Affect Nutrient Dynamics Research Articles

Effect of plant-soil system on the restoration of community stability after wildfire in the northeast margin of Qinghai-Tibet plateau

Wildfires, as an environmental filter, are pivotal ecological disturbances that reshape plant communities and soil dynamics, playing a crucial role in regulating biogeographic patterns and ecosystem services. In this study, we aim to explore the effects of wildfires on forest ecosystems, specifically focusing on the plant-soil feedback mechanisms within the northeastern margin of the Qinghai-Tibet Plateau (QTP). Utilizing Partial Least Squares Path Modeling (PLS-PM), we investigated the interrelationships among soil physicochemical properties, enzyme activities, species diversity, and community stability at varying post-fire recovery stages (5, 15, and 23 years). Results indicated that in the early recovery stages, rapid changes in soil properties such as decreased pH (p < 0.001) and increased nutrient availability facilitate the emergence of early successional species with high resource utilization traits. As the ecosystem evolved toward a climax community, the soil and vegetation exhibit increased stability. Furthermore, soil enzyme activities displayed dynamic patterns that corresponded with changes in soil nutrient content, directly influencing the regeneration and diversity of plant communities. Importantly, our study documented a transition in the influence of soil properties on community stability from direct positive effects in initial recovery phases to negative impacts in later stages, while indirect benefits accrue through increased species diversity and enzyme activity. Vegetation composition and structure changed dynamically with recovery time during community succession. Plant nutrient absorption and accumulation affected nutrient dynamics in the soil, influencing plant regeneration, distribution, and diversity. Our results underscore the complex interactions between soil and vegetation that drive the recovery dynamics post-wildfire, highlighting the resilience of forest ecosystems to fire disturbances. This study contributes to the understanding of post-fire recovery processes and offers valuable insights for the management and restoration of fire-affected forest ecosystems.

Rainfall impacts on nonpoint nitrogen and phosphorus dynamics in an agricultural river in subtropical montane reservoir region of southeast China

The increased frequency and intensity of heavy rainfall events due to climate change could potentially influence the movement of nutrients from land-based regions into recipient rivers. However, little information is available on how the rainfall affect nutrient dynamics in subtropical montane rivers with complex land use. This study conducted high-frequency monitoring to study the effects of rainfall on nutrients dynamics in an agricultural river draining to Lake Qiandaohu, a montane reservoir of southeast China. The results showed that riverine total nitrogen (TN) and total phosphorus (TP) concentrations increased continuously with increasing rainfall intensity, while TN:TP decreased. The heavy rainfall and rainstorm drove more than 30% of the annual N and P loading in only 5.20% of the total rainfall period, indicating that increased storm runoff is likely to exacerbate eutrophication in montane reservoirs. NO3−-N is the primary nitrogen form lost, while particulate phosphorus (PP) dominated phosphorus loss. The main source of N is cropland, and the main source of P is residential area. Spatially, forested watersheds have better drainage quality, while it is still a potential source of nonpoint pollution during rainfall events. TN and TP concentrations were significantly higher at sites dominated by cropland and residential area, indicating their substantial contributions to deteriorating river water quality. Temporally, TN and TP concentrations reached high values in May-August when rainfall was most intense, while they were lower in autumn and winter than that in spring and summer under the same rainfall intensities. The results emphasize the influence of rainfall-runoff and land use on dynamics of riverine N and P loads, providing guidance for nutrient load reduction planning for Lake Qiandaohu.

