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Abstract This article introduces a Wasserstein distance‐based distributionally robust optimization model to address the transmission expansion planning considering renewable‐based microgrids (MGs) under the impact of uncertainties. The primary objective of the presented methodology is to devise a robust expansion strategy that accounts for both long‐term uncertainty and short‐term variability over the planning horizon from the perspective of a central planner. In this framework, the central planner fosters the construction of appropriate transmission lines and the deployment of optimal MG‐based generating units among profit‐driven private investors. The Wasserstein distance uncertainty set is used to characterize the long‐term uncertainty associated with future load demand. Short‐term uncertainties, stemming from variations in load demands and production levels of stochastic units, are modeled through operating conditions. To ensure the tractability of the proposed planning model, the authors introduce a decomposition framework embedded with a modified application of Bender's method. To validate the efficiency and highlight the potential benefits of the proposed expansion planning methodology, two case studies based on simplified IEEE 6‐bus and IEEE 118‐bus systems are included. These case studies assess the effectiveness of the presented approach, its ability to navigate uncertainties, and its capacity to effectively optimize expansion decisions.

Societal Impact Statement As cities grow, it is essential to understand how landscape management decisions in urban spaces alter ecosystem function. This study demonstrates that the ubiquitous practice of long‐term leaf litter removal in suburbs, even in relatively small patches of a yard, reduces the soil's ability to cycle nutrients in plant litter and results in lower amounts of carbon stored in the soil. Even two years of retaining leaves where they previously were removed is insufficient to restore decomposition rates or carbon pools. This research is an important step in creating best practices for litter management to maintain essential ecosystem functions, like carbon sequestration, water holding capacity, and soil fertility. Summary Seasonal senesced leaf litter removal eliminates considerable organic material from suburban soils annually. We test if this disturbance alters decomposition and carbon cycles and depletes soils of organic matter over time, creating persistent legacy effects. We used a factorial experimental design to implement 1–2 years of current leaf litter manipulations (remove or retain fallen leaves) within historically raked and unraked areas in suburban Maryland yards. We then compared total organic soil carbon and decomposition using a standardized substrate decomposition methodology (Tea Bag Index) across treatment plots. Long‐term litter removal in suburban yards reduced decomposition rates by 17% and total soil organic carbon concentration by up to 24% compared to areas where leaf litter was retained in situ. In contrast, short‐term management changes (1–2 years) did not significantly impact decomposition rates or total organic soil carbon concentrations. Our findings suggest that long‐term suburban litter raking creates legacy effects that alter decomposition and carbon storage process trajectories that are not easily reversed. This is important in understanding urban ecosystem function and sustainable management.

Abstract The carbon capture‐transportation‐utilization (C‐CTU) chain strengthens the coupling between terminal energy consumption and renewable energy resources (RES), achieving carbon emission reduction in power generation sectors. However, the dynamic operation of the C‐CTU chain and the uncertainties induced by RES output pose new challenges for the low‐carbon operation. To address above challenges, the nonlinear dynamic operation model of C‐CTU chain is first proposed in this study. It is further incorporated into the day‐ahead operation scheme of the electricity‐carbon integrated system considering the stochastic nature of wind power. This scheme is treated as a two‐stage stochastic integer programming (TS‐SIP) problem with a mixed‐integer nonlinear recourse. By means of the polyhedral envelope‐based linearization method, this recourse is reformulated into its linear counterpart. To further improve the computational performance of classical decomposition algorithms, a novel Benders decomposition framework with hybrid cutting plane strategies is proposed to obtain better feasible solutions within a limited time. Simulations are conducted on two power system test cases with the C‐CTU chain. Numerical results indicate that the engagement of C‐CTU chain promotes the low‐carbon economic operation of the power system. Also, the proposed decomposition algorithm shows a superior solution capability to handle large‐scale TS‐SIP than state‐of‐the‐art commercial solvers.

Abstract Globally, coal is a critical energy source, and the profits of related enterprises are highly related to changes in the coal price. A robust coal purchasing cost forecasting method may enhance the coal purchasing strategies of coal‐consuming enterprises and obtain key information for reducing global carbon emissions. However, forecasting the price of coal is a challenging task due to the noise and high random fluctuation of coal price data. To overcome these obstacles, this research proposes a novel forecasting method combining data decomposition, semisupervised feature engineering, and ensemble learning to forecast coal prices. Initially, the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) method is employed to decompose the coal price series to reduce the complexity. Second, considering the fluctuation of coal price is influenced by various factors (such as transportation cost and coal mine production), the proposed system incorporates an adaptive data fusion module to fuse data from multiple sources. Finally, a stacking‐based ensemble learning model is adopted in the method to increase the forecasting accuracy by combining the forecasting results of multiple models. The Bohai‐Rim Steam‐Coal Price Index was used to validate the proposed method, and the result of the case study shows that the proposed method provides superior performance than the other nine baseline models in all measured indices. The outcomes of ablation tests indicate the precision of each algorithm is improved by combining CEEMDAN, which proves that the decomposition algorithm is necessary.

Abstract Due to the nonlinear nature of continuous phase modulation (CPM), most existing unambiguous acquisition algorithms are ineffective in eliminating the ambiguity threat faced by semi‐integer CPM signals. To address this issue, this letter proposes an unambiguous acquisition algorithm based on sub‐correlation functions combination (SCFC). The main idea of this algorithm is to decompose the first pulse amplitude modulation waveform derived from the Laurent decomposition into sub‐signal waveforms that are appropriate for CPM signals. The final unambiguous function is obtained by combining the autocorrelation function of the received CPM signal with the sub‐correlation functions derived from the sub‐signal waveforms and the received CPM signal. Simulation results demonstrate that the SCFC algorithm can eliminate the ambiguity threat of semi‐integer CPM signals with relatively minor detection loss. Moreover, the proposed algorithm successfully retains a narrow main peak and exhibits superior multipath resistance.

Abstract Pesticides can have unintentional effects on non‐target organisms and change biotic communities. Such changes might be particularly important in soil microbial communities, which drive many ecosystem functions and may affect crop quality. Here, we investigated, in a three‐year study, how vegetation control (by herbicide application) and soil copper content (from long‐term copper‐based fungicide application) affect biodiversity and the community structure of soil bacteria, fungi and protists, and associated soil functions (respiration, decomposition) in Swiss vineyards. Furthermore, we determined the effects of these two management practices on grape quality as the most direct ecosystem service to farmers. Across all study years, the community composition of microorganisms was affected by herbicide application, however, a significant loss of operational taxonomic units (OTUs) was only observed in fungi and protists. Soil copper content reduced OTU richness of bacteria and protists in some years but had no significant effect on fungal richness. Copper changed the community composition in all three groups of soil microorganisms. While we found no effect of copper on soil functions, herbicide application reduced microbial respiration and biomass by about 39% and 45%, respectively. However, decomposition rates remained virtually unchanged by any pesticide. Yeast assimilable nitrogen (YAN) levels in grape were below the critical threshold of 140 mg/L in 40% of the vineyards without herbicide application and the variety Chasselas, whereas in vineyards with herbicide application, it was only 20%. Application of pesticides led to changes in richness and composition of soil microbial communities and directly reduced some soil functions (microbial biomass and respiration) but not all (decomposition). Some grape quality parameters can be indirectly enhanced by pesticide application, highlighting the trade‐off between the interests of nature conservation and the interests of the farmer. Balancing these two diverging interests requires the establishment of alternative vineyard management allowing reduced pesticide application.

