Reference: Shanahan, T.M.; Hughen, K.A.; McKay, N.P.; Overpeck, J.T.; Scholtz, C.A.; Gosling, W.D.;Miller, C.S.; Peck, J.A.; King, J.W.; Heil, C.W.
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Artikel
CO2 and fire influence tropical ecosystem stability in response to climate change
Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28–15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future. -
Artikel
Soil networks become more connected and take up more carbon as nature restoration progresses
Soil organisms have an important role in aboveground community dynamics and ecosystem functioning in terrestrial ecosystems. However, most studies have considered soil biota as a black box or focussed on specific groups, whereas little is known about entire soil networks. Here we show that during the course of nature restoration on abandoned arable land a compositional shift in soil biota, preceded by tightening of the belowground networks, corresponds with enhanced efficiency of carbon uptake. In mid- and long-term abandoned field soil, carbon uptake by fungi increases without an increase in fungal biomass or shift in bacterial-to-fungal ratio. The implication of our findings is that during nature restoration the efficiency of nutrient cycling and carbon uptake can increase by a shift in fungal composition and/or fungal activity. Therefore, we propose that relationships between soil food web structure and carbon cycling in soils need to be reconsidered.
LessReference:
Morriën, E., Hannula, S. E., Snoek, L. B., Helmsing, N. R., Zweers, H., de Hollander, M., ... van der Putten, W.H. (2017). Soil networks become more connected and take up more carbon as nature restoration progresses.Nature Communications, 8, [14349].
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Artikel
Many ways towards ‘solar fuel’
Abstract:
Future global needs for liquid energy carriers, commodity chemicals and renewable materials should no longer be covered by exploration of fossilized carbon deposits. Therefore, processes are urgently needed that can replace this source of carbon for the production of these materials. The alternative route of production most often referred to is via their synthesis from CO2 (and water), using the (free) energy of sunlight. This process has been intensely studied, particularly during the past decade, and has resulted in a wide range of proposed solutions. However, with the ultimate constraint that a limited surface area will be available on our planet to catch the necessary photons, the picture is emerging showing that three approaches turn out to be most promising to achieve commercial production of this range of products. Interestingly, they all exploit living cells to facilitate formation of essential, select, carbon–carbon bonds. In one approach, photovoltaic cells provide electricity to generate hydrogen that can be used for lithoautotrophy (or: ‘chemosynthesis’) in organisms like Cupriavidus or Clostridium. An alternative approach is to use solar-driven (i.e. large-surface area) photobioreactors for the growth of engineered cyanobacteria, to carry out ‘direct conversion’ of CO2 into products like ethanol, iso-butanol, lactic acid, etc. In a hybrid derivative of these two approaches renewable (solar) electricity may be converted into monochromatic light of ∼650 nm that is optimal to drive photosynthesis in cyanobacterial photobioreactors, equipped with internal LED illumination. Here we discuss strengths and weaknesses of these three approaches, analyse the range of products for which proof-of-principle production has been demonstrated, and compare a selection of such studies with respect to efficiency and productivity of the CO2-to-product conversion. As for all approaches large-scale application is crucial, we also discuss the pitfalls and limitations of their scale-up.D. Lips, J. M. Schuurmans, F. Branco dos Santos and K. J. Hellingwerf
Molecular Microbial Physiology Group, Faculty of Life Sciences, Swammerdam Institute of Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands. Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1090 XH, Amsterdam, The Netherlands -
Artikel
Strategieën voor circulaire afvalverwerking kunnen bijdragen aan duurzaamheidsdoelen van de stad
Er is ruimte voor verbetering in de afvalverwerking van de stad Amsterdam. Nu zijn afvalstromen in de stad vaak lineair en niet ingericht op duurzaamheid, en het recyclingpercentage van organisch afval is heel erg laag. Scheikundigen en bedrijfskundigen van de UvA sloegen de handen ineen en onderzochten strategieën voor stedelijk afvalbeheer voor een duurzame samenleving. Deze kunnen de gemeente helpen in het bereiken van haar ambitieuze doelen op het terrein van circulariteit.
L. Viva, F. Ciulli, A. Kolk en G. Rothenberg: ‘Designing Circular Waste Management Strategies: The Case of Organic Waste in Amsterdam’, in: Advanced Sustainable Systems (2020). DOI: 10.1002/adsu.202000023 (open access).
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