Search Results (426)

This study investigates the seasonal dynamics of energy balance, evapotranspiration (ET), and Net Ecosystem Production (NEP) in the Dengkou desert ecosystem of Inner Mongolia, China. Using eddy covariance and meteorological data from 2019 to 2022, the research focuses on understanding how these processes interact in one of the world’s most water-limited environments. This arid research area received an average of 109.35 mm per annum precipitation over the studied period, classifying the region as a typical arid ecosystem. Seasonal patterns were observed in daily air temperature, with extremes ranging from −20.6 °C to 29.6 °C. Temporal variations in sensible heat flux (H), latent heat flux (LE), and net radiation (Rn) peaked during summer season. The average ground heat flux (G) was mostly positive throughout the observation period, indicating heat transmission from atmosphere to soil, but showed negative values during the winter season. The energy balance ratio for the studied period was in the range of 0.61 to 0.80, indicating challenges in achieving energy closure and ecological shifts. ET exhibited two annual peaks influenced by vegetation growth and climate change, with annual ET exceeding annual precipitation, except in 2021. Net ecosystem production (NEP) from 2019 to 2020 revealed that the Dengkou desert were a net source of carbon, indicating the carbon loss from the ecosystem. In 2021, the Dengkou ecosystem shifted to become a net carbon sink, effectively sequestrating carbon. However, this was sharply reversed in 2022, resulting in a significant net release of carbon. The study findings highlight the complex interactions between energy balance components, ET, and NEP in desert ecosystems, providing insights into sustainable water management and carbon neutrality strategies in arid regions under climate change effect. Full article

Invasive plant species pose an increasing threat to mangroves globally. This study assessed the impact of Paspalum vaginatum invasion on carbon loss and early recovery following four years of restoration in a mangrove forest with Rhizophora racemosa in Benin. Organic carbon was quantified in the total biomass, including both aboveground and belowground components, as well as in the soil to a depth of −50 cm. In addition, soil gas fluxes of CO₂, CH₄, and N₂O were measured. Three sites were evaluated: a conserved mangrove, a site degraded by P. vaginatum, and the same site post-restoration via hydrological rehabilitation and reforestation. Invasion significantly reduced carbon storage, especially in soil, due to lower biomass, incorporation of low C/N ratio organic residues, and compaction. Restoration recovered 7.8% of the total biomass carbon compared to the conserved mangrove site, although soil organic carbon did not rise significantly in the short term. However, improvements in deep soil C/N ratios (15–30 and 30–50 cm) suggest enhanced soil organic matter recalcitrance linked to R. racemosa reforestation. Soil CO₂ emissions dropped by 60% at the restored site, underscoring restoration’s potential to mitigate early carbon loss. These results highlight the need to control invasive species and suggest that restoration can generate additional social benefits. Full article

The DNDC-Rice model effectively simulates yield and greenhouse gas emissions within a paddy system, while its performance under upland conditions remains unclear. Using data from a long-term cover crop experiment (fallow [FA] vs. rye [RY]) in a soybean field, this study validated the DNDC-Rice model’s performance in simulating soil dynamics, crop growth, and C-N cycling processes in upland systems through various indicators, including soil temperature, water-filled pore space (WFPS), soybean biomass and yield, CO₂ and N₂O fluxes, and soil organic carbon (SOC). Based on simulated results, the underestimation of cumulative N₂O flux (25.6% in FA and 5.1% in RY) was attributed to both underestimated WFPS and the algorithm’s limitations in simulating N₂O emission pulses. Overestimated soybean growth increased respiration, leading to the overestimation of CO₂ flux. Although the model captured trends in SOC stock, the simulated annual values differed from observations (−9.9% to +10.1%), potentially due to sampling errors. These findings indicate that the DNDC-Rice model requires improvements in its N cycling algorithm and crop growth sub-models to improve predictions for upland systems. This study provides validation evidence for applying DNDC-Rice to upland systems and offers direction for improving model simulation in paddy-upland rotation systems, thereby enhancing its applicability in such contexts. Full article

