Paleoecology of a Middle Wisconsin Deposit from Southern California

2002 ◽  
Vol 58 (3) ◽  
pp. 310-317 ◽  
Author(s):  
R. Scott Anderson ◽  
Mitchell J. Power ◽  
Susan J. Smith ◽  
Kathleen Springer ◽  
Eric Scott
Keyword(s):  
Southern California ◽  
Vegetation Type ◽  
High Elevation ◽  
Santa Barbara Basin ◽  
Modern Pollen ◽  
San Bernardino ◽  
Cooling Phase ◽  
High Alkalinity ◽  
Valley Site ◽  
Climatic Cooling

AbstractAnalysis of a buried deposit in the Diamond Valley of southern California has revealed well-preserved pollen, wood, and diatom remains. Accelerator mass spectrometry dates of 41,200±2100 and 41,490±1380 14C yr B.P. place this deposit in marine isotope stage 3. Diatoms suggest a shallow lacustrine environment. Pollen data suggest that several plant communities were present near the site, with grassland, scrub, chaparral, forest, and riparian communities represented. Comparison with modern pollen suggests similarities with montane forests in the nearby San Bernardino and San Jacinto ranges, indicating vegetation lowering by at least 900 m elevation and temperatures 4°–5°C cooler than today. An increase in high-elevation conifer pollen documents climatic cooling near the profile top. Early-profile diatoms are typical of warm water with high alkalinity and conductivity, whereas later diatoms suggest a higher flow regime and input of cooler water into the system. We suggest that the sequence is part of the cooling phase of an interstadial Dansgaard–Oeschger cycle. Records of the middle Wisconsin period are rare in southern California, but the Diamond Valley site is similar to records from Tulare Lake in the San Joaquin Valley and the ODP Site 893A record from Santa Barbara Basin. It is probable that the Diamond Valley assemblage is a local expression of a vegetation type widespread in the ranges and basins of southwestern California during the middle Wisconsin.

The effects of development, vegetation-type conversion, and fire on low-elevation Southern California spider assemblages

2017 ◽  
Author(s):  
Dakota M. Spear ◽  
Tessa A. Adams ◽  
Elise S. Boyd ◽  
Madison M. Dipman ◽  
Weston J. Staubus ◽  
...  
Keyword(s):  
Southern California ◽  
Vegetation Type ◽  
Type Conversion

Predicting spatial patterns of fire on a southern California landscape

2008 ◽  
Vol 17 (5) ◽  
pp. 602 ◽  
Author(s):  
Alexandra D. Syphard ◽  
Volker C. Radeloff ◽  
Nicholas S. Keuler ◽  
Robert S. Taylor ◽  
Todd J. Hawbaker ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Southern California ◽  
Vegetation Type ◽  
Fire Hazard ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Fuel Loading ◽  
Landscape Characteristics ◽  
Management Actions ◽  
Fire Ignitions

Humans influence the frequency and spatial pattern of fire and contribute to altered fire regimes, but fuel loading is often the only factor considered when planning management activities to reduce fire hazard. Understanding both the human and biophysical landscape characteristics that explain how fire patterns vary should help to identify where fire is most likely to threaten values at risk. We used human and biophysical explanatory variables to model and map the spatial patterns of both fire ignitions and fire frequency in the Santa Monica Mountains, a human-dominated southern California landscape. Most fires in the study area are caused by humans, and our results showed that fire ignition patterns were strongly influenced by human variables. In particular, ignitions were most likely to occur close to roads, trails, and housing development but were also related to vegetation type. In contrast, biophysical variables related to climate and terrain (January temperature, transformed aspect, elevation, and slope) explained most of the variation in fire frequency. Although most ignitions occur close to human infrastructure, fires were more likely to spread when located farther from urban development. How far fires spread was ultimately related to biophysical variables, and the largest fires in southern California occurred as a function of wind speed, topography, and vegetation type. Overlaying predictive maps of fire ignitions and fire frequency may be useful for identifying high-risk areas that can be targeted for fire management actions.

