Life Sciences Commons^™

Lichens Of Ultramafic Rocks: A Multidisciplinary Approach To Understanding The Ecology Of An Understudied Organism In A Well-Studied System, Michael Mulroy

Master's Theses

Lichens are among the most prominent and successful life forms of metal-rich habitats, including ultramafic rocks and soils; however, research on lichens of ultramafic habitats is limited, especially on the North American continent. A review of the published literature on lichens of ultramafic substrates in North America yielded a total of 437 lichen species reported from ultramafic rocks and soils. Lichen assemblages of ultramafic substrates vary in composition and are dominated by acidophytic (low pH preferring) taxa with a minor, but consistent, basiphytic (high pH preferring) component. Species lists from ultramafic habitats in different geographic regions varied widely, suggesting that …

Nickel Speciation, Microbial Community Structure, And Chemical Attributes In The Rhizosphere Of Nickel Hyperaccumulating And Non-Accumulating Plants Growing In Serpentine Soils, James W. Morris

Theses and Dissertations--Plant and Soil Sciences

Serpentine soils are formed from weathering of serpentinite, the ultramafic parent material that provides serpentine soils with their unique identity. Weathering of serpentinite results in a plethora of edaphic factors that impose strong selection pressures on plant life, with high magnesium (Mg) to calcium (Ca) ratio, low fertility, and high levels of geologically derived metals such as cobalt (Co), chromium (Cr), and nickel (Ni). Appropriately, plant life on serpentine soils is often specialized, sparse, and endemic which in turn affects the ecosystems that develop on serpentine soils from the landscape scale down to the physiology of their inhabitants. At the …

Plant-Pollinator Associations In An Eastern Serpentine Savannah And The Effects Of Overbrowsing, Allyson Richins

Theses and Dissertations

Chapter 1: Native plant response to deer overbrowsing in a serpentine savannah

Plants are particularly vulnerable to physical disturbance in low productivity areas, due to a high cost of replacing lost plant tissue. In the eastern United States, serpentine grasslands are fragmented ecosystems with high concentrations of rare endemic plant species, low concentrations of soil nutrients, and uncontrolled deer overpopulation. This study assessed functional responses of native angiosperms in a rare eastern serpentine savannah to selective deer browsing. Plant count, flower count, floral area, vegetative area, and plant height of 10 serpentine plant species were compared inside and outside of …

Influence Of Soil Water Content And Soil Amendments On Trace Metal Release And Seedling Growth In Serpentine Soil, Viraj Gunarathne, Nishanta Rajakaruna, Udaya Gunarathne, Jayanta Kumar Biswas, Zach A. Raposo, Meththika Vithanage

Biological Sciences

This study was conducted to evaluate the synergistic effects of organic amendments and soil water status on trace metal release from serpentine soil.

Impacts Of Nutrient Enrichment On Native And Non-Native Plants In Serpentine Soil, Amber R. Williams, Mary Devlin, N. Rajakaruna

STAR Program Research Presentations

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 …

Inducing Ni Sensitivity In The Ni Hyperaccumulator Plant Alyssum Inflatum Nyárády (Brassicaceae) By Transforming With Cax1, A Vacuolar Membrane Calcium Transporter, Rasoul Ghasemi, Hoorieh Share, Roza Sharif, Robert S. Boyd, Nishanta Rajakaruna

Biological Sciences

The importance of calcium in nickel tolerance was studied in the nickel hyperaccumulator plant Alyssum inflatum by gene transformation of CAX1, a vacuolar membrane transporter that reduces cytosolic calcium. CAX1 from Arabidopsis thaliana with a CaMV35S promoter accompanying a kanamycin resistance gene was transferred into A. inflatum using Agrobacterium tumefaciens. Transformed calli were subcultured three times on kanamycin-rich media and transformation was confirmed by PCR using a specific primer for CAX1. At least 10 callus lines were used as a pool of transformed material. Both transformed and untransformed calli were treated with varying concentrations of either calcium (1–15 mM) or …

Sympatric Serpentine Endemic Monardella (Lamiaceae) Species Maintain Habitat Differences Despite Hybridization, Kathleen M. Kay, Suzie Woolhouse, Brett A. Smith, Nathaniel S. Pope, Nishanta Rajakaruna

