1 Introduction
Karst dissolution is one of the most fundamental issues in understanding
the formation and evolution of karst topography (Ren & Liu, 1983; Dixon
et al., 2001; Phillips, 2005; Ford & Williams, 2007). At the same time,
the karst dissolution process is also
an essential part of the global
carbon cycle, which plays a pivotal role in global carbon balance and
carbon sink estimation (Yuan, 1995; Gombert, 2002; Goudie, & Viles,
2012; Zeng, Liu, & Kaufmann, 2019). The key to solving all these
problems is to obtain a more realistic amount of karst dissolution.
Understanding and quantifying the influence of different factors on the
karst dissolution is the basis of obtaining a proper amount of karst
dissolution. Among these factors, the effect of drought on karst
dissolution is an important factor that cannot be ignored, especially in
global climate change. Observation results indicated that the drought is
one of the most frequent natural disasters worldwide (Qiu, 2010; Dai,
2013; Trenberth et al., 2014; Naumann et al., 2018), which has a
substantial impact on social economy and the natural environment. Tens
of thousands of studies have shown that droughts are becoming more
frequent and severe with climate warming (Easterling et al., 2000; IPCC,
2014; Sherwood, & Fu, 2014). Therefore, investigating the drought loss
of karst dissolution has become particularly urgent and vital for karst
research.
The essential characteristic of drought is the deficiency of
precipitation, which is the key to the karst dissolution. Some previous
studies have observed the effects of droughts on the karst dissolution,
mainly caused by precipitation reduction. For example, Zhang (2010) and
Wang et al. (2007) found that the karst dissolution in the dry season
and rainy season have a noticeable difference. Li et al. (2012) and Lan
et al. (2013) also found that the karst dissolution has a more or less
decline in the dry season. Nevertheless, the specific amount of karst
dissolution loss caused by drought has not been examined in detail,
particularly the karst dissolution loss caused by different intensity
droughts.
Many methods have developed for karst dissolution estimates and
measurements over the past decades (Yuan & Cai, 1988; Plan, 2005; Ford
& Williams, 2007; Gabrovšek, 2009; Moses, Robinson, & Barlow, 2014;
Kirstein et al., 2016; Pardo-Igúzquiza, Dowd, & Telbisz, 2020). More
popular methods to estimate and measure the karst dissolution are (1)
Calculation of solutional denudation by a formula; (2) Weight loss
measurement using standard tablets; (3) Short-term lowering of limestone
surfaces determined by micrometric measurements; (4) Long-term lowering
of bare-rock surfaces determined by measurement of surface
irregularities; and (5) Cosmogenic chlorine-36 measurements. Each method
has its advantages and disadvantages (Ford & Williams, 2007; Gabrovšek,
2009; Liu, 2011; Wang, Zhang, & Qin, 2013), and it might be suitable
for different situations. Among these approaches, weight loss
measurement using standard carbonate tablets is one of the simplest and
most effective ways of estimating the karst dissolution under various
environmental conditions (Yuan & Cai, 1988; Dixon et al., 2001; Plan,
2005). This method is not only the most direct way, but also can be
compared with each other, and is widely used in karst research (Yuan &
Cai, 1988; Dixon et al., 2001; Plan, 2005; Zhang, 2010; Hattanji et al.,
2014; Krklec et al., 2016).
The karst regions of Southwest China are the most developed karst
topography areas, including almost all types of karst landforms in the
world. Southwest China has approximately 5.1×105 km2of karst areas in exposed or outcropped carbonate rock (Jiang, Lian, &
Qin, 2014). It is about 5.8% of the total land and is distributed
mainly in Guizhou and surrounding areas. This area is also a typical
ecologically fragile area facing severe ecological and environmental
problems (Cai, 1996; Yuan, 1997; Wang, Liu, & Zhang, 2004; Jiang, Lian,
& Qin, 2014). Because of the particularity of the geological
environment and climatic conditions of Southwest China karst regions,
karstification is very strong and highly sensitive to changes in the
external environment, especially the changes in climate conditions.
Unfortunately, drought is also one of the most common natural disasters
in central Southwest China (Chen, & Zhai, 2014; Han et al., 2016),
known as ”Nine droughts in ten years.” Moreover, droughts in this area
have an apparent upward trend in recent years (Lin et al., 2015; Liu et
al., 2016). As a result, it is of great significance to study the effect
of drought on karst dissolution in central Southwest China.
The present study is a first attempt to quantifying the loss impact of
drought on karst dissolution and associated impact mechanism using
standard carbonate tablets in a field comparative control experiment.
This study focuses mainly on the amount of karst dissolution loss caused
by different intensity droughts in various areas of central Southwest
China. This information is crucial to the study of karst topography,
protection of the karst landscape, and the karst carbon balance
estimation. At the same time, we will discuss the impact mechanism of
drought on karst dissolution loss, which could shed light on studying
the karst process in the future.