Happe A.-K., Alins G., Blüthgen N., Boreux V., Bosch J., García D., Hambäck P.A., Klein A.-M., Martínez-Sastre R., Miñarro M., Müller A.-K., Porcel M., Rodrigo A., Roquer-Beni L., Samnegård U., Tasin M., Mody K. (2019) Predatory arthropods in apple orchards across Europe: Responses to agricultural management, adjacent habitat, landscape composition and country. Agriculture, Ecosystems and Environment. 273: 141-150.LinkDoi: 10.1016/j.agee.2018.12.012
Local agri-environmental schemes, including hedgerows, flowering strips, organic management, and a landscape rich in semi-natural habitat patches, are assumed to enhance the presence of beneficial arthropods and their contribution to biological control in fruit crops. We studied the influence of local factors (orchard management and adjacent habitats) and of landscape composition on the abundance and community composition of predatory arthropods in apple orchards in three European countries. To elucidate how local and landscape factors influence natural enemy effectiveness in apple production systems, we calculated community energy use as a proxy for the communities’ predation potential based on biomass and metabolic rates of predatory arthropods. Predator communities were assessed by standardised beating samples taken from apple trees in 86 orchards in Germany, Spain and Sweden. Orchard management included integrated production (IP; i.e. the reduced and targeted application of synthetic agrochemicals), and organic management practices in all three countries. Predator communities differed between management types and countries. Several groups, including beetles (Coleoptera), predatory bugs (Heteroptera), flies (Diptera) and spiders (Araneae) benefited from organic management depending on country. Woody habitat and IP supported harvestmen (Opiliones). In both IP and organic orchards we detected aversive influences of a high-quality surrounding landscape on some predator groups: for example, high covers of woody habitat reduced earwig abundances in German orchards but enhanced their abundance in Sweden, and high natural plant species richness tended to reduce predatory bug abundance in Sweden and IP orchards in Spain. We conclude that predatory arthropod communities and influences of local and landscape factors are strongly shaped by orchard management, and that the influence of management differs between countries. Our results indicate that organic management improves the living conditions for effective predator communities. © 2018 Elsevier B.V.
Harjung A., Ejarque E., Battin T., Butturini A., Sabater F., Stadler M., Schelker J. (2019) Experimental evidence reveals impact of drought periods on dissolved organic matter quality and ecosystem metabolism in subalpine streams. Limnology and Oceanography. 64: 46-60.LinkDoi: 10.1002/lno.11018
Subalpine streams are predicted to experience lower summer discharge following climate change and water extractions. In this study, we aimed to understand how drought periods impact dissolved organic matter (DOM) processing and ecosystem metabolism of subalpine streams. We mimicked a gradient of drought conditions in stream-side flumes and evaluated implications of drought on DOM composition, gross primary production, and ecosystem respiration. Our experiment demonstrated a production and release of DOM from biofilms and leaf litter decomposition at low discharges, increasing dissolved organic carbon concentrations in stream water by up to 50%. Absorbance and fluorescence properties suggested that the released DOM was labile for microbial degradation. Dissolved organic carbon mass balances revealed a high contribution of internal processes to the carbon budget during low flow conditions. The flumes with low discharge were transient sinks of atmospheric CO2 during the first 2 weeks of drought. After this autotrophic phase, the metabolic balance of these flumes turned heterotrophic, suggesting a nutrient limitation for primary production, while respiration remained high. Overall our experimental findings suggest that droughts in subalpine streams will enhance internal carbon cycling by transiently increasing primary production and more permanently respiration as the drought persists. We propose that the duration of a drought period combined with inorganic nutrient availability are key variables that determine if more carbon is respired in situ or exported downstream. © 2018 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.