Biological Sciences

Ecological differentiation and genetic isolation are thought to be critical in facilitating coexistence between related species, but the relative importance of these phenomena and the interactions between them are not well understood. Here, we examine divergence in abiotic habitat affinity and the extent of hybridization and introgression between two rare species of Monardella (Lamiaceae) that are both restricted to the same serpentine soil exposure in California. Although broadly sympatric, they are found in microhabitats that differ consistently in soil chemistry, slope, rockiness and vegetation. We identify one active hybrid zone at a site with intermediate soil and above-ground characteristics, and …

Diversity And Functional Traits Of Lichens In Ultramafic Areas: A Literature Based Worldwide Analysis Integrated By Field Data At The Regional Scale, Sergio E. Favero-Longo, Enrica Matteucci, Paolo Giordani, Alexander G. Paukov, Nishanta Rajakaruna

Biological Sciences

While higher plant communities found on ultramafics are known to display peculiar characteristics, the distinguishability of any peculiarity in lichen communities is still a matter of contention. Other biotic or abiotic factors, rather than substrate chemistry, may contribute to differences in species composition reported for lichens on adjacent ultramafic and non-ultramafic areas. This work examines the lichen biota of ultramafics, at global and regional scales, with reference to species-specific functional traits. An updated world list of lichens on ultramafic substrates was analyzed to verify potential relationships between diversity and functional traits of lichens in different Köppen–Geiger climate zones. Moreover, a …

Lessons On Evolution From The Study Of Edaphic Specialization, Nishanta Rajakaruna

Biological Sciences

Plants adapted to special soil types are ideal for investigating evolutionary processes, including maintenance of intraspecific variation, adaptation, reproductive isolation, ecotypic differentiation, and the tempo and mode of speciation. Common garden and reciprocal transplant approaches show that both local adaptation and phenotypic plasticity contribute to edaphic (soil-related) specialization. Edaphic specialists evolve rapidly and repeatedly in some lineages, offering opportunities to investigate parallel evolution, a process less commonly documented in plants than in animals. Adaptations to soil features are often under the control of major genes and they frequently have direct or indirect effects on genes that contribute to reproductive isolation. …

Distribution And Ecotypic Variation Of The Invasive Annual Barb Goatgrass (Aegiolops Triuncialis) On Serpentine Soil, Kelly G. Lyons, A M. Shapiro, Mark W. Schwartz

Kelly G Lyons

Successful colonization of newly introduced species is driven by a multitude of factors and is highly dependent on the species. It has long been hypothesized that preadaptation and postestablishment natural selection of introduced species can facilitate their invasion; however, to date, limited research has been dedicated to these theories. In addition, although the correlation between establishment of invasive species and disturbance has been noted and widely studied, the susceptibility of undisturbed habitats to invasion remains unclear. In California, serpentine habitats are severe edaphic environments that have been relatively free of anthropogenic disturbance and nonindigenous species invasions. In this study, we …

Distribution And Ecotypic Variation Of The Invasive Annual Barb Goatgrass (Aegiolops Triuncialis) On Serpentine Soil, Kelly G. Lyons, A M. Shapiro, M. W. Schwartz

Kelly G Lyons

Successful colonization of newly introduced species is driven by a multitude of factors and is highly dependent on the species. It has long been hypothesized that preadaptation and postestablishment natural selection of introduced species can facilitate their invasion; however, to date, limited research has been dedicated to these theories. In addition, although the correlation between establishment of invasive species and disturbance has been noted and widely studied, the susceptibility of undisturbed habitats to invasion remains unclear. In California, serpentine habitats are severe edaphic environments that have been relatively free of anthropogenic disturbance and nonindigenous species invasions. In this study, we …

Vegetation Dynamics And Mesophication In Response To Conifer Encroachment Within An Ultramafic System, J. Burgess, K. Szlavecz, N. Rajakaruna, S. Lev, C. Swan

Biological Sciences

The biological, ecological, and evolutionary significance of serpentine habitats has long been recognised. We used an integrated physiochemical dataset combining plot spatial data with temporal data from tree cores to evaluate changes in soils and vegetation. Data suggest that this unique habitat is undergoing a transition, endangering local biodiversity and endemic plant species. The objective of this work was to analyse the vegetation dynamics of a xeric serpentine savanna located in the Mid-Atlantic, USA. We employed vegetation surveys of 32 10 × 15 m quadrats to obtain woody species composition, density, basal area, and developed a spatial physiochemical dataset of …

