Nutrient Sequestration Research Articles

Nutrient sequestration potential of water primrose Ludwigia stolinefera (Guill. & Perr.) P.H. Raven: A strategy for restoring wetland eutrophication.

The current work investigates the capacity of the water primrose (Ludwigia stolinefera) to sequester inorganic and organic nutrients in its biomass to restore eutrophic wetlands, besides its nutritive quality as fodder for animals. The nutrient elements and nutritive value of the water primrose were assessed seasonally in polluted and unpolluted watercourses. The water primrose plants’ highest biomass was attained during summer; then, it was significantly reduced till it reached its lowest value during winter. In the polluted canal, the plant root and shoot accumulated higher contents of all nutrient elements (except Na and Mg) rather than in the unpolluted Nile. They accumulated most investigated nutrients in the growing season during summer. The shoots accumulated higher contents of N, P, Ca, and Mg than the root, which accumulated higher concentrations of Na and K. Therefore, summer season is the ideal time to harvest water primrose for removing the maximum nutrients for restoring eutrophic watercourses. The aboveground tissues had the highest values of ether extract (EE) during spring and the highest crude fibers (CF) and total proteins (TP) during summer. In contrast, the belowground tissues had the lowest EE, CF, and TP during winter. In spring, autumn, and winter seasons, the protein content in the grazeable parts (shoots) of the water primrose was within the range, while in summer, it was higher than the minimum requirement for the maintenance of animals. There was a decrease in crude fibers and total proteins, while an increase in soluble carbohydrates content in the below- and above-ground tissues of water primrose under pollution stress. The total protein, lipids, and crude fibers of the aboveground parts of water primrose support this plant as a rough forage.

Flexibility in the Critical Period of Nutrient Sequestration in Bumble Bee Queens.

SynopsisBumble bee queens undergo a nutrient storage period prior to entering diapause wherein they sequester glycogen and lipids that are metabolized during overwintering. In the laboratory under optimal food availability conditions, the majority of nutrients are sequestered during the first few days of adulthood. However, if food resources are scarce during this narrow window of time, wild queen bumble bees might be limited in their ability to obtain adequate food resources for overwintering. Here we used a laboratory experiment to examine whether queen bumble bees exhibit flexibility in the timing of pre-overwintering nutrient sequestration, by limiting their access to either nectar (artificial) or pollen, the two primary foods for bumble bees, for varying periods of time. In response to these treatments, we quantified queen survival, changes in weight, and glycogen and lipids levels. We found evidence that queens are able to recuperate almost entirely from food resource limitation, with respect to nutrient storage, especially when it is experienced for shorter durations (up to 6 days). This study sheds light on how bumble bee queens are impacted by food resource availability at a critical life stage.PortugueseAs abelhas rainhas do gênero Bombus armazenam nutrientes antes de entrarem em diapausa, sequestrando o glicogênio e os lipídios que serão metabolizados durante o inverno. Em condições ideais de disponibilidade de alimento no laboratório, a maioria dos nutrientes é sequestrada nos primeiros dias de vida adulta. No entanto, em condições de escassez de alimento na natureza, as rainhas podem sofrer limitações em sua capacidade de obter recursos para o inverno. Nesse contexto, em condições controladas, examinamos se as rainhas exibem variações no sequestro de nutrientes, limitando o acesso ao néctar (artificial) ou pólen, seus principais alimentos, em diferentes intervalos de tempo. Em resposta a esses tratamentos, quantificamos a taxa de sobrevivência das rainhas, as mudanças no peso e os níveis de glicogênio e lipídios. Encontramos evidências de que as rainhas são capazes de recuperar a capacidade de armazenar nutrientes quase inteiramente, especialmente em períodos mais curtos de escassez de alimento (até 6 dias). Este estudo lança luz sobre como as rainhas são afetadas pela variação na disponibilidade de recursos alimentares em um estágio crítico da vida.SpanishLas abejas reinas de generó Bombus, mejor conocidas como reinas de abejorro se someten a un período de almacenamiento de nutrientes antes de entrar en diapausa, en el cual secuestran glucógeno y lípidos que se metabolizan durante el invierno. En el laboratorio, en condiciones óptimas de disponibilidad de alimentos, la mayoría de los nutrientes se secuestran durante los primeros días de la edad adulta. Sin embargo, si los recursos alimenticios son escasos durante esta estrecha ventana de tiempo, las abejas reinas silvestres podrían verse limitadas en su capacidad para obtener recursos alimenticios adecuados para pasar el invierno. Aquí utilizamos un experimento de laboratorio para examinar si las abejas reinas exhiben flexibilidad en el momento del secuestro de nutrientes antes de la hibernación, al limitar su acceso al néctar (artificial) o al polen, los dos alimentos principales de los abejorros, durante períodos variables. En respuesta a estos tratamientos, cuantificamos la supervivencia de la reina, los cambios de peso y los niveles de glucógeno y lípidos. Encontramos evidencia de que las reinas pueden recuperarse casi por completo de la limitación de los recursos alimenticios, con respecto al almacenamiento de nutrientes, especialmente cuando se experimenta por períodos más cortos (hasta 6 días). Este estudio arroja luz sobre cómo las abejas reinas se ven afectadas por la disponibilidad de recursos alimenticios en una etapa crítica de la vida.

