Preservation And Conservation Of Some Endangered Species In Urban Green Spaces

The in situ conservation of some species now faces the problems of global climate change and human disturbance such as forest restoration. At the same time, the space of ex situ conservation (such as botanic garden) is also limited. Therefore, it is demanded urgently to find more complementary areas to protect species. Urban green spaces have received more and more attention for conservation of the rare and endangered species. However, the conservation potential in urban green spaces has been less studied. In this paper, the native endangered plants in the Yangtze River Delta region in China are the object of study, including Changium smyrnioides, Isoetes sinensis, Calycanthus chinensis, Heptacodium miconioides, Cinnamomum japonicum, Neolitsea sericea. We set up a comprehensive research framework including data collection, field investigation, eco-physiological and morphological experiment, urban green spaces investigation and remote sensing analysis for introduction of plants into urban green spaces. Firstly, based on limiting factors, we carried out field investigation, eco-physiological and morphological experiment to determine the habitat requirements of target species (C. smyrnioides and C. chinensis). And then, in urban green spaces, we found out the suitable habitats similar to that of the wild and also evaluated the introduction potential of the target species. Simultaneously, through the research of historical and current distribution of each species, we analyzed the cities which can introduce these endangered plants and located the suitable habitat types in urban green spaces to promote the protection and preservation of endangered plants. The results as follows:(1) The endangered species C. smyrnioides mainly occurs under the deciduous trees with no leaves from November to next April. When March to April, the understory light and temperature conditions were suitable for the growth of C. smyrnioides. In urban green spaces of Hangzhou and Ningbo City, the deciduous tree species accounted for 62% and 60% of the total number of tree species, respectively. The spaces under these deciduous trees have potential for C. smyrnioides cultivation. Moreover, the understory habitats of the important deciduous species with long no-leaf period are most suitable for C. smyrnioides introduction. At present, there are 18.97 km2 and 18.42 km2 of potential habitats to introduce C. smyrnioides in urban green spaces of Hangzhou and Ningbo City, If the potential habitats are taken full advantage,1.01×108 and 9.8×107 individuals of C. smyrnioides can be cultivated, respectively.(2) The eco-physiological performance of C. chinensis showed the species can distribute from margin habitat to understory habitat of the forest with weak light. Although C. chinensis had advantage under the low light condition because of greater leaf area and SLA, the leaves were so easy to be damaged by wind. Therefore the forest margin habitat was not optimal. The niche of C. chinensis was crown density of 0.45-0.99 under the limit of wind and light. The understory of the forest with this crown density was the most suitable habitat for C. chinensis. At present, there are 47% of urban green spaces in park of Hangzhou City meeting the need of C. chinensis. There are 29.64 km2 of potential habitats for introduction of C. chinensis, and 9.5×106 individuals of C. chinensis can be cultivated. The suitable habitats can be created and maintained by artificial management.(3) In the Yangtze River Delta region, the cities which have great introduction potential of all of six endangered species include Nanjing, Changzhou, Suzhou, Hangzhou, Ningbo, Wenzhou, Huzhou, Shaoxing, Jinhua, Hefei, Wuhu, Tongling, Anqing, Huangshan, Lu’an, Xuancheng and Chizhou. The types in urban green spaces are mainly open field, forest margin, sparse forest, thick forest, shoreside and roadside. The open field, forest margin and shoreside are suitable to introduce the heliophile including C. japonicum and N. sericea, where H.miconioides, C. smyrnioides and C. chinensis can also survive. The shoreside is suitable for the hygrophyte including I. sinensis and H.miconioides. The thick forest and the tree base in sparse forest are suitable for shade tolerant and shade plants including C. smyrnioides. The region in sparse forest covered by the canopy is suitable for shade tolerant plants with weak wind resistance, including C. chinensis, and for plants with strong wind resistance including H. miconioides and C. japonicum. With thin soil and frequent human interference, shoreside and roadside are suitable for plants with strong ability to withstand disturbance including H. miconioides, C. japonicum and N. sericea.(4) In the study of habitats in city, with the help of Google Earth (GE), estimation of crown density, localization of deciduous tree and observation of green spaces types are efficient and economical. In the wild, due to the constraints of time and manpower, the points selected randomly for test are very limited. However, the limit on GE is little so that the work can be completed quickly relatively with large area sampled. Moreover, the estimation experiment on GE has good repeatability. At present, GE provides high resolution images for most cities, so the experiment is not limited to these cities in the study and the study area is easy to expand.