A DNA barcode library for woody plants in tropical and subtropical China.

The application of DNA barcoding has been significantly limited by the scarcity of reliable specimens and inadequate coverage and replication across all species. The deficiency of DNA barcode reference coverage is particularly striking for highly biodiverse subtropical and tropical regions. In this study, we present a comprehensive barcode library for woody plants in tropical and subtropical China. Our dataset includes a standard barcode library comprising the four most widely used barcodes (rbcL, matK, ITS, and ITS2) for 2,520 species from 4,654 samples across 49 orders, 144 families, and 693 genera, along with 79 samples identified at the genus level. This dataset also provides a super-barcode library consisting of 1,239 samples from 1,139 species, 411 genera, 113 families, and 40 orders. This newly developed library will serve as a valuable resource for DNA barcoding research in tropical and subtropical China and bordering countries, enable more accurate species identification, and contribute to the conservation and management of tropical and subtropical forests.

Plastome-based phylogeny improves community phylogenetics of subtropical forests in China.

Phylogenetic trees have been extensively used in community ecology. However, how the phylogeny construction affects ecological inferences is poorly understood. In this study, we constructed three different types of phylogenetic trees (a synthetic-tree generated using V.PhyloMaker, a barcode-tree generated using rbcL+matK+trnH-psbA, and a plastome-tree generated from plastid genomes) that represented an increasing level of phylogenetic resolution among 580 woody plant species from six forest dynamic plots in subtropical evergreen broadleaved forests of China. We then evaluated the performance of each phylogeny in estimations of community phylogenetic structure, turnover and phylogenetic signal in functional traits. As expected, the plastome-tree was most resolved and most supported for relationships among species. For local phylogenetic structure, the three trees showed consistent results with Faith's PD and MPD; however, only the synthetic-tree produced significant clustering patterns using MNTD for some plots. For phylogenetic turnover, contrasting results between the molecular trees and the synthetic-tree occurred only with nearest neighbor distance. The barcode-tree agreed more with the plastome-tree than the synthetic-tree for both phylogenetic structure and turnover. For functional traits, both the barcode-tree and plastome-tree detected phylogenetic signal in maximum height, but only the plastome-tree detected signal in leaf width. This is the first study that uses plastid genomes in large-scale community phylogenetics. Our results highlight the improvement of plastome-trees over barcode-trees and synthetic-trees for the analyses studied here. Our results also point to the possibility of type I and II errors in estimation of phylogenetic structure and turnover and detection of phylogenetic signal when using synthetic-trees.

[Species composition, structure, and spatial distribution of shrubs in broad-leaved Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains].

Based on the shrub census of 600 quadrats (5 mx5 m) in a 25 hm2 plot of broad-leaved Korean pine mixed forest in Changbai Mountains, this paper analyzed the species composition, structure, and spatial distribution of shrubs in the forest. A total of 18 shrub species, including 6435 shrub individuals and 11369 stems, were found in the census, with Philadelphus schrenkii, Corylus mandshurica, and Acer barbinerve being the dominant species. P. schrenkii had the highest amounts of individuals and stems, occupying 40.6% and 33.4% of the total, respectively. There existed great differences in the clumpy ratio, stem number per clump, crown size, and basal diameter among the shrub species, and the height of different shrub species also varied significantly, with obvious vertical stratification observed in the community. The dominant species P. schrenkii had a wide distribution, while Sorbaria sorbifolia, Spiraea chamaedryfolia, S. salicifolia, and Euonymus pauciflorus had obvious heterogeneous distributions.

[Composition and seasonal dynamics of litter falls in a broad-leaved Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains, Northeast China].

