scholarly journals Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

2012 ◽  
Vol 9 (7) ◽  
pp. 9667-9710 ◽  
Author(s):  
M. Wilkinson ◽  
E. L. Eaton ◽  
M. S. J. Broadmeadow ◽  
J. I. L. Morison
Keyword(s):  
Carbon Balance ◽  
Forest Canopy ◽  
Annual Variation ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Co2 Uptake ◽  
Operophtera Brumata ◽  
Area Index ◽  
Growing Season Length ◽  
Net Co2 Uptake

Abstract. The carbon balance of an 80 yr old deciduous oak plantation in the temperate oceanic climate of the south-east of Britain was measured by eddy covariance over 12 yr (1999–2010). The mean annual net ecosystem productivity (NEP) was 486 g C m−2 y−1 (95% CI of ±73 g C m−2 y−1), and this was partitioned into a Gross Primary Productivity (GPP) of 2034 ± 145 g C m−2 y−1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m−2 y−1. The interannual variation of NEP was large (coefficient of variation (CV) 23%), although the variation for GPP and Reco was smaller (12%) and the ratio of Reco/GPP was relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular combinations of anomalous weather events, such as high summer air temperature and low soil moisture content. The Europe-wide heat-wave and drought of 2003 had little effect on the C balance of this woodland on a surface water gley soil. Annual variation in precipitation (CV 18%) was not a main factor in the variation in NEP. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p<0.001) was found between peak leaf area index and annual GPP which in turn played an important role in modifying the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days, respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these years.

scholarly journals Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

2012 ◽  
Vol 9 (12) ◽  
pp. 5373-5389 ◽  
Author(s):  
M. Wilkinson ◽  
E. L. Eaton ◽  
M. S. J. Broadmeadow ◽  
J. I. L. Morison
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Eddy Covariance ◽  
Carbon Balance ◽  
Annual Variation ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Co2 Uptake ◽  
Growing Season Length ◽  
Net Co2 Uptake

Abstract. The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999–2010). The mean annual net ecosystem productivity (NEP) was 486 g C m−2 yr−1 (95% CI of ±73 g C m−2 yr−1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m−2 yr−1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m−2 yr−1. Although the maximum variation of NEP between years was large (333 g C m−2 yr−1), the ratio of Reco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p < 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest was a substantial sink of carbon over the 12-yr measurement period.

scholarly journals Land use affects the net ecosystem CO<sub>2</sub> exchange and its components in mountain grasslands

2010 ◽  
Vol 7 (8) ◽  
pp. 2297-2309 ◽  
Author(s):  
M. Schmitt ◽  
M. Bahn ◽  
G. Wohlfahrt ◽  
U. Tappeiner ◽  
A. Cernusca
Keyword(s):  
Land Use ◽  
Leaf Area ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Photon Flux ◽  
Area Index ◽  
Growing Season Length ◽  
Mountain Grassland ◽  
Mountain Grasslands ◽  
Land Use And Management

Abstract. Changes in land use and management have been strongly affecting mountain grassland, however, their effects on the net ecosystem exchange of CO2 (NEE) and its components have not yet been well documented. We analysed chamber-based estimates of NEE, gross primary productivity (GPP), ecosystem respiration (R) and light use efficiency (LUE) of six mountain grasslands differing in land use and management, and thus site fertility, for the growing seasons of 2002 to 2008. The main findings of the study are that: (1) land use and management affected seasonal NEE, GPP and R, which all decreased from managed to unmanaged grasslands; (2) these changes were explained by differences in leaf area index (LAI), biomass and leaf-area-independent changes that were likely related to photosynthetic physiology; (3) diurnal variations of NEE were primarily controlled by photosynthetically active photon flux density and soil and air temperature; seasonal variations were associated with changes in LAI; (4) parameters of light response curves were generally closely related to each other, and the ratio of R at a reference temperature/ maximum GPP was nearly constant across the sites; (5) similarly to our study, maximum GPP and R for other grasslands on the globe decreased with decreasing land use intensity, while their ratio remained remarkably constant. We conclude that decreasing intensity of management and, in particular, abandonment of mountain grassland lead to a decrease in NEE and its component processes. While GPP and R are generally closely coupled during most of the growing season, GPP is more immediately and strongly affected by land management (mowing, grazing) and season. This suggests that management and growing season length, as well as their possible future changes, may play an important role for the annual C balance of mountain grassland.

