Nutrient Addition Research Articles

Biotic and abiotic factors affecting soil microbial carbon use efficiency

Soil microbial carbon use efficiency (CUE) refers to the efficiency of microorganisms in converting absorbed carbon into their own biomass carbon. Soil microbial CUE is a key parameter to understanding the soil carbon cycle. Biotic and abiotic factors are widely considered to be important factors influencing CUE. However, the related underlying mechanisms remain unclear. This review elaborates on the concept of soil microbial CUE and the various approaches used for its measurement. We reviewed the effects of various abiotic factors, such as temperature, soil moisture, pH, nutrient addition, and substrate type, and biotic factors, such as microbial community structure and diversity, on CUE. Finally, we discussed the focus areas that future studies need to further explore. We hope this review can provide a comprehensive understanding of the factors impacting soil microbial CUE, which is a fundamental step to improving soil carbon storage capacity.

Effect of temperature, nutrients and growth rate on picophytoplankton cell size across the Atlantic Ocean.

The cell size of picophytoplankton populations affects their ecology and biogeochemical role, but how different environmental drivers control its variability is still not well understood. To gain insight into the role of temperature and nutrient availability as determinants of picophytoplankton population mean cell size, we carried out five microcosm experiments across the Atlantic Ocean (45°N-27°S) in which surface plankton assemblages were incubated under all combinations of three temperatures (in situ, 3°C cooling and 3°C warming) and two nutrient levels (unamended and addition of nitrogen and phosphorus). The overall range of variability in cell volume was 5-fold for Prochlorococcus, 8-fold for Synechococcus and 6-fold for the picoeukaryotes. We observed, in all the treatments and in the control, a consistent trend toward larger mean cell sizes over time for both Prochlorococcus and Synechococcus, which was likely the result of sample confinement. Changes in temperature and nutrient status alone did not cause clear changes in cell size, relative to the control, but the combination of warming and nutrient addition resulted in an increase in Prochlorococcus and Synechococcus cell size. The largest increases in cell volume were associated with slow or negative population net growth rates. Our results emphasize the importance of considering changes in biovolume to obtain accurate estimates of picophytoplankton biomass and suggest that the inverse relationship between growth rate and population mean cell size may be a general pattern in marine phytoplankton.

Soil available phosphorous and potassium stocks related to environmental properties, land uses and soils

Abstract Soil available phosphorus (SAP) and potassium (SAK) are indispensable for crops, and their stocks are important for food production needed for a growing global population. This study analysed 991 soil profiles across a large part of Romania covering forestland, grassland and cropland in almost all ecological regions. This study investigated SAP and SAK stocks for different soil depths and characterized their magnitude and variability within land uses under different environmental ecosystems, soil classes and soil types, for a better soil and land management under a temperate-continental climate. Cropland soils present the highest SAP and SAK stocks. Chernozems, Phaeozems and Vertosols possess the highest SAP and SAK stocks in Romania, representing the largest country's pool. Both SAP stocks and SAK stocks are significantly correlated with basic environmental properties, existing direct correlations between SAP, SAK, soil organic carbon (SOC) and total nitrogen (TN) stocks. For all land uses, SAP and SAK stocks correlated significantly and directly with each other, as well as with annual temperature, clay content, pH and sum of base cations, and inversely with altitude, slope and annual precipitation. The best predictive values using multiple regression models and basic environmental driving factors were found for forestland stocks of SAP and SAK, followed by grassland stocks, while the lowest prediction occurred for cropland stocks, probably due to the long-term additional nutrient input performed by farmers in cropland that changed the natural conditions otherwise present in grassland, and especially in forestland. Based on these results some management measures are discussed.

Analyzing the impact of phosphorous and nitrogen on Castanopsis sclerophylla early growth stages

