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Scientific Journal of Earth Science June 2014, Volume 4, Issue 2, PP.55-66

Analysis of Dynamic Change Degree of Rock

Desertification in Lianjiang Watershed in

Northern Guangdong, China from 1988 to 2006 Mingchong Wang

1,2, Xizhi Wang

2#, Jun Wang

2,3, Zhaoxiong Liang

2, Zhou Chen

2,3, Xinchang Zhang

1

1. Institute of Geography Science and Planning, Sun Yat-Sen University, Guangdong Guangzhou 510275, China

2. Department of Resource and Environment, Foshan University, Guangdong Foshan 528000, China

3. School of Geography, South China Normal University, Guangdong Guangzhou 510631, China

# Corresponding author Email: wangxizhi71@163.com

Abstract

This article takes Karst-influenced Lianjiang Watershed in Northern Guangdong as the research object, the article have interpreted

non-karst district and karst district imagery respectively, and have constructed karst district and non-karst district classification

system. With GIS and landscape pattern theory, the typical Karst landscapes and spatial temporal dynamic of rock desertification

land change in Lianjiang Watershed were analyzed based on translated data from remote sensing images in 1988 and 2006. The

Lianjiang Watershed is divided into karst district and no-karst district based on it’s geological map. With practical situation in the

basin and the land use classification system, the no-karst district is divided into 9 types of landuse: cultivated land, garden plots,

forest land, shrubland, grass land, construction land, water area and unused land. According to development degree of rocky

desertification and whether it is occurred in the karst district or not, we divide the karst district into rocky desertification land and

non-desertification. The non-desertification is divided into 6 types of landuse: cultivated land, garden plots, forest land,

construction land, water area and potential of rocky desertification land. According as the theory of ecological datum plane, we

classified the rocky desertification lands into four grades as light, middle, serious, and extremely serious in the rocky

desertification land, graded each rocky desertification land with indexes which including rate of outcrops, form of karst

physiognomy, gradient of the earth's surface, thickness of soil, coverage degree of mantle rock, degree of soil erosion, coverage

rate of vegetation, plant and types of land use. The results indicate that: the area and the patch number of rock desertification

decreased respectively by 76.42 km2 and 27 584 blocks from 1988 to 2006. The main types of rock desertification have changed

from serious and medium of rocky desertification to the medium and light during the 18a. During the remote sensing monitoring

period, the light of rocky desertification land has obvious increasing trend, the area had been increased by 72.39 km2 . The

moderate, medium, serious and extremely serious of rocky desertification lands developed in the direction of reducing, their area

had been reduced by 39.51 km2, 104.99 km2 and 4.31 km2 respectively. All kinds of landscape index were calculated at class level

and landscape level. Quantitative analysis showed that the spatial pattern changes of rock desertification in Lianjiang Watershed

basin is different at degree. In details, the landscape heterogeneity and fragmentation all declined, while landscape dominance

increased. The Patch Richness Density (PRD) index is 0.0013, The Area-Weighted Mean Fractal Dimension Index (AWMPDF)

indexes are among l.0814 to l.4176, and is in the lower part of maximum range (1 to 2), the Landscape Shape Indexes (LSI)

indices are among 38.0000 to 409.1015, the Patch Density (PD) and Edge Density (ED) are very low, are among

0.1600entries/100ha-11.9723entries/100ha,and among 0.7480m/ha-137.0875m/ha. All these indices indicate the geometric shape

of various landscape patches are quite complicated, the intersected degree is low relatively, the fragmentation is not obvious, the

spatial heterogeneity is low, the overall diversity degree is not high and the richness is low.

Keywords: Karst District; Rock Desertification; Lianjiang Watershed; Landscape Pattern

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INTRODUCTION

Rocky desertification is a kind of land degradation in karst areas caused by human interventions, which is

demonstrated as destroyed vegetations, water and soil erosion, bared base rocks[1]

. The fractional cover of exposed

rock and vegetation are the main performance characteristics of the ground and also key indicators of desertification

to access desertification. Land degradation is a dynamic process which is a comprehensive reflection of various

surface coverage elements included vegetation, bedrock, soil and other land cover elements. The phenological

characteristics of vegetation, deciduous vegetation and its litter of no-photosynthetic capacity of vegetation cover,

soil cover, etc. They also has important characterizing rocky desertification information role. Rocky desertification

has already become a serious ecological problem worldwide and also a critical issue to be settled in the 21st

century[2-3]

. In southwest China, land rocky desertification is particularly grievous[4]

. The karst rock mountainous

areas in Northern Guangdong belongs to the eastern branch of the karst rock mountainous areas in Southwestern

China and it is one of the most important rock desertification area of the Southwestern China[5]

.

