scholarly journals Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

2015 ◽  
Vol 120 (5) ◽  
pp. 819-831 ◽  
Author(s):  
J. P. Goodrich ◽  
D. I. Campbell ◽  
N. T. Roulet ◽  
M. J. Clearwater ◽  
L. A. Schipper
Keyword(s):  
Southern Hemisphere ◽  
Water Table ◽  
Temporal Variability ◽  
Methane Flux ◽  
Raised Bog

scholarly journals Methane flux from drained northern peatlands: Effect of a persistent water table lowering on flux

1993 ◽  
Vol 7 (4) ◽  
pp. 749-769 ◽  
Author(s):  
Nigel T. Roulet ◽  
R. Ash ◽  
W. Quinton ◽  
Tim Moore
Keyword(s):  
Water Table ◽  
Methane Flux ◽  
Northern Peatlands

scholarly journals Methane flux: Water table relations in northern wetlands

1993 ◽  
Vol 20 (7) ◽  
pp. 587-590 ◽  
Author(s):  
T. R. Moore ◽  
N. T. Roulet
Keyword(s):  
Water Table ◽  
Methane Flux

scholarly journals Controls and characteristics of variability in soil moisture and groundwater in a headwater catchment

2014 ◽  
Vol 11 (8) ◽  
pp. 9475-9517
Author(s):  
H. K. McMillan ◽  
M. S. Srinivasan
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Water Table ◽  
Temporal Variability ◽  
Extreme Values ◽  
Stream Water ◽  
Spatial And Temporal Variability ◽  
Multiple Time ◽  
Strong Impact ◽  
Strong Control

Abstract. This paper presents experimental results from a new headwater research catchment in New Zealand. We made distributed measurements of streamflow, soil moisture and groundwater levels, sampling across a range of aspects, hillslope positions, distances from stream and depths. Our aim was to assess the controls, types and implications of spatial and temporal variability in surface and groundwaters. We found that temporal variability is strongly controlled by the seasonal cycle, for both soil moisture and water table, and for both the mean and extremes of the distributions. The standard deviation of both soil moisture and groundwater values calculated per timestep is larger in winter than in summer, and standard deviations typically peak during rainfall events due to partial saturation of the catchment. Controls on the spatial variability differed between the water stores. Aspect had a strong control on groundwater but not on soil moisture, distance from stream controlled both soil moisture and groundwater. The depth of the soil moisture sensor had little impact in terms of mean water content, but a strong impact on the extreme values, i.e. saturation. Co-measurement of soil moisture and water table level variability allowed us to identify variability components that differed between these water stores e.g. patterns of strong response in soil water content were not the same for groundwater level, and those that were consistent e.g. vertical infiltration of summer rainfall through upper and lower soil depths, or rising near-stream water tables through shallow wells to lower soil depths. Signatures of variability were observed in the streamflow series, showing that understanding variability is important for hydrological prediction. Total catchment variability is composed of multiple variability sources. The dominant variability type changes with catchment wetness conditions according to which water stores are active, and in particular those which are close to a threshold such as field capacity or saturation. Our results suggest that the integrative processes that create emergent catchment behaviour should be understood as the sum of these multiple, time varying components.

scholarly journals Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

2016 ◽  
Author(s):  
Sung Ching Lee ◽  
Andreas Christen ◽  
Andy T. Black ◽  
Mark S. Johnson ◽  
Rachhpal S. Jassal ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Water Table ◽  
Time Horizon ◽  
Ecosystem Respiration ◽  
High Water ◽  
Co2 Uptake ◽  
Raised Bog ◽  
Peat Mining ◽  
Ch4 Emissions ◽  
Carbon Dioxide Co2

