![]() glyptostroboides populations, the species diversity of the communities where this tree is found, and the ecological processes that influence them is important for conservation and management. Complex mosaics of stands of varying age, composition and structure intermingle with cultivated fields. However, in recent decades the extensive removal of native vegetation in these areas has left most of the remaining vegetation fragmented in patches across the landscape. sinicum, Tapiscia sinensis and Fagus longipetiolata (Chu and Cooper, 1950, Wu, 1980). The mountain areas of south-central China harbor flora distinguished by richness and a high degree of endemism and provide a refuge to many relicts from the Tertiary period, among them Nyssa sinensis, Cercidiphyllum japonicum var. Among the IUCN categories of threat, the species is listed as critically endangered (IUCN, 2006). The relict dawn redwood Metasequoia glyptostroboides Hu et Cheng (formerly Taxodiaceae, and now merged with Cupressaceae) currently survives only in wet lower slopes and montane river and stream valleys in the border region of Hubei and Hunan provinces and Chongqing municipality in south-central China (Cheng and Chu, 1949, Chu and Cooper, 1950, Wang et al., 2005, Leng et al., 2007). According to the fossil history, Metasequoia Miki was widely distributed in the Northern hemisphere throughout the Tertiary (Florin, 1963, Yu, 1995, Yang and Jin, 2000, LePage et al., 2005). Metasequoia is known as a living fossil, because it was found only in fossil records until 1946 (Miki, 1941, Hu, 1946, Hu, 1948, Merrill, 1948). These considerations are borne out in dealing with the topic at hand. The distribution of a species is determined mainly by its adaptability to the habitat and by barriers to dispersal, as well as by external events (Cox and Moor, 1993). ![]() Karron, 1991, Hamrick and Godt, 1996, Tamaki et al., 2008) have also demonstrated less immediate effects: endangered species whose populations are small and isolated are susceptible to loss of within-population genetic variation by genetic drift, leading to high extinction rates. Habitat degradation cannot only be the direct cause of local extinction of plant populations (e.g. Habitat changes alter the ecology of forest remnants in many ways, reducing the size of species populations and species richness, disrupting their recruitment dynamics and spatial structure. Human activities across the globe have transformed natural habitats into agricultural and artificial landscapes, bringing habitat loss, fragmentation and degradation, and in turn threatening the remaining plant populations. ![]() Our work detailing the plant populations in the habitats of this living fossil will be useful in establishing priorities for its recovery and conservation. Under present environmental conditions and land use, the dawn redwood will not maintain its natural range in south-central China. The detrimental activities of human residents include cultivation of profitable plants in the understory, selective cutting, harvesting of wood for fuel, and thoroughgoing collection of seeds for sale on the active market. The remaining specimens ranged from roughly 41 to some 265 years for an average near 95 years, with heights of 12–51 m averaging 27 m. glyptostroboides and have reduced species richness in direct response to human disturbance, as shown on several indices. In the last 41 years, habitat changes have effectively ended recruitment of M. Our study included all the known wild individuals of the species as well as analyses of the floristic diversity of their habitats. We investigated its population size and age structure, and provided a comparison to the study of Chu and Cooper (1950), documenting the changes of the past 60 years. The relict dawn redwood Metasequoia glyptostroboides Hu et Cheng is endemic to the region bordering Hubei and Hunan provinces and Chongqing municipality in south-central China.
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