scholarly journals Upside-down fluxes Down Under: CO<sub>2</sub> net sink in winter and net source in summer in a temperate evergreen broadleaf forest

2018 ◽  
Author(s):  
Alexandre A. Renchon ◽  
Anne Griebel ◽  
Christopher A. Williams ◽  
Belinda Medlyn ◽  
Remko A. Duursma ◽  
...  
Keyword(s):  
Large Scale ◽  
Ecosystem Respiration ◽  
Vapour Pressure Deficit ◽  
Summer Rainfall ◽  
Co2 Exchange ◽  
Mean Annual Precipitation ◽  
Surface Conductance ◽  
Mean Annual Temperature ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem-atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterized by a mean annual precipitation of 800 mm and a mean annual temperature of 18 °C, hot summers and mild winters, with highly variable precipitation. In the three-year study, the ecosystem was a small sink in 2014 (54 g C m−2 y−1), a stronger sink in 2015 (183 g C m−2 y−1) and even stronger sink in 2016 (337 g C m−2 y−1), but these variations were not related to precipitation. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was correlated with canopy leaf area index (LAI) (r2 = 0.24), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric drought and high temperature, and ecosystem respiration could be enhanced by rising temperature, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.

scholarly journals Upside-down fluxes Down Under: CO<sub>2</sub> net sink in winter and net source in summer in a temperate evergreen broadleaf forest

2018 ◽  
Vol 15 (12) ◽  
pp. 3703-3716 ◽  
Author(s):  
Alexandre A. Renchon ◽  
Anne Griebel ◽  
Daniel Metzen ◽  
Christopher A. Williams ◽  
Belinda Medlyn ◽  
...  
Keyword(s):  
Large Scale ◽  
Vegetation Index ◽  
Ecosystem Respiration ◽  
Vapour Pressure Deficit ◽  
Summer Rainfall ◽  
Mean Annual Precipitation ◽  
Surface Conductance ◽  
Mean Annual Temperature ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem–atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterised by a mean annual precipitation of 800 mm and a mean annual temperature of 18 ∘C, hot summers and mild winters, with highly variable precipitation. In the 4-year study, the ecosystem was a sink each year (−225 g C m−2 yr−1 on average, with a standard deviation of 108 g C m−2 yr−1); inter-annual variations were not related to meteorological conditions. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was significantly correlated with remotely sensed enhanced vegetation index (EVI; r2 = 0.46) and with canopy leaf area index (LAI; r2 = 0.29), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.

scholarly journals Carbon dioxide exchange of a perennial bioenergy crop cultivation on a mineral soil

2016 ◽  
Vol 13 (4) ◽  
pp. 1255-1268 ◽  
Author(s):  
Saara E. Lind ◽  
Narasinha J. Shurpali ◽  
Olli Peltola ◽  
Ivan Mammarella ◽  
Niina Hyvönen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ecosystem Respiration ◽  
Renewable Energy Sources ◽  
Mineral Soil ◽  
Vapour Pressure Deficit ◽  
Co2 Exchange ◽  
Carbon Dioxide Exchange ◽  
Bioenergy Crop ◽  
Comparison Site ◽  
Area Index

Abstract. One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinacea L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 exchange of this RCG cultivation system, and to understand the key factors controlling its CO2 exchange, the net ecosystem CO2 exchange (NEE) was measured from July 2009 until the end of 2011 using the eddy covariance (EC) method. The RCG cultivation thrived well producing yields of 6200 and 6700 kg DW ha−1 in 2010 and 2011, respectively. Gross photosynthesis (GPP) was controlled mainly by radiation from June to September. Vapour pressure deficit (VPD), air temperature or soil moisture did not limit photosynthesis during the growing season. Total ecosystem respiration (TER) increased with soil temperature, green area index and GPP. Annual NEE was −262 and −256 g C m−2 in 2010 and 2011, respectively. Throughout the study period from July 2009 until the end of 2011, cumulative NEE was −575 g C m−2. Carbon balance and its regulatory factors were compared to the published results of a comparison site on drained organic soil cultivated with RCG in the same climate. On this mineral soil site, the RCG had higher capacity to take up CO2 from the atmosphere than on the comparison site.