Invasive species interactions affect nutrient cycling in a shallow reservoir: a mesocosm experiment

Shivers SD, Golladay SW, Waters MN, Wilde SB, Marzolf NS, Covich AP. 2023. Invasive species interactions affect nutrient cycling in a shallow reservoir: a mesocosm experiment. Lake Reserv Manage. 39:278–290.Nonnative species’ introductions can affect nutrient dynamics as new combinations of species form novel ecosystems. This experiment investigated how combinations of 3 invasive species, one submerged macrophyte (Hydrilla) and 2 benthic invertebrates (Corbicula and Pomacea), affected nutrient cycling in a shallow reservoir, Lake Seminole, Georgia, United States. To assess these effects, an in-reservoir mesocosm array was installed using different combinations of the invasive species. Eight physical and chemical parameters of water quality were measured in all the mesocosms (1 control, 7 treatments) weekly for the duration of the 5 wk experiment. Nitrogenous compounds were strongly affected by Hydrilla and Pomacea presence, with NO3-N concentrations decreasing in Hydrilla mesocosms and NH4-N and total nitrogen (TN) increasing in Pomacea mesocosms. Corbicula, when present, helped to mitigate increases in N concentrations, presumably as filter feeding reduced water column TN concentration. Overall, Hydrilla growth reduced inorganic N concentration. Pomacea grazing converted stored N to available organic and particulate N. Total phosphorus concentrations were not impacted by the invasive species treatments and increased in all mesocosms during the experiment. In short, Hydrilla and Corbicula are contributing to the uptake, conversion, and sequestration of nutrients that may increase eutrophication, while Pomacea is releasing potentially eutrophying nutrients. As climate change and human influence continue to create new combinations of species, it is important to understand the effects produced by novel combinations of species.

Climate change impacts on eutrophication in the Po River (Italy): Temperature-mediated reduction in nitrogen export but no effect on phosphorus

Rivers worldwide are under stress from eutrophication and nitrate pollution, but the ecological consequences overlap with climate change, and the resulting interactions may be unexpected and still unexplored. The Po River basin (northern Italy) is one of the most agriculturally productive and densely populated areas in Europe. It remains unclear whether the climate change impacts on the thermal and hydrological regimes are already affecting nutrient dynamics and transport to coastal areas. The present work addresses the long-term trends (1992–2020) of nitrogen and phosphorus export by investigating both the annual magnitude and the seasonal patterns and their relationship with water temperature and discharge trajectories. Despite the constant diffuse and point sources in the basin, a marked decrease (-20%) in nitrogen export, mostly as nitrate, was recorded in the last decade compared to the 1990s, while no significant downward trend was observed for phosphorus. The water temperature of the Po River has warmed, with the most pronounced signals in summer (+0.13°C/year) and autumn (+0.16°C/year), together with the strongest increase in the number of warm days (+70%–80%). An extended seasonal window of warm temperatures and the persistence of low flow periods are likely to create favorable conditions for permanent nitrate removal via denitrification, resulting in a lower delivery of reactive nitrogen to the sea. The present results show that climate change-driven warming may enhance nitrogen processing by increasing respiratory river metabolism, thereby reducing export from spring to early autumn, when the risk of eutrophication in coastal zones is higher.

Nutrient dynamics in water and soil under conventional rice cultivation in the Vietnamese Mekong Delta.

Background The evaluation of nutrient variability plays a crucial role in accessing soil potentials and practical intervention responses in rice production systems. Synthetic fertilizer applications and cultivation practices are considered key factors affecting nutrient dynamics and availability. Here, we assessed the nutrient dynamics in surface, subsurface water and soil under local water management and conventional rice cultivation practices in the Vietnamese Mekong Delta. Methods We implemented a field experiment (200 m 2) in the 2018 wet season and the 2019 dry season in a triple rice-cropping field. Eight samples of surface water, subsurface water (30-45 cm), and topsoil (0-20 cm) were collected and analysed during the rice-growing seasons. Results The results showed that N-NH 4 +, P-PO 4 3- and total P peaks were achieved after fertilizing. Irrespective of seasons, the nutrient content in surface water was always greater than that of subsurface water ( P < 0.001), with the exception of N-NO 3 -, which was insignificant ( P > 0.05). When comparing the wet and dry seasons, nutrient concentrations exhibited minor differences ( P > 0.05). Under conventional rice cultivation, the effects of synthetic fertilizer topdressing on the total N, soil organic matter (SOM), and total P were negligible in the soil. Higher rates of N fertilizer application did not significantly increase soil N-NH 4 +, total N, yet larger P fertilizer amounts substantially enhanced soil total P ( P < 0.001). Conclusions Under conventional rice cultivation, N-NH 4 +, P-PO 4 3- and total P losses mainly occur through runoff rather than leaching. While N-NO 3 - loss is similar in surface water and subsurface water. Notably, nutrient content in soil was high; whilst SOM was seen to be low-to-medium between seasons. Future work should consider the nutrient balance and dynamic simulation in the lowland soil of the Vietnamese Mekong Delta's paddy fields.

