Wilken, Dieter , McEachern, Kathryn , Christian, Julie .
Recovery of the federally endangered Santa Cruz Island bush mallow, (Malacothamnus fasciculatus var. nesioticus).
In 1995 we began studies of Santa Cruz Island bush mallow to determine its reproductive biology, ecological requirements, and distribution. After 100+ years of depredation by sheep, which were removed by 1985, two populations of fewer than 20 plants each survived. Molecular studies showed that each population was composed of 1-3 genets. During the course of the study, two additional populations of similar size were discovered. Ex situ studies showed that plants were self-compatible, developed extensive rhizomes after one year of growth, and were readily propagated from cuttings. We found no evidence of inbreeding depression, estimated from seed set, viable embryos, and germination rates. Ad hoc ex situ observations and initial in situ planting efforts suggested that supplemental water was critical to survival, even during an average winter rainfall. We developed an experimental recovery plan composed of 4 plots located at varying elevations and aspects. Each plot was enclosed to exclude feral pigs, which posed a continuing threat. Each plot was planted with twelve 6-month old rooted plants derived from each of 3 different natural populations. Plants were provided supplemental watering for 3 months. Survivorship after one year ranged from 46% to 91%. Significant differences in survivorship over all plots were observed relative to provenance of plants. After 12 months some plants were flowering and reproducing vegetatively.
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1 - Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, California, 93105-2199, USA
2 - USGS, Western Ecological Research Center, Channel Islands Field Station, 1901 Spinnaker Drive, Ventura, CA, 93001
3 - University of Wisconsin, Dept. of Botany, Birge Hall, Madison, WI, 53706
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 1:30 PM