scholarly journals Ornithogenic vegetation: how significant has the seabird influence been on the Aleutian Island vegetation during the Holocene?

2021 ◽  
Author(s):  
Olesya Smyshlyaeva ◽  
Elena Severova ◽  
Olga Krylovich ◽  
Evgeniya Kuzmicheva ◽  
Arkady Savinetsky ◽  
...  
Keyword(s):  
Nitrogen Isotopes ◽  
Radical Change ◽  
Aleutian Islands ◽  
Coastal Vegetation ◽  
Aleutian Island ◽  
Pollen Concentration ◽  
The Holocene ◽  
Bird Colonies ◽  
Bird Guano ◽  
Seabird Colonies

We have studied the long- and short-term periods of seabird influence on coastal vegetation. In the Aleutian Islands during the Holocene, terrestrial predators were virtually absent; as a result, large seabird colonies thrived along the coasts or across entire islands. Bird guano enriches the soil with nitrogen, which can lead to the formation of highly modified ornithogenic (bird-formed) ecosystems. The vegetation of several Aleutian Islands has been reconstructed; however, only the vegetation on Carlisle Island had noticeable impact from the seabird guano. For more detailed investigation of bird influence, we conducted pollen analysis to reconstruct the 9,300-year-old vegetation dynamics of the coast of Shemya Island. From earlier studies of nitrogen isotopes in peat, we discovered that a large seabird colony existed on Shemya from 4600 to 2400 years ago, and birds also influenced coastal ecosystems between 1470–1160 and 810–360 years ago. In these sequences, the tundra dominated by Ericaceae dwarf shrubs initially spread on the coast. During a period of at least 2200-years nitrogen enrichment led to the development of herb meadows with a high presence of Apiaceae. After a noticeable reduction in seabird colonies due to human hunting, grass-meadows spread. During the late Holocene several hundred years of seabird impact led to an increase in abundance of indicator taxa, ferns and umbelliferous species, as well as in total pollen concentration, but this did not result in a radical change of dominants. In recent decades, due to the extinction of the bird colonies, heather communities have begun to spread on the Shemya coast. Also large ash emissions in the Aleutian Islands can lead to a decrease in pollen concentration even in peat located far from an eruption.

On the recorded motion of the S phase at Florissant*

1952 ◽  
Vol 42 (2) ◽  
pp. 145-154
Author(s):  
Ross R. Heinrich ◽  
Harry K. Haill
Keyword(s):  
S Phase ◽  
Central American ◽  
Aleutian Islands ◽  
Aleutian Island ◽  
South American ◽  
Wave Analysis ◽  
S Wave ◽  
Preferential Direction ◽  
Saint Louis ◽  
S Waves

Abstract The initial motions of the P and S phases have been tabulated from the original seismograms of sixty earthquakes which recorded at the Florissant station in the years 1927–1938. The epicenters of these earthquakes were within limited areas of the following regions: the Aleutian Islands, the west-central coast of South America, and Central America. The study indicates that the Florissant seismograms show a preferential direction of motion for both P and S waves in the recordings of certain earthquakes from selected regions. The data compiled on the S phase indicated that a majority of the Aleutian and South American earthquakes recorded a sharp impulsive initial northeast motion at Florissant. The Central American earthquakes studied recorded S phases of somewhat indefinite onset which did not exhibit a preferential motion as they were read. The results of the application of Neumann's method of S-wave analysis to the Saint Louis seismograms of two selected Aleutian Island earthquakes are presented and a brief discussion of some possible structural implications of the various data is given.

Spiritual Survival in the Arctic Atxam Taligisniikangis of the Aleutian Islands

2003 ◽  
Vol 47 (3) ◽  
pp. 9-31
Author(s):  
MaryGen Salmon
Keyword(s):  
World War Ii ◽  
Aleutian Islands ◽  
The Arctic ◽  
Aleutian Island ◽  
World War

Watching a gathering of Athabaskan, Yup'ik, Inupiaq, Tlingit/Haida, Siberian Yup'ik, and Sugpiaq dancers, musicians, and artists, the author wonders if “authentic” Native dance still exists in Alaska. This question is asked with the knowledge that these performances were reconstructed after the Aleutian Island peoples were severely stressed by internment during World War II.

scholarly journals Cyanobacterial and algal diversity in the vicinity of two different seabird colonies in Spitsbergen

2016 ◽  
Vol 37 (2) ◽  
pp. 269-288 ◽  
Author(s):  
Mirosława Pietryka ◽  
Dorota Richter ◽  
Jan Matuła
Keyword(s):  
Species Richness ◽  
Direct Influence ◽  
Uria Lomvia ◽  
Alle Alle ◽  
Rissa Tridactyla ◽  
Piscivorous Bird ◽  
Algal Assemblages ◽  
Bird Colonies ◽  
And Behavior ◽  
Seabird Colonies

