Climate and the distribution of C4 grasses along the Atlantic and Pacific coasts of North America

2001 ◽  
Vol 79 (4) ◽  
pp. 474-486 ◽  
Author(s):  
Cindy SM Wan ◽  
Rowan F Sage
Keyword(s):  
North America ◽  
Minimum Temperature ◽  
Malic Enzyme ◽  
Pacific Coast ◽  
Atlantic Coast ◽  
Annual Precipitation ◽  
Grass Species ◽  
Mean Annual Precipitation ◽  
Exotic Grasses ◽  
The Pacific

In this study, relationships between temperature, precipitation, and the percentage of C4 grasses in local grass floras from the Atlantic and Pacific coastal regions of North America were examined. The proportion of C4 species in a local grass flora increased as latitude decreased on both coasts. At a given latitude, the C4 percentage on the Atlantic coast was higher than the Pacific coast. This difference was related to the Atlantic coast having greater July minimum temperatures than Pacific coast locations of similar latitude. Linear regression analysis showed that the proportion of C4 species in a local flora was positively associated with July minimum temperature on both coasts. The regression line between July minimum temperature and C4 representation was similar for each coast, indicating growth-season temperature has a similar control over C4 presence on the two coasts. Proportionally more of the annual precipitation fell in midsummer on the Atlantic than the Pacific coast, but this difference in the seasonal occurrence of precipitation did not alter the relationship between July minimum temperature and the contribution of C4 grass species to local floras. The Atlantic coast locations with the most precipitation had the highest C4 grass occurrence, indicating aridity alone did not increase the C4 representation in a grass flora. On both coasts, the proportion of NADP-malic enzyme C4 species in local C4 grass floras was positively correlated with mean annual precipitation; however, at equivalent percentages of NADP-malic enzyme subtype occurrence, precipitation levels were substantially lower on the Pacific than Atlantic coast. The trend between latitude and the percentage of C4 species in exotic grass floras was similar to the trend between latitude and the percentage of all C4 grasses in an entire grass flora. Thus, the C4 pathway appears to play no obvious role in enhancing the invasibility of exotic grasses in North America.Key words: bioinvasions, biogeography, C4 photosynthesis, C4 subtype, Poaceae, photosynthesis.

Summary of Coastal Geologic Evidence for past Great Earthquakes at the Cascadia Subduction Zone

1995 ◽  
Vol 11 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Brian F. Atwater ◽  
Alan R. Nelson ◽  
John J. Clague ◽  
Gary A. Carver ◽  
David K. Yamaguchi ◽  
...  
Keyword(s):  
British Columbia ◽  
North America ◽  
Subduction Zone ◽  
Forest Soils ◽  
Pacific Coast ◽  
Cascadia Subduction Zone ◽  
Level Change ◽  
The Past ◽  
The Pacific ◽  
Juan De Fuca

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a few centuries to about one thousand years.

scholarly journals MIS 5e sea-level history along the Pacific Coast of North America

2021 ◽  
Author(s):  
Daniel R. Muhs
Keyword(s):  
North America ◽  
Sea Level ◽  
Baja California ◽  
Pacific Coast ◽  
Level Indicator ◽  
Sequence Of Events ◽  
Marine Terraces ◽  
The Pacific ◽  
Mis 5E ◽  
Good Agreement

Abstract. The primary last interglacial, marine isotope substage (MIS) 5e records on the Pacific Coast of North America, from Washington (USA) to Baja California Sur (Mexico), are found in the deposits of erosional marine terraces. Warmer coasts along the southern Golfo de California host both erosional marine terraces and constructional coral reef terraces. Because the northern part of the region is tectonically active, MIS 5e terrace elevations vary considerably, from a few meters above sea level to as much as 70 m above sea level. The primary paleo-sea level indicator is the shoreline angle, the junction of the wave-cut platform with the former sea cliff, which forms very close to mean sea level. Most areas on the Pacific Coast of North America have experienced uplift since MIS 5e time, but the rate of uplift varies substantially as a function of tectonic setting. Chronology in most places is based on uranium-series ages of the solitary coral Balanophyllia elegans (erosional terraces) or the colonial corals Porites and Pocillopora (constructional reefs). In areas lacking corals, correlation to MIS 5e can sometimes be accomplished using amino acid ratios of fossil mollusks, compared to similar ratios in mollusks that also host dated corals. U-series analyses of corals that have experienced largely closed-system histories range from ~124 to ~118 ka, in good agreement with ages from MIS 5e reef terraces elsewhere in the world. There is no geomorphic, stratigraphic, or geochronology evidence for more than one high-sea stand during MIS 5e on the Pacific Coast of North America. However, in areas of low uplift rate, the outer parts of MIS 5e terraces apparently were re-occupied by the high-sea stand at ~100 ka (MIS 5c), evident from mixes of coral ages and mixes of molluscan faunas with differing thermal aspects. This sequence of events took place because glacial isostatic adjustment processes acting on North America resulted in regional high-sea stands at ~100 ka and ~80 ka that were higher than is the case in far-field regions, distant from large continental ice sheets. During MIS 5e time, sea surface temperatures (SST) off the Pacific Coast of North America were higher than is the case at present, evident from extralimital southern species of mollusks found in dated deposits. Apparently no wholesale shifts in faunal provinces took place, but in MIS 5e time, some species of bivalves and gastropods lived hundreds of kilometers north of their present northern limits, in good agreement with SST estimates derived from foraminiferal records and alkenone-based reconstructions in deep-sea cores. Because many areas of the Pacific Coast of North America have been active tectonically for much or all of the Quaternary, many earlier interglacial periods are recorded as uplifted, higher elevation terraces. In addition, from southern Oregon to northern Baja California, there are U-series-dated corals from marine terraces that formed ~80 ka, during MIS 5a. In contrast to MIS 5e, these terrace deposits host molluscan faunas that contain extralimital northern species, indicating cooler SST at the end of MIS 5. Here I present a standardized database of MIS 5e sea-level indicators along the Pacific Coast of North America and the corresponding dated samples. The database is available in Muhs (2021)  [https://doi.org/10.5281/zenodo.5557355].