Diet consistency but large-scale isotopic variations in a deep-sea shark: The case of the velvet belly lantern shark, Etmopterus spinax, in the northeastern Atlantic region and Mediterranean Sea

Deep-sea elasmobranchs are commonly reported as bycatch of deep-sea fisheries and their subsequent loss has been highlighted as a long-running concern to the ecosystem ecological functioning. To understand the possible consequences of their removal, information on basic ecological traits, such as diet and foraging strategies, is needed. Such aspects have been widely studied through stomach content analysis but the lack of long-term dietary information requires other tools to be used such as stable isotopes. This study examines nitrogen and carbon isotope compositions of the velvet belly lantern shark, Etmopterus spinax, one of the most impacted shark species in northeastern Atlantic fisheries as a result of accidental catches. E. spinax was sampled at four different locations, characterized by contrasting oceanographic and ecological conditions: the western Mediterranean Sea (near the Balearic Islands), the southern Iberian upwelling system, Rockall Trough and southwestern Norwegian fjords. Stomach content analysis revealed similar prey species among sites, with a diet dominated by Euphausiacea (mostly Meganyctiphanes norvegica) and an ontogenetic shift towards small teleost fishes, cephalopods or other crustaceans. Despite these similarities, muscle stable isotope compositions differed across sampled locations. Rather than clear dietary differences, the contrasted isotopic values are likely to reflect differences in environmental settings and biogeochemical processes affecting nutrient dynamics at the base of the food webs.

Spatial and Temporal Patterns in Carbon and Nitrogen Inputs by Net Precipitation in Atlantic Forest, Brazil

Abstract Understanding both carbon and nitrogen temporal and spatial inputs by rainfall in tropical forests is critical for proper forest conservation and management and might ultimately elucidate how climate change might affect nutrient dynamics in forest ecosystems. This study aimed to quantify the net precipitation contribution to the Atlantic Forest’s total carbon (C) and total nitrogen (N), identifying potential differences between these inputs regarding temporal (seasonal and monthly) and spatial scales. Rainfall samples were collected before and after interacting with the forest canopy from May 2018 to April 2019. The rainfall was enriched after crossing the forest canopy. Significant differences were found for gross rainfall and net precipitation between annual carbon (104.13 kg ha−1 and 193.18 kg ha−1) and nitrogen (16.81 kg ha−1 and 36.95 kg ha−1) inputs, respectively. Moreover, there was seasonal variability in the C and N inputs with 75% occurring in the wet season. Overall, the spatial patterns revealed that the same locations had the highest inputs regardless of the analyzed period. The forest-rainfall interactions provide constant C and N inputs, especially in the wet season, and are fundamental for the maintenance of ecological processes.

