Template-free inorganic synthesis of silica-based nanotubes and their self-assembly to mesocrystals

A novel synthesis approach for silica-based nanotubes (NTs) was discovered in the purely inorganic system containing the molecular compounds OP(NH2)3, SP(NH2)3 and SiCl4 in evacuated and sealed silica glass ampoules. Without any solvent or structure directing template the amorphous NTs self-organise to form orthogonally ordered, 3D hyperbranched mesocrystals, exhibiting an interesting material for nanofluidic device applications

Functional microbial community response to nutrient pulses by artificial groundwater recharge practice in surface soils and subsoils

Subsurface microorganisms are essential constituents of the soil purification processes associated with groundwater quality. In particular, soil enzyme activity determines the biodegradation of organic compounds passing through the soil profile. Transects from surface soil to a depth of 3.5 m were investigated for microbial and chemical soil characteristics at two groundwater recharge sites and one control site. The functional diversity of the microbial community was analyzed via the activity of eight enzymes. Acid phosphomonoesterase was dominant across sites and depths, followed by l-leucine aminopeptidase and β-glucosidase. Structural [e.g. phospholipid fatty acid (PLFA) pattern] and functional microbial diversities were linked to each other at the nonwatered site, whereas amendment with nutrients (DOC, NO3−) by flooding uncoupled this relationship. Microbial biomass did not differ between sites, whereas microbial respiration was the highest at the watered sites. Hence, excess nutrients available due to artificial groundwater recharge could not compensate for the limitation by others (e.g. phosphorus as assigned by acid phosphomonoesterase activity). Instead, at a similar microbial biomass, waste respiration via overflow metabolism occurred. In summary, ample supply of carbon by flooding led to a separation of decomposition and microbial growth, which may play an important role in regulating purification processes during groundwater recharg

Design and Manual to Construct Rainout-Shelters for Climate Change Experiments in Agroecosystems

Climate change models predict reduced summer precipitations for most European countries, including more frequent and extreme summer droughts. Rainout-shelters which intercept part of the natural precipitation provide an effective tool to investigate effects of different precipitation levels on biodiversity and ecosystem functioning. In this study, we evaluate and describe in detail a fixed-location rainout shelter (2.5×2.5m) with partial interception of natural rainfall. We provide a complete parts list, a construction manual and detailed CAD drawings allowing to rebuild and use these shelters for rainfall manipulation studies. In addition, we describe a rainout-shelter control treatment giving the possibility to quantify and account for potential shelter artifacts. To test the rainout-shelters, we established the following three treatments each in eight winter wheat plots of the agricultural long-term farming system comparison trial DOK in Therwil (Switzerland): (1) A rainout-shelter with 65% interception of rainfall, (2) a rainout-shelter control without interception of rainfall, and (3) an ambient control. The rainout-shelter effectively excluded 64.9% of the ambient rainfall, which is very close to the a priori calculated exclusion of 65.1%. In comparison to the ambient control plots, gravimetric soil moisture decreased under the rainout-shelter by a maximum of 11.1 percentage points. Air temperature under the rainout-shelter differed little from the ambient control (−0.55◦C in 1.2m height and +0.19◦C in 0.1m height), whereas soil temperatures were slightly higher in periods of high ambient temperature (+1.02◦C), but remained basically unaffected in periods of low ambient temperature (+0.14◦C). A maximum edge effect of 0.75m defined a sampling area of 1 × 1m under the rainout-shelter. The rainout-shelters presented here, proved to sustain under heavy weather and they were well-suited to be used in agricultural fields where management operations require the removal of the rainout-shelters for management operations. Overall, the results confirmed the good performance of the presented rainout-shelters regarding rainout-shelter artifacts, predictable rain exclusion, and feasibility for experimental studies in agricultural fields

Tropical Andean Forests Are Highly Susceptible to Nutrient Inputs - Rapid Effects of Experimental N and P Addition to an Ecuadorian Montane Forest

