Forest defoliator outbreaks alter nutrient cycling in northern waters

Insect defoliators alter biogeochemical cycles from land into receiving waters by consuming terrestrial biomass and releasing biolabile frass. Here, we related insect outbreaks to water chemistry across 12 boreal lake catchments over 32-years. We report, on average, 27% lower dissolved organic carbon (DOC) and 112% higher dissolved inorganic nitrogen (DIN) concentrations in lake waters when defoliators covered entire catchments and reduced leaf area. DOC reductions reached 32% when deciduous stands dominated. Within-year changes in DOC from insect outbreaks exceeded 86% of between-year trends across a larger dataset of 266 boreal and north temperate lakes from 1990 to 2016. Similarly, within-year increases in DIN from insect outbreaks exceeded local, between-year changes in DIN by 12-times, on average. As insect defoliator outbreaks occur at least every 5 years across a wider 439,661 km2 boreal ecozone of Ontario, we suggest they are an underappreciated driver of biogeochemical cycles in forest catchments of this region.

Drought Monitoring over West Africa Based on an Ecohydrological Simulation (2003–2018)

In Africa, droughts are causing significant damage to human health and the economy. In West Africa, a severe decline in food production due to agricultural droughts has been reported in recent years. In this study, we simulated ecohydrological variables using the Coupled Land and Vegetation Data Assimilation System, which can effectively evaluate the hydrological water cycle and provide a dynamic evaluation of terrestrial biomass. Using ecohydrological variables (e.g., soil moisture content, leaf area index and vegetation water content) as a drought indicator, we analyzed agricultural droughts in the Sahel-inland region of West Africa during 2003–2018. Results revealed reasonable agreement between the simulated values and the pearl millet yield, and produced a successful quantification of severe droughts in the Sahel-inland region.

Mobile forms of carbon in trees: metabolism and transport

Plants constitute 80% of the biomass on earth, and almost two thirds of this biomass is found in wood. Wood formation is a carbon demanding process and relies on carbon transport from photosynthetic tissues. Thus, understanding the transport process is of major interest for understanding terrestrial biomass formation. Here we review the molecules and mechanisms used to transport and allocate carbon in trees. Sucrose is the major form in which carbon is transported, found in the phloem sap of all so far investigated tree species. However, in several tree species sucrose is accompanied by other molecules, notably polyols and the raffinose family of oligosaccharides. We describe the molecules that constitute each of these transport groups, and their distribution across different tree species. Further, we detail the metabolic reactions for their synthesis, the mechanisms by which trees load and unload these compounds in and out of the vascular system, and how they are radially transported in the trunk and finally catabolized during wood formation. We also address a particular carbon recirculation process between phloem and xylem that occurs in trees during the annual cycle of growth and dormancy. A search of possible evolutionary drivers behind the diversity of C carrying molecules in trees reveals no consistent differences in carbon transport mechanisms between angiosperm and gymnosperm trees. Furthermore, the distribution of C forms across species suggests that climate related environmental factors will not either explain the diversity of carbon transport forms. However, the consideration of C transport mechanisms in relation to tree—rhizosphere coevolution deserves further attention. To conclude the review, we identify possible future lines of research in this field.

Productivity of giant micancantus and soil fertility status for fertilizer application

Miscanthus giant is a tall perennial herbaceous plant with a well-developed root system, which is used for biofuel production. The aim of the study was to establish the effect of gi-ant miscanthus in the first year of growing season on the state of soil organic matter, removal and balance of nutrients and biological productivity of crops for fertilization. A four-year survey of the condition of miscanthus plantations was conducted at ‘Veselo Podilska’ research and breeding station during 2016‒2019 in the forest-steppe zone of Ukraine. Indicators of biomass productivity of giant miscanthus and the state of fertility of the grant for fertilizer application in the area of the left-bank of the Forest-Steppe of Ukraine for the production of solid biofuels are characterized. In the first year of the growing season, giant miscanthus produces more organic matter in the root system than in its terrestrial biomass ‒ 2.5 and 1.6 tons of dry matter/ha, respectively. It was found that foliar fertilization with microfertilizers significantly increased the yield of terrestrial biomass of giant miscanthus in the background of mineral fertilizers. The highest biological yield of ground mass of giant miscanthus was achieved with the introduction of N60P60K60 and two foliar fertilization with microfertilizer Vympel-K, 0.5 l/ha: yield of terrestrial biomass ‒ 3.1 tons of dry matter/ha with the advantage of control without fertilizers ‒ 1.5 tons/ha. In the first year of cultivation miscanthus giant uses a small amount of nutrients from the soil: nitrogen ‒ 20.4‒33.8 kg/ha, phosphorus ‒ 3‒5.3 kg/ha, potassium ‒ 6.1‒12.4 kg/ha . The application of N30P30K30 ferti-lizers was sufficient to form a balanced and expanded balance of nutrients in the soil. The appli-cation of mineral fertilizers did not affect the dynamics of organic matter in typical chernozem. Growing giant miscanthus in the first year of the growing season ensured the stability of the or-ganic matter content in the soil at the level of 4.04‒4.11%. At the same time, the content of mobile phosphorus at the end of the growing season decreased by 17‒18 mg/kg, potassium ‒ by 13‒43 mg/kg of soil. Reducing the content of mobile forms of phosphorus and potassium in the soil at the end of the growing season leads to efficient use of plant nutrients, chemical transformation of phosphorus into insoluble compounds and non-exchange adsorption of potassium ions by the soil complex in the biocenosis of miscanthus.

