Geology topics

Wilfred B. Schofield

Publications and source records attributed to Wilfred B. Schofield.

8 recordsLinked to original sources

USGS2018

Liverworts from Attu Island, Near Islands, Aleutian Islands, Alaska (USA) with comparison to the Commander Islands (Russia)

The liverwort flora of Attu Island, the westernmost Aleutian Island in the United States, was studied to assess species diversity in the hyperoceanic sector of the northern boreal subzone. The field study was undertaken in sites selected to represent a spectrum of environmental variation, primarily within the eastern part of the island. Data were analyzed using our own collections on Attu Island, supplemented with information from published reports to compare bryophyte distribution patterns at three levels, the Northern Hemisphere, North America, the Commander Islands of Russia, and Alaska. A total of 112 liverworts were identified and a substantial number, 34 species (30%), were new reports from Attu Island and one was new to Alaska. Geographic elements dominating the flora included arctomontane (26%), arctoboreomontane (23%), montane (20%), and boreal (14%) species, while arctic species were almost absent (1%). The liverworts of the Attu Island-Commander Islands region were widespread species with over 70% circumpolar, or nearly circumpolar; nevertheless large gaps were present in some of their distributions with a floristic depression in liverwort distribution between Attu and the Commander Islands.

Alaska↗

USGS2010

Vegetation of eastern Unalaska Island, Aleutian Islands, Alaska

Plant communities of Unalaska Island in the eastern Aleutian Islands of western Alaska, and their relationship to environmental variables, were studied using a combined Braun-Blanquet and multivariate approach. Seventy relevés represented the range of structural and compositional variation in the matrix of vegetation and landform zonation. Eleven major community types were distinguished within six physiognomic–ecological groups: I. Dry coastal meadows: Honckenya peploides beach meadow, Leymus mollis dune meadow. II. Mesic meadows: Athyrium filix-femina – Aconitum maximum meadow, Athyrium filix-femina – Calamagrostis nutkaensis meadow, Erigeron peregrinus – Thelypteris quelpaertensis meadow. III. Wet snowbed meadow: Carex nigricans snowbed meadow. IV. Heath: Linnaea borealis – Empetrum nigrum heath, Phyllodoce aleutica heath, Vaccinium uliginosum – Thamnolia vermicularis fellfield. V. Mire: Carex pluriflora – Plantago macrocarpa mire. VI. Deciduous shrub thicket: Salix barclayi – Athyrium filix-femina thicket. These were interpreted as a complex gradient primarily influenced by soil moisture, elevation, and pH. Phytogeographical and syntaxonomical analysis of the plant communities indicated that the dry coastal meadows, most of the heaths, and the mire vegetation belonged, respectively, to the widespread classes Honckenyo–Elymetea, Loiseleurio–Vaccinietea, and Scheuchzerio–Caricetea, characterized by their circumpolar and widespread species. Amphi-Beringian species were likely diagnostic of amphi-Beringian syntaxa, many of these yet to be described.

Alaska↗

USGS2006

Vascular flora of Izembek National Wildlife Refuge, westernmost Alaska Peninsula, Alaska

The vascular flora of Izembek National Wildlife Refuge (NWR), where few previous collections had been reported, was collected and recorded at sites selected to represent the totality of environmental variation. A total of 349 species (339 native and 10 introduced) was identified. To provide a comparative phytogeographic framework, we analyzed data from published reports that categorized vascular plant distribution patterns from a circumpolar, North American, and Alaskan perspective. The native flora of the Izembek NWR primarily includes species of circumpolar (38%), eastern Asian (23%), Eurasian (18%), and North American (13%) distribution. The most important longitudinal distributional classes in North America consist of transcontinental (62%) and extreme western species (31%). The annotated list of species in Izembek NWR expands the range of many species, filling a distributional gap in Hulte??n's Western Pacific Coast district. Forty notable range extensions are reported. The flora of Izembek NWR is primarily made up of boreal species and lacks many of the species considered to be Arctic. Comparison with the Raunkiaer life-form spectrum similarly points to the boreal.

Rhodora↗

USGS2004

Phytosociological study of the dwarf shrub heath of Simeonof Wilderness, Shumagin Islands, Southwestern Alaska

