Conservation ecology of rare plants within complex local habitat networks

Effective conservation of rare plant species requires a detailed understanding of their unique distributions and habitat requirements to identify conservation targets. Research suggests that local conservation efforts may be one of the best means for accomplishing this task. We conducted a geographical analysis of the local distributions of rare plants in Napa County, California, to identify spatial relationships with individual habitat types. We measured the potential contribution of individual habitats to rare plant conservation by integrating analyses on overall diversity, species per area, specificity-weighted richness, presence of hotspots, and the composition of the rare plant community in each habitat type. This combination of analyses allowed us to determine which habitats are most significant for rare plant conservation at a local scale. Our analyses indicated that several habitat types were consistently associated with rare plant species. In broad terms, grasslands, oak forests, coniferous forests, wetlands, serpentines, chaparral, and rock outcrops were most consistently highlighted. No single habitat stood out in every analysis however, and therefore we conclude that careful selection of an assemblage of habitats that best represents diverse, restricted and unique rare plant communities will be the most efficient approach to protecting rare plant habitat at local scales. Accordingly we present a means of identifying conservation targets and protecting global biodiversity through local efforts.

A History of Hawaiian Plant Propagation

The National Tropical Botanical Garden (NTBG) has been a leader in the propagation and cultivation of rare native Hawaiian plants for several decades. The organisation’s work in rare plant conservation started primarily with field research and has evolved into a large-scale nursery operation. The NTBG now produces thousands of plants a year for ex situ conservation, garden collections and restoration projects. Here a number of Hawaiian species are reviewed, and appropriate propagation and cultural methods for each are discussed.

Horticultural Science and Rare Plant Conservation

Horticultural science has an essential role to play in the conservation of rare plants, but to date, most horticultural research in this field has taken place on an informal rather than experimental basis. Plant conservation as a scientific and practical discipline would benefit greatly from applying the more rigorous approach characteristic of commodity-oriented horticultural research. In turn, the profession of horticultural science has a great deal to gain by participating more actively in plant conservation programs. Benefits include an influx of new ideas, new people, and new resources. Some of the traditional research fields within horticulture that are directly relevant to rare plant conservation include: seed technology, propagation and tissue culture, nutrition, growth regulation, soil management, and protection from pests and diseases. Three case studies illustrate various ways in which the theory, technology, and knowledge base of horticulture can be applied to plant conservation. They include the rare plant propagation program at Bok Tower Gardens, Lake Wales, Fla.; mountain meadow revegetation projects in Mount Rainier and Olympic National Parks in Washington; and research activities of the recently established Georgia Plant Conservation Alliance.