AbstractThe aim of the study was to compare cyanobacterial and algal assemblages occurring in ornithocoprophilous habitats formed under the influence of two seabird colonies (mixed colony of piscivorousUria lomviaandRissa tridactylaand planktivorousAlle alle) nesting on the southwest side of Hornsund (Spitsbergen). Various influences of the bird colonies (e.g.surface trophy, treading) lead to the formation of ornithogenic habitats with quantitatively and qualitatively diverse cyanobacterial and algal assemblages. Only 6 species common to both habitats were identified, but due to their different proportions the similarity ended there. Cyanobacterial and algal assemblages of both ornithogenic habitats also react rather differently to the intensity of the bird colonies’ influence. The assemblages located directly beneath piscivorous bird nests were characterized by a larger number of species, which decreased the farther from the colony it was. Cyanobacterial and algal assemblages located directly next to planktivorous bird nests were species poor, but species richness increased at locations farther from their direct influence. The obtained results confirmed that bird colonies characterized by different diet and behavior influenced the formation of two separate, quantitatively and qualitatively different cyanobacterial and algal assemblages. Species such asEucapsissp.,Gleocapsopsissp.,Gloeothecesp.,Woronichiniasp.,Hematococcussp. were characteristic for algae and cyanobacteria assemblages in the vicinity of piscivorous bird colonies, whereasAphanocapsasp.,Gloeothecesp.,Komvophoron minutum,Pseudanabaenasp.,Gloeocystissp. 2 occurred in the vicinity of planktivorous bird colonies.

scholarly journals The Holocene paleoenvironment in the Serra Velha region, RS, Brazil through a study of plant succession

2001 ◽  
Vol 28 (2) ◽  
pp. 245 ◽  
Author(s):  
MÁRCIA MIKLOSKI GRALA ◽  
MARIA LUISA LORSCHEITTER
Keyword(s):  
Significant Influence ◽  
Coastal Plain ◽  
Rain Forest ◽  
Rio Grande ◽  
Plant Succession ◽  
Coastal Vegetation ◽  
Atlantic Rain Forest ◽  
Rio Grande Do Sul ◽  
Herbaceous Vegetation ◽  
The Holocene

Palynological studies in the marsh forest of Serra Velha (29º36’S – 51º38’W), Rio Grande do Sul, Brazil, detected a plant succession through hydrosere from a water body already somewhat filled up by herbaceous vegetation at 9800 ± 90 yr BP. The climatic amelioration at the beginning of the Holocene accentuated the filling up process. Later, between 7800 – 7280 ± 60 yr BP, a short phase of significant influence of the forest over the marsh occurred. A new significant expansion of the forest, beginning at about 6000 yr BP took place. This gave rise to the present forest which is represented by many species of the Atlantic rain forest. Compared to the already existing palynological data about the Coastal Plain, it becomes evident that the present Serra Velha forest is older, which seems to indicate the importance of the foothill forests of Serra Geral in forming the present coastal vegetation in Rio Grande do Sul.

scholarly journals The Annual Migration Cycle of Emperor Geese in Western Alaska

ARCTIC ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 23 ◽  
Author(s):  
Jerry W. Hupp ◽  
Joel A. Schmutz ◽  
Craig R. Ely
Keyword(s):  
Coastal Region ◽  
Aleutian Islands ◽  
Aleutian Island ◽  
Commander Islands ◽  
Long Distance ◽  
Alaska Peninsula ◽  
Winter Distribution ◽  
Wintering Areas ◽  
Satellite Transmitters ◽  
The Bering Sea

Most emperor geese (Chen canagica) nest in a narrow coastal region of the Yukon-Kuskokwim Delta (YKD) in western Alaska, but their winter distribution extends more than 3000 km from Kodiak Island, Alaska, to the Commander Islands, Russia. We marked 53 adult female emperor geese with satellite transmitters on the YKD in 1999, 2002, and 2003 to examine whether chronology of migration or use of seasonal habitats differed among birds that wintered in different regions. Females that migrated relatively short distances (650–1010 km) between the YKD and winter sites on the south side of the Alaska Peninsula bypassed autumn staging areas on the Bering Sea coast of the Alaska Peninsula or used them for shorter periods (mean = 57 days) than birds that made longer migrations (1600–2640 km) to the western Aleutian Islands (mean = 97 days). Alaska Peninsula migrants spent more days at winter sites (mean = 172 days, 95% CI: 129–214 days) than western Aleutian Island migrants (mean = 91 days, 95% CI: 83–99 days). Birds that migrated 930–1610 km to the eastern Aleutian Islands spent intermediate intervals at fall staging (mean = 77 days) and wintering areas (mean = 108 days, 95% CI: 95–119 days). Return dates to the YKD did not differ among birds that wintered in different regions. Coastal staging areas on the Alaska Peninsula may be especially important in autumn to prepare Aleutian migrants physiologically for long-distance migration to winter sites, and in spring to enable emperor geese that migrate different distances to reach comparable levels of condition before nesting.

S-wave studies of earthquakes of the North Pacific, Part II: Aleutian Islands

1963 ◽  
Vol 53 (1) ◽  
pp. 59-77
Author(s):  
William Stauder ◽  
Agustin Udias
Keyword(s):  
Aleutian Islands ◽  
Aleutian Island ◽  
Stress System ◽  
S Wave ◽  
The North ◽  
Double Couple ◽  
First Motion ◽  
Good Determination ◽  
The North Pacific

Abstract The polarization of the S wave at stations distributed azimuthally about the source is examined for each of twenty-five Aleutian Island earthquakes. A combination of data from the first motion of P and from the polarization of S is then used to study the focal mechanisms of the earthquakes. This combination of P and S wave data is found to make possible a good determination of the focal mechanism in cases where data from the first motion of P alone do not suffice. The earthquakes are divided into three groups according to three basic patterns of S wave polarization. The first group (fourteen earthquakes) corresponds to a double couple. The second group (five earthquakes) and the third group (six earthquakes) are conformable to conjugate shears and may therefore be explained by single couple sources of opposite moment, respectively. It is shown that a uniform principal stress system predominates in the region and that the axis of greatest compressive stress is normal to the trend of the island arc.

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