scholarly journals Framing "Nova Albion": Marking possession in Richard Hakluyt’s The Principal Navigations, Voyages, Traffiques and Discoveries of the English Nation

Sederi ◽  
2014 ◽  
pp. 47-68
Author(s):  
Colm MacCrossan
Keyword(s):  
North America ◽  
Pacific Coast ◽  
The Pacific ◽  
Sir Walter Ralegh ◽  
History Of ◽  
Territorial Claims

This article examines the textual framing of a cluster of items in Richard Hakluyt’s The Principal Navigations, Voyages, Traffiques and Discoveries of the English Nation (1598-1600) relating to the area on the Pacific coast of North America that Francis Drake named “Nova Albion.” Contextualised in relation to the colonial programmes of Sir Humphrey Gilbert and Sir Walter Ralegh, it explores how a variety of editorial techniques combine to encourage a particular understanding of the history of exploration in this region that privileges English territorial claims over those of Spain. What is revealed is a delicate negotiation of the tensions raised by Hakluyt’s use of pre-existing, mainly non-English materials to attempt to legitimise Drake’s actions by aligning them with the Spanish conquistadorial tradition, while at the same time down-playing the extent and significance of previous Spanish activity in that region.

TWO NEW MEXICAN ISOTOGASTRURA (COLLEMBOLA: ISOTOGASTRURIDAE)

1998 ◽  
Vol 130 (2) ◽  
pp. 195-199 ◽  
Author(s):  
José G. Palacios-Vargas ◽  
Jean-Marc Thibaud
Keyword(s):  
New Species ◽  
Pacific Coast ◽  
Atlantic Coast ◽  
New Mexican ◽  
The Pacific ◽  
Two New Species

AbstractTwo new species of Isotogastrura, one from the Pacific coast and one from the Atlantic coast, are described: Isotogastrura ahuizotli sp.nov. and Isotogastrura veracruzana sp.nov. A key for the five species known at present is included.

Distribution patterns of disjunct and endemic vascular plants in the interior wetbelt of northwest North AmericaThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.

Botany ◽  
2010 ◽  
Vol 88 (4) ◽  
pp. 409-428 ◽  
Author(s):  
Curtis R. Björk
Keyword(s):  
Vascular Plants ◽  
Distribution Patterns ◽  
South Coast ◽  
Ice Age ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
North Coast ◽  
The Pacific ◽  
Inland Northwest ◽  
Wet Climate

A region of contrastively wetter and milder climate occurs in inland northwest North America, separated from similar climates of the Pacific coast by 200–400 km. Researchers have long noted that numerous vascular plants divide their ranges between the interior wetbelt and coastal regions, although many such disjunctions have hitherto gone undocumented. Here I summarize all vascular plants shared between coastal and interior wetbelt regions, disjunct by at least 200 km. These disjunct taxa are assigned to north-coast and south-coast lists according to whether the coastal portions of the ranges occur primarily north or south of the southern limits of maximum continental glaciation. A list of interior wetbelt endemic taxa is also presented, focusing on those that occur at forested elevations. Presence/absence for coastal disjunct and endemic taxa were assigned to grid of 1° × 1° latitude–longitude cells. Using this grid, concentrations of disjunct and endemic taxa were detected, and total values per cell were tested in linear regression for a relationship to mean annual precipitation. In total, 116 coastal disjunct taxa were detected, 31 of them north-coastal and 85 south-coastal. Interior wetbelt endemic and subendemic taxa total 95, and of these, 46 were found primarily at forested elevations. North-coast taxa were found over a wide latitudinal range both north and south of the glacial limits, and their distribution had a weak positive relationship with annual precipitation. South-coast and endemic taxa were found mostly south of the glacial limits, and their distribution did not correlate to annual precipitation. The greatest concentrations of south coastal disjunct and endemic taxa occurred in the Clearwater region of north-central Idaho; a region noted by previous researchers to be a likely ice-age refugium for wet-climate dependent plants and animals. Inferences are made from these patterns, both for biogeographical understanding of the roles played by the interior wetbelt and some regions connecting to the coast, as well as for preservation of biodiversity and ecosystem continuity.

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