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THE ROLES OF SOIL TYPE AND SHADE INTOLERANCE IN LIMITING THE DISTRIBUTION OF THE EDAPHIC ENDEMIC CHORIZANTHE PUNGENS VAR. HARTWEGIANA (POLYGONACEAE)
Jodi M. McGraw and Anna L. Levin
Vol. 45, No. 2 (APRIL-JUNE 1998), pp. 119-127
Published by: California Botanical Society
Stable URL: http://www.jstor.org/stable/41425251
Page Count: 9
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Understanding the ecological factors that cause narrow geographic range and habitat specificity is essential for the conservation of rare species of edaphic endemic plants. Here we investigated the relative roles of soil and light in limiting the distribution of Chorizanthe pungens Benth. var. hartwegiana Rev. & Hardham (Polygonaceae), an annual plant endemic to open patches of low nutrient soils in the sandhills habitat of the Santa Cruz Mountains, Central Coastal California. Seedlings were grown in a controlled pot experiment under three light conditions and five soil treatments. The growth, survival, and reproduction of individual plants were compared. Plants were least successful when grown on their native low nutrient soil, suggesting that soil type is not a limiting factor in the taxon's distribution. However, when grown under high shade, survivorship, growth, and reproduction of individuals were low. This suggests that shade intolerance is the major cause of this taxon's restriction to open, sandy areas. Thus management to preserve this federally endangered species should include artificial or natural disturbances to prevent populations from being extirpated due to encroachment of taller, shade-producing species.
Madroño © 1998 California Botanical Society