Responses of coastal sediment phosphorus release to elevated urea loading

Increased urea is one of the common nitrogen forms polluting coastal waters and affecting nutrient dynamics. To investigate the effects of urea on sediment phosphorus (P) release, we carried out a 2-month mesocosm experiment with six targeted loadings of urea (0–0.6 mg N L−1 d−1). Results showed that: i) urea was rapidly transformed into ammonium and then nitrate (NO3−). ii) When nitrogen occurred as urea or ammonium, minor P release was observed. iii) After urea were mostly converted to NO3−, P release became clearer. iv) NO3− had a dual effect by promoting P release through decreasing sediment pH and increasing alkaline phosphatase activity or by inhibiting P release through improving sediment oxidation. v) The overall effects of urea on P release depended on the ultimate NO3− concentrations, being prominent when NO3− ≥ 11 mg N L−1. Our findings are of relevance when determining nitrogen reduction targets needed for combating eutrophication.

Nutrient dynamics in water and soil under conventional rice cultivation in the Vietnamese Mekong Delta

Background The evaluation of nutrient variability plays a crucial role in accessing soil potentials and practical intervention responses in rice production systems. Synthetic fertilizer applications and cultivation practices are considered key factors affecting nutrient dynamics and availability. Here, we assessed the nutrient dynamics in surface, subsurface water and soil under local water management and conventional rice cultivation practices in the Vietnamese Mekong Delta. Methods We implemented a field experiment (200 m 2) in the 2018 wet season and the 2019 dry season in a triple rice-cropping field. Eight samples of surface water, subsurface water (30–45 cm), and topsoil (0–20 cm) were collected and analysed during the rice-growing seasons. Results The results showed that N-NH 4+, P-PO 43- and total P peaks were achieved after fertilizing. Irrespective of seasons, the nutrient content in surface water was always greater than that of subsurface water (P&lt;0.001), with the exception of N-NO 3-, which was insignificant (P&gt;0.05). When comparing the wet and dry seasons, nutrient concentrations exhibited minor differences (P&gt;0.05). Under conventional rice cultivation, the effects of synthetic fertilizer topdressing on the total N, soil organic matter (SOM), and total P were negligible in the soil. Higher rates of N fertilizer application did not significantly increase soil N-NH 4+, total N, yet larger P fertilizer amounts substantially enhanced soil total P (P&lt;0.001). Conclusions Under conventional rice cultivation, N-NH 4+, P-PO 43- and total P losses mainly occur through runoff rather than leaching. While N-NO 3- loss is similar in surface water and subsurface water. Notably, nutrient content in soil was high; whilst SOM was seen to be low-to-medium between seasons. Future work should consider the nutrient balance and dynamic simulation in the lowland soil of the Vietnamese Mekong Delta’s paddy fields.

Patterns of Nutrient Dynamics within and below the Rootzone of Collard Greens Grown under Different Organic Amendment Types and Rates

The knowledge about nutrient dynamics in the soil is pivotal for sustainable agriculture. A comprehensive research trial can retort unanswered questions. Dynamics of nutrients sourced from organic amendment types (chicken manure, dairy manure, and MilorganiteTM) applied at different rates (0, 168, 336, 672 kg total N/ha) were monitored within and below the rootzone of collard greens cultivated on a sandy loam soil in Prairie View, TX, USA. Macro- and micronutrients (e.g., TN: total nitrogen, P: phosphorous, K: potassium, Na: sodium, Ca: calcium, Mg: magnesium, B: boron, Cu: copper, Fe: iron, and Zn: zinc) were analyzed from soil solution samples collected during six sampling periods from within and below the rootzone. As hypothesized, the organic amendment types and rates significantly (p &lt; 0.05 and/or 0.01) affected nutrient dynamics within and below the crop rootzone. Chicken manure released significantly more TN, P, K, Na, Ca, Mg, B, Cu, and Fe than the other two amendments. The application of chicken manure and MilorganiteTM resulted in higher below-the-rootzone leachate concentration of TN, Na, Mg, and Ca than in the leachates of dairy manure. Dairy manure treatments had the lowest concentrations of TN, Ca, and Mg; whereas, MilorganiteTM had the lowest concentrations of P, K, Na, B, and Cu in the collected leachates. The higher level of P (i.e., 4% in MilorganiteTM as compared to 2 and 0.5% in chicken and dairy manures, respectively, might have reduced the formation of Vesicular-Arbuscular (VA) mycorrhizae—a fungus with the ability to dissolve the soil P, resulting in slow release of P from MilorganiteTM treatment than from the other two treatments. Patterns of nutrient dynamics varied with rain and irrigation events under the effects of the soil water and time lapse of the amendment applications’ rates and types. All the macronutrients were present within the rootzone and leached below the rootzone, except Na. The dynamic of nutrients was element-specific and was influenced by the amendments’ type and application rate.