Excessive chemical fertilizers degrade soil and increase greenhouse gas (GHG) emissions. Organic substitution of nitrogen fertilizers is recognized as a sustainable agricultural-management practice, yet its dual role in carbon sequestration and emissions renders the net GHG balance (NGHGB) uncertain. To assess the GHG mitigation potential of organic substitution strategies, this study analyzed GHG fluxes, soil organic carbon (SOC) dynamics, indirect GHG emissions, and Net Primary Productivity (NPP) based on a long-term field positioning experiment initiated in 2016. Six fertilizer regimes were systematically compared: no fertilizer control (CK); only phosphorus and potassium fertilizer (PK); total chemical fertilizer (NPK); 1/3 chemical N substituted with sheep manure (OF1); dual substitution protocol with 1/6 chemical N substituted by sheep manure and 1/6 substituted by straw-derived N (OF2); complete chemical N substitution with sheep manure (OF3). The results showed that OF1 and OF2 maintained crop yields similar to those under NPK, whereas OF3 reduced yield by over 10%; relative to NPK, OF1, OF2, and OF3 significantly increased SOC sequestration rates by 50.70–149.20%, reduced CH₄ uptake by 7.9–70.63%, increased CO₂ emissions by 1.4–23.9%, decreased N₂O fluxes by 3.6–56.2%, and mitigated indirect GHG emissions from farm inputs by 24.02–63.95%. The NGHGB was highest under OF1, 9.44–23.99% greater than under NPK. These findings demonstrate that partial organic substitution increased carbon sequestration, maintained crop yields, whereas high substitution rates increase the risk of carbon emissions. The study results indicate that substituting 1/3 of chemical nitrogen with sheep manure in maize cropping systems represents an effective fertilizer management approach to simultaneously balance productivity and ecological sustainability. Full article

This study examined the short-term effects of nitrogen (N) and phosphorus (P) addition on soil N₂O flux and organic carbon content in the lakeshore zone of an arid inland lake, Daihai. Treatments included control (N0P0), N addition (N1P0), P addition (N0P1), and NP co-addition (N1P1). Using the static chamber method and lab analyses, we measured soil N₂O flux and organic carbon content at different growth stages. Results showed that, in the early growing season, short-term N and P addition had no significant effect on soil N₂O flux, with all treatments acting as N₂O sources. However, N and NP treatments significantly increased soil organic carbon (SOC) storage, improving carbon sequestration benefits by 72.7% to 98.1%. During the peak growing season, N and NP treatments significantly enhanced soil N₂O emissions, while NP treatment further increased SOC storage, the carbon sequestration benefits of all treatments ranging from 49.0% to 56.5%. At the late growing season, N and P addition had no significant impact on soil N₂O flux or organic carbon storage, with all sites acting as N₂O sinks and SOC storage showing no significant change across treatments (carbon sequestration benefits ranged from 0.3% to 38.5%). The study highlights that the response of soil N₂O flux to short-term N and P addition varies at different growth stages, while overall, N and P addition promotes soil carbon sequestration throughout the growing season in the lakeshore zone. Full article

Reclaiming coastal wetlands for agricultural purposes has led to intensified farming activities, which are anticipated to affect greenhouse gas (GHG) flux processes within coastal wetland ecosystems. However, how greenhouse gas exchanges respond to variations in agricultural reclamation activities across different years remains uncertain. To address this knowledge gap, this study characterized dynamic exchanges within the soil–plant–atmosphere continuum by employing continuous monitoring across four representative coastal wetland soil–vegetation systems in Jiangsu, China. The results show the carbon dioxide (CO₂) and nitrous oxide (N₂O) flux exchanges between the system and the atmosphere and soil–vegetation carbon pools, which revealed the drivers of carbon dynamics in the coastal wetland system. The four study sites, converted from coastal wetlands to agricultural lands at different times (years), generally act as CO₂ sinks and N₂O sources. Higher levels of CO₂ sequestration occur as the age of reclamation rises. In terms of time scale, crops lands were found to be CO₂ sinks during the growing period but became CO₂ sources during the crop fallow period. Although the temporal trend of the N₂O flux was generally smooth, reclaimed farmlands acted as net sources of N₂O, particularly during the crop-growing period. The RDA and PLS-PM models illustrate that soil salinity, acidity, and hydrothermal conditions were the key drivers affecting the magnitude of the GHG flux exchanges under reclamation. This study demonstrates that GHG emissions from reclaimed wetlands can be effectively regulated through science-based land management, calling for prioritized attention to post-development practices rather than blanket restrictions on coastal exploitation. Full article

