1,446 publications from this institution
The topic of the absence of CO2 increase in the 40ties is very relevant and still unclear.-The suggested 2 hypotheses: WWII and warm climate in this period are good and very interesting.-The Authors prepared a lot of materials reconstructing land cover and land use in the 40ties in the Former Soviet Union (FSU).There is not a lot of official (and probably not a lot of unofficial) materials about this time.Therefore, every additional data and opening of the data for broad communities are strong contribution to the retrospection and window to this difficult time.
Background Soil and vegetation have a direct impact on the process and direction of plant community succession, and determine the structure, function, and productivity of ecosystems. However, little is known about the synergistic influence of soil physicochemical properties and vegetation features on vegetation restoration. The aim of this study was to investigate the co-evolution of soil physicochemical properties and vegetation features in the process of vegetation restoration, and to distinguish the primary and secondary relationships between soil and vegetation in their collaborative effects on promoting vegetation restoration in a subtropical area of China. Methods Soil samples were collected to 40 cm in four distinct plant communities along a restoration gradient from herb (4–5 years), to shrub (11–12 years), to Pinus massoniana coniferous and broadleaved mixed forest (45–46 years), and to evergreen broadleaved forest (old growth forest). Measurements were taken of the soil physicochemical properties and Shannon–Wiener index (SD), diameter at breast height (DBH), height ( H ), and biomass. Principal component analysis, linear function analysis, and variation partitioning analysis were then performed to prioritize the relative importance of the leading factors affecting vegetation restoration. Results Soil physicochemical properties and vegetation features showed a significant trend of improvement across the vegetation restoration gradient, reflected mainly in the high response rates of soil organic carbon (SOC) (140.76%), total nitrogen (TN) (222.48%), total phosphorus (TP) (59.54%), alkaline hydrolysis nitrogen (AN) (544.65%), available phosphorus (AP) (53.28%), species diversity (86.3%), biomass (2906.52%), DBH (128.11%), and H (596.97%). The soil properties (pH, SOC, TN, AN, and TP) and vegetation features (biomass, DBH, and H ) had a clear co-evolutionary relationship over the course of restoration. The synergistic interaction between soil properties and vegetation features had the greatest effect on biomass (55.55%–72.37%), and the soil properties contributed secondarily (3.30%–31.44%). The main impact factors of biomass varied with the restoration periods. Conclusions In the process of vegetation restoration, soil and vegetation promoted each other. Vegetation restoration was the cumulative result of changes in soil fertility and vegetation features.
Estimation of the amount of root exudates and simultaneous identification of their composition in non‐sterile soil is a challenging objective in rhizosphere research. We coupled 3 methods: (1) labeling of corn in 14 CO 2 atmosphere to separate root‐derived and soil‐derived organic substances in the rhizosphere, (2) a previously developed leaching method to collect rhizodeposits, and (3) pyrolysis field ionization mass spectrometry (Py‐FIMS) to investigate the molecular‐chemical composition of rhizodeposits. Eluted rhizodeposits accounted for 2.8 % (Loam) and 0.97 % (nutrient solution in quartz sand) of recovered 14 C and showed clear differences in composition between the growth substrates. The 14 CO 2 evolved mostly by root respiration accounted for 3.5–4.0 % without significant differences according to growth substrate or diurnal dynamics. Principal component analysis of the Py‐FI mass spectra of leachates showed a clear diurnal dynamics of the amount and the composition of corn rhizodeposits collected during day‐time and night‐time. Differences originated mostly from signals assigned to carbohydrates, sterols, and peptides. This approach is recommended for forthcoming studies of rhizodeposition in different soil substrates, crops grown, and time‐series of exudate sampling.