Abstract Targets with rotating components generate micro‐motion (MM) modulation effect in addition to the main body. Extracting MM parameters is challenging due to interference from the target's main body, necessitating the separation of modulation signals. This letter proposes a robust complex local mean decomposition (RCLMD) method with self‐adaptive sifting stopping, aiming at the problem of component redundancy due to multiple iterations during break and the loss of modulation components during the separation process. The proposed method sets the objective function and self‐adaptive stopping criterion, combined with the modulation signal characteristics, enhancing the accuracy and efficiency of MM component extraction. Simulation experiments show that compared with the complex local mean decomposition method, the complex empirical mode decomposition method, and its improved method, the RCLMD method can achieve the highest decomposition effect of 96.57%, and the separation time consumed has a significant advantage over the above methods, performance is less fluctuating by the change of signal‐to‐noise ratio with good robustness. The measured data in real scenarios also verify the effectiveness of the proposed method.

Abstract Habitat degradation and associated reductions in ecosystem functions can be reversed by reintroducing or ‘rewilding’ keystone species. Rewilding projects have historically targeted restoration of processes such as grazing regimes or top‐down predation effects. Few projects focus on restoring decomposition efficiency, despite the pivotal role decomposition plays in global carbon sequestration and nutrient cycling. Here, we tested whether rewilding entire communities of detritivorous invertebrates and fungi can improve litter decomposition efficiency and restore detritivore communities during ecological restoration. Rewilding was conducted by transplanting leaf litter and soil, including associated invertebrate and fungal communities from species‐rich remnant sites into species‐poor, and geographically isolated, revegetated farmland sites in a temperate woodland region of southeastern Australia. We compared communities in sites under the following treatments: remnant (conservation area and source of litter transplant), rewilded revegetation (revegetated farmland site with litter transplant) and control revegetation (revegetated site, no transplant). In one ‘before’ and three ‘after’ sampling periods, we measured litter decomposition and the abundance and diversity of detritivorous invertebrates and fungi. We quantified the effect of detritivores on the rate of litter decomposition using piecewise Structural Equation Modelling. Decomposition was significantly faster in rewilding sites than in both control and remnant areas and was largely driven by a greater abundance of invertebrate detritivores. Similarly, the abundance of invertebrate detritivores in rewilding revegetation sites exceeded the level of remnant communities, whereas there was little difference between control and remnant sites. In contrast, rewilding did not increase saprotrophic fungi relative abundance/diversity and there was no strong relationship between decomposition and fungal diversity. Our findings suggest the relatively simple act of transplanting leaf litter and soil can increase functional efficiency during restoration and alter community composition. Our methods may prove important across a range of contexts where other restoration methods have failed to restore ecosystem processes to pre‐degradation levels.

Abstract Mycorrhizal associations of trees play a key role in ecosystem biogeochemistry, yet we know relatively little about the nutrient acquisition strategies of ericoid mycorrhizal (ErM) shrubs, despite their prevalence in forest understories. ErM shrubs tend to produce litter with high concentrations of polyphenols, which form decay‐resistant complexes with organic nitrogen (N). Some ErM fungi appear capable of producing a diverse suite of extracellular enzymes, but it is unclear whether this enables ErM shrubs to acquire the N from their own litter, and whether this ability is greater than that of ectomycorrhizal (EcM) trees, with which they commonly co‐occur. Here, we conducted two growth chamber experiments with 15N‐enriched root and leaf litters to determine whether EcM pine and ErM vaccinium differ in litter N acquisition from these sources. Grown individually, pine and vaccinium plants acquired 1 mg or 4% of the litter N after one year. Differences between pine and vaccinium in litter N acquisition were correlated with litter chemistry, where vaccinium acquired more N from litter with a high concentration of tannins and a high C:N, while pine acquired more N from litter with a high acid‐insoluble fraction. When plants were grown in pairs, the presence of a vaccinium neighbor reduced the biomass of both species by an average of 24%, but it only reduced litter N acquisition by pine (55%), demonstrating vaccinium's ability to compete with pine for litter N. Regardless of the competitive context, vaccinium allocated a greater percentage (76%) of its acquired litter N to aboveground biomass compared with pine (47%), suggesting vaccinium is more efficient at allocating this N to photosynthesis and growth. Our finding that EcM pine and ErM vaccinium have varying abilities to acquire N from these common litters suggests a degree of niche complementarity, which may facilitate the coexistence of these plants in forest ecosystems. However, our results also suggest that, at high densities, ErM vaccinium has the potential to suppress the growth and N acquisition of EcM pine. Distinct strategies of EcM trees and ErM shrubs for acquiring and using N have the potential to shape biogeochemical cycles of many forested ecosystems.

Abstract Predicting how increasing temperatures interact with other global change drivers to influence the structure and dynamics of Earth's ecosystems is a primary challenge in ecology. Our study made use of multiple simultaneous “natural experiments” to examine how rapid warming, declining nutrients, invasive consumers, and riparian invasive species management interact to influence leaf decomposition in a large and regulated river. Specifically, we compared the breakdown of cottonwood (Populus fremontii), willow (Salix exigua), and saltcedar (Tamarix sp.) leaf litter in 2022 to a previous experiment from 1998 that occurred under much cooler water temperatures, and had higher water phosphorus concentrations, low numbers of invasive New Zealand mudsnails (Potamopyrgus antipodarum), and unaltered litter chemistry from the herbivory of saltcedar leaf beetles (Diorhabda carinulata). We found that the effects of up to 10°C warmer temperatures on leaf decomposition were mediated by the establishment and management of invasive species and declining water nutrient concentrations arising from upstream reservoir lowering. Such interactions led to accelerated breakdown of saltcedar, but relatively minor effects of warming on the rate of cottonwood and willow decomposition. Additionally, our results demonstrate the potential for favorable invasive species management outcomes in the terrestrial environment to produce unintended responses in adjacent freshwater ecosystems. As temperatures continue to rise, it is critical that future studies consider how warming interacts with multiple stressors and environmental factors to influence processes such as decomposition in freshwater ecosystems.