Landscape is an area with high spatial heterogeneity, which consists of interactive patches and certain laws.

Landscape dynamic changes, spatial pattern and process analysis are one of the cores in landscape ecological

studies[6-7]

, and landscape changes are the results as well as the demonstration of interaction between various internal

conflicts and external forces, which is the transformation process of landscape from one state to another[8-9]

. In the

Studies of Ecology, the river basin can be as a fairly ideal independent research unit. Now, the Study of river basin

involve Matter Circulation, Landscape Pattern Change, Soil and Water Conservation, Ecosystem Evaluation, and so

on[10-14]

. In order to find some regularity of karst rocky desertification occurrence and development, this paper

selectes Karst-influenced Lianjiang Watershed in Northern Guangdong and studies on the Karst rocky desertification

landscape. With GIS and landscape pattern theory, the typical Karst landscapes and spatial temporal dynamic of rock

desertification land change in Lianjiang Watershed were analyzed based on translated data from remote sensing

images in 1988 and 2006. Which will be of practical value and realistic meaning to the ecological management work

of the land rocky desertification.

1 GENERAL SITUATION OF THE STUDY AREA AND DATA SOURCES

1.1 General Situation of the Study Area

FIG.1 LOCATION OF LIANGJIANG RIVER BASIN

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Liangjiang River basin is the typical karst landform in Guangdong, which lies in the northwest of Guangdong

Province with the geographical location of 24°09′~25°07′N and 112°10′~113°18′E (Fig.1). The Lianjiang River is

the largest branch of the North River, which is known as small North River. The study area is located in the humid

monsoon area within the southern subtropical zone, and has an annual mean temperature of 19~20℃ and the highest

temperature in July, average up to 29℃. Average annual rainfall of the study area is 1 770mm, uneven distribution of

the year, mainly concentrated in from April to June. Terrain of the Lianjiang Watershed extended from the northwest

to the southeast. Mount Shikengkong in the the Watershed is the highest mountain of Guangdong Province, with the

altitude of 1 902m. Stream Network of Watershed has a pinnate distribution in space. The whole area of the

Watershed is 10 061km2. Terrain of limestone area is significantly in the Watershed, and limestone area accounts for

about 40% of the watershed area. The Karst Landforms such as karst cave, fracture and so on are developmented in

the limestone area. There ara many plant species in the study area, which mainly include coniferous forests,

evergreen broad-leaved forests, deciduous broad-leaved forest, coniferous and broad-leaved mixed forest, bamboo

forest, shrub forest, shrub-grassland. The Soil types mainly consists of red soil and limestone soil, which develops

from relics of carbonate rock dissolution[15-17]

.

1.2 Data Sources and Processing Method

1) Data Sources

Landsat TM data of December, 1988 and December, 2006, DEM data of Liangjiang River basin, all of their spatial

resolution are 30m. And other related datas, such as the geological map of Lianjiang Watershed, topographical map,

the investigation of forest fields and the investigation of rocky desertification, and so on.

2) Data Processing

Geometric rectification and projection transformation of the data was conducted in ENVI with the field survey and

relief map as references, and new samples were taken from the Landsat TM images with the pixel size of 30m×30m.

Extracting boundary of watershed based on DEM data with GIS software, and Remote Sensing image is cutted by

the boundary data for obtaining image of the watershed. GIS software is used to digitize geological map of the basin

for obtaining vectorization boundary of karst district and no-karst district in the Lianjiang Watershed, and the

boundary data is used to clipe the image of the watershed for obtaining Remote Sensing image of karst district and

image of no-karst district.

