Rare plants in the Golden Gate Estuary (California): the relationship between scale and understanding

Abstract

We analysed 10 rare-plant projects conducted from 1982 to 2005 for trends in scientific findings, project costs, effort and efficacy. Our purpose was to determine whether generalisations about these factors can be found, and if so, whether they might be useful for designing and implementing successful future rare-plant endeavours. Analysis results revealed that rare plant species persist despite their restriction to a highly fragmented and degraded urbanised estuary of more than seven million people. Also important were the findings that with sufficient funding, successful rare-plant reintroduction is possible in the short-term at minimum. Habitat considerations, however, are paramount—i.e. habitat requirements of a rare species should be known before reintroduction for the restoration effort to be likely to be successful. Understanding ecosystem functions that support rare species, therefore, remains the highest priority for rare-plant restorationists. Project costs varied significantly, as expected, but a ‘middle ground’ provides necessary and sufficient funding to conduct most rare-plant work for one or a few species. Costs rise, but not linearly, when additional rare taxa are included. Given our experience is applicable elsewhere, taking an ecosystem approach to protection of rare flora is most successful and cost effective.