The Experts below are selected from a list of 17049 Experts worldwide ranked by ideXlab platform
Ben Bondlamberty - One of the best experts on this subject based on the ideXlab platform.
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disturbance complexity and succession of Net Ecosystem Production in north america s temperate deciduous forests
Ecosphere, 2016Co-Authors: Christopher M Gough, Brady S Hardiman, Cynthia M Scheuermann, Peter S. Curtis, Ben BondlambertyAbstract:Century-old forests in the U.S. upper Midwest and Northeast power much of North America's terrestrial carbon (C) sink, but these forests' Production and C sequestration capacity are expected to soon decline as fast-growing early successional species die and are replaced by slower growing late successional species. But will this really happen? Here we marshal empirical data and ecological theory to argue that substantial declines in Net Ecosystem Production (NEP) owing to reduced forest growth, or Net primary Production (NPP), are not imminent in regrown temperate deciduous forests over the next several decades. Forest age and Production data for temperate deciduous forests, synthesized from published literature, suggest slight declines in NEP and increasing or stable NPP during middle successional stages. We revisit long-held hypotheses by EP Odum and others that suggest low-severity, high-frequency disturbances occurring in the region's aging forests will, against intuition, maintain NEP at higher-than-expected rates by increasing Ecosystem complexity, sustaining or enhancing NPP to a level that largely offsets rising C losses as heterotrophic respiration increases. This theoretical model is also supported by biological evidence and observations from the Forest Accelerated Succession Experiment in Michigan, USA. Ecosystems that experience high-severity disturbances that simplify Ecosystem complexity can exhibit substantial declines in Production during middle stages of succession. However, observations from these Ecosystems have exerted a disproportionate influence on assumptions regarding the trajectory and magnitude of age-related declines in forest Production. We conclude that there is a wide ecological space for forests to maintain NPP and, in doing so, lessens the declines in NEP, with significant implications for the future of the North American carbon sink. Our intellectual frameworks for understanding forest C cycle dynamics and resilience need to catch up to our more complex and nuanced understanding of ecological succession.
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Net primary Production and Net Ecosystem Production of a boreal black spruce wildfire chronosequence
Global Change Biology, 2004Co-Authors: Ben Bondlamberty, Chuankuan Wang, Stith T GowerAbstract:Net primary Production (NPP) was measured in seven black spruce (Picea mariana (Mill.) BSP)-dominated sites comprising a boreal forest chronosequence near Thompson, Man., Canada. The sites burned between 1998 and 1850, and each contained separate well- and poorly drained stands. All components of NPP were measured, most for 3 consecutive years. Total NPP was low (50‐100gCm � 2 yr � 1 ) immediately after fire, highest 12‐20 years after fire (332 and 521gCm � 2 yr � 1 in the dry and wet stands, respectively) but 50% lower than this in the oldest stands. Tree NPP was highest 37 years after fire but 16‐ 39% lower in older stands, and was dominated by deciduous seedlings in the young stands and by black spruce trees (485%) in the older stands. The chronosequence was unreplicated but these results were consistent with 14 secondary sites sampled across the landscape. Bryophytes comprised a large percentage of aboveground NPP in the poorly drained stands, while belowground NPP was 0‐40% of total NPP. Interannual NPP variability was greater in the youngest stands, the poorly drained stands, and for understory and detritus Production. Net Ecosystem Production (NEP), calculated using heterotrophic soil and woody debris respiration data from previous studies in this chronosequence, implied that the youngest stands were moderate C sources (roughly, 100gC m � 2 yr � 1 ), the middle-aged stands relatively strong sinks (100‐300gCm � 2 yr � 1 ), and the oldest stands about neutral with respect to the atmosphere. The Ecosystem approach employed in this study provided realistic estimates of chronosequence NPP and NEP, demonstrated the profound impact of wildfire on forest‐atmosphere C exchange, and emphasized the need to account for soil drainage, bryophyte Production, and species succession when modeling boreal forest C fluxes.