Abstract. Many peatlands have been drained and harvested for peat mining, which has turned them from carbon (C) sinks into C emitters. Rewetting of disturbed peatlands facilitates their ecological recovery, and may help them revert to carbon dioxide (CO2) sinks. However, rewetting may also cause substantial emissions of the more potent greenhouse gas (GHG) methane (CH4). Our knowledge on the exchange of CO2 and CH4 following rewetting during restoration of disturbed peatlands is currently limited. This study quantifies annual fluxes of CO2 and CH4 in a disturbed and rewetted area located in the Burns Bog Ecological Conservancy Area in Delta, BC, Canada. Burns Bog is recognized as the largest raised bog ecosystem on North America's West Coast. Burns Bog was substantially reduced in size and degraded by peat mining and agriculture. Since 2005, the bog has been declared a conservancy area, with restoration efforts focusing on rewetting disturbed ecosystems to recover Sphagnum and suppress fires. Using the eddy-covariance (EC) technique, we measured year-round (16th June 2015 to 15th June 2016) turbulent fluxes of CO2 and CH4 from a tower platform in an area rewetted for the last 8 years. The study area, dominated by sedges and Sphagnum, experienced a varying water table position that ranged between 7.7 (inundation) and −26.5 cm from the surface during the study year. The annual CO2 budget of the rewetted area was −179 g CO2-C m−2 year−1 (CO2 sink) and the annual CH4 budget was 16 g CH4-C m−2 year−1 (CH4 source). Gross ecosystem productivity (GEP) exceeded ecosystem respiration (Re) during summer months (June–August), causing a net CO2 uptake. In summer, high CH4 emissions (121 mg CH4-C m−2 day−1) were measured. In winter (December–February), while roughly equal magnitudes of GEP and Re made the study area CO2 neutral, very low CH4 emissions (9 mg CH4-C m−2 day−1) were observed. The key environmental factors controlling the seasonality of these exchanges were downwelling photosynthetically active radiation and 5-cm soil temperature. It appears that the high water table caused by ditch blocking which suppresses Re. With low temperatures in winter, CH4 emission was more suppressed than Re. Annual net GHG flux from CO2 and CH4 expressed in terms of CO2 equivalents (CO2e) during the study period totaled to −55 g CO2e m−2 year−1 (net CO2e sink) and 1147 g CO2e m−2 year−1 (net CO2e source) by using 100-year and 20-year global warming potential values, respectively. Consequently, the ecosystem was almost CO2e neutral during the study period expressed on a 100-year time horizon but was a significant CO2e source on a 20-year time horizon.

scholarly journals Annual greenhouse gas budget for a bog ecosystem undergoing restoration by rewetting

2017 ◽  
Vol 14 (11) ◽  
pp. 2799-2814 ◽  
Author(s):  
Sung-Ching Lee ◽  
Andreas Christen ◽  
Andrew T. Black ◽  
Mark S. Johnson ◽  
Rachhpal S. Jassal ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Water Table ◽  
Time Horizon ◽  
Ecosystem Respiration ◽  
High Water ◽  
Co2 Uptake ◽  
Raised Bog ◽  
Peat Mining ◽  
Ch4 Emissions ◽  
Carbon Dioxide Co2

