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Gaius R. Shaver - One of the best experts on this subject based on the ideXlab platform.
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Nitrate is an important nitrogen source for Arctic Tundra plants.
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Xue-yan Liu, Gaius R. Shaver, Anne E Giblin, Keisuke Koba, Lina Koyama, Sarah E. Hobbie, Marissa S. Weiss, Yoshiyuki Inagaki, Satoru Hobara, Knute J NadelhofferAbstract:Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO3-) is a major N form used by plants worldwide, it is discounted as a N source for Arctic Tundra plants because of extremely low NO3- concentrations in Arctic Tundra soils, undetectable soil nitrification, and plant-tissue NO3- that is typically below detection limits. Here we reexamine NO3- use by Tundra plants using a sensitive denitrifier method to analyze plant-tissue NO3- Soil-derived NO3- was detected in Tundra plant tissues, and Tundra plants took up soil NO3- at comparable rates to plants from relatively NO3--rich ecosystems in other biomes. Nitrate assimilation determined by 15N enrichments of leaf NO3- relative to soil NO3- accounted for 4 to 52% (as estimated by a Bayesian isotope-mixing model) of species-specific total leaf N of Alaskan Tundra plants. Our finding that in situ soil NO3- availability for Tundra plants is high has important implications for Arctic ecosystems, not only in determining species compositions, but also in determining the loss of N from soils via leaching and denitrification. Plant N uptake and soil N losses can strongly influence C uptake and accumulation in Tundra soils. Accordingly, this evidence of NO3- availability in Tundra soils is crucial for predicting C storage in Tundra.
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Carbon loss from an unprecedented Arctic Tundra wildfire
Nature, 2011Co-Authors: Michelle C. Mack, M. Syndonia Bret-harte, Teresa N. Hollingsworth, Randi R. Jandt, Edward A. G. Schuur, Gaius R. Shaver, David L. VerbylaAbstract:In 2007, an area of more than 1,000 square kilometres of Alaskan Tundra was destroyed by a single fire, more than doubling the cumulative area burnt in this region since 1950. Michelle Mack and colleagues now show that, in the process, 2.1 teragrams of carbon was released and about one-third of soil organic matter burned away, thereby potentially exposing permafrost soils to thaw. The amount of carbon released from the entire burn was comparable to the annual net carbon sink of the entire Arctic Tundra biome during the past 25 years of the twentieth century. As Tundra fires are expected to increase as the climate warms, combustion of 'old growth' Tundra soil could constitute a positive climate feedback, by transferring surface soil carbon to the atmosphere and accelerating the thaw and decomposition of deeper permafrost carbon. Arctic Tundra soils store large amounts of carbon (C) in organic soil layers hundreds to thousands of years old that insulate, and in some cases maintain, permafrost soils1,2. Fire has been largely absent from most of this biome since the early Holocene epoch3, but its frequency and extent are increasing, probably in response to climate warming4. The effect of fires on the C balance of Tundra landscapes, however, remains largely unknown. The Anaktuvuk River fire in 2007 burned 1,039 square kilometres of Alaska’s Arctic slope, making it the largest fire on record for the Tundra biome and doubling the cumulative area burned since 1950 (ref. 5). Here we report that Tundra ecosystems lost 2,016 ± 435 g C m−2 in the fire, an amount two orders of magnitude larger than annual net C exchange in undisturbed Tundra6. Sixty per cent of this C loss was from soil organic matter, and radiocarbon dating of residual soil layers revealed that the maximum age of soil C lost was 50 years. Scaled to the entire burned area, the fire released approximately 2.1 teragrams of C to the atmosphere, an amount similar in magnitude to the annual net C sink for the entire Arctic Tundra biome averaged over the last quarter of the twentieth century7. The magnitude of ecosystem C lost by fire, relative to both ecosystem and biome-scale fluxes, demonstrates that a climate-driven increase in Tundra fire disturbance may represent a positive feedback, potentially offsetting Arctic greening8 and influencing the net C balance of the Tundra biome.
