Long-term nitrogen loading alleviates phosphorus limitation in terrestrial ecosystems
Chen, Ji ; Groenigen, Kees J. van; Hungate, Bruce A. ; Terrer, César ; Groenigen, Jan Willem van; Maestre, Fernando T. ; Ying, Samantha C. ; Luo, Yiqi ; Jørgensen, Uffe ; Sinsabaugh, Robert L. ; Olesen, Jørgen E. ; Elsgaard, Lars - \ 2020
Global Change Biology 26 (2020)9. - ISSN 1354-1013 - p. 5077 - 5086.
microbial biomass - nitrogen addition - nutrient stoichiometry balance - phosphorus limitation - soil nitrogen content - soil pH - soil phosphatase activity - soil phosphorus content
Increased human-derived nitrogen (N) deposition to terrestrial ecosystems has resulted in widespread phosphorus (P) limitation of net primary productivity. However, it remains unclear if and how N-induced P limitation varies over time. Soil extracellular phosphatases catalyze the hydrolysis of P from soil organic matter, an important adaptive mechanism for ecosystems to cope with N-induced P limitation. Here we show, using a meta-analysis of 140 studies and 668 observations worldwide, that N stimulation of soil phosphatase activity diminishes over time. Whereas short-term N loading (≤5 years) significantly increased soil phosphatase activity by 28%, long-term N loading had no significant effect. Nitrogen loading did not affect soil available P and total P content in either short- or long-term studies. Together, these results suggest that N-induced P limitation in ecosystems is alleviated in the long-term through the initial stimulation of soil phosphatase activity, thereby securing P supply to support plant growth. Our results suggest that increases in terrestrial carbon uptake due to ongoing anthropogenic N loading may be greater than previously thought.
Nitrogen Deposition Maintains a Positive Effect on Terrestrial Carbon Sequestration in the 21st Century Despite Growing Phosphorus Limitation at Regional Scales
Fleischer, Katrin ; Dolman, A.J. ; Molen, Michiel K. van der; Rebel, Karin T. ; Erisman, Jan Willem ; Wassen, Martin J. ; Pak, Bernard ; Lu, Xingjie ; Rammig, Anja ; Wang, Ying Ping - \ 2019
Global Biogeochemical Cycles 33 (2019)6. - ISSN 0886-6236 - p. 810 - 824.
carbon sequestration - land carbon sink - nitrogen deposition - nitrogen fixation - phosphorus limitation - terrestrial ecosystems
Nitrogen (N) and phosphorus (P) are two dominant nutrients regulating the productivity of most terrestrial ecosystems. The growing imbalance of anthropogenic N and P inputs into the future is estimated to exacerbate P limitation on land and limit the land carbon (C) sink, so that we hypothesized that P limitation will increasingly reduce C sequestered per unit N deposited into the future. Using a global land surface model (CABLE), we simulated the effects of increased N deposition with and without P limitation on land C uptake and the fate of deposited N on land from 1901 to 2100. Contrary to our hypothesis, we found that N deposition continued to induce land C sequestration into the future, contributing to 15% of future C sequestration as opposed to 6% over the historical period. P limitation reduced the future land C uptake per unit N deposited only moderately at the global scale but P limitation increasingly caused N deposition to have net negative effects on the land C balance in the temperate zone. P limitation further increased the fraction of deposited N that is lost via leaching to aquatic ecosystems, globally from 38.5% over the historical period to 53% into the future, and up to 75% in tropical ecosystems. Our results suggest continued N demand for plant productivity but also indicate growing adverse N deposition effects in the future biosphere, not fully accounted for in global models, emphasizing the urgent need to elaborate on model representations of N and P dynamics.
Food quality dominates the impact of food quantity on Daphnia life history: possible implications for re-oligotrophication
Sarpe, D. ; Senerpont Domis, L.N. de; Declerck, S.A.J. ; Donk, E. van; Ibelings, B.W. - \ 2014
Inland Waters : Journal of the International Society of Limnology 4 (2014)4. - ISSN 2044-2041 - p. 363 - 368.
phosphorus limitation - nutrient limitation - long-term - lakes - carbon - eutrophication - growth
The elemental composition of phytoplankton is highly variable compared to the relatively narrow stoichiometry of zooplankton grazers. Using a full factorial design, we tested the effects of alterations in algal elemental composition (i.e., food quality) combined with food quantity on the life history of a Daphnia galeata clone from Lake IJsselmeer. Lower food quality reduced survival, growth, and reproduction. Food quantity became important at high food quality only. The strong effect of food quality indicates the potential for a stoichiometric bottleneck in Lake IJsselmeer, resulting in less high quality food for higher trophic levels as a result of re-oligotrophication.