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Net primary Production and Net Ecosystem Production of a boreal black spruce wildfire chronosequence
Global Change Biology, 2004Co-Authors: Ben Bondlamberty, Chuankuan Wang, Stith T GowerAbstract:Net primary Production (NPP) was measured in seven black spruce (Picea mariana (Mill.) BSP)-dominated sites comprising a boreal forest chronosequence near Thompson, Man., Canada. The sites burned between 1998 and 1850, and each contained separate well- and poorly drained stands. All components of NPP were measured, most for 3 consecutive years. Total NPP was low (50‐100gCm � 2 yr � 1 ) immediately after fire, highest 12‐20 years after fire (332 and 521gCm � 2 yr � 1 in the dry and wet stands, respectively) but 50% lower than this in the oldest stands. Tree NPP was highest 37 years after fire but 16‐ 39% lower in older stands, and was dominated by deciduous seedlings in the young stands and by black spruce trees (485%) in the older stands. The chronosequence was unreplicated but these results were consistent with 14 secondary sites sampled across the landscape. Bryophytes comprised a large percentage of aboveground NPP in the poorly drained stands, while belowground NPP was 0‐40% of total NPP. Interannual NPP variability was greater in the youngest stands, the poorly drained stands, and for understory and detritus Production. Net Ecosystem Production (NEP), calculated using heterotrophic soil and woody debris respiration data from previous studies in this chronosequence, implied that the youngest stands were moderate C sources (roughly, 100gC m � 2 yr � 1 ), the middle-aged stands relatively strong sinks (100‐300gCm � 2 yr � 1 ), and the oldest stands about neutral with respect to the atmosphere. The Ecosystem approach employed in this study provided realistic estimates of chronosequence NPP and NEP, demonstrated the profound impact of wildfire on forest‐atmosphere C exchange, and emphasized the need to account for soil drainage, bryophyte Production, and species succession when modeling boreal forest C fluxes.
Stith T Gower - One of the best experts on this subject based on the ideXlab platform.
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Net primary Production and Net Ecosystem Production of a boreal black spruce wildfire chronosequence
Global Change Biology, 2004Co-Authors: Ben Bondlamberty, Chuankuan Wang, Stith T GowerAbstract:Net primary Production (NPP) was measured in seven black spruce (Picea mariana (Mill.) BSP)-dominated sites comprising a boreal forest chronosequence near Thompson, Man., Canada. The sites burned between 1998 and 1850, and each contained separate well- and poorly drained stands. All components of NPP were measured, most for 3 consecutive years. Total NPP was low (50‐100gCm � 2 yr � 1 ) immediately after fire, highest 12‐20 years after fire (332 and 521gCm � 2 yr � 1 in the dry and wet stands, respectively) but 50% lower than this in the oldest stands. Tree NPP was highest 37 years after fire but 16‐ 39% lower in older stands, and was dominated by deciduous seedlings in the young stands and by black spruce trees (485%) in the older stands. The chronosequence was unreplicated but these results were consistent with 14 secondary sites sampled across the landscape. Bryophytes comprised a large percentage of aboveground NPP in the poorly drained stands, while belowground NPP was 0‐40% of total NPP. Interannual NPP variability was greater in the youngest stands, the poorly drained stands, and for understory and detritus Production. Net Ecosystem Production (NEP), calculated using heterotrophic soil and woody debris respiration data from previous studies in this chronosequence, implied that the youngest stands were moderate C sources (roughly, 100gC m � 2 yr � 1 ), the middle-aged stands relatively strong sinks (100‐300gCm � 2 yr � 1 ), and the oldest stands about neutral with respect to the atmosphere. The Ecosystem approach employed in this study provided realistic estimates of chronosequence NPP and NEP, demonstrated the profound impact of wildfire on forest‐atmosphere C exchange, and emphasized the need to account for soil drainage, bryophyte Production, and species succession when modeling boreal forest C fluxes.
