Tree species richness enhances stand productivity while stand structure can have opposite effects, based on forest inventory data from Germany and the United States of America

Background： in recent studies, mixed forests were found to be more productive than monocultures with everything else remaining the same. Methods： To find out if this productivity is caused by tree species richness, by a more heterogeneous stand structure or both, we analyzed the effects of forest structure and tree species richness on stand productivity, based on inventory data of temperate forests in the United States of America and Germany. Results： Having accounted for effects such as tree size and stand density, we found that： （I） tree species richness increased stand productivity in both countries while the effect of tree size heterogeneity on productivity was negative in Germany but positive in the USA; （11） productivity was highest at sites with an intermediate amount of precipitation; and （111） growth limitations due water scarcity or low temperature may enhance structural heterogeneity. Conclusions： In the context of forest ecosystem goods and services, as well as future sustainable forest resource management, the associated implications would be：

Analysis of sex pheromone production and field trapping of the Asian corn borer(Ostrinia furnacalis Guenée)in Xinjiang,China

Identifying the sex pheromone systems of local pest populations facilitates their management,especially for moth species that show significant geographic variation in sex pheromone communication.We investigated the pheromone production and behavioral responses of the Asian corn borer(Ostrinia furnacalis Guenée;ACB)in Xinjiang,China.The ACB produces three compounds:(Z)-12-tetradecenyl acetate(Z12-14:Ac)and(E)-12-tetradecenyl acetate(E12-14:Ac)which are two sex pheromone compounds,and n-tetradecyl acetate(14:Ac)which has variable roles in mediating behavioral responses.The ratios of these three compounds produced in female gland are geographically distinct among different populations.Quantitative analysis of pheromone production showed that the proportions of Z12-14:Ac in the E/Z isomers(i.e.,Z and E12-14:Ac)and the proportions of 14:Ac in the ternary blend respectively averaged 60.46%(SD=5.26)and 25.00%(SD=7.37),with their probabilities normally or near-normally distributed.Trapping experiments in a cornfield indicated that deploying the E/Z isomers and the three compounds in rubber septa close to their gland ratios yielded the most captured males,while other ratios that deviated from the gland ratios showed reduced field captures.The ternary blend was significantly more attractive to males than the E/Z isomers in the field,indicating a functional role of 14:Ac as the third pheromone component used by the local population.Additionally,the dose-response test demonstrated that the application of the three compounds at dosages between 200 and 350μg attracted significantly more males compared to other dosages.Therefore,the characterization of this local ACB pheromone system provides additional information about its geographic variation and serves as a basis for optimizing the pheromone-mediated control of this pest in Xinjiang.

Large-scale forest inventories of the United States and China reveal positive effects of biodiversity on productivity

Background： With the loss of species worldwide due to anthropogenic factors, especially in forested ecosystems, it has become more urgent than ever to understand the biodiversity-ecosystem functioning relationship （BEFR）. BEFR research in forested ecosystems is very limited and thus studies that incorporate greater geographic coverage and structural complexity are needed. Methods： We compiled ground-measured data from approx, one half million forest inventory sample plots across the contiguous United States, Alaska, and northeastern China to map tree species richness, forest stocking, and productivity at a continental scale. Based on these data, we investigated the relationship between forest productivity and tree species diversity, using a multiple regression analysis and a non-parametric approach to account for spatial autocorrelation. Results： In general, forests in the eastern United States consisted of more tree species than any other regions in the country. The highest forest stocking values over the entire study area were concentrated in the western United States and Central Appalachia. Overall, 96.4 % of sample plots （477,281） showed a significant positive effect of species richness on site productivity, and only 3.6 % （17,349） had an insignificant or negative effect. Conclusions： The large number of ground-measured plots, as well as the magnitude of geographic scale, rendered overwhelming evidence in support of a positive BEFR. This empirical evidence provides insights to forest management and biological conservation across different types of forested ecosystems. Forest timber productivity may be impaired by the loss of species in forests, and biological conservation, due to its potential benefits on maintaining species richness and productivity, can have profound impacts on the functioning and services of forested ecosystems.

