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Many areas are affected by the monsoon because of different sea and land positions. At the same time, the blocking effect of a mountain range forms different habitats on both sides of the mountain range. However, the distribution mechanism of woody plants is unclear in mountain forest ecosystems influenced by topography and monsoons. In this study, 10 plots, each with an area of 1 hm2 (100 m × 100 m), were randomly established on the south and north aspects of a mountain forest. We examined community structure differences and distribution preferences of woody plants on both sides of the mountain. Our findings were as follows: (1) The characteristics of woody plant assemblages differed among various aspects. (2) Network analysis showed that specialization index was 0.186 and modularity index was 0.235, and the torus translation test showed that a total of 45 species were detected to be associated with at least one of the habitats (45/106, 42.45%). (3) The community stability of the south aspect was higher than that of the north aspect. Our findings suggest that the distribution of woody plants among different aspects was specialized and not random in alpine forest ecosystems. This study contributes to a clear understanding of the distribution mechanism of woody plants in mountain forest ecosystems influenced by topography and monsoons.

The relationships among topography, topographically-driven habitats, dominant species and vertical layers in forest ecosystem are often complicate. In this study, based on the five 1 ha forest dynamics plots in China, we examined these relationships in different communities of temperate forest in China through structural equation model and torus-translation test. Our results showed that (1) the dominant species is an important factor that affects the forest vertical layers; (2) interspecific competition is prevalent between dominant species and canopy layer; (3) the species in each vertical layer have varying topographical habitat preferences. These findings shed new light to the species coexistence among forest vertical layers in temperate forest.

The habitat partitioning hypothesis provides a conceptual framework for explaining the maintenance of plant and animal diversity. Its central tenet assumes environmental conditions are spatially structured, and that this structure is reflected in species distributions through associations with different habitats. Studies confirming habitat partitioning effects have focused primarily on spatial distributions of plants and animals, with habitat partitioning hypothesis under explored for macrofungi. Here, we examined the sporocarps of macrofungi in a 5-ha forest dynamics plot in China. We used four different methods to define microhabitats for habitat partitioning analyses based on topography, understory light availability, plant community, or a combination of these factors, and analyzed the effect of microhabitat partitioning on epigeous macrofungal community. Our results showed that the characteristics of the macrofungal assemblages varied among the habitats. A total of 85 species examined were associated with one or more of the habitat types (85/125, 68%). The factors related to the sporocarp composition differed among the various microhabitats. Our findings suggest that different microhabitats favor occurrence of different macrofungal species, and sporocarps -environment relation varied among the different microhabitats at this temperate mountain forest locality. These findings shed new light to the biodiversity conservation in macrofungi in temperate deciduous broad-leaved forest and point to the potential importance of microhabitat partitioning for sporocarp formation.

Congeneric species often have similar ecological characteristics and use similar resources. These similarities may make it easier for them to co-occur in a similar habitat but may also lead to strong competitions that limit their coexistence. Hence, how do similarities in congeneric species affect their coexistence exactly? This study mainly used spatial point pattern analysis in two 1 hm2 plots in the Baotianman National Nature Reserve, Henan, China, to compare the similarities in spatial distributions and interspecific associations of Quercus species. Results revealed that Quercus species were all aggregated under the complete spatial randomness null model, and aggregations were weaker under the heterogeneous Poisson process null model in each plot. The interspecific associations of Quercus species to non-Quercus species were very similar in Plot 1. However, they can be either positive or negative in different plots between the co-occurring Quercus species. The spatial distributions of congeneric species, interspecific associations with non-Quercus species, neighborhood richness around species, and species diversity were all different between the two plots. We found that congeneric species did have some similarities, and the closely related congeneric species can positive or negative associate with each other in different plots. The co-occurring congeneric species may have different survival strategies in different habitats. On the one hand, competition among congenerics may lead to differentiation in resource utilization. On the other hand, their similar interspecific associations can strengthen their competitive ability and promote local exclusion to noncongeneric species to obtain more living space. Our results provide new knowledge for us to better understand the coexistence mechanisms of species.

Species turnover patterns can be inconsistent due to differences in the dispersal ability of different growth forms. Here, species of trees, shrubs, herbs, and bryophytes in the Xiaoqinling National Nature Reserve in China were analyzed to determine patterns of species turnover along an elevation and spatial gradient. Variance partitioning was used to assess the relative contribution of topographic heterogeneity and dispersal limitation to species turnover. Our results suggest that the effect of dispersal limitation is more important than topographic heterogeneity on species turnover in temperate mountane ecosystems in the study area. Dispersal limitation has a greater effect on trees species turnover than on shrubs, herbs or bryophytes species turnover.

