Study Site
Our study took place within a long-term grazing experiment located in
Siziwang Banner (41°46’43 ”N, 111°53’42” E, elevation 1456 m) at the
comprehensive experiment and demonstration center of the Inner Mongolia
Academy of Agriculture and Animal Husbandry Sciences, China. The study
site is a typical desert steppe ecosystem dominated by Stipa
breviflora Griseb., Artemisia frigida Willd, andCleistogenes songorica (Roshev.) Ohwi. Subordinate species
include Convolvulus ammannii Desr., Kochia prostrata (L.)
Schrad., Caragana stenophylla Pojark. and Caragana
microphylla Lam.. The soil is primarily a sandy loam texture with low
nitrogen, phosphorus, and organic matter content, but high potassium.
Over the course of the experiment (2004 to 2020), the average annual
temperature was 3.4℃ and the average annual precipitation was 221.7 mm
(the majority falling from June to August). We present the air
temperature and precipitation during the growing season in which we
collected data (2020) in Fig. S1.
Experimental Design
A grazing manipulation experiment was established in June 2004 in a
natural grassland (~50 ha) with relatively flat terrain
and relatively homogeneous vegetation and soil types. The plots were
divided into three experimental blocks which each received one of four
grazing treatments, control (no grazing), light grazing, medium grazing
and heavy grazing (thus, there were three replicates for each
treatment). Each experimental plot was 4.4 ha and constructed with iron
wire fencing material. The stocking rates in each treatment were 0
(control/ no grazing), 0.91 (light grazing), 1.82 (moderate grazing, MG)
and 2.71 (heavy grazing) sheep unit · (hm2A-1) -1. Each grazing plot was
grazed by adult sheep from June 1 to October 1 each year. During the
grazing season, the sheep were driven into the grazing area at 6:00
every day and left to forage freely until their return to the corral at
18:00.