Mycorrhizal colonization of Hypericum perforatum L. (Hypericaceae) on adjacent serpentine and granite outcrops on the Deer Isles, Maine, USA

Given the paucity of literature on plant-fungal interactions on serpentine soils and limited investigation of serpentine geoecology in eastern North America, we examined mycorrhizal colonization of Hypericum perforatum from adjacent serpentine and granite outcrops on the Deer Isles, ME to determine whether plants were differentially colonized based on substrate. We coincided our sampling with three phenologic stages of H. perforatum (preflowering, flowering, postflowering) to determine possible differences in colonization based on plant phenology. The levels of mycorrhizal colonization in H. perforatum were not significantly different between serpentine and granite sites, while levels of colonization in postflowering plants were significantly higher than in those at preflowering and flowering stages

Adiantum viridimontanum, Aspidotis densa, Minuartia marcescens, and Symphyotrichum rhiannon: Additional Serpentine Endemics from Eastern North America

Serpentine outcrops around the world are known to harbor disproportionately high rates of plant endemism. Remarkable cases of serpentine endemism occur in New Caledonia and Cuba, with 3178 and 920 endemic taxa, respectively, found solely on serpentine. Despite the patchy occurrence of serpentine in eastern North America from Québec and Newfoundland south to Alabama, only one taxon, Cerastium velutinum var. villosissimum, has been broadly recognized as a serpentine endemic for the region. Based on reports in the literature, we suggest that Adiantum viridimontanum, Minuartia marcescens, and Symphyotrichum rhiannon be considered endemic to serpentine soils from the east coast of North America. Aspidotis densa, with several disjunct populations on and off serpentine in western North America, is known solely from serpentine soils where it occurs in eastern North America and should be considered endemic to the substrate there. The geobotany of eastern North America in general is poorly understood, and additional taxonomic studies on the region\u27s unique geologic substrates will likely yield further edaphic endemics

Advances in serpentine geoecology: A retrospective

(In absence of a text abstract the first paragraph of the paper is provided.) Serpentine habitats have long provided model settings for geoecological research (reviewed in Alexander et al. 2007, Brady et al. 2005, Brooks 1987, Kazakou et al. 2008, Kruckeberg 1984, Proctor and Woodell 1975, Raja-karuna et al 2009). Serpentine loosely refers to a broad group of minerals associated with the weathering of ultramafi c (high iron and magnesium-rich) rocks found along continental margins and orogenic belts. Soils associated with such rocks often differ from more widespread soils, being less fertile and having high concentrations of some heavy metals. The unique geochem-istry of serpentine soils generates habitats worldwide that are biologically unique, providing model settings for research on how geology and soils can shape the biotic world around us

Vascular plants of adjacent serpentine and granite outcrops on the Deer Isles, Maine, USA

We performed a comparative study of the vascular flora of a serpentine outcrop, Pine Hill, and that of a granite outcrop, Settlement Quarry, from Little Deer Isle and Deer Isle, respectively, Hancock County, Maine. We established four transects along a gradient from exposed to forested areas within each outcrop. Plants were recorded for presence and percent cover from circular plots along each transect. Soil and tissue samples were collected to examine soil-tissue elemental relations. One hundred thirty-two taxa were recorded from serpentine and 89 from granite. Fifty-seven taxa were shared by both sites. Species richness (α diversity) and diversity indices (Shannon-Weaver and Simpson) suggested significant differences between sites and within sites. Principle Component Analysis suggested substrates differed significantly between sites and between exposures within sites. Tissue analyses suggested intraspecific variation with respect to tissue elemental concentrations, especially in Achillea millefolium, Oenothera biennis, Prunus virginiana, Selaginella rupestris, Spiraea alba var. latifolia, and Vaccinium angustifolium. Serpentine populations of many taxa showed low tissue CaMg ratios (\u3c 1) and high Ni concentrations. Two-way ANOVA showed significant substrate × species effects for several elements, including those that typically characterize serpentine substrates (Ca, Mg, Cr, Ni), suggesting significant genetic variation within species with respect to substrate. Finally, we compared our species list for Pine Hill with a plant survey done at Pine Hill and five additional serpentine sites of Maine in 1977 and provide a list of 285 vascular plant taxa from 62 families for serpentine in Maine

