scholarly journals Nonlinear, interacting responses to climate limit grassland production under global change

2016 ◽  
Vol 113 (38) ◽  
pp. 10589-10594 ◽  
Author(s):  
Kai Zhu ◽  
Nona R. Chiariello ◽  
Todd Tobeck ◽  
Tadashi Fukami ◽  
Christopher B. Field

Global changes in climate, atmospheric composition, and pollutants are altering ecosystems and the goods and services they provide. Among approaches for predicting ecosystem responses, long-term observations and manipulative experiments can be powerful approaches for resolving single-factor and interactive effects of global changes on key metrics such as net primary production (NPP). Here we combine both approaches, developing multidimensional response surfaces for NPP based on the longest-running, best-replicated, most-multifactor global-change experiment at the ecosystem scale—a 17-y study of California grassland exposed to full-factorial warming, added precipitation, elevated CO2, and nitrogen deposition. Single-factor and interactive effects were not time-dependent, enabling us to analyze each year as a separate realization of the experiment and extract NPP as a continuous function of global-change factors. We found a ridge-shaped response surface in which NPP is humped (unimodal) in response to temperature and precipitation when CO2 and nitrogen are ambient, with peak NPP rising under elevated CO2 or nitrogen but also shifting to lower temperatures. Our results suggest that future climate change will push this ecosystem away from conditions that maximize NPP, but with large year-to-year variability.

2020 ◽  
Author(s):  
Hans De Boeck ◽  
Simon Reynaert ◽  
Ivan Nijs ◽  
Karel Klem ◽  
Klaus Steenberg Larsen ◽  
...  

<p>Human activities are directly and indirectly generating major environmental pressures on ecosystems worldwide through climate change, pollution and other global changes. Altogether, these changes result in a rapid erosion of biodiversity and a perturbation of ecological and agricultural systems and services, prompting urgent societal questions on how to retain or promote sustainable ecosystem services in a global change context. Understanding the responses of ecosystems to such pressures and perturbations, and developing adaptation strategies critically requires state-of-the-art experimental facilities that are able to simulate multiple global change factors. AnaEE (Analysis and Experimentation on Ecosystems) brings together such facilities in a European-wide infrastructure for experimental research on managed and unmanaged terrestrial and aquatic ecosystems. It assists and integrates four types of national platforms (Open-air, Enclosed, Analytical, and Modelling) and provides support to scientists who wish to engage in research projects using these platforms or the data they generate. These services are organised through the Central Hub and three Service Centres (Technology, Data and Modelling, Interface and Synthesis). This integrated approach improves the quality and availability of data and projections on ecosystem responses to global changes, enabling policy makers and stakeholders to make fact-based  decisions on how to sustainably manage ecosystem services. As an example, we shortly discuss the new open air FATI-platform (UAntwerp) in which ecosystems can be exposed to various combinations of precipitation change and warming, and present first results of a study on the impacts of precipitation regime changes on temperate grassland.</p>


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Saeed Shojaei ◽  
Zahra Kalantari ◽  
Jesús Rodrigo-Comino

AbstractSoil degradation due to erosion is a significant worldwide problem at different spatial (from pedon to watershed) and temporal scales. All stages and factors in the erosion process must be detected and evaluated to reduce this environmental issue and protect existing fertile soils and natural ecosystems. Laboratory studies using rainfall simulators allow single factors and interactive effects to be investigated under controlled conditions during extreme rainfall events. In this study, three main factors (rainfall intensity, inclination, and rainfall duration) were assessed to obtain empirical data for modeling water erosion during single rainfall events. Each factor was divided into three levels (− 1, 0, + 1), which were applied in different combinations using a rainfall simulator on beds (6 × 1 m) filled with soil from a study plot located in the arid Sistan region, Iran. The rainfall duration levels tested were 3, 5, and 7 min, the rainfall intensity levels were 30, 60, and 90 mm/h, and the inclination levels were 5, 15, and 25%. The results showed that the highest rainfall intensity tested (90 mm/h) for the longest duration (7 min) caused the highest runoff (62 mm3/s) and soil loss (1580 g/m2/h). Based on the empirical results, a quadratic function was the best mathematical model (R2 = 0.90) for predicting runoff (Q) and soil loss. Single-factor analysis revealed that rainfall intensity was more influential for runoff production than changes in time and inclination, while rainfall duration was the most influential single factor for soil loss. Modeling and three-dimensional depictions of the data revealed that sediment production was high and runoff production lower at the beginning of the experiment, but this trend was reversed over time as the soil became saturated. These results indicate that avoiding the initial stage of erosion is critical, so all soil protection measures should be taken to reduce the impact at this stage. The final stages of erosion appeared too complicated to be modeled, because different factors showed differing effects on erosion.


