European Journal of Soil Biology最新文献

The distribution of earthworm ecological groups in urban areas is not well-known, despite their crucial role in delivering soil ecosystem services such as nutrient cycling and water drainage. Citizen science engages public audiences in the scientific research process and is an excellent tool for collecting biodiversity data in urban areas, where most of the UK population resides. However, a disadvantage is that differing levels of skill and engagement among participants can create statistical challenges. The Earthworm Watch citizen science project used 668 matched-pair surveys to estimate how the abundance and ecological diversity of earthworms respond to land management practices, and soil properties in UK urban habitats. A total of 5170 earthworms were counted during the project with a mean of 8 earthworms per soil pit - equivalent to a density of 198 earthworms per m². Soil moisture and texture were the largest drivers of total earthworm abundance, with habitat borderline statistically insignificant. Endogeic earthworms were found in 71 % of soil pits, epigeic in 62 % and anecic in 33 %. Fertiliser use also had a significant effect on total abundance, but only when organic fertiliser was used. Earthworm ecological groups demonstrated varied responses to habitat, with endogeic earthworms consistently the most abundant group, showing slight preferences for grasslands and vegetable beds. Anecic earthworms had the lowest abundance across all habitats but were more prevalent in grasslands and vegetable beds. Epigeic earthworms were most abundant beneath shrubs and hedges. These findings align with expected patterns of earthworm ecology, underscoring the potential of well-designed citizen science projects to yield valuable insights into urban earthworms and soil health.

Earthworm burrowing is essential for soil functioning in temperate climates. It is known that soil compaction hampers earthworm burrowing, but there is a lack of knowledge on how it affects the energy costs of earthworms. In the present study, we used respirometry and isothermal calorimetry to quantify earthworm respiration rates and heat dissipation in two endogeic species, Aporrectodea caliginosa and Aporrectodea tuberculata, in compacted and non-compacted soils. We put the measured respiration rates and heat dissipation in relation to the burrow volume and cast volume produced by the earthworms. We found that at higher compaction levels, respiration rates and dissipated heat increased for both studied species. The energy costs associated with burrowing were a significant fraction of the total energy costs. Our results indicate that energy costs per burrow volume increase due to compaction, and that the specific energy costs for burrowing (i.e., per gram earthworm) were lower for A. tuberculata than for A. caliginosa. Further studies are needed to confirm our results. We discuss the potential and current limitations of isothermal calorimetry as a method for direct quantification of energy costs of earthworms. There is a need for further studies that quantify how energy costs of burrowing are affected by various soil conditions, to better predict the implications of land use and soil management on soil processes and functions mediated by earthworm burrowing.

Silicon (Si) is an essential element for the growth and development of rice plants, playing a crucial role in their overall health and productivity. This study aimed to measure earthworm's impact on Si dynamics in northern Vietnam's paddy fields. The properties of earthworm casts from 23 different sites were compared to the surrounding topsoil. The results showed that the casts were enriched in biogenic silica (herein phytoliths) and plant-available Si (measured through acid acetic extraction, Si_AC) compared to the reference topsoil. Also, casts had a higher sand content, while their carbon content was similar to the reference soils. This suggests a possible preference for sand particles by earthworms (e.g., for grinding plant material within their gizzards) and/or the consumption of soil from another layer enriched in sand content. The influence of earthworms on Si dynamics was found to be dependent on the soil's environmental properties. In soils with low fertility (characterized by a higher proportion of sand and lower concentrations of C and oxides), earthworms increased the concentration of Si_AC. However, beyond a certain level, the effect of earthworms on Si availability became neutral. While this study highlights the critical role of earthworms in paddy fields, further research is needed to understand how earthworms enhance the concentration in Si_AC in the topsoil, and the consequences to rice growth and resistance to environmental hazards.

Climate warming can accelerate soil organic matter decomposition and stimulate soil CO₂ and N₂O emissions. However, long-term climate warming and land-use changes in relatively high-latitude regions on soil CO₂ and N₂O emissions remain largely unexplored, posing challenges to climate change research. Therefore, we conducted a long-term soil transplant experiment (8 years) across three relatively high-latitude northeastern regions in China to study the impacts of climate warming and land-use changes (from cropland to grassland) on soil CO₂ and N₂O emissions. As the temperature increased by 3 °C and 5 °C, the soil CO₂ emissions from cropland were reduced by 59.07% and 56.87%, respectively, and those from grassland were reduced by 17.11% and 10.62%, respectively. The experiment duration, soil C storage, soil microbial abundance and soil moisture may be the main factors that explain why warming did not stimulate soil CO₂ emissions. Soil N₂O emissions increased by 76.57% in cropland and 263.81% in grassland as the temperature increased by 5 °C. Higher soil CO₂ and N₂O emissions were observed in grassland compared to cropland. Warming promoted aboveground plant biomass and indirectly promoted soil N₂O emissions, particularly in grassland. The effects of long-term warming on soil CO₂ and N₂O emissions exhibited contrasting patterns, with CO₂ emissions in relatively high-latitude and cold regions showing sensitivity to climate warming. When taking strategies to enhance soil C sequestration, consideration should be given to whether these strategies will be offset by stimulating soil N₂O emissions, which is crucial for mitigating global warming. Overall, the impacts of long-term natural field warming and land-use changes on soil CO₂ and N₂O emissions and associated controls provide new insights for mitigating climate change.