Winter cover crops as reservoirs of tobacco rattle virus (TRV) and hosts of root-lesion, root knot and stubby-root nematodes

A greenhouse pot study was conducted on four cover crops (annual ryegrass, perennial tetraploid ryegrass, winter wheat cv. ‘Caledonia’ and sorghum-sudangrass) and one rotation crop (sweet corn cv. ‘Sheba’) to compare the efficiency of these crop species as hosts of Paratrichodorus minor (Colbran) Siddiqi, and the ability of the nematodes to acquire tobacco rattle virus (TRV) from roots of infected plants and re-transmit it to healthy plants. P. minor reproduced rapidly on sorghum-sudangrass and sweet corn and re-transmitted the virus to indicator plants. Annual ryegrass, perennial ryegrass, and winter wheat cv. ‘Caledonia’, all of which re-transmitted TRV poorly in the greenhouse, were evaluated in two years of field studies for fall establishment and soil coverage, nutrient sequestration, effect on parasitic nematode populations and on subsequent potato crops. Annual ryegrass performed best overall in terms of establishment, ground cover, overwintering survival and foliar biomass production. None of the cover crops had a consistently significant effect on populations of parasitic nematodes in field plots, including Pratylenchus, Paratrichodorus, and Meloidogyne. Both ryegrass cover crops appeared to provide a favourable environment for survival of root knot nematodes (Meloidogyne spp.), although they are not considered to be hosts of this nematode. There was no difference in soil carbon, nitrogen or potato yield following any cover crop. Symptoms of corky ringspot were not observed in the field and TRV was not detected in potato plants by RT-PCR.

Rethinking the Ecosystem Functions of Dicranopteris, a Widespread Genus of Ferns.

Dicranopteris is an ancient and widespread genus of ferns in pantropical regions. Some species of the genus can form dense thickets, and dominate the understory, which are common and key species in tropical and subtropical ecosystems. However, they were mostly cut or burned in forest management because of forming dense thickets which were considered to interfere with forest regeneration and succession. In the current review, we argue that the Dicranopteris species which are able to rapidly colonize barren areas may contribute to ecosystem recovery, resistance to environmental stress, and succession control. Rapid colonization involves prolific spore production, rapid clonal growth, the generation of high surface cover, and the ability to fill gaps; stress resistance includes resistance to abiotic stress, and the ability to reduce soil erosion from rainfall, alien species invasion, and soil contamination and toxicity; and succession facilitation consists of carbon and nutrient sequestration in soil, moderation of the microclimate, alteration of the soil microbial and faunal communities, and determination of which plant species to be established in the next successional stage. All of these ecosystem functions may be beneficial to ecosystem resilience. We expect that the distribution of Dicranopteris will expand in response to global warming, changes in precipitation patterns, increases in soil pollution, deforestation, and land degradation. We recommend that Dicranopteris, as a pioneer fern and a valuable component of tropical and subtropical ecosystems, needs more attention in future research and better management practices to promote forest regeneration and succession.

