57 Biowissenschaften; Biologie
Filtern
Dokumenttyp
Sprache
- Englisch (21)
Volltext vorhanden
- ja (21)
Gehört zur Bibliographie
- nein (21)
Schlagworte
- Biodiversität (9)
- Insekten (6)
- Biomonitoring (4)
- Biomasse (3)
- Europa (3)
- Klimaänderung (3)
- Malaise trap (3)
- Wirbellose (3)
- biodiversity (3)
- Aquatisches Ökosystem (2)
Widespread insect losses are a critical global problem. Mitigating this problem requires identifying the principal drivers across different taxa and determining which insects are covered by protected areas. However, doing so is hindered by missing information on most species owing to extremely high insect diversity and difficulties in morphological identification. To address this knowledge gap, we used one of the most comprehensive insect DNA metabarcoding data sets assembled (encompassing 31,846 flying insect species) in which data were collected from a network of 75 Malaise traps distributed across Germany. Collection sites encompass gradients of land cover, weather, and climate, along with differences in site protection status, which allowed us to gain broader insights into how insects respond to these factors. We examined changes in total insect biomass, species richness, temporal turnover, and shifts in the composition of taxa, key functional groups (pollinators, threatened species, and invasive species), and feeding traits. Lower insect biomass generally equated to lower richness of all insects and higher temporal turnover, suggesting that biomass loss translates to biodiversity loss and less stable communities. Spatial variability in insect biomass and composition was primarily driven by land cover, rather than weather or climate change. As vegetation and land-cover heterogeneity increased, insect biomass increased by 50% in 2019 and 56% in 2020 and total species richness by 58% and 33%, respectively. Similarly, areas with low-vegetation habitats exhibited the highest richness of key taxa, including pollinators and threatened species, and the widest variety of feeding traits. However, these habitats tended to be less protected despite their higher diversity. Our results highlight the value of heterogeneous low vegetation for promoting overall insect biomass and diversity and that better protection of insects requires improved protection and management of unforested areas, where many biodiversity hotspots and key taxa occur.
Increasing evidence for insect biodiversity decline requires an identification of the causes but also an improved understanding of the limitations of the various underlying sampling methods. Trap comparisons foster comparability of larger-scale biodiversity studies by providing a deeper understanding of the variations in species abundances and trait compositions due to variations in trap characteristics. In our study, we compared five Malaise trap types on their catchability of butterfly species and noctuid moths and examined for the butterflies how this can be related to traits. We showed marked differences in species and trait occurrence in the samples of the different trap types which seemed to be influenced by roof colour (white, black) and trap shape (Townes trap: high, wide roof, Bartak trap: low, narrow roof). We found most butterfly species and most butterfly biomass in the white-roofed Townes trap. All butterfly traits were represented with most individuals in this trap. Compared with its black counterpart, it showed increased catches for pale butterflies and forest species. We found that dark-roofed traps captured fewer butterfly species and had a lower butterfly biomass. Townes traps captured more butterflies with larger wingspans, egg-laying locations higher above ground, and tree feeding behaviour compared to Bartak traps. Depending on the season and habitat, the differences in species capture may affect overall insect biomass.
Mitigating ongoing losses of insects and their key functions (e.g. pollination) requires tracking large-scale and long-term community changes. However, doing so has been hindered by the high diversity of insect species that requires prohibitively high investments of time, funding and taxonomic expertise when addressed with conventional tools. Here, we show that these concerns can be addressed through a comprehensive, scalable and cost-efficient DNA metabarcoding workflow. We use 1815 samples from 75 Malaise traps across Germany from 2019 and 2020 to demonstrate how metabarcoding can be incorporated into large-scale insect monitoring networks for less than 50 € per sample, including supplies, labour and maintenance. We validated the detected species using two publicly available databases (GBOL and GBIF) and the judgement of taxonomic experts. With an average of 1.4 M sequence reads per sample we uncovered 10,803 validated insect species, of which 83.9% were represented by a single Operational Taxonomic Unit (OTU). We estimated another 21,043 plausible species, which we argue either lack a reference barcode or are undescribed. The total of 31,846 species is similar to the number of insect species known for Germany (~35,500). Because Malaise traps capture only a subset of insects, our approach identified many species likely unknown from Germany or new to science. Our reproducible workflow (~80% OTU-similarity among years) provides a blueprint for large-scale biodiversity monitoring of insects and other biodiversity components in near real time.
