Redistribution Of Nutrients Research Articles

Effects of cover on soil particle and associated soil nutrient redistribution on slopes under rainfall simulation

Purpose Sediment detachment, transportation, and deposition occurred alternately along slope during erosion process. Nutrients were mobilized with sediment movement. In this research, nutrients and fractal characteristics were analyzed on both bare and covered slopes. Then, combined with photogrammetry technique, soil elevation and associated soil nutrient redistribution on slope positions during rainfall event were explored.

Preface: Special Issue on Wildland Fires

Wildland fires are a critical Earth-system process that impacts human populations in each settled continent[...]

Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summer.

Phytoplankton biomass during the austral summer is influenced by freezing and melting cycles as well as oceanographic processes that enable nutrient redistribution in the West Antarctic Peninsula (WAP). Microbial functional capabilities, metagenomic and metatranscriptomic activities as well as inorganic 13C- and 15N-assimilation rates were studied in the surface waters of Chile Bay during two contrasting summer periods in 2014. Concentrations of Chlorophyll a (Chla) varied from 0.3 mg m-3 in February to a maximum of 2.5 mg m-3 in March, together with a decrease in nutrients; however, nutrients were never depleted. The microbial community composition remained similar throughout both sampling periods; however, microbial abundance and activity changed with Chla levels. An increased biomass of Bacillariophyta, Haptophyceae and Cryptophyceae was observed along with night-grazing activity of Dinophyceae and ciliates (Alveolates). During high Chla conditions, HCO3- uptake rates during daytime incubations increased 5-fold (>2516 nmol C L-1 d-1), and increased photosynthetic transcript numbers that were mainly associated with cryptophytes; meanwhile night time NO3- (>706 nmol N L-1 d-1) and NH4+ (41.7 nmol N L-1 d-1) uptake rates were 2- and 3-fold higher, respectively, due to activity from Alpha-/Gammaproteobacteria and Bacteroidetes (Flavobacteriia). Due to a projected acceleration in climate change in the WAP, this information is valuable for predicting the composition and functional changes in Antarctic microbial communities.

NANOAKVAHELAT GERMANIUM AFFECT ON THE GROWTH OF PIGLETS DURING THE PRENATAL PERIOD

NANOAKVAHELAT GERMANIUM AFFECT ON THE GROWTH OF PIGLETS DURING THE PRENATAL PERIOD

Sustained climate warming drives declining marine biological productivity.

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower-trophic-level productivity, decrease by more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.

Starving ocean productivity

Climate Change Projected increases in greenhouse gas emissions could suppress marine biological productivity for a thousand years or more. As the climate warms, westerly winds in the Southern Hemisphere will strengthen and shift poleward, surface waters will warm, and sea ice will disappear. Moore et al. suggest that one effect of these changes will be a dramatic decrease in marine biological productivity (see the Perspective by Laufkotter and Gruber). This decrease will result from a global-scale redistribution of nutrients, with a net transfer to the deep ocean. By 2300, this could drive declines in fisheries yields by more than 20% globally and by nearly 60% in the North Atlantic. Science , this issue p. [1139][1]; see also p. [1103][2] [1]: /lookup/doi/10.1126/science.aao6379 [2]: /lookup/doi/10.1126/science.aat0795

Woody shrubs increase soil microbial functions and multifunctionality in a tropical semi-arid grazing ecosystem

