Abstract:In order to understand understory plant composition and diversity characteristics and their influencing factors in mature plantations with long-term vegetation restoration, four types of plantations (30 years old) with similar environmental conditions (slope, direction and altitude) in the Heshan National Field Research Station of Forest Ecosystem were investigated, including mixed Eucalyptus plantation (EE), Acacia mangium plantation (AM), mixed native species plantation (NS), and mixed coniferous plantation (MC), the compositions and diversities (Shannon-Wiener index, Simpson index and Pielou index) of understory vegetation were analyzed. The results showed that the types of understory plants are abundant in the plantation with vertical structure of tree-shrub-herb layers. At the shrub layer, the community composition in EE was similar to MC, so did in AM and NS. At the herb layer, the community composition was similar between EE and AM, and between NS and MC, while the community composition was significantly different between EE and MC. Stand type affected understory plant diversity. The diversity of shrub and herb in AM plantation was significantly lower than that in other three mixed forests (P<0.05), and the number of shrub species and individuals in AM plantation were the lowest. The MC plantation had the highest understory species richness. There was a positive relationship between canopy coverage and understory diversity (P<0.001). The distribution of understory vegetation was related to contents of soil nutrients, contents of different forms of nitrogen were related to the understory vegetation in EE and AM. Available phosphorus and total phosphorus contents correlated to species distribution in NS, while species distribution in MC was related to pH and total potassium. The NS plantation had the highest diversity and evenness, also the lowest dominance, performed best in maintaining the understory diversity. Therefore, the mixed forest of native tree species was more suitable for the construction of ecological public welfare forest or the stand transformation of some coniferous forest and monocultural forest of exotic tree species.

Abstract:In order to understand the effects of wind stress on coastal shelterbelt tree species, leaf morphology, photosynthetic characteristics and branch tensile resistance to long-term wind stress were studied in six coastal shelterbelt tree species, including Ligustrum lucidum, Sapindus mukorossi, Machilus thunbergii, Koelreuteria bipinnata,Sapium sebiferum, and Quercus virginiana with ages of 8-10 years. The results showed that the leaf length and leaf area of L. lucidum, S. mukorossi,M. thunbergii, K. bipinnata and Q. virginiana significantly reduced under long-term wind stress, and also did the leaf width and leaf fractal index of K. bipinnata and L. lucidum. Meanwhile, the net photosynthetic rate of all six tree species had significant inhibition for 18%-47% under long-term wind stress, and the water use efficiency of S. mukorossi, K. bipinnata and Q. virginiana decreased, but that of L. lucidum, M. thunbergii and S. sebiferum had no significant effect. Under long-term wind stress, the maximum branch load and elastic modulus of S. mukorossi, M. thunbergii and K. bipinnata significantly increased, and the positive correlation with branch diameter were further enhanced. Therefore, long-term wind stress reduced the photosynthetic capacities of coastal shelterbelt species, but trees developed adaptive strategies, such as reducing leaf area, and tolerant strategies like enhancing branch resistance to reimburse this physiological deficit. Moreover, concerning the selection and collocation of tree species for the construction and restoration of coastal shelterbelts, priority can be given to L. lucidum, M. thunbergii and S. sebiferum in areas that have been continuously stressed by the strong wind.

Abstract:To understand the release rule of lignin in the decomposition process of forest leaf litter, the lignin degradation rate of leaf litter of Pinus massoniana (P), Sassafras tzumu (S), Cinnamomum camphora (C) and Toona sinensis (T) was studied. The results showed that lignin in most of mixed litter was enriched during decomposition. The lignin content in combination of PT and PC was high in the first year, and then decreased. However, the lignin content in combination of PS, PST, PSC, PCT and PSCT were enriched at 0-6, 0-9 and 15-18 months, and decreased at other periods. At all decomposition stages, the degradation rate of lignin in some mixed litters showed synergistic effect rather than additive effect, the synergistic effect was stronger in summer and winter than in other seasons. Besides, the lignin degradation rate of PSCT6121, PSC622, PS64 and PC64 showed a synergistic effect in most decomposition stages (≥ 6/8). Therefore, the mixed leaves of P. massoniana and native broad-leaved trees promoted the degradation of lignin, the degradation of lignin in the leaf litter of P. massoniana plantation could be promoted by proper mixing with native broad-leaved species.