2018 ◽  
Vol 159 ◽  
pp. 209-224 ◽  
Author(s):  
Stefan Fronzek ◽  
Nina Pirttioja ◽  
Timothy R. Carter ◽  
Marco Bindi ◽  
Holger Hoffmann ◽  
...  

2018 ◽  
Vol 374 (1763) ◽  
pp. 20170405 ◽  
Author(s):  
Heather M. Kharouba ◽  
Jayme M. M. Lewthwaite ◽  
Rob Guralnick ◽  
Jeremy T. Kerr ◽  
Mark Vellend

Over the past two decades, natural history collections (NHCs) have played an increasingly prominent role in global change research, but they have still greater potential, especially for the most diverse group of animals on Earth: insects. Here, we review the role of NHCs in advancing our understanding of the ecological and evolutionary responses of insects to recent global changes. Insect NHCs have helped document changes in insects' geographical distributions, phenology, phenotypic and genotypic traits over time periods up to a century. Recent work demonstrates the enormous potential of NHCs data for examining insect responses at multiple temporal, spatial and phylogenetic scales. Moving forward, insect NHCs offer unique opportunities to examine the morphological, chemical and genomic information in each specimen, thus advancing our understanding of the processes underlying species’ ecological and evolutionary responses to rapid, widespread global changes. This article is part of the theme issue ‘Biological collections for understanding biodiversity in the anthropocene’.


2019 ◽  
Vol 11 (1) ◽  
pp. 369-390 ◽  
Author(s):  
Piero Calosi ◽  
Hollie M. Putnam ◽  
Richard J. Twitchett ◽  
Fanny Vermandele

Evolution, extinction, and dispersion are fundamental processes affecting marine biodiversity. Until recently, studies of extant marine systems focused mainly on evolution and dispersion, with extinction receiving less attention. Past extinction events have, however, helped shape the evolutionary history of marine ecosystems, with ecological and evolutionary legacies still evident in modern seas. Current anthropogenic global changes increase extinction risk and pose a significant threat to marine ecosystems, which are critical for human use and sustenance. The evaluation of these threats and the likely responses of marine ecosystems requires a better understanding of evolutionary processes that affect marine ecosystems under global change. Here, we discuss how knowledge of ( a) changes in biodiversity of ancient marine ecosystems to past extinctions events, ( b) the patterns of sensitivity and biodiversity loss in modern marine taxa, and ( c) the physiological mechanisms underpinning species’ sensitivity to global change can be exploited and integrated to advance our critical thinking in this area.


Author(s):  
S. Supharatid ◽  
J. Nafung ◽  
T. Aribarg

Abstract Five mainland SEA countries (Cambodia, Laos, Myanmar, Vietnam, and Thailand) are threatened by climate change. Here, the latest 18 Coupled Model Intercomparison Project Phase 6 (CMIP6) is employed to examine future climate change in this region under two SSP-RCP (shared socioeconomic pathway-representative concentration pathway) scenarios (SSP2-4.5 and SSP5-8.5). The bias-corrected multi-model ensemble (MME) projects a warming (wetting) over Cambodia, Laos, Myanmar, Vietnam, and Thailand by 1.88–3.89, 2.04–4.22, 1.88–4.09, 2.03–4.25, and 1.90–3.96 °C (8.76–20.47, 12.69–21.10, 9.54–21.10, 13.47–22.12, and 7.03–15.17%) in the 21st century with larger values found under SSP5-8.5 than SSP2-4.5. The MME model displays approximately triple the current rainfall during the boreal summer. Overall, there are robust increases in rainfall during the Southwest Monsoon (3.41–3.44, 8.44–9.53, and 10.89–17.59%) and the Northeast Monsoon (−2.58 to 0.78, −0.43 to 2.81, and 2.32 to 5.45%). The effectiveness of anticipated climate change mitigation and adaptation strategies under SSP2-4.5 results in slowing down the warming trends and decreasing precipitation trends after 2050. All these findings imply that member countries of mainland SEA need to prepare for appropriate adaptation measures in response to the changing climate.


