4.3 Response of karst dissolution to drought in different areas
A striking result of the study is that the drought losses of karst
dissolution of Site C were sharply lower than Site A and Site B except
for cropland. However, in terms of the proportion of losses, the drought
losses of Site C are not as small as seems (Table 2). Small karst
dissolution loss in Site C may be directly related to the lower natural
karst dissolution of Site C. It has long been assumed that the wetter
and warmer the area is, the higher the karst dissolution should be.
However, the karst dissolution in Site C with wetter and warmer
conditions is less than that in Site A and Site B. More than that, the
karst dissolution loss of cropland in Site A and Site B is the smallest,
while that in Site C cropland becomes the most loss of land cover type.
According to the climate data recorded at Anlong station, which nearly
by Site C (Table 5), during the experiment period, there is no severe
drought occurred in Site C. Within experiment time, there was only a
slight increase in precipitation, while the temperature increased by one
℃. Simultaneously, the largest continuous rainless days are 12 days, and
even the largest continuous no effective precipitation days are only 21
days. In other words, during the study period, the climate of Site C has
not changed abnormally. So, climate change should not be the main factor
of the lower karst dissolution loss for Site C.
Besides, we analyzed the soil environment carefully, and we found that
the soil pH value of Site C was lower than that of other regions in
total (Tables 4). Furthermore, except for the slightly higher soil
organic matter in Site C, there is not much difference in the three
sites (Tables 4). According to our data, it is difficult to determine
the reason for the lower karst dissolution of Site C. Of course, in
other studies, there are also cases where the dissolution environment is
pleasant, but the karst dissolution is not as high as expected (Yuan &
Cai, 1988). These results suggest that the karst dissolution results
from the combined effect of geology, soil, climate, and vegetation.
Additionally, it may also relate to the specific experiment site and
time.