Abstract It has long been recognized that diversity has many measurable aspects, such as richness, evenness, and similarity among species. However, given a diversity index, it is unclear whether it necessarily can be decomposed into components that reflect these different aspects. Here, we present a scheme to decompose the Leinster and Cobbold diversity index, which subsumes and generalizes many other indices, into the components of richness, evenness and taxonomic similarity. Our approach addresses the problem that in general a vector of equal relative abundances does not maximize diversity. Furthermore, our approach uses all available information to give unbiased estimates of both evenness and similarity.

Abstract We explored the first evidence of a single‐session neuromuscular biofeedback effect on motor unit properties, neuromuscular activation, and the Achilles tendon (AT) length 12 days after undergoing AT surgical repair. We hypothesized that immediate neuromuscular biofeedback enhances motor unit properties and activation without causing AT lengthening. After 12 days AT surgical repair, Medial Gastrocnemius (MG) motor unit decomposition was performed on a 58‐year‐old male before and after a neuromuscular biofeedback intervention (surface electromyography (sEMG) and ultrasonography), involving unressited plantar flexion. The analysis included motor unit population properties, sEMG amplitude, force paradigm, and AT length. There were increased MG motor unit recruitment, peak and average firing rate, coefficient of variation, and sEMG amplitude, and decreased recruitment and derecruitment threshold in the repaired AT limb. The non‐injured limb increased the motor unit recruitment, and decreased the coefficient of variation, peak and average firing rate, inter‐pulse interval, derecruitment threshold and sEMG amplitude. The AT length experienced −0.4 and 0.3 cm changes in the repaired AT and non‐injured limb, respectively. This single‐session neuromuscular biofeedback 12 days after AT surgery shows evidence of enhanced motor unit properties and activation without signs of AT lengthening when unresisted plantar flexion is performed in the repaired AT limb.

Protists show diverse lifestyles and fulfill important ecological roles as primary producers, predators, symbionts, and parasites. The degradation of dead microbial biomass, instead, is mainly attributed to bacteria and fungi, while necrophagy by protists remains poorly recognized. Here, we assessed the food range specificity and feeding behavior of the algivorous flagellate Orciraptor agilis (Viridiraptoridae, Cercozoa) with a large-scale feeding experiment. We demonstrate that this species is a broad-range necrophage, which feeds on a variety of eukaryotic and prokaryotic algae, but fails to grow on the tested fungi. Furthermore, our microscopic observations reveal an unexpected flexibility of O. agilis in handling food items of different structures and biochemistry, demonstrating that sophisticated feeding strategies in protists do not necessarily indicate narrow food ranges., (© 2024 The Author(s). Journal of Eukaryotic Microbiology published by Wiley Periodicals LLC on behalf of International Society of Protistologists.)

Abstract Dung beetles are important actors in the self‐regulation of ecosystems by driving nutrient cycling, bioturbation, and pest suppression. Urbanization and the sprawl of agricultural areas, however, destroy natural habitats and may threaten dung beetle diversity. In addition, climate change may cause shifts in geographical distribution and community composition. We used a space‐for‐time approach to test the effects of land use and climate on α‐diversity, local community specialization (H2′) on dung resources, and γ‐diversity of dung‐visiting beetles. For this, we used pitfall traps baited with four different dung types at 115 study sites, distributed over a spatial extent of 300 km × 300 km and 1000 m in elevation. Study sites were established in four local land‐use types: forests, grasslands, arable sites, and settlements, embedded in near‐natural, agricultural, or urban landscapes. Our results show that abundance and species density of dung‐visiting beetles were negatively affected by agricultural land use at both spatial scales, whereas γ‐diversity at the local scale was negatively affected by settlements and on a landscape scale equally by agricultural and urban land use. Increasing precipitation diminished dung‐visiting beetle abundance, and higher temperatures reduced community specialization on dung types and γ‐diversity. These results indicate that intensive land use and high temperatures may cause a loss in dung‐visiting beetle diversity and alter community networks. A decrease in dung‐visiting beetle diversity may disturb decomposition processes at both local and landscape scales and alter ecosystem functioning, which may lead to drastic ecological and economic damage.

Abstract Ecosystems have been shaped by fire for millions of years. Many oligotrophic ecosystems rely on fire for biogeochemical cycling and maintenance of key processes. However, it is uncertain how fire intensity interacts with nutrient limitation to drive differential responses in postfire biogeochemical cycling and ecosystem recovery. In this study, we compare pre‐ and postfire carbon and nutrient pools in two adjacent wetlands characterized by either lower or higher phosphorus (P) inputs and thus different levels of P limitation. Carbon (C), nitrogen (N), and P pools and litter and root decomposition rates were measured starting 1 year prefire until 1 year postfire in lower‐P (LP) and higher‐P (HP) freshwater marshes of the Florida Everglades. Dominant vegetation biomass and vegetation composition were monitored as well. Fire energy release was measured to link the causal mechanism, heat transfer, to nutrient fluxes. We observed temporary increases in surface water, periphyton, and leaf tissue P concentrations in both wetland types following fire. Soil P increased and soil C:P and N:P ratios decreased postfire in the LP wetland but did not change in the HP wetland. Prefire soil P was greater in the HP than the LP wetland, but did not differ 1 month or 1 year postfire. Vegetation structure and composition were marginally affected by fire. Fire intensity was highly variable within both wetlands. Increasing fire intensity correlated with increasing accumulation of soil organic matter in the LP wetland, and with increases in decomposition rates in both wetland types, between pre‐ and postfire. Litter and root decomposition rapidly increased with increasing fire intensity, but seemed to stabilize after a certain fire intensity threshold was reached. Our results indicate that fire can temporarily ease P limitation in oligotrophic wetlands, by affecting soil nutrient stoichiometry and organic matter processing, while maintaining vegetation community composition. Further, we identified fire dosing, expressed as the fire radiative energy release, to be an effective control of postfire biogeochemical cycling. Hence, nutrient management should be incorporated into burn prioritization tools and, when applying prescribed fires, natural resource managers should also consider how fire attributes, such as fire intensity, impact nutrient cycling and other soil processes.

Abstract The decomposition of organic matter is a fundamental ecosystem‐level process that governs nutrient cycling, fuels ecosystems, and impacts our global climate. Despite the central importance of this process for ecosystems across the planet, little is known about how the capacity of ecosystems to decompose organic matter—that is, their decomposition potential—varies across time and space. Closing this gap is needed to provide baseline information on the dynamics of ecosystems, for tracking anthropogenic impacts, and for development of practical and efficient sampling procedures. For nine consecutive years during the months of July–August, we deployed an identical organic‐matter decomposition assay in the same 26 temperate deciduous‐forest streams (234 stream‐years total) to evaluate the interannual and among‐stream variation in the decomposition of organic matter. Decomposition rates (as k values) ranged widely across all stream‐years (mean = 0.026, SD = 0.018, range = 0.0020–0.094). Interestingly, among‐stream variation, expressed on a per‐stream basis, was more than three times greater than interannual variation (expressed on a per year basis), explaining 75% and 22% of the overall variation in our dataset, respectively. Removing the effects of temperature by adjusting decomposition rates for degree days did not substantially impact this pattern (stream: 80% of variation, year: 17% of variation). Surprisingly, despite large differences in temperature among streams, temperature explained little variation in decomposition rates, pointing to the importance of other factors. When compared to the decomposition rates from stream sites across the planet, the rates presented here spanned 27.3% of this range, highlighting the diversity of decomposition rates that can be found in a relatively compact geographic area. From the perspective of using organic‐matter decomposition as a bioassessment tool, this variation could limit the sensitivity of decomposition‐based assays to human impacts, although study designs could be utilized to ameliorate this problem (e.g., those that stratify by geology). The results and dataset presented here are a needed step toward a more complete understanding of how ecosystem processes vary across time and space.

