Plant Species Composition Can Be Used as a Proxy to Predict Methane Emissions in Peatland Ecosystems After Land-Use Changes

Abstract

Land-use change in peatlands affects important drivers of CH 4 emission such as groundwater level and nutrient availability. Due to the high spatial and temporal variability of such environmental drivers, it is hard to make good predictions of CH 4 emissions in the context of land-use changes. Here, we used plant species composition as a stable integrator of environmental drivers of CH 4 emissions. We used weighted averaging regression and calibration to make a direct link between plant species composition and CH 4 flux in an effort to predict values of CH 4 emission for a land-use gradient in two extensive peatland sites. Our predicted CH 4 emissions showed good fit with observed values. Additionally, we showed that a quick characterization of vegetation composition, by the dominant species only, provides equally good predictions of CH 4 emissions. The use of mean groundwater level alone for predicting emissions showed the same predictive power as our models. However, water level showed strong variability in time. Furthermore, the inverse relationship between water level and CH 4 emission can lead to higher errors in predictions at sites with higher CH 4 emission. The performance of our model was comparable with those of mechanistic models developed for natural wetland ecosystems. However, such mechanistic models require complex input parameters that are rarely available. We propose the use of plant species composition as a simple and effective alternative for deriving predictions of CH 4 emissions in peatlands in the context of land-use change.

Greenhouse Gas Fluxes from Dutch Peatland Water Bodies: Importance of the Surrounding Landscape

“…Veenendaal et al (2007), for example, assumed that intensively managed grassland on peat emits very little methane (0.005 mg CH 4 m −2 h −1 ). Schrier-Uijl et al (2010a) as well as Dias et al (2010) reported higher fluxes (~1 and 0.03 mg CH 4 m −2 h −1 ), but earlier work of suggest that intensively used well-drained grassland is a net sink for CH 4 (−0.003 mg CH 4 m −2 h −1 ). At the same time, these drained peatlands emit substantial quantities of CO 2 and N 2 O, and all should be included when estimating a full greenhouse gas balance (Hendriks et al 2007;Kechavarzi et al 2007;Veenendaal et al 2007).…”

“…Since water may cover anywhere between 6 and 43% in these peatlands (Vermaat and Hellmann 2010), our findings imply that landscapescale assessments of methane fluxes require separate estimates of terrestrial and aquatic fluxes, where the latter need to take into account productivity and groundwater table (Kechavarzi et al 2007) of the adjacent land. We did a tentative landscape-scale estimate using our own aquatic CH 4 fluxes at annual mean temperature, terrestrial estimates from Dias et al (2010), and a methane emission estimate for dairy cattle from Veenendaal et al (2007). We conclude that agricultural landscapes would emit more methane than natural wetlands only if the percentage of open water was above 65%.…”

“…Open water sites were excluded because coupling to flux estimates from adjacent land is not straightforward due to the absence of such nearby land. Error df=50 and 35, respectively Dias et al (2010) b carbon dioxide fluxes have not been adjusted to mean annual temperature, because the sensitivity of night-time fluxes to soil temperature was found to be substantially less than that of methane (Schrier-Uijl et al 2010a) methane fluxes from ditches in recently rewetted peatlands will mostly likely decline when fertilization stops and reduced nutrient loading also causes declining vegetation productivity. Accumulated nutrients in the peat soil (e.g., Vermaat and Hellmann 2010) will determine the time lag for this decline.…”

“…Flux observations from adjacent land were obtained from Dias et al (2010), who did nearby terrestrial incubations simultaneously or within the same week. Each water body was sampled only once during the season, hence extrapolation to annual fluxes would be problematic without addressing potentially considerable seasonal variation in wetland methane emission (Van den Hendriks et al 2007;SchrierUijl et al 2010a).…”

Assessing greenhouse gas emissions from peatlands using vegetation as a proxy

“…Metaanalysis of available annual CO 2 flux data denied a distinction between bog and fen sites; fluxes rather are determined by water level, allowing the use of 'bog' measurements to specify CO 2 fluxes from 'fen' sites and vice versa. A strong relationship between dominant plant species and methane emissions has been described for two Dutch peatlands (Dias et al, 2010). The presence or absence of aerenchymous shunt species provides a first simple division of vegetation and flux data, which enables assigning flux values to vegetation types not covered by direct flux measurements.…”