Abstract:To explore the application of Sapindus saponaria in ecological restoration and urban garden, a 1 hm² plot was set up in S. saponaria Fengshui Forest in Zorong Village, Longmen Town, Leizhou City, Guangdong Province, the species composition of community was analyzed, and its spatial distribution pattern and intraspecific correlation were also analyzed using a point pattern analysis with complete spatial randomness and heterogeneous poisson. The results showed that there were 3 585 individuals of 73 species, belonging to 60 genera and 28 families with diameter at the breast height (DBH) ≥ 1 cm. The proportion of the monogeneric family, single-species family and monotypic genus were obviously higher than other types, followed by the oligogenera families, oligospecies families and oligotypic genera. The spatial distribution patterns of S. saponaria showed an alternating phenomenon of aggregation, random distribution and uniform distribution at 0-25 m scales. At a small scale, the distribution of saplings was aggregated, and that of adults was uniform. With the increment of spatial scale, trees in three age classes were mainly randomly distributed. The saplings and middle-aged trees had a weak positive association at 0-25 m scales, while it was negatively associated between saplings and adult trees. The association between middle-aged and adult trees showed periodic changes, from no significant association (0-4.5 m scale) to positive association (4.5-10.0 m scale) to no association (10.0-25.0 m scale). As a consequence of neighbor competition and density dependence, the spatial distribution pattern of S. saponaria changed from aggregated distribution at small scale to random distribution at large scale. The coexisting proportion of saplings and middle aged trees was high, and that of middle-aged and adult trees at small scales also high, while saplings and adult trees are relatively independent. Therefore, S. saponaria could be cultivated in small aggregations and scattered in large scales for the ecological restoration and urban garden construction in Leizhou Peninsula.

Abstract:To reveal the genetic diversity of germplasm resources of Canarium album in China, the genetic diversity of 86 germplasms selected from the major distribution areas was studied by using ISSR and RAPD markers, and core germplasms were constructed. The results showed that 86 germplasms could be divided into 3 groups based on UPGMA genetic similarity, and 4 groups by using STRUCTURE cluster analysis, which basically conform to the regional distribution of C. album in China. The overall genetic diversity coefficient using ISSR and RAPD was 0.284±0.169 and 0.244±0.163, the percentage of polymorphism loci was 92.56% and 100%, the genetic differentiation coefficient was 0.127 and 0.142, the gene flow was 3.423 and 3.025, the average genetic similarity coefficient between populations was 0.930 and 0.939, and the average genetic similarity coefficient between individuals was 0.736 and 0.732. Therefore, it was suggested that the rich genetic diversity of C. album in China mainly caused by the genetic differentiation or variation among individuals, and there were obvious regional differences.

Abstract:In order to select good provenance and family, the genetic characteristics in growth and wood properties associated with pulp wood of eight-year-old Eucalyptus pellita from different provenances in Guangxi Dongmen State Forest Farm were studied. The results showed that the average length and width of wood fiber was 590.9 and 28.9 μm, the fiber aspect ratio was 20.34 with kink index of 0.29, and the aspect ratio and kink index of sapwood fiber were larger than those of heartwood. There were very significant positive correlations between DBH and tree height, density with fiber length-width ratio and kink index, as well as kink index with length-width ratio of sapwood fiber, while kink index was very significant negative correlation with length-width ratio of heartwood fiber. So, according to principal component analysis (PCA), the provenances 4, 13, 10 were excellent, and 25 families were good, in which 146, 084 and 53-11 families were the top three.

Abstract:To reveal the formation mechanism of fruit flavor in Morinda citrifolia, the activity and expression pattern of fructokinase (FRK) gene during fruit development were studied. The results showed that the contents of fructose, sucrose and glucose in fruit of M. citrifolia accumulated with the development of fruit, and reached the highest when the fruit was fully mature, while the activity of fructokinase decreased with the development of the fruit. The fructokinase gene TRINITY_DN17192_c0_g1, named as McFRK2 was cloned from M. citrifolia fruit, with 984 bp ORF, encoding 327 amino acids, and the GenBank accession number was MW380742. The amino acid sequence of McFRK2 was similar to that of FRK2 of coffee (Coffea arabica) at 98%. By using qRT-PCR, the expression of McFRK2 decreased gradually during fruit development. When the fruit was ripe, the expression of McFRK2 tended to be stable, which was consistent with the change trend of fructokinase activity. Therefore, McFRK2 might be involved in glucose metabolism by regulating fructokinase activity in fruits, which plays an important role in regulating fruit flavor formation.

