Peatland Degradation Reduces Microbial Richness and Alters Microbial Functions in an Australian Peatland

Peatland ecosystems cover only 3 % of the world’s land area, however they store one-third of the global soil carbon (C). Peatlands play a central role in global C cycling as they contain more organic C than any other terrestrial ecosystem. Microbial communities are the main drivers of C decomposition in peatlands, yet we have limited knowledge of their structure and function. We investigated the vertical stratification of prokaryote and fungal communities from Wellington Plains peatland in the Australian Alps. Within the peatland complex, bog peat was sampled from the intact peatland and dried peat from the degraded peatland along a vertical soil depth gradient (i.e., acrotelm, mesotelm and catotelm). We analysed the prokaryote and fungal community structure, predicted functional profiles of prokaryotes using PICRUSt and assigned soil fungal guilds using FUNGuild. We found that the structure and the function of prokaryotes was vertically stratified in the intact bog. Carbon, manganese, nitrogen, lead and sodium best explained the prokaryote composition. Prokaryote richness was significantly higher in the intact bog acrotelm compared to degraded bog acrotelm. Fungal composition remained similar across the soil depth gradient, however there was a considerable increase in saprotroph abundance and decrease in endophyte abundance along the vertical soil depth gradient. The abundance of saprotrophs and plant pathogens was two-fold higher in the degraded bog acrotelm. Manganese, nitrogen, electrical conductivity and water table level (cm) best explained the fungal composition. Our results demonstrate that both fungal and prokaryote communities are shaped by soil abiotic factors and peatland degradation reduces microbial richness and alters microbial functions. Thus, current and future changes to the environmental conditions in these peatlands may lead to altered microbial community structure and associated functions which may have implications for broader ecosystem function changes in peatlands.

Effect of elevated tropospheric ozone on soil carbon and nitrogen: A meta-analysis

Elevated tropospheric ozone concentration ([O3]) may substantially influence the belowground processes of the terrestrial ecosystem. Nevertheless, a comprehensive and quantitative understanding of the responses of soil C and N dynamics to elevated [O3] remains elusive. In this study, the results of 41 peer-reviewed studies were synthesized using meta-analytic techniques, to quantify the impact of O3 on ten variables associated with soil C and N, i.e., total C (TC, including soil organic C), total N (TN), dissolved organic C (DOC), ammonia N (NH4 +), nitrate N (NO3 -), microbial biomass C (MBC) and N (MBN), rates of nitrification (NTF) and denitrification (DNF), as well as C/N ratio. The results depicted that all these variables showed significant changes (P < 0.05) with [O3] increased by 27.6 ± 18.7 nL/L (mean ± SD), including decreases in TC, DOC, TN, NH4 +, MBC, MBN and NTF, and increases in C/N, NO3 - and DNF. The effect sizes of TN, NTF, and DNF were significantly correlated with O3 fumigation level and experimental duration (P < 0.05). Soil pH and climate were essential in analyses of O3 impacts on soil C and N. However, the responses of most variables to elevated [O3] were generally independent of O3 fumigation method, terrestrial ecosystem type, and additional [CO2] exposure. The altered soil C and N dynamics under elevated [O3] may reduce its C sink capacity, and change soil N availability thus impact plant growth and enhance soil N losses.

Total and bioavailable heavy metals in the soils of two adjacent forests

<p>The concentrations and comparisons of total and available metals Cd, Cr, Ni, Pb and the metalloid As were examined in two adjacent acid forest soils in Greece under oak and beech together with the dependency of their availability. It was found that the soil in the beech plot had higher concentrations of total elements with the exception of the litter layer (L) where most metals did not differ. It is probable that the parent material of the beech soil contained some metamorphic mafic material. The surface soils for both stands were moderately enriched with Pb, Cd and As, whereas for Cr and Ni the enrichment was minimal. The concentrations of available elements (extracted with DTPA) were higher in the beech soil. The availability of most metals was affected by the pH, the organic C, the ratio of C/N and the total concentration of the metals. Through a Principal Component Analysis (PCA) analysis, it was found that 63-75% of the concentrations variance of the available metals was explained. The percentages of available metals with regard to their total concentrations in soils were higher in the beech plot in the FH layer but in the mineral layers, they did not differ apart from Pb. The concentrations of the metals in the leaves of both species in three consecutive years did not differ with the exception of Cd, the concentration of which was higher in the beech leaves.</p>