Elucidating the major drivers of bryophyte distribution is the first step to protecting bryophyte diversity. Topography, forest, substrates (ground, tree trunks, roots, rocks, and rotten wood), and spatial factor, which factors are the major drivers of bryophyte distribution? In this study, 53 plots were set in 400 m2 along the elevation gradient in Xiaoqinling, China. All bryophytes in the plots were collected and identified. Regression analysis was used to examine the relationship between bryophyte and substrate diversity. We compared the patterns of overall bryophyte diversity and diversity of bryophytes found on the ground, tree, and rock along elevational gradients. Canonical correspondence analysis was applied to relate species composition to selected environmental variables. The importance of topography, forest, substrates, and spatial factors was determined by variance partitioning. A total of 1378 bryophyte specimens were collected, and 240 species were identified. Bryophyte diversity was closely related to substrate diversity. The overall bryophyte diversity significantly increased with elevation; however, the response varied among ground, tree, and rock bryophytes. Tree diversity and herb layer were considered important environmental factors in determining bryophyte distribution. Species abundance was best explained by stand structure (17%), and species diversity was best explained by stand structure (35%) and substrate (40%). Results directly indicated that substrate diversity can improve bryophyte species diversity. The effects of micro-habitat formed by stand structure and substrate diversity were higher than those of spatial processes and topography factors on bryophyte distribution. This study proved that the determinant factors influencing bryophyte diversity reflect the trends in recent forest management, providing a real opportunity to improve forest biodiversity conservation.

Based on tree-ring analysis, Pinus armandii trees were divided into three classes (A, DBH≤15 cm; B, 15 cm 25 cm) to study carbon storage dynamics of Pinus armandii populations in the Baotianman National Nature Reserve. Comparison of these three diameter classes revealed three major findings. (1) The carbon storage of P. armandii trees in small DBH class A, intermediate class B and large class C were 2.757, 9.211 and 15.408 t/hm2, respectively, with corresponding annual carbon increments of 0.0685, 0.1535 and 0.136 t/hm2. (2) The intermediate class (15 cm P. armandii forest. (3) Trees in the large DBH class (DBH>25 cm) had the greatest contribution to total carbon storage of the P. armandii forest. Tree mortality was the main factor limiting carbon storage within small and intermediate DBH class P. armandii trees, whereas physiological growth was the restrictive factor for large DBH class trees. Our results demonstrate that dendrochronological analysisis is an important method to evaluate growth trends and to assess the carbon storage dynamics of the P. armandii forest in the Baotianman National Nature Reserve.

Abies kawakamii is endemic to the island of Taiwan and has been listed as a threatened species in the Red List. In present study, we reported the complete chloroplast genome of A. kawakamii. The chloroplast genome is 121,290 bp in size. It was composed of 114 genes and they were 68 peptide-encoding genes, 35 tRNA genes, four rRNA genes, six open reading frames and one pseudogene. Loss of ndh genes was identified in the genome of A. kawakamii. Inverted repeat sequences include trnS–psaM–ycf12–trnG and trnG–ycf12–psaM–trnS were recognized in 52-kb inversion points. The phylogenetic analysis confirms that the Abies species are strongly supported as monophyletic. The complete plastome of A. kawakamii will provide potential genetic resources for further conservation and management strategies.

Congeneric species often have similar ecological characteristics and use similar resources. These similarities may make it easier for them to co‐occur in a similar habitat but may also lead to strong competitions that limit their coexistence. Hence, how do similarities in congeneric species affect their coexistence exactly? This study mainly used spatial point pattern analysis in two 1 hm2 plots in the Baotianman National Nature Reserve, Henan, China, to compare the similarities in spatial distributions and interspecific associations of Quercus species. Results revealed that Quercus species were all aggregated under the complete spatial randomness null model, and aggregations were weaker under the heterogeneous Poisson process null model in each plot. The interspecific associations of Quercus species to non‐Quercus species were very similar in Plot 1. However, they can be either positive or negative in different plots between the co‐occurring Quercus species. The spatial distributions of congeneric species, interspecific associations with non‐Quercus species, neighborhood richness around species, and species diversity were all different between the two plots. We found that congeneric species did have some similarities, and the closely related congeneric species can positive or negative associate with each other in different plots. The co‐occurring congeneric species may have different survival strategies in different habitats. On the one hand, competition among congenerics may lead to differentiation in resource utilization. On the other hand, their similar interspecific associations can strengthen their competitive ability and promote local exclusion to noncongeneric species to obtain more living space. Our results provide new knowledge for us to better understand the coexistence mechanisms of species.

Species turnover is fundamental for understanding the mechanisms that influence large-scale species richness patterns. However, few studies have described and interpreted large-scale spatial variation in plant species turnover, and the causes of this variation remain elusive. In addition, the determinants of species turnover depend on the dispersal ability of growth forms. In this study, we explored the large-scale patterns of woody species turnover across the latitude gradient based on eight large stem-mapping plots (covering 184 ha forest) in East Asia. The patterns of woody species turnover increased significantly with increasing latitude differences in East Asia. For overall woody species, environment explained 36.30%, 37.20%, and 48.48% of the total variance in Jaccard’s (βj), Sorenson’s, (βs), and Simpson’s dissimilarity (βsim). Spatial factors explained 47.92%, 48.39%, and 41.38% of the total variance in βj, βs, and βsim, respectively. The effects of pure spatial and spatially structured environments were stronger than pure environmental effects for overall woody species. Our results support the hypothesis that the effect of neutral processes on woody species turnover is more important than the effect of the environment. Neutral processes explained more variation for turnover of tree species, and environmental factors explained more variation for the turnover of shrub species on a large scale. Therefore, trees and shrubs should be subjected to different protection strategies in future biodiversity conservation efforts.