Woody encroachment is of global concern in arid and semiarid regions around the world. Due to reduction in grass (forage), woody encroachment is viewed as ecosystem disservice and degradation, even though this may not reduce ecosystem functions. Often, management perceptions of degradation remain inadequately informed by knowledge of ecosystem processes. We compared 11 biotic variables related to soil and microbial functions under shrubs against paired-adjacent grassland:- carbon, nitrogen, C:N ratio, organic matter, plant-available N, N-mineralization rate, microbial biomass C and N, basal respiration, and metabolic-quotient. We summarized these as a multifunction-index. We also measured five soil physico-chemical covariates:- pH, conductivity, bulk density, texture and water holding capacity. These 11 biotic variables were 15–48% higher under shrubs than under grass; multifunction-index was also higher (by 366%). After accounting for spatial autocorrelation and background differences in physico-chemical covariates (redundancy analysis), altered ecosystem functions were attributable to shrubs. Overall, shrubs can enhance ecosystem functions, and maintain important ecological processes through concomitant changes in soil physico-chemical properties. While shrubs should not be equated to ecological degradation, they present a challenging triage of ecosystem service, disservice, and function for grasslands. Management strategies could benefit from targeting patterns of nutrient re-distribution under shrubs.

Dissolution and redistribution of trace elements and nutrients during dredging of iron monosulfide enriched sediments

The increased use of estuarine waters for commercial and recreational activities is one consequence of urbanisation. Western Australia's Peel-Harvey Estuary highlights the impacts of urbanisation, with a rapidly developing boating industry and periodic dredging activity. The aim of this research is to evaluate the potential mobility of nutrients and trace elements during dredging, and the influence of flocculation on iron and sulfur partitioning in iron monosulfide enriched sediments. Our findings indicate a short-term increase in nitrate, phosphate and ammonium, during dredging through the resuspension of sediments. However, no increase in metal mobilisation during dredging was observed except copper (Cu) and zinc (Zn). Flocculant addition increased the release of nutrients, zinc (Zn) and arsenic (As) from sediments, had no effect on acid volatile sulfides and pyritic sulfur, but corresponded with an initial sharp rise in elemental sulfur concentrations. The run-off water from geofabric bags should be treated to decrease the concentrations of Zn and As to their background levels before releases into the estuary. Long-term impact of dredging on organic matter mineralisation and its subsequent effect on nutrients and trace elements dynamics needs further investigation.

Use of manure nutrients from concentrated animal feeding operations

Abstract Over the past few decades, there has been a nationwide trend away from small livestock farms and toward large Concentrated Animal Feeding Operations (CAFOs). This shift results in concentrated manure production and introduces potential problems associated with its disposal. We analyzed data from 13 permitted CAFOs in southeastern Michigan, including 1187 occurrences of manure application from 12 of the CAFOs with available field-level data. CAFOs applied excess manure nutrients to cropland by applying to fields with soil phosphorus test levels >50 ppm (42% of all cases), applying to soybeans (7% of all cases), over-estimating crop yields in calculating plant nutrient requirements (67% of all cases), and applying beyond what is allowed by state permits (26% of all cases). This represents significant potential for redistribution of manure nutrients. The total amount of manure from all instances of over-application could be redistributed to fertilize over 4775 ha (11,800 acres) per year. Significant barriers to redistribution of manure exist, however, including cost, land availability, crop and soil need, transport logistics, and farmers' reluctance to use manure instead of inorganic fertilizer due to its variable composition. These findings are relevant to the harmful algal bloom and hypoxia issues in Lake Erie, which are driven by excess nutrients, and can be used to better inform science, modeling, and policy in the region.

Response of foliar nutrients of Rubus allegheniensis to nutrient amendments in a central Appalachian hardwood forest

Abstract Foliar nutrient concentrations are often useful in inferring soil fertility and plant-soil interactions. This study examined pre- and post-senescent foliar macronutrients and Mn of Rubus allegheniensis to assess potential effects of two nutrient amendments on mineral soil nutrient availability in aggrading hardwood stands: additions of (NH4)2SO4 (simulating increases in acid deposition) and additions of (NH4)2SO4 with dolomitic limestone (simulating mitigation of effects of acidification). Foliar Mn analysis further addressed a prediction of the nutrient redistribution hypothesis, i.e., Rubus accumulates Mn in pre-senescent leaves and further concentrates Mn in post-senescent leaves to produce high-Mn litter. The study used a four plot × four block randomized design with three experimental treatments (Control, NS, NS + Lime). Rubus leaves were harvested randomly in plots of all treatment before and after senescence. Experimental treatments appeared to increase availability of N and P, with little effect on K. Simulated acidification decreased availability of Ca and Mg, an effect mitigated for Mg by addition of dolomitic limestone. By contrast, Mn in Rubus foliage was up to 100 times more concentrated than in most plant species, and was further concentrated by ∼60% during senescence. These latter observations support predictions of the nutrient redistribution hypothesis that Rubus redistributes Mn from the rooting zone to surface soil.