Abstract:In order to understand the successful invasion mechanism of Mikania micrantha in forest community, the stem elongation characteristics, photosynthetic characteristics and changes in growth regulators of M. micrantha under shade were studied by simulating low light under forest (30% natural light). The results showed that the contents of cytokinin, gibberellin and auxin increased significantly in stem under low light, and the net photosynthetic rate (P_n) of stem was still very high at (1.22±0.13)μmol/(m²·s). Therefore, M. micrantha maintained a high photosynthetic efficiency to provide material basis for rapid elongation of stem and synthesized more growth regulators to control the redistribution of substances and allocate more biomass to the stem, so as to enable the stem to elongate rapidly under low light, which was one of the important factors forM. micrantha to overcome the limitation of low light and then successfully invaded.

Abstract:To understand the difference in chemical properties between drought-dead and natural litter leaves, the chemistry traits in leaves of five species in Yuanjiang Savanna Ecosystem Research Station, such as Bauhinia brachycarpa, Tarenna depauperate, Cipadessa baccifera, Polyalthia cerasoides and Rubus pungens, were studied. The results showed that the chemical characteristics of carbon and nutrients had great variation between drought-dead and natural litter leaves, and there were very significant differences among these tree species (P<0.001). Compared with natural litter leaves, drought-dead leaves had high dissolved organic carbon, C/N and magnesium, but the concentration of lignin, hemicellulose and nitrogen was low. Furthermore, the chemical traits of drought-dead leaves had positive correlation with nature litter leaves, such as the concentration of carbon (R²=0.56,P<0.01), cellulose (R²=0.52, P<0.01), hemicellulose (R²=0.85, P<0.001), tannin (R²=0.99,P<0.001), lignin/N (R²=0.60,P<0.01), C/N (R²=0.64,P<0.001) and nitrogen (R²=0.85, P<0.001). Therefore, according to the chemical properties of natural litters, the chemical properties of drought-dead leaves under extreme drought conditions could be predicted in the future.

Abstract:To investigate the effects of mycorrhizal fungi on the growth of Paphiopedilum hirsutissimum, four strains, such as Cladosporium perangustum, Kirschsteiniothelia tectonae, Phialophora sp. and Cyphellophora sp., isolated from roots of wild Paphiopedilum, were inoculated to tissue-cultured and potting seedlings of P. hirsutissimum for 120 days, and then the changes in growth and physiological characters were studied. The results showed that the biomass and physiological indexes of tissue-cultured seedlings increase inoculated with Cladosporium perangustum and Phialophora sp., the fresh weight, activities of three protective enzymes, and total chlorophyll content had significant differences compared with the control. Especially the fresh weight was more than control for 360%-380%. Two strains, Kirschsteiniothelia tectonae and Phialophora sp. had the best effect for the potting seedlings, which the fresh weight, leaf area, and activities of three protective enzymes had significant difference compared with the control, and the fresh weight increased 261%-330% than control. Therefore, appropriate strains could be inoculated to P. hirsutissimum at different growth stages in actual production. Phialophora sp., which showed a good promoting effect on P. hirsutissimum, could be developed as a universal beneficial bacterial agent in seedling stage.

Abstract:In order to explore the effect of NAA on cutting rooting of Blumea balsamifera, the changes in physiological and biochemical characteristics of 4-year-old healthy branches as cuttings were studied treated with 500 mg/L NAA. The results showed that rooting rate was positively correlated with endogenous IAA, GA content and IAA/ABA, but negatively with ABA content. The IAA content of cuttings increased and ABA content decreased treated with NAA, showing that NAA had helped with adventitious roots. The rooting rate of cuttings was positively correlated with PPO activity and negatively with IAAO activity, and NAA could enhance PPO activity and reduce IAAO activity of cuttings, which is beneficial to rooting. The contents of soluble protein and total soluble sugar were positively correlated with rooting rate. NAA could promote the accumulation of total soluble sugar and soluble protein, improve the cell differentiation and metabolic ability of cuttings. Therefore, 500 mg/L NAA could promote the growth and development of adventitious roots.

Abstract:In order to understand the effect of plant growth regulators on flowering of Phalaenopsis, the changes in endogenous hormone contents and influence of growth regulators in ‘Big Chilli’ and ‘Fullers Sunset’ were studied during flowering. The results showed that the flower bud differentiation process of Phalaenopsis included inflorescence primordium differentiation, floret primordium differentiation, calyx differentiation, petal differentiation, stamen column (stamen and carpels) and labellum differentiation. During the inflorescence primordium differentiation stage, ABA and IAA with high level inhibited vegetative growth, and the level droped after flowering and rose again after flower development. GA₃and ZR could promote cell differentiation and division. Spraying GA₃ could advance flowering and significantly increase stalk length, while spraying 6-BA could significantly improve the double stem rate of ‘Fullers Sunset’. Therefore, at the flowering stage, Phalaenopsis could be properly sprayed with growth regulators to regulate the flowering stage and the amount of flowers.

