J W Harden
Dados Biográficos
| ID | 6436573 |
|---|---|
| NOME | J W Harden |
| PRENOMES | J W |
| SOBRENOME | Harden |
| ASSINATURA | HARDEN J W |
| AFILIAÇÕES | United States Geological Survey |
| ORCID | 0000-0002-6570-8259 |
| VERIFICADO | Sim |
| TOTAL DE OBRAS | 11 |
| TOTAL DE CITAÇÕES | 1 |
| TOTAL COMO AUTOR | 11 |
| TOTAL COMO EDITOR | 0 |
| PRIMEIRO ANO DE PUBLICAÇÃO | 1983 |
| ANO MAIS RECENTE DE PUBLICAÇÃO | 2017 |
| ÍNDICE H | 1 |
Soils and the Carbon Cycle
Soils currently store more than twice as much carbon as our current atmosphere and can sequester or release carbon dioxide (CO 2 ) through their capacity to store organic matter. This CO 2 exchange provides a service to the atmosphere through the regulation of CO 2 levels and their warming potential and to our ecosystems through the regulation of organic matter and its water and nutrient storage. Carbon stored in the soils of northern regions rep…
Climate change and the permafrost carbon feedback
Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remai…
Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps
Soils and other unconsolidated deposits in the northern circumpolar permafrost region store large amounts of soil organic carbon (SOC). This SOC is potentially vulnerable to remobilization following soil warming and permafrost thaw, but SOC stock estimates were poorly constrained and quantitative error estimates were lacking. This study presents revised estimates of permafrost SOC stocks, including quantitative uncertainty estimates, in the 0–3 m…
Effect of permafrost thaw on CO 2 and CH 4 exchange in a western Alaska peatland chronosequence
Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH _4 ), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO _2 ) and CH _4 exchange along sites that constitute a ∼1000 …
Controls on ecosystem and root respiration across a permafrost and wetland gradient in interior Alaska
Permafrost is common to many northern wetlands given the insulation of thick organic soil layers, although soil saturation in wetlands can lead to warmer soils and increased thaw depth. We analyzed five years of soil CO 2 fluxes along a wetland gradient that varied in permafrost and soil moisture conditions. We predicted that communities with permafrost would have reduced ecosystem respiration (ER) but greater temperature sensitivity than communi…
Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone
Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic factors were investigated using structural equation …
Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes
The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients wit…
The carbon budget of the northern cryosphere region
Isotopic Approach to Soil Carbonate Dynamics and Implications for Paleoclimatic Interpretations
The radiocarbon content and stable isotope composition of soil carbonate are best described by a dynamic system in which isotopic reequilibration occurs as a result of recurrent dissolution and reprecipitation. Depth of water penetration into the soil profile, as well as soil age, determines the degree of carbonate isotope reequilibration. We measured δ 13 C, δ 18 O and radiocarbon content of gravel rinds and fine ( 14 C yr B.P.) to assess the de…
Rates of Soil Development from Four Soil Chronosequences in the Southern Great Basin
Four soil chronosequences in the southern Great Basin were examined in order to study and quantify soil development during the Quaternary. Soils of all four areas are developed in gravelly alluvial fans in semiarid climates with 8 to 40 cm mean annual precipitation. Lithologies of alluvium are granite-gneiss at Silver Lake, granite and basalt at Cima Volcanic Field, limestone at Kyle Canyon, and siliceous volcanic rocks at Fortymile Wash. Ages of…
A Quantitative Comparison of Soil Development in Four Climatic Regimes
A new quantitative Soil Development Index based on field data has been applied to chronosequences formed under different climatic regimes. The four soil chronosequences, developed primarily on sandy deposits, have some numeric age control and are located in xeric-inland (Merced, Calif.), xeric-coastal (Ventura, Calif.), aridic (Las Cruces, N. Mex.), and udic (Susquehanna Valley, Pa.) soil-moisture regimes. To quantify field properties, points are…
A Quantitative Comparison of Soil Development in Four Climatic Regimes
