from Datura plants (from Mexico and Hungary), belladonna flowers and Hyoscamus niger plants (from Hungary), Serjania lethalis (from Brazil), Gelsemium sempervirens (from the American Southwest), Kalmia latifolia, Tripetalia paniculata and Ledum palustre. Although the symptoms of poisoning due to honey consumption may differ depending on the source of toxins, most common symptoms generally include dizziness, nausea, vomiting, convulsions, headache, palpitations or even death. It has been suggested that honey should not be considered a completely safe food.

Inoculum Density Relationships for Infection of Some Eastern US Forest Species by Phytophthora ramorum

AbstractOur objectives were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole‐plant inoculations. Young plants and detached leaves of Quercus prinus (Chestnut oak), Q. rubra (Northern red oak), Acer rubrum (red maple), Kalmia latifolia (mountain laurel) and Rhododendron ‘Cunningham's White’ were dip‐inoculated with varying numbers of P. ramorum sporangia, and the total number of diseased and healthy leaves recorded following incubation at 20°C and 100% relative humidity. Calibration threshold estimates for obtaining 50% infected leaves based on linear analysis ranged from 36 to 750 sporangia/ml for the five hosts. Half‐life (LD50) estimates (the number of spores for which the per cent of diseased leaves reaches 50% of its total) from asymptotic regression analysis ranged from 94 to 319 sporangia/ml. Statistically significant differences (P = 0.0076) were observed among hosts in per cent infection in response to increased inoculum density. Inoculum threshold estimates based on studies with detached leaves were comparable to those obtained using whole plants. The results provide estimates of inoculum levels necessary to cause disease on these five P. ramorum hosts and will be useful in disease prediction and for development of pest risk assessments.

Seasonal patterns of light availability and light use of broadleaf evergreens in a deciduous forest understory: Potential mechanisms for expansion

In recent years, expansion of native and exotic evergreen shrubs into forest understories has been documented worldwide. Dense shrub thickets may interfere with tree establishment, suppress herbaceous cover, and contribute substantially to total standing crop of leaf biomass. Expansion may occur because evergreen shrubs exploit seasonal variations in irradiance and temperature that are characteristic of temperate understory environments. We quantified leaf-level light environment and photosynthetic activity of three sympatric broadleaf evergreens (Ilex opaca, Kalmia latifolia, and Myrica cerifera) in a deciduous forest understory in Charles City County,Virginia,USAin order to understand seasonal intra- and interspecific ranges of broadleaf evergreen physiology. Two species (K. latifolia and M. cerifera) represent a diverse taxonomic range within broadleaf evergreens, and often form expansive thickets. We measured parameters related to canopy structure (e.g., bifurcation ratio, leaf angle) and photosynthetic performance (e.g., electron transport rate or ETR, chlorophyll content), to identify potential mechanisms facilitating expansion. ETR varied both seasonally and among species. In summer, M. cerifera ETR was nearly double that ofI. opaca or K. latifolia. Additionally, leaf temperature enhanced photosynthetic capacity of expansive species. Evergreen species, though capable of fixing carbon throughout the year, often exhibit slow growth rates and low physiological activity. Yet, we observed that the range of evergreen physiological activity may be broader than previously recognized. Furthermore, our results indicate potential for changes in composition and expansion of the evergreen shrub layer by species that exhibit structural and physiological mechanisms advantageous for future rises in temperature.

Mountain laurel toxicosis in a dog

To describe a case of mountain laurel (Kalmia latifolia) toxicosis in a dog, including case management and successful outcome. A dog presented for vomiting, hematochezia, bradycardia, weakness, and ataxia, which did not improve with supportive treatment. Mountain laurel ingestion was identified as cause of clinical signs after gastrotomy was performed to remove stomach contents. Supportive treatment was continued and the dog made a full recovery. This report details a case of mountain laurel toxicosis in a dog, including management strategies and outcome, which has not been previously published in the veterinary literature.

First Report of Root Rot Caused by Phytophthora cinnamomi on Mountain Laurel (Kalmia latifolia) in Italy.