Forage legumes from the Mediterranean Fynbos biome of South Africa with potential for domestication: slope aspect affects tissue fibre and mineral composition

Fabaceae plants contribute greatly to a high quality of pasture in rangelands, because of high levels of protein in their tissues. Despite this established importance, only a few southern African legumes have been evaluated for nutritional value and domestication. The Overberg renosterveld vegetation of the Fynbos biome occupies undulating landscapes that have multiple slope aspects, creating variable microclimatic conditions affecting nutrient dynamics, species richness and plant chemical compositions. We assessed the effect of slope aspect on fiber and mineral composition of forage species present to provide information on the importance of slope for species characterization and nutritional value for domestication. Tissue samples from six replicates of the same species occurring on opposing aspects were collected for nutritional assessment. Results on the data showed that fibre and mineral composition differed in species occurring on different slopes, albeit with few exceptions. The concentrations of P, K and Mg in some species were significantly higher on the cooler and wetter south facing slopes relative to north facing slopes. Nutrient elements in soil samples collected from each site varied with slope aspects and elements. It is recommended that topography should be considered when studying forage nutritional assessments as part of future domestication programs.

Soil application of fungicides affects nutrient dynamics in ‘Blood Red’ sweet orange

Infected and damaged root system of sweet oranges (Citrus sinensis Osbeck L.) budded on rough lemon (Citrus jambheri Lush.) in Punjab-Pakistan has been suspected to affect nutrient uptake due to rootstock susceptibility to soil born fungal diseases. The experiment was performed on 12-15 years old ‘Blood Red’ sweet orange ‘Blood Red’) trees of uniform size and vigour at the Fruit Garden Sq. 9, Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Punjab, Pakistan. This study was conducted for consecutive two years. The objective of the research was to introduce sweet oranges in the main streamline of the citrus industry by improving their root health through fungicides treatments ultimately enhancing mineral nutrient uptake from the soil. The experiment was laid out according to Randomized Complete Block Design (RCBD) replicated thrice, taking a single tree as a treatment unit. The fungicides used in the experiment were Metalaxyl Mencozeb (Ridomil Gold), Fosetyl-Al (Alliette) and copper sulphate (CuSO4), in different combinations. Nutritional status of tree leaf macronutrients (N, P and K) and micronutrients (Mg, Fe, Mn, Cu and Zn) during flowering and final fruit set was evaluated at fortnight intervals with respect to different treatments. The different treatments enhanced nutrient uptake through roots and improved health and vigour of trees. It was more evident from the improvement of fruit quality and yield of treated trees compared with control. Although fungal analysis could not be performed, the improvement in general health and vigour of trees lead to the conclusion that root health was improved substantially. It might be concluded from this study that best orchard management emphasizing improvement in the root health could enhance the yield and quality of sweet oranges.