Evaluating the effect of nutrient redistribution by animals on the phosphorus cycle of lowland Amazonia

Abstract. Phosphorus (P) availability decreases with soil age and potentially limits the productivity of ecosystems growing on old and weathered soils. Despite growing on ancient soils, ecosystems of lowland Amazonia are highly productive and are among the most biodiverse on Earth. P eroded and weathered in the Andes is transported by the rivers and deposited in floodplains of the lowland Amazon basin creating hotspots of P fertility. We hypothesize that animals feeding on vegetation and detritus in these hotspots may redistribute P to P-depleted areas, thus contributing to dissipate the P gradient across the landscape. Using a mathematical model, we show that animal-driven spatial redistribution of P from rivers to land and from seasonally flooded to terra firme (upland) ecosystems may sustain the P cycle of Amazonian lowlands. Our results show how P imported to land by terrestrial piscivores in combination with spatial redistribution of herbivores and detritivores can significantly enhance the P content in terra firme ecosystems, thereby highlighting the importance of food webs for the biogeochemical cycling of Amazonia.

Swarming Behavior Emerging from the Uptake–Kinetics Feedback Control in a Plant-Root-Inspired Robot

This paper presents a plant root behavior-based approach to defining the control architecture of a plant-root-inspired robot, which is composed of three root-agents for nutrient uptake and one shoot-agent for nutrient redistribution. By taking inspiration and extracting key principles from the uptake of nutrient, movements and communication strategies adopted by plant roots, we developed an uptake–kinetics feedback control for the robotic roots. Exploiting the proposed control, each root is able to regulate the growth direction, towards the nutrients that are most needed, and to adjust nutrient uptake, by decreasing the absorption rate of the most plentiful one. Results from computer simulations and implementation of the proposed control on the robotic platform, Plantoid, demonstrate an emergent swarming behavior aimed at optimizing the internal equilibrium among nutrients through the self-organization of the roots. Plant wellness is improved by dynamically adjusting nutrients priorities only according to local information without the need of a centralized unit delegated for wellness monitoring and task allocation among the agents. Thus, the root-agents can ideally and autonomously grow at the best speed, exploiting nutrient distribution and improving performance, in terms of exploration capabilities and exploitation of resources, with respect to the tropism-inspired control previously proposed by the same authors.

Spatio-temporal variations of carbon and nitrogen in biogenic structures of two fungus-growing termites (M. annandalei and O. yunnanensis) in the Xishuangbanna region

