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Background Schima genus of Theaceae is confined to subtropics and tropics of South, East and Southeast Asia. Thirteen species of Schima are distributed in subtropical China. Many of them appear as dominant canopy species in the subtropical forests. To date, Schima species richness distribution patterns of China have remained unknown. Meanwhile, there has been a longtime debate as to whether forests dominated by Schima species are early or late successional forests. We aim to clarify Schima species richness patterns and these species’ roles in the forest succession and regeneration dynamics of the subtropical ecosystem in Yunnan Province, China. Method We mapped Schima species richness distribution patterns in China. Based on 71 vegetation plots, we analyzed forest characteristics, population structure, and regeneration dynamics of Schima species in Yunnan. Results Yunnan was found to harbor the greatest richness and the highest rarity-weighted richness of Schima species in the subtropical regions of China. We classified five primary and six secondary forest types containing Schima species as one of dominants. Yunnan had the high floristic diversity and varying stand structure of forests containing Schima species. The Schima species studied generally had a sporadic regeneration type and a long life-span. Four species (Schima argentea, Schima villosa, Schima sinensis, Schima sericans) were shade-intolerant. But three species (Schima noronhae, Schima khasiana and Schima wallichii) were considered as bi-modal type species having shade-intolerant and shade-tolerant traits. Schima noronhae was seen to be a top dominant in late successional forests, while S. wallichii was found as a top-dominant in early or middle or late successional forests. S. khasiana, Schima villosa, Schima sinensis usually appeared as a top dominant in early or middle successional secondary forests, though they also presented as a second dominant in late-successional forests. Schima argentea and Schima sericans dominated only in the early or middle/seral successional forests. Schima species’ regeneration establishment depended mainly on forest canopy gap formation through moderate human and natural disturbances. Conclusions Yunnan has high species richness and rarity-weighted richness of Schima. Both moderate human and natural disturbances have provided regeneration niches for Schima species. Some of the Schima species studied as a second dominant (rare as the top-dominant) present in the late-successional forests. Some of them are more often as the top-dominant in early or middle successional forests, where as time goes by the dominance of Schima species would be replaced by their associated dominant taxa such as Castanopsis species.

The Chinese water pine Glyptostrobus pensilis is the sole surviving species of the genus Glyptostrobus. It is endemic to southern China, central Vietnam, and eastern Laos, and today it is nearly extinct in the wild. Forest community characteristics and population structure of G. pensilis in China have remained unknown up to now. We investigated six swamp forest stands and analyzed their forest community characteristics (i.e. vertical stratification, species composition, and diversity) and population structure, including the frequency distribution of DBH (diameter at breast height) and age-classes as found in Fujian Province, southeastern China.The vertical stratifications of all the forest stands were rather simple. The remaining wild specimens ranged from roughly 15 to some 357 years for an average of ca. 85 years, with only a few individuals less than 20 years old. Compared with the stands and populations of G. pensilis in Vietnam, the taxonomic compositions of the stands in the two regions were different, except for the dominant species-G. pensilis. The Shannon–Wiener index showed the overstory of each stand had much lower diversity (0.26 on average) in Fujian Province than that (1.97 on average) in Vietnam, whereas the diversity indices were about the same (around 2.41) for the understories in the two regions. Furthermore, we discovered 18 G. pensilis seedlings at the study sites in Fujian Province. This discovery demonstrates that G. pensilis regeneration is extremely poor and its populations are declining, although these populations are relatively healthier than those in Vietnam. Keywords: Age-class, Fujian Province, Glyptostrobus, Regeneration, Relict plant, Vietnam

We built a classification tree (CT) model to estimate climatic factors controllingthe cold temperate coniferous forest (CTCF) distributions in Yunnan provinceand to predict its potential habitats under the current and future climates, using seven climate change scenarios, projected over the years of 2070-2099. The accurate CT model on CTCFs showed that minimum temperature of coldest month (TMW) was the overwhelmingly potent factor among the six climate variables.The areas of TMW

Central Yunnan, China was once dominated by evergreen broad-leaved forests. After a long period of destructive exploitation including agriculture development, overlogging for timber and cutting for fuelwood, these forests are being allowed to reestablish themselves. A large area is now dominated by the conifer Pinus yunnanensis forest which has naturally regenerated and represents an early intermediate stage in the reestablishment of the evergreen broad-leaved forest. In 2006, a mega-fire burned approximately 18.49 km 2 of this forest. The Pinus is growing back. To examine the process of regeneration dynamics and recovery of the Pinus community after the mega-fire, we investigated plant communities in burned and unburned areas, including a P . yunnanensis shrubland regenerated after the fire, a P . yunnanensis forest without fire occurrence, a P . yunnanensis and Lithocarpus mairei mixed forest, and a Castanopsis orthacantha and Lithocarpus dealbatus evergreen broad-leaved forest, as well as a plantation of P . yunnanensis . Abundant seedlings and saplings of P . yunnanensis and some light-demanding deciduous and evergreen broad-leaved tree species were found in the Pinus shrubland five years after the fire. The frequency distribution by height-classes after the fire was of an inverse-J type, representing very good regeneration. We used space-for-time substitution to obtain an understanding of the directions and pathways of the succession. The approximate successional trend in the area was from the Pinus shrubland to the Pinus forest, then to the mixed coniferous and evergreen broad-leaved Pinus – Lithocarpus forest, then to the evergreen broad-leaved Castanopsis – Lithocarpus forest. In the early successional stage, the floristic richness and species diversity of the Pinus shrubland had lower values as compared to those in the middle and late successional stages, but much higher than those of the Pinus plantation. Our results indicate that the natural recovery of P . yunnanensis after the fire was more efficient than that of a man-made forest of the same species. Nature’s process outpaced human intervention.

The persistence of the Tertiary relict tree Tetracentron sinense Oliv. on the eastern slope of the Ailao Mountains, Yunnan, SW China, was here studied in terms of population structure (size, age) and regeneration patterns. T. sinense occurred in unstable habitats by stream banks, on steep slopes, on scree slopes, or on roadsides near streams in narrow valleys, all places subject to frequent natural disturbances, whereas none were found on stable gentle slopes free of major disturbances at similar altitudes. Further, no established saplings of T. sinense were found in forests having high bamboo (Yushania crassicollis Yi) coverage in their understory. The size and age structure of T. sinense were multimodal. The reproduction of the tree was either by means of abundant minute wind-dispersed seeds or by resprouts in unstable habitats. These populations depended on disturbance or gap regeneration to survive. T. sinense, along with other tree life-forms including evergreen broad-leaved species and conifers, dominated in the forest canopy layer, even reaching the emergent layer in places. Results of the study provide insight into the ecological characteristics and survival mechanisms of this East Asian paleoendemic tree species. The study will provide a scientific basis for recommendations for the conservation of this species and for other Tertiary relict plants having similar regeneration dynamics.