scholarly journals Carbon dioxide exchange of a perennial bioenergy crop cultivation on a mineral soil

2015 ◽  
Vol 12 (20) ◽  
pp. 16673-16708 ◽  
Author(s):  
S. E. Lind ◽  
N. J. Shurpali ◽  
O. Peltola ◽  
I. Mammarella ◽  
N. Hyvönen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ecosystem Respiration ◽  
Renewable Energy Sources ◽  
Mineral Soil ◽  
Vapour Pressure Deficit ◽  
Co2 Exchange ◽  
Carbon Dioxide Exchange ◽  
Published Data ◽  
Bioenergy Crop ◽  
Area Index

Abstract. One of the strategies to reduce carbon dioxide (CO2) emissions from the energy sector is to increase the use of renewable energy sources such as bioenergy crops. Bioenergy is not necessarily carbon neutral because of greenhouse gas (GHG) emissions during biomass production, field management and transportation. The present study focuses on the cultivation of reed canary grass (RCG, Phalaris arundinaceae L.), a perennial bioenergy crop, on a mineral soil. To quantify the CO2 exchange of this RCG cultivation system, and to understand the key factors controlling its CO2 exchange, the net ecosystem CO2 exchange (NEE) was measured during three years using the eddy covariance (EC) method. The RCG cultivation thrived well producing yields of 6200 and 6700 kg DW ha−1 in 2010 and 2011, respectively. Gross photosynthesis (GPP) was controlled mainly by radiation from June to September. Vapour pressure deficit (VPD), air temperature or soil moisture did not limit photosynthesis during the growing season. Total ecosystem respiration (TER) increased with soil temperature, green area index and GPP. Annual NEE was −262 and −256 g C m−2 in 2010 and 2011, respectively. Throughout the studied period, cumulative NEE was −575 g C m−2. When compared to the published data for RCG on an organic soil, the cultivation of this crop on a mineral soil had higher capacity to take up CO2 from the atmosphere.

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.

Relationships between nitrogen, acid-unhydrolyzable residue, and climate among tree foliar litters

2013 ◽  
Vol 43 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Björn Berg ◽  
Chunjiang Liu ◽  
Ryszard Laskowski ◽  
Matthew Davey
Keyword(s):  
Pinus Sylvestris ◽  
Scots Pine ◽  
Tree Species ◽  
Quercus Robur ◽  
Large Scale ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Linear Relationships ◽  
Common Oak

Using literature data, we investigated coniferous and broadleaf litter from 58 tree species using a database encompassing concentrations of N and acid-unhydrolyzable residue (AUR) (gravimetric lignin) in newly shed litter, mean annual temperature, and mean annual precipitation. Our aims were to (i) demonstrate any large-scale relationships between concentrations of N and AUR in foliar litter and (ii) determine differences in this respect among litter from Pinus and Quercus. To this end, we had collected foliar litter data for Asia and Europe, forming a climate gradient. Litter from broadleaf and coniferous trees differed significantly in concentrations of N (p < 0.0001, 9.64 versus 5.50 mg/g, respectively) and AUR (p < 0.0001, 219 versus 292 mg/g, respectively). There were highly significant positive linear relationships between concentrations of N and AUR for broadleaf (p < 0.0001) and coniferous litter (p < 0.0001). There were also significant positive relationships for AUR as a function of N concentration for the genera Pinus and Quercus but not within species. That for Scots pine (Pinus sylvestris L.) was negative and that for common oak (Quercus robur L.) not significant.

