2.3 Soil collection and indoor analysis
In this study, we first selected three sample sites with approximately
the same plant community composition within each of the five sample
plots of MS, 5yrs, 11yrs, 22yrs, and 46yrs, and sampled the same soil
stratum in three replicates at each sample site in 20 cm strata. The
soil collected in each stratum was mixed thoroughly and divided into two
groups of samples within the three sample points of the five forest age
sample plots. One group measured the SIC content and the other group
tested soil moisture. To determine the soil volume, we collected
complete soil samples using a stainless steel soil sampler with a volume
of 100 cm3. After collecting the soil, we air dried it
and passed it through a 2 mm sieve to remove any rocks or root systems
larger than 2 mm. To analyze these samples, we ground them with a ball
mill and passed them through a 100 mesh soil sieve. Soil inorganic
carbon was determined by the air volumetric method, soil pH (water to
soil ratio of 2.5:1) was determined by the electrode method, and soil
bulk weight was the dry mass per unit volume of soil at 105°C. Soil
moisture was determined by weighing the fresh weight of the soil, then
drying it at 105°C and weighing the dry weight.