scholarly journals Groundwater‐River Water Exchange Enhances Growing Season Evapotranspiration and Carbon Uptake in a Semiarid Riparian Ecosystem

2019 ◽  
Vol 124 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Justine E. C. Missik ◽  
Heping Liu ◽  
Zhongming Gao ◽  
Maoyi Huang ◽  
Xingyuan Chen ◽  
...  
Keyword(s):  
River Water ◽  
Water Exchange ◽  
Growing Season ◽  
Carbon Uptake ◽  
Riparian Ecosystem

The relative importance of environmental factors on the interannual variability of carbon fluxes in the boreal forest

2020 ◽  
Author(s):  
Mariam El-Amine ◽  
Alexandre Roy ◽  
Pierre Legendre ◽  
Oliver Sonnentag
Keyword(s):  
Environmental Factors ◽  
Boreal Forest ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Carbon Sink ◽  
Growing Season ◽  
Carbon Uptake ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Environmental Controls

<p>As climate change will cause a more pronounced rise of air temperature in northern high latitudes than in other parts of the world, it is expected that the strength of the boreal forest carbon sink will be altered. To better understand and quantify these changes, we studied the influence of different environmental controls (e.g., air and soil temperatures, soil water content, photosynthetically active radiation, normalized difference vegetation index) on the timing of the start and end of the boreal forest growing season and the net carbon uptake period in Canada. The influence of these factors on the growing season carbon exchanges between the atmosphere and the boreal forest were also evaluated. There is a need to improve the understanding of the role of the length of the growing season and the net carbon uptake period on the strength of the boreal forest carbon sink, as an extension of these periods might not necessarily result in a stronger carbon sink if other environmental factors are not optimal for carbon sequestration or enhance respiration.</p><p>Here, we used 31 site-years of observation over three Canadian boreal forest stands: Eastern, Northern and Southern Old Black Spruce in Québec, Manitoba and Saskatchewan, respectively. Redundancy analyses were used to highlight the environmental controls that correlate the most with the annual net ecosystem productivity and the start and end of the growing season and the net carbon uptake period. Preliminary results show that the timing at which the air temperature becomes positive correlates the most strongly with the start of the net carbon uptake period (r = 0.70, p < 0.001) and the start of the growing season (r = 0.55, p < 0.01). Although the increase of the normalized difference vegetation index also correlates with the start of these periods, a thorough examination of this result shows that the latter happens well before the former. No dependency between any environmental control and the end of the net carbon uptake period was identified. Also, the annual net ecosystem productivity is highly correlated with the length of the net carbon uptake period (r = 0.54, p < 0.01). Other environmental controls such as annual precipitations, the mean annual soil temperature or the maximum yearly normalized difference vegetation index have a smaller impact on the annual net ecosystem productivity. By extending the dataset to include forest stands that represent a wider climate and permafrost variability, we will examine the generalizability of these results.</p>

scholarly journals Eco-hydrological effects of stream-aquifer water interaction: A case study of the Heihe River Basin, northwestern China

2016 ◽  
Author(s):  
Yujin Zeng ◽  
Zhenghui Xie ◽  
Yan Yu ◽  
Shuang Liu ◽  
Linying Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Level ◽  
River Water ◽  
River Basin ◽  
Water Table ◽  
Riparian Vegetation ◽  
Stream Water ◽  
Growing Season ◽  
Heihe River Basin ◽  
Heihe River

Abstract. A scheme describing the process of stream-aquifer interaction was incorporated into the land model CLM4.5 to investigate the effects of stream water conveyance over riparian banks on ecological and hydrological processes. Two groups of simulations for five typical river cross-sections in the middle reaches of the arid zone Heihe River Basin were conducted. The simulated riparian ground water table at a propagation distance of less than 1 km followed the intra-annual flu ctuation of the river water level, and the correlation was excellent (R2 = 0.9) between the river water level and the groundwater table at the distance 60 m from the river. The correlation rapidly decreased as distance increased. In response to the variability of the water table, soil moisture at deep layers also followed the variation of river water level all year, while soil moisture at the surface layer was more sensitive to the river water level in the drought season than in the wet season. With increased soil moisture, the average gross primary productivity and respiration of riparian vegetation within 300 m from the river at a typical section of the river increased by approximately 0.03 mg C m−2 s−1 and 0.02 mg C m −2 s−1, respectively, in the growing season. Consequently, the net ecosystem exchange increased by approximately 0.01 mg C m−2 s−1, and the evapotranspiration increased by approximately 3 mm d−1. Furthermore, the length of the growing season of riparian vegetation also increased by 2–3 months due to the sustaining water recharge from the river.