2 RESEARCH METHODS

2.1 Construction of Classification System and Data Processing

TABLE 1 THE CLASSIFICATION SYSTEM OF LAND USE/COVER IN THE STUDY AREA

first classes second classes third classes

karst district

rocky desertification

extremely serious rocky desertification serious rocky desertification

middle rocky desertification light rocky desertification

non-desertification

potential of rocky desertification cultivated land

garden plots forest land

construction land

water area

no-karst district

cultivated land

garden plots forest land

shrubland grass land

construction land

water area unused land

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The Lianjiang Watershed is divided into karst district and no-karst district based on it’s geological map. With

practical situation in the basin and the land use classification system, the no-karst district is divided into 8 types of

landuse: cultivated land, garden plots, forest land, shrubland, grass land, construction land, water area and unused

land. According to development degree of rocky desertification and whether it is occurred in the karst district or not,

we divide the karst district into rocky desertification land and non-desertification. The non-desertification is divided

into 6 types of landuse: cultivated land, garden plots, forest land, construction land, water area and potential of rocky

desertification land. According as the theory of ecological datum plane, we classified the rocky desertification lands

into four grades as light, middle, serious, and extremely serious in the rocky desertification land, graded each rocky

desertification land with indexes which including rate of outcrops, form of karst physiognomy, gradient of the earth'

s surface, thickness of soil, coverage degree of mantle rock, degree of soil erosion, coverage rate of vegetation, plant

and types of land use[18]

. Classification System is shown in Table 1.

2.2 Evaluation of Land Use/Cover Changes

At present, there are some mature methods about quantitative study on the pattern and process of land use/cover

changes based on remote sensing data[19]

. Two indexes of the degree of land use / cover change and the transition

matrix of land use/cover are used to reveal the basic characteristics and spatial pattern changes of land use/cover

change[20]

. The methods as follows:

(1) The degree of land use / cover change, the expression as follows:

ΔU=Ub-Ua (1)

In this expression, the number of some kind of land use/cover at the beginning and end of study period are denoted

by Ua and Ub, variable quality changes of land use/cover area is denoted by ΔU.

(2) The transition matrix of land use/cover, it’s the main methods of quantitative research of the number and

direction of Mutual Transformation of and use/cover types. The transition matrix of land use/cover is an actual

reflection of transfer direction among land use/cover types and Structure characteristics of land use change[21,22]

, and

it can quantitatively acquire the features of The degree of changes between different types.

2.3 Landscape Change Analysis

ArcMap9.0 and Fragstats 3.3 were respectively utilized to do statistic works and analyze landscape characteristics.

There are 19 indicators 6 classes in total, 7 indicators 2 classes are selected at class level, Area/Perimeter/Density

metrics: Total Class Area(CA), Percentage of Landscape(PLAND), Number of Patches(NP), Patch Density(PD),

Mean Patch Size(MPS), Edge Density (ED), Shape metrics: Landscape Shape Index (LSI), Area-Weighted Mean

Fractal Dimension Index(AWMPDF), 12 indicators 4 classes are selected at landscape level, Area/Perimeter/Density

metrics: Total Landscape Area(TA), Largest Patch Index (LPI), Number of Patches(NP), Patch Density(PD), Mean

Patch Size(MPS), Edge Density (ED), Shape metrics: Landscape Shape Index (LSI), Area-Weighted Mean Fractal

Dimension Index(AWMPDF), Contagion metrics: Contagion Index(CONTAG), Diversity metrics: Patch Richness

Density(PRD), Shannon's Diversity Index(SHDI), Simpson's Diversity Index(SIDI). As for calculation methods and

ecological implications of the above indexes, please refer to the instructions of FRAGSTATS3.3 and reference[23]

.

3 RESULTS AND ANALYSIS

3.1 Land-use Change in the Study is

According to the analysis of the three land-use maps in 1988 and 2006 (Fig.2), the area of the main land-use types

for the two-time period are potential of forest land, rocky desertification, cultivated land and shrubland, and the area

of the four types increases from 8 938.80 km2 in 1988 to 9 225.84 km

2 in 2006.The percentage of area increases

from 88.38% to 91.13%(Tables 2).

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1 cultivated land,2 garden plots,3 forest land,4 shrubland,5 grass land,6 construction land,7 water area,8 unused land, 9 potential of rocky desertification, 10 light

rocky desertification, 11 middle rocky desertification, 12 serious rocky desertification, 13 extremely serious rocky desertification

FIG.2 THE SPATIAL DISTRIBUTION OF LAND USE/COVER IN LIANGJIANG RIVER BASIN IN1988 AND 2006

TABLE2 LAND USE/COVER CHANGES IN LIANGJIANG RIVER BASIN IN 1988-2006

Type

1988 2006 1988-2006

Area

(km2)

Area

(%)

Area

(%)

Area

(%)

Area

(km2)

Area

(%)

Area

(%)

Area

(%)

Change

(km2)

karst d

istrict

rock

y

desertificatio

n

extremely serious rocky

desertification 8.19 2.29 0.21 0.08 3.88 1.38 0.10 0.04 -4.31

serious rocky desertification 157.15 43.87 3.97 1.55 52.16 18.51 1.32 0.52 -104.99

middle rocky desertification 149.65 41.78 3.78 1.48 110.14 39.09 2.78 1.09 -39.51

light rocky desertification 43.21 12.06 1.09 0.43 115.60 41.02 2.92 1.14 72.39

subtotals 358.20 100.00 9.05 3.54 281.78 100.00 7.11 2.78 -76.42

no

n-d

esertification

potential of rocky desertification 2700.21 74.98 68.19 26.70 2721.27 73.93 68.67 26.88 21.06

cultivated land 447.98 12.44 11.31 4.43 405.98 11.03 10.25 4.01 -42.00

garden plots 4.63 0.13 0.12 0.05 6.56 0.18 0.17 0.06 1.93

forest land 396.88 11.02 10.02 3.92 487.12 13.23 12.29 4.81 90.24

construction land 40.94 1.14 1.03 0.40 48.86 1.33 1.23 0.48 7.92

water area 10.73 0.30 0.27 0.11 11.09 0.30 0.28 0.11 0.36

subtotals 3601.37 100.00 90.95 35.61 3680.88 100.00 92.89 36.36 79.51

subtotals 3959.57 100.00 39.15 3962.66 100.00 39.15 3.09

no

-karst d

istrict

cultivated land 685.78 11.14 6.78 555.75 9.02 5.49 -130.03

garden plots 13.77 0.22 0.14 81.28 1.32 0.80 67.51

forest land 2881.05 46.81 28.49 3734.40 60.62 36.89 853.35

shrubland 1826.90 29.69 18.06 1321.32 21.45 13.05 -505.58

grass land 280.81 4.56 2.78 165.40 2.69 1.63 -115.41

construction land 136.60 2.22 1.35 203.93 3.31 2.01 67.33

water area 48.44 0.79 0.48 62.18 1.01 0.61 13.74

unused land 280.81 4.56 2.78 35.82 0.58 0.35 -244.99

subtotals 6154.16 100.00 60.85 6160.08 100.00 60.9 5.92

100.00 100.00

Land use has changed significantly over the whole period from 1988 to 2006 in Lianjiang River watershed. During

no

n-d

esertification

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the period from 1988 to 2006, the most dramatic change took place to forest land that has the highest increase area of

943.59 km2, and 28.79%, or garden plots at a rate of 377.39%, 69.44 km

2. Construction land, water area, potential of

rocky desertification land, and light rocky desertification land gained 75.25 km2, 14.10 km

2, 21.06 km

2, and 72.39

km2, or at a rate of 42.38%, 23.83%, 0.78%, and 167.53%, respectively. In contrast, cultivated land, shrubland, grass

land, unused land, middle rocky desertification land, serious rocky desertification land and extremely serious rocky

desertification land reduced by 172.03 km2, 505.58 km

2, 115.41 km

2, 244.99 km

2, 39.51 km

2, 104.99 km

2, and

4.31km2 at the same period, or at a rate of 15.17%,27.67 %,41.10 %,87.24 %,26.40 %,66.81 %, and 52.63%,

respectively. The area of rock desertification decreased respectively by 76.42 km2 from 358.2km

2 in 1988 to 281.78

km2 in 2006. The main types of rock desertification have changed from serious and medium of rocky desertification

to the medium and light during the 18a. During the remote sensing monitoring period, the light of rocky

desertification land has obvious increasing trend, the area had been increased by 72.39 km2. The moderate, medium,

serious and extremely serious of rocky desertification lands developed in the direction of reducing, their area had

been reduced by 39.51 km2, 104.99 km

2 and 4.31 km

2 respectively.