Plant growth elements, particularly nitrogen (N) and phosphorus (P) are vital for their growth and development, particularly for understory vegetation and their excess limits the net productivity of terrestrial ecosystems. This study focuses on the understory vegetation responds and adaptation to key essential nutrients under changing climate scenarios in subtropical evergreen broad-leaved forests, still needs research attention. this, we set up an experiment taking four treatments in a 50-year-old Castanopsis sclerophylla secondary forest under (a) control (CK), (b) N, (c) P, and (d) combined N and P addition, applied to natural forest regeneration seedlings of C. sclerophylla attained similar growth parameters of diameter of 3 cm and 10 cm height. In addition, carbon, N, P, and non-structural carbohydrates (NSC) were determined through the anthrone colorimetric approach in different parts of seedlings. Results show that the combined N + P application enhanced the N and P by 14.48 %−140.55 % in the seedlings in both dry and wet seasons, respectively. However, during wet season, the content of NSC in the plant leaves significantly exceeded under P addition. Remarkably, CK showed increased P in the growing season but lower during the dry season. Furthermore, the root starch content of seedlings showed a significant increase under the application of N and P compared to combined N + P, ranging between 45.60 % and 58.70 %. Overall, the plant growth is attributed to N and P intake. The nutrient addition and seasonal variations have a coupled effect on seedling growth as proved in the in the natural open forest experiment. The study outcomes emphasize that the alterations in NSC allocation in the roots and leaves of C. sclerophylla seedlings under N + P addition could enhance their adaptation to future global climate changes, drought conditions, and high N concentrations.

Tree functional group mediates the effects of nutrient addition on soil nutrients and fungal communities beneath decomposing wood

Tree functional group mediates the effects of nutrient addition on soil nutrients and fungal communities beneath decomposing wood

Arctic's hidden hydrocarbon degradation microbes: investigating the effects of hydrocarbon contamination, biostimulation, and a surface washing agent on microbial communities and hydrocarbon biodegradation pathways in high-Arctic beaches

BackgroundCanadian Arctic summer sea ice has dramatically declined due to global warming, resulting in the rapid opening of the Northwest Passage (NWP), slated to be a major shipping route connecting the Atlantic and Pacific Oceans by 2040. This development elevates the risk of oil spills in Arctic regions, prompting growing concerns over the remediation and minimizing the impact on affected shorelines.ResultsThis research aims to assess the viability of nutrient and a surface washing agent addition as potential bioremediation methods for Arctic beaches. To achieve this goal, we conducted two semi-automated mesocosm experiments simulating hydrocarbon contamination in high-Arctic beach tidal sediments: a 32-day experiment at 8 °C and a 92-day experiment at 4 °C. We analyzed the effects of hydrocarbon contamination, biostimulation, and a surface washing agent on the microbial community and its functional capacity using 16S rRNA gene sequencing and metagenomics. Hydrocarbon removal rates were determined through total petroleum hydrocarbon analysis. Biostimulation is commonly considered the most effective strategy for enhancing the bioremediation process in response to oil contamination. However, our findings suggest that nutrient addition has limited effectiveness in facilitating the biodegradation process in Arctic beaches, despite its initial promotion of aliphatic hydrocarbons within a constrained timeframe. Alternatively, our study highlights the promise of a surface washing agent as a potential bioremediation approach. By implementing advanced -omics approaches, we unveiled highly proficient, unconventional hydrocarbon-degrading microorganisms such as Halioglobus and Acidimicrobiales genera.ConclusionsGiven the receding Arctic sea ice and the rising traffic in the NWP, heightened awareness and preparedness for potential oil spills are imperative. While continuously exploring optimal remediation strategies through the integration of microbial and chemical studies, a paramount consideration involves limiting traffic in the NWP and Arctic regions to prevent beach oil contamination, as cleanup in these remote areas proves exceedingly challenging and costly.

Exploring Effects of Nutrient Availability, Species Composition, Stand Age, and Mesofaunal Exclusion on Leaf Litter Decomposition in Northern Hardwood Forests

In northern hardwood forests, litter decomposition might be affected by nutrient availability, species composition, stand age, or access by decomposers. We investigated these factors at the Bartlett Experimental Forest in New Hampshire. Leaf litter of early and late successional species was collected from four stands that had full factorial nitrogen and phosphorus additions to the soil and were deployed in bags of two mesh sizes (63 µm and 2 mm) in two young and two mature stands. Litter bags were collected three times over the next 2 years, and mass loss was described as an exponential function of time represented by a thermal sum. Litter from young stands had higher initial N and P concentrations and decomposed more quickly than litter from mature stands (p = 0.005), regardless of where it was deployed. Litter decomposed more quickly in fine mesh bags that excluded mesofauna (p < 0.001), which might be explained by the greater rigidity of the large mesh material making poor contact with the soil. Neither nutrient addition (p = 0.94 for N, p = 0.26 for P) nor the age of the stand in which bags were deployed (p = 0.36) had a detectable effect on rates of litter decomposition.

