West Kalimantan, Indonesia
West Kalimantan, Indonesia

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Ponette-Gonzalez A.G.,University of North Texas | Curran L.M.,Stanford University | Pittman A.M.,Stanford University | Carlson K.M.,University of Hawaii at Manoa | And 4 more authors.
Environmental Research Letters | Year: 2016

Biomass burning plays a critical role not only in atmospheric emissions, but also in the deposition and redistribution of biologically important nutrients within tropical landscapes.Wequantified the influence of fire on biogeochemical fluxes of nitrogen (N), phosphorus (P), and sulfur (S) in a 12 ha forested peatland inWest Kalimantan, Indonesia. Total (inorganic + organic)N, NO3 -N, NH4 + -N, total P, PO4 3 -P, and SO4 2 --S fluxes were measured in throughfall and bulk rainfall weekly from July 2013 to September 2014. To identify fire events, we used concentrations of particulate matter (PM10) and MODIS Active Fire Product counts within 20 and 100 kmradius buffers surrounding the site. Dominant sources of throughfall nutrient deposition were explored using cluster and backtrajectory analysis. Our findings show that this Bornean peatland receives some of the highest P (7.9 kg PO4 3- -P ha-1yr-1) and S (42 kg SO4 -2 -S ha-1yr-1) deposition reported globally, and thatN deposition (8.7 kg inorganic N ha-1yr-1) exceeds critical load limits suggested for tropical forests. Six major dry periods and associated fire events occurred during the study. Seventy-eight percent of fires within 20 kmand 40% within 100 kmof the site were detected within oil palm plantation leases (industrial agriculture) on peatlands. These fires had a disproportionate impact on below-canopy nutrient fluxes. Post-fire throughfall events contributed>30%of the total inorganicN (NO3 -N+ NH4 + -N) and PO4 3- -P flux to peatland soils during the study period. Our results indicate that biomass burning associated with agricultural peat fires is a major source of N, P, and S in throughfall and could rival industrial pollution as an input to these systems during major fire years. Given the sheer magnitude of fluxes reported here, fire-related redistribution of nutrients may have significant fertilizing or acidifying effects on a diversity of nutrient-limited ecosystems. © 2016 IOP Publishing Ltd.

Carlson K.M.,University of Minnesota | Carlson K.M.,Yale University | Carlson K.M.,Stanford University | Curran L.M.,Yale University | And 9 more authors.
Journal of Geophysical Research: Biogeosciences | Year: 2014

Oil palm plantation expansion into tropical forests may alter physical and biogeochemical inputs to streams, thereby changing hydrological function. In West Kalimantan, Indonesia, we assessed streams draining watersheds characterized by five land uses: intact forest, logged forest, mixed agroforest, and young (<3 years) and mature (>10 years) oil palm plantation. We quantified suspended sediments, stream temperature, and metabolism using high-frequency submersible sonde measurements during month-long intervals between 2009 and 2012. Streams draining oil palm plantations had markedly higher sediment concentrations and yields, and stream temperatures, compared to other streams. Mean sediment concentrations were fourfold to 550-fold greater in young oil palm than in all other streams and remained elevated even under base flow conditions. After controlling for precipitation, the mature oil palm stream exhibited significantly greater sediment yield than other streams. Young and mature oil palm streams were 3.9°C and 3.0°C warmer than the intact forest stream (25°C). Across all streams, base flow periods were significantly warmer than times of stormflow, and these differences were especially large in oil palm catchments. Ecosystem respiration rates were also influenced by low precipitation. During an El Niño-Southern Oscillation-associated drought, the mature oil palm stream consumed a maximum 21 g O2 m-2 d-1 in ecosystem respiration, in contrast with 2.8-±-3.1 g O2 m-2 d-1 during nondrought sampling. Given that 23% of Kalimantan's land area is occupied by watersheds similar to those studied here, our findings inform potential hydrologic outcomes of regional periodic drought coupled with continued oil palm plantation expansion. ©2014. American Geophysical Union. All Rights Reserved.

Gaveau D.L.A.,Stanford University | Curran L.M.,Stanford University | Paoli G.D.,Daemeter Consulting | Carlson K.M.,Stanford University | And 5 more authors.
Conservation Letters | Year: 2012

Several studies suggest that protected areas conserve forests because deforestation rates are lower inside than outside protected area boundaries. Such benefits may be overestimated when deforestation rates within protected areas are contrasted with rates in lands where forest conversion is sanctioned. Here, we reexamine protected area performance by disentangling the effects of land use regulations surrounding the 110,000 km2 protected area network in Sumatra, Indonesia. We compared 1990-2000 deforestation rates across: (1) protected areas; (2) unprotected areas sanctioned for conversion; and (3) unprotected production areas where commercial logging is permitted but conversion is not. Deforestation rates were lower in protected areas than in conversion areas (Mean: -19.8%; 95% C.I.: -29.7--10.0%; P < 0.001), but did not differ from production areas (Mean: -3.3%; 95% C.I.: -9.6-2.6%; P= 0.273). The measured protection impact of Sumatran protected areas differs with land use regulations governing unprotected lands used for comparisons. If these regulations are not considered, protected areas will appear increasingly effective as larger unprotected forested areas are sanctioned for conversion and deforested. In the 1990s, production areas were as effective as protected areas at reducing deforestation. We discuss implications of these findings for carbon conservation. © 2012 Wiley Periodicals, Inc.

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