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Image showing tightly packed tree crowns in a natural tropical forest, for investigating the forest's structure. Tree crowns of different sizes are shown as spheres. Credit: André Künzelmann, UFZ Explaining the complex structure of tropical forests is one of the great challenges in ecology. An issue of special interest is the distribution of different sizes of trees, something which is of particular relevance for biomass estimates. A team of modellers from the Helmholtz Centre for Environmental Research (UFZ), working together with research partners, has now developed a new method which can be used to explain the tree size distribution in natural forests. To do so, the scientists use principles from stochastic geometry, as they have reported in a contribution to the Proceedings of the National Academy of Sciences (PNAS, Early Edition). Using this approach, it is possible to assess the structure of natural forests across the world more quickly, and produce more accurate biomass estimates. For over one hundred years, the distribution of different sizes of trees in forests has been one of the core attributes recorded by foresters and ecologists world-wide, as it can be used to derive many other structural features, such as biomass and productivity. "We wanted to explain this important pattern", said Dr. Franziska Taubert. Working with her UFZ colleagues Dr. Thorsten Wiegand and Prof. Andreas Huth, and other research partners in the Leipzig University of Applied Sciences (HTWK) and the Karlsruhe Institute of Technology (KIT), they have applied the theory of stochastic sphere packing, which is usually used in physics or chemistry. This theory describes how spheres can be placed in an available space. To apply the theory, the scientists randomly distributed tree crowns of different sizes in forest areas. These tree crowns were not permitted to overlap, - just like packing apples into a box. The distribution of the trees that have been successfully placed in the packing process was then used to determine the tree size distribution. "Many forest models are based on a dynamic approach: they take into account processes such as growth, mortality, regeneration and competition between trees for light, water and soil nutrients", said Taubert. "These models are complex and data-hungry", added Thorsten Wiegand," so we decided to take a radically different approach, which is fundamentally simpler and only based on spatial structures". This model approach proved its effectiveness by enabling observed forest structures, especially the tree size distribution, to be reproduced accurately. The rules of stochastic geometry are thereby enriched by tree geometry relationships, and the resulting tree packing system is compared to inventory data from tropical forests in Panama and Sri Lanka. Although one might imagine that a tropical forest is very tightly packed, the scientists came to a surprising conclusion: the packing density of the tree crowns, which averages 15 to 20%, is astonishingly low. "In particular, the upper and lower canopy levels are less tightly packed with tree crowns", said Taubert. High packing densities of around 60%, which are also possible according to stochastic geometry, only occur at tree heights between 25 and 40 meters. The findings concerning the distribution of tree crowns are important, because they can be used to draw conclusions about, for example, the carbon content or productivity of a forest. Using this modelling approach, the researchers were also able to show that the decisive factor in shaping the tree size distribution is competition for space. "In classical forest models", said Andreas Huth, "the trees instead compete for light, or water and nutrients". The theory opens up several new perspectives. The team plans to assess how the model can be applied to natural forests in the temperate and boreal zone. They believe that the model can be used to identify disturbed forests. "That is of special interest  because it will enable us to develop a disturbance index", said Taubert, "and to better interpret remote sensing observations by using the structure of natural forests as a reference". Another benefit of the new theory is that this simple forest packing model takes much less effort than classical forest models. The new approach is an important step toward identifying a minimal set of processes responsible for generating the spatial structure of natural forests. Explore further: Mixed-conifer forests at risk for high-severity wildfire More information: Franziska Taubert et al. The structure of tropical forests and sphere packings, Proceedings of the National Academy of Sciences (2015). DOI: 10.1073/pnas.1513417112


News Article
Site: phys.org