Enhancing soil carbon in solar farms through active land management: a systematic review of the available evidence

Abstract Ground-mounted solar farms are becoming common features of agricultural landscapes worldwide in the move to meet internationally agreed Net Zero targets. In addition to offering low-carbon energy, solar farms in temperate environments can be purposely managed as grasslands that enhance soil carbon uptake to maximise their climate benefits and improve soil health. However, there is little evidence to date on the ecosystem effects of land use change for solar farms, including their impact on soil carbon storage and sequestration potential through land management practices. We review the latest evidence on the associations between grassland management options commonly adopted by solar farms in temperate regions (plant diversity manipulation, mowing, grazing, and nutrient addition) and soil carbon to identify appropriate land management practices that can enhance soil carbon within solar farms managed as grasslands. Soil carbon response to land management intervention is highly variable and context-dependent, but those most likely to enhance soil carbon accrual include organic nutrient addition (e.g., cattle slurry), low-to-moderate intensity sheep grazing, and the planting of legume and plant indicator species. Plant removal and long-term (years to decades) mineral fertilisation are the most likely to result in soil carbon loss over time. These results can inform policy and industry best practice to increase ecosystem service provision within solar farms and help them deliver net environmental benefits beyond low-carbon energy. Regular monitoring and data collection (preferably using standardised methods) will be needed to ensure soil carbon gains from land management practices, especially given the microclimatic and management conditions found within solar farms.

Effects of Microplastics, Fertilization and Pesticides on Alien and Native Plants.

Plastic mulches, fertilizers and pesticides have been extensively employed in agriculture to increase crop yields, though it has also led to the inadvertent accumulation of them over time. These accumulations have the potential to disrupt the soil ecological process and subsequently impact the plant community composition. Alien plants always benefit from environmental variability, thus whether the accumulation of fertilizer, plastic, and pesticide in soil promotes the dominance of alien plants in an invaded community. Here, five aliens and co-occurring natives were selected as study materials, and a full factorial experiment was conducted to answer this question. Our study found that microplastics promote the biomass production of native plants at higher nutrient availability while having marginal influence on growth of alien plants. Alien plants exhibited a lower root mass fraction (RMF) with increased nutrient availability and a higher specific leaf area (SLA) in response to the addition of nutrients and microplastics. Pesticide residues in the soil also significantly decreased the root mass fraction of three species, but there was no significant difference between the effects on alien and native species. Overall, our results revealed that alien species adjusted their functional traits more quickly, but native species gained more growth advantages in response to fertilization and microplastics.

Microbial carbon utilization in a boreal lake under the combined pressures of brownification and eutrophication: insights from a field experiment

AbstractClimate and land use changes can increase terrestrial runoff to aquatic systems, leading to brownification and eutrophication in northern boreal lakes. Brownification may boost bacterial respiration and production, while eutrophication can enhance primary production and algal blooms. However, their combined effects on basal producers and bacterial carbon utilization are less understood. This study explores the combined impacts of the two stressors: brownification and eutrophication on microbial dynamics in Lake Bolmen. Utilizing a field mesocosm experimental design, treatments received different combinations of organic matter (OM) and inorganic nutrients to simulate predicted future scenarios. Results showed that OM additions significantly increased bacterial production and respiration, regardless of nutrient additions. Nutrient additions enhanced bacterial production but did not affect respiration. Both nutrients and OM stimulated bacterial growth efficiency. Labile carbon from DOM was the main driver of higher bacterial respiration and short-term production increases. Fluorescence data indicated that the combination of brownification and eutrophication led to higher terrestrial DOM utilization than each stressor alone. The study suggests that future boreal lakes may become more heterotrophic, thus increasing CO2 release. These findings highlight the complex interactions between DOM and nutrients and underscore the importance of considering multiple stressors in lake management and mitigation strategies.