Simultaneous Detection of <i>Colletotrichum acutatum</i>and <i>C. gloeosporioides</i>from Quiescently Infected Strawberry Foliage by Real-Time PCR Based on High Resolution Melt Curve Analysis

Anthracnose of strawberry, caused primarily by the fungal pathogens belonging to Colletotrichum acutatum species complex (CASC) and C. gloeosporioides species complex (CGSC) is an economically important disease in the Southeast United States. Quiescently infected (QI) planting stock is one of the most important sources of inoculum in the fruiting field that can only be reliably detected by highly sensitive real time quantitative PCR (q-PCR) assay. In this study, a q-PCR assay was developed and optimized that can discriminate anthracnose fruit rot (AFR) and anthracnose crown rot (ACR) causing species based on the difference in post PCR melting temperatures of amplicons. Controlled environment grown plants artificially inoculated with different levels of CASC and CGSC showed a significant (P 0.001) correlation with levels of quantification expressed by Ct values in q-PCR from petioles and leaf blades. The leaf blade was a significantly larger reservoir of QI than that of the petiole. Both TaqMan and SYBR Green assay showed similar sensitivity and specificity. Detection of QI on leaves at young middle and older stages from inoculation with same number of conidia indicated that middle aged leaves were the best for assessing QI. Quantification of QI from middle aged leaf samples from a strawberry fruiting field that has been planted with pre-inoculated plants at both ends of rows and let inoculum spread showed higher sensitivity and precision by q-PCR compared to that of a traditional paraquat assay. The assay developed and validated in this study offers a new tool for evaluating planting stocks for QI to make decision on preventative control for strawberry anthracnose.

Genetic assessment of inbred chicken lines indicates genomic signatures of resistance to Marek's disease

Background: Marek’s disease(MD) is a highly contagious pathogenic and oncogenic disease primarily affecting chickens. However, the mechanisms of genetic resistance for MD are complex and not fully understood. MD-resistant line 63and MD-susceptible line 72are two highly inbred progenitor lines of White Leghorn. Recombinant Congenic Strains(RCS) were developed from these two lines, which show varied susceptibility to MD.Results: We investigated genetic structure and genomic signatures across the genome, including the line 63and line72, six RCSs, and two reciprocally crossed flocks between the lines 63and 72(F1 63× 72and F1 72× 63) using Affymetrix~? Axiom~? HD 600 K genotyping array. We observed 18 chickens from RCS lines were specifically clustered into resistance sub-groups distributed around line 63. Additionally, homozygosity analysis was employed to explore potential genetic components related to MD resistance, while runs of homozygosity(ROH) are regions of the genome where the identical haplotypes are inherited from each parent. We found several genes including SIK, SOX1, LIG4, SIK1 and TNFSF13B were contained in ROH region identified in resistant group(line 63and RCS), and these genes have been reported that are contribute to immunology and survival. Based on FSTbased population differential analysis, we also identified important genes related to cell death and anti-apoptosis, including AKT1, API5, CDH13, CFDP and USP15,which could be involved in divergent selection during inbreeding process.Conclusions: Our findings offer valuable insights for understanding the genetic mechanism of resistance to MD and the identified genes could be considered as candidate biomarkers in further evaluation.

