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Post oak is a dominant species along the prairie border in the southcentral United States where upland forests gradually merge into the grasslands of the Southern Plains. These vegetation changes coincide with a sharp decrease in mean annual precipitation. Increment core studies at more than 50 sites from southern Texas to central Missouri indicate that old-growth post oak forests are still widespread, probably because these typically small, poorly formed trees were not systematically logged. Analysis of five tree-ring chronologies located across the precipitation gradient indicates that post oak radial growth is directly related to precipitation and inversely related to temperature for several months during and preceding the growing season. Post oak chronologies tend to become more variable and climate sensitive westward toward the prairie border, consistent with the decline in rainfall and the westward decrease in forest cover, species diversity, and tree size. This increase in climate sensitivity for post oak reflects the importance of declining rainfall amounts to the growth and probably to the distribution of upland deciduous forests on coarse-texture soils along the Southern Plains. The climate-explained growth variance for some post oak chronologies along the prairie border is very high, and is comparable to values typical for arid-site conifers. Selecting post oak sites from the prairie-forest transition zone or from other sites where moisture stress is frequent will provide a maximum of proxy climate information in the derived chronologies. [ABSTRACT FROM AUTHOR]

Analysis of a 58-day record in the Fall of 1972 from Niwot Ridge, Colorado Front Range reveals geomorphically significant differences in surficial bedrock temperatures between microsites and also between a meteorological screen and microsites. Bedrock surface daily maxima are extremely "flashy" and vary by 5 to 15°C between microsites and from 3 to 18°C between the screen and bedrock. Freeze-thaw cycle regimes exhibit freeze amplitudes and frequencies that indicate the need for careful reappraisal of the notion that freeze-thaw weathering is widespread. [ABSTRACT FROM AUTHOR]

The Fairfax line, surveyed in 1746 starts at the southern tip of western Maryland and extends 76.5 miles (123km), bearing S 46° E, to the headwaters of the Conway River in Madison County, Virginia. The forests of the Fairfax line can be divided into five map units, based on the presence or absence of ‘key’ species, which have significantly different woody floras. The forest units show a pattern of alternations with topography and underlying rock type which can be best explained by differences m substrate moisture. Although the common woody species appear in recurring groups, each species responds more or less independently to variation in topographic form, rock type, and direction of exposure. The surveyor's journal documents a large blowdown in the presettlement forests of the Appalachian Plateau, and witness tree data suggest that distribution patterns of the common woody species have changed little m more than two hundred years. [ABSTRACT FROM AUTHOR]

The coastal regions of the Pacific Northwest of the United States have a marine west-coast which in other parts of the world is associated with broadleaf forests of the middle latitudes. In the Pacific Northwest such forests are so limited in extent as well as in the number of species as to be negligible. Estimates indicate that in the area west of the Cascade crest the proportion of the broadleaf trees on a numerical basis amounts only 6 per cent of the entire forest. When broadleaf trees are compared with conifers on the basis of timber volume, their proportion sinks to utter insignificance; the estimated proportion being only 1 : 1000. The following is en enquiry into this absence of a forest type which under similar conditions elsewhere seems to represent the climax association. [ABSTRACT FROM AUTHOR]

Discusses the climatic and geographic influences on ancient forests and the lumber trade in the Mediterranean Basin. Type of vegetation whose common physiognomy reflects the prevailing climatic conditions; Location of the Mediterranean vegetation; Fluctuations in the life conditions of the region.