Climate change aggravates the frequency of extreme rainfall events, resulting in carbon (C) loss. For the special climate of the highlands, cultivating the land underneath orchards increases C reservation. Systematic research on the impact of extreme rainfall on soil organic carbon compositions and (dissolved organic carbon) DOC leaching is limited, especially regarding the response to different cropping patterns underneath orchards, requiring a deeper understanding. The results showed that the DOC-leaching fluxes for the cropping patterns under rainstorms and heavy rainstorms were in the order Dactylis glomerata L. monocropping (13.5, 4.4 kg/hm²) > Medicago sativa L. monocropping (11.2, 3.8 kg/hm²) ≥ D. glomerata. + M. sativa. (10.4, 3.6 kg/hm²). The DOC-leaching fluxes during heavy rainstorms were reduced with D + M, and the root morphology showed a significant correlation with DOC concentration. Compared to the D, SOC in layers 40–60 cm of the M and the D + M increased by 68.36% and 64.24%, respectively. TP and POC of the D + M increased with soil depth. Relationships between cropping pattern and rainfall intensity for particulate organic carbon (POC) and mineral-associated organic carbon (MOC) were observed. Heavy rainstorms reduced MOC, including the decomposition of substances related to the MOC, such as ROC and DOC, then POC in layers 40–60 cm increased; compared with 0–20 cm of D and M, the content of readily oxidizable carbon (ROC) in layers 40–60 cm reduced by 56.90~77.64%, and the POC increased by 38.38~87.00% in the D + M. Therefore, it was suggested that the decomposition of deeper MOC due to heavy rainstorms is the main source of soil POC and leaching DOC. This will provide a reference basis for research on assessing soil carbon-leaching fluxes and carbon stocks under extreme rainfall events. Full article

The aim of the conducted research was to assess the impact of gypsum deposit development on changes in the radiation levels of the abiotic components of the environment. For this purpose, a study of the radioactivity of water, bottom sediment, soil, gypsum and loam samples was performed. Ground-based studies of the distribution of the values of the ambient dose equivalent rate of gamma radiation and radon flux density were also carried out. It was shown that due to the high solubility of gypsum, the degree of karstification of the territory increases under the influence of meteoric waters, and as a result of the intensification of anthropogenic impact, the degree of chemical weathering of rocks increases. This leads to a coordinated change in not only the chemical but also the radiation conditions. In particular, radioactive contamination of quarry waters and areas of increased radon flux density in soil air were established. In bottom sediments, the significant correlations of ¹³⁷Cs, ²³⁸U and ²³⁴U activity concentrations with carbonates, organic matter and soluble salts contents, as well as Fe, Zn, Cu, Cr, Pb, Ni, Mo, Cd, Co, Ti and V, indicate a significant role of the anthropogenic factor in the accumulation in bottom sediments. This factor is associated with both regional atmospheric transport (¹³⁷Cs) and the activity of the mining enterprise in the study area (²³⁸U and ²³⁴U). Full article

Global warming is driven by the increasing atmospheric emissions of greenhouse gases. Soils are highly sensitive to climate change and can shift from being carbon reservoirs to carbon sources under warmer and wetter conditions. This study is the first to simultaneously measure trace gas fluxes in Euterpe oleracea (açaí) plantations in upland areas, contrasting them with floodplain areas managed for açaí production in the eastern Amazon. Flux measurements were conducted during both the rainy and dry seasons using the closed dynamic chamber technique. In upland areas, CO₂ fluxes exhibited spatial (plateau vs. lowland) and temporal (hourly, daily, and seasonal) variations. During both the rainy and dry months, CH₄ uptake in upland soils was higher in lowland areas compared to the plateau. When comparing the two ecosystems, upland areas emitted more CO₂ during the rainy season, while floodplain areas released more CH₄ into the atmosphere. Unexpectedly, during the dry season, floodplain soils produced more CO₂ and captured more CH₄ from the atmosphere compared to upland soils. In upland areas, CO₂-equivalent production reached 59.1 Mg CO₂-eq ha⁻¹ yr⁻¹, while in floodplain areas, it reached 49.3 Mg CO₂-eq ha⁻¹ yr⁻¹. Soil organic matter plays a vital role in preserving water and microorganisms, enhancing ecosystem productivity in uniform açaí plantations and intensifying the transfer of CH₄ from the atmosphere to the soil. However, excessive soil moisture can create anoxic conditions, block gas diffusion, reduce soil respiration, and potentially turn the soil from a sink into a source of CH₄. Full article