Continuous Biological Ex Situ Methanation of CO2 and H2 in a Novel Inverse Membrane Reactor (IMR)

A promising approach for carbon dioxide (CO2) valorization and storing excess electricity is the biological methanation of hydrogen and carbon dioxide to methane. The primary challenge here is to supply sufficient quantities of dissolved hydrogen. The newly developed Inverse Membrane Reactor (IMR) allows for the spatial separation of the required reactant gases, hydrogen (H2) and carbon dioxide (CO2), and the degassing area for methane (CH4) output through commercially available ultrafiltration membranes, enabling a reactor design as a closed circuit for continuous methane production. In addition, the Inverse Membrane Reactor (IMR) facilitates the utilization of hydraulic pressure to enhance hydrogen (H2) input. One of the process’s advantages is the potential to utilize both carbon dioxide (CO2) from conventional biogas and CO2-rich industrial waste gas streams. An outstanding result from investigating the IMR revealed that, employing the membrane gassing concept, methane concentrations of over 90 vol.% could be consistently achieved through flexible gas input over a one-year test series. Following startup, only three supplemental nutrient additions were required in addition to hydrogen (H2) and carbon dioxide (CO2), which served as energy and carbon sources, respectively. The maximum achieved methane formation rate specific to membrane area was 87.7 LN of methane per m2 of membrane area per day at a product gas composition of 94 vol.% methane, 2 vol.% H2, and 4 vol.% CO2.

Crabs as snake predators? An observation from southern Italy leading to a comprehensive review

The recent elevation of the Western Grass Snake, Natrix helvetica, from subspecies status prompted an assessment of its natural history and ecological traits compared to closely related species. We report an unusual predation attempt by the freshwater crab Potamon fluviatile on N. helvetica sicula from Sicily, indicating an ecological interaction previously overlooked in this species. The observation suggests that this crab may utilise snakes’ muscle tissue as an additional nutrient source. This predator-prey interaction, although probably rare, adds to the understanding of the dynamics between crabs and snakes, shedding light on their interaction in freshwater habitats. To provide context for our observation and highlight its rarity, we searched through scientific literature and online sources to generate a comprehensive review of the phenomenon that examines the predatory behaviour of crabs on snakes.

Using dredged sediments from Lake Taihu as a plant-growing substrate: Focusing on the impact of microcystins

Using dredged sediment as plant growth substrates is a promising way to deal with large amounts of excavated sediments. However, it is a big challenge to deal with various pollutants in sediments, among which microcystins (MCs) gained limited attention. In this study, sediments collected from Lake Taihu were mixed with agricultural soil at a 1:1 ratio to create various growing substrates for lettuce (Lactuca sativa L. var. ramosa Hort.). Results indicated that fresh weight and leaf area of lettuce increased in some sediment-amended treatments due to additional nutrients, but food quality was negatively affected by sediment amendment as suggested by the soluble sugar and Vitamin C levels. MCs were detected in all lettuce grown in sediment-amended substrates, particularly in treatments with sediments collected during the bloom. The highest MC contents were found in treatment amended with sediments collected from Meiliang Bay in August (88.6 μg kg−1 for MC-LR and 65.6 μg kg−1 for MC-RR). MC accumulation in lettuce and the associated human health risks were significant, especially in treatments with sediments from the bloom period. Ecological risk assessments revealed high RQ values, indicating potential harm to the soil ecosystem. This study underscores the importance of considering MC content in sediments when evaluating their use as growing substrates. The findings contribute to understanding the environmental and health implications of sediment reuse, offering insights for safer agricultural practices and sediment management.

Patterns of (micro)nutrient limitation across the South Pacific Ocean

Nutrient limitation regulates phytoplankton growth throughout much of the global ocean and its assessment is important for our understanding of future changes in ocean productivity. The South Pacific Ocean represents a vast region where limiting nutrients have so far been investigated with only a handful of experiments. Here we report the results of eleven nutrient addition bioassay experiments conducted across the South Pacific Ocean at ca. 30°S as part of the GEOTRACES GP21 expedition. Nitrogen addition alone stimulated chlorophyll-a accumulation at all sites, whilst increases were larger following supplementary addition of iron in the eastern and central basin, and phosphate in the western basin. Enhanced iron stress following nitrogen addition in the eastern and central basin further pointed towards ambient iron concentrations approaching co-limiting levels. The overall east-to-west shift in serial limiting nutrients from iron to phosphate was attributed to a broadscale east-west increase in iron availability relative to nitrogen.

Is enzymatic stoichiometry a reliable indicator of microbial limitations in carbon, nitrogen, or phosphorus?