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Inter-annual variability of NDVI in response to long-term warming and fertilization in wet sedge and tussock Tundra
Oecologia, 2005Co-Authors: Natalie T. Boelman, Marc Stieglitz, Kevin L. Griffin, Gaius R. ShaverAbstract:This study explores the relationship between the normalized difference vegetation index (NDVI) and aboveground plant biomass for tussock Tundra vegetation and compares it to a previously established NDVI–biomass relationship for wet sedge Tundra vegetation. In addition, we explore inter-annual variation in NDVI in both these contrasting vegetation communities. All measurements were taken across long-term experimental treatments in wet sedge and tussock Tundra communities at the Toolik Lake Long Term Ecological Research (LTER) site, in northern Alaska. Over 15 years (for wet sedge Tundra) and 14 years (for tussock Tundra), N and P were applied in factorial experiments (N, P and N+P), air temperature was increased using greenhouses with and without N+P fertilizer, and light intensity was reduced by 50% using shade cloth. during the peak growing seasons of 2001, 2002, and 2003, NDVI measurements were made in both the wet sedge and tussock Tundra experimental treatment plots, creating a 3-year time series of inter-annual variation in NDVI. We found that: (1) across all tussock experimental Tundra treatments, NDVI is correlated with aboveground plant biomass (r2=0.59); (2) NDVI–biomass relationships for tussock and wet sedge Tundra communities are community specific, and; (3) NDVI values for tussock Tundra communities are typically, but not always, greater than for wet sedge Tundra communities across all experimental treatments. We suggest that differences between the response of wet sedge and tussock Tundra communities in the same experimental treatments result from the contrasting degree of heterogeneity in species and functional types that characterize each of these Arctic Tundra vegetation communities.
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15N natural abundances and N use by Tundra plants.
Oecologia, 1996Co-Authors: Knute J Nadelhoffer, Gaius R. Shaver, Loretta C Johnson, Anne E Giblin, Brian Fry, Robert B. MckaneAbstract:Plant species collected from Tundra ecosystems located along a north-south transect from central Alaska to the north coast of Alaska showed large and consistent differences in 15N natural abundances. Foliar δ15N values varied by about 10% among species within each of two moist tussock Tundra sites. Differences in 15N contents among species or plant groups were consistent across moist tussock Tundra at several other sites and across five other Tundra types at a single site. Ericaceous species had the lowest δ15N values, ranging between about −8 to −6‰. Foliar 15N contents increased progressively in birch, willows and sedges to maximum δ15N values of about +2‰ in sedges. Soil 15N contents in Tundra ecosystems at our two most intensively studied sites increased with depth and δ15N values were usually higher for soils than for plants. Isotopic fractionations during soil N transformations and possibly during plant N uptake could lead to observed differences in 15N contents among plant species and between plants and soils. Patterns of variation in 15N content among species indicate that Tundra plants acquire nitrogen in extremely nutrient-poor environments by competitive partitioning of the overall N pool. Differences in plant N sources, rooting depth, mycorrhizal associations, forms of N taken up, and other factors controlling plant N uptake are possible causes of variations in δ15N values of Tundra plant species.
Knute J Nadelhoffer - One of the best experts on this subject based on the ideXlab platform.
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Nitrate is an important nitrogen source for Arctic Tundra plants.
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Xue-yan Liu, Gaius R. Shaver, Anne E Giblin, Keisuke Koba, Lina Koyama, Sarah E. Hobbie, Marissa S. Weiss, Yoshiyuki Inagaki, Satoru Hobara, Knute J NadelhofferAbstract:Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO3-) is a major N form used by plants worldwide, it is discounted as a N source for Arctic Tundra plants because of extremely low NO3- concentrations in Arctic Tundra soils, undetectable soil nitrification, and plant-tissue NO3- that is typically below detection limits. Here we reexamine NO3- use by Tundra plants using a sensitive denitrifier method to analyze plant-tissue NO3- Soil-derived NO3- was detected in Tundra plant tissues, and Tundra plants took up soil NO3- at comparable rates to plants from relatively NO3--rich ecosystems in other biomes. Nitrate assimilation determined by 15N enrichments of leaf NO3- relative to soil NO3- accounted for 4 to 52% (as estimated by a Bayesian isotope-mixing model) of species-specific total leaf N of Alaskan Tundra plants. Our finding that in situ soil NO3- availability for Tundra plants is high has important implications for Arctic ecosystems, not only in determining species compositions, but also in determining the loss of N from soils via leaching and denitrification. Plant N uptake and soil N losses can strongly influence C uptake and accumulation in Tundra soils. Accordingly, this evidence of NO3- availability in Tundra soils is crucial for predicting C storage in Tundra.
