Interannual variability in water and biogeochemical inputs to a coastal Bornean peatland

Alexandra G. Ponette-González, University of North Texas, alexandra.ponette@unt.edu
Lisa M. Curran, Stanford University, lmcurran@stanford.edu (Presenter)
Kimberly M. Carlson, University Minnesota, carlsonk@umn.edu
Alice M. Pittman, Stanford University, apittman@stanford.edu
Bethel Steele, Unaffiliated, bethelsteele@gmail.com
Dwi Astiani, Tanjungpura University, astiani.dwi@gmail.com
Dessy Ratnasari, Living Landscapes Indonesia, dessy.rasel@gmail.com
Mugiman , Living Landscapes Indonesia

Through alterations in water input and atmospheric concentrations, burning and precipitation variability associated with the El Niño Southern Oscillation (ENSO) may fundamentally alter biogeochemical inputs to ombrogenous Bornean peatlands. In these exclusively rainfed ecosystems, water delivers nutrients and pollutants to the forest floor and is critical to maintain water tables that mitigate vulnerability to fire and soil carbon loss. Here, we provide preliminary findings on water and chemical fluxes to and fire frequency surrounding a 12 ha forested peatland in West Kalimantan, Indonesia. Rainfall data (1980-2014) from the nearest meteorological station were used to assess ENSO effects on rainfall variability. In addition, bulk rainfall and throughfall water flux to soil were measured weekly to monthly during four water years (WY, months September-August) dominated by El Niño (WY1, 2009-2010), La Niña (WY2, 2010-2011), and neutral (WY3/4, 2012-2014) conditions. Sulfate-S, chloride, nitrogen, and phosphorus fluxes in rainfall and throughfall were measured from 2012-2014. We used the MODIS Active Fire Product (MCD14ML) to determine the number of fire locations within 20 km of the site. Long-term data indicate considerable interannual rainfall variability, from neutral years to strong El Niño or La Niña years. During dry season months (July-September), when fire activity increases, rainfall is significantly (~63%) lower during El Niño compared to neutral conditions. Surprisingly, neither bulk rainfall nor throughfall measured in this peatland differed significantly among water years or dry seasons. However, dry season water fluxes were 15-25% lower during WY1 than WY4 and 38-47% higher during WY2 than WY3. In contrast to water inputs, rain- and throughfall S concentrations were significantly higher in WY4 than WY3, resulting in nearly twofold greater S flux to the forest floor in WY4 (40 kg/ha) compared to WY3 (26 kg/ha). While twice as many fires were detected around the site in WY4 (303 fires) than in WY3 (115 fires), monthly fire totals and sulfate concentrations were not correlated, suggesting that S sources other than biomass burning, such as volcanoes, contributed to elevated S inputs. On-going analyses will evaluate how shifts in water fluxes, fires, and other emissions sources alter chemical fluxes to this Bornean peatland.

Presentation: 2015_Poster_PonetteGonzlez_76_182.pdf (1435k)

Presentation Type:  Poster

Session:  General Contributions   (Tue 4:35 PM)

Associated Project(s): 

• Curran, Lisa: Socio-economic and political drivers of oil palm expansion in Indonesia: Effects on rural livelihoods, carbon emissions and REDD ...details

Poster Location ID: 76