scholarly journals Seasonal courses of photosynthetic parameters in sun- and shade-acclimated spruce shoots

Beskydy ◽  
2017 ◽  
Vol 10 (1-2) ◽  
pp. 49-56 ◽  
Author(s):  
Otmar Urban ◽  
Petr Holub ◽  
Karel Klem
Keyword(s):  
Photosynthetic Capacity ◽  
Dark Respiration ◽  
Carbon Assimilation ◽  
Growing Season ◽  
Early Spring ◽  
Total Carbon ◽  
Carbon Gain ◽  
Carbon Uptake ◽  
Photosynthetic Parameters ◽  
Sun And Shade

Exponential attenuation of light intensity passing through forest canopies leads to the formation of sun- and shade-acclimated leaves contributing to overall canopy carbon gain. Using a gas-exchange technique, seasonal changes in photosynthetic parameters were investigated in situ to test the hypothesis that the relative contributions of sun- and shade-acclimated Norway spruce shoots to total carbon gain vary during the growing season and that the contribution of sun-acclimated shoots to total carbon uptake may be reduced during the hot and dry summer season. In agreement with the tested hypothesis, we found reduced photosynthetic capacity as well as reduced light-use efficiency for carbon assimilation in sun-acclimated shoots during summer months while these remained almost unchanged in shade-acclimated shoots. Reduction of photosynthetic capacity was primarily associated with reduced stomatal conductance. On the other hand, seasonal courses of mitochondrial dark respiration, quantum efficiency of photosynthetic reactions, and compensation irradiance were primarily driven by changes in temperature. Accordingly, the photosynthetic characteristics of sun- and shade-acclimated shoots tended to converge in early spring and late autumn when temperature was low. Such seasonal dynamics result in an increased contribution of shade-acclimated shoots to total carbon uptake at the beginning and end of the growing season as well as during hot and dry summer periods.

scholarly journals Effects of nitrogen fertilization on the understorey carbon balance over the growing season in a boreal Pine forest

2013 ◽  
Vol 10 (8) ◽  
pp. 14093-14113
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Nitrogen Availability ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Carbon Uptake ◽  
Sink Strength ◽  
Understorey Vegetation ◽  
Ecosystem Carbon ◽  
Photosynthetic Carbon

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate. We quantified the effects of nitrogen availability on carbon fluxes from a relatively understudied component of these forests – understorey vegetation – at three intervals over the summer growing period in a northern Swedish Scots Pine stand. Nitrogen addition altered both photosynthetic carbon uptake and respiratory release, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net ecosystem carbon uptake only in the late growing season. We find evidence for species-specific control of understorey carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of photosynthetic carbon uptake with data on plant carbon dioxide release from the study site, indicate that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in understorey and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

Monitoring Agricultural Drainage Ditches and the Receiving Water (Nicomekl River, Surrey, B.C.) for Toxicity to Ceriodaphnia dubia and Probable Cause Due to Organophosphate Contamination

1999 ◽  
Vol 34 (3) ◽  
pp. 423-454 ◽  
Author(s):  
M.J. McLeay ◽  
K.J. Hall
Keyword(s):  
River Water ◽  
Water Samples ◽  
Toxicity Test ◽  
Test Organism ◽  
Growing Season ◽  
Ceriodaphnia Dubia ◽  
Piperonyl Butoxide ◽  
Drainage Ditches ◽  
River Water Samples ◽  
Organophosphate Insecticides