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pulse labeling studies of carbon cycling in arctic Tundra ecosystems contribution of photosynthates to soil organic matter
Global Biogeochemical Cycles, 2002Co-Authors: Loretta C Johnson, Wendy M Loya, George W Kling, Jennifer Y King, William S Reeburgh, Knute J NadelhofferAbstract:[1] To increase our understanding of carbon (C) cycling and storage in soils, we used 14C to trace C from roots into four soil organic matter (SOM) fractions and the movement of soil microbes in arctic wet sedge and tussock Tundra. For both Tundra types, the proportion of 14C activity in the soil was 6% of the total 14C-CO2 taken up by plants at each of the four harvests conducted 1, 7, 21, and 68 days after labeling. In tussock Tundra, we observed rapid microbial transformation of labile C from root exudates into more stable SOM. In wet sedge Tundra, there appears to be delayed or indirect microbial use of root exudates. The net amount of 14C label transferred to SOM by the end of the season in both Tundra types was approximately equal to the amount transferred to soils 1 day after labeling, suggesting that transfer of 14C tracer from roots to soils continued through the growing season. Overall, C inputs from living roots contributes 24 g C m−2 yr−1 in tussock Tundra and 8.8 g C m−2 yr−1 in wet sedge Tundra. These results suggest rapid belowground allocation of C by plants and subsequent incorporation of much of this C into storage in the SOM.
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biomass and co2 flux in wet sedge Tundras responses to nutrients temperature and light
Ecological Monographs, 1998Co-Authors: Gus Shaver, Loretta C Johnson, Deb H Cades, G Murray, James A Laundre, Edward B Rastetter, Knute J Nadelhoffer, Anne E GiblinAbstract:The aim of this research was to analyze the effects of increased N or P availability, increased air temperature, and decreased light intensity on wet sedge Tundra in northern Alaska. Nutrient availability was increased for 6–9 growing seasons, using N and P fertilizers in factorial experiments at three separate field sites. Air temperature was increased for six growing seasons, using plastic greenhouses at two sites, both with and without N + P fertilizer. Light intensity (photosynthetically active photon flux) was reduced by 50% for six growing seasons at the same two sites, using optically neutral shade cloth. Responses of wet sedge Tundra to these treatments were documented as changes in vegetation biomass, N mass, and P mass, changes in whole-system CO2 fluxes, and changes in species composition and leaf-level photosynthesis. Biomass, N mass, and P mass accumulation were all strongly P limited, and biomass and N mass accumulation also responded significantly to N addition with a small N × P interaction. Greenhouse warming alone had no significant effect on biomass, N mass, or P mass, although there was a consistent trend toward increased mass in the greenhouse treatments. There was a significant negative interaction between the greenhouse treatment and the N + P fertilizer treatment, i.e., the effect of the two treatments combined was to reduce biomass and N mass significantly below that of the fertilizer treatment only. Six years of shading had no significant effect on biomass, N mass, or P mass. Ecosystem CO2 fluxes included net ecosystem production (NEP; net CO2 flux), ecosystem respiration (RE, including both plant and soil respiration), and gross ecosystem production (GEP; gross ecosystem photosynthesis). All three fluxes responded to the fertilizer treatments in a pattern similar to the responses of biomass, N mass, and P mass, i.e., with a strong P response and a small, but significant, N response and N × P interaction. The greenhouse treatment also increased all three fluxes, but the greenhouse plus N + P treatment caused a significant decrease in NEP because RE increased more than GEP in this treatment. The shade treatment increased both GEP and RE, but had no effect on NEP. Most of the changes in CO2 fluxes per unit area of ground were due to changes in plant biomass, although there were additional, smaller treatment effects on CO2 fluxes per unit biomass, per unit N mass, and per unit P mass. The vegetation was composed mainly of rhizomatous sedges and rushes, but changes in species composition may have contributed to the changes in vegetation nutrient content and ecosystem-level CO2 fluxes. Carex cordorrhiza, the species with the highest nutrient concentrations in its tissues in control plots, was also the species with the greatest increase in abundance in the fertilized plots. In comparison with Eriophorum angustifolium, another species that was abundant in control plots, C. cordorrhiza had higher photosynthetic rates per unit leaf mass. Leaf photosynthesis and respiration of C. cordorrhiza also increased with fertilizer treatment, whereas they decreased or remained constant in E. angustifolium. The responses of these wet sedge Tundras were similar to those of a nearby moist tussock Tundra site that received an identical series of experiments. The main difference was the dominant P limitation in wet sedge Tundra vs. N limitation in moist tussock Tundra. Both Tundras were relatively unresponsive to the increased air temperatures in the greenhouses but showed a strong negative interaction between the greenhouse and fertilizer treatments. New data from this study suggest that the negative interaction may be driven by a large increase in respiration in warmed fertilized plots, perhaps in relation to large increases in P concentration.
