The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hong Xiao - One of the best experts on this subject based on the ideXlab platform.
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soil acidification reduces the effects of short term Nutrient Enrichment on plant and soil biota and their interactions in grasslands
Global Change Biology, 2020Co-Authors: Hong Xiao, Bing Wang, Dima Chen, Yuhe Zhu, Yongfei BaiAbstract:Soil nitrogen (N) and phosphorus (P) contents, and soil acidification have greatly increased in grassland ecosystems due to increased industrial and agricultural activities. As major environmental and economic concerns worldwide, Nutrient Enrichment and soil acidification can lead to substantial changes in the diversity and structure of plant and soil communities. Although the separate effects of N and P Enrichment on soil food webs have been assessed across different ecosystems, the combined effects of N and P Enrichment on multiple trophic levels in soil food webs have not been studied in semiarid grasslands experiencing soil acidification. Here we conducted a short-term N and P Enrichment experiment in non-acidified and acidified soil in a semiarid grassland on the Mongolian Plateau. We found that net primary productivity was not affected by N or P Enrichment alone in either non-acidified or acidified soil, but was increased by combined N and P Enrichment in both non-acidified and acidified soil. Nutrient Enrichment decreased the biomass of most microbial groups in non-acidified soil (the decrease tended to be greatest with combined N and P Enrichment) but not in acidified soil, and did not affect most soil nematode variables in non-acidified or acidified soil. Nutrient Enrichment also changed plant and microbial community structure in non-acidified but not in acidified soil, and had no effect on nematode community structure in non-acidified or acidified soil. These results indicate that the responses to short-term Nutrient Enrichment were weaker for higher trophic groups (nematodes) than for lower trophic groups (microorganisms) and primary producers (plants). The findings increase our understanding of the effects of Nutrient Enrichment on multiple trophic levels of soil food webs, and highlight that soil acidification, as an anthropogenic stressor, reduced the responses of plants and soil food webs to Nutrient Enrichment and weakened plant-soil interactions.
Catherine E. Lovelock - One of the best experts on this subject based on the ideXlab platform.
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the contrasting effects of Nutrient Enrichment on growth biomass allocation and decomposition of plant tissue in coastal wetlands
Plant and Soil, 2017Co-Authors: Matthew A Hayes, Amber Jesse, Basam Tabet, Ruth Reef, Joost A Keuskamp, Catherine E. LovelockAbstract:Aims Eutrophication of coastal waters can have consequences for the growth, function and soil processes of coastal wetlands. Our aims were to assess how Nutrient Enrichment affects growth, biomass allocation and decomposition of plant tissues of a common and widespread mangrove, Avicennia marina, and how eutrophication drives changes in below-ground carbon sequestration.
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the contrasting effects of Nutrient Enrichment on growth biomass allocation and decomposition of plant tissue in coastal wetlands
Plant and Soil, 2017Co-Authors: Matthew A Hayes, Amber Jesse, Basam Tabet, Ruth Reef, Joost A Keuskamp, Catherine E. LovelockAbstract:Eutrophication of coastal waters can have consequences for the growth, function and soil processes of coastal wetlands. Our aims were to assess how Nutrient Enrichment affects growth, biomass allocation and decomposition of plant tissues of a common and widespread mangrove, Avicennia marina, and how eutrophication drives changes in below-ground carbon sequestration. We assessed this through the measurement of above- and belowground growth and decomposition rates of plants and plant tissue in unenriched or Nutrient enriched treatments. Nutrient Enrichment increased biomass allocation above-ground compared to below-ground in seedlings but not in fully developed, mature trees where we observed the opposite pattern. Experiments to assess root decomposition found that 40–50% of biomass was lost within six months with little change between 12 and 18 months, indicating a high potential for accumulation of organic matter over time. We estimate root-derived carbon sequestration rates of 53, 250 and 94 g C m−2 year−1 for unenriched control, N and P enriched treatments, respectively. These results show coastal eutrophication can be beneficial and detrimental to ecosystem function of coastal plants. Eutrophication stimulates root growth in fully developed trees, increasing organic matter input to soils. Our data suggests that organic matter accumulation will increase in areas with high Nutrient availability where root growth is increased and rates of decomposition are low.
