Response of soil respiration to changes in soil temperature and water table level in drained and restored peatlands of the southeastern United States

Abstract

Background Extensive drainage of peatlands in the southeastern United States coastal plain for the purposes of agriculture and timber harvesting has led to large releases of soil carbon as carbon dioxide (CO2) due to enhanced peat decomposition. Growth in mechanisms that provide financial incentives for reducing emissions from land use and land-use change could increase funding for hydrological restoration that reduces peat CO2 emissions from these ecosystems. Measuring soil respiration and physical drivers across a range of site characteristics and land use histories is valuable for understanding how CO2 emissions from peat decomposition may respond to raising water table levels. We combined measurements of total soil respiration, depth to water table from soil surface, and soil temperature from drained and restored peatlands at three locations in eastern North Carolina and one location in southeastern Virginia to investigate relationships among total soil respiration and physical drivers, and to develop models relating total soil respiration to parameters that can be easily measured and monitored in the field. Results Total soil respiration increased with deeper water tables and warmer soil temperatures in both drained and hydrologically restored peatlands. Variation in soil respiration was more strongly linked to soil temperature at drained (R2 = 0.57, p < 0.0001) than restored sites (R2 = 0.28, p < 0.0001). Conclusions The results suggest that drainage amplifies the impact of warming temperatures on peat decomposition. Proxy measurements for estimation of CO2 emissions from peat decomposition represent a considerable cost reduction compared to direct soil flux measurements for land managers contemplating the potential climate impact of restoring drained peatland sites. Research can help to increase understanding of factors influencing variation in soil respiration in addition to physical variables such as depth to water table and soil temperature.

Integrated water management practice in tropical peatland agriculture has low carbon emissions and subsidence rates

“…Carlson et al (2015) indicated that peat depth and time since draining are not significant predictors, while vegetation age is a strong predictor due to the rate of root respiration [ 56 ]. Swails et al (2022) observed that soil respiration on peatland is linked to soil temperature [ 81 ]. This research also determined that water content, with an average water content during the six-month research period of 273% ± 79%, is not a significant predictor of CO 2 emission estimation (R 2 = 0.000, p value = 0.773).…”

Sphagnum mosses, the impact of disturbances and anthropogenic management actions on their ecological role in CO2 fluxes generated in peatland ecosystems

“…Hydrological alteration generated by drainage is one of the most generalized anthropogenic disturbances and the one that produces the greatest damage on a peatland because primary productivity and OM degradation are closely linked to WT position (Evans et al., 2021; Huang et al., 2021; Laiho, 2006; Loisel et al., 2021; Strack & Price, 2009). The decline in WT generally alters the dynamics and C balance of the ecosystem (Chimner et al., 2017; Goodrich et al., 2015; Minkkinen et al., 1999; Strachan et al., 2016), because increased oxygen availability in the unsaturated surface stratum (acrotelm) favors respiration and oxidation of OM, increasing CO 2 emissions (Figure 3) (Huang et al., 2021; Ma et al., 2022; Peichl et al., 2014; Strack et al., 2014; Swails et al., 2022). On the other hand, anaerobic conditions fostered by elevated WT favor the accumulation of recalcitrant compounds derived from Sphagnum by inhibiting OM degradation through a mechanism known as “enzymatic latch” (Abbott et al., 2013; Freeman et al., 2001; Kim et al., 2021).…”

Total Soil CO2 Efflux from Drained Terric Histosols

“…Total soil CO 2 efflux is the second largest carbon flux (after photosynthesis) in terrestrial ecosystems [ 16 ] and is a result of autotrophic (CO 2 produced by vegetation living roots) and heterotrophic (CO 2 produced by soil microbes in the decomposition of organic matter deposited into soil and on the soil surface) soil respiration [ 17 , 18 , 19 ]. The total soil respiration rate depends on many variables such as local climate, land use, nutrient availability, soil temperature, soil moisture, and water table level (WTL) [ 20 , 21 , 22 , 23 ]. Generally, lower WTL in drained areas has a positive effect on oxygen availability, which can enhance oxidation and decomposition at greater peat layer depth from the soil surface [ 24 , 25 ].…”