Computational modelling of cambium activity provides a regulatory framework for simulating radial plant growth

Precise organization of growing structures is a fundamental problem in developmental biology. In plants, radial growth is mediated by the cambium, a stem cell niche continuously producing wood (xylem) and bast (phloem) in a strictly bidirectional manner. While this process contributes large parts to terrestrial biomass, cambium dynamics eludes direct experimental access due to obstacles in live cell imaging. Here, we present a cell-based computational model visualizing cambium activity and integrating the function of central cambium regulators. Performing iterative comparisons of plant and model anatomies, we conclude that an intercellular signaling module consisting of the receptor-like kinase PXY and its ligand CLE41 constitutes a minimal framework sufficient for instructing tissue organization. Employing genetically encoded markers for different cambium domains in backgrounds with altered PXY/CLE41 activity, we furthermore propose that the module is part of a larger regulatory circuit using the phloem as a morphogenetic center. Our model highlights the importance of intercellular communication along the radial sequence of tissues within the cambium area and shows that a limited number of factors is sufficient to create a stable bidirectional tissue production.

Terrestrial Vegetation Drives Methane Production in the Sediments of two German Reservoirs

Inland waters and reservoirs in particular are significant sources of methane to the atmosphere. However, little information is available on the extent to which organic carbon from terrestrial vegetation or from internal photosynthesis fuels the methane production. This limits our ability to constrain methane emissions efficiently. We studied the isotopic composition (13C, 14C) of pelagic and sedimentary carbon sources in two small German reservoirs. The methane was enriched by radiocarbon with isotopic ranges (∆14C 5‰ to 31‰) near to fresh terrestrial organic carbon (OC, 17‰ to 26‰). In contrast, potential source OC produced by internal photosynthesis was characterized by negative ∆14C values (−30‰ and −25‰) as derived from signatures of inorganic carbon in the reservoirs. The particulate OC in stream supplies (terrestrial OC) was also 14C depleted in almost all cases, but highly variable in ∆14C (−131‰ to 42‰). Although the import of terrestrial OC was lower than the amount of OC produced by reservoir-internal photosynthesis, we conclude that the methane production was predominantly fuelled by catchment vegetation. The utilized terrestrial OC was of contemporary origin, fixed within years to decades before sampling and supplemented with reservoir-internal or aged terrestrial OC. Our results indicate that terrestrial biomass is an important driver of methane production in reservoirs receiving significant imports of terrestrial OC.

Successful Approaches for a Red Seaweed Biorefinery

Macroalgae have been commercially exploited as food and for the production of phycocolloids, but they also contain compounds with potential in pharmaceutical, nutraceutical, cosmetic, chemical and energetic applications. The biorefinery concept applied to seaweed facilitates the extraction of different constituents ensuring full utilization of resources and generating few residues through a succession of steps. Seaweed biorefineries are less advanced than those based on terrestrial biomass and the design of efficient processes requires further study. This review presents practical successful examples to obtain two or more commercially valuable components from red seaweeds. The selected processes consist on cascading stages of both conventional and alternative techniques to illustrate different possible valorization strategies.

Characterization and Analysis of Malaysian Macroalgae Biomass as Potential Feedstock for Bio-Oil Production

The potential of Caulerpa lentillifera, Gracilaria coronopifolia and Chaetomorpha linum, as biomass feedstock was investigated in this study. It was concluded that seaweed is more suitable for bio-based products synthesis, i.e., bioplastic and bio-lubricants, instead of biofuels due to its relatively low calorific value (~12 MJ/kg). Since seaweed has high moisture content (~80%), hydrothermal liquefaction is recommended, and its efficiency can be further enhanced through microwave technology. Besides, it is found that the thermal degradation of seaweed was best described with the reaction order of 1. The kinetic results also indicated that seaweed consists of lower activation energy (<30 kJ/mol) in comparison with terrestrial biomass (50–170 kJ/mol). Hence, seaweed has a high potential to be used as biomass feedstock, particularly Chaetomorpha linum, as it has no conflict with other interests. Lastly, acetic-acid pre-treatment was suggested to be an optional process in order to increase the algal conversion efficiency as it can reduce up to 25% of ash content.