• Global Warming:

    the threat of a permafrost Carbon – climate feedback

  • We develop and improve

    stable isotopes techniques for ecological applications

  • Plants, fungi and bacteria interact

    at the root-soil interface

  • Probing the future:

    Climate Change experiments

  • Soil is fundamental to human life

  • Tropical rainforests

    hold the key to global net primary productivity

TER News

Latest publications

Resistant Soil Microbial Communities Show Signs of Increasing Phosphorus Limitation in Two Temperate Forests After Long-Term Nitrogen Addition

Forest soils harbor diverse microbial communities responsible for the cycling of elements including carbon (C), nitrogen (N), and phosphorus (P). Conversely, anthropogenic N deposition can negatively feed back on soil microbes and reduce soil organic matter (SOM) decomposition. Mechanistically, this can include reductions of decomposer biomass, especially fungi, and decreases in activities of lignin-modifying enzyme (LMEs). Moreover, N inputs can lower resource C:N and thus decrease the C:N imbalance between microbial decomposers and their resources. As a result, microbially-mediated decomposition might slow down, resulting in larger SOM pools with consequences for ecosystem nutrition and climate regulation. Here, we studied the long-term impact of experimental N addition on soil microbes and microbially-mediated decomposition in two coniferous forests in Switzerland and Denmark. We measured microbial biomass C and N, phospholipid fatty acid (PLFA) biomarkers and potential enzyme activities related to C, N, and P acquisition along the topsoil profile (0–30 cm). In particular, we investigated shifts in microbial C:N homeostasis and relative C:N:P limitation. Contrary to prevailing theory, microbial biomass and community composition were remarkably resistant against two decades of 750 and 1,280 kg ha−1 of cumulative N inputs at the Swiss and Danish site, respectively. While N reduced fungal-specific PLFAs and lowered fungi-to-bacteria (F:B) ratios in some (mainly organic) horizons where soil organic carbon (SOC) has accumulated, it increased F:B ratios in other (mainly mineral) horizons where SOC has declined. We did not find a consistent reduction of LME activities in response to N. Rather, relationships between LME activities and SOC concentrations were largely unaffected by N addition. This questions prevalent theories of lignin decomposition and SOC storage under elevated N inputs. By using C:N stoichiometry, we further show that microbial communities responded in part non-homeostatically to decreasing resource C:N, in addition to a likely increase in their carbon use efficiency and a decrease in nitrogen use efficiency. While the expected increased allocation to C- and decreased allocation to N-acquiring enzymes was not found, microbial investment in P acquisition (acid phosphatase activity) increased in the nutrient-poor Podzol (but not in the nutrient-rich Gleysol). Enzyme vector analysis showed decreasing C but increasing P limitation of soil microbial communities at both sites. We conclude that simulated N deposition led to physiological adaptations of soil microbial communities across the topsoil profile in two independent experiments, with long-term implications for tree nutrition and SOC sequestration. However, we expect that microbial adaptations are not endless and may reach a tipping point when ecosystems experience nitrogen saturation.

Forstner SJ, Wechselberger V, Stecher S, Müller S, Keiblinger KM, Wanek W, Schleppi P, Gundersen P, Tatzber M, Gerzabek MH, Zechmeister­‐Boltenstern S
2019 - Frontiers in Forests and Global Change, 2: Article 73

Nutrient scarcity strengthens soil fauna control over leaf litter decomposition in tropical rainforests

Soil fauna is a key control of the decomposition rate of leaf litter, yet its
interactions with litter quality and the soil environment remain elusive. We
conducted a litter decomposition experiment across different topographic
levels within the landscape replicated in two rainforest sites providing natural
gradients in soil fertility to test the hypothesis that low nutrient availability in
litter and soil increases the strength of fauna control over litter decomposition.
We crossed these data with a large dataset of 44 variables characterizing
the biotic and abiotic microenvironment of each sampling point and found
that microbe-driven carbon (C) and nitrogen (N) losses from leaf litter were
10.1 and 17.9% lower, respectively, in the nutrient-poorest site, but this
among-site difference was equalized when meso- and macrofauna had
access to the litterbags. Further, on average, soil fauna enhanced the rate of
litter decomposition by 22.6%, and this contribution consistently increased
as nutrient availability in the microenvironment declined. Our results indicate
that nutrient scarcity increases the importance of soil fauna on C and N
cycling in tropical rainforests. Further, soil fauna is able to equalize differences
in microbial decomposition potential, thus buffering to a remarkable extent
nutrient shortages at an ecosystem level.

Peguero G, Sardans J, Asensio D, Fernández-Martínez M, Gargallo-Garriga A, Grau O, Llusià J, Margalef O, Márquez L, Ogaya R, Urbina I, Courtois EA, Stah C, Van Langenhove L, Verryckt LT, Richter A, anssens IA, Peñuelas J
2019 - Proceedings of the Royal Society B: Biological Sciences, 286: Article 20191300

Increased risk of phosphorus and metal leaching from paddy soils after excessive manure application: Insights from a mesocosm study

Livestock manure has gradually become an alternative fertilizer for maintaining soil fertility, whereas excessive application of manure leads to the release of phosphorus (P) and toxic metals that may cause complex environmental risks. To investigate the accumulation and migration of P within soil profiles, a mesocosm experiment was conducted to analyze the content and leaching of soil P, metals, and dissolved organic carbon after different fertilization treatments, including control (no fertilizer, CK), chemical fertilizer (CF), chemical fertilizer combined low (CF + LPM) and high (CF + HPM) rate of manure application. Results showed that a high rate of manure application significantly enhanced the accumulation of total soil P (by ~14%) and P availability (easily-available P, by ~24%; Olsen-P, by ~20%) in topsoil, and also increased the content of easily-available organic P (EA-Po) in both topsoil and subsoil compared to the CK treatment. The migration of dissolved inorganic and organic P (DIP and DOP) in leachate within soil profiles was strengthened by manure application. Moreover, significant positive correlations between P, metals, and dissolved organic carbon (DOC) in leachate indicated that downward co-migration occurred within the soil profiles, and also suggested that excessive manure application can intensify the risk of P loss by increasing the migration of manure-derived DOC. Overall, our findings provide insights into P accumulation and migration within soil profiles after excessive manure application, which is useful for predicting the potential risk of P and metal leaching from paddy soils.

Liu XP, Bi QF, Qiu LL, Li KJ, Yang XR, Lin XY
2019 - Science of The Total Environment, 666: 778-785

Lecture series

Microbial ecology of nitrogen cycling in paddy soils

Yong-Guan Zhu
Research Centre for Eco-Environmental Sciences & Institute of Urban Environment, Chinese Academy of Sciences
09:00 h
Lecture Hall HS 5, UZA2 (Geocentre), Althanstrasse 14, 1090 Vienna

How to meet the Paris 2°C target: Which are the main constraints that will need to be overcome?

Ivan Janssens
Centre of Excellence of Global Change Ecology, University of Antwerp, Belgium
12:00 h
Lecture Hall HS2 (UZA 1), Althanstraße 14, 1090 Vienna

Soil C dynamics –when are microbial communities in control?

Naoise Nunan
Institute of Ecology and Environmental Sciences IEES Paris, France
12:00 h
Lecture Hall HS2 (UZA 1), Althanstraße 14, 1090 Vienna