Ecosystem Water Use Efficiency in the Three-North Region of China Based on Long-Term Satellite Data

Water use efficiency (WUE), given by the ratio between organic matter production and water consumption, could be considered as a very important ecological indicator for assessing vegetation system growth conditions by combining organic matter production and water consumption. It is especially important for regional vegetation sustainable management by creating enough organic matter with restricted water supply. Furthermore, proper analysis of WUE is vital for the evaluation and future plans of ecological restoration projects in ecologically fragile regions such as the Three-North region of China. In this study, ecosystem WUE across the Three-North region of China from 2001 to 2017 was obtained, and the variation trends and major influencing factors were also analyzed. The results demonstrated that (1) the average WUE across the Three-North region of China is 0.7376 g∙C∙m−2∙mm−1 with an annual increase of 0.002 g∙C∙m−2∙mm−1∙y−1; (2) the spatiotemporal variation trends of WUE are similar to those of gross primary production (GPP); and (3) in the southeastern parts of the Three-North region, the vegetation conditions are better with sustainable improvements, while in Xinjiang Province, the sustainable degradation areas are widely spread. The results of this research reveal large spatial heterogeneity of WUE, with high WUE mainly in the southeastern region with sufficient precipitation and afforestation programs. For those areas far away from this region, WUE is not satisfactory, suggesting that, for a sustainable vegetation growth, it is important to consider the water supply to maintain suitable vegetation cover. Furthermore, the results of this research are important for future ecological restoration and sustainable management of environment.

Baltic Earth Assessment Report on the biogeochemistry of the Baltic Sea

Location, specific topography and hydrographic setting together with climate change and strong anthropogenic pressure are the main factors shaping the biogeochemical functioning and thus also the ecological status of the Baltic Sea. The recent decades have brought significant changes in the Baltic Sea. First, the rising nutrient loads from land in the second half of the 20th century led to eutrophication and spreading of hypoxic and anoxic areas, for which permanent stratification of the water column and limited ventilation of deep water layers made favourable conditions. Since the 1980s the nutrient loads to the Baltic Sea have been continuously decreasing. This, however, has so far not resulted in significant improvements in oxygen availability in the deep regions, which has revealed a slow response time of the system to the reduction of the land-derived nutrient loads. Responsible for that is the low burial efficiency of phosphorus at anoxic conditions and its remobilization from sediments when conditions change from oxic to anoxic. This results in a stoichiometric excess of phosphorus available for organic matter production, which promotes the growth of N2-fixing cyanobacteria and in turn supports eutrophication. This assessment reviews the available and published knowledge on the biogeochemical functioning of the Baltic Sea. In its content, the paper covers the aspects related to changes in carbon, nitrogen and phosphorus (C, N and P) external loads, their transformations in the coastal zone, changes in organic matter production (eutrophication) and remineralization (oxygen availability), and the role of sediments in burial and turnover of C, N and P. In addition to that, this paper focuses also on changes in the marine CO2 system, structure and functioning of the microbial community and the role of contaminants for biogeochemical processes. This comprehensive assessment allowed also for identifying knowledge gaps and future research needs in the field of marine biogeochemistry in the Baltic Sea.

High local nutrient input influence on oligotrophic phytoplankton production and lipid biogeochemistry

<p>Marine phytoplankton are crucial for ecosystem function and responsible for almost half of world’s primary production. In order to grow and reproduce phytoplankton need sufficient amount of macro and micro nutrients. Nutrient concentrations are changeable in different water mases and dependable on different natural and anthropogenic sources such as terrestrial water inputs, recycling by sloppy feeding, remineralization with bacteria and atmospheric deposition. High nutrient input to oligotrophic regions raises phytoplankton biomass that leads to higher organic matter production and heterotrophs` development.  Anthropogenic nutrient inputs are considered as the main cause of coastal eutrophication. Marine lipids, dominantly produced by phytoplankton, are good biogeochemical traces of organic matter origin and processing in marine environment and phytoplankton adaptation to environmental perturbations. They are important for multiple cell mechanisms functioning.</p><p>The goal of this research was to investigate the influence of a point source of nutrients on organic matter production and lipid composition as a consequence of phytoplankton acclimation to different nutrient loads. We sampled at two geographically close stations in the Krka River Estuary mouth, oligo- to mesotrophic Martinska station and station in vicinity of the town of Šibenik that is under high anthropogenic influence. Samples were taken from three depths (above, on and below halocline) and in four different seasons covering annual cycle. Lipid classes were characterized by thin–layer chromatography–flame ionization detection. Data are supported by hydrographic, dissolved organic carbon and particulate organic carbon parameters. We will discuss the changes of organic matter accumulation and estuarine lipid biogeochemistry caused by human activity.</p><p> </p><p>Acknowledgement</p><p>This research was financed by the Croatian Science Foundation project BiREADI (IP-2018-01-3105).</p>

Geographical variability of bacterial communities of cryoconite holes of Andean glaciers

