Dynamics of Rare Earths and associated major and trace elements during Douglas-fir (Pseudotsuga menziesii) and European beech (Fagus sylvatica L.) litter degradation

Given the diverse physico-chemical properties of elements, we hypothesize that their incoherent distribution across the leaf tissues, combined with the distinct resistance to degradation that each tissue exhibits, leads to distinct turnover rates between elements. Moreover, litter layers of different ages produce diverse chemical signatures in solution during the wet degradation. To verify our hypothesis, Na, K, Mg, Mn, Ca, Pb, Al and Fe were analysed together with the Rare Earth Elements (REE) in the solid fractions and in the respective leachates of fresh leaves and different humus layers of two forested soils developed under Pseudotsuga menziesii and Fagus sylvatica L. trees. The results from the leaching experiment were also compared to the in situ REE composition of the soil solutions to clarify the impact that the litter degradation processes may have on soil solution chemical compositions. Our results clearly show that REE, Al, Fe and Pb were preferentially retained in the solid litter material, in comparison to the other cations, and that their concentrations increased over time during the litter degradation. Accordingly, different litter fractions produced different yields of elements and REE patterns in the leachates, indicating that the tree species and the age of the litter play a role in the chemical release during the degradation. In particular, the evolution of the REE patterns according to the age of the litter layers allowed us to deliver new findings on REE fractionation and mobilization during litter degradation. In particular, the LaN/YbN ratio highlights differences in litter degradation intensity between both tree species, which was not shown with major cations. We finally showed the primary control effect that litter degradation can have on the REE composition of the soil solution, which presents a positive Ce anomaly associated with the dissolution and/or transportation of Ce-enriched MnO2 particles accumulated onto the surface of the old litter due to white fungi activity. Similar MREE and HREE enrichments were also found in the leachates and the soil solution, probably due to their higher affinity to the organic acids, which represent the primary products from the organic matter degradation.

Effect of Biofertilizers Application on Soil Biodiversity and Litter Degradation in a Commercial Apricot Orchard

The aim of the present experiment was to determine if the supply of biofertilizers could differently stimulate the native microbiota, thus determining different patterns of organic material decomposition processes. The microbial composition of soil and litter was investigated by next generation sequencing using a metabarcoding approach. The chemical structure of the decomposing litterbags was investigated through the TG-DTA analysis and NIR spectroscopy. The study was conducted in an apricot orchard in Italy, and two different type of biofertilizers (AMF and Trichoderma spp.) were compared to unfertilized control over one year. Bacteria and fungi in soil, 162 days from litter deposition, evidenced differentiated clusters for control and both biofertilizers; on the other hand, only fungal composition of litterbags was modified as a consequence of Trichoderma spp. supply; no effect was observed in the bacterial community of litterbags. NIR and TG-DTA analysis evidenced a significant change over time of the chemical composition of litterbags with a faster degradation as a consequence of Trichoderma spp. supply testified by a higher degradation coefficient (1.9) than control (1.6) and AMF (1.7). The supply of biofertilizers partially modified the bacteria community of soil, while Trichoderma spp. Influenced the fungal community of the litter. Moreover, Trichoderma spp. Evidenced a faster and higher degradation of litter than AMF-biofertilizers, laying the foundation for an efficient use in orchard.

Culturable bacteria from an Alpine coniferous forest site: biodegradation potential of organic polymers and pollutants

The potential of the culturable bacterial community from an Alpine coniferous forest site for the degradation of organic polymers and pollutants at low (5 °C) and moderate (20 °C) temperatures was evaluated. The majority of the 68 strains belonged to the phylum Proteobacteria (77%). Other strains were related to Bacteroidetes (12%), Alphaproteobacteria (4%), Actinobacteria (3%), and Firmicutes (3%). The strains were grouped into 42 different OTUs. The highest bacterial diversity was found within the phylum Bacteroidetes. All strains, except one, could grow at temperatures from 5 to 25 °C. The production of enzyme activities involved in the degradation of organic polymers present in plant litter (carboxymethyl cellulose, microgranular cellulose, xylan, polygalacturonic acid) was almost comparable at 5 °C (68%) and 20 °C (63%). Utilizers of lignin compounds (lignosulfonic acid, lignin alkali) as sole carbon source were found to a higher extent at 20 °C (57%) than at 5 °C (24%), but the relative fractions among positively tested strains utilizing these compounds were almost identical at the two temperatures. Similar results were noted for utilizers of organic pollutants (n-hexadecane, diesel oil, phenol, glyphosate) as sole carbon source. More than two-thirds showed constitutively expressed catechol-1,2-dioxygenase activity both at 5 °C (74%) and 20 °C (66%). Complete phenol (2.5 mmol/L) degradation by strain Paraburkholderia aromaticivorans AR20-38 was demonstrated at 0–30 °C, amounts up to 7.5 mmol/L phenol were fully degraded at 10–30 °C. These results are useful to better understand the effect of changing temperatures on microorganisms involved in litter degradation and nutrient turnover in Alpine forest soils.