Colourful, low-intensity grasslands not only look attractive, they also offer valuable habitat for many plants and animals. Yet they have become rare in many places. To create more environments that contain grass and herbs, it is usually necessary to sow the appropriate plants. But which seeds should be used? Many scientists and environmentalists are speaking out in favour of seed from the same region as that in which the future grassland will lie. Ecologists from the Helmholtz Centre for Environmental Research (UFZ) in Halle (Saale), Germany, have carried out a joint study with colleagues from the universities of Tübingen and Münster, and TUM (Technische Universität München), to investigate the suitability of this approach. Two studies in the Journal of Applied Ecology have shown that using indigenous seed actually does bring benefits. For many years now, foresters have not just used any random seed when planting new trees. They have long known that not every European beech or Common oak tree is the same. In fact, every species has many variants which have adapted to suit the specific challenges of their environment. Some might, for example, withstand drought better than others, while others might survive harsh winters or thrive in poor soils. For this reason, German forestry has regulations that specify exactly which region the seed must come from, for a particular planting. "To date, there have been no similar regulations for grassland plants", said Dr. Walter Durka, a biologist working at the UFZ. Anyone wanting to create a wildflower meadow in their garden or plant a new grassland habitat as part of a nature conservation project will find a huge range of seed mixtures available for purchase. These will definitely come from native plant species, but might theoretically have been produced anywhere in the world. In 2007 and 2008 alone, Germany imported 13,000 tonnes of grass seed and 280 tonnes of herb seed. "It may be cheaper to buy this seed abroad", he explained, "but the plants may then have adapted to suit conditions somewhere like New Zealand, for example, and not German regions such as Bavaria or Brandenburg". For this reason, many ecologists are speaking out in favour of also using seed from locally grown grassland plants. Scientists from the University of Hanover have also already developed a concept in which Germany is divided up into 22 areas of origin, using different geographical criteria. These areas of origin are then grouped in eight production zones. Several companies are already offering seed whose areas of origin can be precisely traced. Demand for this kind of seed is likely to continue to rise in future. The reason is that, from 2020, only indigenous seed of this kind can be used in Germany for recultivating grasslands in open countryside. Until recently there has simply been insufficient data to provide a well-informed answer to this question. The extent of the actual genetic differences between members of the same species from different areas of origin was simply unknown. And that's without even mentioning whether such differences actually affect how the plants flourish. This is precisely the knowledge gap that the researchers at UFZ wanted to close. Working together with colleagues at TUM (Technische Universität München), and the universities in Tübingen and Münster, they investigated seven common grassland plants that came from eight of the 22 German areas of origin. "We found genetic differences between the regions for all the species", summed up Walter Durka. However, how big these genetic differences are depends on the biology of the particular plant. For example, grasses that are pollinated by the wind, and cannot fertilise themselves, exchange their genetic information over relatively large distances. For this reason, the researchers found the extremely common false oatgrass to have the smallest genetic difference between the regions. The opposite applied in the case of ragged robin. This species uses insects to distribute its pollen, sometimes even between flowers on the same plant. In addition, it is much rarer than false oatgrass. "This all leads to a low gene flow, which results in large genetic differences between populations", explained Walter Durka. In the case of some species such as white bedstraw, the researchers also discovered a definite trend: the genetic differences become ever greater, the further the areas of origin are apart, and the more their climates differ. According to Durka, this is a clear indicator that these plants have adapted to their regional conditions. They should therefore be more successful close to their origin than in other parts of Germany. The team tested whether this hypothesis is correct in a second study. To do so, the researchers sowed the seven species from the eight regions in Freising, Tübingen, Halle (Saale) and Münster, and observed how well they grew, and when they flowered. "In the case of many of the grassland species examined, it was indeed the case that plants that had the same regional origin grew better", reported Dr. Anna Bucharova and Prof. Oliver Bossdorf from the University of Tübingen. For example, on average, regional plants produced seven percent more biomass and ten percent more inflorescences than members of the same species that came from other regions of origin. Even the unusually warm temperatures in summer 2013, when the tests were carried out, had no effect on the test results. Critics of the regional seed concept often argue that it is not future-proof in a time of climate change: their argument is that, as temperatures increase, plants from the south are more likely to succeed than plants from the same region. However, the researchers found no indicators that this is the case: although temperatures in the experimental gardens in 2013 were 1.5 to two degrees above the average, calculated over many years, the plants from warmer regions had