2.3 Data calculation and analysis
In total, we combined 106 sites both from literature and field sampling
ranging from large temperature and precipitation gradients covering the
main grassland types in China. We divided the soil layer into four
groups, 0–10, 10–20, 20–30 and 30–100 cm. Most root biomass was
located in the surface soil (0–10 cm), then decreased along the soil
profile (10–20 and 20–30 cm), while only a little root biomass was in
the deep soil (30–100 cm). In addition, the soil data from most
documents were also collected according to these soil layers. The soil
samples belonged to six vegetation types (temperate meadow, temperate
typical steppe, temperate desert steppe, alpine meadow, alpine steppe
and alpine desert steppe) according to the dominant species, temperature
and moisture conditions. According to the duration of GE, we divided all
the sites into short- (≤5 years), medium- (5–15 years) and long-term
(≥15 years) periods. The RPC following GE were calculated with the
following formula: RPC (%) = (soil pHGE − soil
pHgrazing)/soil pHgrazing × 100%. The
rates of RCC, RNC, RAC and RBC changes following GE were calculated by
using a similar formula to that of RPC.
We determined the differences in soil pH between grazed and GE
grasslands for all samples and in each soil layer using pairedt -test. Differences in RPC between soil layers, durations of GE
and dominant species were analysed by one-way ANOVA and LSD tests. The
relationships of RPC to MAP, MAT, RCC, RNC, RAC and RBC were determined
by Pearson correlation analysis.