The Impact of Water Content on Sources of Heterotrophic Soil Respiration
| dc.contributor.author | McElligott, Kristin M. | en |
| dc.contributor.author | Seiler, John R. | en |
| dc.contributor.author | Strahm, Brian D. | en |
| dc.contributor.department | Forest Resources and Environmental Conservation | en |
| dc.date.accessioned | 2017-09-20T18:34:34Z | en |
| dc.date.available | 2017-09-20T18:34:34Z | en |
| dc.date.issued | 2017-08-16 | en |
| dc.date.updated | 2017-09-20T18:34:34Z | en |
| dc.description.abstract | Heterotrophic respiration (R<sub>H</sub>) is a major flux of CO<sub>2</sub> from forest ecosystems and represents a large source of uncertainty in estimating net ecosystem productivity (NEP) using regional soil respiration (R<sub>S</sub>) models. R<sub>H</sub> from leaf litter (R<sub>HL</sub>) may contribute greatly to annual R<sub>H</sub> estimates, but its contribution may be misrepresented due to the logistical and technical challenges associated with chamber-based field measurements of R<sub>HL</sub>. The purpose of this study was to evaluate the sensitivity of sources of R<sub>H</sub> (mineral soil-derived heterotrophic respiration [R<sub>HM</sub>] and leaf litter-derived heterotrophic respiration [R<sub>HL</sub>]) of a loblolly pine plantation (Pinus taeda L.) to varying soil and litter water content over the course of a dry down event. Additionally, we investigated whether fertilization influenced R<sub>HL</sub> and R<sub>HM</sub> to understand how forest nutrient management may impact forest soil carbon (C) dynamics. R<sub>HL</sub> was measured under dry conditions and at field capacity to evaluate water content controls on R<sub>HL</sub>, determine the duration of increased CO<sub>2</sub> release following wetting, and evaluate the potential contribution to total R<sub>H</sub>. We also measured R<sub>HM</sub> inside collars that excluded plant roots and litter inputs, from field capacity until near-zero R<sub>HM</sub> rates were attained. We found that R<sub>HL</sub> was more sensitive to water content than R<sub>HM</sub>, and increased linearly with increasing litter water content (R<sup>2</sup> = 0.89). The contribution of R<sub>HL</sub> to R<sub>H</sub> was greatest immediately following the wetting event, and decreased rapidly to near-zero rates between 3 and 10 days. R<sub>HM </sub>also had a strong relationship with soil water content (R<sup>2</sup> = 0.62), but took between 200 and 233 days to attain near-zero R<sub>HM</sub> rates. Fertilization had no effect on R<sub>HM </sub>(<i>p</i> = 0.657), but significantly suppressed R<sub>HL</sub> rates after the wetting event (<i>p</i> < 0.009). These results demonstrate that there is great temporal variability in both CO<sub>2</sub> released and the water content of differing sources of R<sub>H</sub>, and forest fertilization may largely impact forest floor C stocks. This variability may not be captured reliably using conventional weekly to monthly chamber-based field sampling efforts and could lead to over- or underestimation of R<sub>H</sub>. In the context of climate change, changes in the frequency and intensity of wetting and drying events will likely alter R<sub>HL</sub> and its contribution to R<sub>S</sub>. Separate consideration of R<sub>H</sub> sources and controls, along with increased field sampling frequency using chamber-based methodology under a broader range of specific environmental conditions, are likely needed to reduce variability in R<sub>H</sub> estimates and improve the accuracy of forest NEP predictions. | en |
| dc.description.version | Published version | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.citation | McElligott, K.M.; Seiler, J.R.; Strahm, B.D. The Impact of Water Content on Sources of Heterotrophic Soil Respiration. Forests 2017, 8, 299. | en |
| dc.identifier.doi | https://doi.org/10.3390/f8080299 | en |
| dc.identifier.uri | http://hdl.handle.net/10919/79346 | en |
| dc.language.iso | en | en |
| dc.publisher | MDPI | en |
| dc.rights | Creative Commons Attribution 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by/4.0/ | en |
| dc.subject | carbon cycle | en |
| dc.subject | fertilization | en |
| dc.subject | soil CO2 efflux | en |
| dc.subject | leaf litter | en |
| dc.subject | loblolly pine plantations | en |
| dc.title | The Impact of Water Content on Sources of Heterotrophic Soil Respiration | en |
| dc.title.serial | Forests | en |
| dc.type | Article - Refereed | en |
| dc.type.dcmitype | Text | en |