no advantage. This may be due to the fact that it is not only the temperature that is the decisive factor in whether growth is better or worse. The length of the days, or the composition of the microbial communities at the particular location, might also play an important role. If the regional plants are better adapted to suit such factors, then they can obviously also make use of their inherent relative strengths in warm years. Yet it was not only the plant itself that profited from its adaptation to regional conditions. The researchers also discovered that the individual variants also flower at different times. Brown knapweed of different origins flowered up to 17 days apart. In the case of white bedstraw the difference was as much as 23 days. "From an ecological point of view, that is a huge difference", said Anna Bucharova. It should also be remembered that many animal species, from the pollinators to the inhabitants of the flower heads to the seed eaters, operate on the time plan that is usual for the region. "Scientifically, there is a real danger that this entire ecosystem could get into difficulties if plants from a different region flowered at the wrong time", she said. This is yet another reason for fostering the use of seed originating from the same region. More information: Walter Durka et al. Genetic differentiation within multiple common grassland plants supports seed transfer zones for ecological restoration, Journal of Applied Ecology (2016). DOI: 10.1111/1365-2664.12636 Anna Bucharova et al. Genetic differentiation and regional adaptation among seed origins used for grassland restoration: lessons from a multi-species transplant experiment, Journal of Applied Ecology (2016). DOI: 10.1111/1365-2664.12645


News Article
Site: www.rdmag.com

​Biogas is an important energy source that plays a central role in the energy revolution. Unlike wind or solar energy, biogas can be produced around the clock. Could it soon perhaps even be produced to meet demand? A team of international scientists, including microbiologists from the Helmholtz Centre for Environmental Research (UFZ), scientists from Aarhus University and process engineers from the Deutsches Biomasseforschungszentrum (DBFZ), have been studying the feasibility of this kind of flexible biogas production. Among their findings, for example, is the discovery that biogas production can be controlled by altering the frequency at which the reactors are fed. If the intervals are longer, more biogas is produced, according to the researchers' paper in the Applied and Environmental Microbiology journal. Biogas production has long been a valuable technology, as the constant feed of organic raw materials such as energy crops, manure, sewage sludge, catch crops and plant residues helps produce energy around the clock. The ability to produce energy at a constant rate is a clear advantage over other renewable energy sources such as wind or solar energy, which depend on the wind or sun for production. As a result of this ability, Germany currently has around 8,000 biogas plants installed, with a total electricity output of approximately 4,500 megawatts. Around seven percent of the electricity generated in Germany now comes from biomass. It is hoped that even more electricity will be produced from this source in the future. Scientists from the UFZ, the University of Aarhus (Denmark) and the DBFZ succeeded in increasing the production of methane, the most valuable component of biogas, by up to 14 percent under laboratory conditions when the scientists added the substrate to the fermentation tank at intervals of between one and two days compared to the conventional interval of every two hours feeding. The results were astonishing: "Feeding the reactor less often results in greater energy yield", said Marcell Nikolausz, PhD, UFZ researcher at the Department of Environmental Microbiology and corresponding author of the study. The researchers fed two 15-litre reactors with distiller's dried grains with solubles (DDGS) under identical conditions for a total period of almost four months. DDGS is a by-product of bioethanol production using starchy grains. The researchers fed one reactor with DDGS every two hours. The other reactor was fed with the entire quantity once per day, in one experiment, and once every other day in a second experiment. The results were surprising. If the full quantity of biomass was fed into the fermentation tank just once a day, 14 percent more methane and 16 percent more total biogas is produced. If the tank was fed every two days, methane yield increased by 13 percent and biogas yield increased by 18 percent. One explanation for this could be that the greater variations in environmental conditions, particularly the fluctuating substrate concentration, increased the diversity of the microbial community, leading to more functional groups of bacteria. "This gives the micro-organisms more ways to degrade the substrate more efficiently", said microbiologist Nikolausz. He explained that this accelerates production and provides the micro-organisms with better conditions in which to process the biomass more efficiently, especially the components that are difficult to degrade. This flexible feeding management approach has no negative effect on the stability of the biogas production process. The researchers proved