Abstract:To understand floristic characteristics of bryophytes in Niangniang Mountain National Wetland Park, Liupanshui, the species composition of bryophytes and migration routes of Chinese Endemic were studied. The results showed that there were 266 species (including 12 varieties), belonging to 51 families and 106 genera, including 2 vulnerable species. The bryophyte floristic could be divided into 17 areal-types, the North Temperate (17.37%) was dominant, followed by the Tropical Asia (14.83%). There were more species belonging to tropical areal-types (73 species, R) than temperate areal-types (65 species, T), the R/T was 112.31%. It has the characteristics of the warm-temperate zone to the middle-subtropical zone. Compared with 11 neighboring regions, the bryophytes floristic spectrum of Niangniang Mountain was the most closest to that of Bada Mountain, followed by that of Leigong Mountain. These results showed that the bryoflora of Niangniang Mountain corresponded to its geographical location. The Chinese Endemic of bryophytes was of Himalayan origin and mainly migrate eastward and northward. The migration routes of bryophytes Chinese Endemic was the most similar to Cibagou, the reasons might be related to geographical location, climate and its own biological characteristics.

Abstract:Fellhanera mastothallina (Vain.) Lücking & Sérus. was reported as a newly recorded species from China based on the foliicolous lichen specimens collected from Hainan Province. The characteristics of morphology, anatomy and chemistry were provided with microstructure photos. It was characterized by the crustose thallus with light green to orange-red verrucosa, brown apothecia, external exciple prosoplecten-chymatous and narrowly clavate ascospores tapering towards proximal end, (3–)7-septate, 26–36 µm×2–3 µm. The phylogenetic tree based on the mtSSU region showed that it had close relationship with the type species F. fuscatula (Müll. Arg.) Vězda. A key to known Chinese Fellhanera species was also provided.

Abstract:Didymoplexis striata J.J. Sm. was reported as a newly recorded species from China. It was found during a field investigation in Huishan Provincial Nature Reserve, Hainan Province. The species could be differentiated from all other species of this genus by the following combination of characters:a perianth tube with longitudinally light brown stripes on the adaxial surface, entire lip with a pale yellowish median thickening band. In this paper, its morphological descriptions, color photos, distribution, and conservation status are provided.

Abstract:In order to excavate the development and utilization potential of Michelia champaca leaves, the bioactivity and chemical composition of ethanol extract from leaves obtained by ultrasonic extraction were studied. The results showed that 20% and 80% ethanol extracts had antioxidant potential ability by using DPPH∙ free radical scavenging assay and reducing power of iron ion. There was cytotoxicity to HacaT cells, when the concentration of 20% or 80% extracts was more than 12.5 or 6.25 μg/mL, respectively. A total of 206 compounds were obtained from ethanol extract from M. champaca leaves by UPLC-MS combined with software spectrum library, including flavonoids, alkaloids, fatty acids, alcohols and so on. Among the flavonoids, rutin, quercetin and kaempferol could be identified clearly by standard product verification. The contents of compounds in ethanol extracts of M. champaca leaves were different among different months, and the distribution of components in spring and summer were significantly different from that in autumn and winter. Besides, some compositions had seasonal characteristics. In conclusion, Michelia champaca leaves had potential in the development of daily chemical products, and the harvest time could be selected according to the actual composition.

Abstract:To study triterpenes from Akebia trifoliata and its antibacterial activities, nine triterpenes were isolated from the ethanol extract by various methods, such as silica gel, ODS, Sephadex LH-20 column chromatography and semi-preparative HPLC. Based on physical and chemical properties and spectral data, their structures were identified as stachlic acid A (1), oleanolic acid (2), ursolic acid (3), 2α,3β-dihydroxyolean-13(18)-en-28-oic acid (4), serratagenic acid (5), gypsogenic acid (6), 20α-hydroxyl-29-noroleanolic acid (7), mesembryanthemoidigenic acid (8) and 12α-hydroxy-δ-lactone (9). The compounds 2 and 3 had strong antibacterial activity against three tested bacterial strains in vitro. Compounds 1,4, 6 and 9 were isolated from A. trifoliata for the first time, compounds 3 and 7 were isolated from genus Akebia for the first time.