Redescription of the holotype of Bostrichoclerus bicornus Van Dyke, 1938, a rare species of the New World Tillinae Fauna (Coleoptera: Cleridae), with some taxonomic notes

Zootaxa ◽  
2019 ◽  
Vol 4544 (4) ◽  
pp. 548
Author(s):  
ALAN F. BURKE ◽  
JOHN M. JR. LEAVENGOOD ◽  
CLARKE H. SCHOLTZ ◽  
CATHERINE L. SOLE
Keyword(s):  
United States ◽  
Rare Species ◽  
Gulf Of California ◽  
Southern California ◽  
New World ◽  
Original Description ◽  
San Bernardino County ◽  
Southwest United States ◽  
Northwest Mexico ◽  
San Bernardino

Bostrichoclerus bicornus Van Dyke is known from southwest United States and northwest Mexico. To date, only two specimens have been captured: the holotype, collected on Isla Angel de la Guarda, in the Gulf of California, Mexico, and a second individual collected in San Bernardino County, California, United States. The original description of B. bicornus is brief and lacks any images. Considering its rarity, we present the redescription of this species based on the examination of the holotype and compare this taxon to similar genera of New World Tillinae. Images of the holotype and the Bostrichoclerus specimen collected in southern California are given. We conclude that B. bicornus is undoubtedly a member of the subfamily Tillinae with unclear intergeneric relations in the group. 

scholarly journals Smog Nitrogen and the Rapid Acidification of Forest Soil, San Bernardino Mountains, Southern California

2007 ◽  
Vol 7 ◽  
pp. 175-180 ◽  
Author(s):  
Yvonne A. Wood ◽  
Mark Fenn ◽  
Thomas Meixner ◽  
Peter J. Shouse ◽  
Joan Breiner ◽  
...  
Keyword(s):  
Southern California ◽  
Mediterranean Climate ◽  
Rapid Change ◽  
Soil Surface ◽  
Atmospheric Nitrogen ◽  
Wet Season ◽  
San Bernardino Mountains ◽  
San Bernardino ◽  
Fog Deposition ◽  
Very High

We report the rapid acidification of forest soils in the San Bernardino Mountains of southern California. After 30 years, soil to a depth of 25 cm has decreased from a pH (measured in 0.01 M CaCl2) of 4.8 to 3.1. At the 50-cm depth, it has changed from a pH of 4.8 to 4.2. We attribute this rapid change in soil reactivity to very high rates of anthropogenic atmospheric nitrogen (N) added to the soil surface (72 kg ha–1 year–1) from wet, dry, and fog deposition under a Mediterranean climate. Our research suggests that a soil textural discontinuity, related to a buried ancient landsurface, contributes to this rapid acidification by controlling the spatial and temporal movement of precipitation into the landsurface. As a result, the depth to which dissolved anthropogenic N as nitrate (NO3) is leached early in the winter wet season is limited to within the top ~130 cm of soil where it accumulates and increases soil acidity.

Sedimentary and Paleoclimatic Controls on Caddisfly (Insecta: Trichoptera) Assemblages during the Last Interglacial-to-Glacial Transition in Southern Ontario

1995 ◽  
Vol 43 (1) ◽  
pp. 90-105 ◽  
Author(s):  
Nancy E. Williams ◽  
Nicholas Eyles
Keyword(s):  
Species Richness ◽  
Sedimentary Facies ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Last Interglacial ◽  
Fair Weather ◽  
Southern Ontario ◽  
Valley Site ◽  
Climatic Cooling ◽  
Temperate River

AbstractSouthern Ontario, Canada, has late Pleistocene deposits that contain evidence for climatic cooling during the last interglacial/glacial transition and much of the succeeding Wisconsin glaciation. Fossils of lacustrine and riverine caddisflies (Insecta: Trichoptera) are abundant and well-preserved in these deposits. We examined 26 samples from the interglacial section exposed in the Don Valley Brickyard and compared their caddisfly assemblages with those recovered from the overlying early Wisconsin Scarborough Formation deposits at nearby Scarborough Bluffs. Fifty-one caddisfly taxa in 16 families were recovered from the Don Valley site. Fossil abundance and species richness appear related to the storm or fair-weather conditions inferred from the sedimentary facies. Caddisfly fossils were most abundant and species richness highest in fair-weather, peaty, rippled sands. Highest proportions of river species as opposed to lake species were recovered from sands (storm and fair-weather). Assemblages from both sites indicate the presence of a large and productive river flowing into ancestral Lake Ontario. However, the river assemblage appeared to be far more sensitive to environmental change than the relatively stable assemblage representing the thermally buffered lake. Warm temperate river species such as Hydropsyche bidens, Hydropsyche mississippiensis, Macrostemum carolina, and Potamyia flava are present in the lower Don samples but absent from the Scarborough Bluffs deposits, while indicators of cooler than present climatic conditions such as Arctopsyche Indogensis and Hagenella canadensis are present in the Scarborough Bluffs sediments but absent from the lower Don samples. For the interval from about 80,000 to 55,000 yr B.P., we infer a climatic cooling from temperature about 2°C warmer than present to about 3°C cooler than present.

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