Measuring benefits of rural-to-urban water transfer:a case study from Puyang River basin,China

Agriculture-to-urban water transfer is currently an important measure to meet the increasing water demand resulting from rapid industrialization and urbanization in China.Measuring benefits of agriculture-to-urban water transfer is critical to assess water transfer proposals,and it can also provide reliable basis for redistributing the benefits of agriculture-to-urban water transfer.This paper has developed a comprehensive framework in which production function approach is applied to quantify the value of water use in agricultural and industrial sectors,and contingent valuation method is employed to investigate the value of water use in municipal consumption and ecological environment.A case study from Zhuji City in China verified the feasibility and validity of the method proposed in the paper.Results indicate that the agriculture-to-urban water transfer increases the water value created by improving allocation efficiency of water use in different sectors.The benefits of agriculture-to-urban water transfer mainly originate from the fact that the economic value in industrial water use is higher than in the other sectors’water use.Meanwhile,the urban residents have a stronger desire to improve the water eco-environment which leads to higher water value in urban area.

Functional Equivalence of Created Wetland Water Quality: A Comparison of Amphibian Metamorphic Success

Wetlands are often created through wetland mitigation to replace lost natural wetlands, but further evaluation is needed to determine the ability of a created wetland to replace lost wetland functions, especially providing wildlife habitat. We used a mesocosm design to compare the water quality between three created wetlands and three natural wetlands in West Virginia, USA and to evaluate how the water quality from the two wetland types were able to support metamorphosis in larval spring peepers (Pseudacris crucifer) and wood frogs (Lithobates sylvaticus) across two years (2014-2015). Responses in metamorphosis rates differed between species and between years. Spring peepers displayed similar metamorphosis rates in the created and natural wetlands in both years of the study. Wood frogs displayed similar metamorphosis rates in created and natural wetlands in 2015, but in 2014 wood frogs reached metamorphosis in less time and at a larger body size in the natural wetlands, suggesting that the wood frogs that developed in the natural wetlands may have higher fitness than those that developed in the created wetlands. Water quality was largely similar between created and natural wetlands, although dissolved oxygen, conductivity, and pH varied between mesocosms and wetlands. Our study suggests that created wetlands may be providing partial mitigation in terms of water quality for amphibian development. We recommend that future monitoring of created wetlands include measures of juvenile amphibian recruitment as well as additional habitat variables to better determine the ability of created wetlands to function as amphibian habitat.

Effect of Lipopolysaccharide-Induced Immune Responses on Pregnancy Loss in Ewes

An acute phase response induced by Gram-negative bacteria can reduce pregnancy rate. Early pregnant ewes were used to monitor effects of lipopolysaccharide (LPS), an endotoxin in the outer cell membrane of Gram-negative bacteria, on acute phase/innate immunity response. In Exp. 1, mixed breed ewes were assigned to receive either LPS or LPS and flunixin meglumine, an inhibitor of prostaglandin synthetase, intravenously on day 5 after mating. In Exp. 2, mixed breed ewes were assigned to receive an intravenous injection on day 5 after mating of either saline, LPS, recombinant human tumor necrosis factor (TNF)-α or LPS after pretreatment with dexamethasone. Pregnancy was diagnosed ultrasonographically on d 25, and live births were recorded at parturition. Challenge with LPS induced acute phase responses (fever, mucosal responses, lethargy and increased serum TNF, haptoglobin and?serum amyloid A) and decreased pregnancy rates. Predictably, flunixin meglumine attenuated fever but did not increase pregnancy rate in LPS-treated ewes. Similarly, exogenous TNF alone induced mucosal and serum amyloid A responses but did not affect pregnancy. Pre-treatment with dexamethasone blocked fever and mucosal and lethargic responses and attenuated increases in TNF and haptoglobin but did not ameliorate LPS-induced pregnancy loss. In summary, acute challenge with LPS mimics bacterial-induced pregnancy losses in early pregnant ewes. Although pretreatment with dexamethasone decreased clinical signs and some innate immune responses, neither it nor flunixin meglumine prevented LPS-induced pregnancy loss. That exogenous TNF alone did not promote pregnancy loss indicates that other cytokines also contribute to LPS-induced embryonic loss.