Large-scale eelgrass transplantation: a measure for carbon and nutrient sequestration in estuaries

The accelerated global losses of seagrass meadows makes restoration increasingly important. This restoration study was conducted in a shallow Danish estuary and describes one of the rare examples of successful large-scale eelgrass Zostera marina restoration outside North America. A simplified 3-step site selection approach was successfully applied to locate an optimal site for large-scale transplantation. It consisted of (1) qualitative assessments of vegetation using aerial photos, (2) inspection of potential sites with assessments of stressor presence and potential growth conditions and (3) transplantation tests for a final assessment of site suitability and methodology. The large-scale transplantation was initiated at the test site with the highest shoot production. After transplantation, shoot densities developed rapidly, achieving a 70-fold increase in density after about 2 yr. A rapid edge expansion (0.32 m yr-1) of the transplanted area was detected using drone-based monitoring. Both the final shoot density and edge expansion were comparable to those of natural eelgrass patches in the estuary. Eelgrass-transplanted areas accumulated more fine sediment particles and organic C, N and P than adjacent unvegetated sediment. Burial of organic C, N and P in eelgrass-transplanted sediments was 33 ± 7.5, 6.6 ± 0.9 and 3.0 ± 0.5 g m-2 yr-1, respectively (mean ± SE). In addition, inorganic C and N were assimilated by eelgrass transplants at rates of 290 ± 22 and 12 ± 1.0 g m-2 yr-1, respectively. The results highlight that important ecosystem services are already restored 2 yr after successful eelgrass restoration.

Insights into the Application of Co-composting for Soil Nutrient Stability - A Review

The recycling of waste organic materials for energy and nutrient recovery has gained immense attention over all spheres of life especially during the past few years. There is an increasing trend of opting co-composting as a feasible technology for easy conversion of organic wastes into nutrient-rich manure. However, their success on direct field application still suffers from nutrient instability, volatility, pathogenic infection, etc., leading to the unprecedented nutrient loss and environmental contamination. Despite these limitations, co-composting offers a sustainable soil amending system whereby the bio-chemical ecology of the soil and crops can be synergistically preserved with enhanced productivity. In this review, a critical comparison is presented to comprehend the need for changing agricultural practices in view of modified soil nutrient dynamics by analyzing (i) the soil characteristics before sowing and after harvesting, (ii) the role of emerging wastes in composting processes, (iii) the methods of field application, and (iv) the agronomic characteristics of sugarcane crop in a composted soil. The study shows that the co-composting of sludge and agricultural waste resulted in maximum cane yield per hectare (150 to 315 tonnes). The sludge-based co-composting is found to retain soil nutrients for a prolonged duration thus promising nutrient sequestration and minimizing subsurface contamination.