The role of elevation and soil chemistry in the distribution and ion accumulation of floral morphs of Streptanthus polygaloides Gray (Brassicaceae), a Californian nickel hyperaccumulator

Background: The flora of serpentine/ultramafic soils provides an excellent model system for the study of natural selection in plant populations. Streptanthus polygaloides is a nickel hyperaccumulator that is endemic to serpentine soils in the Sierra Nevada of California, and has four floral morphs (yellow, purple, yellow-to-purple and undulate). Aims: We investigate three hypotheses: (1) the purple morph occurs in colder, wetter climates than the yellow morph; (2) tissue–soil ionic relationships differ among morphs; and (3) morphs occur on soils with differing elemental concentrations. Methods: We queried herbarium records to investigate patterns of occurrence among the yellow and purple floral morphs, and analysed soil and tissue samples from wild populations of all four morphs. Results: The purple morph inhabited serpentine outcrops with colder temperatures and greater precipitation levels than the yellow morph. Concentrations of elements in leaf tissue and rhizosphere soil differed little among populations of the morphs, but showed substantial within-site variation. Conclusions: Our results suggest that a climatic gradient may be responsible for divergence in floral colour among populations of S. polygaloides. Because of the large within-site variation in soil and tissue elemental concentrations, plants appear to have a varied physiological response to edaphic factors, regardless of morph membership

Impacts of Nutrient Enrichment on Native and Non-Native Plants in Serpentine Soil

Serpentine soil, derived from serpentinite, California’s state rock, is characterized by its harsh nature - due to its low levels of essential nutrients and exceptionally high levels of toxic heavy metals.In California, serpentine soils are characterized by high levels of plant endemism and rarity. Plants occurring in serpentine soil exhibit extreme tolerance of harsh soil conditions, and are typically out-competed in ‘normal’ soils due to the cost associated with physiological specialization. Atmospheric nutrient deposition is contributing to a greater invasion of non-native grass species on serpentine soils, outcompeting the native species and threatening them with local extinction. Our greenhouse study aims to explore the impact of nutrient enrichment on four species of annual grasses and herbs - Festuca microstachys and Plantago erecta as natives, and Avena fatua and Bromus hordeaceus as non-natives - growing together under a competitive environment. Our experiment monitored survival, growth, flowering time, reproductive effort and biomass of each species under the addition of nitrogen, phosphorus, nitrogen + phosphorus, and a control treatment. Each treatment was carried out in a tray containing three individuals of each species, for a total of twelve plants per tray, and six replicates of each treatment, for a total of twenty-four trays, all of which were grown within a greenhouse setting to recreate natural climate conditions. In an era where climate change and pollution are of serious concern with respect to biodiversity conservation, a study investigating native and non-native plant interactions on serpentine soils would provide useful information on how a prime aspect of climate change, atmospheric deposition of nutrients, can influence the last refuge for many of California’s rare and endemic plants. Knowledge gained from this study could be used for better management of biodiverse serpentine habitats in California

Little evidence for local adaptation to soils or microclimate in the postfire recruitment of three Californian shrubs

Background: Seedling recruitment following fire is an infrequent yet critical demographic transition for woody plants in Mediterranean ecosystems. Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape. Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes. Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local adaptation with respect to seedling recruitment in these environments. Seedlings of all species manifested lower survival and relative growth on serpentine soils regardless of seedling source, as well as a variety of other destination and source effects. Conclusions: The ability of these three species to recruit in new environments, such as in restoration settings or in response to shifting climates, is unlikely to be impeded by a need for seeds from sources that closely match their edaphic or topographic destination

Deblurring Filter Design Based on Fuzzy Regression Modeling and Perceptual Image Quality Assessment

