An official website of the United States government
Abstract Tree stems exchange CO2, CH4and N2O with the atmosphere but the magnitudes, patterns and drivers of these greenhouse gas (GHG) fluxes remain poorly understood. Our understanding mainly comes from static-manual measurements, which provide limited information on the temporal variability and magnitude of these fluxes. We measured hourly CO2, CH4and N2O fluxes at two stem heights and adjacent soils within an upland temperate forest. We analyzed diurnal and seasonal variability of fluxes and biophysical drivers (i.e., temperature, soil moisture, sap flux). Tree stems were a net source of CO2(3.80 ± 0.18 µmol m−2s−1; mean ± 95% CI) and CH4(0.37 ± 0.18 nmol m−2s−1), but a sink for N2O (−0.016 ± 0.008 nmol m−2s−1). Time series analysis showed diurnal temporal correlations between these gases with temperature or sap flux for certain days. CO2and CH4showed a clear seasonal pattern explained by temperature, soil water content and sap flux. Relationships between stem, soil fluxes and their drivers suggest that CH4for stem emissions could be partially produced belowground. High-frequency measurements demonstrate that: a) tree stems exchange GHGs with the atmosphere at multiple time scales; and b) are needed to better estimate fluxes magnitudes and understand underlying mechanisms of GHG stem emissions.
more »
« less
Dataset: Spatiotemporal variability and origin of CO2 and CH4 tree stem fluxes in an upland forest
The exchange of multiple greenhouse gases (i.e., CO2 </sub>and CH4</sub>) between tree stems and the atmosphere represents a knowledge gap in the global carbon cycle. Stem CO2</sub> and CH4</sub> fluxes vary across time and space and is unclear which are their individual or shared drivers. This dataset contains information of CO2</sub> and CH4</sub> fluxes at different stem heights combining manual (biweekly; n=678) and automated (hourly; n>38,000) measurements in a temperate upland forest.</div>This study was performed in an upland forested area at the St. Jones Reserve [39°5’20”N, 75°26’21”W], a component of the Delaware National Estuarine Research Reserve (DNERR).</div></div>The dominant vegetation species are bitternut hickory (Carya cordiformis</i>), eastern red cedar (Juniperus virginiana</i> L.), American holly (Ilex opaca</i> (Ashe)), sweet gum (Liquidambar styraciflua</i> L.) and black gum (Nyssa sylvatica</i> (Marshall)), with an overall tree density of 678 stems ha-1</sup> and mean diameter at breast height (DBH) of 25.7±13.9 cm (mean±sd). We studied bitternut hickory, which is one of the most important species in the study site, accounting for 24.9% of the total basal area.</div></div>For code </div>
more »
« less
- Award ID(s):
- 1652594
- PAR ID:
- 10395725
- Publisher / Repository:
- figshare
- Date Published:
- Subject(s) / Keyword(s):
- 50301 Carbon Sequestration Science 40104 Climate Change Processes 50101 Ecological Impacts of Climate Change 50102 Ecosystem Function 50206 Environmental Monitoring Environmental Science 70599 Forestry Sciences not elsewhere classified 70508 Tree Nutrition and Physiology
- Format(s):
- Medium: X Size: 9579835 Bytes
- Size(s):
- 9579835 Bytes
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Coastal salt marshes store large amounts of carbon but the magnitude and patterns of greenhouse gas (GHG; i.e., carbon dioxide (CO2</sub>) and methane (CH4</sub>)) fluxes are unclear. Information about GHG fluxes from these ecosystems comes from studies of sediments or at the ecosystem-scale (eddy covariance) but fluxes from tidal creeks are unknown. </div>This dataset includes GHG concentrations in water, water quality, meteorology, sediment CO2</sub> efflux, ecosystem-scale GHG fluxes, and plant phenology; all at half-hour time-steps over one year.</div></div>This study was carried out in the St. Jones Reserve, a component of the Delaware National Estuarine Research Reserve in Dover, Delaware, U.S.A. The study site is part of the following networks:</div></div>- AmeriFlux (https://ameriflux.lbl.gov/sites/siteinfo/US-StJ) </div>- Phenocam (https://phenocam.sr.unh.edu/webcam/sites/stjones/) </div></div>The GHG concentration and efflux sampling point was located at Aspen Landing within a microtidal (mean tide range of 1.5 m), mesohaline (typical salinity of 5-18 ppt) salt marsh (Delaware Department of Natural Resources and Environmental Control, 2006) tidal creek.</div></div>Main reference:</div> Trifunovic, B., Vázquez‐Lule, A., Capooci, M., Seyfferth, A. L., Moffat, C., & Vargas, R. (2020). Carbon dioxide and methane emissions from a temperate salt marsh tidal creek. Journal of Geophysical Research: Biogeosciences, 125, e2019JG005558. https://doi.org/ 10.1029/2019JG005558 </p> </div> </div> </div></div>more » « less