Long-term soil organic carbon dynamics in temperate cropland-grassland systems

Increasing soil organic carbon (SOC) in agroecosystems enables to address simultaneously multiple goals such as climate change adaptation and mitigation as well as food security. As croplands are depleted in SOC, they offer a great potential to sequester atmospheric carbon (C). Nonetheless, croplands are still losing SOC under most of the current agricultural systems. Although many factors driving SOC dynamics have already been identified, their relative importance has not been quantified yet. Using one of the densest European soil monitoring networks with 250 sites established in western Switzerland, in the present study we (i) assessed long-term (over 30 years) SOC dynamics in croplands (CR), permanent grasslands (PG) and mountain pastures (MP), and (ii) prioritized the importance of land use, soil characteristics and sites conditions in driving SOC dynamics. The SOC levels in PG and MP were similar when clay content was accounted for, whereas CR were depleted in SOC by 3.9 mg C mg−1 clay as compared to PG. The majority (61 %) of CR had SOC:clay ratio below 1:10, but only 16 % of PG and MP sites reached this threshold. By contrast, soil organic matter stoichiometry (C:N:Porg ratios) was similar in CR and PG for comparable SOC content. The increase of C:Porg ratio with SOC content (dilution effect) and the high total P in CR and PG (legacy effect) indicate the possibility to sequester atmospheric C at reduced nutrient sequestration costs. SOC changes ranged from -0.61 to 1.32 mg g-1 soil yr−1 and were the highest in sites that experienced land-use changes. No PG were losing SOC, while CR sites exhibited both SOC gains and losses. Because of the predominance of the initial SOC content on SOC dynamics, land-use history must be accounted for when assessing the effect of management practices. The main manageable factors driving SOC dynamics were the time under temporary or permanent grasslands along with the soil total P. As PG already are rich in SOC and total P, organic amendments should be partly redirected to CR.

Biochar production: A sustainable solution for crop residue burning and related environmental issues

AbstractThe crop residue burning poses a threat to the environment and human health due to the emission of toxic gasses and particulate matter. This study examines the possibility of biochar production from corp residue and its utilization as a soil fertility enhancer and alternative fuel as a sustainable solution. The estimations of the total biochar production from major crop residues produced (wheat, rice, sugarcane, and maize) in India and the evaluation of its impact on CO2 sequestration potential, nutrient sequestration, and improvement in crop yield were made with the available data. The estimations indicate that the biochars produced from crop residue could have high carbon (45–83%), nutrients (N: 0.3–3.2 g/kg%, P: 0.1–7.99 g/kg and K: 2.64–224 g/kg), cation exchange capacity (10.9–97.3cmol/kg), water holding capacity (41–561%) with high heat value (15–28 MJ/kg). On applying crop residue derived biochar in soil, the revenue can be generated through CO2 sequestration ($0.29–3.63 million per year) and enhancement in crop productivity (0.02–0.94 million $/ha/year). The study advises that the production of biochar from crop residue could be beneficial not only for the environment but also for the farmers. Technological developments for biochar production at farmer levels are needed to discontinue the crop residue burning in India.

Depth-Dependent Variables Shape Community Structure and Functionality in the Prince Edward Islands.

Physicochemical variables limit and control the distribution of microbial communities in all environments. In the oceans, this may significantly influence functional processes such the consumption of dissolved organic material and nutrient sequestration. Yet, the relative contributions of physical factors, such as water mass variability and depth, on functional processes are underexplored. We assessed microbial community structure and functionality in the Prince Edward Islands (PEIs) using 16S rRNA gene amplicon analysis and extracellular enzymatic activity assays, respectively. We found that depth and nutrients substantially drive the structural patterns of bacteria and archaea in this region. Shifts from epipelagic to bathypelagic zones were linked to decreases in the activities of several extracellular enzymes. These extracellular enzymatic activities were positively correlated with several phyla including several Alphaproteobacteria (including members of the SAR 11 clade and order Rhodospirillales) and Cyanobacteria. We show that depth-dependent variables may be essential drivers of community structure and functionality in the PEIs.

Understanding stoichiometric mechanisms of nutrient retention in wetland macrophytes: stoichiometric homeostasis along a nutrient gradient in a subtropical wetland