Plant Growth Modifications Due to Coastal Embankments Affect Soil Bacterial and Archaeal Communities Over the Growing Season in Salt Marshes of Eastern China

Aims: Although the influences of coastal embankments on physicochemical soil properties and carbon (C) and nitrogen (N) cycling have been widely studied, the mechanisms of their effects on soil microbial ecologies remain poorly understood. Thus, the aim of this study was to investigate variations in the diversity and composition of soil bacterial and archaeal communities between natural and embanked saltmarshes, as well as the determinants that drive these variations.Methods: 16S rRNA gene sequence analysis was performed to assess the impacts of embankments on the bacterial and archaeal communities of native Suaeda salsa, Phragmites australis, and invasive Spartina alterniflora saltmarshes on the east coast of China.Results: Embankments were found to significantly decrease the microbial diversity of the S. alterniflora salt marsh, while they increased the OTU richness of the P. australis salt marsh. Embankments modified the compositions of soil bacterial and archaeal communities in both the S. alterniflora and P. australis salt marshes. However, variations in the microbial diversity, richness, and community compositions between the native and embanked S. salsa salt marshes were insignificant. Conclusions: These results were possibly because the embankment significantly altered soil nutrient substrate levels (e.g., soil organic C and N) by variations in plant residues and physiochemical soil properties in S. alterniflora and P. australis saltmarshes, whereas the embankment had no observable changes in the soil nutrient substrate and the plant residue in S. salsa saltmarsh. This study also elucidated the effects of coastal embankments on biogeochemical cycles, and highlighted their potential hazards to ecosystems.

Factors Affecting Productivity of Oil Palm (Elaeis guineensis Jacq.) at Various Afdelings in Bah Jambi Farm PT. Perkebunan Nusantara IV

North Sumatra Province, where the second-highest oil palm productivity in Indonesia, has successfully reached fresh fruit bunches (FFB) production of 5,775,631.82 tons in 2016. However, the level of oil palm productivity tends to be unstable and low. The purpose of this study was to identify and analyze factors influencing the level of oil palm productivity at the Bah Jambi Plantation PTPN IV, Simalungun Regency, North Sumatra Province. The method used in this study was the qualitative descriptive analysis method by collecting secondary data at research locations at 4 Afdeling Kebun Bah Jambi PT. Nusantara IV Plantation. The results of correlation and regression analysis showed that soil factor such as organic C, soil pH, cation exchange capacity and the availability of soil N, P, K and Mg is the most dominant factors in influencing the amount of oil palm productivity which have determination coefficient (R2) more than 90%. Meanwhile, climate factors such as evapotranspiration, duration of light exposure, wind speed and rainfall have the most role in influencing oil palm productivity which has a coefficient of determination (R2) of 95%, 94%, 88% and 33%.

Analysis of Soil Primary Macro Nutrient Status in Agricultural Land, Tabundung District, East Sumba Regency

Agricultural land is land that can affect agricultural productivity. Land, which is part of land resources, is the main component in the production of agricultural commodities. In supporting the productivity of agricultural commodities, there must be sufficient nutrients in the soil. Tabundung sub-regency is a producer of food crops, livestock and fisheries. As the main producer in the agricultural sector, the production of agricultural crops is not proportional to the total area of harvested land, meaning that the productivity of agricultural crops is not optimal if it is based on harvested area. The study was conducted in Tarimbang Village, Proud Watu and Tapil Regency of Tabundung. The method used in this research was survey technique and soil sampling was carried out in a composite manner. Soil samples were analyzed at the Nusa Cendana University Laboratory, Kupang. Primary data analyzed were elements of nitrogen (N), phosphorus (P), potassium (K), organic carbon (C), cation exchange capacity (CEC), and pH. The results showed that the overall nutrient status of N, P, and K were in the medium, high and very high categories, but there were some sample points that were in the low category for macronutrients N and P. While the concentrations of organic C, CEC and pH were overall generally in pretty good condition. This condition indicates that the research area provides sufficient nutrients for plant cultivation during the growth and yield of plants, but improvements are needed to overcome macronutrient deficiencies in several observation locations.