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Tang C.Q.,Yunnan University | Yang Y.,Chongqing University | Ohsawa M.,Yunnan University | Momohara A.,Chiba University | And 5 more authors.
PLoS ONE | Year: 2015

A rare coniferous Tertiary relict tree species, Thuja sutchuenensis Franch, has survived in the Daba Mountains of southwestern China. It was almost eliminated by logging during the past century. We measured size and age structures and interpreted regeneration dynamics of stands of the species in a variety of topographic contexts and community associations. Forest communities containing T. sutchuenensis were of three types: (1) the Thuja community dominated by T. sutchuenensis, growing on cliffs; (2) the Thuja-Quercus-Cyclobalanopsis community dominated by T. sutchuenensis, Quercus engleriana and Cyclobalanopsis oxyodon, along with Fagus engleriana and Carpinus fargesiana, on steep slopes; (3) the Thuja-Tsuga-Quercus community dominated by T. sutchuenensis, Tsuga chinensis, and Quercus spinosa, on crest ridges. The established seedlings/saplings were found in limestone crevices, on scarred cliff-faces, cliff-edges, fallen logs, canopy gaps and forest margins. The radial growth rate was 0.5-1.1 mm per year. Its growth forms were distorted. It had strong sprouting ability after disturbances. The T. sutchuenensis population thrives on cliffs where there is little competition from other species because of harsh conditions and rockslide disturbances. It is shade-intolerant but stress-tolerant. Its regeneration has depended on natural disturbances. © 2015 Tang et al.

Tang C.Q.,Yunnan University | Yang Y.,Chongqing University | Yang Y.,Chongqing Wulingshan Mountain Forest Ecosystem Research Station | Ohsawa M.,Yunnan University | And 3 more authors.
American Journal of Botany | Year: 2013

Premise of the study: We investigate factors supporting the persistence in southern China of a rare Tertiary relict tree species, Liriodendron chinense, which has been almost eliminated by recent land use conversion. We hypothesize that cultural practices and traditional sustainable forest resource uses provide niches for the species' regeneration that will complement infrequent natural disturbances, while the species' survival on remote mountain slopes where there are no humans depends on natural disturbances alone. Methods: We examined and analyzed various landscape contexts, community associations, age distributions, and regeneration patterns of Liriodendron chinense. Key results: Forest communities containing Liriodendron chinense were of three types: (1) village fengshui forests-mature forests dominated by Tertiary relict taxa Liriodendron, Toona, and Emmenopterys, protected for their supposed spiritual value; (2) young secondary forests near villages, dominated solely by Liriodendron; and (3) old secondary forest remnants on mountain slopes far from villages, dominated by Liriodendron with other Tertiary relicts of the genera Davidia and Sassafras. The age structure of Liriodendron indicated ample recruitment in the fi rst two forest types, where the activities of local people have provided regeneration niches for the survival of this shade-intolerant pioneer species. On the remote mountain slopes that have never been converted to agriculture, Liriodendron has survived through regeneration made possible by natural disturbances. Conclusions: The traditional human land use, infl uenced by cultural values, has supplemented infrequent natural disturbances, providing regeneration niches for this and other Tertiary remnant species near villages in mountain valleys, while on uninhabited mountain slopes the species depends on natural disturbances to survive. © 2013 Botanical Society of America.

Qian S.,Chongqing University | Yang Y.,Chongqing University | Tang C.Q.,Yunnan University | Momohara A.,Chiba University | And 2 more authors.
Forest Ecology and Management | Year: 2016

Owing to the existence of global Pleistocene refugia, the relict and ancient component of the modern endemic flora is considerable in South-Central China. Study of these relict species helps to understand past and recent ecological processes affecting species persistence, and also provides knowledge to guide human-assisted management and conservation practice. In this study, we investigated the current status of the remnant populations of Cathaya argyrophylla, one of the emblematic "living fossils", growing in the Dalou Mountains of South-Central China. We quantified the population structure of C. argyrophylla and investigated demographic changes of seedlings over a ten year period to learn the plant's regeneration patterns following the establishment of two national and provincial nature reserves in late 1970s. Notable "gaps" in age structure over 40 years were found, suggesting significant recruitment failures in these scattered population since the establishment of the nature reserves. Further, the number of dead individuals peaked at ages between 40 and 80 years and the seedlings showed high mortality in the past 10 years, probably due to intensified competition from the nearby broad-leaved trees and the reduction of suitable micro-habitats. These facts indicated that attention needs to be paid and follow-up measures should be taken to more effectively conserve C. argyrophylla in the future. © 2015 Elsevier B.V..

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