The maritime dwarf shrub heath vegetation of the Northern Pacific, Simeonof Island, Shumagin Islands, Southwestern Alaska, was studied according to the Braun-Blanquet approach. Based on 30 releve??s of 16 m2 that include vascular plants, bryophytes, and lichens, two new associations could be described belonging to the class Loiseleurio-Vaccinietea (order Rhododendro-Vaccinietalia): Rubo-Empetretum nigri and Carici-Empetretum nigri. The wind-sheltered Rubo-Empetretum nigri (alliance Phyllodoco-Vaccinion) mainly occurs in the lowlands on level terrain or sloping sites at lower foot slopes of mountains on deeper, mesic soil; this association is the zonal vegetation of the lowlands. Boreal, widespread and amphi-Beringian species are prominent in the distribution-type spectrum of the vascular plants. Two variants of Rubo-Empetretum nigri are described. A Geranium erianthum variant occurs on south-facing slopes and is rich in vascular plants species. A Plagiothecium undulatum variant is restricted to northern exposures and is rich in bryophytes and lichens. A Carici-Empetretum nigri (alliance Loiseleurio-Diapension) occurs on shallow soil on wind exposed sites at higher elevations in the mountains. It is very rich in lichen species of arctic-alpine distribution. Canonical correspondence analysis (CCA) suggests that altitude, nutrient content of the soil and exposition are the most important differential ecological factors. Soil depth, total carbon and nitrogen content, plant available phosphorus and all other measured cation contents are higher in Rubo-Empetretum than in Carici-Empetretum. Literature comparisons confirm the occurrence of both associations in other areas on the Southwest Alaska Peninsula and Aleutian Islands. Presumably both associations have an amphi-Beringian distribution. The syntaxonomy of boreal-montane dwarf shrub heaths and synecological aspects are briefly discussed. ?? 2004 Gebru??der Borntraeger.

Phytocoenologia↗

USGS2004

Bryophytes from Simeonof Island in the Shumagin Islands, southwestern Alaska

Simeonof Island is located south of the Alaska Peninsula in the hyperoceanic sector of the middle boreal subzone. We examined the bryoflora of Simeonof Island to determine species composition in an area where no previous collections had been reported. This field study was conducted in sites selected to represent the spectrum of environmental variation within Simeonof Island. Data were analyzed using published reports to compare bryophyte distribution patterns at three levels, the Northern Hemisphere, North America, and Alaska. A total of 271 bryophytes were identified: 202 mosses and 69 liverworts. The annotated list of species for Simeonof Island expands the known range for many species and fills distribution gaps within Hultén's Western Pacific Coast district. Maps and notes on the distribution of 14 significant distribution records are presented. Compared with bryophyte distribution in the Northern Hemisphere, the bryoflora of Simeonof Island primarily includes taxa of boreal (55%), temperate (20%), arctic (10%), and cosmopolitan (8%) distribution; 6% of the moss flora are western North America endemics. A description of the bryophytes present in the vegetation and habitat types is provided as is a quantitative analysis of the most frequently occurring bryophytes in crowberry heath.

Alaska↗

USGS2002

Bryophytes from Tuxedni Wilderness area, Alaska

The bryoflora of two small maritime islands, Chisik and Duck Island (2,302 ha), comprising Tuxedni Wilderness in western lower Cook Inlet, Alaska, was examined to determine species composition in an area where no previous collections had been reported. The field study was conducted from sites selected to represent the totality of environmental variation within Tuxedni Wilderness. Data were analyzed using published reports to compare the bryophyte distribution patterns at three levels, the Northern Hemisphere, North America, and Alaska. A total of 286 bryophytes were identified: 230 mosses and 56 liverworts. Bryum miniatum, Dichodontium olympicum, and Orthotrichum pollens are new to Alaska. The annotated list of species for Tuxedni Wilderness expands the known range for many species and fills distribution gaps within Hulte??n's Central Pacific Coast district. Compared with bryophyte distribution in the Northern Hemisphere, the bryoflora of Tuxedni Wilderness primarily includes taxa of boreal (61%), montane (13%), temperate (11%), arctic-alpine (7%), cosmopolitan (7%), distribution; 4% of the total moss flora are North America endemics. A brief summary of the botanical exploration of the general area is provided, as is a description of the bryophytes present in the vegetation and habitat types of Chisik and Duck Islands.

Alaska↗

USGS2001

Lichens from St. Matthew and St. Paul Islands, Bering Sea, Alaska

One hundred thirty-nine taxa of lichens including two lichen parasites are reported from St. Matthew and St. Paul Islands in the Bering Sea. Caloplaca lithophila is new to Alaska. Wide-ranging arctic-alpine and boreal species dominate the lichens; a coastal element is moderately represented, while amphi-Beringian species form a minor element. In comparison with St. Paul Island, St. Matthew Island is richer in arctic-alpine species.

Alaska↗

USGS2000

Lichens of Izembek National Wildlife Refuge, westernmost Alaska Peninsula

One hundred eighty-two taxa of lichens including two lichen parasites are reported from Izembek National Wildlife Refuge on the tip of the Alaska Peninsula. Metasphaeria tartarina is new to North America; Scoliciosporum umbrinum is new to Alaska. Wide-ranging, arctic-alpine, and boreal species dominate the lichen flora; a coastal element is moderately represented, while amphi-Beringian species form a minor element. Epigeic lichen abundance is described along a lowland to alpine mesotopographic gradient selected to represent major landscape variation in the refuge. Of six major community types identified, three had significant lichen components.

Alaska↗