Soil respiration (Rs) is a significant contributor to the global carbon cycle, with its two main sources—microbial (heterotrophic, Rh) and plant root (autotrophic, Ra) respiration—being sensitive to various environmental factors. This study investigates the impact of ecosystem disturbances (Ds), including fire, biogenic (insects and pathogens), and harvesting, on soil respiration in Russia’s forest ecosystems. We introduced response factors to account for the effects of these disturbances on Rh over three distinct stages of ecosystem recovery. Our analysis, based on data from case studies, remote sensing data, and the national forest inventory, revealed that Ds increase Rh by an average of 2.1 ± 3.2% during the restoration period. Biogenic disturbances showed the highest impacts, with average increases of 16.5 ± 3.2%, while the contributions of clearcuts and wildfires were, on average, less pronounced—2.0 ± 3.1% and 0.8 ± 3.3%, respectively. These disturbances modify forest soil dynamics by affecting soil temperature, moisture, and nutrient availability, influencing carbon fluxes over varying timescales. This research underscores the role of ecosystem disturbances in altering soil carbon dynamics and highlights the need for improved data and monitoring of forest disturbances to reduce uncertainty in soil carbon flux estimates. Full article

The application of digestate as a fertilizer offers a promising alternative to synthetic inputs on permanent grasslands, with benefits for productivity and environmental performance. This four-year study evaluated the impact of two digestate application methods—disc injection (I) and band spreading (S)—combined with four dose variants (0, 20, 40, and 80 m³·ha⁻¹), including split-dose strategies. Emissions of ammonia (NH₃), carbon dioxide (CO₂), and methane (CH₄) were measured using wind tunnel systems immediately after application. Vegetation status was assessed via Sentinel-2-derived Normalized Difference Vegetation Index, Normalized Difference Water Index, and Modified Soil Adjusted Vegetation Index, and agronomic performance through dry matter yield (DMY), net energy for lactation (NEL), and relative feed value (RFV). NH₃ and CO₂ emissions increased proportionally with digestate dose, while CH₄ responses suggested a threshold effect, but considering solely the disc injection, CH₄ flux did not increase markedly with higher application rates. Disc injection resulted in significantly lower emissions of the monitored fluxes than band spreading. The split-dose I_40+40 variant achieved the highest DMY (3.57 t·ha⁻¹) and improved forage quality, as indicated by higher NEL values. The control variant (C, no fertilization) had the lowest yield and NEL. These results confirm that subsurface digestate incorporation in split doses can reduce emissions while supporting yield and forage quality. Based on the findings, disc injection at 40+40 m³·ha⁻¹ is recommended as an effective option for reducing emissions and maintaining productivity in managed grasslands. Full article

The existing management strategies of macrophyte beach wrack are not always environmentally sound. In this study, we tried to assess the impact of the presence or absence of macrophyte beach wrack on the CO₂ flux and the possibility of creating an environmentally sound recycling of macrophyte beach wrack based on their removal from the beach and processing into biochar. The study was conducted on the coast of the Sea of Japan in the bay of Kievka. The Picarro G4301 portable laser gas analyzer was used to measure CO₂ fluxes in areas with and without macrophyte beach wrack. The CO₂ flux was 23 times higher at plots with macrophyte beach wrack, compared with plots without macrophyte beach wrack. In the plots after manual removal of the macrophyte beach wrack, on average, there was a 1.6-fold decrease in flow values compared to the plots with the macrophyte beach wrack. Considering the frequency of emissions in the study area, which is associated with frequent cyclones and storms, it is possible to organize the systematic cleaning of macrophyte beach wrack for the production of biochar. Creating projects based on the conversion of macrophyte beach wrack into biochar can have both environmental and economic benefits. The environmental benefits include the reduction of CO₂ flux at plots after manual removal of macrophyte beach wrack; the long-term storage of carbon from macrophyte beach wrack biomass in the form of biochar; and the reduction of CO₂ flux from soils (carbon sequestration) with the correct technology of introducing biochar into the soil. However, for a more accurate assessment, monitoring seasonal measurements and economic calculations of the entire technological chain of production, risks, and footprint are necessary. Full article

Applying organic amendments enhances agroecosystem multifunctionality (EMF), yet its mechanisms via soil food-web energetics remain unclear. A field experiment was conducted on China’s Loess Plateau in a winter wheat system, comparing mineral fertilizer with straw, biochar, and liquid organic fertilizer to assess their impacts on nematode communities and EMF (plant performance and carbon, nitrogen, phosphorus cycling). Using high-throughput sequencing and energy flux modeling, we found that straw and biochar enhanced nematode diversity and co-occurrence network complexity, while liquid organic fertilizer reduced network complexity. Straw balanced fungal- and bacterial-driven energy pathways, enhancing energy flow uniformity (1.05) and EMF. However, its high C:N ratio requires mineral fertilizers to alleviate nitrogen limitations, ensuring stable bacterial energy fluxes and preventing functional trade-offs. Biochar elevated total energy flux but prioritized bacterial- and herbivore-driven pathways, reducing energy flow uniformity (0.76) and functional balance. Liquid organic fertilizer favored omnivores-predators, destabilizing lower trophic functions with minimal functional gains. Amendment properties (C:N ratio, pH) shaped nematode-mediated energy distribution, linking biodiversity to multifunctionality. Overall, straw is optimal for supporting EMF when combined with mineral fertilizers, while biochar and liquid fertilizer require tailored management to mitigate functional trade-offs. These findings advance sustainable strategies for dryland agroecosystems in the Loess Plateau region and similar environments. Full article