Kalmia latifolia L., common name Mountain Laurel, is an evergreen shrub that is becoming increasingly popular in gardens. It is also grown as a potted plant for its round flowers that range from light pink to white and occur in clusters in late spring. During July 2011, 3-year-old plants of K. latifolia 'Olympic Fire' showed extensive chlorosis and root rot on several commercial nurseries close to Maggiore Lake (Verbano-Cusio-Ossola Province) in northwestern Italy. Twigs wilted and died and leaves dropped, although in some cases, wilted leaves persisted on stems. The whole root system was affected with vascular tissues on the lower stem exhibiting brown discoloration, followed by plant death. The disease was severe and widespread, affecting 5% of approximately 3,500 plants. Tissue fragments of 1 mm2 were excised from the margins of the lesions and plated. A Phytophthora-like organism was consistently isolated on an oomycete-selective medium (BNPRA + HMI at 25 μg/ml) (4) after disinfesting root pieces for 1 min in a 1% NaOCl solution. The pathogen was identified based on morphological and physiological features as Phytophthora cinnamomi (2). Oogonia didn't form in single culture. On V8 agar, the microorganism was characterized by coenocytic coralloid hyphae, with spherical lateral and terminal swellings 23 to 46 (average 34) μm in diameter (n = 50), single or in clusters, and produced spherical, terminal chlamydospores 35 to 47 (average 40) μm in diameter (n = 50). No sporangia were produced after growing pure cultures in sterilized soil extracts nor were they produced on V8 agar. The internal transcribed spacer (ITS) region of the rDNA of a single isolate was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 898-bp segment showed a 99% homology with the sequence of P. cinnamomi (GU799638). The nucleotide sequence has been assigned the GenBank Accession No. JQ951607. Pathogenicity of one isolate obtained from infected plants was confirmed by inoculating 18-month-old plants of K. latifolia 'Olympic Fire'. The isolate was grown for 50 days in a mixture of 70:30 wheat/hemp kernels and then mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 v/v) at a rate of 3 g/l. One plant per 2-l pot was transplanted into the substrate and constituted the experimental unit. Five plants were inoculated. Noninoculated plants represented the control treatment and the trial was repeated once. All plants were kept in a greenhouse at 24 to 27°C. Two of five plants inoculated developed symptoms of chlorosis, wilting, and root rot after 70 days and remaining plants after about 80 days. P. cinnamomi was reisolated consistently from inoculated plants but not from controls that remained symptomless. To our knowledge, this is the first report of P. cinnamomi on K. latifolia in Italy and in Europe. The disease has been reported in the United States (3). The economic importance of the disease is uncertain because of the limited number of nurseries that grow this crop in Italy, although its importance could increase as the popularity of K. latifolia increases.

Host Plant Utilization Within Family Ericaceae by the Andromeda Lace Bug Stephanitis takeyai (Hemiptera: Tingidae)

This study examined host plant utilization by the Andromeda lace bug, Stephanitis takeyai Drake and Maa, within the family Ericaceae. The preferred host of S. takeyai is the Japanese pieris, Pieris japonica (Thunb.) D. Don ex G. Don, but it has been reported to exhibit host alternation and also to occur on other unrelated host plants. We examined the acceptability of ten landscape and fruit plants belonging to the family Ericaceae (Rhododendron calendulaceum, Rhododendron ‘Hampton Beauty’, Rhododendron ‘Autumn Empress’, Vaccinium arboreum, Vaccinium virgatum, Calluna vulgaris, Kalmia latifolia, Pieris floribunda, Pieris phillyreifolia and Pieris japonica ‘Temple Bells’) to S. takeyai. In no-choice tests adult survival did not vary significantly among the taxa. Highest leaf damage was recorded on P. japonica and R. calendulaceum, while slight damage was noted on V. arboreum and Rhododendron ‘Hampton Beauty’. Nymph emergence was observed in P. japonica, R. calendulaceum and Rhododendron ‘Hampton Beauty’. In multi-choice tests adult presence on leaves did not vary significantly except on day 9, when adults were more numerous on ‘Temple Bells’. Maximum leaf damage was recorded on P. japonica, ‘Temple Bells’. Several plants like Rhododendron and Vaccinium spp., which may not be favorable hosts, could serve as reservoirs for the pest.