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15N natural abundances and N use by Tundra plants.
Oecologia, 1996Co-Authors: Knute J Nadelhoffer, Gaius R. Shaver, Loretta C Johnson, Anne E Giblin, Brian Fry, Robert B. MckaneAbstract:Plant species collected from Tundra ecosystems located along a north-south transect from central Alaska to the north coast of Alaska showed large and consistent differences in 15N natural abundances. Foliar δ15N values varied by about 10% among species within each of two moist tussock Tundra sites. Differences in 15N contents among species or plant groups were consistent across moist tussock Tundra at several other sites and across five other Tundra types at a single site. Ericaceous species had the lowest δ15N values, ranging between about −8 to −6‰. Foliar 15N contents increased progressively in birch, willows and sedges to maximum δ15N values of about +2‰ in sedges. Soil 15N contents in Tundra ecosystems at our two most intensively studied sites increased with depth and δ15N values were usually higher for soils than for plants. Isotopic fractionations during soil N transformations and possibly during plant N uptake could lead to observed differences in 15N contents among plant species and between plants and soils. Patterns of variation in 15N content among species indicate that Tundra plants acquire nitrogen in extremely nutrient-poor environments by competitive partitioning of the overall N pool. Differences in plant N sources, rooting depth, mycorrhizal associations, forms of N taken up, and other factors controlling plant N uptake are possible causes of variations in δ15N values of Tundra plant species.
Hyojung Kwon - One of the best experts on this subject based on the ideXlab platform.
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effects of climate variability on carbon sequestration among adjacent wet sedge Tundra and moist tussock Tundra ecosystems
Journal of Geophysical Research, 2006Co-Authors: Hyojung Kwon, Walter C Oechel, Rommel C Zulueta, Steven J HastingsAbstract:[1] Temporal and spatial variability in the Arctic introduces considerable uncertainty in the estimation of the current carbon budget and Arctic ecosystem response to climate change. Few representative measurements are available for land-surface parameterization of the Arctic Tundra in regional and global climate models. In this study, the eddy covariance technique was used to measure net ecosystem CO2 exchange (NEE) of Alaskan wet sedge Tundra and moist tussock Tundra ecosystems during the summer (i.e., 1 June to 31 August) from 1999 to 2003 in order to quantify the seasonal and spatial variability in NEE and to determine controlling factors on NEE in these Tundra ecosystems. Warmer and drier conditions prevailed for the moist tussock Tundra compared with that of the wet sedge Tundra. Over the 5-year period, the wet sedge Tundra was a sink for carbon of 46.4 to 70.0 gC m−2 season−1, while the moist tussock Tundra either lost carbon of up to 60.8 gC m−2 season−1 or was in balance. The contrasting patterns of carbon balance at the two sites demonstrate that ecosystem difference can be more important in determining landscape NEE than intraseasonal and interseasonal variability due to environmental factors with respect to NEE. The wet sedge Tundra showed an acclimation (e.g., over days) to temperature, while the moist tussock Tundra illustrated a strong temperature dependence. Warming and drying accentuated ecosystem respiration in the moist tussock Tundra, causing a net loss of carbon. Better characterization of spatial variability in NEE and associated environmental controls is required to improve current and future estimates of the Arctic terrestrial carbon balance.
Anne E Giblin - One of the best experts on this subject based on the ideXlab platform.