Soil and Plant Nutrient Dynamics in Response to Manuring with Different Organic Wastes under Alkaline Conditions

Manuring with organic wastes might be an important approach for maintaining soil fertility and crop productivity. However, beneficial effects of manuring may vary depending upon the type of manure and rate of application. The present study was planned to investigate the efficiency of three different manures i.e. pressmud, farmyard manure and chicken manure applied at 2.5%, 5%, 7.5% and 10% (w/w) to affect nutrient dynamics in soil and maize (Zea mays L) under alkaline conditions. Results revealed that manuring with organic wastes markedly affected the soil properties, with highest effect in case of chicken manure. Soil nutrient concentrations improved by the use of organic manures and maximum increase was found with pressmud which was 17.83%, 37.60%, 48.33% and 55.29% in phosphorus (P) and 9.82%, 20.54%, 32.14% and 40.18% potassium (K) at 2.5%, 5%, 7.5% and 10%, respectively compared to control, while farmyard manure showed superiority for soil nitrogen (N). Soil micronutrients including copper, iron, zinc and manganese were also greatly affected in response to manuring. Nutrient concentrations of maize were also enhanced by the use of manures, with maximum increase in case of pressmud which was 66.96, 77.68, 93.75 and 113.39% in N, 72.73, 154.55, 218.18 and 336.36% P, and 19.75, 30.86, 49.38 and 72.84% K at 2.5%, 5%, 7.5% and 10% (w/w), respectively compared to control. Similar trend was found in case of other nutrients. Pressmud again showed its superiority to improve grain yield i.e. 14.85%, 22.19%, 34.02% and 58.25% by the application of 2.5%, 5%, 7.5% and 10% (w/w), respectively compared to control. In conclusion, pressmud showed supremacy over other manures in improving soil properties and nutrient dynamics in soil and maize plants with a consequential increase in grain yield. The beneficial effects of manuring increased with increasing the application rate.

Respective contribution of urban wastewater and mangroves on nutrient dynamics in a tropical estuary during the monsoon season

Estuaries of Southeast Asia are increasingly impacted by land-cover changes and pollution. Here, our research objectives were to (1) determine the origins of nutrient loads along the Can Gio estuary (Vietnam) and (2) identify the processes that affect the nutrient pools during the monsoon. We constructed four 24-h time-series along the salinity gradient measuring nutrient concentrations and stable isotopes values. In the upper estuary, urban effluents from Ho Chi Minh City were the main input of nutrients, leading to dissolved oxygen saturation <20%. In the lower estuary, ammonium and nitrite concentration peaks were explained by mangrove export. No contribution from aquaculture was detected, as it represents <0.01% of the total river discharge. Along the salinity gradient, nutrient inputs were rapidly consumed, potentially by phytoplankton while nitrate dual-stable isotopes indicated that nitrification occurred. Thus, even in a large and productive estuary, urban wastewater can affect nutrient dynamics with potentially important ecological risks.

Geographical variation in Japanese cedar shapes soil nutrient dynamics and invertebrate community

The aim of this study was to examine whether differences in the provenances of canopy tree species affect the community of soil invertebrates. We used a common garden, where Cryptomeria japonica trees (Yoshino, Yanase, Itoshiro and Yaku) from four provenances were planted separately in each plot. In these plots, we measured the concentration of nutrients in leaves, litter and roots; Sr isotope ratio (87Sr/86Sr) of leaves; root exudation rate of organic acids; exchangeable nutrients in soil and soil parameters such as soil pH; and abundance and composition of soil invertebrates. Some parameters that may affect nutrient dynamics (concentration of nitrogen in roots, root exudation rate of organic acids, tree growth) and concentrations of calcium and phosphorus in leaves and soil were significantly higher in the Yoshino plot than in the other plots. The 87Sr/86Sr of leaves suggested that the cycling of nutrients such as calcium differed significantly between the plots. Furthermore, the abundances of soil invertebrates that are likely to be affected by nutrient concentrations (e.g. soil crustaceans) were significantly higher in the Yoshino plot than in the other plots. The effects of the provenance of a canopy tree species shape the soil invertebrate abundances and composition by altering the concentration of nutrients in the soil.

Nutrient availability affects the prevalence of a microsporidian parasite.