Pengelolaan ekosistem mangrove untuk ruang terbuka hijau sebagai mitigasi gas rumah kaca di kawasan Sungai Tallo Kota Makassar

One of the ecological functions of mangroves ecosystem is to store carbon. Yet, on the other hand it also has the potential to cause greenhouse gas emissions through litter degradation even though its value is lower compared to the absorption value. Based on these two facts, mangrove management as a Green Open Space in the Tallo river area of ​​Makassar City needs to consider involving the participation of the community and the government as stakeholders. The research was conducted by desk work, literature study and respondent interviews regarding perceptions and participation in mangrove management. The results showed that the total uptake of mangrove carbon in the Tallo river in Makassar city was 351.02 tons CO2/ha, oxygen supply 255.29 O2-equivalent/ha, and the potential for global warming was 252.41 mg/ m2/hour consisting of 194, 33 mg/m2/hour of CO2 gas, 15.76 mg/m2/hour of CH4 gas, and 42.33 mg/m2/hour of N2O gas. The results of community perception and participation analysis show that around 89% of the community strongly agreed and supported the government in the effort to manage mangroves as a green open space. Based on this, the ecosystem in the Tallo river is very suitable to be managed for green open space as fresh air supplier and CO2 adsorber as well as a noise reduction from vehicle or industrial engines in Makassar city.

Effect of Detritus Manipulation on Different Organic Matter Decompositions in Temperate Deciduous Forest Soils

Soil organic matter supply is mainly derived from plant litter. The early stages of litter degradation is a very dynamic process. Thus, its study is important for understanding litter degradation and the control factors of different biomes and ecosystems. In the frame of the Síkfőkút DIRT (Detritus Input and Removal Treatments) Project, the effect of organic matter treatment was studied on the rate of decomposition of organic matter by applying different kinds of organic materials (leaf and wood litter, green and rooibos tea material, and cellulose cotton wool). During long-term experiments, we intended to investigate how the different organic matter manipulations changed by the soil microbial community and how it affects the degradation of different quality organic matter in the soil. The important main purpose of the research was to investigate litter degradation and its main regulators, contributing to both current and future climate scenarios. According to our results, in the case of litter-doubling treatments, we experienced a greater loss of organic matter compared to the weight of the litter bags placed in the soil of organic matter-withdrawal treatments. Furthermore, based on our results, we found that the decomposition rate is influenced by litter quality (leaf and cellulose wool) that is to be decomposed and by the applied litter treatments depending on the time allowed for decomposition. A drier climate by slowing down the degradation processes and by increasing the proportion of recalcitrant molecules in the detritus may increase the turnover time, which may lead to an increase in soil organic carbon (SOC).

Contrasting Effects of Sediment Microbial Fuel Cells (SMFCs) on the Degradation of Macrophyte Litter in Sediments from Different Areas of a Shallow Eutrophic Lake

Eutrophication is one of the major ecological problems of our era. It accelerates the growth of aquatic plant and algae, eventually leading to ecological deterioration. Based on a 700-day lab experiment, this paper investigated the contrasting effects of sediment microbial fuel cells (SMFCs) on the removal of macrophyte litter in a macrophyte-dominated area and an algae-dominated area from two bay areas of a shallow eutrophic lake. The results revealed that the removal efficiencies of total organic carbon increased by 14.4% in the macrophyte-dominated area and 7.8% in the algae-dominated area. Moreover, it was found that sediment samples from the macrophyte-dominated area became more humified and had a higher electricity generation compared to the sediment samples from the algae-dominated area. Pyrosequencing analysis further determined that SMFC promoted more aromatic compound-degrading bacteria growth in sediments from the macrophyte-dominated area than from the algae-dominated area. Our study demonstrated that SMFC could enhance organic matter degradation, especially plant litter degradation, but this influence showed different from sediment sources. Thus, SMFC is capable of providing a useful strategy for delaying the terrestrialization of lakes areas suffering from eutrophication.

Comparative Studies on the Effect of Adjuvants with Urea to Reduce the Overwintering Inoculum of Venturia inaequalis

A 2-year study on the use of organic and conventional adjuvants alone, or mixed with urea, was conducted for management of overwintering inoculum of the apple scab pathogen, Venturia inaequalis. Select adjuvants (LI 700, Bond Max, Latron B-1956, and Organic Wet Betty [OWB]) have the potential to hasten urea-driven leaf litter decomposition and reduce V. inaequalis overwintering inoculum comparable to urea, and that one organic surfactant could perform the same level of leaf decomposition as urea. Combinations of adjuvants with urea significantly improved leaf litter degradation compared with urea alone, concomitant with reducing the number of pseudothecia present and pseudothecium fertility. We demonstrate that the combination of urea with Bond Max or OWB reduced pseudothecia fertility and ascospore production to less than 5% in the remaining pseudothecia, a significantly greater reduction than with urea alone. These results suggest that conventional growers combine urea with Bond Max or OWB to more effectively reduce overwintering inoculum, and that the adjuvant OWB can provide organic growers with comparable performance to urea used in conventional orchards for improved sanitation.