Harjung A., Perujo N., Butturini A., Romaní A.M., Sabater F. (2019) Responses of microbial activity in hyporheic pore water to biogeochemical changes in a drying headwater stream. Freshwater Biology. 64: 735-749.LinkDoi: 10.1111/fwb.13258
Microbial heterotrophic activity is a major driver of nutrient and organic matter processing in the hyporheic zone of headwater streams. Additionally, the hyporheic zone might provide refuge for microbes when surface flow ceases during drought events. We investigated chemical (organic and inorganic nutrients) and microbiological parameters (bacterial cell concentration, live–dead ratios, and extracellular enzyme activities) of surface and interstitial pore water in a period of progressive surface-hyporheic disconnection due to summer drying. The special situation of the chosen study reach, where groundwater mixing is impeded by the bedrock forming a natural channel filled with sediment, allowed as to study the transformation of these parameters along hyporheic flow paths. The chemical composition of the hyporheic pore water reflected the connectivity with the surface water, as expressed in the availability of nitrate and oxygen. Conversely, microbiological parameters in all hyporheic locations were different from the surface waters, suggesting that the microbial activity in the water changes rapidly once the water enters the hyporheic zone. This feature was principally manifested in higher live–dead ratios and lower leucine aminopeptidase (an activity related to nitrogen acquisition) in the hyporheic pore waters. Overall, bacterial cell concentration and extracellular enzyme activities increased along hyporheic flow paths, with a congruent decrease in inorganic nutrients and dissolved organic matter quantity and apparent molecular size. Our findings show two important functions of the hyporheic zone during drought: (1) deeper (−50 cm) water-saturated layers can act as a refuge for microbial activity; and (2) the hyporheic zone shows high rates of carbon and nitrogen turnover when water residence times are longer during drought. These rates might be even enhanced by an increase in living microbes in the remaining moist locations of the hyporheic zone. © 2019 The Authors. Freshwater Biology Published by John Wiley & Sons Ltd.
Hermoso V., Morán-Ordóñez A., Canessa S., Brotons L. (2019) A dynamic strategy for EU conservation. Science. 363: 592-593.LinkDoi: 10.1126/science.aaw3615
[No abstract available]
Herrando S., Titeux N., Brotons L., Anton M., Ubach A., Villero D., García-Barros E., Munguira M.L., Godinho C., Stefanescu C. (2019) Contrasting impacts of precipitation on Mediterranean birds and butterflies. Scientific Reports. 9: 0-0.LinkDoi: 10.1038/s41598-019-42171-4
The climatic preferences of the species determine to a large extent their response to climate change. Temperature preferences have been shown to play a key role in driving trends in animal populations. However, the relative importance of temperature and precipitation preferences is still poorly understood, particularly in systems where ecological processes are strongly constrained by the amount and timing of rainfall. In this study, we estimated the role played by temperature and precipitation preferences in determining population trends for birds and butterflies in a Mediterranean area. Trends were derived from long-term biodiversity monitoring data and temperature and precipitation preferences were estimated from species distribution data at three different geographical scales. We show that population trends were first and foremost related to precipitation preferences both in birds and in butterflies. Temperature preferences had a weaker effect on population trends, and were significant only in birds. The effect of precipitation on population trends operated in opposite directions in the two groups of species: butterfly species from arid environments and bird species from humid habitats are decreasing most. Our results indicate that, although commonly neglected, water availability is likely an important driver of animal population change in the Mediterranean region, with highly contrasting impacts among taxonomical groups. © 2019, The Author(s).