2020 ◽  
Vol 12 (4) ◽  
pp. 2959-2970
Author(s):  
Maialen Iturbide ◽  
José M. Gutiérrez ◽  
Lincoln M. Alves ◽  
Joaquín Bedia ◽  
Ruth Cerezo-Mota ◽  
...  

Abstract. Several sets of reference regions have been used in the literature for the regional synthesis of observed and modelled climate and climate change information. A popular example is the series of reference regions used in the Intergovernmental Panel on Climate Change (IPCC) Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Adaptation (SREX). The SREX regions were slightly modified for the Fifth Assessment Report of the IPCC and used for reporting subcontinental observed and projected changes over a reduced number (33) of climatologically consistent regions encompassing a representative number of grid boxes. These regions are intended to allow analysis of atmospheric data over broad land or ocean regions and have been used as the basis for several popular spatially aggregated datasets, such as the Seasonal Mean Temperature and Precipitation in IPCC Regions for CMIP5 dataset. We present an updated version of the reference regions for the analysis of new observed and simulated datasets (including CMIP6) which offer an opportunity for refinement due to the higher atmospheric model resolution. As a result, the number of land and ocean regions is increased to 46 and 15, respectively, better representing consistent regional climate features. The paper describes the rationale for the definition of the new regions and analyses their homogeneity. The regions are defined as polygons and are provided as coordinates and a shapefile together with companion R and Python notebooks to illustrate their use in practical problems (e.g. calculating regional averages). We also describe the generation of a new dataset with monthly temperature and precipitation, spatially aggregated in the new regions, currently for CMIP5 and CMIP6, to be extended to other datasets in the future (including observations). The use of these reference regions, dataset and code is illustrated through a worked example using scatter plots to offer guidance on the likely range of future climate change at the scale of the reference regions. The regions, datasets and code (R and Python notebooks) are freely available at the ATLAS GitHub repository: https://github.com/SantanderMetGroup/ATLAS (last access: 24 August 2020), https://doi.org/10.5281/zenodo.3998463 (Iturbide et al., 2020).


2019 ◽  
Vol 62 (1) ◽  
pp. 43-50
Author(s):  
Ellen Schagerström ◽  
Tiina Salo

Abstract Fucus radicans is an endemic habitat-forming brown macroalga in the Baltic Sea that commonly complements its sexual reproduction with asexual reproduction. Asexual reproduction in F. radicans takes place through formation of adventitious branches (hereafter fragments), but the exact mechanisms behind it remain unknown. We assessed experimentally the importance of two environmental factors determining the re-attachment success of F. radicans fragments. By combining different light conditions (daylength and irradiance; high or low light) and water temperature (+14°C and +4°C), we mimicked ambient light and temperature conditions of winter, spring/autumn and summer for F. radicans. Fragments were able to re-attach in all tested conditions. Temperature and light had an interactive impact on re-attachment: the combination of high temperature and high light level resulted in the highest re-attachment success, while light level had no effects on re-attachment success in cooler water temperature and the re-attachment success in high temperature under low light levels was very low. The results suggest that rhizoid formation, and thus re-attachment success, may depend on the net primary production (metabolic balance) of the fragment. However, whether the re-attachment and asexual reproduction success simply depends on photosynthetic capacity warrants further mechanistic studies. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the dispersal capacity of this foundation species.


2021 ◽  
Author(s):  
Larisa Sogacheva ◽  
Anu-Maija Sundström ◽  
Timo H. Virtanen ◽  
Antti Arola ◽  
Tuukka Petäjä ◽  
...  