Ecotypic Differentiation Of Mid-Atlantic Quercus Species In Response To Ultramafic Soils, Jerry Burgess, Katalin Szlavecz, Nishanta Rajakaruna, Christopher Swan

Biological Sciences

Spatial heterogeneity of soil conditions combined with intraspecific variation confer site-specific edaphic tolerance, resulting in local adaptation and speciation. To understand the geoecological processes controlling community assembly of woodland tree species on serpentine and mafic soils, we investigated resource gradients and provenance (geographic area of propagule collection) as variables affecting typical representative upland oak (Quercus) species distribution. Accordingly, we conducted a year-long reciprocal transplant experiment in the greenhouse with serpentine and mafic soils, using seedlings of five oak species (Quercus marilandica, Q. stellata, Q. montana, Q. michauxii and Q. alba). All seedlings, regardless …

Immobilization And Phytotoxicity Reduction Of Heavy Metals In Serpentine Soil Using Biochar, I. Herath, P. Kumarathilaka, A. Navarantne, N. Rajakaruna, M. Vithanage

Biological Sciences

Purpose

Serpentine soils derived from ultramafic rocks release elevated concentrations of toxic heavy metals into the environment. Hence, crop plants cultivated in or adjacent to serpentine soil may experience reduced growth due to phytotoxicity as well as accumulate toxic heavy metals in edible tissues. We investigated the potential of biochar (BC), a waste byproduct of bioenergy industry in Sri Lanka, as a soil amendment to immobilize Ni, Cr, and Mn in serpentine soil and minimize their phytotoxicity.

Materials and methods

The BC used in this study was a waste byproduct obtained from a Dendro bioenergy industry in Sri Lanka. This …

Additional Lichen Records And Mineralogical Data From Metal-Contaminated Sites In Maine, Ian D. Medeiros, Alan M. Fryday, N. Rajakaruna

Biological Sciences

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 …

Little Evidence For Local Adaptation To Soils Or Microclimate In The Post-Fire Recruitment Of Three Californian Shrubs, Annette Bieger, Nishanta Rajakaruna, Susan Harrison

Biological Sciences

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 …

Edaphic Adaptation Maintains The Coexistence Of Two Cryptic Species On Serpentine Soils, Jenn M. Yost, Teri Barry, Kathleen M. Kay, Nishanta Rajakaruna

Biological Sciences

• Premise of the study: Divergent edaphic adaptation can contribute to reproductive isolation and coexistence between closely related species, yet we know little about how small-scale continuous edaphic gradients contribute to this phenomenon. We investigated edaphic adaptation between two cryptic species of California wildflower, Lasthenia californica and L. gracilis (Asteraceae), which grow in close parapatry on serpentine soil.

• Methods: We reciprocally transplanted both species into the center of each species’ habitat and the transition zone between species. We quantified multiple components of fitness and used aster models to predict fitness based on environmental variables. We sampled soil across the …

Ecological Strategies In California Chaparral: Interacting Effects Of Soils, Climate, And Fire On Specific Leaf Area, Brian Anacker, Nishanta Rajakaruna, David D. Ackerly, Susan Harrison, Jon Keeley, Michael Vasey

Biological Sciences

Background: High values of specific leaf area (SLA) are generally associated with high maximal growth rates in resource-rich conditions, such as mesic climates and fertile soils. However, fire may complicate this relationship since its frequency varies with both climate and soil fertility, and fire frequency selects for regeneration strategies (resprouting versus seeding) that are not independent of resource-acquisition strategies. Shared ancestry is also expected to affect the distribution of resource-use and regeneration traits.

Aims: We examined climate, soil, and fire as drivers of community-level variation in a key functional trait, SLA, in chaparral in California.