scholarly journals Biophysical controls on net ecosystem CO<sub>2</sub> exchange over a semiarid shrubland in northwest China

2014 ◽  
Vol 11 (3) ◽  
pp. 5089-5122 ◽  
Author(s):  
X. Jia ◽  
T. S. Zha ◽  
B. Wu ◽  
Y. Q. Zhang ◽  
J. N. Gong ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Growing Season ◽  
C Sequestration ◽  
Northwest China ◽  
Wide Distribution ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Area Index ◽  
C Cycling ◽  
Sequestration Potential

Abstract. The carbon (C) cycling in semiarid and arid areas remains largely unexplored, despite the wide distribution of drylands globally. Rehabilitation practices have been carried out in many desertified areas, but information on the C sequestration potential of recovering vegetation is still largely lacking. Using the eddy-covariance technique, we measured the net ecosystem CO2 exchange (NEE) over a recovering shrub ecosystem in northwest China throughout 2012 in order to (1) quantify NEE and its components, (2) examine the dependence of C fluxes on biophysical factors at multiple timescales. The annual budget showed a gross ecosystem productivity (GEP) of 456 ± 8 g C m−2 yr−1 and an ecosystem respiration (Re) of 379 ± 3 g C m−2 yr−1, resulting in a net C sink of 77 ± 7 g C m−2 yr−1. The maximum daily NEE, GEP and Re were −4.7, 6.8 and 3.3 g C m−2 day−1, respectively. Both the maximum C assimilation rate (i.e., at optimum light intensity) and the quantum yield varied strongly over the growing season, being higher in summer and lower in spring and autumn. At the half-hourly scale, water stress exerted a major control over daytime NEE, and interacted with heat stress and photoinhibition in constraining C fixation by the vegetation. Low soil moisture also reduced the temperature sensitivity of Re (Q10). At the synoptic scale, rain events triggered immediate pulses of C release from the ecosystem, followed by peaks of CO2 uptake 1–2 days later. Over the entire growing season, leaf area index accounted for 45 and 65% of the seasonal variation in NEE and GEP, respectively. There was a linear dependence of daily Re on GEP, with a slope of 0.34. These results highlight the role of abiotic stresses and their alleviation in regulating C cycling in the face of an increasing frequency and intensity of extreme climatic events.

scholarly journals Biophysical controls on net ecosystem CO<sub>2</sub> exchange over a semiarid shrubland in northwest China

2014 ◽  
Vol 11 (17) ◽  
pp. 4679-4693 ◽  
Author(s):  
X. Jia ◽  
T. S. Zha ◽  
B. Wu ◽  
Y. Q. Zhang ◽  
J. N. Gong ◽  
...  
Keyword(s):  
Prediction Interval ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
C Sequestration ◽  
Northwest China ◽  
Wide Distribution ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Area Index ◽  
C Cycling

Abstract. The carbon (C) cycling in semiarid and arid areas remains largely unexplored, despite the wide distribution of drylands globally. Rehabilitation practices have been carried out in many desertified areas, but information on the C sequestration capacity of recovering vegetation is still largely lacking. Using the eddy-covariance technique, we measured the net ecosystem CO2 exchange (NEE) over a recovering shrub ecosystem in northwest China throughout 2012 in order to (1) quantify NEE and its components and to (2) examine the dependence of C fluxes on biophysical factors at multiple timescales. The annual budget showed a gross ecosystem productivity (GEP) of 456 g C m−2 yr−1 (with a 90% prediction interval of 449–463 g C m−2 yr−1) and an ecosystem respiration (Re) of 379 g C m−2 yr−1 (with a 90% prediction interval of 370–389 g C m−2 yr−1), resulting in a net C sink of 77 g C m−2 yr−1 (with a 90% prediction interval of 68–87 g C m−2 yr−1). The maximum daily NEE, GEP and Re were −4.7, 6.8 and 3.3 g C m−2 day−1, respectively. Both the maximum C assimilation rate (i.e., at the optimum light intensity) and the quantum yield varied over the growing season, being higher in summer and lower in spring and autumn. At the half-hourly scale, water deficit exerted a major control over daytime NEE, and interacted with other stresses (e.g., heat and photoinhibition) in constraining C fixation by the vegetation. Low soil moisture also reduced the temperature sensitivity of Re (Q10). At the synoptic scale, rain events triggered immediate pulses of C release from the ecosystem, followed by peaks of CO2 uptake 1–2 days later. Over the entire growing season, leaf area index accounted for 45 and 65% of the seasonal variation in NEE and GEP, respectively. There was a linear dependence of daily Re on GEP, with a slope of 0.34. These results highlight the role of abiotic stresses and their alleviation in regulating C cycling in the face of an increasing frequency and intensity of extreme climatic events.