Abstract Decomposition is essential to carbon, nutrient, and energy cycling among and within ecosystems. Several methods have been proposed for studying litter decomposition by using a standardized and commercially available substrate. One of these methods is the Tea Bag Index (TBI) which uses tea bags (green and rooibos tea) incubated for ~90 days. The TBI is now applied all over the globe, but despite its usefulness and wide application, the TBI (as well as other methods) does not explicitly account for the differences in potential loss of litter mass due to initial leaching in habitats with large differences in moisture. We, therefore, studied the short‐term mass losses (3–4 h) due to initial leaching under field and laboratory conditions for green and rooibos tea using the TBI and contextualized our findings using existing long‐term mass loss (90 days) in the field for both aquatic and terrestrial environments. For both tea litter types, we found a fast initial leaching rate, which could be mistaken for decomposition through microbial activity. This initial leaching was higher than the hydrolyzable fraction given in the description of the TBI. We also found that leaching increased with increasing temperature and that leaching in terrestrial environments with high soil moisture (>90%) is almost as large as in aquatic environments. When comparing our findings to long‐term studies, we found that up to 30–50% of the mass loss of green tea reported as decomposition could be lost through leaching alone in high moisture environments (>90% soil moisture and submerged). Not accounting for such differences in initial leaching across habitats may lead to a systematic overestimation of the microbial decomposition in wet habitats. Future studies of microbial decomposition should adjust their methods depending on the habitat, and clearly specify the type of decomposition that the study focuses on.

Abstract Decomposition of vegetal detritus is one of the most fundamental ecosystem processes. In complex landscapes, the fate of litter of terrestrial plants may depend on whether it ends up decomposing in terrestrial or aquatic conditions. However, (1) to what extent decomposition rates are controlled by environmental conditions or by detritus type, and (2) how important the composition of the detritivorous fauna is in mediating decomposition in different habitats, remain as unanswered questions. We incubated two contrasting detritus types in three distinct habitat types in Coastal Georgia, USA, to test the hypotheses that (1) the litter fauna composition depends on the habitat and the litter type available, and (2) litter mass loss (as a proxy for decomposition) depends on environmental conditions (habitat) and the litter type. We found that the abundance of most taxa of the litter fauna depends primarily on habitat. Litter type became a stronger driver for some taxa over time, but the overall faunal composition was only weakly affected by litter type. Decomposition also depends strongly on habitat, with up to ca. 80% of the initial detrital mass lost over 25 months in the marsh and forest habitats, but less than 50% lost in the creek bank habitat. Mass loss rates of oak versus pine litter differed initially but converged within habitat types within 12 months. We conclude that, although the habitat type is the principle driver of the community composition of the litter fauna, litter type is a significant driver of litter mass loss in the early stages of the decomposition process. With time, however, litter types become more and more similar, and habitat becomes the dominating factor in determining decomposition of older litter. Thus, the major driver of litter mass loss changes over time from being the litter type in the early stages to the habitat (environmental conditions) in later stages.

Abstract Dead animal biomass (carrion) is present in all terrestrial ecosystems, and its consumption, decomposition, and dispersal can have measurable effects on vertebrates, invertebrates, microbes, parasites, plants, and soil. But despite the number of studies examining the influence of carrion on food webs, there has been no attempt to identify how general ecological processes around carrion might be used as an ecosystem indicator. We suggest that knowledge of scavenging and decomposition rates, scavenger diversity, abundance, and behavior around carrion, along with assessments of vegetation, soil, microbe, and parasite presence, can be used individually or in combination to understand food web dynamics. Monitoring carrion could also assist comparisons of ecosystem processes among terrestrial landscapes and biomes. Although there is outstanding research needed to fully integrate carrion ecology and monitoring into ecosystem management, we see great potential in using carrion as an ecosystem indicator of an intact and functional food web.

Abstract The application of biochar to land has been promoted as a strategy for sequestering carbon in soils, for improving soil fertility and remediating soil pollution. However, the implications of biochar amendments on mycorrhizal associations and pesticide decomposition in agricultural soils are poorly understood. In this study, we compared the effects of four treatments; control (no biochar and no arbuscular mycorrhizal fungi (AMF), biochar (biochar without AMF), AMF (AMF without biochar) and biochar + AMF (AMF and biochar) on the fate of simazine. We specifically focused on the sorption, leaching and biodegradation behaviour of simazine. Our results showed that when symbiosis existed between plants and AMF, biochar inhibited simazine decomposition and AMF inoculation alleviated this inhibition. In contrast, this alleviation was not observed when the plant was removed. In addition, AMF inoculated into the biochar amended soil significantly decreased simazine concentration in the leachate; however, in the AMF‐only treatment, no effect on simazine leaching was observed. These phenomena were attributed to variation in the soil's sorption capacity due to biochar application or AMF inoculation. Overall, biochar application combined with AMF inoculation has the potential to mitigate simazine accumulation in the topsoil and reduce its availability.

Abstract Desertification land in Gonghe Basin of Tibetan Plateau, China accounts for 91.9% of the total land area. Vegetation restoration and reconstruction with desert shrubs in degraded ecosystem are effective ways to prevent and control desertification. However, the evaluation studies of fine root dynamic characteristics of desert shrubs and their contribution to carbon sequestration of plantation are limited. To gain a better understanding of vegetation restoration, the vertical distribution of fine root biomass, fine root decomposition, fine root turnover was investigated, as well as their coupling effect on carbon sequestration of plantation in three desert vegetation. The results estimated that the total decomposition time of fine roots of Salix cheilophila (S. cheilophila), Salix psammophila (S. psammophila), and Salix microstachya (S. microstachya) are 39.00, 27.99 and 35.95 years. Biomass carbon density for three Salix plantations ranged from 1.42 to 2.39 t/hm2, which showed that three Salix plantations in alpine sandy land are an important carbon pool. In addition, fine root biomass carbon density for the three shrub plantations varied significantly. Fine root biomass carbon density for S. psammophila reached the largest among the three plantations, which was 1.48 t/hm2, accounting for the ratio of 62% of the plantation total biomass carbon density. The results indicated that the root system of S. psammophila, especially the fine roots, was very developed, which was conducive to soil water transportation and carbon sequestration. Therefore, S. psammophila might be a better species for carbon sequestration of plantation in alpine sandy areas. The carbon input from the fine roots of the three shrub plantations through decomposition and turnover into the plantations accounts for 11.5% to 15.5% of total carbon sequestration of plantations. Therefore, the fine roots dynamics must be considered for long‐term carbon pool estimations in three Salix plantations, otherwise the total carbon sequestration of plantations would be underestimated.