Fungus-growing termites are abundant and play an important role in soil nutrient dynamics in the tropics due to their activities and unique effects on soil physical, chemical and biochemical properties. However, the mechanisms of termite mound turnover and the effects of such turnover on temporal and spatial patterns of nutrients in surrounding soils have rarely been studied. Here, we investigated the relationship between the stabilization and redistribution of soil nutrient properties and the chronological development of termite mounds (primary, secondary-occupied and abandoned mounds). The study was conducted to assess the concentrations of nutrients and water content in the biogenic structures produced by two fungus-growing termites (M. annandalei and O. yunnanensis) in different mound stages. Samples were collected along a transect at regular intervals proportional to the size of the biogenic structure. We found the concentration of NO3− in the following sequence: active mound, abandoned mound, and the surrounding soils. The concentrations of organic carbon (Corg) and total N in the active mounds were significantly lower than those in the surrounding topsoils, although a weak difference was observed with subsoils. The concentrations of Corg and total N in the abandoned mounds were significantly higher than those in active mounds, whereas no difference was observed with surrounding soils. The mean concentrations of nutrients were significantly different between fresh parts (sampling locations 1–3) and old parts (locations 4–6) of the secondary-occupied mounds. The nutrients in the fresh parts of the mound approached the values in the primary mound; whereas the nutrients in the old part of the mound approached the values in the abandoned mound. Our results indicate that nutrient concentrations change through the chronological development of termite mounds, which are hot spots of nutrients that subsequently affect ecosystem processes at specific spatial and temporal scales through the stabilization and redistribution of nutrients.

Intensified sweetpotato production in Papua New Guinea drives plant nutrient decline over the last decade

Sweetpotato (Ipomoea batatas) is the staple food of the Papua New Guinea Highlands and is primarily grown in swidden-type production systems. Because of high population growth and limited available land to expand agricultural production, land use must be intensified to ensure food security. In this study, changes in sweetpotato production systems were assessed by comparing field surveys conducted in 2005 and 2014. During the nine years between surveys, the length of fallow period decreased by 48%, from an average length of 12.1 in 2005 to 6.3 years in 2014. This reduction coincided with a reduced growth period for sweetpotato production gardens from 13.1 to 9.6 month (27%). The time required to reach gardens from the family home increased by 60% from 2005 to 2014. This surrogate measure shows that increasing land pressure has forced farmers to use more remote sweetpotato gardens. The clear driver for increased production was increased demand for sweetpotato as a cash crop; 83% more sweetpotato was sold, rather than consumed by the producer. Despite the increase in production, the management of soil fertility remained unchanged, and farmers continued not to use mineral fertilisers for sweetpotato production. The intensification of land use reduced the occurrence of traditional bush/tree fallow species, such as Casuarina oligodon, which were traditionally used as fallow species in the sweetpotato system, but have been replaced by food legumes, e.g., beans and peanuts. As a consequence of land use intensification, there was a clear decline in soil fertility, particularly for soil N, P, Fe, and Zn, and plant tissue concentrations of N, S, Ca, Fe and B. Given the present rate of population growth and limited land area available to expand, land use intensification will continue. Comparison of the two surveys reported here, indicated that nutrient rundown of the system is occurring. To prevent further depletion of soil nutrients, especially as further intensification of the system is anticipated, nutrient inputs to the sweetpotato production system will need to be increased. In the short to medium-term, this may be through landscape nutrient redistribution strategies such as mulching with organic matter from outside the garden area in a cut and carry or cut and place method, but in the longer-term we anticipate that high levels of production can only be sustained through the addition of mineral fertilisers.

The distribution of biogenic substances in waters of the North Atlantic

The article considers the main regularities of distribution of biogenic elements in accordance with the dissolved oxygen and hydrological characteristics of the marine environment. To study the spatial distribution of biogenic elements taken three main forms of substances in the marine environment: phosphates, nitrates, silicates. Because these compounds in ocean are crucial importance for the development of life. Shows the role of hydrodynamic factors that most significantly affect the distribution and redistribution of nutrients in the waters of the North Atlantic. Quantitative evaluation of the nutrient transport system of currents. The calculated weight amount of phosphates transported by the stream per unit time.

Vertically challenged: How disease suppresses Daphnia vertical migration behavior.