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Nutrient Enrichment increases mortality of mangroves
PLOS ONE, 2009Co-Authors: Catherine E. Lovelock, Marilyn C Ball, Katherine C Martin, Ilka C FellerAbstract:Nutrient Enrichment of the coastal zone places intense pressure on marine communities. Previous studies have shown that growth of intertidal mangrove forests is accelerated with enhanced Nutrient availability. However, Nutrient Enrichment favours growth of shoots relative to roots, thus enhancing growth rates but increasing vulnerability to environmental stresses that adversely affect plant water relations. Two such stresses are high salinity and low humidity, both of which require greater investment in roots to meet the demands for water by the shoots. Here we present data from a global network of sites that documents enhanced mortality of mangroves with experimental Nutrient Enrichment at sites where high sediment salinity was coincident with low rainfall and low humidity. Thus the benefits of increased mangrove growth in response to coastal eutrophication is offset by the costs of decreased resilience due to mortality during drought, with mortality increasing with soil water salinity along climatic gradients.
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mangrove growth in new zealand estuaries the role of Nutrient Enrichment at sites with contrasting rates of sedimentation
Oecologia, 2007Co-Authors: Catherine E. Lovelock, Ilka C Feller, Joanne I Ellis, Ann Maree Schwarz, Nicole Hancock, Pip Nichols, Brian K SorrellAbstract:Mangrove forest coverage is increasing in the estuaries of the North Island of New Zealand, causing changes in estuarine ecosystem structure and function. Sedimentation and associated Nutrient Enrichment have been proposed to be factors leading to increases in mangrove cover, but the relative importance of each of these factors is unknown. We conducted a fertilization study in estuaries with different sedimentation histories in order to determine the role of Nutrient Enrichment in stimulating mangrove growth and forest development. We expected that if mangroves were Nutrient-limited, Nutrient Enrichment would lead to increases in mangrove growth and forest structure and that Nutrient Enrichment of trees in our site with low sedimentation would give rise to trees and sediments that converged in terms of functional characteristics on control sites in our high sedimentation site. The effects of fertilizing with nitrogen (N) varied among sites and across the intertidal zone, with enhancements in growth, photosynthetic carbon gain, N resorption prior to leaf senescence and the leaf area index of canopies being significantly greater at the high sedimentation sites than at the low sedimentation sites, and in landward dwarf trees compared to seaward fringing trees. Sediment respiration (CO2 efflux) was higher at the high sedimentation site than at the low one sedimentation site, but it was not significantly affected by fertilization, suggesting that the high sedimentation site supported greater bacterial mineralization of sediment carbon. Nutrient Enrichment of the coastal zone has a role in facilitating the expansion of mangroves in estuaries of the North Island of New Zealand, but this effect is secondary to that of sedimentation, which increases habitat area and stimulates growth. In estuaries with high sediment loads, Enrichment with N will cause greater mangrove growth and further changes in ecosystem function.
Eric M. Lind - One of the best experts on this subject based on the ideXlab platform.
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Belowground Biomass Response to Nutrient Enrichment Depends on Light Limitation Across Globally Distributed Grasslands
Ecosystems, 2019Co-Authors: Elsa E. Cleland, Eric M. Lind, Nicole M. Decrappeo, Elizabeth Delorenze, Rachel Abbott Wilkins, Peter B. Adler, Jonathan D. Bakker, Cynthia S. Brown, Kendi F. Davies, Ellen EschAbstract:Anthropogenic activities are increasing Nutrient inputs to ecosystems worldwide, with consequences for global carbon and Nutrient cycles. Recent meta-analyses show that aboveground primary production is often co-limited by multiple Nutrients; however, little is known about how root production responds to changes in Nutrient availability. At twenty-nine grassland sites on four continents, we quantified shallow root biomass responses to nitrogen (N), phosphorus (P) and potassium plus microNutrient Enrichment and compared below- and aboveground responses. We hypothesized that optimal allocation theory would predict context dependence in root biomass responses to Nutrient Enrichment, given variation among sites in the resources limiting to plant growth (specifically light versus Nutrients). Consistent with the predictions of optimal allocation theory, the proportion of total biomass belowground declined with N or P addition, due to increased biomass aboveground (for N and P) and decreased biomass belowground (N, particularly in sites with low canopy light penetration). Absolute root biomass increased with N addition where light was abundant at the soil surface, but declined in sites where the grassland canopy intercepted a large proportion of incoming light. These results demonstrate that belowground responses to changes in resource supply can differ strongly from aboveground responses, which could significantly modify predictions of future rates of Nutrient cycling and carbon sequestration. Our results also highlight how optimal allocation theory developed for individual plants may help predict belowground biomass responses to Nutrient Enrichment at the ecosystem scale across wide climatic and environmental gradients.