The enzymatic stoichiometry approach is based on the assumption that the metabolic and stoichiometric requirements of soil microorganisms are reflected in the production of enzymes targeting specific nutrient resources, making enzyme activities a useful tool for assessing microbial nutrient limitations. In this approach, β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG) (occasionally combined with leucine aminopeptidase, LAP), and acid/alkaline phosphatase (AP) are used as proxies for the broader suite of enzymes responsible for catalyzing complex substrates containing carbon (C), nitrogen (N), and phosphorus (P), respectively, because these enzymes catalyze the terminal reactions that release products containing C, N, and P. The fundamental premise of the approach can thus be reformulated as follows: BG:NAG and BG:AP ratios reflect the relative limitations of C versus N and C versus P, respectively, with higher ratios indicating stronger C limitation. Previous meta-analyses have suggested that the enzymatic stoichiometry approach is unreliable, as N and P fertilization often leads to reduction in BG:NAG and BG:AP, respectively, contradicting the predictions of the approach. However, some researchers question the validity of assessing enzymatic stoichiometry after the artificial addition of nutrients via fertilizers. For providing more convincing evidence, this study conducted a meta-analysis to assess the impact of incorporating various C sources, largely representative of those found in natural ecosystems—glucose, cellulose, and plant residues—on the BG:NAG or BG:AP ratios. The results demonstrated that a considerable number of data points exhibited elevated values (i.e., C addition accelerated C limitations), undoubtedly contradicting the fundamental premise of the approach. These findings highlight the unreliability of enzymatic stoichiometry as an indicator of microbial nutrient limitation.

Evaluation of Integrated Anaerobic/Aerobic Conditions for Treating Dye-Rich Synthetic and Real Textile Wastewater Using a Soda Lake Derived Alkaliphilic Microbial Consortia

Textile industry wastewater (WW) has intense color, high chemical oxygen demand (COD), pH, and salinity, making it challenging for conventional treatment. Soda lakes, with high alkalinity and salinity, host diverse microbes capable of textile dye degradation. This study evaluated anaerobic/aerobic reactors using alkaliphilic microbial consortia from Lake Chitu, an Ethiopian soda lake, for treating synthetic and real textile WW. The experimental setup consisted of a first-stage anaerobic reactor followed by a second-stage aerobic reactor, operating continuously with a predetermined flow rate and hydraulic residence time. After evaluating synthetic WW, real textile WW was collected in two batches (rounds I and II). The treatment setup removed 99% of the dye color for synthetic WW, 98% for round I, and 96% for round II. COD removal was 87% for synthetic WW, 86% for round I, and 93.37% for round II. TKN removal reached 90% for synthetic WW, 91% for round I, and 96% for round II at a steady state. Residual COD and TKN values met the final effluent discharge standards. GC–MS and IR analyses revealed that dyes were broken down into intermediate organic compounds under anaerobic conditions and further degraded into smaller molecules under aerobic conditions. This integrated reactor approach effectively removes dyes and enhances COD and TKN removal. The study’s novelty lies in evaluating both synthetic and real textile WW using integrated reactors under alkaline conditions in a continuous process, inoculating alkaliphilic consortia, without pre-enrichment or external nutrient addition to real WW. The study provides insights into the effectiveness of alkaliphilic microbial consortia derived from soda lakes for treating textile WW using integrated reactor conditions. Reactor microbiome characterization is needed to further explore microbial diversity and community structure.

Seagrass space occupation efficiency is key for their role as ecosystem engineers and ecological indicators

Studies for the preservation of seagrass beds biotopes have met difficulties in establishing appropriate methods assessing their health. We tested the efficiency of space occupation by seagrasses scattered worldwide (dgrass index), which proved to be dependent on clonal growth form and morphometric plasticity. dgrass correlated with the above-ground to below-ground biomass ratio. However, the latter was misleading when high ratios resulted from low below-ground biomass. Nutrient Posphate-limitations were revealed in situations of theoretical Nitrogen-limitation. Enhanced nutrient supply benefitted seagrasses only up to a threshold after which it became detrimental. Better nurtured, healthier meadows with denser canopies increased the organic matter in the sediment and had associated greater abundances of benthic macrofauna. Hence, seagrass biotopes could benefit from moderate anthropogenic nutrient additions. However, organic matter above ≈6% and/or reduced riverine discharges (dams upstream and climate-change-related droughts) were detrimental to healthy meadows, jeopardizing ecosystem services such as macrofauna abundances and carbon sinks.

