18 research outputs found
Data_Sheet_1_Interactive effects of catchment mean water residence time and agricultural area on water physico-chemical variables and GHG saturations in headwater streams.pdf
Greenhouse gas emissions from headwater streams are linked to multiple sources influenced by terrestrial land use and hydrology, yet partitioning these sources at catchment scales remains highly unexplored. To address this gap, we sampled year-long stable water isotopes (δ18O and δ2H) from 17 headwater streams differing in catchment agricultural areas. We calculated mean residence times (MRT) and young water fractions (YWF) based on the seasonality of δ18O signals and linked these hydrological measures to catchment characteristics, mean annual water physico-chemical variables, and GHG % saturations. The MRT and the YWF ranged from 0.25 to 4.77 years and 3 to 53%, respectively. The MRT of stream water was significantly negatively correlated with stream slope (r2 = 0.58) but showed no relationship with the catchment area. Streams in agriculture-dominated catchments were annual hotspots of GHG oversaturation, which we attributed to precipitation-driven terrestrial inputs of dissolved GHGs for streams with shorter MRTs and nutrients and GHG inflows from groundwater for streams with longer MRTs. Based on our findings, future research should also consider water mean residence time estimates as indicators of integrated hydrological processes linking discharge and land use effects on annual GHG dynamics in headwater streams.</p
Changes in the stable isotope ratios of (A) carbon and (B) nitrogen in four soil layers versus increasing vole numbers.
<p>The soil depth signature is the same in both charts. R<sup>2</sup> values correspond to the nearest signatures.</p
Vertical variability of (A) soil organic carbon content and (B) N contents at different numbers of voles.
<p>Vertical variability of (A) soil organic carbon content and (B) N contents at different numbers of voles.</p
(A) Soil bulk density (D<sub>B</sub>), (B) infiltration rate (IR) and saturated hydraulic conductivity (Ks), and (C) water holding capacity (WHC) with increasing number of voles per plot.
<p>Mean and SD of soil variables, in (B) only one-sided SD.</p
Results of the multiple regression with average number of voles (avnv) and elevation (elev) as independent variables.
<p>Results of the multiple regression with average number of voles (avnv) and elevation (elev) as independent variables.</p
Eleven biogeochemical key variables sampled from different soil compartments.
<p>Eleven biogeochemical key variables sampled from different soil compartments.</p
Development of vole populations within the eight plots based on repeated release, trapping and removal of voles between July 2010 and March 2012.
<p>Development of vole populations within the eight plots based on repeated release, trapping and removal of voles between July 2010 and March 2012.</p
Experimental frame to study bioturbation effects on key soil biogeochemical variables.
<p>(A) The set up of plots #1–#8. A 0.3 m elevation gradient existed across the plot arrangement. Within-plot sample pattern for C and N variables is outlined in plot #1. Reference soil samples were collected from agricultural fields without vole populations north of plot #1 and south of plot #4. (B) 21 months total vole numbers per 2500-m<sup>2</sup> plot. Very high and low vole numbers were achieved by repeated removal versus no removal of voles.</p
Giese et al 2013_suppl_biomass
biomass data of the experimental sites from 2004 - 200
Giese et al 2013_suppl_image_dung heap
image of a dung heap used for cooking and heating during winte