Hrafnkelsdottir B., Sigurdsson B.D., Oddsdottir E.S., Sverrisson H., Halldorsson G. (2019) Winter survival of Ceramica pisi (Lepidoptera: Noctuidae) in Iceland. Agricultural and Forest Entomology. 21: 219-226.LinkDoi: 10.1111/afe.12323
The broom moth Ceramica pisi, a native species in Iceland, has shown a marked expansion from south Iceland towards the north, concurrent with increasing temperatures. Winter temperatures have increased more than summer temperatures in Iceland and, in the present study, the hypothesis was that the winter warming has facilitated the range shift of C. pisi. Winter survival of pupae in Iceland was studied in the laboratory. Pupae were collected in the autumn of 2012 at five separate locations, then weighed and placed at temperatures from −6 to −18 °C. One month after the sub-zero treatments, the pupae were placed at room temperature and pupal emergence was recorded. No significant effect of sub-zero treatments on the survival of C. pisi pupae was found. The primary hypothesis of the present study was therefore rejected. The major factor affecting low temperature survival of C. pisi pupae, however, was their autumn weight. The response was sigmoid and the 5%, 50% and 95% likelihoods for winter survival were at 157, 274 and 393 mg autumn pupal mass, respectively. This finding indicates that factors other than winter temperature, such as summer available thermal budget for larval growth, may be a limiting factor to the spread of C. pisi in Iceland. © 2019 The Royal Entomological Society
Hu M., Peñuelas J., Sardans J., Huang J., Li D., Tong C. (2019) Effects of nitrogen loading on emission of carbon gases from estuarine tidal marshes with varying salinity. Science of the Total Environment. 667: 648-657.LinkDoi: 10.1016/j.scitotenv.2019.02.429
Estuarine tidal marshes sequester significant quantities of carbon and are suffering from anthropogenic nitrogen (N) enhancement. However, the effects of this N loading on carbon gas emissions from freshwater-oligohaline tidal marshes are unknown. In this paper, we report on our evaluation of the effects of a N gradient (0, 24, 48 and 96 g NH 4 NO 3 –N m −2 y −1 ) on the methane (CH 4 ) and carbon dioxide (CO 2 ) emissions from freshwater and oligohaline tidal marshes in the Min River estuary, southeast China. On an annual scale, the oligohaline marsh has significantly higher CO 2 emissions, while it has slightly lower CH 4 emissions relative to freshwater marsh. The addition of N increased CH 4 emission from the freshwater marsh and decreased CH 4 emission from the oligohaline marsh, although there was no statistically significant difference in CH 4 emission between either of the two marshes and the control. The addition of 96 g NH 4 NO 3 –N m −2 y −1 significantly increased CO 2 emission from the freshwater marsh, while it did not significantly influence CO 2 emission from the oligohaline marsh. CH 4 and CO 2 emission levels were positively correlated with soil temperature under all conditions. The CH 4 flux resulting from both the control and the addition of N was negatively correlated with porewater SO 4 2− and Cl − concentrations and soil EC in the oligohaline marsh. Overall, N addition significantly increased carbon gas emissions under freshwater conditions while slightly inhibiting carbon gas emissions from the oligohaline marsh. Our findings suggested that even under low salinity conditions, the effects of N loading on CH 4 and CO 2 emissions from freshwater and oligohaline tidal marshes can vary. We propose that the addition of N to estuarine tidal marshes has a significant effect on the carbon cycle and promotes soil carbon loss, phenomena which may be influenced by salinity. © 2019 Elsevier B.V.
Huang M., Piao S., Ciais P., Peñuelas J., Wang X., Keenan T.F., Peng S., Berry J.A., Wang K., Mao J., Alkama R., Cescatti A., Cuntz M., De Deurwaerder H., Gao M., He Y., Liu Y., Luo Y., Myneni R.B., Niu S., Shi X., Yuan W., Verbeeck H., Wang T., Wu J., Janssens I.A. (2019) Air temperature optima of vegetation productivity across global biomes. Nature Ecology and Evolution. 3: 772-779.LinkDoi: 10.1038/s41559-019-0838-x
The global distribution of the optimum air temperature for ecosystem-level gross primary productivity (Topteco) is poorly understood, despite its importance for ecosystem carbon uptake under future warming. We provide empirical evidence for the existence of such an optimum, using measurements of in situ eddy covariance and satellite-derived proxies, and report its global distribution. Topteco is consistently lower than the physiological optimum temperature of leaf-level photosynthetic capacity, which typically exceeds 30 °C. The global average Topteco is estimated to be 23 ± 6 °C, with warmer regions having higher Topteco values than colder regions. In tropical forests in particular, Topteco is close to growing-season air temperature and is projected to fall below it under all scenarios of future climate, suggesting a limited safe operating space for these ecosystems under future warming. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
