By Sara Oldfield, Cambridge, UK
Restoration of degraded ecosystems is a global imperative recognised by international, regional and national environmental policies. Ecological restoration is required to address biodiversity loss, the related provision of ecosystem goods and services, and to contribute to tackling the impacts of climate change. Ensuring the provision of appropriate seed of a diverse range of species and of appropriate genetic provenance is a major requirement of ecological restoration and a major challenge. Botanic gardens manage at least one-third of the world's flowering plants in their living collections and seed banks, providing a very significant potential resource for ecological restoration.
Plant materials for ecological restoration are supplied from a variety of sources. Collection of seed from wild populations remains extremely important. Commercial growers, government agencies and NGOs all have important roles in native seed production. The scaled-up development of "Seed Production Areas" for wild seed, through partnerships, and with sound scientific and economic frameworks, is required as called for by Nevill et al (2016). Increased collaboration with botanic gardens is one approach to help meet the global demand for seed.
Globally there are over 3000 botanic gardens and related institutions. Initially established in Europe in the sixteenth century as centres of learning and cultivation of medicinal plants, botanic gardens have broadly extended their roles over the centuries. They now have a wide range of functions and associated expertise. Conservation of rare and threatened plants has been an extremely important role of botanic gardens since the 1970s. Collectively, since that time, botanic gardens have helped to raise the profile of plant conservation and influence global policy. The development of the Global Strategy for Plant Conservation (GSPC) of the Convention on Biological Diversity (CBD) was supported by botanic gardens from the outset, with ongoing coordination from Botanic Gardens Conservation International (BGCI).
One of the 16 targets of the GSPC (Target 8) calls for "At least 75% of threatened plant species in ex situ collections, preferably in the country of origin, and at least 20% available for recovery and restoration programmes". Progressing this target is providing a major boost in the supply of plant materials for ecological restoration. Currently, for example, 39 percent of 9,496 North American threatened taxa, 40 percent of 1,918 threatened European species and 37 percent of 4,404 threatened taxa of China are maintained in ex situ collections.
Seed banking is generally considered to be the most efficient and cost-effective means of ex situ conservation of threatened plant species. Seed banking allows for maximising the storage of genetic diversity and prevents the effects of "domestication" of species in living collections. Currently around 400 botanic gardens maintain seed banks. BGCI is promoting expansion of this activity through the Global Seed Conservation Challenge in order to help reach GSPC Target 8, enabling more material to be available for recovery and restoration programmes.
The progress of botanic garden in ex situ conservation of threatened plants is impressive. However, with the global shortage of appropriate plant materials for ecological restoration, botanic gardens may need to consider placing increased emphasis on common and ecologically important species required to meet restoration needs. Many of these species may already be in botanic garden cultivation. Botanic gardens in China for example cultivate 25,000 plant species, 90 percent of which are native. For each region, it remains important to identify and prioritize "foundation" or "workhorse" species that are needed at scale and to utilise the horticultural skills of botanic gardens to cultivate and propagate such plants for restoration projects (Fig. 1). Development and publication of propagation protocols is an important aspect of this work.
Figure 1. Forest Restoration at Kadoorie Farm and Botanic Garden (KFBG), Hong Kong, China, in 2014 (above) and 2017 (below, photo courtesy S. Blackmore).
In the US, the National Seed Strategy for Restoration and Rehabilitation is providing an important mechanism to engage botanic gardens in the production of plant materials for ecological restoration. The Strategy was launched in 2015 to ensure the availability of genetically appropriate seed to restore viable and productive plant communities and sustainable ecosystems. The Strategy engages 12 Federal agencies together with over 350 non-federal partners linked through the Plant Conservation Alliance (PCA). It builds on the national Seeds of Success (SOS) partnership program that has involved botanic gardens and other agencies in collecting native seed for long-term storage and use in restoration since the turn of the century.
Chicago Botanic Garden (CBG), a lead organisation in the development and implementation of the National Seed Strategy and current Chair of the PCA Non-Federal Committee, is one of the key US botanic gardens involved in supporting the Strategy. CBG is a member of the SOS Partnership, hosting coordination on behalf of the USDI Bureau of Land Management, and runs the Conservation and Land Management Internship Program (CLM). This scheme trains over 100 young scientists in seed collection each year in support of delivery of SOS. Chicago Botanic Garden also conducts research to inform native plant materials development and restoration, with most of this work carried out on the Colorado Plateau. Monitoring of long-term study plots in Utah and Colorado supports the identification and development of restoration species and quantifies how species and seed-source selection impacts ecosystem function in restored habitats. Research trials are also underway at the Garden using SOS collections and additional seed collections.
Amongst the other botanic gardens involved in implementation of National Seed Strategy are the New England Wildflower Society and North Carolina Botanical Garden, both partners in the national SOS program and currently collecting seed for restoration of coastal areas that were damaged by Hurricane Sandy. The New England Wildflower Society is responsible for collecting seed in Maine, New Hampshire, Massachusetts, Rhode Island, and Connecticut. The North Carolina Botanical Garden is responsible for seed collecting in Maryland and Virginia to support restoration efforts. Nearly 200 workhorse species have been collected by the two gardens and training is provided to expand high quality seed collection.
The US National Seed Strategy provides a model for other countries to follow. A key component is its partnership approach involving federal agencies and the private sector. Globally, the GSPC provides a very broad framework for partnership, within which native seed issues are indirectly addressed. Botanic gardens are also working in partnership through the Ecological Restoration Alliance of Botanic Gardens (ERABG) established in 2012 and facilitated by BGCI. This Alliance aims to mobilize botanic gardens, arboreta and seed banks to carry out science-based ecological restoration. Demonstration projects are highlighted. As noted by Hardwick et al, 2011, botanic gardens are well-placed to take an increasing part in ecological conservation because they:
Emphasize science-based approaches
Maintain well-documented living plant, seed and voucher collections
Generate knowledge of the genetic, physiological, horticultural and ecological characteristics of plants (and their seeds)
Act as stewards of rare and threatened species
Provide expertise for teaching, training and outreach
Collaborate through national, regional and global networks
Botanic gardens maintain a very wide range of documented plant species and skills as noted above. They manage ecological restoration projects on a variety of scales and provide plant materials for restoration projects managed by others. With nearly two-thirds of the world’s ecosystems degraded to some degree, the restoration of resilient, well-connected ecosystems needs strong partnerships including all relevant stakeholders. The work of botanic gardens in storage, production and provision of native seed of both threatened and common species should be highlighted and botanic gardens encouraged to act as local hubs for ecological restoration.
More information on the work of botanic gardens in conservation and ecological restoration can be found in the recently published book: Blackmore, S., and Oldfield, S.F. (Editors). 2017. Plant Conservation Science and Practice. The Role of Botanic Gardens. Cambridge University Press.
References:
Hardwick, K.A., Fiedler, P., Lee, L.C., Pavlik, B., Hobbs, R. et al. (2011). The role of botanic gardens in the science and practice of ecological restoration. Conservation Biology 25: 265-275.
Nevill, P.G., Tomlinson, S., Elliott, C.P., Espeland, E.K., Dixon, K.W. and Merritt, D.J. 2016. Seed production areas for the global restoration challenge. Ecology and Evolution 6:7490-7497.