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Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005-2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest. Copyright © 2013 Cambridge University Press.

Euryodendron excelsum is in a monotypic genus Euryodendron , endemic to China. It has intermediate morphisms in the Pentaphylacaceae or Theaceae families, which make it distinct. Due to anthropogenic disturbance, E. excelsum is currently found in very restricted and fragmented areas with extremely small populations. Although much research and effort has been applied towards its conservation, its long-term survival mechanisms and evolutionary history remain elusive, especially from a genomic aspect. Therefore, using a combination of long/short whole genome sequencing, RNA sequencing reads, and Hi-C data, we assembled and annotated a high-quality genome for E. excelsum. The genome assembly of E. excelsum comprised 1,059,895,887 bp with 99.66% anchored into 23 pseudo-chromosomes and a 99.0% BUSCO completeness. Comparative genomic analysis revealed the expansion of terpenoid and flavonoid secondary metabolite genes, and displayed a tandem and/or proximal duplication framework of these genes. E. excelsum also displayed genes associated with growth, development, and defence adaptation from whole genome duplication. Demographic analysis indicated that its fluctuations in population size and its recent population decline were related to cold climate changes. The E. excelsum genome assembly provides a highly valuable resource for evolutionary and ecological research in the future, aiding its conservation, management, and restoration. [ABSTRACT FROM AUTHOR]

Ormosia is a genus of the Fabaceae family that shows a distinct evolutionary history due to its typical Asian-American tropical disjunction distribution pattern. However, both its phylogeny and biogeographic mechanisms have not been fully resolved. In addition, Ormosia species have great economic and ecological potential in the wood and handicraft (using their attractive seeds) industries, reforestation, and folk medicine (due to their flavonoids, alkaloids, and terpenoids), making them highly valuable in research, especially from a genomic perspective. We report the genome assemblies of two common Ormosia species, Ormosia emarginata and Ormosia semicastrata, in South China, using both long and short sequencing reads. The genome assemblies of O. emarginata and O. semicastrata comprised 90 contigs with a total length of 1,420,917,605 bp and 63 contigs with a total length of 1,511,766,959 bp, respectively. Benchmarking Universal Single-Copy Orthologs (BUSCO) assessment revealed 97.0% and 98.3% completeness of the O. emarginata and O. semicastrata assemblies, respectively. The assemblies contain 48,599 and 52,067 protein-coding genes, respectively. Phylogenetic analyses using 1032 single-copy genes with 19 species indicated that they are closely related to Lupinus albus. We investigated genes related to plant hormones, signaling, the circadian rhythm, transcription factors, and secondary metabolites derived from the whole genome and tandem and proximal duplications, indicating that these duplications should play important roles in the growth, development, and defense of Ormosia species. To our knowledge, our study is the first report on Ormosia genome assemblies. This information will facilitate phylogenetic and biogeographic analyses and species breeding in the future. [ABSTRACT FROM AUTHOR]

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Feng Shui woodlands are naturally or artificially formed green areas in southern China. They are precious for maintaining ecosystem balance in modern semiurban environments. However, they are generally small and geographically isolated from each other, and the status of genetic diversity of the plant species within them has been almost neglected. Therefore, we studied the genetic diversity of the endangered Erythrophleum fordii in eight Feng Shui woodlands (a total of 1,061 individuals) in Guangzhou, a large city in southern China, using microsatellites. For comparison, one population with 33 individuals sampled in a nature reserve was also studied. Although our results indicate that significant demographic declines occurred historically in E. fordii, such declines have not resulted in consistent reductions in genetic variation over generations in Feng Shui populations in the recent past, and the levels of genetic variation in these populations were higher than or comparable to the genetic variation of the population in the nature reserve. In addition, our parentage and paternity analyses indicated widespread and potential long‐distance pollen flow within one Feng Shui woodland, indicating the presence of an unbroken pollination network, which would at least partially alleviate the genetic erosion due to habitat fragmentation and the unequal gene contributions of E. fordii parents to their progenies when favorable recruitment habitats are absent under most of the parent trees. Overall, our results suggest that E. fordii in Feng Shui woodlands may not be driven to extinction in the near future. Nevertheless, uncontrolled fast urban development with a lack of awareness of Feng Shui woodlands will cause the local extinction of E. fordii, which has already happened in some Feng Shui woodlands. [ABSTRACT FROM AUTHOR]