Images captured by digital cameras are generally not perfect as image blurring is usually generated by camera motion through long hand-held exposure. Deblurring filters can be used to improve image quality by removing image blur. Prior to develop a deblurring filter, a simulator for image quality assessment is essential to optimize filter parameters. Although subjective image quality assessment (subjective IQA) is commonly used for evaluating the visual effect of digital images for a wide range of image processing applications, it is inconvenient to be implemented in real-time. Generally, statistical regression is used to generate a functional map to correlate the subjective IQA and the objective image quality metrics. However, it cannot address the uncertainty caused by human judgment during the subjective IQA. This paper first proposes a fuzzy regression method to develop the functional map that overcomes the limitation of statistical regression that cannot account for uncertainty introduced through human judgment. Based on the fuzzy regression models, the deblurring filter parameters can be optimized. Experimental results show that the satisfactory deblurring can be achieved on blurred images captured by a smartphone camera

Additional lichen records and mineralogical data from metal-contaminated sites in Maine

Geochemistry and mineralogy of rocks play important roles in the occurrence of individual lichen species and assembly of lichen communities. Whereas lichens of metal-enriched settings have been a focus of study for many decades, only a few such lichen inventories exist for North America. We reexamined the lichen biota of Pine Hill, a serpentine outcrop on Little Deer Isle, Maine and Callahan Mine, a copper-and zinc-enriched Superfund site in Brooksville, Maine by conducting additional field surveys and reexamining unidentified taxa from previous collections. To better characterize the substrates upon which the lichens were found, we conducted elemental analyses via x-ray fluorescence and inductively coupled plasma-mass spectrometry on rock samples collected at Pine Hill and recorded pH, electrical conductivity, and elemental concentrations via inductively coupled plasma mass spectrometry on soil samples from Callahan Mine. The re-investigation of lichens of the two metal-enriched sites resulted in the addition of 20 taxa to Pine Hill and 10 taxa to Callahan Mine. These include Dermatocarpon leptophyllodes, Placynthiella hyporhoda, Pyrenocarpon thelostomum, and Vezdaea acicularis, all recorded for the first time from New England. In addition, we report the first documented records since the late 19th to early 20th century for New England of Porocyphus coccodes, Sarcosagium campestre, and Steinia geophana, and the first such record for Maine for Coccocarpia palmicola. Stereocaulon condensatum and S. subcoralloides, both considered as rare in New England, were also collected from Callahan Mine

Biology of ultramafic rocks and soils: research goals for the future

At this, the 6th International Conference on Serpentine Ecology, it seems timely to review briefly the present status of the field and to project the needs for future research. Although a great deal of serpentine research was done prior to 1960, as summarized by Krause (1958) and discussed briefly by Brooks (1987), much of our progress in learning how serpentine geology affects plant and animal life occurred in the mid- to late 20th century. In that era, it was the landmark studies of several scientists worldwide that initiated a meteoric increase in published serpentine research. Key players in setting the stage for this burgeoning output included pioneers in Europe (e.g., John Proctor, Stan Woodell, Ornella Vergnano, and Olof Rune), North America (e.g., Herbert Mason, Robert Whittaker, Hans Jenny, Richard Walker, and Arthur Kruckeberg); and elsewhere (e.g., Robert Brooks, Alan Baker, Roger Reeves, and Tanguy Jaffré). All made notable contributions to understanding the “serpentine syndrome.” Despite the flourishing of serpentine studies in recent years, there is much “unfinished business.” After all, an axiom of science is that there is an unending quest for answers. In the many subdisciplines of geology and the soil and plant sciences, serpentine areas still hold mysteries— unsolved questions and challenges for the future. We now examine some of them, organized by the five major topic areas covered by the conference (Geology and Soils, Biota, Ecology and Evolution, Physiology and Genetics, and Applied Ecology), and point out how some of the contributions at the conference, and some that are included in this Proceedings Special Issue, address them