<p>The Pan-Eurasian Experiment Program (PEEX) is an interdisciplinary scientific program bringing together ground-based in situ and remote sensing observations, satellite measurements and modeling tools aiming to improve the understanding of land-water-atmosphere interactions, feedback mechanisms and their effects on the ecosystem, climate and society in northern Eurasia, Russia and China. In a view of the large area covering thousands of kilometres, large gaps will remain where no or little ground-based observational information will be available. The gap can partly be filled by satellite remote sensing of relevant parameters as regards atmospheric composition.</p><p>Biomass burning is a violent source of atmospheric pollutants. Fires and corresponding emissions to the atmosphere dramatically change the atmospheric composition in case of long-lasting fire events, which might cover extended areas. In the burned areas, CO2 exchange, as well as emissions of different compounds are getting to higher levels, which might contribute to climate change by changing the radiative budget through the aerosol-cloud interaction and cloud formation. In the boreal forest, after CO2, CO and CH4, the largest emission factors for individual species were formaldehyde, followed by methanol and NO2 (Simpson et al., ACP, 2011). The emitted long-life components, e.g., black carbon, might further be transported to the distant areas and measured at the surface far from the burned areas.</p><p>In the boreal forest region, fires are very common, very large and produce a lot of smoke. Boreal areas  have been burning regularly for thousands of years and is adapted to fires, which happen most often between May and October. In boreal ecosystems, future increases in air temperature may lengthen the fire season and increase the probability of fires, leading some to hypothesize a positive feedback between warming, fire activity, carbon loss, and future climate change (Kasischke et al., 2000). </p><p> During the last few decades, several burning episodes have been observed over PEEX area by satellites (as fire counts), specifically over Siberia and central Russia. The following information available from satellites will be utilized to reveal a connection between Fire activity and atmospheric composition <span>for the period 2002-2020 over the PEEX area:</span></p><ul><li>- Fire count, FRP and burned areas from MODIS</li> <li>- Absorbing Aerosol Index (AAI), multi-instrument (GOME-2, OMI, TOMS) product</li> <li>- CO from MOPPIT</li> <li>- HCHO and NO2 from OMI</li> </ul><p>Monthly temperature and humidity fields from ERA5 re-analysis will be also utilized to reveal if a connection exist between climate variables and occurrence and intensity of the forest fires.</p><p>Kasischke, B. J. Stocks: Fire, Climate Change, and Carbon Cycling in the Boreal Forest. M. M. Cadwellet al.,Eds., Ecological Studies (Springer, New York, 2000)</p><p>Simpson, I. J., Akagi, S. K., Barletta, B., Blake, N. J., Choi, Y., Diskin, G. S., Fried, A., Fuelberg, H. E., Meinardi, S., Rowland, F. S., Vay, S. A., Weinheimer, A. J., Wennberg, P. O., Wiebring, P., Wisthaler, A., Yang, M., Yokelson, R. J., and Blake, D. R.: Boreal forest fire emissions in fresh Canadian smoke plumes: C<sub>1</sub>-C<sub>10</sub> volatile organic compounds (VOCs), CO<sub>2</sub>, CO, NO<sub>2</sub>, NO, HCN and CH<sub>3</sub>CN, Atmos. Chem. Phys., 11, 6445–6463, https://doi.org/10.5194/acp-11-6445-2011, 2011.</p><p> </p>


2021 ◽  
Author(s):  
Tuula Larmola ◽  
Liisa Maanavilja ◽  
Heikki Kiheri ◽  
Mats Nilsson ◽  
Matthias Peichl

<p>In order to assess peatland carbon sink potential under multiple global change perturbations, we examined the individual and combined effects of long-term warming and enhanced nitrogen (N) and sulfur (S) deposition on ecosystem CO<sub>2 </sub>exchange at one of the longest-running experiments on peatlands, Degerö Stormyr poor fen, Sweden. The site has been treated with NH<sub>4</sub>NO<sub>3</sub> (15 times ambient annual wet deposition), Na<sub>2</sub>SO<sub>4</sub> (6 times ambient annual wet deposition) and elevated temperature (air +3.6 C) for 23 years. Gross photosynthesis, ecosystem respiration and net CO<sub>2</sub> exchange were measured weekly during June-August using chambers. After 23 years, two of the experimental perturbations: N addition and warming individually reduced net CO<sub>2</sub> uptake potential down to 0.3-0.4 fold compared to the control mainly due to lower gross photosynthesis. Under S only treatment ecosystem CO<sub>2</sub> fluxes were largely unaltered. In contrast, the combination of S and N deposition and warming led to a more pronounced effect and close to zero net CO<sub>2</sub> uptake potential or net C source. Our study emphasizes the value of the long-term multifactor experiments in examining the ecosystem responses: simultaneous perturbations can have nonadditive interactions that cannot be predicted based on individual responses and thus, must be studied in combination when evaluating feedback mechanisms to ecosystem C sink potential under global change.</p>


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