Tropical regions are facing increasing atmospheric inputs of nutrients, which will have unknown consequences for the structure and functioning of these systems. Here, we show that Neotropical montane rainforests respond rapidly to moderate additions of N (50 kg ha−1 yr−1) and P (10 kg ha−1 yr−1). Monitoring of nutrient fluxes demonstrated that the majority of added nutrients remained in the system, in either soil or vegetation. N and P additions led to not only an increase in foliar N and P concentrations, but also altered soil microbial biomass, standing fine root biomass, stem growth, and litterfall. The different effects suggest that trees are primarily limited by P, whereas some processes—notably aboveground productivity—are limited by both N and P. Highly variable and partly contrasting responses of different tree species suggest marked changes in species composition and diversity of these forests by nutrient inputs in the long term. The unexpectedly fast response of the ecosystem to moderate nutrient additions suggests high vulnerability of tropical montane forests to the expected increase in nutrient inputs

Interactions of Mycorrhiza and Protists in the Rhizosphere Systemically Alter Microbial Community Composition, Plant Shoot-to-Root Ratio and Within-Root System Nitrogen Allocation

Arbuscular mycorrhizal fungi (AMF) are important symbionts for plant nutrient uptake, but their exact role in plant nitrogen (N) nutrition is unclear. Protists on the other hand play an acknowledged role in plant N acquisition, and there is increasing evidence for a close interaction with AMF. In a split root set up, we investigated the distinct roles of mycorrhiza (Rhizophagus irregularis), protists (Acanthamoeba castellanii), and their interaction on plant N uptake, within-root system allocation patterns, and shoot-to-root ratio of winter wheat. In addition, we applied a quantitative metabolomics approach to characterize associated changes in soil microbial communities by microbial phospholipid fatty acid (PLFA) analysis from rhizosphere soil. AMF markedly altered plant shoot-to-root allometry by reducing root biomass of wheat, and mycorrhiza partly took over root system functioning. Protists promoted shoot and root growth, and improved plant N uptake by the release of N from consumed bacterial biomass, a mechanism known as microbial loop. The shoot system however responded little to these alterations of the root system and of the rhizosphere community composition, indicating that the plants optimized shoot growth despite varying investment into roots. Mycorrhiza reduced root biomass and plant N, especially in the combined treatments with protists by changing within root system allocation of N and root biomass. These systemic effects on root allocation pattern suggest that mycorrhiza also gained control over N provided by protist grazers. Protists and mycorrhiza altered rhizosphere bacterial communities in contrasting but consistent ways as shown by quantitative shifts in microbial PLFA profiles. Remarkably, the changes in bacterial community composition were systemically conveyed within the root system to the split-root chamber where the symbionts were lacking. Accordingly the synergistic effects of protists and mycorrhiza indicated systemic effects on nutrient- and on root-allocation within root systems as an emergent property that could not be predicted from single treatments with mycorrhiza or protists alone. The tight plant and microbial feed backs uncovered in this study have far reaching implications for understanding the assembly of plant microbiomes, and testify central roles of both protists and mycorrhizas in the assembly process

Changes in herbivore control in arable fields by detrital subsidies depend on predator species and vary in space

Prey from the decomposer subsystem may help sustain predator populations in arable fields. Adding organic residues to agricultural systems may therefore enhance pest control. We investigated whether resource addition (maize mulch) strengthens aboveground trophic cascades in winter wheat fields. Evaluating the flux of the maize-borne carbon into the food web after 9 months via stable isotope analysis allowed differentiating between prey in predator diets originating from the above- and belowground subsystems. Furthermore, we recorded aphid populations in predator-reduced and control plots of no-mulch and mulch addition treatments. All analyzed soil dwelling species incorporated maize-borne carbon. In contrast, only 2 out of 13 aboveground predator species incorporated maize carbon, suggesting that these 2 predators forage on prey from the above- and belowground systems. Supporting this conclusion, densities of these two predator species were increased in the mulch addition fields. Nitrogen isotope signatures suggested that these generalist predators in part fed on Collembola thereby benefiting indirectly from detrital resources. Increased density of these two predator species was associated by increased aphid control but the identity of predators responsible for aphid control varied in space. One of the three wheat fields studied even lacked aphid control despite of mulch-mediated increased density of generalist predators. The results suggest that detrital subsidies quickly enter belowground food webs but only a few aboveground predator species include prey out of the decomposer system into their diet. Variation in the identity of predator species benefiting from detrital resources between sites suggest that, depending on locality, different predator species are subsidised by prey out of the decomposer system and that these predators contribute to aphid control. Therefore, by engineering the decomposer subsystem via detrital subsidies, biological control by generalist predators may be strengthened