In order to understand the composition and spatiotemporal dynamics of the litter falls at community level in a broad-leaved Korean pine mixed forest in Changbai Mountains, litter falls were collected from 150 containers in a 25 hm2 permanent plot in 2008. The leaf litters in the containers were from 35 tree species, accounting for 67.3% of the total number (52) of the tree species with DBH > or =1 cm in the plot. The litter falls had a weight 29.39 kg, equivalent to 3918.4 kg x hm(-2) among which, broad leaves, miscellany, needle leaves, and branches occupied 61.7%, 18.0%, 11.7%, and 8.6%, respectively. About 83.8% of the broad leaves were from Tilia amurensis, Fraxinus mandshurica, Quercus mongolica, Acer mono, and Ulmus japonica. The litter falls showed an evident seasonal dynamics, with the peaks occurred from 13 September to 10 October, e.g., the litter falls from T. amurensis and Pinus koraiensis peaked in 13-26 September, while those from Q. mongolica, U. japonica, and A. pseudo-sieboldianum peaked in 27 September to 10 October. There was a great difference in the mass of the litter falls among the containers, e.g., with 150-200 g litters in 68 containers and >500 g litters in 1 container. The species number of the litter falls in a container was 18 in maximum, and was 12 in common (32 containers). Litter falls mass was positively proportional to the sum of the basal area at breast height of parent trees in the plot, and the amount of the litter falls in the containers was related with the locations of the containers, exhibiting an evident spatial heterogeneity in the plot.

[Pinus koraiensis seed consumption by rodents and birds].

An investigation from 2006 to 2007 was made on the Pinus koraiensis seed consumption by rodents and birds in the broad-leaved P. koraiensis mixed forest and birch forest at the same altitude in Changbai Mountains. The results showed that in broad-leaved P. koraiensis mixed forest, rodents consumed more pinecone seeds than birds; while in birch forest, birds did more than rodents. In the two forests, the total number of pinecone seeds consumed by rodents was significantly higher than that consumed by birds (P < 0.01). In addition, rodents consumed more embedded seeds in broad-leaved P. koraiensis mixed forest than in birch forest, and the consumption amount in the two forests decreased with increasing embedded depth.

[Seasonal dynamics and spatial distribution patterns of herbs diversity in broadleaved Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains].

In this paper, the species composition, seasonal dynamics, and spatial distribution patterns of herbs were examined in a 25 hm2 broadleaved Korean pine (Pinus koraiensis) mixed forest plot in Changbai Mountains. The results showed that the plot had a relatively high herbaceous richness, with 102 species belonging to 40 families and 84 genera, and the Shannon index, Simpson index, and Pielou index was 3.52, 0.96 and 0.75, respectively. The three indices varied dramatically with growth season, whereas the species abundance decreased linearly from early spring to autumn. The species richness and abundance showed irregular distribution, indicating that herbaceous species were microenvironment-dependent. Slope aspect had significant effects on herbaceous species richness and abundance. Northern and eastern slopes had higher species richness and abundance in early spring than southern and western slopes, whereas it was in adverse in late summer and autumn.

[Spatial distribution patterns and associations of Pinus koraiensis and Tilia amurensis in broad-leaved Korean pine mixed forest in Changbai Mountains].

Based on the investigation data from a 25 hm2 broadleaved Korean pine (Pinus koraiensis) mixed forest plot in Changbai Mountains of China, the dominant species Korean pine and Tilia amurensis were chosen as research objects. One point pattern analysis method, O-ring statistics, was used to analyze the spatial patterns of the species in three vertical layers, i. e., overstory, midstory and understory layers, and the spatial associations of intra- and inter-species between different vertical layers were studied. The results showed that P. koraiensis and T. amurensis were clumped at smaller scales. Higher layers tended to be randomly or regularly distributed, while lower layers tended to be aggregated at smaller scales. The aggregation degree decreased with canopy height. P. koraiensis stems in overstory layer were significantly positively associated to the stems in midstory layer at scales < 11 m, and T. amurensis in overstory layer showed negatively correlation with that in midstory and understory layers. There was generally a positive correlation between the two species, but the association varied among different layers. No significant correlation was observed between P. koraiensis stems in overstory layer and T. amurensis in three layers. P. koraiensis stems in midstory layer showed slightly negative correlation with T. amurensis in the same layer at scales > 4 m, but no significant association to T. amurensis in understroy layer. T. amurensis in overstory layer was significantly positively associated to P. koraiensis in midstory layer at scales < 100 m.