The Edible Plant Dichelostemma capitatum: Its Vegetative Reproduction Response to Different Indigenous Harvesting Regimes in California

To more thoroughly understand the ecological effects of harvesting geophytes for food by American Indians, an investigation of the ethnobotany and population dynamics of Dichelostemma capitatum (blue dicks), an attractive source of nutrition to many California Indian groups was undertaken. Some cultural groups harvest the corms and replant the cormlets, spare plants, and harvest after seeding to ensure replenishment of seed. Some Indian elders equate judicious harvesting with the maintenance and enhancement of field populations of this geophyte. A field experiment was conducted to determine the degree to which differences in intensity and timing of harvest, with and without replanting of cormlets, have any effect on corm and cormlet production. We found that harvesting at 100% intensity, through digging up all plants and corms, and without replanting cormlets at the seed stage, significantly reduces numbers of corms and cormlets compared to the controls (no harvest). However, harvesting at 50% intensity, through digging up half of all plants and corms at the flowering or seed stages, without replanting cormlets, was not significantly different from the controls (no harvest). The results suggest that harvesting blue dicks corms with a digging stick in the latter way could yield a sustainable level of harvest. Indigenous harvesting and management regimes may offer some of the best examples of long-term uses and management of the regional flora without detriment to its biodiversity. Restorationists are urged to study and experimentally mimic indigenous disturbance regimes and their ecological effects known to occur historically in various ecosystems. In some cases, areas will greatly benefit from the reintroduction of management and harvesting regimes that authentically simulate ancient indigenous interactions.