Nutrient homeostasis relates ambient stoichiometric conditions in an environment to the stoichiometry of living entities of that ecosystem. Plant nutrient sequestration in wetland ecosystems is a key process for downstream water quality. However, few studies have examined stoichiometric homeostasis of aquatic vegetation despite the importance of stoichiometry to plant nutrient uptake efficiency. This study investigated stoichiometric homeostasis of dominant emergent and submerged aquatic vegetation (EAV and SAV, respectively) within two treatment flow-ways of Everglades Stormwater Treatment Area 2 (STA-2). These flow-ways encompass a large gradient in plant nutrient availability. This study hypothesizes that wetland vegetation is homeostatic relative to ambient nutrients and consequently nutrient resorption does not vary along the nutrient gradient. We developed a framework to investigate how vegetation uptake and resorption of nutrients contribute separately to homeostasis. Overall, we determined that the wetland vegetation in this study was non-homeostatic with respect to differential uptake of nitrogen (N) versus phosphorus (P). In EAV, P resorption was relatively high and N resorption was moderate, and resorption efficiency did not vary significantly along the gradient. In separating the proportional contribution of resorption and uptake to the degree of homeostasis, resorption did not affect overall homeostatic status in EAV.

Intraspecific competition reduces the quantity of excreted nutrients in tadpoles

Anuran larvae can form the largest animal biomass seasonally in freshwater environments, yet, they are still one of the least-studied taxa in terms of nutrient regeneration. The present study tested whether sympatric tadpoles regenerate nutrients at similar rates and ratios, and whether increased intraspecific competition (hereafter ‘competition’) alters patterns of excretion. We quantified rates and ratios of excretion (dissolved nitrogen (N) from ammonia, phosphorus (P) from total dissolved P, and N:P ratio) in three pond-dwelling Japanese tadpoles (Pelophylax nigromaculatus, Rhacophorus schlegelii, Hyla japonica), and tested the effect of competition on excretion in Pelophylax nigromaculatus and Rhacophorus arboreus. The three co-occurring species regenerated nutrients at different rates and ratios; H. japonica excreted nutrients and produced faecal pellets at the lowest rates. Inside field enclosures, increasing tadpole density reduced the quantity but not the quality of excretion by the tadpoles, suggesting higher nutrient sequestration, likely to maintain a stoichiometrically balanced growth under limited resources. Differences in rates and ratios of excretion have previously been shown to have various effects on community structure by affecting primary productivity, highlighting the importance of species identity and interactions on ecosystem function.

Microbial processing of plant remains is co-limited by multiple nutrients in global grasslands.

Microbial processing of aggregate-unprotected organic matter inputs is key for soil fertility, long-term ecosystem carbon and nutrient sequestration and sustainable agriculture. We investigated the effects of adding multiple nutrients (nitrogen, phosphorus and potassium plus nine essential macro- and micro-nutrients) on decomposition and biochemical transformation of standard plant materials buried in 21 grasslands from four continents. Addition of multiple nutrients weakly but consistently increased decomposition and biochemical transformation of plant remains during the peak-season, concurrent with changes in microbial exoenzymatic activity. Higher mean annual precipitation and lower mean annual temperature were the main climatic drivers of higher decomposition rates, while biochemical transformation of plant remains was negatively related to temperature of the wettest quarter. Nutrients enhanced decomposition most at cool, high rainfall sites, indicating that in a warmer and drier future fertilized grassland soils will have an even more limited potential for microbial processing of plant remains.

Phycoremediation coupled biomethane production employing sewage wastewater: Energy balance and feasibility analysis

In the present work Chlorella pyrenoidosa, Scenedesmus abundans and Anabaena ambigua have been evaluated for their biomass, phycoremediation efficiency and biomethane production potential by cultivating them in the primary treated sewage waste water (PTSWW) under controlled conditions. By the end of 25-day experiment, up to 52–88% reduction was observed in the nutrient concentration from the 3:1 ratio of PTSWW. Co-digestion of microalgal biomass (dry) with cow dung was performed to estimate biomethane potential. Biogas yield of 618–925 ml g−1 VS with 48–65% of methane content was obtained employing the microalgal species cultivated in PTSWW. Microalgae appeared notably competent at nutrient sequestration from PTSWW with significant microalgal biomass productivity for biogas production. Energy balance studies revealed the feasibility of coupling the remediation with energy generation. High photosynthetic rate and biomass generation ability along with nutrient confiscation supports employment of microalgae as a potential next generation biofuel source with waste management.

