57 Biowissenschaften; Biologie
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Hydrological variability is a key factor in structuring biotic and abiotic processes in river ecosystems and is of particular importance to fish populations. We used 171 hydrological indices (HI) and young-of-the-year (YOY) fish abundances as indicators of reproductive success to compare species' response patterns to high and low flows on short-, intermediate-, and long-term scales. Our study included 13 common fish species in headwater streams of North Rhine-Westphalia, Germany. Generalized linear models using YOY abundances and HI on high- and low-flow patterns explained on average 64 % of the variability. HI calculated from long time series worked better than HI describing short- and intermediate-term high- and low flows. Species' reproductive success response to low flow HI depended on specific ecological traits whereas high flow HI differentially affected species according to their life history strategies. Equilibrium strategists responded negatively to high frequency and magnitude along with late timing of high flow, while periodic and opportunistic species mostly thrived under these conditions. We identified four species traits that mediated these differences between life history strategies. The reproductive success of species with low relative fecundity, large eggs and larvae, and long incubation periods was negatively impacted by the high frequency, high magnitude, and late timing of high flows. Conversely, the reproductive success of species with high relative fecundity, short incubation periods and small eggs and larvae was fostered by strong, frequent, and late high flows. The consideration of the relationship between reproductive success, life history, and fish species traits over several years under a range of flows is a novel step towards the implementation of measures to mitigate negative impacts and enhance conditions for successful fish reproduction.
Science on ecosystems and people to support the Kunming-Montreal Global Biodiversity Framework
(2023)
In December 2022, members of the Convention on Biological Diversity adopted the new Kunming-Montreal Global Biodiversity Framework (GBF) to guide international biodiversity conservation efforts until 2030 in order to be able to live ‘in harmony with nature’ by 2050. This framework addresses the implementation gap left after the Aichi Biodiversity Targets, which were the previous global instrument for mainstreaming biodiversity conservation between 2010 and 2020.
The aim of this editorial is to draw attention to the GBF targets that are most relevant to our readership, with two objectives: First, to suggest how Ecosystems and People may be a venue for emerging research insights in support of the GBF. Second, to highlight examples of recent research in Ecosystems and People that can contribute to enrich, or even challenge, the evidence and development of the GBF Targets.
Species distribution models (SDMs) are key tools in biodiversity and conservation, but assessing their reliability in unsampled locations is difficult, especially where there are sampling biases. We present a spatially-explicit sensitivity analysis for SDMs – SDM profiling – which assesses the leverage that unsampled locations have on the overall model by exploring the interaction between the effect on the variable response curves and the prevalence of the affected environmental conditions. The method adds a ‘pseudo-presence’ and ‘pseudo-absence’ to unsampled locations, re-running the SDM for each, and measuring the difference between the probability surfaces of the original and new SDMs. When the standardised difference values are plotted against each other (a ‘profile plot’), each point's location can be summarized by four leverage measures, calculated as the distances to each corner. We explore several applications: visualization of model certainty; identification of optimal new sampling locations and redundant existing locations; and flagging potentially erroneous occurrence records.
Concerning human and environmental health, safe alternatives to synthetic pesticides are urgently needed. Many of the currently used synthetic pesticides are not authorized for application in organic agriculture. In addition, the developed resistances of various pests against classical pesticides necessitate the urgent demand for efficient and safe products with novel modes of action. Botanical pesticides are assumed to be effective against various crop pests, and they are easily biodegradable and available in high quantities and at a reasonable cost. Many of them may act by diverse yet unexplored mechanisms of action. It is therefore surprising that only few plant species have been developed for commercial usage as biopesticides. This article reviews the status of botanical pesticides, especially in Europe and Mediterranean countries, deepening their active principles and mechanisms of action. Moreover, some constraints and challenges in the development of novel biopesticides are highlighted.
1. Among the many concerns for biodiversity in the Anthropocene, recent reports of flying insect loss are particularly alarming, given their importance as pollinators, pest control agents, and as a food source. Few insect monitoring programmes cover the large spatial scales required to provide more generalizable estimates of insect responses to global change drivers.
2. We ask how climate and surrounding habitat affect flying insect biomass using data from the first year of a new monitoring network at 84 locations across Germany comprising a spatial gradient of land cover types from protected to urban and crop areas.
3. Flying insect biomass increased linearly with temperature across Germany. However, the effect of temperature on flying insect biomass flipped to negative in the hot months of June and July when local temperatures most exceeded long-term averages.
4. Land cover explained little variation in insect biomass, but biomass was lowest in forests. Grasslands, pastures, and orchards harboured the highest insect biomass. The date of peak biomass was primarily driven by surrounding land cover, with grasslands especially having earlier insect biomass phenologies.
5. Standardised, large-scale monitoring provides key insights into the underlying processes of insect decline and is pivotal for the development of climate-adapted strategies to promote insect diversity. In a temperate climate region, we find that the positive effects of temperature on flying insect biomass diminish in a German summer at locations where temperatures most exceeded long-term averages. Our results highlight the importance of local adaptation in climate change-driven impacts on insect communities.
Ephemeroptera, Plecoptera and Trichoptera are three orders of freshwater macroinvertebrates with a short terrestrial adult life-stage that they use to disperse by flying upstream. This aerial dispersal can be assisted by native riparian forest, but regional variation has not yet been empirically tested. In this study we compared the EPT community of 153 sampling sites located in freshwater streams in four European regions (Central Plains, Central Highlands, Alps, Iberia). In each site, we assessed the EPT community dispersal ability using the Species Flying Propensity index. We also calculated the native deciduous forest cover in the riparian buffer and several environmental stressors such as saprobic pollution or catchment anthropization. Finally, we tested which of these parameters have a significant effect on the EPT community. In the Central Highlands and in Iberia, the share of weak dispersers increased with native deciduous forest cover, indicating a positive effect on dispersal of EPTs. In the Central Plains and the Alps, no such effect was found. We conclude that the effect of native deciduous forest depends on regional landscape characteristics and the regional species pool, but considering the dispersal of the regional EPT communities is needed to create effective river management policies.
Global change effects on biodiversity and human wellbeing call for improved long-term environmental data as a basis for science, policy and decision making, including increased interoperability, multifunctionality, and harmonization. Based on the example of two global initiatives, the International Long-Term Ecological Research (ILTER) network and the Group on Earth Observations Biodiversity Observation Network (GEO BON), we propose merging the frameworks behind these initiatives, namely ecosystem integrity and essential biodiversity variables, to serve as an improved guideline for future site-based long-term research and monitoring in terrestrial, freshwater and coastal ecosystems. We derive a list of specific recommendations of what and how to measure at a monitoring site and call for an integration of sites into co-located site networks across individual monitoring initiatives, and centered on ecosystems. This facilitates the generation of linked comprehensive ecosystem monitoring data, supports synergies in the use of costly infrastructures, fosters cross-initiative research and provides a template for collaboration beyond the ILTER and GEO BON communities.
Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss1. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity2. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity.