Ecological Features in Karst Peak-cluster
Mountains in Nongla, Guangxi

By Dr.JIANG Zhongcheng

1. Karst landforms and geological settings in Nongla

Nongla is a village in the center of Guangxi Autonomous Region(Fig.1), about 2 km2 . The landform is a typical peak-cluster karst (Fengcong), with many steep peaks and two deep closed depressions. The highest peak is more than 700 m a.s.l., and the lowest point of the depression is about 400 m a.s.l.. Sinkholes and and underground karst conduits are drainage courses of water. Some small epikarst springs developed on the hillside of the peaks(Fig.2).

Fig. 2 Geomorphological section of Nongla area

The outcrop of rocks is mainly dolomite of the Donggangling Group of Devonia. But the dolomite is unpure, with some argillaceous and silicaeous component part, which leads to a special karst geological background, with relative abundant background value of trace elements in rocks. With element migration, results in the relative high mineral nutritious elements in karst waters and soils(Table 1 and 2).

Table 1 Chemical composition(%) of rock and soil in Nongla

 

SiO2

Al2O3

Fe2O3

P2O5

CaO

MgO

K2O

Na2O

Zn

Mn

Cu

Co

Rock

0.43

0.11

0.44

0.66

31.42

20.40

0.06

0.014

0.012

0.113

0.012

0.002

Soil

37.89

25.25

10.09

0.13

1.98

1.66

0.90

0.227

0.021

0.113

0.004

0.001

Table 2 Ionic Content (%) of spring water in Nongla

Ion

Ca

Mg

K

Na

Si

P

Fe

Al

Mn

Zn

Co

Cu

Content

63.74

13.12

0.26

0.55

0.53

0.07

0.2

0.2

0.004

0.002

0.02

0.001

 

2. Processes of rehabilitation of karst rock desert

In 1950s, like other karst areas in south China, all trees in Nongla were cut, resulting in serious rock desertification, which made the local people very difficult to survive due to lack water, soil, match and food. Since1963, local people have closed most peak passes and planted trees. Up to 1980s, some forests formed and water of some karst springs could flow for all seasons. After that time, some fruit trees such as oriange, persimmon, longan, peach, pomegranate and so on, herbs like kudingcha and japonica, and bamboo were planted in different environments. Today there are not only dense forests on some peaks(Photo 1), but also a lot of trees or crops around houses(Photo 2). And by looking for a good way to harness the fragile environments and making full use of the land resources, the local people have taken off their poverty and built a better life canditions.

Photo 1 Dense forest on the karst peak in Nongla

Photo 2 Green vegetation and crops surrounding house in Nongla

 

3.Distribution of Vegetation in the peak-cluster of Nongla

The farmers in Nongla village have developed a stereo ecological agriculture by planting a lot of local precious herbs , well-adjusted fruits and crops in different geomorphologic positions and karst geological backgrounds.

On steep peaks, they develop forests for keeping a permanend water resources from karst springs. On hillsides of the peak, they cultivate precious herbs and fruit trees, the main resources for get much money . The farmland is just on the bottom of the depressions, about 50 mu area, in which the local people mainly plant corn and hangou (a special taro growing in arid environments)(Fig 3).

Fig.3 Plane map of ecological features in Nongla

 

4. Special ecological features of Vegetation in Nongla

The special element migration law in fengcong stone mountains results in the karst geological ecology. The vegetation is characterized by lithophyte(Photo 3), calciphile, and xerophyte. And the species is diverse and quite different in different geological regions. The more wonderful thing is that, there are 270 kinds of herbs in Nongla Villige, and most of them are precious, such as fordii, pentaphyllum, rutaeocarpa, erubescens, rhynchophylla, kudingcha, japonica, etc.. Kudingcha (Photo 4)and japonica can be used as not only medicine but also drinking materials. Therefore, They are main economic plants to be cultivated in Nongla Village.

Photo 3 Tree grows in rocks

Photo 4 Kudingcha in Nongla

 


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