scholarly journals Temporal and microtopographical variations in greenhouse gas fluxes from riparian forest soils along headwater streams

2021 ◽  
Author(s):  
Teresa K. Silverthorn ◽  
John S. Richardson
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Greenhouse Gas ◽  
Riparian Zone ◽  
Headwater Streams ◽  
Riparian Forest ◽  
Ecosystem Functions ◽  
Riparian Zones ◽  
Gas Fluxes ◽  
Ghg Fluxes

Abstract Riparian zones of headwater streams have valuable ecosystem functions and are prevalent across many landscapes. Nevertheless, studies of greenhouse gas (GHG; CO 2 , CH 4 , N 2 O) fluxes from these unique ecosystems, with fluctuating water tables and high soil organic matter, remain limited. Our objectives were to (1) to quantify the effects of local riparian groundwater conditions on soil GHG flux rates, namely to determine if groundwater discharge (DIS) areas in the riparian zone would have higher soil moisture than adjacent non-discharge (ND) areas in the riparian zone, impacting GHG fluxes; and (2) to examine the relationship between GHG fluxes, soil moisture, soil temperature, and groundwater depth. We measured gas fluxes in situ alongside two relatively undisturbed headwater streams over one year, using closed static chambers and gas chromatography. We found that, although not significant, DIS areas had on average lower CH 4 uptake and lower CO 2 emissions than ND areas. We further found that soil temperature explained 30.0% and 26.2% of variation in CO 2 and N 2 O fluxes, respectively, and soil moisture explained 9.8% of variation in CH 4 fluxes. Our results provide information on the magnitude and drivers of GHG fluxes in riparian zones to help inform GHG budgets and forest management.

scholarly journals Soil greenhouse gas fluxes from different tree species on Taihang Mountain, North China

2014 ◽  
Vol 11 (6) ◽  
pp. 1649-1666 ◽  
Author(s):  
X. P. Liu ◽  
W. J. Zhang ◽  
C. S. Hu ◽  
X. G. Tang
Keyword(s):  
Soil Moisture ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Temperature ◽  
Soil Ph ◽  
Tree Species ◽  
Soil Bulk Density ◽  
Total N ◽  
Gas Fluxes ◽  
Greenhouse Gas Fluxes

Abstract. The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N2O. Tree species had a significant effect on CO2 and N2O releases but not on CH4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.

scholarly journals Does soil moisture overrule temperature dependency of soil respiration in Mediterranean riparian forests?

2014 ◽  
Vol 11 (6) ◽  
pp. 7991-8022 ◽  
Author(s):  
C.-T. Chang ◽  
S. Sabaté ◽  
D. Sperlich ◽  
S. Poblador ◽  
F. Sabater ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Groundwater Level ◽  
Tree Species ◽  
Riparian Forest ◽  
Co2 Flux ◽  
Control Factor ◽  
Primary Control ◽  
Heterotrophic Soil Respiration

Abstract. Soil respiration (SR) is a major component of ecosystem's carbon cycle and represents the second largest CO2 flux of the terrestrial biosphere. Soil temperature is considered to be the primary control on SR whereas soil moisture as the secondary control factor. However, soil moisture can become the dominant control on SR in very wet or dry conditions. Determining the trigger that switches-on soil moisture as the primary control factor of SR will provide a deeper understanding on how SR changes under projected future increased droughts. Specific objectives of this study were (1) to investigate the seasonal variations and the relationship between SR and both soil temperature and moisture in a Mediterranean riparian forest along a groundwater level gradient; (2) to determine soil moisture thresholds at which SR is rather controlled by soil moisture than by temperature; (3) to compare SR responses under different tree species present in a Mediterranean riparian forest (Alnus, glutinosa, Populus nigra and Fraxinus excelsior). Results showed that the heterotrophic soil respiration rate, groundwater level and 30 cm integral soil moisture (SM30) decreased significantly from riverside to uphill and showed a pronounced seasonality. SR rates showed significant differences among tree species, with higher SR for P. nigra and lower SR for A. glutinosa. The lower threshold of soil moisture was 20 and 17% for heterotrophic and total SR respectively. Daily mean SR rate was positively correlated with soil temperature when soil moisture exceeded the threshold, with Q10 values ranging from 1.19 to 2.14; nevertheless, SR became decoupled from soil temperature when soil moisture dropped below these thresholds.