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Net primary Production and Net Ecosystem Production of a boreal black spruce wildfire chronosequence
Global Change Biology, 2004Co-Authors: Ben Bondlamberty, Chuankuan Wang, Stith T GowerAbstract:Net primary Production (NPP) was measured in seven black spruce (Picea mariana (Mill.) BSP)-dominated sites comprising a boreal forest chronosequence near Thompson, Man., Canada. The sites burned between 1998 and 1850, and each contained separate well- and poorly drained stands. All components of NPP were measured, most for 3 consecutive years. Total NPP was low (50‐100gCm � 2 yr � 1 ) immediately after fire, highest 12‐20 years after fire (332 and 521gCm � 2 yr � 1 in the dry and wet stands, respectively) but 50% lower than this in the oldest stands. Tree NPP was highest 37 years after fire but 16‐ 39% lower in older stands, and was dominated by deciduous seedlings in the young stands and by black spruce trees (485%) in the older stands. The chronosequence was unreplicated but these results were consistent with 14 secondary sites sampled across the landscape. Bryophytes comprised a large percentage of aboveground NPP in the poorly drained stands, while belowground NPP was 0‐40% of total NPP. Interannual NPP variability was greater in the youngest stands, the poorly drained stands, and for understory and detritus Production. Net Ecosystem Production (NEP), calculated using heterotrophic soil and woody debris respiration data from previous studies in this chronosequence, implied that the youngest stands were moderate C sources (roughly, 100gC m � 2 yr � 1 ), the middle-aged stands relatively strong sinks (100‐300gCm � 2 yr � 1 ), and the oldest stands about neutral with respect to the atmosphere. The Ecosystem approach employed in this study provided realistic estimates of chronosequence NPP and NEP, demonstrated the profound impact of wildfire on forest‐atmosphere C exchange, and emphasized the need to account for soil drainage, bryophyte Production, and species succession when modeling boreal forest C fluxes.
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Net Ecosystem Production of two contrasting boreal black spruce forest communities
Ecosystems, 2003Co-Authors: Kari Oconnell, Stith T Gower, John M. NormanAbstract:The objective of this study was to compare the carbon (C) budgets of two similar-aged boreal black spruce (Picea mariana [Mill.] BSP) forest communities: closed-canopy black spruce with feathermoss ground cover (BSFM) on moderately drained soils and open-canopy black spruce with Sphagnum ground cover (BSSP) on poorly drained soils. C content, soil surface carbon dioxide (CO 2 ) flux (R s ), heterotrophic respiration (R H ), Net primary Production (NPP), and Net Ecosystem Production (NEP) were measured or estimated. The total C content for the two communities (BSFM, 113 Mg C ha -1 ; BSSP, 107 Mg C ha -1 ) did not differ significantly (P = 0.95). However, annual R s was significantly greater (P < 0.0001) for the BSFM (564 g C m -2 y -1 ) than the BSSP (319 g C m -2 y -1 ) community. The greater R H in the BSFM (440 g C m -2 y -1 ) than the BSSP community (264 g C m -2 y -1 ) and the higher peat C content for the BSSP (84 Mg C ha -1 ) than the BSFM (34 Mg C ha -1 ) community provided evidence that the BSSP community had a lower decomposition rate than the BSFM community. NEP was significantly (P = 0.04) more negative for the BSFM community (-222 ± 35 g C m -2 y -1 ) than the BSSP community (-128 ± 14 g C m -2 y -1 ), but both communities were C sources to the atmosphere. The results from this study illustrate the influence of small differences in edaphic conditions on Ecosystem C accumulation.
David P Turner - One of the best experts on this subject based on the ideXlab platform.
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a large proportion of north american Net Ecosystem Production is offset by emissions from harvested products river stream evasion and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO2 evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO2 concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 370 TgC yr 1 (a carbon sink). Harvested product emissions (316 80 TgC yr 1 ), river/stream evasion (158 50 TgC yr 1 ), and fire emissions (142 45 TgC yr 1 ) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO2 concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.
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A large proportion of North American Net Ecosystem Production is offset by emissions from harvested products, river/stream evasion, and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO2 evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO2 concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 370 TgC yr 1 (a carbon sink). Harvested product emissions (316 80 TgC yr 1 ), river/stream evasion (158 50 TgC yr 1 ), and fire emissions (142 45 TgC yr 1 ) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO2 concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.
