Joint toxicity of three plant protection products to <Emphasis Type="Italic">Triticum aestivum</Emphasis> (L.) and <Emphasis Type="Italic">Brassica rapa</Emphasis> (L.)

Purpose  

Few studies have been conducted to evaluate the effects of mixtures of chemicals in terrestrial environment. Thus, it seems important to evaluate if the combined application of pesticides currently used in agricultural fields may pose a risk to terrestrial plants.     

Elevated UV-B radiation increased the decomposition of <Emphasis Type="BoldItalic">Cinnamomum camphora</Emphasis> and <Emphasis Type="BoldItalic">Cyclobalanopsis glauca</Emphasis> leaf litter in subtropical China

Purpose  

Ultraviolet-B (UV-B) radiation reaching the earth's surface has been increasing due to ozone depletion and can profoundly influence litter decomposition and nutrient cycling in terrestrial ecosystems. The role of UV-B radiation in litter decomposition in humid environments is poorly understood; we thus investigated the effect of UV-B radiation on litter decomposition and nitrogen (N) release in a humid subtropical ecosystem in China.     

A liquid chromatographic/mass spectrometric method to evaluate <Superscript>13</Superscript>C and <Superscript>15</Superscript>N incorporation into soil amino acids

Purpose  

Amino acids are highly associated with biogeochemical cycling and represent an important potential source and sink of carbon (C) and nitrogen (N) in terrestrial ecosystems. Tracing the isotope dynamics of amino acids can improve the understanding of the origin and transformation of amino acids in soil matrix at process-levels; hence, the liquid chromatographic/mass spectrometric (LC/MS) method to evaluate ¹³C or ¹⁵N enrichment in amino acids is necessary to be established.     

Impacts of anthropic pressures on soil phosphorus availability,concentration, and phosphorus forms in sediments in a Southern Brazilian watershed

Purpose  

The transfer of soil sediments and phosphorus from terrestrial to aquatic systems is a common process in agricultural lands. The aims of this paper are to quantify the soil phosphorus availability and to characterize phosphorus forms in soil sediments as contaminant agents of waters as a function of anthropic pressures.     

Temporal changes in abundance and composition of ammonia-oxidizing bacterial and archaeal communities in a drained peat soil in relation to N<Subscript>2</Subscript>O emissions

Purpose  

Boreal peat soils comprise about 3% of the terrestrial environments, and when drained, they become sources of the greenhouse gas nitrous oxide (N₂O). Ammonia oxidation can result in N₂O emissions, either directly or by fuelling denitrification, but we know little about the ecology of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in peat soils. Our aim was to determine temporal alterations in abundance and composition of these communities in a drained and forested peat soil in relation to N₂O emissions and ammonia oxidation activity.     

Silica content in soil solution and its relation with phytolith weathering and silica biogeochemical cycle in Typical Argiudolls of the Pampean Plain,Argentina—a preliminary study

Purpose  

Little is known on the silica biogeochemical cycle in terrestrial environments. The aim of this work is to assess phytolith’s role on the biogeochemical cycle of Si in Typical Argiudolls under different vegetation of the Pampean Plain, Argentina.     

Bioaccumulation studies with <Emphasis Type="Italic">Eisenia fetida</Emphasis> using an established degradation test system

Background  

Earthworms are considered as an appropriate test system to assess the bioaccumulation potential of substances in the terrestrial environment. For regulatory purposes test methods were developed and incorporated in the validation process. A test design that is particularly suited for testing ¹⁴C-labelled substances will be described here. This design was adapted from an established degradation test system for bioaccumulation tests with earthworms in soil. The antibiotic sulfadiazine was used as test substance in this study. Due to the biological activity and the widespread entering into soil by manure application, veterinary medicines have become the target of ecotoxicological risk assessment. A German research group provided the soil samples mixed with liquid pig manure, which contained the ¹⁴C-labelled test substance after having passed through the gut of animals. This exposure pathway reflects the real environmental conditions. Therefore, sulfadiazine was tested even though a significant bioaccumulation potential was not expected to be detected owing to its chemical properties.     

How do persistent organic pollutants be coupled with biogeochemical cycles of carbon and nutrients in terrestrial ecosystems under global climate change?