Abstract In tropical forest ecosystems leaf litter from a large variety of species enters the decomposer system, however, the impact of leaf litter diversity on the abundance and activity of soil organisms during decomposition is little known. We investigated the effect of leaf litter diversity and identity on microbial functions and the abundance of microarthropods in Ecuadorian tropical montane rainforests. We used litterbags filled with leaves of six native tree species (Cecropia andina, Dictyocaryum lamarckianum, Myrcia pubescens, Cavendishia zamorensis, Graffenrieda emarginata, and Clusia spp.) and incubated monocultures and all possible two‐ and four‐species combinations in the field for 6 and 12 months. Mass loss, microbial biomass, basal respiration, metabolic quotient, and the slope of microbial growth after glucose addition, as well as the abundance of microarthropods (Acari and Collembola), were measured at both sampling dates. Leaf litter diversity significantly increased mass loss after 6 months of exposure, but reduced microbial biomass after 12 months of exposure. Leaf litter species identity significantly changed both microbial activity and microarthropod abundance with species of high quality (low C‐to‐N ratio), such as C. andina, improving resource quality as indicated by lower metabolic quotient and higher abundance of microarthropods. Nonetheless, species of low quality, such as Clusia spp., also increased the abundance of Oribatida suggesting that leaf litter chemical composition alone is insufficient to explain variation in the abundances of soil microarthropods. Overall, the results provide evidence that decomposition and microbial biomass in litter respond to leaf litter diversity as well as litter identity (chemical and physical characteristics), while microarthropods respond only to litter identity but not litter diversity.

Objective: This study aims to determine the indicators of tobacco use in Türkiye within a multidimensional context as socio-demographic, physical, behavioural, and psychological as a response to the tobacco control policies., Methods: The Turkish Health Survey data in 2014 and 2019 are employed within a probit model approach and the differences in tobacco are decomposed use by gender in order to reveal the gender differences. The samples in 2014 (total n = 19,129; males = 8 721, females = 10,408) and 2019 (total n = 17,084; males = 7 784, females = 9300) were restricted to 15-year-old and above., Results: The findings indicate that being in the 30-49 age cohort, having lower education, and being married increase the likelihood of tobacco use. Future policies and campaigns should specifically target the single, pre-obese, employed males who consume alcohol. For females, the gender-specific policies should aim to reduce the prevalence of smoking, especially among separated or widows, obese, and out of the labour force. The contribution of mental health indicators on tobacco use has declined over the 5 years, which could be a result of the supportive free health services in Türkiye. The findings provide evidence for a significant and increasing gender difference in tobacco use in Türkiye along with reporting that the most significant contributors to gender differences in tobacco use are alcohol consumption and education level., Conclusion: Even though the Ministry of Health and the government have been implementing anti-tobacco policies, legislations, and campaigns for years, the tobacco use prevalence has remained high and even increased in Türkiye., (© 2024 John Wiley & Sons Ltd.)

Abstract As tall shrubs increase in extent and abundance in response to a changing climate, they have the potential to substantially alter Arctic and boreal ecosystem nutrient cycling and carbon (C) balance. Siberian alder (Alnus viridis ssp. fruticosa), a nitrogen (N) fixing shrub, is among the species responding to climate warming in both the Arctic and boreal forests. By relieving N limitation of microbial activity, alder‐fixed N has the potential to increase decomposition of labile soil C. Simultaneously, it may also decrease decomposition of recalcitrant soil C by downregulating microbial N mining. The microbial response to N additions is influenced by differences in the soil organic matter (SOM) chemistry and could ultimately determine whether alder N additions result in a net sink or source of C to the atmosphere. We measured the activities of three extracellular enzymes in bulk organic soils under and away from alder canopies in stands differing in SOM chemistry in both the arctic and boreal forest regions of Alaska, USA. In the Arctic, samples taken from under alder had higher activities of both recalcitrant and labile C‐degrading enzymes than samples taken away, regardless of SOM chemistry. In the boreal forest, enzyme activities did not differ with alder proximity nor stand SOM chemistry, possibly due to long legacies of alder N inputs in these stands. As arctic and boreal forest ecosystems experience shifts in the distribution and abundance of this N‐fixing shrub, alders' influence on soil decomposition could have significant consequences for high latitude soil C budgets.

Abstract Soil microbiomes play a key role in driving biogeochemical cycles of the Earth system. As drought frequency and intensity increase due to climate change, soil microbes and the processes they control will be impacted. Even after a drought ends, microbiomes and other systems take time to recover and may display a memory of previous climate conditions. Still, the mechanisms involved in these legacy effects remain unclear, making it difficult to predict climate and biogeochemical rates in the future. Here, we used a trait‐based microbiome model (DEMENTpy) to implement trade‐off‐mediated mechanisms that may lead to drought legacy effects on litter decomposition. Trade‐offs were assumed to follow the Y‐A‐S framework that defines three primary life‐history strategies of microorganisms: high growth Yield, resource Acquisition, and Stress tolerance. We represented cellular trade‐offs between osmolytes required for drought tolerance and investment in enzymes involved in litter decomposition. Simulations were run under varying levels of drought severity and dispersal. With high levels of dispersal, no legacy effects were predicted by DEMENTpy following drought. With limited dispersal, severe drought resulted in a persistent legacy of altered community‐level traits and reduced litter decomposition. Moderate drought resulted in a transient legacy that disappeared after two years, consistent with recent empirical observations in Southern California ecosystems. These results imply that greater movement along the trade‐off between enzyme investment and osmolyte production resulted in stronger legacy effects. More generally, factors that shift the position of a microbiome in YAS space may alter the legacy outcome following drought. Our trait‐based modeling study motivates additional empirical measurements to quantify YAS traits and trade‐offs that are needed to make accurate predictions of soil microbiome resilience and functioning. Also, our study illustrates an emerging approach for representing trait trade‐offs in microbiomes and vegetation that dictate ecosystem responses to drought and other environmental perturbations.