Soil microbial responses to multiple global change factors as assessed by metagenomics

Anthropogenic activities impose multiple concurrent pressures on soils globally, but responses of soil microbes to multiple global change factors are poorly understood. Here, we apply 10 treatments (warming, drought, nitrogen deposition, salinity, heavy metal, microplastics, antibiotics, fungicides, herbicides and insecticides) individually and in combinations of 8 factors to soil samples, and monitor their bacterial and viral composition by metagenomic analysis. We recover 742 mostly unknown bacterial and 1865 viral Metagenome-Assembled Genomes (MAGs), and leverage them to describe microbial populations under different treatment conditions. The application of multiple factors selects for prokaryotic and viral communities different from any individual factor, favouring the proliferation of potentially pathogenic mycobacteria and novel phages, which apparently play a role in shaping prokaryote communities. We also build a 25 M gene catalog to show that multiple factors select for metabolically diverse, sessile and non-biofilm-forming bacteria with a high load of antibiotic resistance genes. Finally, we show that novel genes are relevant for understanding microbial response to global change. Our study indicates that multiple factors impose selective pressures on soil prokaryotes and viruses not observed at the individual factor level, and emphasizes the need of studying the effect of concurrent global change treatments

Rapid diversification of the Australian <i>Amitermes</i> group during late Cenozoic climate change

Late Cenozoic climate change led to the progressive aridification of Australia over the past 15 million years. This gradual biome turnover fundamentally changed Australia’s ecosystems, opening new niches and prompting diversification of plants and animals. One example are termites of the Australian Amitermes group (AAG), consisting of the Australian Amitermes and affiliated genera. Although the most speciose and diverse higher termite group in Australia, little is known about its evolutionary history. We used ancestral range reconstruction and diversification analyses to illuminate 1) phylogenetic relationships of the AAG, 2) biogeographical processes leading to the current continent-wide distribution and 3) timing and pattern of diversification in the context of late Cenozoic climate change. By estimating the largest time-calibrated phylogeny for this group to date, we demonstrate monophyly of the AAG and confirm that their ancestor arrived in Australia ~11–10 million years ago (Mya) from Southeast Asia. Ancestral range reconstruction indicates that Australia’s monsoon region was the launching point for a continental radiation shaped by dispersal and within-biome speciation rather than vicariance. We found that multiple arid-zone species diversified from mesic and tropical ancestors in the Plio-Pleistocene, but also observed diversification in the opposite direc-tion. Finally, we show that diversification steadily increased from ~8 to 9 Mya during the ‘Hill Gap’ and accelerated from ~4 Mya in concert with major ecological change during the Pliocene. Consistent with rapid diversification, species accumulation then slowed down into the present, likely caused by progressive niche saturation. This study provides a stepping stone for predicting future responses of Australia’s termite fauna in the face of human-mediated climate change.Open-Access-Publikationsfonds 202

Micro- and Macroscale Changes in Density and Diversity of Testate Amoebae of Tropical Montane Rain Forests of Southern Ecuador

We investigated changes in diversity and density of testate amoebae in epiphytes of trees in tropical montane rain forests of southern Ecuador. Local – microscale [height on tree trunk of 0 (base of tree trunk), 1 and 2 m; TH I, TH II and TH III, respectively] and regional – macroscale (forests at 1000, 2000 and 3000 m) changes were investigated. At the macroscale diversity and density of testate amoebae peaked at 2000 m. At the microscale diversity reached a maximum at TH I, whereas density reached a maximum at TH III. The percentage of empty shells at the macroscale was at a maximum at 2000 m and at the microscale at TH I, whereas the percentage of live cells was at a maximum at 3000 m and at TH III. The diversity of testate amoebae in epiphytes found in the present study was high (113 species). However, only two to nine species were dominant representing 54–85 percent of total living testate amoebae. The results suggest significant variations in density and diversity of testate amoebae at both the micro- and macroscale. However, for testate amoebae density the macroscale appears most important whereas changes in diversity are more pronounced at the microscal