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 Influence of the Asian Monsoon on net ecosystem carbon exchange in two major plant functional types in Korea

2009 ◽  
Vol 6 (6) ◽  
pp. 10279-10309 ◽  
Author(s):  
H. Kwon ◽  
J. Kim ◽  
J. Hong
Keyword(s):  
Summer Monsoon ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Co2 Exchange ◽  
Plant Functional Types ◽  
Net Ecosystem Co2 Exchange ◽  
Area Index ◽  
Functional Types ◽  
Net Ecosystem Carbon Exchange

Abstract. Considering the feedback loops in radiation, temperature, and soil moisture with alterations in rainfall patterns, the influence of the changing monsoon on net ecosystem CO2 exchange can be critical to the estimation of carbon balance in Asia. In this paper, we examined the eddy covariance CO2 fluxes observed from 2004 to 2008 in two major plant functional types in KoFlux, i.e., the Gwangneung deciduous forest (GDK) site and the Haenam farmland (HFK) site. The objectives of the study were to (1) quantify the net ecosystem CO2 exchange (NEE), ecosystem respiration (RE), and gross primary production (GPP), (2) examine their interannual patterns, and (3) assess the mechanism for the coupling of carbon and water exchange associated with the summer monsoon. The GDK site, which had a maximum leaf area index (LAI) of ~5, was on average a relatively weak carbon sink with NEE of −84 gC m−2 y−1, RE of 1028 gC m−2 y−1, and GPP of 1113 gC m−2 y−1. Despite about 20% larger GPP (of 1321 gC m−2 y−1) in comparison with the GDK site, the HFK site (with the maximum LAI of 3 to 4) was a weaker carbon sink with NEE of −58 gC m−2 y−1 because of greater RE of 1263 gC m−2 y−1. In both sites, the annual patterns of NEE and GPP had a striking "mid-season depression" each year with two distinctive peaks of different timing and magnitude, whereas RE did not. The mid-season depression at the GDK site occurred typically from early June to late August, coinciding with the season of summer monsoon when the solar radiation decreased substantially due to frequent rainfalls and cloudiness. At the HFK site, the mid-season depression began earlier in May and continued until the end of July due to land use management (e.g., crop rotation) in addition to such disturbances as summer monsoon and typhoons. Other flux observation sites in East Asia also show a decline in radiation but with a lesser degree during the monsoon season, resulting in less pronounced depression in NEE. In our study, however, the observed depression in NEE changed the forest and farmland from a carbon sink to a source in the middle of the growing season. Consequently, the annually integrated values of NEE lies on the low end of the range reported in the literature. Such a delicate coupling between carbon and water cycles may turn these ecosystems into a stronger carbon sink with the projected trends of less frequent but more intensive rainfalls in this region.

Latest Villafranchian climate and landscape reconstructions at Pirro Nord (southern Italy)

Geology ◽  
2019 ◽  
Vol 47 (9) ◽  
pp. 829-832 ◽  
Author(s):  
Hugues-Alexandre Blain ◽  
Ana Fagoaga ◽  
Francisco Javier Ruiz-Sánchez ◽  
Josep Francesc Bisbal-Chinesta ◽  
Massimo Delfino
Keyword(s):  
Southern Italy ◽  
Numerical Data ◽  
Summer Rainfall ◽  
Distribution Patterns ◽  
Early Pleistocene ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Climate Conditions ◽  
First Occurrence ◽  
The Mean

Abstract Early Pleistocene terrestrial climate conditions in the Mediterranean region, especially between 1.3 and 1.7 Ma, are poorly understood. Here, the amphibian and reptile fossil record from 24 fissures (Cava Pirro) of the Pirro Nord karstic complex (southern Italy) is used to infer quantitative paleoclimatic and paleoenvironmental reconstructions. These numerical data indicate that the mean annual temperature may have been somewhat lower (–1.6 to –3.6 °C compared to modern temperatures) than that of today, and the mean annual precipitation slightly higher (+90 to +240 mm) than modern values. Seasonality was more pronounced, with cooler summers (–0.4 to –2.0 °C) and much colder winters (–1.2 to –6.0 °C). Rainfall distribution patterns during the year show more precipitation during the winter (+14 to +43 mm), with quantities of summer rainfall (–1.7 to +6.6 mm) being similar to modern values. The associated landscape comprised an open dry environment with scattered patches of woodland, locally along water courses or around swamps. This ecological scenario fits with early Pleistocene cold conditions, where the first occurrence of some eastern emigrants suggests a scenario of trans-Adriatic dispersal, as may have also occurred for the earliest European hominins.