Abstract Human activities have led to increased deposition of nitrogen (N) and phosphorus (P) into soils. Nutrient enrichment of soils is known to increase plant biomass and rates of microbial litter decomposition. However, interacting effects of hydrologic position and associated changes to soil moisture can constrain microbial activity and lead to unexpected nutrient feedbacks on microbial community structure–function relationships. Examining feedbacks of nutrient enrichment on decomposition rates is essential for predicting microbial contributions to carbon (C) cycling as atmospheric deposition of nutrients persists. This study explored how long‐term nutrient addition and contrasting litter chemical composition influenced soil bacterial community structure and function. We hypothesized that long‐term nutrient enrichment of low fertility soils alters bacterial community structure and leads to higher rates of litter decomposition especially for low C:N litter, but low‐nutrient and dry conditions limit microbial decomposition of high C:N ratio litter. We leveraged a long‐term fertilization experiment to test how nutrient enrichment and hydrologic manipulation (due to ditches) affected decomposition and soil bacterial community structure in a nutrient‐poor coastal plain wetland. We conducted a litter bag experiment and characterized litter‐associated and bulk soil microbiomes using 16S rRNA bacterial sequencing and quantified litter mass losses and soil physicochemical properties. Results revealed that distinct bacterial communities were involved in decomposing higher C:N ratio litter more quickly in fertilized compared to unfertilized soils especially under drier soil conditions, while decomposition rates of lower C:N ratio litter were similar between fertilized and unfertilized plots. Bacterial community structure in part explained litter decomposition rates, and long‐term fertilization and drier hydrologic status affected bacterial diversity and increased decomposition rates. However, community composition associated with high C:N litter was similar in wetter plots with available nitrate detected, regardless of fertilization treatment. This study provides insight into long‐term fertilization effects on soil bacterial diversity and composition, decomposition, and the increased potential for soil C loss as nutrient enrichment and hydrology interact to affect historically low‐nutrient ecosystems.

Abstract Ecosystem responses to external inputs of nutrients and organisms are highly variable. Theory predicts that ecosystem traits will determine the responses to spatial subsidies, but evidence for how vegetation structure can modulate those effects is lacking. We investigated how vegetation structure (i.e., leaf area index [LAI] and vegetation height) influenced the ecosystem and community responses to insect spatial subsidies in a subarctic grassland. Our experiment consisted of a 2 × 2 manipulation where in one treatment we either blocked flying insects over a 2‐yr period in 1‐m2 plots near the shore of Lake Mývatn, Iceland, where deposition of aquatic adult midges (Diptera: Chironomidae) to land is high, or left control plots accessible to flying midges. In the second treatment, grassland vegetation was cut (tall vs. short) at the start of each season and then allowed to regrow. We then measured litter decomposition and arthropod composition and density within each plot (n = 6 replicates × 4 treatments). Midge‐exclusion cages reduced midge deposition by 81% relative to the open plots. Vegetation cutting initially reduced LAI and vegetation height by 3× and 1.5×, respectively, but these were not different by the end of the second‐growing season. We found that vegetation structure modulated the effects of midge subsides on litter decomposition, with taller canopies intercepting more insect subsidies than shorter ones, leading to 18% faster litter decomposition. In contrast, the short‐vegetation plots intercepted fewer subsidies and had higher temperatures and sunlight, resulting in no effects of midges on decomposition. However, by the end of the experiment when all vegetation structure characteristics had converged across all plots, we found no differences in decomposition between treatments. The effects of midge subsidies on arthropod composition depended on the vegetation structure, suggesting that arthropods might also be responding to the structural effects on spatial subsidies. Our findings indicate that vegetation structure can modify the abiotic environment and the quantity of subsidies entering a recipient ecosystem as aerial insects, resulting in ecosystem‐ and community‐level responses. Thus, changing vegetation structure via habitat disturbances will likely have important implications for ecosystem functions that rely on spatial subsidies.

Abstract Eucalyptus plantations have replaced other (agro)ecosystems over 5.6 Mha in Brazil. While these plantations rapidly accumulate carbon (C) in their biomass, the C storage in living forest biomass is transient, and thus, longer‐term sustainability relies on sustaining soil organic matter (SOM) stocks. A significant amount of harvest residues (HR) is generated every rotation and can yield SOM if retained in the field. Yet, there is little information on how managing eucalyptus HR changes SOM dynamics. We used isotopic and molecular approaches in a 3‐yr field decomposition experiment where a native grassland has been replaced by eucalyptus plantations to assess how HR management practices influence content and chemistry of two distinct SOM fractions [particulate (POM) and mineral‐associated organic matter (MAOM)] at two soil depths (0–1 and 1–5 cm). The management practices investigated were HR removal (−R), only bark removal (−B), and retention of all HR (including bark, +B), combined with two levels of nitrogen (N) fertilization [0 (−N) and 200 (+N) kg/ha]. N fertilization inhibited HR decomposition (P = 0.0409), while bark retention had little effect (P = 0.1164). Retaining HR, especially with bark, increased POM‐C and MAOM‐C content (2.1‐ and 1.2‐fold, respectively), decreased POM‐δ13C (1.2‐fold), and increased inorganic N retention (1.7‐fold) compared with plots where HR had been removed. Inorganic N applications, however, diminished the positive impacts of bark retention. Although the influence of HR management was most pronounced in POM, retaining HR reduced potential soil C mineralization by up to 20%. POM and MAOM chemistry shifted over time and revealed distinct influence of HR on the formation of these fractions. We demonstrate that HR management alters SOM dynamics and that retaining HR, particularly including bark, enhances SOM retention. With continuing conversion of native grassland ecosystems to eucalyptus, long‐term sustainability will require careful HR and fertilizer management to balance total biomass harvest with sustaining belowground SOM concentrations.

Abstract In the Intermountain West, land managers masticate pinyon pine (Pinus spp.) and juniper (Juniperus spp.) trees that have encroached sagebrush steppe communities to reduce canopy fuels, alter potential fire behavior, and promote growth of understory grasses, forbs, and shrubs. At three study sites in Utah, 45 sampling plots spanning a range of tree cover from 5% to 50% were masticated. We measured surface fuel load components three times over a 10‐yr period. We also measured tree cover, density, and height as indicators of treatment longevity. Changes in these variables were analyzed across the range of pre‐treatment tree cover using linear mixed effects modeling. We detected decreases in 1‐h down woody debris by 5–6 yr post‐treatment, and from 5–6 to 10 yr post‐treatment, but did not detect changes in 10‐h or 100 + 1000‐h down woody debris. By 10 yr post‐treatment, there was very little duff and tree litter left for all pre‐treatment tree cover values. Herbaceous fuels (all standing live and dead biomass) increased through 10 yr post‐treatment. At 10 yr post‐treatment, pinyon–juniper cover ranged 0–2.6%, and the majority of trees were