Parasitic infections are increasingly recognized as influential forces in the migratory behaviors of hosts ranging from butterflies to whales. In aquatic zooplankton, diel vertical migrations (DVMs) are among the most recurrent behaviors with implications for predator-prey interactions, nutrient cycling, and energy flow, yet how parasitism affects such migrations remains an open question. Here, we tested the effects of sporangia cluster disease (SCD) on DVM of the large-bodied Daphnia pulicaria, which is often considered a key component of lake food webs. By collecting depth-specific zooplankton samples across diel cycles, between years, and among lakes, we show that infection is associated with strong inhibition of host DVM; while all Daphnia tended to occur deeper during the day, uninfected Daphnia and especially gravid individuals migrated to shallower waters at night. In contrast, infected hosts-which could comprise 40% of the population-were more likely to remain deep regardless of time of day. Among infected hosts, the intensity of SCD (sporangia count per host) predicted the degree of DVM inhibition. These observations-coupled with lab-based assays showing that infected hosts exhibited fewer swimming movements and persisted at lower depths than uninfected conspecifics-suggest that parasite-induced inhibition of DVM is a "sickness behavior" resulting from increasing morbidity and energy depletion as the infection intensifies toward host death. Considering the importance of large-bodied Daphnia as regulators of water clarity and prey for fishes, parasite-induced alterations of host migratory behavior have broad potential to affect the redistribution of energy and nutrients within lake ecosystems.

Ants are the major agents of resource removal from tropical rainforests.

Ants are diverse and abundant, especially in tropical ecosystems. They are often cited as the agents of key ecological processes, but their precise contributions compared with other organisms have rarely been quantified. Through the removal of food resources from the forest floor and subsequent transport to nests, ants play an important role in the redistribution of nutrients in rainforests. This is an essential ecosystem process and a key energetic link between higher trophic levels, decomposers and primary producers.We used the removal of carbohydrate, protein and seed baits as a proxy to quantify the contribution that ants, other invertebrates and vertebrates make to the redistribution of nutrients around the forest floor, and determined to what extent there is functional redundancy across ants, other invertebrate and vertebrate groups.Using a large‐scale, field‐based manipulation experiment, we suppressed ants from c. 1 ha plots in a lowland tropical rainforest in Sabah, Malaysia. Using a combination of treatment and control plots, and cages to exclude vertebrates, we made food resources available to: (i) the whole foraging community, (ii) only invertebrates and (iii) only non‐ant invertebrates. This allowed us to partition bait removal into that taken by vertebrates, non‐ant invertebrates and ants. Additionally, we examined how the non‐ant invertebrate community responded to ant exclusion.When the whole foraging community had access to food resources, we found that ants were responsible for 52% of total bait removal whilst vertebrates and non‐ant invertebrates removed the remaining 48%. Where vertebrates were excluded, ants carried out 61% of invertebrate‐mediated bait removal, with all other invertebrates removing the remaining 39%. Vertebrates were responsible for just 24% of bait removal and invertebrates (including ants) collectively removed the remaining 76%. There was no compensation in bait removal rate when ants and vertebrates were excluded, indicating low functional redundancy between these groups.This study is the first to quantify the contribution of ants to the removal of food resources from rainforest floors and thus nutrient redistribution. We demonstrate that ants are functionally unique in this role because no other organisms compensated to maintain bait removal rate in their absence. As such, we strengthen a growing body of evidence establishing ants as ecosystem engineers, and provide new insights into the role of ants in maintaining key ecosystem processes. In this way, we further our basic understanding of the functioning of tropical rainforest ecosystems.

Plant–plant interactions scale up to produce vegetation spatial patterns: the influence of long‐ and short‐term process