scholarly journals Key canopy traits drive forest productivity

2012 ◽  
Vol 279 (1736) ◽  
pp. 2128-2134 ◽  
Author(s):  
Peter B. Reich
Keyword(s):  
Forest Canopy ◽  
Net Primary Productivity ◽  
Nitrogen Concentration ◽  
Canopy Structure ◽  
Terrestrial Ecosystem ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Mean Annual Temperature ◽  
Area Index ◽  
Growing Season Length

Quantifying the mechanistic links between carbon fluxes and forest canopy attributes will advance understanding of leaf-to-ecosystem scaling and its potential application to assessing terrestrial ecosystem metabolism. Important advances have been made, but prior studies that related carbon fluxes to multiple canopy traits are scarce. Herein, presenting data for 128 cold temperate and boreal forests across a regional gradient of 600 km and 5.4°C (from 2.4°C to 7.8°C) in mean annual temperature, I show that stand-scale productivity is a function of the capacity to harvest light (represented by leaf area index, LAI), and to biochemically fix carbon (represented by canopy nitrogen concentration, %N). In combination, LAI and canopy %N explain greater than 75 per cent of variation in above-ground net primary productivity among forests, expressed per year or per day of growing season. After accounting for growing season length and climate effects, less than 10 per cent of the variance remained unexplained. These results mirror similar relations of leaf-scale and canopy-scale (eddy covariance) maximum photosynthetic rates to LAI and %N. Collectively, these findings indicate that canopy structure and chemistry translate from instantaneous physiology to annual carbon fluxes. Given the increasing capacity to remotely sense canopy LAI, %N and phenology, these results support the idea that physiologically based scaling relations can be useful tools for global modelling.

scholarly journals Drainage reduces CO<sub>2</sub> uptake and increases CO<sub>2</sub> efflux by a Siberian floodplain due to shifts in vegetation community and soil thermal characteristics

2016 ◽  
Author(s):  
M. J. Kwon ◽  
M. Heimann ◽  
K. A. Luus ◽  
E. A. G. Schuur ◽  
N. Zimov ◽  
...  
Keyword(s):  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Thermal Characteristics ◽  
Growing Season ◽  
The Arctic ◽  
Co2 Uptake ◽  
Vegetation Community ◽  
Closed Chamber ◽  
Soil Temperatures ◽  
Net Co2 Uptake

Abstract. With increasing air temperatures and shifts in precipitation patterns forecasted in the Arctic over the coming decades, thawing of ice-rich permafrost is expected to change the hydrological conditions in large parts of the region by creating mosaics of wetter and drier areas. The objective of this study is to investigate how lowered water table depths of formerly wet floodplain ecosystems affect CO2 fluxes measured with a closed chamber syst em, focusing on the roles of changes in vegetation community structure and soil thermal characteristics. We found that a decade-long drainage significantly increased the abundance of shrubs but decreased that of Eriophorum angustifolium, which subsequently made Carex species dominant. These two changes had opposing influences on photosynthetic uptake during the growing season: increased abundance of shrubs slightly increased gross primary production while replacement of Eriophorum by Carex significantly decreased it. Drainage also diminishes the heat capacity and thermal conductivity of soil, leading to increased soil temperatures in shallow layers during the daytime and decreased soil temperatures in deeper layers, and therefore reduced thaw depths. This soil temperature regime can intensify growing-season ecosystem respiration by up to 93 % theoretically. Overall, drainage increased net CO2 uptake (net ecosystem exchange) by 16 % over 20 days in 2013 but decreased it by 37 % over 66 days in 2014. During the frozen season, the drained transect emitted four times more CO2 than the undrained transect. In summary, the net effect of these complex changes recently weakened net CO2 uptake in the drained areas.