Emergence of Ferrichelatase Activity in a Siderophore-Binding Protein Supports an Iron Shuttle in Bacteria.

Siderophores are small-molecule high-affinity multidentate chelators selective for ferric iron that are produced by pathogenic microbes to aid in nutrient sequestration and enhance virulence. In Gram-positive bacteria, the currently accepted paradigm in siderophore-mediated iron acquisition is that effluxed metal-free siderophores extract ferric iron from biological sources and the resulting ferric siderophore complex undergoes diffusion-controlled association with a surface-displayed siderophore-binding protein (SBP) followed by ABC permease-mediated translocation across the cell envelope powered by ATP hydrolysis. Here we show that a more efficient paradigm is possible in Gram-positive bacteria where extracellular metal-free siderophores associate directly with apo-SBPs on the cell surface and serve as non-covalent cofactors that enable the holo-SBPs to non-reductively extract ferric iron directly from host metalloproteins with so-called “ferrichelatase” activity. The resulting SBP-bound ferric siderophore complex is ready for import through an associated membrane permease and enzymatic turnover is achieved through cofactor replacement from the readily available pool of extracellular siderophores. This new “iron shuttle” model closes a major knowledge gap in microbial iron acquisition and defines new roles of the siderophore and SBP as cofactor and enzyme, respectively, in addition to the classically accepted roles as a transport substrate and receptor pair. We propose the formal name “siderophore-dependent ferrichelatases” for this new class of catalytic SBPs.

Meshes in mesocosms control solute and biota exchange in soils: A step towards disentangling (a)biotic impacts on the fate of thawing permafrost

Environmental changes feedback to climate through their impact on soil functions such as carbon (C) and nutrient sequestration. Abiotic conditions and the interactions between above- and belowground biota drive soil responses to environmental change but these (a)biotic interactions are challenging to study. Nonetheless, better understanding of these interactions would improve predictions of future soil functioning and the soil-climate feedback and, in this context, permafrost soils are of particular interest due to their vast soil C-stores. We need new tools to isolate abiotic (microclimate, chemistry) and biotic (roots, fauna, microorganisms) components and to identify their respective roles in soil processes. We developed a new experimental setup, in which we mimic thermokarst (permafrost thaw-induced soil subsidence) by fitting thawed permafrost and vegetated active layer sods side by side into mesocosms deployed in a subarctic tundra over two growing seasons. In each mesocosm, the two sods were separated from each other by barriers with different mesh sizes to allow varying degrees of physical connection and, consequently, (a)biotic exchange between active layer and permafrost. We demonstrate that our mesh-approach succeeded in controlling 1) lateral exchange of solutes between the two soil types, 2) colonization of permafrost by microbes but not by soil fauna, and 3) ingrowth of roots into permafrost. In particular, experimental thermokarst induced a ~60% decline in permafrost nitrogen (N) content, a shift in soil bacteria and a rapid buildup of root biomass (+33.2 g roots m−2 soil). This indicates that cascading plant-soil-microbe linkages are at the heart of biogeochemical cycling in thermokarst events. We propose that this novel setup can be used to explore the effects of (a)biotic ecosystem components on focal biogeochemical processes in permafrost soils and beyond.

Winter cover crops effects on soil properties and sweet corn yield in semi‐arid irrigated systems