AbstractVegetation spatial patterns emerge in response to feedback interactions between organisms and their environment, because of the redistribution of water and nutrients around the plant canopy or as a consequence of facilitation/competition interactions at the plant level, even in the absence of pre‐existing substratum heterogeneities. It has been suggested that changes in vegetation spatial patterns are a signal of transition shift in ecosystems. Understanding the factors that lead to aggregated spatial patterns and control the transition to random distributions requires that environmental and species information is taken into account. In this study, we investigated the relative contributions of aridity (a long‐term process), to which vegetation is adapted, and the area covered by bare soil (short‐term process) to plant–plant associations and their contribution to aggregated spatial patterns. The study was conducted in a gradient of aridity ranging from that in subalpine grassland habitats in the Pyrenees and Sierra Nevada mountains to that in the semiarid steppes of Cabo de Gata and the middle Ebro Valley in Spain. We compared sites that differed in aridity and a geophysical feature (north‐ vs. south‐facing slope). We observed that the relative contribution of aridity and bare soil to plant–plant facilitation and vegetation aggregation differed in subalpine and semiarid areas. Facilitation in subalpine habitats had a marked effect on aggregated spatial patterns, while aridity contributed to disruption of these patterns. Conversely, in semiarid habitats, the disruption of aggregated patterns was mainly promoted by an increase in bare soil area rather than in aridity. In semiarid habitats, the higher level of stress on south‐facing slopes increased facilitation interactions relative to north‐facing slopes, although this did not enhance the persistence of aggregated spatial patterns. We conclude that the use of aggregated spatial patterns as an indicator of ecosystem shift must distinguish and separately take account of long‐term processes to which vegetation adapt, and short‐term process.

Impacts of Nitrogen and Phosphorus: From Genomes to Natural Ecosystems and Agriculture

Nitrogen (N) and/or phosphorus (P) availability can limit growth of primary producers across most of the world’s aquatic and terrestrial ecosystems. These constraints are commonly overcome in agriculture by applying fertilizers to improve yields. However, excessive anthropogenic N and P inputs impact natural environments and have far-reaching ecological and evolutionary consequences, from individual species up to entire ecosystems. The extent to which global N and P cycles have been perturbed over the past century can be seen as a global fertilization experiment with significant redistribution of nutrients across different ecosystems. Here we explore the effects of N and P availability on stoichiometry and genomic traits of organisms, which, in turn, can influence: i) plant and animal abundances; ii) trophic interactions and population dynamics; and iii) ecosystem dynamics and productivity of agricultural crops. We articulate research priorities for a deeper understanding of how bioavailable N and P move through the environment and exert their ultimate impacts on biodiversity and ecosystem services.

Simulating field-scale variability and precision management with a 3D hydrologic cropping systems model

Effective variable-rate nitrogen (N) management requires an understanding of temporal variability and field-scale spatial interactions (e.g. lateral redistribution of nutrients). Modeling studies, in conjunction with field data, can improve process understanding of agricultural management. CropSyst-Microbasin (CS-MB) is a fully distributed, 3-dimensional hydrologic cropping systems model that simulates small (10 s of hectares) heterogeneous agricultural watersheds with complex terrain. This study used a highly instrumented 10.9 ha watershed in the Inland Pacific Northwest, USA, to: (1) assess the accuracy of CS-MB simulations of field-scale variability in water transport and crop yield in comparison to observed field data, and (2) quantify differences in simulated yield and farm profitability between variable-rate and uniform fertilizer applications in low, average and high precipitation treatments. During water years 2012 and 2013 (a “water year” refers to October 1st through the following September 30th, where a given water year is named for the calendar year on September 30th), the model simulated surface runoff with a Nash–Sutcliffe efficiency (NSE) of 0.7, periodic soil water content (comparison to seasonal soil core measurements) with a root mean square error (RMSE) ≤0.05 m3 m−3, and continuous soil water content (comparison to in situ soil sensors) at 15 of 20 microsites with NSE ≥0.4. The model predicted 2013 field variability in winter wheat yield with RMSE of 1100 kg ha−1. Simulated uniform N management resulted in 0–35 kg ha−1 greater field average yield in comparison to variable-rate management. The savings in fertilizer costs under variable-rate N management resulted in $23–$32 ha−1 greater field average returns to risk. This study demonstrated the capacity of CS-MB to further understanding of simulated and observed field-scale spatial variability and simulated crop response to low, medium and high annual precipitation.