Knobcone Pine is essentially a separate one back into the Pliocene, 

 a geological period which began about 10 million years ago. In 

 other words, the genealogy of Knobcone Pine indicates that it has 

 had an ancestry separate from that of its close relatives for sev- 

 eral million years. In contrast, the coastal closed-cone pines were 

 derived from a common ancestor that prevailed in the Pleistocene, 

 a period that began about one million years ago. (The Pleistocene 

 is sometimes called the "Ice Age" in allusion to the great glacia- 

 tions that occurred during that time.) All closed-cone pines are 

 connected to a common ancestor {P. masonii) in the Pliocene. 

 Finus masonii became extinct in the early Pleistocene, although 

 some of its traits persist in its modern descendants. The fossil 

 record also indicates that Monterey Pine was once considerably 

 more widespread in California than it is at present. Like some 

 other tree species in California, Monterey Pine has had its day, 

 evolutionarily speaking, and is on its road to natural extinction. 

 As a matter of fact, the only closed-cone pine which seems to be 

 holding its own in contemporary California is Knobcone Pine. 

 It is an interesting and somewhat puzzling contrast that both 

 Monterey Pine and Monterey Cypress — rare and remnant species 

 that are ecologically unsuccessful in their natural habitat — are 

 widely planted as windbreaks and timber trees in many areas of 

 the world, particularly in New Zealand and Australia, and that 

 in some of these southern regions these trees are invasive weeds 

 that have spread from areas in which they have been planted into 

 adjacent native plant communities. 



A particularly interesting local phase of the Closed-Cone Pine 

 Forest occurs in the Mendocino White Plains area of Mendocino 

 County in northern California. This phase is locally known as the 

 Pygmy Forest and occurs on the highly acid, sterile soils a few 

 miles inland from the immediate coast. The soil acidity and the 

 sterility are coupled with the fact that these soils are underlain 

 with an impervious hardpan and are waterlogged for much of the 

 winter rainy season. This combination of unfavorable ecological 

 characteristics results in the presence of an assemblage of dwarfed 

 trees, or natural bonsais, hence the name "Pygmy Forest" (Plate 

 6D). Trees of Pygmy Cypress (Cupressus pygmaea) and Bolander 

 Pine (Pinus contorta var. bolanderi) that occur on this soil may 



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