this by using T-RFLP profiles of the micro-organisms. This method can be used to verify the genetic fingerprint of the community of bacteria and methanogenic archaea that convert the organic material to biogas in the reactor. In case of the bacteria that convert the complex components of the biomass, such as cellulose, starch, lipids and proteins, into carbon dioxide, hydrogen and acetic acids, in several stages, the composition of these bacterial communities varies in the different feeding regimes. This is because the concentrations of ammonium nitrogen and hydrogen vary, as does the pH value. "The environment in the reactor is more dynamic when it is fed daily or every other day. This creates more functional niches, benefiting certain hydrolysing and acid-producing bacteria", said Nikolausz. In contrast, the community of methanogenic archaea, which in the final stage produce methane, water and carbon dioxide, remained stable. Regardless of how often the reactor was fed with biomass, the Methanosarcina genus, with a relative proportion of up to 83 percent of all methanogens, was consistently dominant followed by the genus Methanobacterium, which constituted up to 31 percent of all methanogens. "Both genera appear to adapt well to the changing conditions", Nikolausz explained. Research into flexible biogas production by employing feeding management is still in its infancy. The UFZ researchers plan to delve deeper into the results of the study. According to Nikolausz, the research results now need to be confirmed by trials in larger reactors. The use of other substrates is also an interesting subject. "We are keen to see whether we can also confirm that higher quantities of methane are produced when corn silage or sugar beets are used," said Nikolausz.


The workshop titled "Flying beauties" took place in August 2016, the second day of the Final LEGATO Meeting, at the Kinakin Primary school, Banaue Municipality, Ifugao Province, Philippines. If focused on butterflies and dragonflies and their roles in the surrounding natural and agricultural landscape. This workshop was the culmination of several weeks of active preparation together with the different groups of participants, and, in fact, only the set off of the Flying Beauties citizen science competition that will be open until the end of the year. Thirty students from two local schools and their teachers, alongside a group of senior citizens and tour guides, had the unique chance to take part in an event, where important project results presentation was combined with on-field data collection and testing of findings. Butterflies and dragonflies are not only attractive insects, but also in the spotlight of LEGATO research due to their relevance for building sustainable rice ecosystems. It comes as no surprise that these two animal groups were also central to LEGATO's citizen science day, where participants were given the simple yet exciting task to find and photograph featured species on field to then enter a photo contest. Children and adults alike were on the search for species selected by LEGATO scientists on the basis of their importance for rice ecosystems in the region, rarity and conservation status. The exercise combined in one task two key objectives of the project: raising the awareness of people for the beautiful nature around, getting them interested in learning more about it and motivate them to use modern technology to collect data in a playful way. After several hours on field armed with digital cameras and fresh knowledge on butterflies and dragonflies, the citizen science team came back with a great selection of photographed species. The exercise that took place as a part of LEGATO final meeting was just a first highlight for the Flying Beauties project which aims to showcase the benefits of citizen science, where all kind of people can contribute to biodiversity knowledge and get aware and learn about their local nature. "We saw some real enthusiasm and I am sure lots of the facts we explained about the different species and their importance for rice will stick with the children taking part," explains Norbert Hirneisen. "We are positive that we created genuine interest to science and its applicability in everyday life in the contestants. Additionally, the photographic evidence collected this day could be useful in further research!" "Real world impact of research findings can be secured by translating results and passing them on to the end users in an understandable and engaging way," comments project coordinator Prof. Josef Settele, UFZ. "Our event demonstrates how an entertaining approach and use of new technologies can engage citizens in data collecting and re-use of research findings in their everyday lives." Explore further: Sustainability of rice landscapes in South East Asia threatened


News Article
Site: phys.org

