2.1 Study site
Three sites have been chosen for field experiments based on the careful
consideration of geological, geomorphic, and climatic conditions in
Guizhou Province, central Southwest China (Figure 1). Table 1 shown the
main geographic environment information of three experiment sites. Site
A (27°15′37″N, 105°5′58″E) lies to the Northwest Guizhou, with a
relatively cold and dry climate. The topography surrounding the
experiment site is a typical karst valley, mostly composed of carbonate
rock. Azonal yellow soil covers a large area of Site A, which varied
from a few centimeters to approximately one meter in depth. Apart from a
thick soil layer in the valley bottom, there is not much soil on steep
slopes. The valley has a mixed coniferous and broad-leaved forest on the
upper part of the hillside, and a few patchy shrub or grass cover
underneath. Site B (26°33′1″N, 106°19′18″E) is located in a relatively
temperate climate region in the central of Guizhou province. A field
experiment of Site B was conducted in a giant karst valley. The exposed
rock of the valley is relatively pure limestone, which is in contact
with a thicker yellow soil above the bedrocks. Compared with Site A,
Site B has various vegetation types, mostly consisted of evergreen
broad-leaved forest and deciduous broad-leaved forest. The Site C
(25°5′9″N, 105°19′48″E) is located in a flat karst basin and mainly
outcrop rock is dolomitic limestone. As an experiment site in the
southwest of Guizhou, which has a humid and warm subtropical climate.
The soil around the experiment site is calcareous soil and zonal yellow
soil. Due to its suitable climate and soil conditions, the vegetation of
these areas is in good condition; most of them are evergreen
broad-leaved forest.
These three filed experiment sites are all the typical karst valley or
basin landform, and the prominent outcrops are carbonate rocks. The soil
and vegetation around these experiment sites are zonal soil and
vegetation in Southwest China. From Site A to Site C, the climatic
condition gradually changes from a dry and cold climate to a warm and
humid environment. The exogenous situation of karst dissolution in three
sites is distinct, and it can be regarded as a typical representative of
different karst topography in Southwest China.