Iron oxidation kinetics and phosphate immobilization along the flow-path from groundwater into surface water
Grift, B. van der; Rozemeijer, J.C. ; Griffioen, J. ; Velde, Y. van der - \ 2014
Hydrology and Earth System Sciences 18 (2014)11. - ISSN 1027-5606 - p. 4687 - 4702.
suspended sediment - ferrous iron - fresh-water - phosphorus limitation - nutrient dynamics - fe(ii) oxidation - arsenic removal - natural-waters - riparian zone - river
The retention of phosphorus in surface waters through co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from groundwater into surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and surface water, we investigated Fe(II) oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II) by O-2. Seasonal changes in climatic conditions affected the Fe(II) oxidation process. Lower pH and lower temperatures in winter (compared to summer) resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than a week before complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilization of dissolved P during the initial stage of the Fe(II) oxidation process which results in P-depleted water before Fe(II) is completely depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox gradients seems an important geochemical mechanism in the transformation of dissolved phosphate to structural phosphate and, therefore, a major control on the P retention in natural waters that drain anaerobic aquifers.
Key role of symbiotic dinitrogen fixation in tropical forest secondary succession
Batterman, S.A. ; Hedin, L.O. ; Breugel, M. van; Ransijn, J. ; Craven, D.J. ; Hall, J.S. - \ 2013
Nature 502 (2013). - ISSN 0028-0836 - p. 224 - 227.
nitrogen-fixation - phosphorus limitation - biomass - dynamics - growth - amazonia - soils - land
Forests contribute a significant portion of the land carbon sink, but their ability to sequester CO2 may be constrained by nitrogen1, 2, 3, 4, 5, 6, a major plant-limiting nutrient. Many tropical forests possess tree species capable of fixing atmospheric dinitrogen (N2)7, but it is unclear whether this functional group can supply the nitrogen needed as forests recover from disturbance or previous land use1, or expand in response to rising CO2 (refs 6, 8). Here we identify a powerful feedback mechanism in which N2 fixation can overcome ecosystem-scale deficiencies in nitrogen that emerge during periods of rapid biomass accumulation in tropical forests. Over a 300-year chronosequence in Panama, N2-fixing tree species accumulated carbon up to nine times faster per individual than their non-fixing neighbours (greatest difference in youngest forests), and showed species-specific differences in the amount and timing of fixation. As a result of fast growth and high fixation, fixers provided a large fraction of the nitrogen needed to support net forest growth (50,000¿kg carbon per hectare) in the first 12¿years. A key element of ecosystem functional diversity was ensured by the presence of different N2-fixing tree species across the entire forest age sequence. These findings show that symbiotic N2 fixation can have a central role in nitrogen cycling during tropical forest stand development, with potentially important implications for the ability of tropical forests to sequester CO2.
How nitrogen and sulphur addition, and a single drought event affect root phosphatase activity in Phalaris arundinacea
Robroek, B.J.M. ; Adema, E.B. ; Venterink, H.O. ; Leonardson, L. ; Wassen, M.J. - \ 2009
Science of the Total Environment 407 (2009)7. - ISSN 0048-9697 - p. 2342 - 2348.
fresh-water wetlands - species richness - phosphorus limitation - eutrophication - deposition - biomass - fertilization - grasslands - growth - carbon
Conservation and restoration of fens and fen meadows often aim to reduce soil nutrients, mainly nitrogen (N) andphosphorus (P). The biogeochemistry of P has received much attention as P-enrichment is expected to negatively impact on species diversity in wetlands. It is known that N, sulphur (S) and hydrological conditions affect the biogeochemistry of P, yet their interactive effects on P-dynamics are largely unknown. Additionally, in Europe, climate change has been predicted to lead to increases in summer drought. We performed a greenhouse experiment to elucidate the interactive effects of N, S and a single drought event on the P-availability for Phalaris arundinacea. Additionally, the response of plant phosphatase activity to these factors was measured over the two year experimental period. In contrast to results from earlier experiments, our treatments hardly affected soil P-availability. This may be explained by the higher pH in our soils, hampering the formation of Fe-P or Fe-Al complexes. Addition of S, however, decreased the plants N:P ratio, indicating an effect of S on the N:P stoichiometry and an effect on the plant's P-demand. Phosphatase activity increased significantly after addition of S, but was not affected by the addition of N or a single drought event. Root phosphatase activity was also positively related to plant tissue N and P concentrations, plant N and P uptake, and plant aboveground biomass, suggesting that the phosphatase enzyme influences P-biogeochemistry. Our results demonstrated that it is difficult to predict the effects of wetland restoration, since the involved mechanisms are not fully understood. Short-term and long-term effects on root phosphatase activity may differ considerably. Additionally, the addition of S can lead to unexpected effects on the biogeochemistry of P. Our results showed that natural resource managers should be careful when restoring degraded fens or preventing desiccation of fen ecosystems.