scholarly journals Bulk partitioning the growing season net ecosystem exchange of CO<sub>2</sub> in Siberian tundra reveals the seasonality of its carbon sequestration strength

2012 ◽  
Vol 9 (10) ◽  
pp. 13713-13742 ◽  
Author(s):  
B. R. K. Runkle ◽  
T. Sachs ◽  
C. Wille ◽  
E.-M. Pfeiffer ◽  
L. Kutzbach
Keyword(s):  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
New Method ◽  
Apparent Temperature ◽  
The Arctic ◽  
Co2 Uptake ◽  
Night Time ◽  
Tundra Ecosystem ◽  
Co2 Sink

Abstract. This paper evaluates the relative contribution of light and temperature on net ecosystem CO2 uptake during the 2006 growing season in a~polygonal tundra ecosystem in the Lena River Delta in Northern Siberia (72°22´ N, 126°30´ E). We demonstrate that the timing of warm periods may be an important determinant of the magnitude of the ecosystem's carbon sink function, as they drive temperature-induced changes in respiration. Hot spells during the early portion of the growing season are shown to be more influential in creating mid-day surface-to-atmosphere net ecosystem CO2 exchange fluxes than those occurring later in the season. In this work we also develop and present a bulk flux partition model to better account for tundra plant physiology and the specific light conditions of the arctic region that preclude the successful use of traditional partition methods that derive a respiration-temperature relationship from all night-time data. Night-time, growing season measurements are rare during the arctic summer, however, so the new method allows for temporal variation in the parameters describing both ecosystem respiration and gross uptake by fitting both processes at the same time. Much of the apparent temperature sensitivity of respiration seen in the traditional partition method is revealed in the new method to reflect seasonal changes in basal respiration rates. Understanding and quantifying the flux partition is an essential precursor to describing links between assimilation and respiration at different time scales, as it allows a more confident evaluation of measured net exchange over a broader range of environmental conditions. The growing season CO2 sink estimated by this study is similar to those reported previously for this site, and is substantial enough to withstand the long, low-level respiratory CO2 release during the rest of the year to maintain the site's CO2 sink function on an annual basis.

scholarly journals Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan

2015 ◽  
Vol 12 (23) ◽  
pp. 6837-6851 ◽  
Author(s):  
K. Yamanoi ◽  
Y. Mizoguchi ◽  
H. Utsugi
Keyword(s):  
Forest Management ◽  
Carbon Balance ◽  
Deciduous Forest ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
White Birch ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Forests play an important role in the terrestrial carbon balance, with most being in a carbon sequestration stage. The net carbon releases that occur result from forest disturbance, and windthrow is a typical disturbance event affecting the forest carbon balance in eastern Asia. The CO2 flux has been measured using the eddy covariance method in a deciduous broadleaf forest (Japanese white birch, Japanese oak, and castor aralia) in Hokkaido, where incidental damage by the strong Typhoon Songda in 2004 occurred. We also used the biometrical method to demonstrate the CO2 flux within the forest in detail. Damaged trees amounted to 40 % of all trees, and they remained on site where they were not extracted by forest management. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production were 1350, 975, and 375 g C m−2 yr−1 before the disturbance and 1262, 1359, and −97 g C m−2 yr−1 2 years after the disturbance, respectively. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed into a net carbon source. Because of increased light intensity at the forest floor, the leaf area index and biomass of the undergrowth (Sasa kurilensis and S. senanensis) increased by factors of 2.4 and 1.7, respectively, in 3 years subsequent to the disturbance. The photosynthesis of Sasa increased rapidly and contributed to the total GPP after the disturbance. The annual GPP only decreased by 6 % just after the disturbance. On the other hand, the annual Re increased by 39 % mainly because of the decomposition of residual coarse-wood debris. The carbon balance after the disturbance was controlled by the new growth and the decomposition of residues. The forest management, which resulted in the dead trees remaining at the study site, strongly affected the carbon balance over the years. When comparing the carbon uptake efficiency at the study site with that at others, including those with various kinds of disturbances, we emphasized the importance of forest management as well as disturbance type in the carbon balance.

scholarly journals Annual carbon balance of a peatland 10 yr following restoration