Point pattern analysis of species in a community is important in gaining a better understanding of the underlying ecological processes controlling the observed structure. In this paper, univariate and bivariate spatial point pattern analysis based on the pair-correlation function were used to evaluate the spatial patterns of Quercus variabilis. We compared the spatial patterns and associations of Q. variabilis at four different growth stages, and the relationships between standing trees and snags of Q. variabilis in two fully-mapped 1-ha forest plots in the Baotianman National Nature Reserve. We found that: (1) Aggregation was the main pattern type of Q. variabilis in the plots, with one plot showing stronger aggregation and the other exhibiting more randomness. (2) At different growth stages of Q. variabilis in the two plots, aggregation was found in younger stages and randomness in the older. (3) Positive interactions were found between the different growth stages of Q. variabilis in Plot I, and negative interactions in Plot II. (4) There are positive associations between standing trees and snags of Q. variabilis in Plot I, and spatial segregation in Plot II. Our study sug- gests that the spatial distribution of Q. variabilis may be influenced by environmental heterogeneity. This is important because the spatial distribution of this species in turn affects self regeneration of Q. variabilis

Metal nanoparticle–chitosan (NPs–chitosan) bioconjugates were formed by exposure of chitosan to an aqueous solution of metal salts under thermal treatment. The metal nanoparticles that are formed strongly bound to chitosan, which encouraged us to investigate their catalytic performance. It was demonstrated that the metal NPs–chitosan bioconjugates functioned as effective catalysts for the reduction of 4-nitrophenol in the presence of NaBH 4 , which was monitored by means of spectrophotometry as a function of reaction time. The silver NPs–chitosan bioconjugates exhibited excellent catalytic activity and were reusable for up to seven cycles. In contrast, the gold NPs–chitosan catalyst displayed poor catalytic activity, even in the second cycle. A highlight of our approach is that chitosan simultaneously acts as an active support for the synthesis and assembly of nanoparticles, and the resultant bioconjugates bear the advantage of easy separation from the reaction medium.

A gold nanoparticles-based (GNPs-based) assay was developed for evaluating antioxidant activity of chrysanthemum extracts and tea beverages. Briefly, a GNPs growth system consisted of designated concentrations of hydrogen tetrachloroaurate, cetyltrimethyl ammonium bromide, sodium citrate, and phosphate buffer was designed, followed by the addition of 1 mL different level of test samples. After a 10-min reaction at 45°C, GNPs was formed in the reduction of metallic ions to zero valence gold by chrysanthemum extracts or tea beverages. And the resultant solution exhibited a characteristic surface plasmon resonance band of GNPs centered at about 545 nm, responsible for its vivid light pink or wine red color. The optical properties of GNPs formed correlate well with antioxidant activity of test samples. As a result, the antioxidant functional evaluation of chrysanthemum extracts and beverages could be performed by this GNPs-based assay with a spectrophotometer or in visual analysis to a certain extent. Our present method based on the sample-mediated generation and growth of GNPs is rapid, convenient, inexpensive, and also demonstrates a new possibility for the application of nanotechnology in food science. Moreover, this present work provides some useful information for in-depth research of involving chrysanthemum.

Chitosan has natural abundance, unique bioactivity and attractive physicochemical properties. Recent years, the synthesis of chitosan-based metal nanomaterials has attracted increasing attention. The synthesis of metal nanoparticles utilizing biomolecular or organism offers a mild medium, and thus a greater degree of control over the nanoparticles produced, along with higher reproducibility. In particular, preparation of metal nanoparticles based on biomolecular or organism has its unique facility in integrating "minimum feature sizes" into labile biological components to an excellent synergy and bifunctional effect and consequently a more broad application. Herein, we review the new development of chitosan, chitosan-based synthesis of metal nanomaterials, and their application.

Chitosan-based silver nanoparticles were synthesized by reducing silver nitrate salts with nontoxic and biodegradable chitosan. The silver nanoparticles thus obtained showed highly potent antibacterial activity toward both Gram-positive and Gram-negative bacteria, comparable with the highly active precursor silver salts. Silver-impregnated chitosan films were formed from the starting materials composed of silver nitrate and chitosan via thermal treatment. Compared with pure chitosan films, chitosan films with silver showed both fast and long-lasting antibacterial effectiveness against Escherichia coli. The silver antibacterial materials prepared in our present system are promising candidates for a wide range of biomedical and general applications.