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A large proportion of North American Net Ecosystem Production is offset by emissions from harvested products, river/stream evasion, and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.\ud The published article is copyrighted by Wiley-Blackwell and can be found at: http://onlinelibrary.wiley.com/.Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production\ud and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface\ud vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of\ud Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the\ud vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions\ud from decomposition/respiration of harvested forest and agricultural products, CO₂ evasion from streams and\ud rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that\ud includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker\ud inversion setup to evaluate its consistency with CO₂ concentration observations. The year 2004 was climatologically\ud favorable for NEP over North America and the continental total was estimated at 1730± 370 TgC yr\ud ⁻¹ (a\ud carbon sink). Harvested product emissions (316 ± 80 TgC yr\ud ⁻ ¹), river/stream evasion (158 ± 50 TgC yr\ud ⁻¹), and fire\ud emissions (142 ± 45 TgC yr\ud ⁻¹) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong\ud carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest.\ud The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime\ud CO₂ concentrations aggregated over eight measurement sites around North America, but overestimates of\ud summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is\ud the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation\ud – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle
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decadal trends in Net Ecosystem Production and Net Ecosystem carbon balance for a regional socioecological system
Forest Ecology and Management, 2011Co-Authors: David P Turner, William D. Ritts, Robert E Kennedy, Warren B Cohen, Matthew Duane, Zhiqiang Yang, Peter E ThorntonAbstract:Carbon sequestration is increasingly recognized as an Ecosystem service, and forest management has a large potential to alter regional carbon fluxes notably by way of harvest removals and related impacts on Net Ecosystem Production (NEP). In the Pacific Northwest region of the US, the implementation of the Northwest Forest Plan (NWFP) in 1993 established a regional socioecological system focused on forest management. The NWFP resulted in a large (82%) decrease in the rate of harvest removals on public forest land, thus significantly impacting the regional carbon balance. Here we use a combination of remote sensing and Ecosystem modeling to examine the trends in NEP and Net Ecosystem carbon balance (NECB) in this region over the 1985-2007 period, with particular attention to land ownership since management now differs widely between public and private forestland. In the late 1980s, forestland in both ownership classes was subject to high rates of harvesting, and consequently the land was a carbon source (i.e. had a negative NECB). After the policy driven reduction in the harvest level, public forestland became a large carbon sink driven in part by increasing NEP whereas private forestland was close to carbon neutral. In the 2003-2007 period, the trend towards carbon accumulation on public lands continued despite a moderate increase in the extent of wildfire. The NWFP was originally implemented in the context of bio- diversity conservation, but its consequences in terms of carbon sequestration are also of societal interest. Ultimately, management within the NWFP socioecological system will have to consider trade-offs among these and other Ecosystem services.
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landscape scale simulation of heterogeneous fire effects on pyrogenic carbon emissions tree mortality and Net Ecosystem Production
Ecosystems, 2011Co-Authors: Garrett W Meigs, William D. Ritts, David P Turner, Zhiqiang YangAbstract:Fire influences carbon dynamics from local to global scales, but many uncertainties remain regarding the remote detection and simulation of heterogeneous fire effects. This study integrates Landsat-based remote sensing and Biome-BGC process modeling to simulate the effects of high-, moderate-, and low-severity fire on pyrogenic emissions, tree mortality, and Net Ecosystem Production. The simulation area (244,600 ha) encompasses four fires that burned approximately 50,000 ha in 2002–2003 across the Metolius Watershed, Oregon, USA, as well as in situ measurements of postfire carbon pools and fluxes that we use for model evaluation. Simulated total pyrogenic emissions were 0.732 Tg C (2.4% of equivalent statewide anthropogenic carbon emissions over the same 2-year period). The simulated total carbon transfer due to tree mortality was fourfold higher than pyrogenic carbon emissions, but dead wood decomposition will occur over decades. Immediately postfire, burned areas were a simulated carbon source (Net C exchange: −0.076 Tg C y−1; mean ± SD: −142 ± 121 g C m−2 y−1). As expected, high-severity, stand-replacement fire had disproportionate carbon impacts. The per-unit area effects of moderate-severity fire were substantial, however, and the extent of low-severity fire merits its inclusion in landscape-scale analyses. These results demonstrate the potential to reduce uncertainties in landscape to regional carbon budgets by leveraging Landsat-based fire products that account for both stand-replacement and partial disturbance.
William D. Ritts - One of the best experts on this subject based on the ideXlab platform.
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a large proportion of north american Net Ecosystem Production is offset by emissions from harvested products river stream evasion and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO2 evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO2 concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 370 TgC yr 1 (a carbon sink). Harvested product emissions (316 80 TgC yr 1 ), river/stream evasion (158 50 TgC yr 1 ), and fire emissions (142 45 TgC yr 1 ) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO2 concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.
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A large proportion of North American Net Ecosystem Production is offset by emissions from harvested products, river/stream evasion, and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO2 evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO2 concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 370 TgC yr 1 (a carbon sink). Harvested product emissions (316 80 TgC yr 1 ), river/stream evasion (158 50 TgC yr 1 ), and fire emissions (142 45 TgC yr 1 ) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO2 concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.