Genes expressed in tissue-cultured seedlings of mountain laurel (Kalmia latifolia L.) with colonizing Streptomyces padanus AOK30

An endophytic actinomycete, Streptomyces padanus AOK30, is capable of protecting mountain laurel against infection by Pestalotiopsis sydowiana, a causal agent of Pestalotia disease, when applied to the seedling of the plant. In this study, suppression subtractive hybridization was used to identify genes differentially expressed in seedlings of mountain laurel after application of S. padanus AOK30. Subsequent dot hybridization with independent RNA from S. padanus-colonized and control plants identified nonredundant 180 cDNAs involving 71 and 109 clones, which were up- and downregulated after inoculation with the bacteria, respectively. Comparison of the sequences with databases revealed that a number of transcripts encoding proteins or enzymes that function directly in defense or stress response and regulatory proteins were regulated differentially in the seedlings with colonizing S. padanus AOK30. Semi-quantitative RT-PCR analysis for the selected genes demonstrated that inoculation of mountain laurel seedlings with S. padanus AOK30 increased expression of defense-related genes as well as distinct classes of glutathione S-transferase, although endochitinases were exclusively suppressed. These results clearly indicate that the S. padanus-colonizing seedlings likely initiate or prime plant defense responses toward pathogen infection. Selected genes were also differentially expressed in S. padanus-colonized seedlings, compared to those solely challenged with the fungal pathogen P. sydowiana. This approach will assist in efforts not only to understand the molecular basis of the enhanced tolerance and/or enhanced disease resistance of mountain laurel, but also to define a core set of genes during colonization or association with S. padanus AOK30.

Soil Calcium and Forest Birds: Indirect Links Between Nutrient Availability and Community Composition

Calcium is an important nutrient that can be limiting in many forest ecosystems, where acid deposition and other natural and anthropogenic activities have resulted in significant soil calcium depletion. Calcium’s critical role in physiological and structural processes and its limited mobility and storage in many organisms, make it a potential driver of ecosystem structure and function, but little is known about how changes in soil calcium affect community composition, especially in terrestrial vertebrates. The aim of this study was to establish relationships between the abundances of forest songbird species and soil calcium and to elucidate linking mechanisms by establishing simultaneous relationships with trophic and habitat variables. We measured soil calcium and pH, calcium-rich invertebrate abundances, vegetation, and songbird abundances at 14 interior forest sites across central Pennsylvania representing a range of soil calcium levels. Bird community composition varied with soil calcium and pH, with 10 bird species having the highest abundances in forests with high calcium soils, and five species having the highest abundances with low calcium soils. Bird species associated with low-calcium soils were associated with high densities of mountain laurel (Kalmia latifolia), an acid-loving shrub, whereas bird species associated with high-calcium soils were associated with high densities of saplings and high basal area of acid-sensitive tree species. Homogenization of soil conditions through land-use patterns and soil calcium depletion pose the risk of reducing the beta diversity of bird species across forest areas because community composition varied with soil calcium.

Phytophthora obscura sp. nov., a new species of the novel Phytophthora subclade 8d

A new Phytophthora species was detected (i) in the USA, infecting foliage of Kalmia latifolia, (ii) in substrate underneath Pieris, and (iii) in Germany in soil samples underneath Aesculus hippocastanum showing disease symptoms. The new species Phytophthora obscura sp. nov. is formally named based on phylogenetic analysis, host range, Koch’s postulates and morphology. Phytophthora obscura is homothallic with paragynous antheridia and semipapillate sporangia. It is genetically closely related to P. syringae and P. austrocedrae and together these three species define a new Phytophthora subclade 8d, with significant support for all genetic loci analysed including seven nuclear genes and the mitochondrial gene coxII. The morphological and ecological characteristics are very similar to P. syringae, and it is likely that P. obscura was not described earlier because it was identified as P. syringae. Artificial inoculations indicated that horse chestnut, kalmia, pieris and rhododendron might be hosts, and Koch’s postulates were confirmed for kalmia from which it was isolated. This pathogen was named after its elusive nature since it has to date rarely been detected in the US and Germany.