An Inventory and Seasonal Changes in the Recent Benthic Flora of Coral Reefs of Wuzhizhou Island,Haitang Bay,South China Sea (China)

Russian Journal of Marine Biology - Intensive algal sampling was conducted from 2017 to 2019 in coastal waters of Wuzhizhou Island (South China Sea, China). In total, 183 species of marine...     

Traits mediate drought effects on wood carbon fluxes

CO₂ fluxes from wood decomposition represent an important source of carbon from forest ecosystems to the atmosphere, which are determined by both wood traits and climate influencing the metabolic rates of decomposers. Previous studies have quantified the effects of moisture and temperature on wood decomposition, but these effects were not separated from the potential influence of wood traits. Indeed, it is not well understood how traits and climate interact to influence wood CO₂ fluxes. Here, we examined the responses of CO₂ fluxes from dead wood with different traits (angiosperm and gymnosperm) to 0%, 35%, and 70% rainfall reduction across seasonal temperature gradients. Our results showed that drought significantly decreased wood CO₂ fluxes, but its effects varied with both taxonomical group and drought intensity. Drought‐induced reduction in wood CO₂ fluxes was larger in angiosperms than gymnosperms for the 35% rainfall reduction treatment, but there was no significant difference between these groups for the 70% reduction treatment. This is because wood nitrogen density and carbon quality were significantly higher in angiosperms than gymnosperms, yielding a higher moisture sensitivity of wood decomposition. These findings were demonstrated by a significant positive interaction effect between wood nitrogen and moisture on CO₂ fluxes in a structural equation model. Additionally, we ascertained that a constant temperature sensitivity of CO₂ fluxes was independent of wood traits and consistent with previous estimates for extracellular enzyme kinetics. Our results highlight the key role of wood traits in regulating drought responses of wood carbon fluxes. Given that both climate and forest management might extensively modify taxonomic compositions in the future, it is critical for carbon cycle models to account for such interactions between wood traits and climate in driving dynamics of wood decomposition.     

Transmission competence of a new mesonivirus,Yichang virus,in mosquitoes and its interference with representative flaviviruses

Advances in technology have greatly stimulated the understanding of insect-specific viruses (ISVs). Unfortunately, most of these findings are based on sequencing technology, and laboratory data are scarce on the transmission dynamics of ISVs in nature and the potential effects of these viruses on arboviruses. Mesonivirus is a class of ISVs with a wide geographical distribution. Recently, our laboratory reported the isolation of a novel strain of mesonivirus, Yichang virus (YCV), from Culex mosquitoes, China. In this study, the experimental infection of YCV by the oral route for adult and larvae mosquitoes, and the vertical transmission has been conducted, which suggests that YCV could adopt a mixed-mode transmission. Controlled experiments showed that the infectivity of YCV depends on the mosquito species, virus dose, and infection route. The proliferation curve and tissue distribution of YCV in Cx. quinquefasciatus and Ae. albopictus showed that YCV is more susceptible to Ae. albopictus and is located in the midgut. Furthermore, we also assessed the interference of YCV with flaviviruses both in vitro and in vivo. YCV significantly inhibited the proliferation of DENV-2 and ZIKV, in cell culture, and reduced transmission rate of DENV-2 in Ae. albopictus. Our work provides insights into the transmission of ISVs in different mosquito species during ontogeny and their potential ability to interact with mosquito-borne viruses.     

大渡河中游干暖河谷区生境对植物群落分布格局和多样性的影响

大渡河中游干暖河谷区滑坡和泥石流灾害频发, 对该区域坡面植物群落的研究有助于揭示植被演替的方向, 为坡面植被生态恢复提供基本依据。本研究沿大渡河中游河谷区每隔约5 km设置典型样地, 调查了植被的物种组成和分布以及样地的地形、土壤等10个生境因子, 探讨河谷区植被的连续性变化, 并通过多元回归树(multivariate regression trees, MRT)、多样性指数和典范对应分析(canonical correspondence analysis, CCA)等方法对植物群落进行分类、比较和排序。结果表明: 大渡河中游干暖河谷植被以土壤碳含量、pH值和C : N等3个因子为节点, 可划分为多花胡枝子(Lespedeza floribunda)-荩草(Arthraxon hispidus)-香薷(Elsholtzia ciliate)(群落A)、地果(Ficus tikoua)-车桑子(Dodonaea viscosa)-川滇薹草(Carex schneideri)(群落B)、云南松(Pinus yunnanensis)-栓皮栎(Quercus variabilis)(群落C)和荩草-扭黄茅(Heteropogon contortus)(群落D)等4种群落。该区域以灌木和草本为主要植被类型(群落A、B、C), 间或有裸地分布, 易成为泥石流灾害产生的物源区; 以多花胡枝子为主的灌草群落A的物种丰富度、优势度与多样性表现一致, 均高于以乔木和草本为主的群落C和D, 但物种多样性优势并不显著, 灌草群落分布广而结构单一, 外来物种占比为8.33%, 是生态系统脆弱和不稳定的表现。多元回归树和典范对应分析结果表明, pH值、C : N、坡向和土壤容重等4个因子对植物群落组成和分布影响最大, 且土壤因子的影响大于地形因子。