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A large proportion of North American Net Ecosystem Production is offset by emissions from harvested products, river/stream evasion, and biomass burning
Global Change Biology, 2013Co-Authors: David P Turner, William D. Ritts, A R Jacobson, Weile L Wang, Ramakrishna R. NemaniAbstract:To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.\ud The published article is copyrighted by Wiley-Blackwell and can be found at: http://onlinelibrary.wiley.com/.Diagnostic carbon cycle models produce estimates of Net Ecosystem Production (NEP, the balance of Net primary Production\ud and heterotrophic respiration) by integrating information from (i) satellite-based observations of land surface\ud vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of\ud Net Ecosystem exchange (NEE) (used in model parameterization). However, a full bottom-up accounting of NEE (the\ud vertical carbon flux) that is suitable for integration with atmosphere-based inversion modeling also includes emissions\ud from decomposition/respiration of harvested forest and agricultural products, CO₂ evasion from streams and\ud rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that\ud includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker\ud inversion setup to evaluate its consistency with CO₂ concentration observations. The year 2004 was climatologically\ud favorable for NEP over North America and the continental total was estimated at 1730± 370 TgC yr\ud ⁻¹ (a\ud carbon sink). Harvested product emissions (316 ± 80 TgC yr\ud ⁻ ¹), river/stream evasion (158 ± 50 TgC yr\ud ⁻¹), and fire\ud emissions (142 ± 45 TgC yr\ud ⁻¹) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong\ud carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest.\ud The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime\ud CO₂ concentrations aggregated over eight measurement sites around North America, but overestimates of\ud summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is\ud the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation\ud – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle
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decadal trends in Net Ecosystem Production and Net Ecosystem carbon balance for a regional socioecological system
Forest Ecology and Management, 2011Co-Authors: David P Turner, William D. Ritts, Robert E Kennedy, Warren B Cohen, Matthew Duane, Zhiqiang Yang, Peter E ThorntonAbstract:Carbon sequestration is increasingly recognized as an Ecosystem service, and forest management has a large potential to alter regional carbon fluxes notably by way of harvest removals and related impacts on Net Ecosystem Production (NEP). In the Pacific Northwest region of the US, the implementation of the Northwest Forest Plan (NWFP) in 1993 established a regional socioecological system focused on forest management. The NWFP resulted in a large (82%) decrease in the rate of harvest removals on public forest land, thus significantly impacting the regional carbon balance. Here we use a combination of remote sensing and Ecosystem modeling to examine the trends in NEP and Net Ecosystem carbon balance (NECB) in this region over the 1985-2007 period, with particular attention to land ownership since management now differs widely between public and private forestland. In the late 1980s, forestland in both ownership classes was subject to high rates of harvesting, and consequently the land was a carbon source (i.e. had a negative NECB). After the policy driven reduction in the harvest level, public forestland became a large carbon sink driven in part by increasing NEP whereas private forestland was close to carbon neutral. In the 2003-2007 period, the trend towards carbon accumulation on public lands continued despite a moderate increase in the extent of wildfire. The NWFP was originally implemented in the context of bio- diversity conservation, but its consequences in terms of carbon sequestration are also of societal interest. Ultimately, management within the NWFP socioecological system will have to consider trade-offs among these and other Ecosystem services.
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landscape scale simulation of heterogeneous fire effects on pyrogenic carbon emissions tree mortality and Net Ecosystem Production
Ecosystems, 2011Co-Authors: Garrett W Meigs, William D. Ritts, David P Turner, Zhiqiang YangAbstract:Fire influences carbon dynamics from local to global scales, but many uncertainties remain regarding the remote detection and simulation of heterogeneous fire effects. This study integrates Landsat-based remote sensing and Biome-BGC process modeling to simulate the effects of high-, moderate-, and low-severity fire on pyrogenic emissions, tree mortality, and Net Ecosystem Production. The simulation area (244,600 ha) encompasses four fires that burned approximately 50,000 ha in 2002–2003 across the Metolius Watershed, Oregon, USA, as well as in situ measurements of postfire carbon pools and fluxes that we use for model evaluation. Simulated total pyrogenic emissions were 0.732 Tg C (2.4% of equivalent statewide anthropogenic carbon emissions over the same 2-year period). The simulated total carbon transfer due to tree mortality was fourfold higher than pyrogenic carbon emissions, but dead wood decomposition will occur over decades. Immediately postfire, burned areas were a simulated carbon source (Net C exchange: −0.076 Tg C y−1; mean ± SD: −142 ± 121 g C m−2 y−1). As expected, high-severity, stand-replacement fire had disproportionate carbon impacts. The per-unit area effects of moderate-severity fire were substantial, however, and the extent of low-severity fire merits its inclusion in landscape-scale analyses. These results demonstrate the potential to reduce uncertainties in landscape to regional carbon budgets by leveraging Landsat-based fire products that account for both stand-replacement and partial disturbance.
