Fine‐scale genetic diversity and landscape‐scale genetic structuring in three foundational bulrush species: implications for wetland revegetation

The appropriate sourcing of seeds for restoration is critical for establishing foundational plant species that support ecosystem functions and services. Genetic analyses of such species can yield insights into patterns of genetic diversity and structuring to inform seed collections. Here we document, for three foundational bulrush species, distinct genetic patterns to guide restoration of wetlands along the iconic Great Salt Lake, the largest lake in western North America. Specifically, Schoenoplectus acutus and Schoenoplectus americanus had moderate levels of site‐scale genet richness and relatively low genet richness levels within 1‐m² plots. These patterns contrast with Bolboschoenus maritimus, which had higher levels of site‐ and plot‐level genet richness, and has therefore likely experienced more recent seedling establishment. At the landscape scale, we found some evidence for genetic isolation of individuals at more remote sites (namely Fish Springs National Wildlife Refuge in the West Desert of Utah), but all species are relatively well dispersed over hundreds of kilometers, a pattern most likely to occur via avian dispersal. In our mechanistic dispersal assessment, we found abundant bulrush seeds present in waterfowl gizzards and those seeds germinated readily despite (or because of) partial digestion. Migratory waterfowl likely facilitate the broad dispersal of all species and may aid in bulrush establishment by breaking seed dormancy. These findings suggest that seeds for restoration should be collected within and among seed source sites to ensure a diverse restoration seed lot that does not disrupt gene flow patterns.     

Lack of prey switching and strong preference for mosquito prey by a temporary pond specialist predator

1. The strengths of trophic interactions within ecosystems can be mediated by complex mechanisms that require elucidation if researchers are to understand and predict population- and community-level stabilities. Where multiple prey types co-occur, prey switching (i.e. frequency-dependent predation) by predators may facilitate low-density prey refuge effects which promote coexistence. On the other hand, lack of switching and strong preferences by predators can strongly suppress prey populations, which is especially important considering vector species such as mosquitoes. 2. The present study quantifies prey switching and preference patterns of the temporary pond specialist copepod Lovenula raynerae towards larvae of the medically important Culex pipiens mosquito complex in the presence of different proportions of alternative Daphnia pulex prey. Further, it examines whether prey switching and preferences are contingent on the sex of the predator. 3. Lovenula raynerae exhibited a lack of prey switching and strong preference for larval mosquito prey overall, irrespective of predator sex. Also, when larval mosquitoes were available in higher proportions over daphniids, the strength of this positive selectivity increased. There was very little low-density refuge for mosquitoes where they were rare. 4. Lack of prey switching and strong preferences towards mosquitoes by predatory paradiaptomid copepods may enhance population-level regulation of disease vector mosquitoes that exploit temporary pond-style habitats. Accordingly, the conservation and promotion of these predators might enable better management of medically important species across landscapes.     

Conflicting demands on wetland ecosystem services: nutrient retention,biodiversity or both?

1. Wetland ecosystems may, besides having considerable economical value, increase landscape biodiversity and function as traps for nutrients from land to freshwater‐ and marine systems. As a result of these features, wetlands are nowadays often protected and restored, and many countries have even initiated wetland construction programmes. 2. In the present study, we aim at increasing the knowledge on how to improve the design of a wetland with respect to both biodiversity and nutrient retention, by analysing physical, chemical and biological features of a large set of constructed wetlands. 3. Our results show that a combination of the wetland features, namely shallow depth, large surface area and high shoreline complexity are likely to provide a high biodiversity of birds, benthic invertebrates and macrophytes and to have high nitrogen retention, whereas a small, deep wetland is likely to be more efficient in phosphorus retention, but less valuable in terms of biodiversity. 4. Hence, among the features used to design new wetlands, area, depth and shoreline complexity have fundamental, and sometimes conflicting, effects on nutrient retention and biodiversity. This means that there are, within limits, possibilities to direct the ecosystem function of a specific wetland in desired directions.     

Effect of early dry season induced by the Three Gorges Dam on the soil microbial biomass and bacterial community structure in the Dongting Lake wetland

In this study, we used the soil microbial biomass (SMB) and the bacterial community structure as indicators to determine the potential ecological responses of the Dongting Lake wetland (China) to the early dry season that has been induced by the Three Gorges Dam (TGD), the largest hydroelectric project in the world. We measured the soil properties, SMB and bacterial community structure for samples E0, E20 and E40 (for which the dry season arrived early by 0, 20 and 40 days, respectively). The results indicated a significant increase in SMB as the dry season occurred increasingly earlier. The microbial biomass carbon (MBC) was used as a representative for the SMB and increased for the samples in the following order: E0 < E20 < E40. The bacterial 16S rDNA gene copy number changed similarly to the MBC. Significant changes were also observed in the soil bacterial community structure. The bacterial community structure of E40 was more diverse than that of E20, which was similar to that of E0. The relationship between the bacterial community composition and the soil properties was evaluated by redundancy analysis (RDA). The results indicated that the lead time of the dry season was the controlling influence on the soil bacterial community structure.     

高寒湿地土壤微生物区系组成对氮添加的响应

土壤微生物是土壤养分循环的关键驱动者,对土壤环境变化感应明显,氮是陆地生态系统的限制元素之一,其改变可能会给生态系统物种多样性造成一定影响.为了解高寒湿地土壤微生物组成对氮添加的响应,以青海湖流域高寒湿地为研究对象,通过(0 g·m-2、0.5 g·m-2、1 g·m-2、1.5 g·m-2、2 g·m-2、2.5 g...     

青岛市湿地生态网络评价与构建

在快速城市化背景下,城市社会经济发展与空间扩张不可避免,往往造成栖息地数量、面积、质量锐减、栖息地之间联系破碎等后果。此外,全球气候变化也加剧了栖息地恶化过程。生态网络通过保护恢复重点栖息地及构建栖息地之间物质、信息及能量传播的连接廊道,在整体上维持生态系统的动态平衡。青岛市位于东部沿海经济发达地区,地处海洋与陆地生态系统的交汇处,生态环境极为脆弱,易遭受外力破坏,且难以恢复。选取青岛地区湿地作为研究对象,在RS,GIS技术支持下,基于最小成本路径法构建青岛市湿地生态网络,并利用关联长度指数、介数指数对网络的整体结构及斑块重要程度进行评价。结果表明,不同路径成本阈值水平下,网络的连通性有很大差别;核心斑块中,胶州湾湿地、大沽河等具有较高重要程度;歇脚石斑块中,重要程度较高的斑块位于以胶州湾湿地为中心,以胶莱河、潍河河口,白马河、潮河河口及丁字湾为端点的连线上。在青岛市及周边地区划定"一心、二轴、一环"的湿地生态网络控制框架的策略,为青岛市湿地生态系统保护与城市发展空间选择提供科学方法与量化依据。