scholarly journals Decadal variability of soil CO<sub>2</sub>, NO, N<sub>2</sub>O, and CH<sub>4</sub> fluxes at the Höglwald Forest, Germany

2012 ◽  
Vol 9 (5) ◽  
pp. 1741-1763 ◽  
Author(s):  
G. J. Luo ◽  
N. Brüggemann ◽  
B. Wolf ◽  
R. Gasche ◽  
R. Grote ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Trace Gases ◽  
Trace Gas ◽  
High Temporal Resolution ◽  
N2o Production ◽  
Field Station ◽  
Freeze Thaw ◽  
Gas Fluxes ◽  
Trace Gas Fluxes

Abstract. Besides agricultural soils, temperate forest soils have been identified as significant sources of or sinks for important atmospheric trace gases (N2O, NO, CH4, and CO2). Although the number of studies for this ecosystem type increased more than tenfold during the last decade, studies covering an entire year and spanning more than 1–2 years remained scarce. This study reports the results of continuous measurements of soil-atmosphere C- and N-gas exchange with high temporal resolution carried out since 1994 at the Höglwald Forest spruce site, an experimental field station in Southern Germany. Annual soil N2O, NO and CO2 emissions and CH4 uptake (1994–2010) varied in a range of 0.2–3.0 kg N2O-N ha−1yr−1, 6.4–11.4 kg NO-N ha−1yr−1, 7.0–9.2 t CO2-C ha−1yr−1, and 0.9–3.5 kg CH4-C ha−1yr−1, respectively. The observed high fluxes of N-trace gases are most likely a consequence of high rates of atmospheric nitrogen deposition (>20 kg N ha−1yr−1) of NH3 and NOx to our site. For N2O, cumulative annual emissions were ≥ 0.8 kg N2O-N ha−1yr−1 in years with freeze-thaw events (5 out 14 of years). This shows that long-term, multi-year measurements are needed to obtain reliable estimates of N2O fluxes for a given ecosystem. Cumulative values of soil respiratory CO2 fluxes tended to be highest in years with prolonged freezing periods, i.e. years with below average annual mean soil temperatures and high N2O emissions (e.g. the years 1996 and 2006). Furthermore, based on our unique database on trace gas fluxes we analyzed if soil temperature, soil moisture measurements can be used to approximate trace gas fluxes at daily, weekly, monthly, or annual scale. Our analysis shows that simple-to-measure environmental drivers such as soil temperature or soil moisture are suitable to approximate fluxes of NO and CO2 at weekly and monthly resolution reasonably well (accounting for up to 59 % of the variance). However, for CH4 we so far failed to find meaningful correlations, and also for N2O the predictive power is rather low. This is most likely due to the complexity of involved processes and counteracting effects of soil moisture and temperature, specifically with regard to N2O production and consumption by denitrification and microbial community dynamics. At monthly scale, including information on gross primary production (CO2, NO), and N deposition (N2O), increased significantly the explanatory power of the obtained empirical regressions (CO2: r2 =0.8; NO: r2 = 0.67; N2O, all data: r2 = 0.5; N2O, with exclusion of freeze-thaw periods: r2 = 0.65).

scholarly journals Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

2012 ◽  
Vol 9 (8) ◽  
pp. 10057-10085
Author(s):  
U. Skiba ◽  
S. K. Jones ◽  
J. Drewer ◽  
C. Helfter ◽  
M. Anderson ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Net Ecosystem Exchange ◽  
Ground Vegetation ◽  
Co2 Uptake ◽  
Gas Fluxes ◽  
Greenhouse Gas Fluxes ◽  
Temperature Radiation ◽  
Ch4 And N2o ◽  
Ghg Fluxes ◽  
Grazed Grassland