Hiroshi Koizumi - One of the best experts on this subject based on the ideXlab platform.
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Carbon cycling and Net Ecosystem Production at an early stage of secondary succession in an abandoned coppice forest
Journal of Plant Research, 2010Co-Authors: Toshiyuki Ohtsuka, Yoko Shizu, Yuichiro Yashiro, Ai Nishiwaki, Hiroshi KoizumiAbstract:Secondary mixed forests are one of the dominant forest cover types in human-dominated temperate regions. However, our understanding of how secondary succession affects carbon cycling and carbon sequestration in these Ecosystems is limited. We studied carbon cycling and Net Ecosystem Production (NEP) over 4 years (2004–2008) in a cool-temperate deciduous forest at an early stage of secondary succession (18 years after clear-cutting). Net primary Production of the 18-year-old forest in this study was 5.2 tC ha^−1 year^−1, including below-ground coarse roots; this was partitioned into 2.5 tC ha^−1 year^−1 biomass increment, 1.6 tC ha^−1 year^−1 foliage litter, and 1.0 tC ha^−1 year^−1 other woody detritus. The total amount of annual soil surface CO_2 efflux was 6.8 tC ha^−1 year^−1, which included root respiration (1.9 tC ha^−1 year^−1) and heterotrophic respiration (RH) from soils (4.9 tC ha^−1 year^−1). The 18-year forest at this study site exhibited a great increase in biomass pool as a result of considerable total tree growth and low mortality of tree stems. In contrast, the soil organic matter (SOM) pool decreased markedly (−1.6 tC ha^−1 year^−1), although further study of below-ground detritus Production and RH of SOM decomposition is needed. This young 18-year forest was a weak carbon sink (0.9 tC ha^−1 year^−1) at this stage of secondary succession. The NEP of this 18-year forest is likely to increase gradually because biomass increases with tree growth and with the improvement of the SOM pool through increasing litter and dead wood Production with stand development.
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biometric based estimation of Net Ecosystem Production in a mature japanese cedar cryptomeria japonica plantation beneath a flux tower
Journal of Plant Research, 2010Co-Authors: Yuichiro Yashiro, Yoko Shizu, Taku M Saitoh, Toshiyuki Ohtsuka, Hiroshi KoizumiAbstract:Quantification of carbon budgets and cycling in Japanese cedar (Cryptomeria japonica D. Don) plantations is essential for understanding forest functions in Japan because these plantations occupy about 20% of the total forested area. We conducted a biometric estimate of Net Ecosystem Production (NEP) in a mature Japanese cedar plantation beneath a flux tower over a 4-year period. Net primary Production (NPP) was 7.9 Mg C ha−1 year−1 and consisted mainly of tree biomass increment and aboveground litter Production. Respiration was calculated as 6.8 (soil) and 3.3 (root) Mg C ha−1 year−1. Thus, NEP in the plantation was 4.3 Mg C ha−1 year−1. In agreement with the tower-based flux findings, this result suggests that the Japanese cedar plantation was a strong carbon sink. The biometric-based NEP was higher among most other types of Japanese forests studied. Carbon sequestration in the mature plantation was characterized by a larger increment in tree biomass and lower mortality than in natural forests. Land-use change from natural forest to Japanese cedar plantation might, therefore, stimulate carbon sequestration and change the carbon allocation of NPP from an increment in coarse woody debris to an increase in tree biomass.