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.
1. Woody riparian vegetation (WRV) benefits benthic macroinvertebrates in running waters. However, while some functions are provided by WRV irrespective of surrounding and catchment land use, others are context-specific. In recent large-scale studies, effects of WRV on macroinvertebrates were therefore small compared to catchment land use, raising the question about the relevance of WRV for restoration.
2. Model-based recursive partitioning was used to identify context-dependent effects of WRV on the macroinvertebrates' ecological status in small (catchment area 10–100 km2) lowland (n = 361) and mountain (n = 748) streams. WRV cover was quantified from orthophotos along the near (500 m) and far (5000 m) upstream river network and used to predict the site's ecological status. Agricultural, urban and woodland cover at the local and catchment scales along with hydromorphology were considered as partitioning variables.
3. In rural agricultural landscapes, the effect of WRV on the ecological status was large, indicating that establishing near-upstream WRV can improve the ecological status by as much as two of the five classes according to the EU Water Framework Directive.
4. Even in urban landscapes, effects of far-upstream WRV were large if catchments had a moderate share of agricultural land use in addition. The beneficial effects of WRV were only limited in purely urban catchments or in a multiple stressor context.
5. Synthesis and applications. While woody riparian vegetation (WRV) can even improve the ecological status in urban settings, it is especially relevant for river management in rural agricultural catchments, where developing WRV potentially are effective measures to achieve good ecological status.
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.
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.
Diadromous fish have exhibited a dramatic decline since the end of the 20th century. The allis shad (Alosa alosa) population in the Gironde-Garonne-Dordogne (GGD) system, once considered as a reference in Europe, remains low despite a fishing ban in 2008. One hypothesis to explain this decline is that the downstream migration and growth dynamics of young stages have changed due to environmental modifications in the rivers and estuary. We retrospectively analysed juvenile growth and migration patterns using otoliths from adults caught in the GGD system 30 years apart during their spawning migration, in 1987 and 2016. We coupled otolith daily growth increments and laser ablation inductively-coupled plasma mass spectrometry measurements of Sr:Ca, Ba:Ca, and Mn:Ca ratios along the longest growth axis from hatching to an age of 100 days (i.e., during the juvenile stage). A back-calculation allowed us to estimate the size of juveniles at the entrance into the brackish estuary. Based on the geochemistry data, we distinguished four different zones that juveniles encountered during their downstream migration: freshwater, fluvial estuary, brackish estuary, and lower estuary. We identified three migration patterns during the first 100 days of their life: (a) Individuals that reached the lower estuary zone, (b) individuals that reached the brackish estuary zone, and (c) individuals that reached the fluvial estuary zone. On average, juveniles from the 1987 subsample stayed slightly longer in freshwater than juveniles from the 2016 subsample. In addition, juveniles from the 2016 subsample entered the brackish estuary at a smaller size. This result suggests that juveniles from the 2016 subsample might have encountered more difficult conditions during their downstream migration, which we attribute to a longer exposure to the turbid maximum zone. This assumption is supported by the microchemical analyses of the otoliths, which suggests based on wider Mn:Ca peaks that juveniles in 2010s experienced a longer period of physiological stress during their downstream migration than juveniles in 1980s. Finally, juveniles from the 2016 subsample took longer than 100 days to exit the lower estuary than we would have expected from previous studies. Adding a new marker (i.e., Ba:Ca) helped us refine the interpretation of the downstream migration for each individual.
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.
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