Methods: We quantified the phylogenetic, …

Moving Magnesium In Plant Cells, Brian M. Waters

Department of Agronomy and Horticulture: Faculty Publications

Magnesium (Mg) is among the most abundant mineral elements in plants, yet the knowledge of which genes control its accumulation in specific tissues and organelles lags behind that of many other mineral elements. Only in recent years has identification of important molecular players begun to take shape. In this issue of New Phytologist, Conn et al. (pp. 583–594) shed additional light on two Mg transporters that play important roles in accumulation of Mg in leaf cell vacuoles. Using subcellular-level ion measurements on leaves, gene expression measurements after single-cell sampling, a genetic approach, and clever use of calcium (Ca) and …

Distribution And Ecotypic Variation Of The Invasive Annual Barb Goatgrass (Aegiolops Triuncialis) On Serpentine Soil, Kelly G. Lyons, A M. Shapiro, M. W. Schwartz

Biology Faculty Research

Successful colonization of newly introduced species is driven by a multitude of factors and is highly dependent on the species. It has long been hypothesized that preadaptation and postestablishment natural selection of introduced species can facilitate their invasion; however, to date, limited research has been dedicated to these theories. In addition, although the correlation between establishment of invasive species and disturbance has been noted and widely studied, the susceptibility of undisturbed habitats to invasion remains unclear. In California, serpentine habitats are severe edaphic environments that have been relatively free of anthropogenic disturbance and nonindigenous species invasions. In this study, we …

A New Species Of Streptanthus (Brassicaceae) From Three Peaks In Lake County, California, Rebecca W. Dolan, Richard O'Donnell

Rebecca W. Dolan

Streptanlhus vernalis is a newly described species inhabiting serpentine rock outcrops in the Three Peaks area in Lake County, California. Morphological and allozyme data indicate that this taxon is related to the S. morrisonii complex.

The Nickel Hyperaccumulating Plants Of The Serpentines Of Turkey And Adjacent Areas: A Review With New Data, Roger D. Reeves, Nezaket Adigüzel

Turkish Journal of Biology

Botanical exploration of serpentine soils in Turkey and neighbouring countries has shown that the region includes at least 59 taxa capable of hyperaccumulating nickel (to >0.1% of plant dry weight). These hyperaccumulators belong to the Brassicaceae (Aethionema R.Br., Alyssum L., Bornmuellera Hausskn., Pseudosempervivum (Boiss.) Grossh. (Cochlearia L.), and Thlaspi L. s.l.) and the Asteraceae (Centaurea L.). We review present knowledge of the hyperaccumulators and provide additional data recently obtained. Some species are serpentine-endemic and invariably Ni hyperaccumulating; others show more complex distribution and Ni-accumulating behaviour. Many are good subjects for biochemical studies on the Ni-accumulation and sequestering processes. There is …

A New Species Of Streptanthus (Brassicaceae) From Three Peaks In Lake County, California, Rebecca W. Dolan, Richard O'Donnell

Scholarship and Professional Work - LAS

Streptanlhus vernalis is a newly described species inhabiting serpentine rock outcrops in the Three Peaks area in Lake County, California. Morphological and allozyme data indicate that this taxon is related to the S. morrisonii complex.

The Edaphic Factor And Patterns Of Variation In Lasthenia Californica (Asteraceae), Nishanta Rajakaruna, Bruce A. Bohm

Biological Sciences

Transectional studies of Lasthenia californica in the Jasper Ridge Biological Preserve (Stanford University) have documented the existence of two races (A and C) based upon flavonoid chemistry, achene morphology, allozymes, and flowering time differences. The two races coexist on a serpentine outcrop and have maintained a sharply defined pattern of distribution for a period of at least 15 yr. The present study has revealed significant differences in the physical and chemical features of the soils harboring the two races. Soils at the lower ends of the transects, where race A plants grow, have higher pH, cation exchange capacity, relative water …

An Essay: Geoedaphics And Island Biogeography For Vascular Plants, A. R. Kruckerberg

Aliso: A Journal of Systematic and Floristic Botany

"Islands" of discontinuity in the distribution of plants are common in mainland (continental) regions. Such discontinuities should be amenable to testing the tenets of MacArthur and Wilson's island biogeography theory. Mainland gaps are often the result of discontinuities in various geological attributes-the geoedaphic syndrome of topography, lithology and soils. To discover ifgeoedaphically caused patterns of isolation are congruent with island biogeography theory, the effects of topographic discontinuity on plant distributions are examined first. Then a similar inspection is made of discontinuities in parent materials and soils. Parallels as well as differences are detected, indicating that island biogeography theory may be …