Abstract. Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep grazed drained moorland and intensively sheep grazed fertilised grassland in SE Scotland were compared over 4 yr (2007–2010). Nitrous oxide and CH4 fluxes were measured by static chambers, respiration from soil including ground vegetation by a flow through chamber and the net ecosystem exchange of CO2 by eddy covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO2, emissions of N2O from the grazed grassland (384 g CO2eq m−2 yr−1) and emissions of CH4 from ruminant fermentation (147 g CO2eq m−2 yr−1). Methane emissions from the moorland were small (6.7 g CO2eq m−2 yr−1). Net ecosystem exchange of CO2 and respiration were much larger on the productive fertilised grassland (−1624 and +7157 g CO2eq m−2 yr−1, respectively) than the seminatural moorland (−338 and +2554 g CO2eq m−2 yr−1, respectively). Large CH4 and N2O losses from the grazed grassland counteracted the CO2 uptake by 35%, whereas the small N2O and CH4 emissions from the moorland did only impact the NEE by 2%.The 4 yr average GHG budget for the grazed grassland was 1006 g CO2eq m−2 yr−1 and 331 g CO2eq m−2 yr−1 for the moorland.

scholarly journals Do wider riparian zones alter benthic macroinvertebrate assemblages’ diversity and taxonomic composition in neotropical headwater streams?

2021 ◽  
Vol 33 ◽  
Author(s):  
Marden S. Linares ◽  
Livia B. dos Santos ◽  
Marcos Callisto ◽  
Jean C. Santos
Keyword(s):  
Riparian Zone ◽  
Headwater Streams ◽  
Taxonomic Composition ◽  
Functional Structure ◽  
Riparian Zones ◽  
Benthic Macroinvertebrate ◽  
Freshwater Ecosystem ◽  
Benthic Assemblages ◽  
Macroinvertebrate Assemblages ◽  
Zone Width

Abstract: Aim The maintenance and condition of riparian vegetation are important factors for conserving headwater streams and their species diversity. Thus, variations in the width of a riparian zone can have dramatic effects in the structure and functioning of the adjacent freshwater ecosystem. In this study, we aimed to determine if increased riparian zone width changed the benthic assemblages’ structure (diversity, taxonomic and functional composition) in headwater streams. Methods We tested two predictions: (1) increased riparian zone width will change the diversity and taxonomic composition of benthic macroinvertebrate assemblages because narrow riparian zones do not buffer the anthropogenic impacts from the surrounding landscape; (2) wider riparian zones will change benthic macroinvertebrate assemblages’ functional structure, due to changes to energetic input and quality. To test the first prediction, we assessed the benthic macroinvertebrate assemblages’ taxonomic composition, richness and Shannon-Wiener diversity index. To test the second prediction, we assessed functional feeding groups (FFG) and metrics based on their proportion. Results Our results showed that our first prediction was not corroborated, because taxonomic structure and diversity did not show significant variation with increased riparian zone width. Our second prediction was partially corroborated, because there were significant alterations in the functional structure of benthic macroinvertebrate assemblages between the narrowest riparian zone width (30 m) and the others two (50 and 100 m). Conclusions Our results suggest that, contrary to the Brazilian Federal Law 12651/2012, 30-m wide riparian zones are insufficient to protect headwater stream ecosystem functioning.

scholarly journals Direct and Indirect Effects of Soil Fauna, Fungi and Plants on Greenhouse Gas Fluxes

2021 ◽  
pp. 151-176
Author(s):  
M. Zaman ◽  
K. Kleineidam ◽  
L. Bakken ◽  
J. Berendt ◽  
C. Bracken ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Indirect Effects ◽  
Biological Properties ◽  
Plant Residues ◽  
Direct And Indirect Effects ◽  
Gas Fluxes ◽  
Wide Range ◽  
Greenhouse Gas Fluxes ◽  
Metabolic Activities ◽  
Ghg Fluxes

AbstractSoils harbour diverse soil faunaand a wide range of soil microorganisms. These fauna and microorganisms directly contribute to soil greenhouse gas (GHG) fluxes via their respiratory and metabolic activities and indirectly by changing the physical, chemical and biological properties of soils through bioturbation, fragmentation and redistribution of plant residues, defecation, soil aggregate formation, herbivory, and grazing on microorganisms and fungi. Based on recent results, the methods and results found in relation to fauna as well as from fungi and plants are presented. The approaches are outlined, and the significance of these hitherto ignored fluxes is discussed.

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