2. Methods and materials
2.1. Soil and edible mushrooms sampling
The fruiting bodies of edible mushroom samples and the underlying
soil samples were collected from 16 locations in Yunnan
Province (eight species in total). The sampling locations, mushroom
species and habitats are shown in Table 1. For the identification
of specimens, the color, odor and other apparent properties of
the mushrooms were noted. The mushrooms were identified using
reference books (Mao, 2000, chap. 1–5). The study area included
forests distant from sources of industrial pollution. During the
sampling process, the edible mushroom samples were collected
at the same growth stage, and old or damaged mushrooms were
not included in the samples. The underlying soil samples were collected
to include a depth of 0–20 cm.
After collection, the mushroom and soil samples were prepared
for chemical analysis. The soil samples were first air-dried at room
temperature until their weights were constant; the stones and
plant materials were then removed, and each sample was sieved
using 1-mm nylon mesh for further analysis. As for the mushroom
samples, the fruiting bodies were carefully cleaned to remove any
surface contamination and subsequently dried at 105 C until a
constant weight was obtained. All of the samples were then ready
for further analysis.