Field studies in post-mining sites on epigeic invertebrate groups are scarce despite their importance in pedogenesis and ecosystem multifunctionality. This research investigated the diversity, abundance and succession of aboveground invertebrates in a rehabilitated Pb/Zn tailings chronosequence of 5, 20 and 35 years. The study also explored the trophic relationship of selected arthropods and characterized the nitrogen (N) cycle using stable isotope measurements. The abundance and species richness in most investigated groups and the dominance index Berger–Parker (BP) of aboveground invertebrates increased with rehabilitation age from 0.17 BP in early to 0.31 BP in late stage. Elemental and stable isotope ratio analysis showed that N and C soil content increased and the C/N ratio decreased with age, yet despite this increased N availability in the system, the maturing N-cycle used N efficiently. The lack of large N losses from the system despite substantial atmospheric deposition inputs was indicated by the fact that N isotope ratios (δ¹⁵N) in plants and animals became significantly more negative with rehabilitation age, −6.0 δ¹⁵N for plants, −5.0 δ¹⁵N for herbivores and 3.0 δ¹⁵N for carnivores. The length of the invertebrate food chain expanded by more than half a trophic level (2.7‰ δ¹⁵N) for top predator Coleoptera from early to late stage, probably reflecting more complex food webs including intra-guild predation in older communities. In conclusion, δ¹⁵N measurements in plants and animals provided novel insights into the N-cycle, accumulative N flows and the trophic position in post-mining sites. It is proposed that isotope ratio measurements could be used as easy-to-measure, integrating indicators of nutrient cycling and the soil food web complexity of rehabilitated mine tailings and similar soil ecosystems.

Distribution patterns of species diversity in high mountains have received considerable attention in scientific research and conservation efforts. However, our understanding of the corresponding altitudinal patterns of soil fauna across spatial scales, particularly on high-altitude plateaus, remains limited. To address this gap, we conducted a case study on Balang Mountain, located at the eastern margin of the Tibetan Plateau. Our focus was on soil nematodes within an altitudinal range of approximately 3000 to 4000 m. We collected climate, soil, and vegetation data to test multiple hypotheses, including the effects of energy, water availability, productivity, soil resource availability, and pH constraints on nematode communities. Dominance analysis and commonality analysis were employed to determine the relative support of these hypotheses in explaining nematode abundance, diversity, and composition. Beta-diversity, which links local alpha-diversity and regional gamma-diversity, was decomposed into distinct components to elucidate ecological processes along altitude and across diversity facets. Our findings revealed distinct yet significant altitudinal patterns in nematode abundance (concave-down), richness (monotonous decrease), and evenness (concave-up). Water and soil resource availability emerged as dominant factors influencing nematode abundance, while energy and pH played pivotal roles in determining nematode richness. Additionally, water and productivity were identified as the most significant drivers shaping nematode community composition. Furthermore, a significant influence of pH on gamma- and beta-diversities was observed, surpassing the impact of other predictors at a coarse level. Upon decomposing beta-diversities into different components, we discovered that taxa substitution (turnover) and individual substitution (balance-variation) were the primary contributors to community dissimilarity among altitudes, indicating strong effects of environmental sorting or spatial and historical constraints on soil nematode communities. These findings contribute to our understanding of the distribution patterns and processes of soil nematode communities along altitude in alpine ecosystems. Moreover, they offer valuable insights into soil biodiversity distribution and conservation in high-mountain environments.