Abstract Increasing agroecosystem biodiversity with cover crops can restore many ecosystem functions that are lost with simplified crop rotations. Mixtures of species with complementary plant traits, such as legumes and grasses, may increase multiple functions at once, including soil nutrient supply and retention, which depend on microbial decomposition dynamics. Litter mixtures can stimulate decomposition compared to individual species, and decomposition also varies with soil properties. However, the interactive effect of cover crop functional type and soil fertility status on decomposition are not known. Here, we tested for mixture effects with a legume–grass litter in soils with lower and higher levels of fertility. We also identified specific soil properties that are associated with those effects. We incubated hairy vetch, cereal rye, and vetch‐rye litter treatments for 360 d in two soils from fields with contrasting management histories and fertility levels, as defined by biological indicators such as particulate organic matter (POM) pools. We measured decomposition dynamics through respired CO2, microbial biomass, microbial extracellular enzyme activity, and inorganic nitrogen (N) mineralization. With no litter addition, the soil with larger POM pools had twofold greater microbial biomass C, seven times more net N mineralization, and respired 58% more CO2. Across both soils, after 30 d microbial biomass C increased by 58–208% following litter addition, and litter addition significantly increased CO2 production compared to the no‐litter control. However, there was no difference in the magnitude of CO2 production among cover crop treatments and soils after litter addition. The lower fertility soil had a greater response to the litter C input for CO2 production and enzyme activities in soil. Furthermore, the size and N content of free and intra‐aggregate POM pools were associated with differences in the microbial response to litter addition. Our results demonstrate that cover crop litter affects microbial decomposition dynamics differently in soils with distinct soil fertility levels and suggests that new C inputs have larger effects in lower fertility soils. Understanding how soils with different fertility levels respond to diverse cover crops, including mixtures, will inform management of agroecosystems for sustainability.

Abstract Fungal mycelia can eliminate almost all cocultured cyanobacterial cells within a short time. However, molecular mechanisms of algicidal fungi are poorly understood. In this study, a time‐course transcriptomic analysis of algicidal fungus Bjerkandera adusta T1 was applied to investigate gene expression and regulation. A total of 132, 300, 422, and 823 differentially expressed genes (DEGs) were identified at 6, 12, 24, and 48 hr, respectively. Most DEGs exhibited high endopeptidase activity, cellulose catabolic process, and transmembrane transporter activity by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Many decomposition genes encoding endopeptidases were induced a little later in B. adusta T1 when compared with previously investigated algicidal fungus Trametes versicolor F21a. Besides, the accumulated expression of Polysaccharide lyases8 (PL8) gene with peptidoglycan and alginate decomposition abilities was greatly delayed in B. adusta T1 relative to T. versicolor F21a. It was implied that endopeptidases and enzymes of PL8 might be responsible for the strong algicidal ability of B. adusta T1 as well as T. versicolor F21a.

Abstract Few studies have evaluated the trophic level in tropical caves, and none related the microbial biomass dynamics in the immobilization of carbon and nitrogen. Here, four tropical caves of Terra Ronca State Park, Brazil, were studied: Angélica, São Bernardo, Terra Ronca I, and Terra Ronca II caves. Physical, chemical, and microbiological parameters (microbial biomass and respiration) were estimated in the dry and wet seasons. São Bernardo, Terra Ronca I, and Terra Ronca II caves presented higher nitrogen and microbial biomass nitrogen (MBN) values in the wet season than in the dry season. On the other hand, the Angélica cave showed larger amounts of nitrogen and lower MBN values in the dry season. These results indicate that caves can be adjusted in two ecological theories known as “stoichiometric decomposition” and “microbial nitrogen mining”—to the effects of nutrient availability on organic matter decomposition. The caves studied showed different environmental dynamics in relation to organic matter decomposition, which allows them to be considered unique and possess specific characteristics. Microbial biomass dynamics can be an important parameter to evaluate the availability of nutrients and ecological dynamics of the trophic network in subterranean environments.

Abstract The last decade has seen an extraordinary rise in the performance of perovskite solar cells (PSCs). State‐of‐the‐art devices now have efficiencies of over 25%, putting them on par with the best silicon solar cells. Yet despite their impressive performance, their longevity lags behind that of conventional silicon technology. Environmental factors like moisture, heat, and light can all adversely affect PSC performance and limit device lifetime. Systematically elucidating and eliminating PSC degradation pathways will be critical to the success of this technology. In situ techniques provide powerful tools to this end, as they allow structural, compositional, morphological, and optoelectronic changes to be tracked in real‐time. Because they follow a single film or device over the course of the degradation process, they can help eliminate the statistical variation that negatively affects many studies. Here we provide an overview of perovskite degradation processes, with an emphasis on in situ studies.

Abstract Microbially mediated decomposition of particulate organic carbon (POC) is a central component of the oceanic carbon cycle, controlling the flux of organic carbon from the surface ocean to the deep ocean. Yet, the specific microbial taxa responsible for POC decomposition and degradation in the deep ocean are still unknown. To target the active microbial lineages involved in these processes, 13C‐labeled particulate organic matter (POM) was used as a substrate to incubate particle‐attached (PAM) and free‐living microbial (FLM) assemblages from the epi‐ and bathypelagic zones of the New Britain Trench (NBT). By combining DNA stable‐isotope probing and Illumina Miseq high‐throughput sequencing of bacterial 16S rRNA gene, we identified 14 active bacterial taxonomic groups that implicated in the decomposition of 13C‐labeled POM at low and high pressures under the temperature of 15°C. Our results show that both PAM and FLM were able to decompose POC and assimilate the released DOC. However, similar bacterial taxa in both the PAM and FLM assemblages were involved in POC decomposition and DOC degradation, suggesting the decoupling between microbial lifestyles and ecological functions. Microbial decomposition of POC and degradation of DOC were accomplished primarily by particle‐attached bacteria at atmospheric pressure and by free‐living bacteria at high pressures. Overall, the POC degradation rates were higher at atmospheric pressure (0.1 MPa) than at high pressures (20 and 40 MPa) under 15°C. Our results provide direct evidence linking the specific particle‐attached and free‐living bacterial lineages to decomposition and degradation of diatomic detritus at low and high pressures and identified the potential mediators of POC fluxes in the epi‐ and bathypelagic zones.

Fluorinated nitrile (C(4)F(7)N) gas mixture has been introduced as the most promising candidate to replace sulfur hexafluoride using in gas-insulated equipment. In this study, the authors explored the influence of oxygen on the dielectric and decomposition properties of C(4)F(7)N–CO(2)–O(2) gas mixture. The authors found that the dielectric strength of the C(4)F(7)N–CO(2)–O(2) gas mixture with 2, 4, 6, 8 and 10% O(2) was increased by 4.85%, 6.49%, 7.70%, 3.21% and 2.74% compared with C(4)F(7)N–CO(2). The addition of 2–6% O(2) to the C(4)F(7)N–CO(2) gas mixture could effectively reduce the content of most of the decomposition by-products such as CF(4), CO, C(2)F(6), C(3)F(6), C(3)F(8), CF(3)CN, C(2)F(5)CN, (CN)(2). While high content of oxygen (>6%) results in higher decomposition of C(4)F(7)N, which has a negative effect on the stability of C(4)F(7)N gas mixture. Generally, it is recommended to add 2–6% O(2) in the C(4)F(7)N–CO(2) gas mixture to improve its insulation properties as well as inhibit the decomposition of C(4)F(7)N in the discharge for medium-voltage engineering application.