Marcell Nikolausz an his collegues discover that biogas production can be controlled by altering the frequency at which the reactors are fed. Credit: André Künzelmann/UFZ Biogas is an important energy source that plays a central role in the energy revolution. Unlike wind or solar energy, biogas can be produced around the clock. Could it soon perhaps even be produced to meet demand? A team of international scientists, including microbiologists from the Helmholtz Centre for Environmental Research (UFZ), scientists from Aarhus University and process engineers from the Deutsches Biomasseforschungszentrum (DBFZ), have been studying the feasibility of this kind of flexible biogas production. Among their findings, for example, is the discovery that biogas production can be controlled by altering the frequency at which the reactors are fed. If the intervals are longer, more biogas is produced, according to the researchers' paper in the Applied and Environmental Microbiology journal. Biogas production has long been a valuable technology, as the constant feed of organic raw materials such as energy crops, manure, sewage sludge, catch crops and plant residues helps produce energy around the clock. The ability to produce energy at a constant rate is a clear advantage over other renewable energy sources such as wind or solar energy, which depend on the wind or sun for production. As a result of this ability, Germany currently has around 8,000 biogas plants installed, with a total electricity output of approximately 4,500 megawatts. Around seven percent of the electricity generated in Germany now comes from biomass. It is hoped that even more electricity will be produced from this source in the future. Scientists from the UFZ, the University of Aarhus (Denmark) and the DBFZ succeeded in increasing the production of methane, the most valuable component of biogas, by up to 14 percent under laboratory conditions when the scientists added the substrate to the fermentation tank at intervals of between one and two days compared to the conventional interval of every two hours feeding. The results were astonishing: "Feeding the reactor less often results in greater energy yield", summarised Dr Marcell Nikolausz, UFZ researcher at the Department of Environmental Microbiology and corresponding author of the study. The researchers fed two 15-litre reactors with distiller's dried grains with solubles (DDGS) under identical conditions for a total period of almost four months. DDGS is a by-product of bioethanol production using starchy grains. The researchers fed one reactor with DDGS every two hours. The other reactor was fed with the entire quantity once per day, in one experiment, and once every other day in a second experiment. The results were surprising. If the full quantity of biomass was fed into the fermentation tank just once a day, 14 percent more methane and 16 percent more total biogas is produced. If the tank was fed every two days, methane yield increased by 13 percent and biogas yield increased by 18 percent. One explanation for this could be that the greater variations in environmental conditions, particularly the fluctuating substrate concentration, increased the diversity of the microbial community, leading to more functional groups of bacteria. "This gives the micro-organisms more ways to degrade the substrate more efficiently", said microbiologist Nikolausz. He explained that this accelerates production and provides the micro-organisms with better conditions in which to process the biomass more efficiently, especially the components that are difficult to degrade. This flexible feeding management approach has no negative effect on the stability of the biogas production process. The researchers proved this by using T-RFLP profiles of the micro-organisms. This method can be used to verify the genetic fingerprint of the community of bacteria and methanogenic archaea that convert the organic material to biogas in the reactor. In case of the bacteria that convert the complex components of the biomass, such as cellulose, starch, lipids and proteins, into carbon dioxide, hydrogen and acetic acids, in several stages, the composition of these bacterial communities varies in the different feeding regimes. This is because the concentrations of ammonium nitrogen and hydrogen vary, as does the pH value. "The environment in the reactor is more dynamic when it is fed daily or every other day. This creates more functional niches, benefiting certain hydrolysing and acid-producing bacteria", said Nikolausz. In contrast, the community of methanogenic archaea, which in the final stage produce methane, water and carbon dioxide, remained stable. Regardless of how often the reactor was fed with biomass, the Methanosarcina genus, with a relative proportion of up to 83 percent of all methanogens, was consistently dominant followed by the genus Methanobacterium, which constituted up to 31 percent of all methanogens. "Both genera appear to adapt well to the changing conditions", Nikolausz explained. Research into flexible biogas production by employing feeding management is still in its infancy. The UFZ researchers plan to delve deeper into the results of the study. According to Nikolausz, the research results now need to be confirmed by trials in larger reactors. The use of other substrates is also an interesting subject. "We are keen to see whether we can also confirm that higher quantities of methane are produced when corn silage or sugar beets are used," said Nikolausz. Explore further: More profitable biogas production by optimization of anaerobic waste digestion More information: Daniel Girma Mulat et al. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways, Applied and Environmental Microbiology (2016). DOI: 10.1128/AEM.02320-15

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