2013 ◽  
Vol 10 (5) ◽  
pp. 2885-2896 ◽  
Author(s):  
M. Strack ◽  
Y. C. A. Zuback
Keyword(s):  
Carbon Balance ◽  
Ecosystem Respiration ◽  
Carbon Sources ◽  
Growing Season ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Winter Period ◽  
Peat Extraction ◽  
Annual Carbon ◽  
Annual Carbon Balance

Abstract. Undisturbed peatlands represent long-term net sinks of carbon; however, peat extraction converts these systems into large and persistent sources of greenhouse gases. Although rewetting and restoration following peat extraction have taken place over the last several decades, very few studies have investigated the longer term impact of this restoration on peatland carbon balance. We determined the annual carbon balance of a former horticulturally-extracted peatland restored 10 yr prior to the study and compared these values to the carbon balance measured at neighboring unrestored and natural sites. Carbon dioxide (CO2) and methane (CH4) fluxes were measured using the chamber technique biweekly during the growing season from May to October 2010 and three times over the winter period. Dissolved organic carbon (DOC) export was measured from remnant ditches in the unrestored and restored sites. During the growing season the restored site had greater uptake of CO2 than the natural site when photon flux density was greater than 1000 μmol m−2 s−1, while the unrestored site remained a source of CO2. Ecosystem respiration was similar between natural and restored sites, which were both significantly lower than the unrestored site. Methane flux remained low at the restored site except from open water pools, created as part of restoration, and remnant ditches. Export of DOC during the growing season was 5.0 and 28.8 g m−2 from the restored and unrestored sites, respectively. Due to dry conditions during the study year all sites acted as net carbon sources with annual balance of the natural, restored and unrestored sites of 250.7, 148.0 and 546.6 g C m−2, respectively. Although hydrological conditions and vegetation community at the restored site remained intermediate between natural and unrestored conditions, peatland restoration resulted in a large reduction in annual carbon loss from the system resulting in a carbon balance more similar to a natural peatland.

scholarly journals Seasonal variations in carbon dioxide exchange in an alpine wetland meadow on the Qinghai-Tibetan Plateau

2009 ◽  
Vol 6 (5) ◽  
pp. 9005-9044 ◽  
Author(s):  
L. Zhao ◽  
J. Li ◽  
S. Xu ◽  
H. Zhou ◽  
Y. Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Tibetan Plateau ◽  
Soil Temperature ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Research Station ◽  
Rain Event ◽  
Area Index ◽  
Alpine Wetland ◽  
Yearly Average

Abstract. The unique climate of the alpine wetland meadow is characterized by long cold winters and short cool summers with relatively high precipitation. These factors shorten the growing season for vegetation to approximately 150 to 165 days and prolong the dormant period to almost 7 months. Understanding how environmental variables affect the processes that regulate carbon flux in alpine wetland meadow on the Qinghai-Tibetan plateau is critical important because alpine wetland meadow plays a key role in the carbon cycle of the entire plateau. To address this issue, Gross Primary Production (GPP), Ecosystem Respiration (Reco), and Net Ecosystem CO2 Exchange (NEE) were examined for an alpine wetland meadow at the Haibei Research Station of the Chinese Academy of Sciences. The measurements covered three years and were made using the eddy covariance method. Seasonal trends of both GPP and Reco, followed closely changes in Leaf Area Index (LAI). Reco, exhibited the same exponential variation as soil temperature with seasonally-dependent R10 (the ecosystem respiration rate (μmol CO2 m−2 s−1) at the soil temperature reach 283.16 K (10°C)). Yearly average GPP, Reco, and NEE (which were 575.7, 676.8 and 101.1 gCm−2, respectively, for 2004 year, and 682.9, 726.4 and 44.0 gCm−2 for 2005 year, and 630.97, 808.2 and 173.2 gCm−2 for 2006 year) values indicated that the alpine wetland meadow was a moderately important source of CO2. The observed carbon dioxide fluxes in this alpine wetland meadow plateau are high in comparison with other alpine meadow environments such as Kobresia humilis meadow and shrubland meadow located in similar areas. And the cumulative NEE data indicated that the alpine wetland meadow is a source of atmospheric CO2 during the study years. CO2 emissions are large on elevated microclimatology areas on the meadow floor regardless of temperature. Furthermore, relatively low Reco, levels occurred during the non-growing season after a late rain event. This result is contradicted observations in alpine shrubland meadow. The timing of rain events had more impact on ecosystem GPP and NEE.

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