Defining the relationship between nutrients and parasitism is complicated by shifts in host physiology and population density, which can both mediate the effects of host diet on parasites and vice versa. We examined the relationship between nutrient availability and an abundant parasite capable of both horizontal and vertical transmission (Hamiltosporidium tvaerminnensis) of a planktonic crustacean, Daphnia magna, in rock pools on Baltic Sea Skerry islands. We found that the relative availability of nutrients directly affected infection prevalence; parasite prevalence was higher in pools with higher particulate N:P ratios. Infection prevalence was not related to Daphnia population densities. A complementary experiment that examined host responses to an N:P gradient in mesocosms indicated that high N:P ratios can increase spore load in the hosts. We surmise that high N:P food increases Daphnia feeding rate, which increases their contact with parasite spores and leads to higher prevalence and more intense infections. We found no direct evidence that parasite-induced changes in host nutrient use affected nutrient dynamics in pools. However, the relationship between diet N:P and the parasite's prevalence and load is consistent with previously documented patterns of this parasite's effect on host nutrient use. Taken together, this study suggests that high N:P ratios in food may benefit the parasite in multiple ways and could create environments that favour horizontal transmission over vertical transmission for parasites capable of both transmission routes. If so, nutrient limitation could have long-term consequences for host-parasite evolution.

Modelling of mangrove annual leaf litterfall with emphasis on the role of vegetation structure

Understanding local patterns of species-specific litterfall can help predict spatial differences in the amount and quality of organic matter input to systems under different environmental conditions. However, little is known about the drivers of differences in litterfall production in mangroves. Here we combined data from leaf litterfall (LL) studies (n = 13) and floristic studies (n = 16) conducted in the mangroves of the Ajuruteua peninsula (North of Brazil), at sites composed mainly of Rhizophora mangle and/or Avicennia germinans. We investigated the relationship between LL and vegetation parameters (height, diameter, basal area, density, and relative density) using partial least-squares regressions (PLS-R), building four models with different combinations of these parameters. Vegetation parameters explained 69–85% of the annual LL of A. germinans and 50–66% of R. mangle. Relatively strong, univariate significant relationships were also found between basal area and A. germinans LL (R2 = 0.40), and between height and R. mangle LL (R2 = 0.41). Nonetheless, models with four to five predictors yielded better fits. To illustrate the applicability of our approach we used the PLS-R models to calculate the LL of simulated sites. This simulation indicated a clear increase in LL production along the transition from Avicennia- to Rhizophora-dominated mangroves. As the leaf litter of these species differ substantially in chemical composition and decomposability, such transition in species composition will likely affect nutrient dynamics in the region. Thus, we suggest reporting species-specific site characteristics along with LL in future studies to obtain more robust models to predict future LL production at sites of changing vegetation structure.

Bacterial community response to a preindustrial-to-future CO2 gradient is limited and soil specific in Texas Prairie grassland.

Rising atmospheric CO2 concentration directly stimulates plant productivity and affects nutrient dynamics in the soil. However, the influence of CO2 enrichment on soil bacterial communities remains elusive, likely due to their complex interactions with a wide range of plant and soil properties. Here, we investigated the bacterial community response to a decade long preindustrial-to-future CO2 gradient (250-500ppm) among three contrasting soil types using 16S rRNA gene amplicon sequencing. In addition, we examined the effect of seasonal variation and plant species composition on bacterial communities. We found that Shannon index (H') and Faith's phylogenetic diversity (PD) did not change in response to the CO2 gradient (R2 =0.01, p>0.05). CO2 gradient and season also had a negligible effect on overall community structure, although silty clay soil communities were better structured on a CO2 gradient (p<0.001) among three soils. Similarly, CO2 gradient had no significant effect on the relative abundance of different phyla. However, we observed soil-specific variation of CO2 effects in a few individual families. For example, the abundance of Pirellulaceae family decreased linearly with CO2 gradient, but only in sandy loam soils. Conversely, the abundance of Micromonosporaceae and Gaillaceae families increased with CO2 gradient in clay soils. Soil water content (SWC) and nutrient properties were the key environmental constraints shaping bacterial community structure, one manifestation of which was a decline in bacterial diversity with increasing SWC. Furthermore, the impact of plant species composition on community structure was secondary to the strong influence of soil properties. Taken together, our findings indicate that bacterial communities may be largely unresponsive to indirect effects of CO2 enrichment through plants. Instead, bacterial communities are strongly regulated by edaphic conditions, presumably because soil differences create distinct environmental niches for bacteria.

