- Farming for Restoration: Building Bridges for Native Seeds
In both Europe and the United States, a shortage of native plant material frequently precludes successful restoration. Native plant materials are needed to restore ecosystem functioning and services, provide for in situ conservation of biodiversity (e.g., Hobbs and Cramer 2008), maintain genetic diversity (Bischoff et al. 2010), and afford resistance to invasive species. Long-term stewardship goals are to create diverse, resilient systems with the genetic diversity and structure to facilitate adaptation to climate change and other environmental perturbations (e.g., Johnson et al. 2010). Commercial seed mixtures of non-native species and genetically uniform varieties threaten local diversity. Consequently, efforts to develop native seed sources are receiving considerable attention.
During the 7th Society for Ecological Restoration European Conference in Avignon, a special session focused on the successes and challenges of producing and using native plant material on a regional scale. European and American participants highlighted common issues encountered in developing native seed supplies (Figure 1), creating new market niches, and adapting seed certification procedures for use with native materials with the goal of sharing effective solutions and devising new approaches. Here we share the key findings and next steps outlined in this special session.
Several biological and technical challenges hinder the development of native plant programs at local or regional scales, such as: 1) identifying species-specific seed zones derived from ecological studies and provisional seed zones based on climatic and environmental variables (Johnson et al. 2010); 2) developing genetically diverse, ecologically adapted materials (Johnson et al. 2010); 3) formulating strategies to track plant materials from wildland harvest through agricultural production as well as to manage stock seed or other types of plant materials (Figure 2); 4) developing seed technology for diverse woody and herbaceous species; 5) understanding pollinator requirements and potentially managing wild pollinators in seed fields; 6) identifying cultural practices, including pest and disease control, for maximizing seed production; and 7) developing effective strategies and equipment for reestablishing native plant communities (USDI BLM 2009). Major political and economic obstacles include sustaining funding for research and development, creating new market niches for seed growers, and creating and maintaining collaboration among researchers, seed regulatory agencies, the private seed industry, and private and public end users.
One of the main topics in the session was the limited European production of native plant material owing to high costs and lack of propagation experience. Native seed production is often organized by local nongovernmental organizations (NGOs) or very small companies, and seed quantities and range of species are limited. Moreover, the lack of administrative support for native plant material leads to widespread use of low-cost commercial seed mixtures containing horticultural and agricultural cultivars and wildflower seeds of unknown or nonlocal origin. Use of easily propagated and widespread cultivars ensures the continuous availability and affordability of these mixtures but ignores the importance of local genotypes. Conrad (2007) and Tischew and others (2010) evaluated grassland restorations to counteract impacts of infrastructural projects on natural systems in Germany. Approximately [End Page 219] 70% of the projects used standardized commercial seed mixtures. However, using these mixtures did not help to reach the species-richness objective. Deficits in grassland restoration projects owing to the use of non-native seed mixtures have been well documented (Kiehl et al. 2010).
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In the future, restoration, as well as revegetation of grasslands outside cities or agricultural areas, should be accomplished only with seeds of local origin produced regionally or harvested from local species-rich near-natural grasslands. To facilitate this objective, legal support must be secured. The German Law for Nature Conservation demands that only species of local provenance will be used after 2020 in restoration and revegetation projects, thus confining the use of nonlocal ecotypes and cultivars to cities, agriculture, and forestry.
In recent years, the European Union (EU) has supported several major projects to expand propagation and use of...