Abstract. Many peatlands have been drained and harvested for peat mining, agriculture, and other purposes, which has turned them from carbon (C) sinks into C emitters. Rewetting of disturbed peatlands facilitates their ecological recovery and may help them revert to carbon dioxide (CO2) sinks. However, rewetting may also cause substantial emissions of the more potent greenhouse gas (GHG) methane (CH4). Our knowledge of the exchange of CO2 and CH4 following rewetting during restoration of disturbed peatlands is currently limited. This study quantifies annual fluxes of CO2 and CH4 in a disturbed and rewetted area located in the Burns Bog Ecological Conservancy Area in Delta, BC, Canada. Burns Bog is recognized as the largest raised bog ecosystem on North America's west coast. Burns Bog was substantially reduced in size and degraded by peat mining and agriculture. Since 2005, the bog has been declared a conservancy area, with restoration efforts focusing on rewetting disturbed ecosystems to recover Sphagnum and suppress fires. Using the eddy covariance (EC) technique, we measured year-round (16 June 2015 to 15 June 2016) turbulent fluxes of CO2 and CH4 from a tower platform in an area rewetted for the last 8 years. The study area, dominated by sedges and Sphagnum, experienced a varying water table position that ranged between 7.7 (inundation) and −26.5 cm from the surface during the study year. The annual CO2 budget of the rewetted area was −179 ± 26.2 g CO2–C m−2 yr−1 (CO2 sink) and the annual CH4 budget was 17 ± 1.0 g CH4–C m−2 yr−1 (CH4 source). Gross ecosystem productivity (GEP) exceeded ecosystem respiration (Re) during summer months (June–August), causing a net CO2 uptake. In summer, high CH4 emissions (121 mg CH4–C m−2 day−1) were measured. In winter (December–February), while roughly equal magnitudes of GEP and Re made the study area CO2 neutral, very low CH4 emissions (9 mg CH4–C m−2 day−1) were observed. The key environmental factors controlling the seasonality of these exchanges were downwelling photosynthetically active radiation and 5 cm soil temperature. It appears that the high water table caused by ditch blocking suppressed Re. With low temperatures in winter, CH4 emissions were more suppressed than Re. Annual net GHG flux from CO2 and CH4 expressed in terms of CO2 equivalents (CO2 eq.) during the study period totalled −22 ± 103.1 g CO2 eq. m−2 yr−1 (net CO2 eq. sink) and 1248 ± 147.6 g CO2 eq. m−2 yr−1 (net CO2 eq. source) by using 100- and 20-year global warming potential values, respectively. Consequently, the ecosystem was almost CO2 eq. neutral during the study period expressed on a 100-year time horizon but was a significant CO2 eq. source on a 20-year time horizon.

EFFECT OF DRAIN‐BLOCKING AND METEOROLOGICAL FACTORS ON GROUND WATER TABLE FLUCTUATIONS IN KAMANOS MIRE/GRIOVIŲ BLOKAVIMO BEI METEOROLOGINIŲ FAKTORIŲ ĮTAKA KAMANŲ PELKĖS GRUNTINIŲ VANDENŲ SLŪGSOJIMO LYGIO SVYRAVIMAMS/ ВЛИЯНИЕ ИЗМЕНЕНИЯ КЛИМАТА И УНИЧТОЖЕНИЯ КАНАВ НА ГИДРОЛОГИЧЕСКИЙ РЕЖИМ БОЛОТА КАМАНОС

2008 ◽  
Vol 16 (4) ◽  
pp. 168-177 ◽  
Author(s):  
Juozas Ruseckas ◽  
Vaidotas Grigaliūnas
Keyword(s):  
Water Table ◽  
Meteorological Factors ◽  
Growth Period ◽  
Water Table Depth ◽  
Ground Vegetation ◽  
Eriophorum Vaginatum ◽  
Drainage Ditches ◽  
Raised Bog ◽  
Pine Trees ◽  
Similar Depth