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Nitrate is an important nitrogen source for Arctic Tundra plants.
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Xue-yan Liu, Gaius R. Shaver, Anne E Giblin, Keisuke Koba, Lina Koyama, Sarah E. Hobbie, Marissa S. Weiss, Yoshiyuki Inagaki, Satoru Hobara, Knute J NadelhofferAbstract:Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO3-) is a major N form used by plants worldwide, it is discounted as a N source for Arctic Tundra plants because of extremely low NO3- concentrations in Arctic Tundra soils, undetectable soil nitrification, and plant-tissue NO3- that is typically below detection limits. Here we reexamine NO3- use by Tundra plants using a sensitive denitrifier method to analyze plant-tissue NO3- Soil-derived NO3- was detected in Tundra plant tissues, and Tundra plants took up soil NO3- at comparable rates to plants from relatively NO3--rich ecosystems in other biomes. Nitrate assimilation determined by 15N enrichments of leaf NO3- relative to soil NO3- accounted for 4 to 52% (as estimated by a Bayesian isotope-mixing model) of species-specific total leaf N of Alaskan Tundra plants. Our finding that in situ soil NO3- availability for Tundra plants is high has important implications for Arctic ecosystems, not only in determining species compositions, but also in determining the loss of N from soils via leaching and denitrification. Plant N uptake and soil N losses can strongly influence C uptake and accumulation in Tundra soils. Accordingly, this evidence of NO3- availability in Tundra soils is crucial for predicting C storage in Tundra.
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biomass and co2 flux in wet sedge Tundras responses to nutrients temperature and light
Ecological Monographs, 1998Co-Authors: Gus Shaver, Loretta C Johnson, Deb H Cades, G Murray, James A Laundre, Edward B Rastetter, Knute J Nadelhoffer, Anne E GiblinAbstract:The aim of this research was to analyze the effects of increased N or P availability, increased air temperature, and decreased light intensity on wet sedge Tundra in northern Alaska. Nutrient availability was increased for 6–9 growing seasons, using N and P fertilizers in factorial experiments at three separate field sites. Air temperature was increased for six growing seasons, using plastic greenhouses at two sites, both with and without N + P fertilizer. Light intensity (photosynthetically active photon flux) was reduced by 50% for six growing seasons at the same two sites, using optically neutral shade cloth. Responses of wet sedge Tundra to these treatments were documented as changes in vegetation biomass, N mass, and P mass, changes in whole-system CO2 fluxes, and changes in species composition and leaf-level photosynthesis. Biomass, N mass, and P mass accumulation were all strongly P limited, and biomass and N mass accumulation also responded significantly to N addition with a small N × P interaction. Greenhouse warming alone had no significant effect on biomass, N mass, or P mass, although there was a consistent trend toward increased mass in the greenhouse treatments. There was a significant negative interaction between the greenhouse treatment and the N + P fertilizer treatment, i.e., the effect of the two treatments combined was to reduce biomass and N mass significantly below that of the fertilizer treatment only. Six years of shading had no significant effect on biomass, N mass, or P mass. Ecosystem CO2 fluxes included net ecosystem production (NEP; net CO2 flux), ecosystem respiration (RE, including both plant and soil respiration), and gross ecosystem production (GEP; gross ecosystem photosynthesis). All three fluxes responded to the fertilizer treatments in a pattern similar to the responses of biomass, N mass, and P mass, i.e., with a strong P response and a small, but significant, N response and N × P interaction. The greenhouse treatment also increased all three fluxes, but the greenhouse plus N + P treatment caused a significant decrease in NEP because RE increased more than GEP in this treatment. The shade treatment increased both GEP and RE, but had no effect on NEP. Most of the changes in CO2 fluxes per unit area of ground were due to changes in plant biomass, although there were additional, smaller treatment effects on CO2 fluxes per unit biomass, per unit N mass, and per unit P mass. The vegetation was composed mainly of rhizomatous sedges and rushes, but changes in species composition may have contributed to the changes in vegetation nutrient content and ecosystem-level CO2 fluxes. Carex cordorrhiza, the species with the highest nutrient concentrations in its tissues in control plots, was also the species with the greatest increase in abundance in the fertilized plots. In comparison with Eriophorum angustifolium, another species that was abundant in control plots, C. cordorrhiza had higher photosynthetic rates per unit leaf mass. Leaf photosynthesis and respiration of C. cordorrhiza also increased with fertilizer treatment, whereas they decreased or remained constant in E. angustifolium. The responses of these wet sedge Tundras were similar to those of a nearby moist tussock Tundra site that received an identical series of experiments. The main difference was the dominant P limitation in wet sedge Tundra vs. N limitation in moist tussock Tundra. Both Tundras were relatively unresponsive to the increased air temperatures in the greenhouses but showed a strong negative interaction between the greenhouse and fertilizer treatments. New data from this study suggest that the negative interaction may be driven by a large increase in respiration in warmed fertilized plots, perhaps in relation to large increases in P concentration.