Dense false target jamming can affect radar detection performance severely. A method of dense false targets jamming recognition based on time-frequency atomic decomposition theory and support vector machine (SVM) is proposed to solve the difficulty of dense false targets jamming identification. According to the feature of ambiguity function of dense false targets jamming signal, a Gabor sub-dictionary which has adaptive variation with signal is designed. The signal is expanded into the corresponding Gabor time-frequency dictionary by sparse decomposition. After Gabor atomic time-frequency parameters are extracted as individual feature vectors, SVM is utilised for classification and recognition. The experimental results show that the extracted Gabor atomic time-frequency parameters can effectively represent the essential features of target and dense false targets jamming, respectively, and this method has a high recognition rate.

Abstract Warming is altering the way soils function in ecosystems both directly by changing microbial physiology and indirectly by causing shifts in microbial community composition. Some of these warming‐driven changes are short term, but others may persist over time. Here, we took advantage of a long‐term (14 yr) warming experiment in a tallgrass prairie to tease apart the influence of short‐ and long‐term warming on litter decomposition. We collected soils originating from warmed and control plots and incubated them with a common litter substrate in a reciprocal design under elevated and ambient growth chamber temperatures. Litter decomposition was 40% higher in soils that were warmed in the field for 14 yr (long‐term warming) relative to soils derived from ambient plots. Short‐term warming in the laboratory had less of an impact on decomposition—decomposition increased by 12% under laboratory warming. Using a two‐pool soil carbon model to explore how different carbon pools may be responding, we found that long‐term warming accelerated the turnover of labile, not recalcitrant, carbon in these prairie soils—a result that is likely due to shifts in soil community activity/composition. Taken together, our results offer experimental evidence that warming‐induced changes in the soil community that occur over 14 yr of warming have long‐lasting effects on carbon turnover.

SF(6) has been widely used as an insulating and arc extinguishing medium in electric power equipments. Detection of gas decomposition products is an important means for condition monitoring and fault diagnosis. Trace H(2)O and O(2) have a significant influence on the species and concentrations of SF(6) decomposition products. It is important to explore the influence mechanism of trace H(2)O and O(2) on SF(6) decomposition products under arcing conditions. A series of SF(6) decomposition tests were carried out on a 40.5kV SF(6) circuit breaker, and a gas chromatograph and an electrochemical sensor were used to measure decomposed components. First, the H(2)O content remained constant, and the O(2) content and arcing energy changed in the tests. It has been found that the decomposition products of SF(6) are SOF(2), SO(2), CO, CO(2), CF(4), C(2)F(6) and C(3)F(8). Then, the O(2) content remained constant, and the H(2)O content changed. The decomposition products are mainly SOF(2), SO(2), CO and CO(2). Concentrations of all these decomposition products increase first and then tend to be stable slowly over time, but change differently with the increase of H(2)O and O(2) contents, because H(2)O and O(2) play different roles in the formation process of each decomposition characteristic components.

Abstract A primary goal of many next‐generation bioenergy systems is to increase ecosystem services such as soil carbon (C) storage and nutrient retention. Evaluating whether bioenergy management systems are achieving these goals is challenging in part because these processes occur over long periods of time at varying spatial scales. Investigation of microbially mediated soil processes at the microbe scale may provide early insights into the mechanisms driving these long‐term ecosystem services. Furthermore, seasonal fluctuations in microbial activity are rarely considered when estimating whole ecosystem functioning, but are central to decomposition, soil structure, and realized C storage. Some studies have characterized extracellular enzyme activity within soil structures (aggregates); however, seasonal variation in decomposition at the microscale remains virtually unknown, particularly in managed ecosystems. As such, we hypothesize that temporal variation in aggregate turnover is a strong regulator of microbial activity, with important implications for decomposition and C and nitrogen (N) storage in bioenergy systems. We address variation in soil microbial extracellular enzyme activity spatially across soil aggregates and temporally across two growing seasons in three ecosystems managed for bioenergy feedstock production: Zea mays L. (corn) agroecosystem, fertilized and unfertilized reconstructed tallgrass prairie. We measured potential N‐acetyl‐glucosaminidase (NAG), β‐glucosidase (BG), β‐xylosidase (BX), and cellobiohydrolase (CB) enzyme activity. Aggregate turnover in prairie systems was driven by precipitation events and seasonal spikes in enzyme activity corresponded with aggregate turnover events. In corn monocultures, soil aggregates turned over early in the growing season, followed by increasing, albeit low, enzyme activity throughout the growing season. Independent of management system or sampling date, NAG activity was greatest in large macroaggregates (>2000 μm) and CB activity was greatest in microaggregates (

Abstract Numerous studies link resource subsidies to consumers, yet manipulations of subsidy gradients are rare, limiting our ability to predict their effects. We measured natural abundance levels of the stable isotopes of carbon (δ13C) and nitrogen (δ15N) in consumers representing two taxonomic (invertebrates, fish) and multiple trophic groups (primary, secondary, and tertiary consumers) exposed to a gradient of Pacific salmon carcasses (0–4 kg/m2, eight treatment levels) in 16 experimental streams from September to December. We hypothesized (1) that consumer δ13C and δ15N values would increase with carcass loading and (2) that these relationships would vary among consumers and trophic levels. Within taxonomic groups, both δ13C and δ15N values increased with carcass loading indicating direct consumption of salmon organic matter (δ13C increase) and indirectly by consumption of salmon‐enriched prey (δ15N increase). The relative importance of these two pathways for invertebrates primary consumers varied with carcass loading, with an abrupt increase in direct consumption above ~0.5 kg/m2 salmon carcass wet mass. Both the rates of δ13C and δ15N increase and the shape of the response to the carcass gradient varied among invertebrates. The only fish that responded positively to carcasses was a small benthic, secondary consumer, and only for δ13C. Overall, benthic invertebrate primary consumers were the dominant pathway by which salmon organic matter entered the trophic system, followed by benthic secondary consumers, and then tertiary consumers (juvenile coho salmon and cutthroat trout) that occupy the water column. The attenuating response to subsidies at higher trophic levels was possibly due to a combination of low decomposition and metabolic rates during fall and winter, composition of the subsidy, and habitat use. Our results demonstrate that decomposing salmon carcasses provide variable but potentially important sources of C (range: ~0–60%) and N (range: ~0–35%) supporting benthic consumers during fall and winter, when environmental conditions constrain primary productivity, with some evidence of saturation at carcass loadings >0.1–0.6 kg/m2. Furthermore, stable isotope analysis showed that consumers exploited salmon organic matter in different ways, potentially alleviating competition and allowing for a more efficient processing of this resource subsidy.