Purpose  

Global climate change (GCC), especially global warming, has affected the material cycling (e.g., carbon, nutrients, and organic chemicals) and the energy flows of terrestrial ecosystems. Persistent organic pollutants (POPs) were regarded as anthropogenic organic carbon (OC) source, and be coupled with the natural carbon (C) and nutrient biogeochemical cycling in ecosystems. The objective of this work was to review the current literature and explore potential coupling processes and mechanisms between POPs and biogeochemical cycles of C and nutrients in terrestrial ecosystems induced by global warming.     

Reducing CH<Subscript>4</Subscript> and CO<Subscript>2</Subscript> emissions from waterlogged paddy soil with biochar

Purpose  

A potential means to diminish increasing levels of CO₂ in the atmosphere is the use of pyrolysis to convert biomass into biochar, which stabilizes the carbon (C) that is then applied to soil. Before biochar can be used on a large scale, especially in agricultural soils, its effects on the soil system need to be assessed. This is especially important in rice paddy soils that release large amounts of greenhouse gases to the atmosphere.     

Relationship between soil microbial biomass determined by SIR and PLFA analysis in floodplain soils

Purpose  

Although the challenge of linking pedology and hydrology has been identified recently, the microbial diversity in floodplain soils has been studied little in comparison to terrestrial soils. In terrestrial soils, the relationship between soil microbial biomass (SMB) determined by substrate-induced respiration (SIR) and phospholipid fatty acids (PLFA) was examined in several studies. Floodplain soils reveal substantially different properties; they are exposed to drastic changes in water regime from flooded to dry conditions. The relation between SMB determined by SIR and PLFA has, up to the present, not been adequately proved in floodplain soils. Thus, this study was conducted to elucidate the relationship between SMB determined with both methods in a set of floodplain soils of eleven study sites from three study areas along the Elbe River (Germany).     

A phototrophy-driven microbial food web in a rice soil

Purpose  

Light is a major driver of primary productivity in most ecosystems on Earth. Phototrophic microorganisms harvest light to synthesize organic biomass for sustaining the global energy and carbon flow. However, the bottom-up model of phototrophic microorganisms as primary production and food source for higher trophic levels remains unclear in the terrestrial environment.     

Amino acid and peptide dynamics in horticultural soils under conventional and organic management strategies

Purpose  

Free amino acids (FAAs) and peptides, and dissolved organic nitrogen (DON) comprise key pools in terrestrial soil carbon (C) and nitrogen (N) cycles. A comparative study of organic and conventional arable farming systems was conducted in Shanghai, China to determine the influence of management practices on characterization of AA and peptide dynamics.     

Effects of anthropogenic silt on aquatic macroinvertebrates and abiotic variables in streams in the Brazilian Amazon

Purpose  

While environmental risks associated with petroleum extraction such as oil spills or leaks are relatively well known, little attention has been given to the impacts of silt. The increase in petroleum exploitation in Amazonia has resulted in sediment input to aquatic systems, with impacts on their biodiversity. Here we use a combination of field measurements and statistical analyses to evaluate the impacts of anthropogenic silt derived from the construction of roads, borrow pits, and wells during the terrestrial development of gas and oil, on macroinvertebrate communities in streams of the Urucu Petroleum Province in the Central Brazilian Amazon.     

Nitrogen loading levels affect abundance and composition of soil ammonia oxidizing prokaryotes in semiarid temperate grassland

Purpose  

Global nitrogen deposition has profound impact on the terrestrial ecosystem including the semiarid temperate grassland, causing vegetation community shifts and soil acidification. Little is known regarding the effect of nitrogen (N) deposition on the belowground microbial communities. This study aimed to examine the response of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to added N in semiarid temperate grassland.     

Endocrine disruption in a terrestrial isopod under exposure to bisphenol A and vinclozolin

Background, aim, and scope  

In the past decade there has been an increasing awareness about the possible consequences of human and wildlife exposure to endocrine disrupting compounds (EDCs). Bisphenol A (BPA) and vinclozolin (Vz) are EDCs which impacts on vertebrates have been largely investigated. Nevertheless, research on invertebrate effects, especially on soil organisms, are still largely under-represented. This work aims to extend the limited ecotoxicological datasets available and to provide tools to assess the effects of EDCs on the terrestrial species, using Porcellio scaber (Crustacea: Isopoda) as a model organism.     

Soil fungal communities differ in native mixed forest and adjacent <Emphasis Type="Italic">Araucaria cunninghamii</Emphasis> plantations in subtropical Australia

Purpose  

Commercial monoculture plantations of the native Australian Araucaria cunninghamii are common in subtropical and tropical Queensland and are generally established following clearing of native mixed forest. The consequences of such forest conversion for soil fungal communities, however, have not been assessed in detail.     