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15N natural abundances and N use by Tundra plants.
Oecologia, 1996Co-Authors: Knute J Nadelhoffer, Gaius R. Shaver, Loretta C Johnson, Anne E Giblin, Brian Fry, Robert B. MckaneAbstract:Plant species collected from Tundra ecosystems located along a north-south transect from central Alaska to the north coast of Alaska showed large and consistent differences in 15N natural abundances. Foliar δ15N values varied by about 10% among species within each of two moist tussock Tundra sites. Differences in 15N contents among species or plant groups were consistent across moist tussock Tundra at several other sites and across five other Tundra types at a single site. Ericaceous species had the lowest δ15N values, ranging between about −8 to −6‰. Foliar 15N contents increased progressively in birch, willows and sedges to maximum δ15N values of about +2‰ in sedges. Soil 15N contents in Tundra ecosystems at our two most intensively studied sites increased with depth and δ15N values were usually higher for soils than for plants. Isotopic fractionations during soil N transformations and possibly during plant N uptake could lead to observed differences in 15N contents among plant species and between plants and soils. Patterns of variation in 15N content among species indicate that Tundra plants acquire nitrogen in extremely nutrient-poor environments by competitive partitioning of the overall N pool. Differences in plant N sources, rooting depth, mycorrhizal associations, forms of N taken up, and other factors controlling plant N uptake are possible causes of variations in δ15N values of Tundra plant species.
Joanna C Carey - One of the best experts on this subject based on the ideXlab platform.
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biogenic silica accumulation varies across tussock Tundra plant functional type
Functional Ecology, 2017Co-Authors: Joanna C Carey, Thomas C Parker, Ned Fetcher, Jianwu TangAbstract:Summary 1.Silica (SiO2) accumulation by terrestrial vegetation is an important component of the biological silica cycle because it improves overall plant fitness and influences export rates of silica from terrestrial to marine systems. However, most research on silica in plants has focused on agricultural and forested ecosystems, and knowledge of terrestrial silica cycling in the Arctic, as well as the potential impacts of climate change on the silica cycle is severely lacking. 2.We quantified biogenic silica (BSi) accumulation in above and belowground portions of three moist acidic Tundra (MAT) sites spanning a 300 km latitudinal gradient in central and northern Alaska, USA. We also examined plant silica accumulation across three main Tundra types found in the Arctic (MAT, moist non-acidic Tundra (MNT), and wet sedge Tundra (WST)). 3.BSi concentrations in live Eriophorum vaginatum, a tussock-forming sedge that is the foundation species of tussock Tundra, were not significantly (p<0.05) different across the three main sites. Concentrations of BSi in live aboveground tissue were highest in the graminoid species (0.55 ± 0.07% BSi in sedges from WST, and 0.27 ± 0.01% in E. vaginatum across the three MAT sites). Both inter-tussock Tundra species and shrubs contained substantially lower BSi concentrations than E. vaginatum. 4.Our results have implications for how shifts in vegetation cover associated with climatic warming may alter silica storage in tussock Tundra vegetation. Our calculations suggest that shrub expansion via warming will increase BSi storage in Arctic land plants due to the higher biomass associated with shrub Tundra, whereas conversion of tussock Tundra to WST via permafrost thaw would produce the opposite effect in the terrestrial plant BSi pool. Such changes in the size of the terrestrial vegetation silica reservoir could have direct consequences for the rates and timing of silica delivery to receiving waters in the Arctic. This article is protected by copyright. All rights reserved.