A new quantitative Soil Development Index based on field data has been applied to chronosequences formed under different climatic regimes. The four soil chronosequences, developed primarily on sandy deposits, have some numeric age control and are located in xeric-inland (Merced, Calif.), xeric-coastal (Ventura, Calif.), aridic (Las Cruces, N. Mex.), and udic (Susquehanna Valley, Pa.) soil-moisture regimes. To quantify field properties, points are…
Rates of Soil Development from Four Soil Chronosequences in the Southern Great Basin
Four soil chronosequences in the southern Great Basin were examined in order to study and quantify soil development during the Quaternary. Soils of all four areas are developed in gravelly alluvial fans in semiarid climates with 8 to 40 cm mean annual precipitation. Lithologies of alluvium are granite-gneiss at Silver Lake, granite and basalt at Cima Volcanic Field, limestone at Kyle Canyon, and siliceous volcanic rocks at Fortymile Wash. Ages of…
Isotopic Approach to Soil Carbonate Dynamics and Implications for Paleoclimatic Interpretations
The radiocarbon content and stable isotope composition of soil carbonate are best described by a dynamic system in which isotopic reequilibration occurs as a result of recurrent dissolution and reprecipitation. Depth of water penetration into the soil profile, as well as soil age, determines the degree of carbonate isotope reequilibration. We measured δ 13 C, δ 18 O and radiocarbon content of gravel rinds and fine ( 14 C yr B.P.) to assess the de…
The carbon budget of the northern cryosphere region
Controls on ecosystem and root respiration across a permafrost and wetland gradient in interior Alaska
Permafrost is common to many northern wetlands given the insulation of thick organic soil layers, although soil saturation in wetlands can lead to warmer soils and increased thaw depth. We analyzed five years of soil CO 2 fluxes along a wetland gradient that varied in permafrost and soil moisture conditions. We predicted that communities with permafrost would have reduced ecosystem respiration (ER) but greater temperature sensitivity than communi…
Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone
Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic factors were investigated using structural equation …
Reorganization of vegetation, hydrology and soil carbon after permafrost degradation across heterogeneous boreal landscapes
The diversity of ecosystems across boreal landscapes, successional changes after disturbance and complicated permafrost histories, present enormous challenges for assessing how vegetation, water and soil carbon may respond to climate change in boreal regions. To address this complexity, we used a chronosequence approach to assess changes in vegetation composition, water storage and soil organic carbon (SOC) stocks along successional gradients wit…
Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps
Soils and other unconsolidated deposits in the northern circumpolar permafrost region store large amounts of soil organic carbon (SOC). This SOC is potentially vulnerable to remobilization following soil warming and permafrost thaw, but SOC stock estimates were poorly constrained and quantitative error estimates were lacking. This study presents revised estimates of permafrost SOC stocks, including quantitative uncertainty estimates, in the 0–3 m…
Effect of permafrost thaw on CO 2 and CH 4 exchange in a western Alaska peatland chronosequence
Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH _4 ), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO _2 ) and CH _4 exchange along sites that constitute a ∼1000 …
Climate change and the permafrost carbon feedback
Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remai…
Soils and the Carbon Cycle
Soils currently store more than twice as much carbon as our current atmosphere and can sequester or release carbon dioxide (CO 2 ) through their capacity to store organic matter. This CO 2 exchange provides a service to the atmosphere through the regulation of CO 2 levels and their warming potential and to our ecosystems through the regulation of organic matter and its water and nutrient storage. Carbon stored in the soils of northern regions rep…
Soil water (9 obras) · Environmental Science (8 obras) · Climate change and permafrost (7 obras) · Permafrost (7 obras) · Geology and Paleoclimatology Research (6 obras) · Geography (5 obras) · Geology (5 obras) · Geology (5 obras) · Peatlands and Wetlands Ecology (5 obras) · Soil carbon (5 obras)