AbstractWinter cover crops (WCCs) can bolster agroecosystem services, including improving soil and crop yields. However, information is lacking about WCCs in irrigated crops in the semiarid climates of the southwestern United States. We chose three WCC species for their ecological attributes: hairy vetch (Vicia villosa, nitrogen fixation), rye (Secale cereale, nutrient sequestration; allelopathy), and mustard (Brassica juncea, biofumigant). Crops were planted in either monoculture or 2‐ and 3‐way combinations to evaluate agroecosystem services. Sweet corn (Zea mays L.) was planted approximately 2 wk after WCC termination. Neither monocultures nor mixtures consistently produced the most biomass, as WCC biomass production differed between site and year. The highest yielding cover crop was vetch (4302 kg ha−1) followed by mustard–vetch (3528 kg ha−1) and rye–vetch (3130 kg ha−1), all within the same site year, and rye (3016 kg ha−1) in another site year. Cover crops generally increased mean weight diameter of soil aggregates (a measure of dry soil aggregation) over time, with values nearly doubling in mustard–vetch and mustard–rye–vetch plots at one site. Wet aggregate stability increased by as much as 18% in mustard and 27% in mustard–vetch plots. Fertilizer requirements decreased compared to fallow plots in the second year in all WCC plots except for rye at one site, and vetch increased sweet corn yield compared to dry fallow plots in 1 yr by an average of 43.1%. These results demonstrate that WCCs can have positive effects on dry aggregate stability and potentially cash crop yield in irrigated, semiarid agroecosystems.

不同生态保护地植物特征和土壤性质的对比研究——以黑河中游湿地为例

PDF HTML阅读 XML下载 导出引用 引用提醒 不同生态保护地植物特征和土壤性质的对比研究——以黑河中游湿地为例 DOI: 10.5846/stxb201904070674 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41261047，41761043）；西北师范大学青年教师科研能力提升计划团队项目（NWNU-LKQN-17-7） Comparative study of plant characteristics and soil properties in different ecological protected areas: a case study of middle reaches of the Heihe River Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选择黑河中游张掖国家湿地公园和张掖黑河湿地国家级自然保护区为研究对象，对比分析了植物组成、物种多样性、植物生长状态、土壤养分、土壤理化性质及植物土壤间关系。结果显示：湿地公园的植物高度和土壤养分含量（有机碳、全氮、速效氮、全磷、速效钾）显著高于自然保护区，土壤理化性质含量（容重、pH）显著低于自然保护区，表明湿地公园有利于植物生长发育、土壤养分固存、改善土壤质地；自然保护区的植物科属种、多度、物种多样性（多样性指数、丰富度指数、均匀度指数）显著高于湿地公园，表明自然保护区有利于维持植物多样性；两种保护地中影响植物多样性的土壤因子不同，湿地公园物种多样性与土壤全磷和速效磷显著正相关，而自然保护区物种多样性与土壤盐分显著负相关。 Abstract:In this paper, the Zhangye National Wetland Park and the Zhangye Heihe Wetland National Nature Reserve in the middle reaches of the Heihe River were examined in order to compare plant composition, species diversity, plant growth status, soil nutrients, soil physical and chemical properties, and the relationship between vegetation characteristics and soil properties. The results showed that plant height and soil nutrient content (organic carbon, total nitrogen, available nitrogen, total phosphorus, available potassium) in the Wetland Park were significantly higher than those in the Nature Reserve, and the soil physical and chemical properties (bulk density, pH) were significantly lower than those in the Nature Reserve, indicating that the Wetland Park is more conducive to plant growth and development, soil nutrient sequestration, and improved soil texture. The genus, abundance, and species diversity (diversity index, richness index, evenness index) of plants in the Nature Reserve are significantly higher than those in the Wetland Park, indicating that the Nature Reserve is more favorable to maintaining plant diversity. The plant species diversity index of the Wetland Park was significantly affected by soil total phosphorus and available phosphorus. The species diversity index of the Nature Reserve was significantly affected by soil salinity, indicating that the soil factors affecting plant diversity in different conservation areas were different. 参考文献 相似文献 引证文献

Reprioritization of biofilm metabolism is associated with nutrient adaptation and long-term survival of Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHI) is a human-restricted pathogen with an essential requirement for heme–iron acquisition. We previously demonstrated that microevolution of NTHI promotes stationary phase survival in response to transient heme–iron restriction. In this study, we examine the metabolic contributions to biofilm formation using this evolved NTHI strain, RM33. Quantitative analyses identified 29 proteins, 55 transcripts, and 31 metabolites that significantly changed within in vitro biofilms formed by RM33. The synthesis of all enzymes within the tryptophan and glycogen pathways was significantly increased in biofilms formed by RM33 compared with the parental strain. In addition, increases were observed in metabolite transport, adhesin production, and DNA metabolism. Furthermore, we observed pyruvate as a pivotal point in the metabolic pathways associated with changes in cAMP phosphodiesterase activity during biofilm formation. Taken together, changes in central metabolism combined with increased stores of nutrients may serve to counterbalance nutrient sequestration.