Cryoconite holes, ponds full of melting water with a sediment on the bottom, are hotspot of biodiversity of glacier surface. They host a metabolically active bacterial community that is involved in different dynamics concerning glacier ecosystems. Indeed, they are responsible of organic matter production and with other microorganisms establish a real microecosystem. Cryoconite holes have been described in different areas of the world (e.g., Arctic, Antarctic, Alps, Himalaya), and with this study we will provide the first description of bacterial communities of cryoconite holes of the Andes in South America. We collected samples on three high elevation glaciers of the Andes (Iver, Iver East and Morado glaciers) and two Patagonian glaciers located at sea level (Exploradores glacier and Perito Moreno). Results show that the most abundant orders are Burkholderiales, Cytophagales, Sphingobacteriales, Actinomycetales, Pseudomonadales, Rhodospiarillales, Rhizobiales, Sphingomonadales and Bacteroidales, which have been reported on glaciers of other areas of the world, Bacterial communities change from one glacier to another and both water pH and O2 concentration affect bacterial communities composition.

Localization of the organic matter production and degradation in two different estuaries

Physical and chemical processes related to primary production of the estuaries of two rivers with different water regime are considered with special attention to their spatial and seasonal variability. Both production and degradation of the organic matter are quantitatively evaluated on the data of non-conservative variation of dissolved inorganic phosphorus concentration in the process of the river water dilution. Contribution of recycling to the phosphorus balance and the estuarine waters productivity is estimated. The organic matter degradation prevailed in the internal part of both estuaries, but its production dominated in their external parts, with a tendency of production lowering and degradation strengthening from spring to autumn. Utilization of the re-mineralized phosphorus in the external estuaries increased their potential productivity by 20-50%, provided by the terrigenous flux with the river water.

What is respiration - response to glucose addition, presence of plant roots and differences across biomes

<p>Respiration is likely the most often measured process in soil ecology. It is used as a general measurement of soil activity, and physiologically related to microbial maintenance requirements, growth, and soil organic matter production via biochemical efficiency and CUE.</p><p>Genomic tools are increasingly used in soil ecology for measurement of community composition, and functional analysis of communities, and when combined with stable isotopes, can be used to infer activities, either of the whole community or of individual taxa. However, relating genomic or gene-expressed functions to whole ecosystem processes, such as respiration, remains a conceptual and practical problem.</p><p>We analyzed the biochemical processes related to respiration and determine how, during a short soil incubation experiment in the presence of glucose, these processes change. Furthermore, we will show how gene and transcript abundances of respiratory processes vary across more than 4000 soil and rhizosphere samples in forests and grasslands and other biomes.  </p><p>Results illustrate the treasure trove of biochemical information available to us in the form of metagenomes and metatranscriptomes.</p>

Applying the δ18O Parameter for Evaluating of Organic Matter Production-destruction Processes in the Barents Sea

The authors present the determination method of nutrient’s background concentration in the seawater. In this work, as a basis for the proposed method, we use a three-component system [1-6, 10, 11, 12, 13] for mixing water masses in the Barents Sea based on the parameter δ18О. Simple mixing of purely Atlantic water masses and purely river water masses, as well as ice formation and melting processes, were taken into account. The authors suppose that the background concentration is a concentration that changes only as a result of water transformation, such as melting and freezing. The authors consider background concentration of phosphates, nitrates and silicates for the Barents Sea calculated from previously collected data. The difference between measured and background concentrations indicates the production or destruction process of organic matters. If the results are positive - there is destruction; if negative, there is - production. The data for δ18О, salinity, phosphates, nitrates, and silicates that were used in this study were taken from an open-source database published on the NASA website and in our own collection. Samples were taken in the summer.

The Effect of Variety and Harvesting Time of Sorghum Planted in Stylosanthes Pasture on Growth, Production and Prussic Acid Content

This research was aimed to determine the growth, production and prussic acid content of sorghum variety that planted on stylosanthes pasture with different harvesting time. This research was done using split-plot design with three replications which sorghum variety (brown midrib resistance (BMR) and Super-2) as the main plot and harvesting time (6, 8 and 10 weeks) as the sub plot. The sorghum seeds were germinated for 12 days before planted on the 30 days stylosanthes pasture which was planted with planting space 25 x 25 cm. Sorghum was planted with planting space 75 x 25 cm. The variables observed were plants height, dry and organic matter production and prussic acid. Data obtained were analyzed statistically using analysis of variance and significantly different between means were tested with Duncan's New Multiple Range Test (DMRT). Sorghum BMR had plant height, dry and organic matter production higher (P<0.05) than Super-2. Prussic acid content of BMR was lower (P<0.05) than Super-2. The older harvesting time increase (P<0.05) plant height, dry matter and organic production, but reduced (P<0.05) prussic acid content from 727.34 mg/kg to 241.71 mg/kg. Based on the results it can be concluded that the oldest harvesting time (10 weeks) produced the highest dry and organic matter, and reduce prussic acid content. Sorghum BMR is more productive and grew faster than Super-2. Sorghum BMR that harvested in 10-week shows the best in growth and productivity also had lower prussic acid content.