Deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes

Abstract

Gauci, Vincent. 2013 Deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes. Nature, 493. 660-663. 10.1038/nature11818Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. 39Unlike boreal and temperate forests 5,6 , and higher latitude wetlands 7 , however, the loss of fluvial 40 organic carbon from tropical peats has yet to be fully quantified. 41To quantify the effect of peatland degradation on fluvial organic C loss, we monitored DOC and , and experienced similar annual rainfall (Table 1). 9TOC ( ; Fig. 1). This represents a 55% increase in 12TOC export from the disturbed sites (DPSF1 and 2) over IPSF. Of the annual TOC flux from each land-13 cover class, 94% was lost during the wet season (October-June), the result of higher measured 14 discharge rates (3.9 m 3 s -1 cf. 1.0 m 3 s -1 in the dry season). This was associated with high rainfall 15 rather than changes in C concentration, which remained relatively constant over the study period. 16As with seasonal flux variability, differences in discharge between land-cover classes determined TOC 17flux with higher discharge rates causing larger fluxes in DPSF1 and DPSF2 (1744 mm and 1724 mm, 18respectively) than in IPSF (907 mm). These higher discharge rates in disturbed land-cover classes 19were not counterbalanced by lower TOC concentrations, and occurred despite uniform rainfall across 20 sites (Table 1). This likely reflects a decline in evapotranspiration and increased runoff as a 21consequence of large scale biomass loss and drainage in both disturbed land-cover classes. DOC 22accounted for between 91-98 % of the TOC lost, with lower DOC:POC ratios for disturbed sites ( Table 23 1) suggesting that the drained and exposed peat is vulnerable to mechanical breakdown associated 24 with the increased runoff. 25Surface water DOC can derive from multiple sources, ranging from recent photosynthates to 26 decomposition or dissolution products from deep within the peat column. We used radiocarbon ( 3These data indicate that the increased DOC fluxes from disturbed peatlands are derived from 4 previously stable C stored within the peat column, and suggest that this loss of C from depth is 5 occurring throughout the seasonal hydrologic cycle. Application of an age attribution model (Fig. 2d) 6suggests that two-thirds of DOC in runoff from the DPSF2 site derives from peat carbon of 500-5000 7 years age. 35To quantify the impact peatland disturbance has had on regional long-term fluvial C loss, we applied 36 our TOC flux estimates to land areas of intact and deforested PSF prior to and after peatland 37 disturbance. We omitted industrial plantations from our calculations as, to our knowledge, there are 38 no quantitative data on fluvial C flux from this land cover class, although our DO 14 C data suggest that 39 these ecosystems may also ...

Fighting carbon loss of degraded peatlands by jump-starting ecosystem functioning with ecological restoration

“…Significant changes like elevated total concentrations of nitrogen (N) and phosphorus (P) and decreased concentrations of major exchangeable cations such as potassium (K), calcium (Ca), and magnesium (Mg) are observed in the surface peat after drainage (Laiho et al 1999, Sundström et al 2000. pH and concentrations of several chemical elements increase in the pore and outflow water shortly after drainage , Moore et al 2013. In contrast, long-term changes of pore water chemistry after drainage are not well understood (Holden et al 2004).…”

“…Waddington & Day, 2007) and fluvial DOC fluxes (e.g. Moore et al, 2013) as well as the development of tree stands (e.g. are also needed to reliably estimate if peatland restoration may really produce tradable C-related ecosystem services.…”

“…Because of the lowered water table level, drainage increases aeration and promotes decomposition and nutrient mineralization in the peat matrix . Subsequently, pH and concentrations of several chemical elements increase in the pore and outflow water shortly after drainage Holden et al 2004;Moore et al 2013). In contrast, long-term changes of pore water chemistry after drainage are not well understood (Holden et al 2004).…”

“…). However, wide-scale degradation caused by land-use threatens the C pool of peatlands on a global scale (Moore et al, 2013;Hooijer et al, 2010;Minkkinen et al, 2008;Oleszczuk et al, 2008). For example, ca.…”

Research agendas for the sustainable management of tropical peatland in Malaysia

“…There is growing international recognition of the important ecosystem services played by peatland environments, such as potable water supply (Rosli et al 2010;Silvius & Suryadiputra 2010), biodiversity (Page et al 2012) and carbon storage (Billett et al 2010;Page et al 2011a, b;Moore et al 2013). This increased recognition is reflected in a surge of policies and initiatives to maintain the integrity of peat across temperate and tropical peat zones.…”