Sediment accretion and nutrient enrichment enhance the growth and vegetative propagation of Phalaris arundinacea growing within a Carex thunbergii stand.

Sediment accretion (burial) and nutrient enrichment may exert a synergistic influence on the growth and distribution of macrophytes in floodplain wetlands; however, this phenomenon has rarely been examined. In this study, we investigated the effects of sediment accretion and nutrient enrichment on the growth and vegetative propagation of Phalaris arundinacea within a Carex thunbergii stand (one P. arundinacea ramet within 25 C. thunbergii ramets) using a factorial sediment burial (0, 3, and 6 cm) and nutrient addition (low, medium, and high) experimental design. High sediment burial (6 cm) without nutrient addition decreased the aboveground and total biomass of C. thunbergii but did not affect P. arundinacea, indicating that P. arundinacea is more tolerant to sediment burial than C. thunbergii. Moderate sediment burial (3 cm) with nutrient addition enhanced the aboveground and total biomass of P. arundinacea but did not affect C. thunbergii, indicating that P. arundinacea may gain a growth advantage over C. thunbergii under moderate sedimentation. High sediment burial with nutrient addition increased the number of rhizomes and ramets produced by P. arundinacea but did not affect C. thunbergii, indicating that the relative abundance of P. arundinacea may increase within the Carex community under high sedimentation conditions. Based on these results, it can be concluded that an increased sedimentation rate facilitates the invasion of P. arundinacea into Carex grasslands, and this invasion is further enhanced by nutrient enrichment. Therefore, management measures should be taken to reduce the sediment load and nutrient input to prevent Carex grasslands invasion by P. arundinacea and maintain the ecological function of floodplain wetlands.

Phosphorus limitation regulates the responses of microbial carbon metabolism to long-term combined additions of nitrogen and phosphorus in a cropland

Microorganisms play central roles in the decomposition and retention of soil organic carbon (SOC), but how nutrient addition in intensively managed croplands influences microbial C metabolism remains uncertain. Here, we investigated the effects of coupled phosphorus (P) and nitrogen (N) additions on microbial respiration, growth rate, C use efficiency (CUE), and biomass turnover time in a continuously managed Zea mays cropland, by combining an 18-year field fertilization experiment with the 18O–H2O labeling approach. Results showed that adding P at 50 and 100 kg P ha−1, combined with 150 kg N ha−1, increased respiration by 109% and 50.7%, increased growth rate by 207% and 135%, and increased CUE from approximately 0.26 without P addition to around 0.33 and 0.35, respectively. Conversely, adding N at varying rates (0, 100, 150, and 250 kg N ha−1), combined with 50 kg P ha−1, generated variable responses. These findings underscore the significance of P as the primary limiting element for microbial metabolism in this system. Ecoenzyme stoichiometry analysis further revealed that P addition decreased microbial P vs. N limitation, as well as decreased relative C limitation. In total, changes in P vs. N limitation with P and N additions accounted for 39.6% of the variation in microbial respiration, and in conjunction with relative C limitation, co-explained 51.4% of variations in growth rate and 44.0% of variations in CUE. Furthermore, our investigation identified positive associations of CUE with the activities of N and P-acquiring enzymes, but not with SOC. These results demonstrate flexible responses of microbial C metabolism to long-term anthropogenic N and P additions, highlighting their dependence on soil nutrient limitation. Consequently, optimizing the P-to-N fertilization ratio to alleviate relative P and C limitations may maximize microbial C assimilation and SOC retention in agroecosystems.

Nitrogen and phosphorus additions affect fruiting of ectomycorrhizal fungi in a temperate hardwood forest

The functioning of mycorrhizal symbioses is tied to soil nutrient status, suggesting that nutrient availability should influence the reproduction of mycorrhizal fungi. To quantify the effects of nitrogen (N) and phosphorus (P) availability on ectomycorrhizal fungal fruiting, we collected >4000 epigeous sporocarps representing 19 families during the course of a season in a full factorial NxP addition experiment in six replicate forest stands. Nutrient effects on fruiting shifted as the season progressed, with early fruiting species responding more to P and late-fruiting species responding more to N. The composition of species fruiting in young successional forests differed more with nutrient addition than in mature forests. Sporocarp abundance and species richness were suppressed by N addition. This work shows that N and P availability affect ectomycorrhizal fungal fruiting, with these effects taking place within a context defined by stand age and the progression of fruiting across the season.