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Sensitivity of global soil carbon stocks to combined Nutrient Enrichment
Ecology Letters, 2019Co-Authors: Thomas W. Crowther, Charlotte E. Riggs, Elizabeth T. Borer, Eric W. Seabloom, Sarah E. Hobbie, Jasper Wubs, Jennifer Firn, Eric M. Lind, Peter B. Adler, Laureano A. GherardiAbstract:Soil stores approximately twice as much carbon as the atmosphere and fluctuations in the size of the soil carbon pool directly influence climate conditions. We used the Nutrient Network global change experiment to examine how anthropogenic Nutrient Enrichment might influence grassland soil carbon storage at a global scale. In isolation, Enrichment of nitrogen and phosphorous had minimal impacts on soil carbon storage. However, when these Nutrients were added in combination with potassium and microNutrients, soil carbon stocks changed considerably, with an average increase of 0.04 KgCm−2 year−1 (standard deviation 0.18 KgCm−2 year−1). These effects did not correlate with changes in primary productivity, suggesting that soil carbon decomposition may have been restricted. Although Nutrient Enrichment caused soil carbon gains most dry, sandy regions, considerable absolute losses of soil carbon may occur in high‐latitude regions that store the majority of the world's soil carbon. These mechanistic insights into the sensitivity of grassland carbon stocks to Nutrient Enrichment can facilitate biochemical modelling efforts to project carbon cycling under future climate scenarios.
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climate modifies response of non native and native species richness to Nutrient Enrichment
Science & Engineering Faculty, 2016Co-Authors: Habacuc Floresmoreno, Eric W. Seabloom, Eric M. Lind, Peter B Reich, Lauren L Sullivan, Laura Yahdjian, Andrew S Macdougall, Lara G Reichmann, Juan Alberti, Selene BaezAbstract:Free to read Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where Nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental Nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of Nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with Nutrient addition independent of climate; however, Nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to Nutrient Enrichment. Our results suggest that the negative effect of Nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change.
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climate modifies response of non native and native species richness to Nutrient Enrichment
Philosophical Transactions of the Royal Society B, 2016Co-Authors: Habacuc Floresmoreno, Eric W. Seabloom, Eric M. Lind, Peter B Reich, Lauren L Sullivan, Laura Yahdjian, Andrew S Macdougall, Lara G Reichmann, Juan AlbertiAbstract:Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where Nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental Nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of Nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with Nutrient addition independent of climate; however, Nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to Nutrient Enrichment. Our results suggest that the negative effect of Nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change.
Christoph D Matthaei - One of the best experts on this subject based on the ideXlab platform.
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multiple stressors in agricultural streams a mesocosm study of interactions among raised water temperature sediment addition and Nutrient Enrichment
PLOS ONE, 2012Co-Authors: Jeremy J Piggott, Colin R Townsend, Katharina Lange, Christoph D MatthaeiAbstract:Changes to land use affect streams through Nutrient Enrichment, increased inputs of sediment and, where riparian vegetation has been removed, raised water temperature. We manipulated all three stressors in experimental streamside channels for 30 days and determined the individual and pair-wise combined effects on benthic invertebrate and algal communities and on leaf decay, a measure of ecosystem functioning. We added Nutrients (phosphorus+nitrogen; high, intermediate, natural) and/or sediment (grain size 0.2 mm; high, intermediate, natural) to 18 channels supplied with water from a nearby stream. Temperature was increased by 1.4°C in half the channels, simulating the loss of upstream and adjacent riparian shade. Sediment affected 93% of all biological response variables (either as an individual effect or via an interaction with another stressor) generally in a negative manner, while Nutrient Enrichment affected 59% (mostly positive) and raised temperature 59% (mostly positive). More of the algal components of the community responded to stressors acting individually than did invertebrate components, whereas pair-wise stressor interactions were more common in the invertebrate community. Stressors interacted often and in a complex manner, with interactions between sediment and temperature most common. Thus, the negative impact of high sediment on taxon richness of both algae and invertebrates was stronger at raised temperature, further reducing biodiversity. In addition, the decay rate of leaf material (strength loss) accelerated with Nutrient Enrichment at ambient but not at raised temperature. A key implication of our findings for resource managers is that the removal of riparian shading from streams already subjected to high sediment inputs, or land-use changes that increase erosion or Nutrient runoff in a landscape without riparian buffers, may have unexpected effects on stream health. We highlight the likely importance of intact or restored buffer strips, both in reducing sediment input and in maintaining cooler water temperatures.