Sensitivity of evapotranspiration and surface conductance to vapour pressure deficit across high latitude climatic gradients.

2021 ◽  
Author(s):  
Astrid Vatne ◽  
Lena M. Tallaksen ◽  
Norbert Pirk ◽  
Ane V. Vollsnes ◽  
Kolbjørn Engeland ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
High Latitude ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Surface Characteristic ◽  
Lower Latitude ◽  
Surface Conductance ◽  
Lower Sensitivity ◽  
Boundary Line ◽  
Area Index

&lt;p&gt;Evapotranspiration links the energy, water and carbon budgets of wetlands, a key ecosystem in high latitudes. While the evapotranspiration in high latitude wetlands is largely controlled by available energy, the surface also exerts a non-negligible control. The surface control on evapotranspiration, often represented by the surface conductance, is sensitive to environmental variables such as vapour pressure deficit (VPD). Previous studies have shown that higher surface conductance leads to higher evapotranspiration from high latitude wetlands than from high latitude forests during periods of high VDP. However, it is unclear how the surface conductance-VPD relation varies across climatic gradients. To study the sensitivity of surface conductance to increasing values of VPD, we use data from three recently established eddy covariance sites in Norway, situated along high latitude climatic gradients. The sites included are His&amp;#229;sen (680 m.a.s.l., N 61.11&amp;#176;, E 12.24&amp;#176;), Finse (1200 m.a.s.l., N 60.59&amp;#176;, E 7.53&amp;#176;) and I&amp;#353;koras (360 m.a.s.l, N 69.34&amp;#176;, E 25.29&amp;#176;). We first estimate surface conductance from the eddy covariance data, by inverting the Penman-Monteith equation. We then apply a boundary line analysis to assess the sensitivity of the surface conductance to VPD. Our preliminary results show a lower sensitivity of surface conductance to VPD on the northernmost site, compared to the two sites at lower latitude. Further work is needed to relate the observed variations in surface conductance-VPD relation to surface characteristic, and we hypothesize that the observered lower sensitivity in surface conductance is related to lower values of leaf area index. This work is a contribution to the Strategic Research Initiative &amp;#8216;Land Atmosphere Interaction in Cold Environments&amp;#8217; (LATICE) of the University of Oslo.&lt;/p&gt;

How biotic and abiotic factors affect stemflow production? Insights from both local and global scales

2020 ◽  
Author(s):  
Yafeng Zhang ◽  
Xinping Wang ◽  
Yanxia Pan ◽  
Rui Hu
Keyword(s):  
Abiotic Factors ◽  
Northern China ◽  
Boosted Regression Trees ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Abiotic Factor ◽  
Area Index ◽  
Biotic And Abiotic Factors ◽  
Vegetation Height ◽  
Caragana Korshinskii

&lt;p&gt;Stemflow production has been reported to be influenced by a suite of biotic and abiotic factors, and those factors would be quite different considering local and global scales. Although the number of published stemflow studies showed a steady increasing trend in recent years, the relative contributions of biotic and abiotic factors to stemflow production were still largely unclear due to the large number of influencing factors and the complex interactions among those factors. Here we present stemflow results conducted from both from local scale and global scale: (1) stemflow of nine xerophytic shrubs of Caragana korshinskii were measured in nearly nine growing seasons from 2010 to 2018 within a desert area of northern China, accompanying with observing on six biotic variables (shrub morphological attributes) and ten abiotic variables (meteorological conditions); (2) a global synthesis of stemflow production results (stemflow percentage was reported) derived from Web of Science for more than 200 peer-reviewed papers published in the last 50 years (1970-2019), and ten most reported biotic factors (vegetation life form, phenology, leaf form, bark form, community density, community age, vegetation height, diameter at breast height, leaf area index, stemflow measuring scale) and four abiotic factors (climate types, mean annual precipitation, elevation, mean annual temperature) were considered. We performed a machine learning method (boosted regression trees) to evaluate the relative contribution of each biotic and abiotic factor to stemflow percentage, and partial dependence plots were presented to visualize the effects of individual explanatory variables on stemflow percentage, respectively.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document