Phosphorus fractions in subtropical soils depending on land use

Land-use change from forest to agriculture, which is driven by the demands of sustaining the growing global population, affects nutrient dynamics and availability in soil. Although phosphorus (P) is one of the main limiting nutrients in agricultural production, little is known about the influence of soil microorganisms on the dynamics of P cycling in subtropical land use systems. The objective was to assess the impacts of land use (organic farming, conventional farming and forest) on forms and distribution of P in soil.After conversion of forest, the P stock significantly increased by 373% and 170% in soil under organic farming at 0–10 and 10–20 cm depth, respectively. In conventional farming, the P stock increased by 64% and 36% at 0–10 cm and 10–20 cm depth, respectively compared to forest. The larger (up to 4 times) fraction of organic P (Po) than inorganic P (Pi) implies that total P is regulated by organic P. Easily-available P fractions (microbial biomass P, NaHCO3-Pi and Po), moderately available P (NaOH-Po) and non-available P (HCl-Pi and Po) were much higher in organic farming than conventional farming and forest, especially at the 0–10 cm depth. Compared to organic farming, the higher (>100) Corg: Po ratio that soils under conventional farming and forest are P limited which correspond with higher (2–8 times) activity of acid phosphatase in conventional farming and forest. Concluding, land use and management practices i.e. crop rotation, residue input and farmyard manure application significantly increase different fractions of P in organic farming.

How the deadwood of different tree species in various stages of decomposition affected nutrient dynamics?

PurposeThe aim of the study was to estimate how the deadwood of different tree species in various stages of decomposition affected nutrient dynamics.Materials and methodsThe deadwood of eight species (common alder, common aspen, common ash, silver fir, pedunculate oak, Norway spruce, common hornbeam and silver birch) was selected. Three logs from each species in the third, fourth and fifth decay classes were chosen for analysis. Wood in the third decay class was characterised by larger hard fragments, fragmented bark and no branches; in the fourth decay class, it was characterised by small pieces and a fragmented bark; and in the fifth decay class, it was characterised by a soft texture and no bark. The investigation was carried out in the Czarna Rózga Reserve in Central Poland. Tension lysimeters were installed under each log in the humus horizon. The water samples collected from tension lysimeters were chemically analysed in the laboratory. The water chemistry was analysed by means of ion chromatography using a DIONEX ICS 5000 unit.Results and discussionThe leachate obtained from different tree species contained different ion concentrations. The high similarity of the concentration of total anions and statistically significant differences in the content of total cations were determined in the leachate from the wood of coniferous and deciduous species. The concentration of the cations increases with the advancement of the decomposition level. A general linear model analysis demonstrates that wood species and the decomposition classes are of equal importance in defining the ion composition of the filtrate leaching from deadwood.ConclusionsWood at the highest decomposition stage releases more ions to the surface soil layers than wood at the lower decay class. An exception from the rule is the wood of birch, which in the III decay class releases more ions than in its higher decay classes. When comparing the ionic composition of leachate released from wood of coniferous and deciduous tree species, the latter are characterised by higher cation concentrations in comparison with coniferous species. Among the deciduous species, wood of such species as ash, hornbeam, aspen, birch and alder has the most favourable effects on the soil surface horizons through its supply with ionic substances. The ash wood releases high amounts of calcium, hornbeam wood releases magnesium and sodium, and aspen releases calcium, potassium and nitrate anion. From the analysed coniferous species, fir wood has a more favourable effect in terms of ion release to soil than spruce wood.