DOI: 10.5061/dryad.s903c
title: Data from: N balance and cycling of Inner Mongolia typical steppe - a comprehensive case study of grazing effects

description: Increasing grazing pressure and climate change affect nitrogen (N)
 dynamics of grassland ecosystems in the Eurasian Steppe belt with unclear
 consequences for future delivery of essential services such as forage
 production, C sequestration, and diversity conservation. The
 identification of key processes responsive to grazing is crucial to
 optimize grassland management. In this comprehensive case study of a
 Chinese typical steppe, we present an in-depth analysis of grazing effects
 on N dynamics including the balance of N gains and losses, and N cycling.
 N pools and fluxes simultaneously quantified on three grassland sites of
 different long-term grazing intensities. Dust deposition, wind erosion,
 and wet deposition were predominant but most variable processes
 contributing to N losses and gains. Heavy grazing increased the risk of N
 losses by wind erosion. Haymaking and sheep excrements export to folds
 during night time keeping were important pathways of N losses from
 grassland sites. Compared to these fluxes, gaseous N losses (N2O, NO, N2
 and NH3), and N losses via export of sheep live weight and wool were of
 minor relevance. Our N balance calculation indicated mean annual net N
 losses of 0.9 ({plus minus}0.8) g N m-2 at the heavily grazed site,
 whereas the long-term ungrazed site was an N sink receiving mean annual
 inputs of 1.8 ({plus minus}1.1) g N m-2, mainly due to dust deposition.
 Heavy grazing reduced pool sizes of both topsoil organic N, and above- and
 belowground biomass and N fluxes with regard to plant N uptake,
 decomposition, gross microbial N turnover, and immobilization. Most
 N-related processes were more intensive in seasons of higher water
 availability indicating complex interactions between land use intensity
 and climate variability. The projected increase of atmospheric N
 depositions and changes in rainfall pattern superimposed by land use
 change will likely affect N sink-source pathways and N flux dynamics,
 indicating high potential impact on grassland ecosystem functions. Land
 use practices will be increasingly important for the management of N
 dynamics in Chinese typical steppe and, therefore, must be considered as
 key component to maintain, restore or optimize ecosystem services.
description: Giese et al
 2013_suppl_temperature and precipitation IMGERS
 1982-2003Monthly mean values of
 precipitation and temperature 1982-2003Giese et al
 2013_suppl_meteorological data IMGERS 2004-2006daily meteorological
 data of the experimental years 2004 -2006Giese et al
 2013_suppl_species_list_coverlist of plant species
 from the experimental sites in 2004 and 2006 with coverGiese et al
 2013_suppl_biomassbiomass data of the
 experimental sites from 2004 - 2006Giese et al
 2013_suppl_sheep N balance calculationexcel file to calculate
 sheep related N balancesGiese et al
 2013_suppl_figure 2a-c_colorppt.-file of the central
 figure in this articleGiese et al
 2013_suppl_image_Inner Mongolia grassland Xilin Riverpanorama image of the
 Xilingole grassland near the experimental sitesGiese et al
 2013_suppl_image_farm heavy grazingimage of the heavy
 grazing site with farm, sheep fold and grazing sheep
 herdGiese et al
 2013_suppl_image_sheep foldimage of a fold where
 sheep are kept over night and during part of the winterGiese et al
 2013_suppl_image_dung heapimage of a dung heap
 used for cooking and heating during winter