Effects of vegetation restoration and slope positions on soil aggregation and soil carbon accumulation on heavily eroded tropical land of Southern China

Background aim and scope  

Soil organic carbon (SOC) accumulation is strongly affected by soil erosion and deposition that differ at slope positions of a watershed. However, studies on the effects of topography on soil aggregation and SOC dynamics, especially after the implementation of vegetation restoration, are rare. Poorly understood mechanisms and a lack of quantification for the suite of ecological benefits brought by the impacts of topography after planting further obstructed our understanding of terrestrial ecosystem carbon (C) sequestration. The purposes of this study are to (1) quantify the impacts of vegetation restoration on size and stability of soil aggregates and the sequestration of C in soil and (2) to address the impacts of various slope locations on aggregates and SOC distribution.     

Leaf litter-colonizing microbiota: supplementary food source or indicator of food quality for Porcellio scaber (Isopoda: Oniscidea)?

Different explanations have been proposed for why terrestrial isopods prefer, and gain from, feeding on microbially inoculated food materials. In the present study, no-choice feeding experiments are used to test three contrasting, but not mutually exclusive, hypotheses. (1) The digestion and nutritional utilization of microbial cells enhance the nutritive value of leaf litter; (2) extracellular digestive enzymes of microbial origin promote digestion of leaf litter; (3) leaf litter-colonizing microbiota serve as indicators for easily digestible leaf litter of high nutritive value. Predictions derived from these hypotheses are compared with the results of a study with experimentally manipulated leaf litter, serving as food sources for the common woodlouse Porcellio scaber. Leaf litter-colonizing microbiota increased consumption of leaf litter by isopods and contributed somewhat to biomass gain of isopods, but not to the assimilation of ingested food. Thus, the present results coincide with predictions derived from hypothesis (3) suggesting that leaf litter-colonizing microbiota stimulate consumption by indicating high food quality. Their positive effects on assimilation and growth, however, are context-specific, being stronger in case of high-quality food than in case of low-quality food.     

Can terrestrial isopods (Isopoda: Oniscidea) make use of biodegradable plastics?

Biodegradable plastics more and more replace conventional plastics, because they are considered environmentally friendly. Soil macro-invertebrates have been demonstrated to consume some of these biodegradable plastics, but studies usually do not go beyond notice of consumption and possible short-term ecotoxicological effects on organisms. This study uses the terrestrial isopod Porcellio scaber as a soil detritivore model and three biodegradable plastics (starch-, cellulose- and poly(3-hydroxybutyrate) (PHB)-based films) to evaluate both the contribution of isopods to the disintegration of biodegradable plastics and the effects of plastic-feeding on isopod ecology. Consumption rate of starch-based plastic was similar to that of leaf litter (mainly beech) and on average higher than those of the other two plastic types. Digestibility, however, was highest for cellulose-based plastic. HPLC results show that isopods break down starch-based plastic into maltose and glucose, and cellulose-based plastic into cellobiose. No glucose was present in feces of isopods having fed cellulose-based plastic, either for inability of breaking down cellobiose into glucose, or due to a rapid uptake of the glucose by isopods. Growth rates were negative, but not significantly different from zero, for all food sources; cellulose-based plastic caused the highest biomass loss to isopods. Toughness of starch-based plastic diminished over time when litter and/or isopods were present. Cellulose-based plastic increased in toughness over the disintegration experiment, possibly affecting its consumption by isopods. Overall, isopods increased the disintegration rates of starch- and cellulose-based plastics, but no PHB film was consumed, and its disintegration rate was low. We conclude that starch-based plastic is comparable to a natural low-quality food source (e.g., beech litter), and isopods would probably consume starch- and cellulose-based plastics in the field.     

Temporal dynamics of iron-rich, tropical soil organic carbon pools after land-use change from forest to sugarcane

Background, aim, and scope  

Land-use change can significantly influence carbon (C) storage and fluxes in terrestrial ecosystems. Soil–plant systems can act as sinks or sources of atmospheric CO₂ depending on formation and decomposition rates of soil organic matter. Therefore, changes in tropical soil C pools could have significant impacts on the global C cycle. This study aims to evaluate the impacts of long-term sugarcane cultivation on soil aggregation and organic matter, and to quantify temporal dynamics of soil organic matter in cultivated sugarcane plantation soils previously under a tropical natural secondary forest.