Soil viruses, ubiquitous and abundant biological entities that are integral to microbial communities, exert pivotal impacts on ecosystem functionality, particularly within carbon (C) and nitrogen (N) cycles, through intricate interactions with bacteria, archaea, fungi, and other microbial taxa. While their contributions to soil ecosystem dynamics are increasingly elucidated, the specific roles of soil viruses in karst forest soil remain largely underexplored. Karst ecosystems (covering 15% of the global terrestrial surface) are characterized by unique geological formations, thin and patchy soil layers, high pH and Ca²⁺, and rapid hydrological dynamics, collectively fostering unique environmental conditions that may shape viral ecology and modulate C and N cycling. This perspective synthesizes existing knowledge of soil viral functions with the distinctive characteristics of karst forest soil, proposing potential mechanisms by which soil viruses could influence C and N cycling in such fragile ecosystems. Soil viruses regulate C and N cycles both directly and indirectly via their interactions with microbial hosts, mainly including shaping the microbial community structure, mediating horizontal gene transfer and microbial metabolism, increasing C and N availability and alleviating nutrient limitations, promoting C and N sequestration, and mitigating climate change. This work aims to bridge soil viral ecology and karst biogeochemical cycles, providing insights into sustainable forest stewardship and climate resilience. We delineate critical knowledge gaps and propose future perspectives, advocating for targeted metagenomic and long-term experimental studies into viral diversity, virus–host-environment interactions, and temporal dynamics. Specifically, we advocate the following research priorities to advance our understanding of soil viruses in karst forest ecosystems in future studies: (I) soil viral diversity, abundance, and activity: characterizing the diversity, abundance, and activity of soil viruses in karst forests using metagenomics and complementary molecular approaches; (II) virus–host interactions: investigating the dynamics between the viruses and key microbial taxa involved in C and N cycling; (III) biogeochemical impacts: quantifying the contributions of viral lysis and horizontal gene transfer to C and N fluxes within karst forest soil; and (IV) modeling the viral impacts on C and N cycles: developing integrative models that incorporate soil virus-mediated processes into existing karst forest soil biogeochemical frameworks at different temporal and spatial scales. Such efforts are essential to validate the hypothesized viral roles and underlying mechanisms, offering a foundation for nature-based solutions to facilitate C and N cycling and support ecological restoration in vulnerable karst regions amid global climate change. Full article

The soil microbial community plays a crucial role in the elemental cycling and energy flow within wetland ecosystems. The temporal dynamics and spatial distribution of soil microbial communities are central topics in ecology. While numerous studies have focused on wetland microbial community structures at low altitudes, microbial diversity across seasons and depths and their environmental determinants remain poorly understudied. To test the seasonal variation in microbial communities with contrasting seasonal fluxes of greenhouse gases, a total of 36 soil samples were collected from different depths in the Namco wetland on the Tibetan Plateau across four seasons. We found significant seasonal variation in bacterial community composition, most pronounced in the Winter, but not in archaea. In particular, Proteobacteria decreased by 11.5% in Winter compared with other seasons (p < 0.05). The bacterial alpha diversity showed hump-shaped seasonal patterns with lower diversity in Winter, whereas archaea showed no significant patterns across depths. A PERMANOVA further revealed significant differences in the bacterial community structure between Winter and the other three seasons (p < 0.05). In addition, bacterial and archaeal community structures differed between surface (0–5 cm) and deeper (5–30 cm) soils (p < 0.01). Redundancy analysis showed that soil total nitrogen, soil total phosphorus, and total soil organic carbon significantly influenced bacteria and archaea (p < 0.05). Furthermore, soil moisture content and temperature strongly affected the bacterial community structure (p < 0.001). Our findings highlighted the seasonal variation in the microbial community and the profound influence of soil moisture and temperature on microbial structure in alpine wetlands on the Tibetan Plateau. Full article