The study was carried out in a raised bog located in the Kamanos state reserve in northwestern Lithuania (56°16'N, 22°39'W). The area of the raised bog is 1722 ha. To assess the effect of meteorological factors and damming of drainage ditches on the water regime of the Kamanos mire, we have analysed the water table depth fluctuations over the last 22 years in the northern part of the mire, which was drained out in 1907, and the drainage ditch was dammed in 1999. The control plots were established in the central part of the raised bog without draining activities, where Eriophorum va‐ginatum‐Sphagnum spp. communities prevail in the ground vegetation and small Scots pine trees may also be found. The results showed that, in both natural and damaged‐by‐drainage sites of the raised bog, the air moisture deficiency and the amount of precipitation had a significant effect on the fluctuation of the water table depth during the growth period (R = 0.416 - 0.761 p < 0.05). In comparison with the control plots, in 7 years after establishing dams in a 0.9–1.2 m deep ditch, the groundwater table increased by 9.8 to 12.2 cm in the area up to 980 m apart from the ditch. After damming the ditches in the extensively and intensively drained parts of the raised bog, the levelling out of the water table to a similar depth as in the control plots, occurred within 4 years and is forecasted to occur within 12 years, respectively. The water table of the drained sites of the raised bog was more sensitive to increasing annual temperatures than the water table in the undrained sites of the raised bog. Santrauka Tyrimai buvo atlikti Kamanų valstybinio gamtinio rezervato aukštapelkėje (56º16´N, 22º39´W), kuri yra šiaurės vakarų Lietuvoje. Aukštapelkės plotas – 1722 ha. Tam, kad būtų įvertinta meteorologinių faktorių bei griovių tvenkimo įtaka Kamanų pelkės hidrologijai, buvo išanalizuotos gruntinių vandenų slūgsojimo lygio fluktuacijos per pastaruosius 22 metus – 1907 m. nusausintoje ir 1999 m. patvenktoje šiaurinėje pelkės dalyje. Kontroliniai plotai išskirti centrinėje nesausintoje aukštapelkės dalyje. Čia vyrauja Eriophorum vaginatum-Sphagnum spp. (kupstinio švylio-kiminų) bendrijos su žemaūgėmis pušelėmis. Nustatyta, kad pagrindiniai meteorologiniai veiksniai, veikiantys vegetacijos periodo gruntinių vandenų fluktuacijas tiek natūraliuose, tiek sausinimu pažeistuose Kamanų aukštapelkės plotuose, yra oro drėgmės deficitas ir krituliai (R 2 = 0,416 – 0,761 p < 0,05). Per 7 metų periodą, praėjusį po 0,9–1,2 m gylio griovio, sausinusio aukštapelkę 92 m. blokavimo užtvaromis (1999 m.), gruntinių vandenų lygis 980 m pločio pagriovio zonoje, palyginus su kontrole, pakilo vidutiniškai 9,8–12,2 cm. Gruntinių vandenų atsistatymas iki kontrolinio lygio, blokavus griovius užtvaromis ekstensyviai nusausintose pelkės dalyse, įvyko per 4 metus, o intensyviai nusausintoje aukštapelkės dalyje, kaip rodo prognozės, įvyks apytiksliai per 12 m. Išaiškinta, kad į klimato šiltėjimą, t. y. į metinių temperatūrų didėjimą, nusausintų pelkių gruntiniai vandenys reaguoja labiau negu nenusausintų. Резюме Гидрологические исследования были проведены на верховом болоте государственного заповедника Каманос (56º16´N, 22º39´W), который находится на северо-западе Литвы. Площадь верхового болота – 1722 га. Целью работы было установить влияние метеорологических факторов и уничтожения осушительных канав на гидрологический режим верхового болота. Исходным материалом послужили данные о динамике уровня грунтовых вод за последние 22 года на в 1907 г. осушенных и в 1999 г. вновь затопленных площадях заповедника с болотными почвами. Контрольными площадями послужили нетронутые осушением участки болота, выделенные в центральной части заповедника, где преобладают сообщества пушицы и белого мха (Eriophorum vaginatum – Sphagnum spp.) с низкорослой сосной. Выявлено, что за 7-летний период, прошедший после уничтожения в 1999 г. осушительных канав глубиной 0,9–1,2 м, уровень грунтовых вод на приканавной полосе, равной 980 м, повысился в среднем на 9,8–12,2 см по сравнению с контрольным уровнем. Восстановление уровня грунтовых вод (до контрольного уровня) после уничтожения канав на экстенсивно осушенных площадях происходит спустя 4 года, а на интенсивно осушенных площадях – спустя 12 лет. Установлено, что на потепление климата, т. е. на повышение годовых температур, сильнее реагируют грунтовые воды осушенных болот, чем неосушенных.

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