Lang A., Kallhardt F., Lee M.S., Loos J., Molander M.A., Muntean I., Pettersson L.B., Rákosy L., Stefanescu C., Messéan A. (2019) Monitoring environmental effects on farmland Lepidoptera: Does necessary sampling effort vary between different bio-geographic regions in Europe?. Ecological Indicators. 102: 791-800.LinkDoi: 10.1016/j.ecolind.2019.03.035
In agro-ecosystems, environmental monitoring is fundamental to detect and survey changes related to land use change and management practices. Butterflies and moths have often been suggested as suitable indicators for monitoring environmental effects on biodiversity in farmlands. Here, we estimated the required sample size and monitoring effort necessary to run a Lepidoptera survey in European farmland, assessing in particular if monitoring investment would differ between representative bio-geographical regions. We operated linear 1-km long transect routes in farmland of Romania, Spain and Sweden from 2013 to 2015, and recorded butterflies and burnet moths (Papilionoidea, Zygaenidae). The transects were walked back and forth four times a season, and replicated yearly. The lepidopteran diversity was high in farmlands of Romania and Spain, but comparatively low in Sweden. The coefficient of variation (CV) of recorded species number differed between countries being lowest in Sweden and highest in Spain. In general, the CV dropped above a transect length of 400–800 m, thus indicating an increase in statistical power. Assuming a non-parametric test for matched samples, power calculations were conducted with the raw count data and with log-transformed count data for comparison. When using log-transformed data, the required sample size to detect an effect was less than 10 transects per country or region (in order to detect a 10% loss of species or a decrease of 30% in total abundance). Specific subgroups of species, e.g. protected species or specific indicator groups, showed a higher variance, thus requiring a higher sample size to detect effects ranging from 12 to 16 transects (equivalent to 21–29 working days per country and year). When using original, untransformed count data a considerably larger sample size would be needed. Actual time to be invested in field work differed between countries due to contrasting regional constraints and conditions. Nevertheless, the final monitoring effort in working days was similar between countries as the factors involved balanced out each other, in particular due to the differing year-to-year variations. Our study demonstrated the feasibility of an environmental monitoring programme in arable land using farmland butterflies across Europe. We present a suitable approach and guidelines as well as the necessary effort to be invested in future Europe-wide monitoring programmes of butterflies in agro-ecosystems, based on predictions of statistical power. © 2019
Lanzas M., Hermoso V., de-Miguel S., Bota G., Brotons L. (2019) Designing a network of green infrastructure to enhance the conservation value of protected areas and maintain ecosystem services. Science of the Total Environment. 651: 541-550.LinkDoi: 10.1016/j.scitotenv.2018.09.164
There is a growing demand for holistic landscape planning to enhance sustainable use of ecosystem services (ESS) and maintenance of the biodiversity that supports them. In this context, the EU is developing policy to regulate the maintenance of ESS and enhance connectivity among protected areas (PAs). This is known as the network of Green Infrastructure (GI). However, there is not a working framework defined to plan the spatial design of such network of GI. Here, we use the software Marxan with Zones, to prioritize the spatial distribution of different management zones that accommodate the needs of a network of GI. These zones included a conservation zone, mainly devoted to protecting biodiversity, a GI zone, that aimed at connecting PAs and maintaining regulating and cultural ESS; and a management zone devoted to exploiting provisioning ESS. We performed four planning scenarios that distribute the targets for ESS and biodiversity in different ways across management zones. We also conducted a sensitivity analysis by increasing ESS targets to explore trade-offs that may occur when managing together biodiversity and ESS. We use Catalonia (northeastern Spain) as a case study. We found that the representation of ESS could be achieved for intermediate targets in all scenarios. There was, however, a threshold on these targets over which trade-offs appeared between maintaining regulating and cultural ESS and biodiversity versus getting access to provisioning ESS. These “thresholds values” were displaced towards higher ESS targets when we moved from more strict to more flexible planning scenarios (i.e., scenarios that allowed mixing representation of objectives for biodiversity and ESS within the same zone). This methodological approach could help design a framework to integrate biodiversity and ESS management in holistic plans and decision making and, at the same time, meeting European mandates concerning the design of GI networks, or similar needs elsewhere. © 2018 Elsevier B.V.
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