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measurement of Net Ecosystem Production and Ecosystem respiration in a zoysia japonica grassland central japan by the chamber method
Ecological Research, 2010Co-Authors: Deepa Dhital, Hiroyuki Muraoka, Yuichiro Yashiro, Yoko Shizu, Hiroshi KoizumiAbstract:Measuring light, temperature, soil moisture, and growth provides a better understanding of Net Ecosystem Production (NEP), Ecosystem respiration (Reco), and their response functions. Here, we studied the variations in NEP and Reco in a grassland dominated by a perennial warm-season C4 grass, Zoysia japonica. We used the chamber method to measure NEP and Reco from August to September 2007. Biomass and leaf area index (LAI) were also measured to observe their effects on NEP and Reco. Diurnal variations in NEP and Reco were predicted well by light intensity (PPFD) and by soil temperature, respectively. Maximum NEP (NEPmax) values on days of year 221, 233, 247, and 262, were 2.44, 2.55, 3.90, and 4.17 μmol m−2 s−1, respectively. Throughout the growing period, the apparent quantum yield (α) increased with increasing NEPmax that ranged from 0.0154 to 0.0515, and NEP responded to the soil temperature changes by 44% and Reco changes by 48%, and Reco responded from 88 to 94% with the soil temperature diurnally. NEP’s light response and Reco’s temperature response were affected by soil water content; more than 27% of the variation in NEP and 67% of the variation in Reco could be explained by this parameter. NEP was strongly correlated with biomass and LAI, but Reco was not, because environmental variables affected Reco more strongly than growth parameters. Using the light response of NEP, the temperature response of Reco, and meteorological data, daily NEP and Reco were estimated at 0.67, 0.81, 1.17, and 1.56 g C m−2, and at 2.88, 2.50, 3.51, and 3.04 g C m−2, respectively, on days of year 221, 233, 247, and 262. The corresponding daily gross primary Production (NEP + Reco) was 3.5, 3.3, 4.6, and 4.6 g C m−2.
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seasonal shift in factors controlling Net Ecosystem Production in a high arctic terrestrial Ecosystem
Journal of Plant Research, 2010Co-Authors: Masaki Uchida, Ayaka Kishimoto, Hiroyuki Muraoka, Takayuki Nakatsubo, Hiroshi Kanda, Hiroshi KoizumiAbstract:We examined factors controlling temporal changes in Net Ecosystem Production (NEP) in a high Arctic polar semi-desert Ecosystem in the snow-free season. We examined the relationships between NEP and biotic and abiotic factors in a dominant plant community (Salix polaris–moss) in the Norwegian high Arctic. Just after snowmelt in early July, the Ecosystem released CO2 into the atmosphere. A few days after snowmelt, however, the Ecosystem became a CO2 sink as the leaves of S. polaris developed. Diurnal changes in NEP mirrored changes in light incidence (photosynthetic photon flux density, PPFD) in summer. NEP was significantly correlated with PPFD when S. polaris had fully developed leaves, i.e., high photosynthetic activity. In autumn, NEP values decreased as S. polaris underwent senescence. During this time, CO2 was sometimes released into the atmosphere. In wet conditions, moss made a larger contribution to NEP. In fact, the water content of the moss regulated NEP during autumn. Our results indicate that the main factors controlling NEP in summer are coverage and growth of S. polaris, PPFD, and precipitation. In autumn, the main factor controlling NEP is moss water content.
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On linking multiyear biometric measurements of tree growth with eddy covariance‐based Net Ecosystem Production
Global Change Biology, 2009Co-Authors: Toshiyuki Ohtsuka, Nobuko Saigusa, Hiroshi KoizumiAbstract:Annual measurements of the diameter growth and litter fall of trees began in 1998 using a 1.0 ha permanent plot beneath a flux tower at the Takayama flux site, central Japan. This opened up an opportunity for studies that compare the interannual variability in tree growth with eddy covariance-based Net Ecosystem Production (NEP). A possible link between multiyear biometric-based Net primary Production (NPP) and eddy covariance-based NEP was investigated to determine the contribution of autotrophic Production and heterotrophic respiration (HR) to the interannual variability of NEP in deciduous forest Ecosystems. We also defined the NEP* as the measurable organic matter stored in an Ecosystem during the interval in which soil respiration (SR) measurements were taken. The difference of biometric-based NEP* from eddy covariance-based NEP within a given year varied between 55% and 105%. Woody tissue NPP (stems and coarse roots) varied markedly from 0.88 to 1.96 Mg C ha -1 yr -1 during the 8-year study period (1999-2006). Annual woody tissue NPP was positively correlated with eddy covariance-based NEP (r 2 =0.52, P