Input of available carbon and/or mineral fertilisation can accelerate mineralisation of soil organic matter i.e. priming effect. However, studies to priming effects in andic soils are absent despite their unique physicochemical and biological properties. Nutrients and 14C labelled glucose were added to Andosols of Mt. Kilimanjaro from six ecosystems: (1) savannah (2) maize fields (3) lower montane forest (4) coffee plantation (5) grasslands and (6) Chagga homegardens. Carbon-dioxide production was measured for 60 days. Maximal and minimal mineralisation rates immediately after glucose additions were observed in lower montane forest with N + P (9.1% ± 0.83 d −1) and in savannah with N (0.9% ± 0.17 d −1), respectively. Land use significantly influenced glucose induced priming effect measured as additional CO2 compared to unfertilised soil. Variations of the priming effect in land use without fertilisation are attributed to differences in microbial biomass content. Depending on land use, nutrient addition increased or decreased glucose induced priming effect. Maximal and minimal priming effect were observed in grassland soils (0.171 mg C-CO2 g−1 soil) with P and in soils under maize fields (0.009 mg C-CO2 g−1) fertilized with N, respectively. Microorganisms in Chagga homegarden soils incorporated the highest glucose percentage (6.47% ± 1.16), which was 3 times higher compared to grassland soils (2.18% ± 0.39). 50-60% of the 14C input was retained in bulk soil. Land use and fertilisation (N and P) affected priming in Andosols. Andosols occurring at Mt. Kilimanjaro, especially those under the Chagga homegardens shows great potential for soil C sequestration.
Recently, there has been growing interest in the spatial distribution of microbial activity in soil; however, methods for analysis of spatial distribution of microbial activity and for localization of hotspots of enzyme activity in soil are limited. Here were present an in situ zymography technique for localization and quantification of enzyme activities in soil by means of thin gels with embedded substrates. After incubation, the substrate remaining in the gel is colored and quantified using calibration curves and digital image analysis. So far, zymography has mostly been used to localize enzymatic activity in electrophoresis gels and in tissue sections. In this study we developed a zymography technique for analysis of the two-dimensional distribution of enzyme activities in soil. The technique was applied to map and quantify protease and amylase activity in the rhizosphere of lupine (Lupinus polyphyllus) grown in rhizoboxes. Highest activities, of up to 46 ng mm−2 of the soil surface h−1 for the protease and of up to 0.90 μg mm−2 h−1 for the amylase were found in close association with roots. Since zymography is an in situ method that does not require destruction of soil structure, it likely pictures enzyme activities more realistically than standard enzyme assays. In conclusion, soil in situ zymography offers a promising tool for mapping distributions of enzyme activities in soils in a work- and cost-efficient way.
In this concept paper, we propose a new view on soil organic matter (SOM) formation: microorganisms use most of the organics entering the soil as energy rather than as a source of carbon (C), while SOM accumulates as a residual by-product because the microbial energy investment in its decomposition exceeds the energy gain. During the initial stages of decomposition, the nominal oxidation state of C (NOSC) in remaining litter decreases, and the energy content increases. This reflects the rapid mineralization of available compounds with positive and neutral NOSC (carboxylic acids, sugars, some amino acids). Consequently, the NOSC of the remaining compounds drops to -0.3 units, and the oxidation rate decreases due to the residual relative accumulation of aromatic and aliphatic compounds (which are hydrolized later) and entombment of the necromass. Ultimately, incompletely decomposed plant residues will have 1%-2.5% more energy per C unit than the initial litter. The linear decrease in energy density of a broad range of organic substances by 106 kJ mol-1 C per NOSC unit upon oxidation is supported by experimental data on litter decomposition. Preferential recycling of energy-rich reduced (lipids, aromatics, certain amino acids, amino sugars) and the microbial degradation of oxidized compounds (carboxylic acids) also energetically enrich SOM. Despite the high energy content, the availability of energy stored in SOM is lower than in litter. This explains why SOM is not fully mineralized (thermodynamically unfavorable), especially in the absence of plant C to provide new energy (e.g., in bare soil). Energy from litter activates decomposers to mine nutrients stored in SOM (the main ecological function of priming effects) because the nutrient content in SOM is 2-5 times higher than that of litter. This results in only 0.4%-5% year-1 of litter-derived C being sequestered in SOM, whereas SOM stores 1%-10% year-1 of the total litter-derived energy. Thus, the energy captured by photosynthesis is the main reason why microorganisms utilize organic matter, whereby SOM is merely a residual by-product of nutrient storage and a mediator of energy fluxes.