The origin and development of a minerotrophic soak on an Irish raised bog: An interpretation of depth profiles of hydrochemistry and peat chemistry
Crushell, P.H. ; Smolders, A.J.P. ; Schouten, M.G.C. ; Roelofs, J.G.M. ; Wirdum, G. van - \ 2009
Holocene 19 (2009)6. - ISSN 0959-6836 - p. 921 - 935.
phosphorus limitation - carbon isotopes - organic-matter - nitrogen - sphagnum - peatlands - groundwater - delta-n-15 - plants - restoration
The peat and pore-water biogeochemistry of an Irish oceanic raised bog are reported with a view to understanding the origin and development of a minerotrophic soak contained within an ombrotrophic bog. Depth profiles of electrical conductivity, pore-water chemistry and peat chemistry were recorded from the mire surface down to a maximum depth of 10 m (approximately 1 m into the underlying mineral soil) from the centre of Lough Roe, a minerotrophic soak on Clara Bog in the Irish midlands, and from a location in the surrounding bog. Distinct differences in the hydrochemistry and peat chemistry between both sites are evident in the upper 5 m of the profile, indicating that conditions differed during the latter development of the mire, despite both sites being located on the apex of the raised bog dome. As expected, the profiles recorded from the ombrotrophic bog are characterised by low ionic concentrations in the upper bog peat with an increase in the concentration of calcium and other ions in the lower fen peat (from 5.5 m depth). At the Lough Roe site, the profile shows relatively high concentrations of calcium and other ions in the upper part of the profile. To our knowledge, this is the first report of such detailed minerotrophic chemical profiles from the central area of a raised bog dome. We hypothesize that the relevant minerals originate from the underlying clay layer and fen peat within the basin of the bog and the minerals prevailed within the soak because of (1) the generation of a flow of water from the developing bog through the minerotrophic fen peat towards the soak during its early development, and (2) increased rates of decomposition within the soak throughout its existence. The implications for the future conservation management of the site are discussed
Vegetation succession as affected by decreasing nitrogen deposition, soil characteristics and site management: A modelling approach
Wamelink, G.W.W. ; Dobben, H.F. van; Berendse, F. - \ 2009
Forest Ecology and Management 258 (2009)8. - ISSN 0378-1127 - p. 1762 - 1773.
organic-matter - seminatural vegetation - phosphorus limitation - botanical composition - heathland ecosystems - plant-populations - salt-marsh - forest - dynamics - competition
After many years of increasing nitrogen deposition, the deposition rates are now decreasing. A major question is whether this will result in the expected positive effects on plant species diversity. Long-term experiments that investigate the effects of decreasing deposition are not available. Model simulations may yield insight into the possible effects of decreasing nitrogen deposition on the vegetation. Therefore we developed the vegetation succession model SUMO which is closely linked to the soil model SMART2. In SUMO, the biomass development of five functional plant types is simulated as a function of nitrogen availability, light interception and management. The model simulates the change in biomass distribution over functional types during the succession from almost bare soil via grassland or heathland to various forest types. The model was validated on three sites in The Netherlands and one site in the UK. The aboveground biomass of two grassland vegetation types was well simulated, as well as the aboveground biomass of heathlands during succession of sod removal. Some of the stages of forest succession were simulated less well, but the calculated biomass in the older stages agreed with measured values. To explore the long-term effect of a decrease in nitrogen deposition, we applied the model to a heathland and a pine stand. In the heathland a major change was predicted as a result of decreasing nitrogen deposition in combination with turf stripping. The dominance of grasses changed into a dominance of dwarf shrubs, whereas at continuing high levels of nitrogen deposition grasses remained dominant. In contrast, the simulations indicated only very small effects of a decreasing N deposition in pine forests. This difference is due to the removal of excess nitrogen by management (turf stripping) in the heathland, whereas the more extensive management in the forest hardly removes any nitrogen from the system. The main conclusion from these examples is that a decrease of nitrogen deposition may retard succession, and consequently increase biodiversity in heathland but probably not in forest. The effects of declining N deposition depend on the amount of N that is removed from the system as a consequence of the various management regimes. (C) 2009 Elsevier B.V. All rights reserved.