Leaf litter identity alters the timing of lotic nutrient dynamics

Abstract The effects of resource quality on ecosystems can shift through time based on preferential use and elemental needs of biotic consumers. For example, leaf litter decomposition rates are strongly controlled by initial litter quality, where labile litter is processed and depleted more quickly than recalcitrant litters. We examined the effect of this processing continuum on stream nutrient dynamics. We added one of four different litter compositions differing in litter quality (cottonwood [Populus deltoides], labile; sycamore [Platanus occidentalis], recalcitrant; bur oak [Quercus macrocarpa], recalcitrant; and mixed [equivalent mixture of previous three species]) to 12 large (c. 20 m long, with riffle, glide and pool sections) outdoor stream mesocosms to assess the effect of litter species composition on whole‐stream nutrient uptake. Nutrients were dosed once weekly for 8 weeks to measure uptake of NH4–N, NO3–N, and PO4–P. We also measured changes in litter C, N, and P content on days 28 and 56 of the study. Nutrient uptake rates were highly variable, but occasionally very different among litter treatments (c. 5× between highest and lowest uptake rates by species). Uptake rates were generally greatest in cottonwood (labile) streams early in the study. However, during the last 4 weeks of the study, bur oak streams (recalcitrant) took up more nutrients than cottonwood streams, resulting in more cumulative NO3–N uptake in bur oak than in cottonwood streams. Cumulative NO3–N uptake was greater in mixed streams than expected (non‐additive) on two dates of measurement, but was generally additive. Changes in litter nutrient content largely corroborated nutrient uptake patterns, suggesting strong N immobilisation early in the study and some N mineralisation later in the study. P was strongly retained by most litters, but especially bur oak. Nutrient content of litter also largely changed additively, suggesting minimal evidence for non‐additive diversity effects on nutrient source/sink status. Our results demonstrate that litter species identity can have whole‐ecosystem effects on stream nutrient dynamics, with important implications for the form and fate of nutrients exported downstream. Further, diverse litter assemblages may serve as temporal stabilisers of ecosystem processes, such as nutrient sequestration, due to microbial nutrient requirements and differential decomposition rates, or the classic litter processing continuum.

Management effects on plant species composition and ecosystem processes and services in a nutrient-poor wet grassland

The effect of changing management practices, from a more intensive to a less intensive cutting regime with partial abandonment, on plant species composition, frequency, and abundance was determined for an oligotrophic wet grassland in the south Bohemia region of the Czech Republic using data from vegetation surveys conducted in 1965 (2–3 cuts per year) and 2013 (parts cut once per year, other portions abandoned). These data, coupled with nutrient data from a nearby wet grassland with similar species composition as well as data from the literature, were used to predict the possible effect of these vegetation changes on ecosystem processes and services. The former, more diverse Molinia caerulea-dominated state has been replaced by a less-diverse grassland dominated by clonal hemicryptophytes, such as Carex acuta. Partial restoration has been accomplished where mowing has been resumed. Using Ellenberg indicator values for moisture and nutrients, the present species composition indicates that the area has become wetter over time, likely due to management decisions made at the regional scale. Carbon and nutrient sequestration has likely been enhanced in the current state, while services linked to greater species diversity have likely suffered. Such tradeoffs in ecosystem services must be considered when deciding whether to restore the more diverse Molinia caerulea-dominated state. Decisions at the regional scale will also influence the ability of achieving a desired structure.