DOI: 10.5061/dryad.8812m
title: Data from: Soil trace gas fluxes along orthogonal precipitation and soil fertility gradients in tropical lowland forests of Panama

description: Tropical lowland forest soils are significant sources and sinks of trace
 gases. In order to model soil trace gas flux for future climate scenarios,
 it is necessary to be able to predict changes in soil trace gas fluxes
 along natural gradients of soil fertility and climatic characteristics. We
 quantified trace gas fluxes in lowland forest soils at five locations in
 Panama, which encompassed orthogonal precipitation and soil fertility
 gradients. Soil trace gas fluxes were measured monthly for 1 (NO) or 2
 (CO2, CH4, N2O) years (2010–2012) using vented dynamic (for NO only) or
 static chambers with permanent bases. Across the five sites, annual fluxes
 ranged from 8.0 to 10.2 Mg CO2-C, −2.0 to −0.3 kg CH4-C, 0.4 to 1.3 kg
 N2O-N and −0.82 to −0.03 kg NO-N ha−1 yr−1. Soil CO2 emissions did not
 differ across sites, but they did exhibit clear seasonal differences and a
 parabolic pattern with soil moisture across sites. All sites were CH4
 sinks; within-site fluxes were largely controlled by soil moisture,
 whereas fluxes across sites were positively correlated with an integrated
 index of soil fertility. Soil N2O fluxes were low throughout the
 measurement years, but the highest emissions occurred at a
 mid-precipitation site with high soil N availability. Net negative NO
 fluxes at the soil surface occurred at all sites, with the most negative
 fluxes at the low-precipitation site closest to Panama City; this was
 likely due to high ambient NO concentrations from anthropogenic sources.
 Our study highlights the importance of both short-term (climatic) and
 long-term (soil and site characteristics) factors in predicting soil trace
 gas fluxes.
description: Repeated
 measurementsRepeated field
 measurements of trace gas flux at the soil surface at five forest sites in
 Panama. Gases measured include: carbon dioxide (CO2; mg C m-2 hr-1),
 methane (CH4; ug C m-2 hr-1), nitrous oxide (N2O; ug N m-2 hr-1), nitric
 oxide (NO; ug N m-2 hr-1) and initial nitric oxide concentration (NOSt;
 ppb). Other data collected from the field: soil extractable nitrate (NO3;
 mg N kg-1) and ammonium (NH4; mg N kg-1), soil temperature (Temp; oC) and
 soil gravimetric water content (Moisture; g g-1). Site numbers correspond
 to the map shown in the supplementary material for this
 article.bg-2016-393
 repeated.xlsxOne-time soil
 measurementsOne-time measurements of
 soil biochemical characteristics in the top 50 cm of soil at five forest
 sites in Panama (site numbers shown correspond to the map provided in the
 supplementary data for this article). Characteristics include: natural
 abundance 15N (soil15N; ‰), 15N enrichment factor (see paper for detailed
 calculation), organic carbon (C; mg C g-1), total nitrogen (N; mg N g-1),
 carbon to nitrogen ratio (CN), effective cation exchange capacity (ECEC;
 mmolc kg-1), exchangeable bases (BS; mmolc kg-1), exchangeable element
 concentrations (Na, K, Ca, Mg, Fe, Mn, Al; mmolc kg-1), pH and particle
 size: sand, silt and clay (%).bg-2016-393
 soil.xlsx