Thursday, August 9, 2007: 3:40 PM
Willow Glen II, San Jose Marriott
Ultramafic soils and vegetation in California are widely distributed covering several types of habitats such as mountain slopes, barrens, vernal pools, stream banks, etc. from sea level to high in the mountains.
The main recognized vegetation-types include the natural potential vegetation (climactical vegetation) of these areas: conifer forests, conifer woodlands, and sclerophyllous chaparrals.
In over 10 years of geobotanical research in these territories throughout California state more than 500 phytosociological relevés were collected following the last approaches on Braun-Blanquet vegetational methods.
Our results recognize five chaparral associations with a precise climatic and biogeographical value, peculiar floristic composition (including rare or sensitive species as characteristic species), and dynamic patterns; all of them are framed in the phytosociological alliance Quercion duratae Sánchez-Mata, Barbour and Rodríguez-Rojo [in Rivas-Martínez] 1997. All these chaparral-types can be considered as rare and threatened vegetation-types by its own peculiar features. The preliminary phytosociological names and territorial ranges for the recognized associations are newly proposed as follows:
-Ceanotho jepsonii-Quercetum duratae: North Coast Ranges, Great Valley
-Arctostaphylo glaucae-Quercetum duratae: Central Coast Ranges
-Ceanotho albiflori-Quercetum duratae: Bay Area
-Arctostaphylo viscidae-Quercetum duratae: Sierra Nevada
-Yucco whipplei-Quercetum duratae: South Coast Ranges
The character of these peculiar habitats concerning the ultramafic endemism is a well-known feature of the California flora, and ultramafic rocks and soils contribute the most rare taxa to the standard rarity lists as show the current California Native Plant Society (CNPS) list where the inusual chemical characteristics of the ultramafic habitats promote the rarity condition for almost 300 taxa. Some interesting endemic plants from the California ultramafic chaparrals listed under Federal Law are Arctostaphylos hookeri subsp. ravenii, Arabis macdonaldiana, Calochortus tiburonensis, Ceanothus ferrisae, Cirsium fontinale s.l., etc.
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The main recognized vegetation-types include the natural potential vegetation (climactical vegetation) of these areas: conifer forests, conifer woodlands, and sclerophyllous chaparrals.
In over 10 years of geobotanical research in these territories throughout California state more than 500 phytosociological relevés were collected following the last approaches on Braun-Blanquet vegetational methods.
Our results recognize five chaparral associations with a precise climatic and biogeographical value, peculiar floristic composition (including rare or sensitive species as characteristic species), and dynamic patterns; all of them are framed in the phytosociological alliance Quercion duratae Sánchez-Mata, Barbour and Rodríguez-Rojo [in Rivas-Martínez] 1997. All these chaparral-types can be considered as rare and threatened vegetation-types by its own peculiar features. The preliminary phytosociological names and territorial ranges for the recognized associations are newly proposed as follows:
-Ceanotho jepsonii-Quercetum duratae: North Coast Ranges, Great Valley
-Arctostaphylo glaucae-Quercetum duratae: Central Coast Ranges
-Ceanotho albiflori-Quercetum duratae: Bay Area
-Arctostaphylo viscidae-Quercetum duratae: Sierra Nevada
-Yucco whipplei-Quercetum duratae: South Coast Ranges
The character of these peculiar habitats concerning the ultramafic endemism is a well-known feature of the California flora, and ultramafic rocks and soils contribute the most rare taxa to the standard rarity lists as show the current California Native Plant Society (CNPS) list where the inusual chemical characteristics of the ultramafic habitats promote the rarity condition for almost 300 taxa. Some interesting endemic plants from the California ultramafic chaparrals listed under Federal Law are Arctostaphylos hookeri subsp. ravenii, Arabis macdonaldiana, Calochortus tiburonensis, Ceanothus ferrisae, Cirsium fontinale s.l., etc.
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