国内外奥运旅游研究进展综述

自公元前776年举办第一届古代奥运会以来,旅游与奥运会便形影相随。随着现代人类休闲时间的增多与经济承受力的增强,作为大型事件的奥运会吸引了越来越多的旅游者观光游览,同时也受到旅游学术界越来越多的关注。本文以奥运旅游的起源、奥运旅游的定义与特点出发,从奥运旅游研究历史、吸引物研究、市场特征研究、经济社会影响研究等多方面对国内外奥运旅游研究进行了总结。

Periconceptional growth hormone treatment alters early uterine environment

We have shown that an injection of sustained release growth hormone (GH), given just prior to breeding, results in lambs that are 25% heavier at birth, with an altered body composition as evidenced by an increased abdominal girth, but no difference in crown rump length. The mechanisms by which these differences occur from a single periconceptional injection are not yet known. Therefore, the objective of this experiment was to determine the effect of an injection of GH given prior to breeding on the composition of the uterine luminal environment and the embryo at the time of blastocyst. Ewes were synchronized with two injections of prostaglandin F2α given eight days apart. On the day of the second injection, ewes were randomly assigned to be given an injection of sustained release GH or remain as controls and penned with a ram. On day 6.5 following breeding embryos were collected. Prior to surgery a jugular blood sample was taken to determine plasma progesterone and urea concentration. The uterine content of urea, prostaglandin F2α, prostaglandin E2, transforming growth factor β-1 (TGF β), and nitric oxide metabolites were measured. Collected embryos were differentially stained to calculate a trophectoderm to inner cell mass ratio. The concentration of progesterone in maternal plasma was greater in the treated group compare to controls, but blood urea nitrogen was not different between groups. The uterine content of urea in the GH group was lower than that of the control group. There was a trend for TGF β to be increased in the GH treated group compared to control (P = 0.07). There was no difference (P > 0.05) in the total uterine content prostaglandin F2α, prostaglandin E2 or nitric oxide metabolites. The trophectoderm to inner cell mass ratio was not different between treatment groups. Thus, we suggest that the observed difference in fetal development following periconceptional growth hormone administration just prior to breeding may be the result of an alteration in the uterine luminal environment, which may alter the cellular program of the conceptus and later development beyond the embryonic stage.

Understorey plant community assemblage of Australian Eucalyptus woodlands under elevated CO_(2)is modulated by water and phosphorus availability

Aims Given the key functional role of understorey plant communities and the substantial extent of forest cover at the global scale,investigating understorey community responses to elevated CO_(2)(eCO_(2))concentrations,and the role of soil resources in these responses,is important for understanding the ecosystem-level consequences of rising CO_(2)concentrations for forest ecosystems.Here,we evaluated how experimentally manipulating the availabilities of the two most limiting resources in an extremely phosphorus-limited eucalypt woodland in eastern Australia(i.e.water and phosphorus)can modulate the response of the understorey community to eCO_(2)in terms of germination,phenology,cover,community composition and leaf traits.Methods We collected soil containing native soil seed bank to grow experimental understorey plant communities under glasshouse conditions.Important Findings Phosphorus addition increased total plant cover,particularly during the first 4 weeks of growth and under high water conditions,a response driven by the graminoid component of the plant community.However,the treatment differences diminished as the experiment progressed,with all treatments converging at〜80%lant cover after〜11 weeks.In contrast,plant cover was not affected by eCO_(2).Multivariate analyses reflected temporal changes in the composition of plant communities,from pots where bare soil was dominant to high-cover pots dominated by a diverse community.However,both phosphorus addition and the interaction between water availability and CO_(2)affected the temporal trajectory of the plant community during the experiment.eCO_(2)also increased community-level specific leaf area,suggesting that functional adaptation of plant communities to CO_(2)may precede the onset of compositional responses.Given that the response of our seed bank-derived understorey community to CO_(2)developed over time and was mediated by interactions with phosphorus and water availability,our results suggest a limited role of eCO_(2)in shaping plant communities in water-limited systems,particularly where low soil nutrient availability constrains productivity responses.