Wild Plant Species with Extremely Small Populations Require Conservation and Reintroduction in China

For reintroduction of rare and endangered plants, plants protected and propagated via ex situ conservation are returned to their original natural and semi-natural ecosystems or to suitable wild habitats. The goal is to establish a population with sufficient numbers and genetic resources to enable it to adapt to change and to be self-sustaining and self-renewing (Griffith et al. 1989; IUCN 1998). International organizations have also published guidelines for the reintroduction of wild species, and at least 249 reintroduction trials involving 172 taxa have been conducted worldwide (Godefroid et al. 2011). More than 890 papers related to reintroduction have been published (Polak and Saltz 2011). To date, there have been 62 successful reintroduction cases in the world (Albrecht et al. 2011). Based on ex situ conservation and research on threatened plants, China has performed several reintroduction experiments. Until now, 38 plant species have been successfully reintroduced. Reintroduced herbs include Primulina tabacum, Paphiopedilum wardii, Paphiopedilum armeniacum, Paraisometrum mileense, Tigridiopalma magnifica, Metabriggsia ovalifolia, Paphiopedilum malipoense, and Doritis pulcherrima. Reintroduced shrubs include Myricaria laxiflora (Chen et al. 2005), Loropetalum subcordatum, and Cycas debaoensis (Ren et al. 2008). Reintroduced trees include Disanthus cercidifolius subdp longipes, Nageia nagi, Manglietia longipedunculata, Bretschneidara sinensis, Parakmeria lotungensis, Davidia involucrate, Dipteronia sinensis, Lirianthe odoratissima, Manglietia aromatica, Euryodendron excelsum, Formanodendron doichangensis, Pachylarnax sinica, Cyclobalanopsis sichourensis, Nyssa yunnanensis, and Diploknema yunnanensis (Sun et al. 2006; Zheng and Sun 2009). The lower plant Adiantum reniforme. var. sinense has also been successfully reintroduced (Ren 2012). The reintroduction of plant species with extremely small populations in China involves a number of main features and problems. Botanical gardens play an important role in the early stage of wild plant reintroduction because such gardens research introduction techniques are related to ex situ conservation. The government is important because it promotes interactions with international organizations and it develops and implements the relevant laws and regulations. For example, the State Forestry Administration approved the “Implementation Plan for Saving Wild Plants of Extremely Small Populations” in 2012; Botanical Garden Conservation International launched a “10 species program” in China aiming at insuring species survival and population recovery. Those works are conducted mainly in relatively developed areas, such as Guangdong and Zhejiang provinces, or biodiversity-rich regions (such as Yunnan province), and over a short period of time, but few related papers have been published. The plant species that have been systematically studied include Primulina tabacum, Tigridiopalma magnifica, Bretschneidara sinensis, Pachylarnax sinica, and Cyclobalanopsis sichourensis. The species that have been reintroduced are confined to those in single-species families and genera, and relic species or rare and endangered species. With respect to the reintroduction of wild plants, researchers in China have studied the ecological characteristics, population genetics, and breeding biology of 28 species. The research has confirmed that these species have narrow distribution areas and shrinking population sizes related to anthropogenic disturbance and climate change. Primulina tabacum, Tigridiopalma magnifica, and Cycas changjiangensis have had 3, 1, and 2 wild distribution points (populations), respectively, that became extinct in the past decade (Ren et al. 2010, 2012). The genetic diversity of these plants is generally low. These plants have varying degrees of natural reproduction barriers (Jian et al. 2010). To increase the successful reintroduction of rare and endangered species, researchers have combined methods of biotechnology and ecological restoration. Our investigations showed that reintroduction of Primulina tabacum often required the use of bryophytes as nurse plants (Ren et al. 2010). Successful reintroduction of Tigridiopalma magnifica indicated that rare and endangered species can be transplanted and established with anthropogenic assistance under the conditions of global climate change, which clarified current academic debate (Ren et al. 2012). We have also successfully reintroduced some trees (including species of Magnoliaceae) and produced substantial numbers of plants from seeds. Some of these seedlings have been used for urban landscaping. Most importantly, we have established the following protocol for the reintroduction of rare and endangered plants: first, select the appropriate target plant species; second, conduct basic research on their breeding and other aspects of their biology and ecology; and then, reintroduce them to the wild while also developing their market-oriented production. By consulting with regional and national agencies concerned with ecological planning, we have promoted this protocol for the reintroduction of rare and endangered plants throughout China.