[Phenotypic variations in cones and seeds of natural Cupressus chengiana populations in China].[Pubmed: 29740999]

运用巢式方差分析、变异系数、表型分化系数和聚类分析等多种分析方法,研究了11个岷江柏种群的13个种实表型性状在种群内和种群间的变异及其与环境因子间的关系,并对其进行了类群划分.结果表明: 岷江柏种实表型性状在种群间和种群内均存在显著差异,种群内的变异(49.7%)大于种群间的变异(28.6%),种间平均分化系数为43.4%,分化程度相对较大.球果质量的平均变异系数最高(37.2%),其次是单个球果种子质量,球果长的平均变异系数最小(8.0%),是最稳定的种实性状.康定县的表型多样性最丰富,武都县的最小.在岷江柏的研究区内,最热月的平均气温和生长季的水分条件是其种实表型的主要限制因子.依据13个种实表型性状将11个岷江柏天然种群分为2类3亚类,基本上代表了3个流域的种群分布情况.大渡河流域种群种实表型性状最佳,岷江流域最差.

[Dynamics of carbon and nitrogen storage of Cupressus chengiana plantations in the arid valley of Minjiang River, Southwest China].[Pubmed: 26259452]

The carbon and nitrogen storage and distribution patterns of Cupressus chengiana plantation ecosystems with different stand ages in the arid valley of Minjiang River were studied. The results showed that carbon contents in different organs of C. chengiana were relatively stable, while nitrogen contents were closely related to different organs, and soil organic carbon and nitrogen contents increased with the stand age. Carbon and nitrogen storage in vegetation layer, soil layer, and the whole ecosystem of the plantation increased with the stand age. The values of total carbon storage in the 13-, 11-, 8-, 6- and 4-year-old C. chengiana plantation ecosystems were 190.90, 165.91, 144.57, 119.44, and 113.49 t x hm(-2), and the values of total nitrogen storage were 19.09, 17.97, 13.82, 13.42, and 12.26 t x hm(-2), respectively. Most of carbon and nitrogen were stored in the 0-60 cm soil layer in the plantation ecosystems and occupied 92.8% and 98.8%, respectively, and the amounts of carbon and nitrogen stored in the top 0-20 cm soil layer, accounted for 54.4% and 48.9% of those in the 0-60 cm soil layer, respectively. Difference in distribution of carbon and nitrogen storage was observed in the vegetation layer. The percentage of carbon storage in tree layer (3.7%) were higher than that in understory vegetation (3.5%), while the percentage of nitrogen storage in tree layer (0.5%) was lower than that in understory (0.7%). The carbon and nitrogen storage and distribution patterns in the plantations varied obviously with the stand age, and the plantation ecosystems at these age stages could accumulate organic carbon and nitrogen continuously.

Contribution of Soil Fauna to Foliar Litter-Mass Loss in Winter in an Ecotone between Dry Valley and Montane Forest in the Upper Reaches of the Minjiang River.[Pubmed: 25901894]

Litter decomposition during winter can provide essential nutrients for plant growth in the subsequent growing season, which plays important role in preventing the expansion of dry areas and maintaining the stability of ecotone ecosystems. However, limited information is currently available on the contributions of soil fauna to litter decomposition during winter in such ecosystems. Therefore, a field experiment that included litterbags with two different mesh sizes (0.04 mm and 3 mm) was conducted to investigate the contribution of soil fauna to the loss of foliar litter mass in winter from November 2013 to April 2014 along the upper reaches of the Minjiang River. Two litter types of the dominant species were selected in each ecosystem: cypress (Cupressus chengiana) and oak (Quercus baronii) in ecotone; cypress (Cupressus chengiana) and clovershrub (Campylotropis macrocarpa) in dry valley; and fir (Abies faxoniana) and birch (Betula albosinensis) in montane forest. Over one winter incubation, foliar litter lost 6.0%-16.1%, 11.4%-26.0%, and 6.4%-8.5% of initial mass in the ecotone, dry valley and montane forest, respectively. Soil fauna showed obvious contributions to the loss of foliar litter mass in all of the ecosystems. The highest contribution (48.5%-56.8%) was observed in the ecotone, and the lowest contribution (0.4%-25.8%) was observed in the montane forest. Compared with other winter periods, thawing period exhibited higher soil fauna contributions to litter mass loss in ecotone and dry valley, but both thawing period and freezing period displayed higher soil fauna contributions in montane forest. Statistical analysis demonstrated that the contribution of soil fauna was significantly correlated with temperature and soil moisture during the winter-long incubation. These results suggest that temperature might be the primary control factor in foliar litter decomposition, but more active soil fauna in the ecotone could contribute more in litter decomposition and its related ecological processes in this region.

A new modified sesquiterpene glycoside from Cupressus chengiana.[Pubmed: 24579817]

A new sesquiterpene glycoside, cupressusoside (1), and five known compounds were isolated from the 70% aqueous ethanol extract of the branches and leaves of Cupressus chengiana. Their structures were elucidated by using spectroscopic methods. All the isolates expressed no remarkable cytotoxic activity against colon carcinoma (HCT-8) and breast cancer (MCF-7) cell lines, with IC50>40 mg/mL.

Genetic diversity and conservation implications of four Cupressus species in China as revealed by microsatellite markers.[Pubmed: 24292698]

Understanding the extent and distribution of genetic diversity is crucial for the conservation and management of endangered species. Cupressus chengiana, C. duclouxiana, C. gigantea, and C. funebris are four ecologically and economically important species in China. We investigated their genetic diversity, population structure, and extant effective population size (35 populations, 484 individuals) employing six pairs of nuclear microsatellite markers (selected from 53). Their genetic diversity is moderate among conifers, and genetic differentiation among populations is much lower in C. gigantea than in the other three species; the estimated effective population size was largest for C. chengiana, at 1.70, 2.91, and 3.91 times the estimates for C. duclouxiana, C. funebris, and C. gigantea, respectively. According to Bayesian clustering analysis, the most plausible population subdivision scheme within species is two groups in C. chengiana, three groups in C. duclouxiana, and a single group for both C. funebris and C. gigantea. We propose a conservation strategy for these cypress species.

A study of conservation genetics in Cupressus chengiana, an endangered endemic of China, using ISSR markers.[Pubmed: 16670947]

ISSR markers were used to analyze the genetic diversity and genetic structure of eight natural populations of Cupressus chengiana in China. ISSR analysis using 10 primers was carried out on 92 different samples. At the species level, 136 polymorphic loci were detected. The percentage of polymorphic bands (PPB) was 99%. Genetic diversity (He) was 0.3120, effective number of alleles (Ae) was 1.5236, and Shannon's information index (I) was 0.4740. At the population level, PPB = 48%, Ae = 1.2774, He = 0.1631, and I = 0.2452. Genetic differentiation (Gst) detected by Nei's genetic diversity analysis suggested 48% occurred among populations. The partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (54%) and among populations (46%; P < 0.0003). The average number of individuals exchanged between populations per generation (Nm) was 0.5436. Samples from the same population clustered in the same population-specific cluster, and two groups of Sichuan and Gansu populations were distinguishable. A significantly positive correlation between genetic and geographic distance was detected (r = 0.6701). Human impacts were considered one of the main factors to cause the rarity of C. chengiana, and conservation strategies are suggested based on the genetic characters and field investigation, e.g., protection of wild populations, reestablishment of germplasm bank, and reintroduction of more genetic diversity.