-
Abstract Sea level rise and more frequent and larger storms will increase saltwater flooding in coastal terrestrial ecosystems, altering soil‐atmosphere CO2and CH4exchange. Understanding these impacts is particularly relevant in high‐latitude coastal soils that hold large carbon stocks but where the interaction of salinity and moisture on greenhouse gas flux remains unexplored. Here, we quantified the effects of salinity and moisture on CO2and CH4fluxes from low‐Arctic coastal soils from three landscape positions (two Wetlands and Upland Tundra) distinguished by elevation, flooding frequency, soil characteristics, and vegetation. We used a full factorial laboratory incubation experiment of three soil moisture levels (40%, 70%, or 100% saturation) and four salinity levels (freshwater, 3, 6, or 12 ppt). Salinity and soil moisture were important controls on CO2and CH4emissions across all landscape positions. In saturated soil, CO2emissions increased with salinity in the lower elevation landscape positions but not in the Upland Tundra soil. Saturated soil was necessary for large CH4emissions. CH4emissions were greatest with low salinity, or after 11 weeks of incubation when SO42−was exhausted allowing for methanogenesis as the dominant mechanism of anaerobic respiration. In partially saturated soil, greater salinity suppressed CO2production in all soils. CH4fluxes were overall quite low, but increased between 3 and 6 ppt in the Tundra. In the future, a small increase in floodwater salinity may increase CO2production while suppressing CH4production; however, where water is impounded, CH4production could become large, particularly in the landscapes most likely to flood.more » « less
-
Abstract Small freshwater reservoirs are ubiquitous and likely play an important role in global greenhouse gas (GHG) budgets relative to their limited water surface area. However, constraining annual GHG fluxes in small freshwater reservoirs is challenging given their footprint area and spatially and temporally variable emissions. To quantify the GHG budget of a small (0.1 km2) reservoir, we deployed an Eddy covariance (EC) system in a small reservoir located in southwestern Virginia, USA over 2 years to measure carbon dioxide (CO2) and methane (CH4) fluxes near‐continuously. Fluxes were coupled with in situ sensors measuring multiple environmental parameters. Over both years, we found the reservoir to be a large source of CO2(633–731 g CO2‐C m−2 yr−1) and CH4(1.02–1.29 g CH4‐C m−2 yr−1) to the atmosphere, with substantial sub‐daily, daily, weekly, and seasonal timescales of variability. For example, fluxes were substantially greater during the summer thermally stratified season as compared to the winter. In addition, we observed significantly greater GHG fluxes during winter intermittent ice‐on conditions as compared to continuous ice‐on conditions, suggesting GHG emissions from lakes and reservoirs may increase with predicted decreases in winter ice‐cover. Finally, we identified several key environmental variables that may be driving reservoir GHG fluxes at multiple timescales, including, surface water temperature and thermocline depth followed by fluorescent dissolved organic matter. Overall, our novel year‐round EC data from a small reservoir indicate that these freshwater ecosystems likely contribute a substantial amount of CO2and CH4to global GHG budgets, relative to their surface area.more » « less
-
Abstract With the goal of generating anionic analogues to MN2S2⋅Mn(CO)3Br we introduced metallodithiolate ligands, MN2S22−prepared from the Cys‐X‐Cys biomimetic, ema4−ligand (ema=N,N′‐ethylenebis(mercaptoacetamide); M=NiII, [VIV≡O]2+and FeIII) to Mn(CO)5Br. An unexpected, remarkably stable dimanganese product, (H2N2(CH2C=O(μ‐S))2)[Mn(CO)3]2resulted from loss of M originally residing in the N2S24−pocket, replaced by protonation at the amido nitrogens, generating H2ema2−. Accordingly, the ema ligand has switched its coordination mode from an N2S24−cavity holding a single metal, to a binucleating H2ema2−with bridging sulfurs and carboxamide oxygens within Mn‐μ‐S‐CH2‐C‐O, 5‐membered rings. In situ metal‐templating by zinc ions gives quantitative yields of the Mn2product. By computational studies we compared the conformations of “linear” ema4−to ema4−frozen in the “tight‐loop” around single metals, and to the “looser” fold possible for H2ema2−that is the optimal arrangement for binucleation. XRD molecular structures show extensive H‐bonding at the amido‐nitrogen protons in the solid state.more » « less