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multiple stressors in agricultural streams interactions among sediment addition Nutrient Enrichment and water abstraction
Journal of Applied Ecology, 2010Co-Authors: Christoph D Matthaei, Jeremy J Piggott, Colin R TownsendAbstract:Summary 1. Many ecosystems are influenced simultaneously by multiple stressors, and the consequences of stressors are often unpredictable on the basis of knowledge of single effects. Agriculture affects streams world-wide via Nutrient Enrichment, elevated fine sediment and water abstraction for irrigation, but the combined impacts of these stressors are unknown. 2. We manipulated all three stressors simultaneously in an 18-day experiment and determined their individual and pair-wise combined effects on benthic invertebrates, algal biomass and leaf decay. We added Nutrients (phosphorus plus nitrogen) and/or fine sediment (grain size 0·2 mm) to 18 experimental stream channels (dimensions 250 × 15 × 15 cm) supplied with water from a nearby stream. Three sediment and three Nutrient treatments (high, intermediate, natural) were applied to each of six channels while flow was reduced by 80% in half the channels. Invertebrates (composition, abundance) and algae (chlorophyll a) were assayed using ceramic tile substrata and leaf decay was assayed using bundled leaves of a native shrub. Invertebrates colonizing leaf packs were also sampled. 3. Effects of sediment addition and flow reduction on biological response parameters were twice as common as Nutrient Enrichment effects. Nutrient Enrichment increased total invertebrate abundance on tiles, algal biomass accrual and leaf decay rates, whereas both sediment addition (at the highest level) and flow reduction had mostly negative effects (e.g. reduced algal biomass, invertebrate abundance and/or taxonomic richness). 4. Stressors interacted often, and interactions between sediment and flow were particularly common. The negative impact of added sediment on aquatic biota was stronger at reduced flow, especially on tile substrata that were more exposed to the current than leaf-pack substrata. 5. Synthesis and applications. Our key findings imply that abstracting water from a stream already subjected to high fine sediment inputs may have far worse effects on the invertebrate fauna than abstraction from a similar stream with lower sediment levels. Aquatic resource managers should be aware of this important interaction between multiple stressors.
Andrew P Negri - One of the best experts on this subject based on the ideXlab platform.
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Effects of suspended sediments and Nutrient Enrichment on juvenile corals.
Marine pollution bulletin, 2017Co-Authors: Adriana Humanes, Artur Fink, Bette L Willis, Katharina E Fabricius, Dirk De Beer, Andrew P NegriAbstract:Three to six-month-old juveniles of Acropora tenuis, A. millepora and Pocillopora acuta were experimentally co-exposed to Nutrient Enrichment and suspended sediments (without light attenuation or sediment deposition) for 40days. Suspended sediments reduced survivorship of A. millepora strongly, proportional to the sediment concentration, but not in A. tenuis or P. acuta juveniles. However, juvenile growth of the latter two species was reduced to less than half or to zero, respectively. Additionally, suspended sediments increased effective quantum yields of symbionts associated with A. millepora and A. tenuis, but not those associated with P. acuta. Nutrient Enrichment did not significantly affect juvenile survivorship, growth or photophysiology for any of the three species, either as a sole stressor or in combination with suspended sediments. Our results indicate that exposure to suspended sediments can be energetically costly for juveniles of some coral species, implying detrimental longer-term but species-specific repercussions for populations and coral cover.
