One of the outgrowths of the Convention on Biological Diversity (CBD) discussed in the last post was the Global Strategy for Plant Conservation (GSPC) of 2002. Updated 10 years ago, it has five objectives and within them 16 goals or targets. While not all the targets have been met, there has been a great deal of work done toward them, and herbaria have been at the forefront of these efforts as have botanic gardens. In fact, Botanic Gardens Conservation International, a global partnership, has taken a lead. The first objective, not surprisingly was to understand plant diversity and one of the targets was an online flora of all known plants; this effort is headed by the Royal Botanic Gardens, Kew. Though not complete, the flora does include information on each listed species’ range, with related literature and a sampling of illustrations and herbarium specimens.
Another target was to determine, “as far as possible,” the conservation status of all known plants. This goal is much more difficult to achieve, but the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species established in 1964 is the most comprehensive inventory of species vulnerability worldwide. Those with economic or cultural value, and those most apparent to humans, are more likely to be included because a great deal of work goes into getting a species listed, and delisted if its status improves. In the case of plants, evaluation includes research in herbarium collections to determine a plant’s range in the past compared to what it is now, and at times to clarify precisely what species is being listed. To put teeth into the protection of species on the Red List, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was presented at a Washington, DC meeting in 1973. It controls commerce in endangered species and comes into play in botany especially with illicit trade in timber from rare trees and exotic plants such as orchids and cacti.
About a third of the world’s plants are threatened with extinction. Such loss could be comparable to some earlier mass extinctions including the one about 65 million years ago that brought the age of dinosaurs to an end. But it was not just dinosaurs that disappeared, that’s not the way the living world works. Species are so interdependent that a single extinction can result in greater loss: the species’ parasites and predators could also suffer population crashes leading to extinction. That’s why conservationists focus on protecting habitats and ecosystems, not individual species such as a beautiful orchid or bird. Species that catch the human eye are linked to many others such as microscopic invertebrates and fungi that are less obvious but equally important.
The goals of the second GSPC objective are more multispecies in scope including conserving 15% of each ecological region or vegetation type and 75% of the most diverse areas, the biodiversity hotspots. Other goals include growing 75% of threatened plant species in situ, that is, in their natural habitat and also ex situ in botanical gardens or other protected areas, preferably in the plant’s home country. This last goal highlights the importance of botanic gardens in biodiversity conservation. They have become safe havens for many species, places where plants can be cultivated and propagated. In a sense, this is an outgrowth of the mission of nineteenth-century colonial botanic gardens and their mother gardens in Europe, such as Kew in London and the Jardin des Plantes in Paris. Now there are more gardens in plants’ home countries and under the supervision of the countries’ own people, who, thanks to the CBD, can make binding decisions about how these plants will be distributed and used, including for ecosystem restoration projects. However, the resources of gardens in developed countries are still necessary; they nurture plants on site, also sending them back to the country of origin, with the goal of having 20% of the plants available for restoration work.
In addition, botanical gardens preserve specimens to document what is grown and some saving small samples of plant material under ultra-cold conditions for future use in DNA sequencing studies. Ideally, each sample is associated with a herbarium specimen voucher for reference. Just as herbaria were important to economic botany in the nineteenth century, they are crucial to biodiversity research in the twenty-first. The number of herbaria in developing nations has increased substantially in this century and the number of specimens housed is rising at an even faster pace, in part with the impetus of the GSPC. The best resource for tracking herbaria and their growth is the annual report of the online Index Herbariorum, the definitive guide to the location and holdings of the world’s herbaria.
The GSPC’s third objective is for plant diversity to be used in a sustainable and equitable manner. This depends on support from herbaria and from the international community in the form of the CITES treaty to prevent trade in endangered species. Because of economic deprivation in many developing countries, there is great pressure to profit from natural resources, including plants and animals. Uprooting rare plants does more than just reduce the population, it damages the entire habitat and makes it less likely that the plants can grow back. Herbaria play a role in, for example, providing evidence in court cases arising from the seizure of endangered plants. Taxonomists may be called on to verify that the species is in fact on the Red List. The same is true of illegal trade in timber from endangered tree species, with xylarium collections’ wood samples compared to recovered timber. CITES does have a downside as far as herbaria are concerned in terms of shipping specimens internationally. There are forms that have to be filled out to certify that the material is only for research purposes and not for profit. At times the red tape can be excessive, making the work of herbarium managers frustrating.