Abstract The use of organophosphate insecticides on commercial vegetable and blueberry farmlands bordering the Nicomekl River, Surrey, B.C., creates the potential for toxic effects on the biota within the drainage ditches and the river itself. To investigate the frequency and magnitude of the toxicity of drainage ditch water and the river water in the vicinity of ditch discharge points, together with the probable cause, water samples were collected from six drainage ditches, and four river locations, at 3-week intervals between June and November 1997. For each of the water samples collected, chronic (7 ± 1 day) survival and reproduction of the cladoceran test organism Ceriodaphnia dubia were compared to that of Nicomekl River headland waters beyond the influence of commercial growing operations. Portions of samples proving to be lethally toxic to the toxicity-test organism were analyzed for organophosphate insecticides (OPs) and subjected to treatment with piperonyl butoxide to ascertain if OPs were the likely contributing cause of the toxicity. Throughout the 6-month monitoring period, a total of 50 ditch water samples and 35 Nicomekl river water samples were collected. None of the river water samples tested produced statistically significant mortality. Two (4%) of the ditch water samples were lethally toxic, with 6- and 7-day median lethal concentrations (LC50s) of 39.9 and 36.5%, respectively. Seven (14%) of the ditch water samples and three (9%) of the river water samples inhibited C. dubia reproduction. A biological toxicity identification evaluation using piperonyl butoxide determined that the toxicant(s) in each of the two ditch water samples which proved lethal to C. dubia were likely metabolically active OP insecti-cide(s). Later chemical analyses on stored portions of the samples revealed trace quantities of chlorpyrifos and/or diazinon. These and other non-measured OPs are believed to have been responsible for the observed lethality. The cause of the inhibited reproduction is for the most part unknown. Providing the 1997 growing season is a typical growing season in terms of OP insecticide use and rainfall, the C. dubia toxicity test results suggest that during the growing season the Nicomekl River and its drainage ditches may periodically be contaminated with OP insecticides at concentrations high enough to sublethally or lethally impact sensitive ditch and river invertebrate fish-food organisms.

scholarly journals Seasonality of soil water exchange in the soybean growing season in southern Brazil

2015 ◽  
Vol 72 (2) ◽  
pp. 103-113 ◽  
Author(s):  
Virnei Silva Moreira ◽  
Débora R. Roberti ◽  
Jean Paolo Minella ◽  
Luis Gustavo G de Gonçalves ◽  
Luiz Antônio Candido ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Exchange ◽  
Growing Season ◽  
Southern Brazil

scholarly journals The Stable Isotopic Composition of Different Water Bodies at the Soil–Plant–Atmosphere Continuum (SPAC) of the Western Loess Plateau, China

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1742
Author(s):  
Che ◽  
Zhang ◽  
Argiriou ◽  
Wang ◽  
Du ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
River Water ◽  
Soil Layer ◽  
Growing Season ◽  
Water Bodies ◽  
Lanzhou City ◽  
Shallow Soil ◽  
Water Plant ◽  
Stable Isotopic

Understanding the isotopic composition and interrelations of different water bodies at the soil–plant–atmosphere continuum (SPAC) is crucial to reveal the processes and mechanisms of regional water cycles. Rainfall, river water, plant, and soil samples from Lanzhou City, China, were collected from April to October 2016. The hydrogen (δ2H) and oxygen (δ18O) of the local precipitation, river water, soil water, plant xylem water, and leaf water were determined. We found that trees mainly uptake the middle (30–60 cm) and deep (60–100 cm) layer soil water during the growing season, and the shrubs mainly uptake the middle soil water. All herbs uptake the shallow soil water (0–30 cm) during the growing season. The δ18O of shallow soil water was found to be isotopic-enriched because of evaporation and exhibited a decline from the shallow soil layer towards the deeper layer. The variation of δ18O and soil water content (SWC) was remarkable in shallow soil, which was mainly due to evaporation and precipitation infiltration, while water in the middle and deep layer was less affected by these phenomena.

scholarly journals Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

2011 ◽  
Vol 8 (6) ◽  
pp. 1667-1678 ◽  
Author(s):  
W.-J. Zhang ◽  
H.-M. Wang ◽  
F.-T. Yang ◽  
Y.-H. Yi ◽  
X.-F. Wen ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Air Temperature ◽  
Growing Season ◽  
Carbon Uptake ◽  
Summer Drought ◽  
Eddy Flux ◽  
Season Length ◽  
Growing Season Length ◽  
Coniferous Plantation ◽  
The Impact

Abstract. The impact of air temperature in early growing season on the carbon sequestration of a subtropical coniferous plantation was discussed through analyzing the eddy flux observations at Qianyanzhou (QYZ) site in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5 °C) in 2005 and 2008, and a severe summer drought in 2003. Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2=0.970, p<0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-month temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

scholarly journals Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere

2012 ◽  
Vol 26 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. Barichivich ◽  
K. R. Briffa ◽  
T. J. Osborn ◽  
T. M. Melvin ◽  
J. Caesar
Keyword(s):  
Northern Hemisphere ◽  
Growing Season ◽  
Carbon Uptake
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