The study aimed to evaluate the effects of P and K fertilization strategies with and without N-fertilization on soil quality and crop yields in integrated crop-livestock system (ICLS) in the Brazilian Cerrado. The treatments included various fertilization strategies, such as applying P and K during either the cropping phase (conventional fertilization) or the pasture phase (system fertilization), with or without N-fertilization during the pasture phase. Soil samples were collected two years after the experiment was initiated from the 0–10 cm layer, and soybean yields were determined at the end of the crop cycle. Soil carbon (C) stocks remained largely unaffected by the different fertilization strategies. However, soil nitrogen (N) stocks, as well as C and N within the microbial biomass, were lower when conventional fertilization and 0 kg ha⁻¹ of N were used in pastures compared to other treatments. Enzyme activity also decreased with conventional fertilization and 0 kg ha⁻¹ of N in pastures. Scores for Nutrient Cycling and Nutrient Storage were higher with 100 kg ha⁻¹ compared to 0 kg ha⁻¹ of N in the case of conventional fertilization, marking an increase of 22% and 18% for Nutrient Cycling and Nutrient Storage, respectively. For soil function associated with Nutrient Supply, there was no difference between the treatments. Within the 0 kg ha⁻¹ of N group, system fertilization was 12% and 24% higher compared to conventional fertilization. The soil quality index (SQI_FERTBIO) was higher with 100 kg ha⁻¹ (0.83) compared to 0 kg ha⁻¹ of N (0.77), showing an 8% increase. Soybean yield was 3% higher with system fertilization and 7% higher with 100 kg ha⁻¹ of N, compared to conventional fertilization with 0 kg ha⁻¹ of N. In conclusion, even in the short term, adopting a system fertilization strategy and applying N-fertilization in pastures benefits soybean yields in ICLS under no-till.

No-tillage (NT) and no-tillage systems (NTS) are widely used conservation agriculture practices in Brazil, and in the state of Paraná, nearly 80% of annual crops are cultivated using these methods. Compared with NT, NTS sites permanently include: minimum soil disturbance, soil cover (straw and living vegetation) and crop rotation and diversification with cover crops. These practices often increase earthworm populations, that can be used to indicate soil health. Herein, we review soil health classification of NT sites, and the species found in Paraná state. We compiled information from 130 sites with NT or NTS, located in 29 counties, of which 93 had biomass and 91 had species richness data, aiming to compare NT with NTS sites, and the effect of the age of these practices on earthworm populations. Overall, 29 earthworm species were recorded, of which 17 were native, including many new to science. Mean abundance and biomass in NT + NTS were 104 ind m⁻² and 2.5 g m⁻², respectively, and richness 2.5 species per site. Abundance was significantly higher in NT than NTS in the initial phase of adoption, and both abundance and biomass decreased with increasing age of NT. Earthworm abundance and species richness were positively correlated with clayey soils and phosphorus content, while higher biomass was associated with soil carbon content and pH. A new classification system was proposed, with the categories poor (<50 ind. m⁻², 1 species), moderate (≥50 to <100 ind m⁻², 2 species), good (≥100 to <150 ind m⁻², 3 species), very good (≥150 to 200 ind m⁻², 4 species) and excellent (≥200 ind m⁻², ≥5 species) soil health, using earthworm abundance and species richness, respectively. Most of the sites sampled showed poor or moderate soil health, with few displaying very good or excellent health, indicating the need for improved management practices, in order to promote earthworm populations and their potential benefits to soil fertility and plant production.

Low-molecular-weight organic carbon (LMWOC) from root exudate influences soil organic carbon cycling via priming of microbial activity. However, the mechanisms underlying the uptake and utilization of specific exudates by microorganisms in soils remain unclear. To address this gap in knowledge, a one-month ¹³C (0.1 mg C﹒g soil) tracer incubation study was conducted to investigate the fate of the most abundant root exudate groups (using ¹³C-labeled glucose, acetic acid, and oxalic acid) in paddy vs. upland soil. After 2 days of incubation, the microbial substrate use efficiency (SUE) was >80% in paddy soil, which was approximately 1.9, 2.9, and 1.3 times that in uplands with glucose, acetic acid, and oxalic acid addition, respectively. The SUE in paddy soil with glucose or acetic acid addition was always higher than that in uplands over time (P < 0.05). In both soils, the SUE of glucose was 1–4 times that of carboxylic acids (P < 0.05). The recovery of ¹³C-labeled total phospholipid fatty acids (PLFAs) in paddy soils was 1.5–2 times that in uplands (P < 0.05). In both soils, bacteria preferred to utilize glucose and acetic acid to synthesize cellular components. Throughout the incubation period, bacteria dominated over fungi in terms of LMWOC consumption. Gram-positive and -negative bacteria were dominant in upland and paddy soils, respectively. From days 11–30, the contribution of fungi and actinomycetes to LMWOC utilization began to appear. Temperature positively regulated ¹³C distribution in microbial groups (P < 0.05), and increased dissolved organic carbon in upland soil accelerated microbial SUE. The results of this study clarify microbial effects on the high soil carbon sequestration capacity of paddy soil as compared with upland in subtropical areas.