Note: (1 changes of other types, 2 no change of cultivated land, 3 cultivated land to construction land,4 no change of garden plots,5 no change of forest land,6 forest

land to shrubland,7 no change of shrubland,8 shrubland to forest land,9 no change of grass land,10 grass land to forest land,11 grass land to shrubland,12 no change

of construction land,13 no change of water area,14 no change of unused land,15 no change of potential of rocky desertification,16 potential of rocky desertification to forest land,17 light rocky desertification to potential of rocky desertification,18 middle rocky desertification to potential of rocky desertification,19 serious rocky

desertification to potential of rocky desertification)

FIG.3 THE MAIN CHANGES IN LAND USE/COVER IN LIANGJIANG RIVER BASIN FROM 1988 TO 2006

Space changes of land use/cover in the Lianjiang watershed in the monitoring period can be reflected in Figure 2.

Combining with elevation data and relevant information, the following conclusions can be found: cultivated land

appears decreasing tendency in the whole watershed; forest land was mainly distributed at higher elevation mountain

in no-karst distric and nature reserve; stray distribution of each grade rocky desertification land mainly in the middle

of Lianjiang basin, By comparison, the zones of decrease in area of rocky desertification are mainly distributed in the

village of Dongshan, town of Yanbei, town of Qinglian, town of Qingkeng and town of Xiaojiang and other places.

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TAB 3 THE TRANSITION MATRIX OF LAND USE/COVER IN LIANGJIANG RIVER

BASIN FROM 1988 TO 2006 (KM2, %)

Type cultivated

land

garden

plots

forest

land

shrub

land

grass

land

construc-

tion land

water

area

unused

land potential light middle serious

extremely

serious

1988

(%)

cultivated 534.58 22.24 47.30 182.83 6.67 106.97 8.91 7.39 213.98 7.06 5.09 0.29 0.15 11.31

garden plots 6.37 1.28 2.16 2.76 0.05 0.89 0.09 0.06 2.67 0.08 0.01 0.00 0.00 0.16

forest land 51.92 17.52 2581.28 331.09 36.66 7.42 6.11 2.67 248.40 4.05 3.91 1.77 0.16 32.57

shrubland 84.09 25.08 1059.31 577.12 49.61 12.54 6.04 9.28 5.46 0.15 0.09 0.04 0.01 18.09

grass land 6.13 0.75 137.60 63.23 58.76 0.44 0.77 0.64 0.29 0.04 0.04 0.01 0.00 2.66

construction 42.80 2.17 5.93 28.12 0.12 65.84 8.01 1.50 18.51 0.00 0.23 0.02 0.04 1.71

water area 3.34 0.32 2.37 6.30 0.06 7.25 36.14 0.46 3.64 0.01 0.10 0.04 0.06 0.59

unused land 50.37 3.42 40.49 127.90 4.42 27.34 3.68 9.66 1.15 0.01 0.04 0.00 0.00 2.66

potential 161.40 4.06 330.65 3.82 0.28 18.94 3.34 0.05 2005.21 85.25 50.93 33.75 1.78 26.70

light 2.14 0.01 3.83 0.03 0.01 0.14 0.02 0.00 30.24 2.93 3.47 0.35 0.03 0.43

middle 22.03 0.05 3.84 0.15 0.05 1.38 0.11 0.01 95.01 6.97 17.70 1.48 0.78 1.48

serious 2.10 0.01 18.13 0.16 0.02 0.66 0.01 0.00 103.44 1.23 20.67 9.85 0.67 1.55

extremely 0.18 0.00 0.85 0.00 0.00 0.00 0.00 0.00 4.48 0.20 1.83 0.54 0.10 0.08

2006(%) 9.57 0.76 41.88 13.09 1.55 2.47 0.72 0.31 27.03 1.07 1.03 0.48 0.04 100.00

3.2 Analysis on Temporal and Spatial Variation of Land Use/Cover

1) Analysis on the Transition Matrix of Land Use/Cover in Liangjiang River Basin

Change map of 2 periods were obtained by carrying out logical operations in the spatial analysis module of ArcMap

9.0 (Fig.3). It could be known from the map that landscape changed most dramatically during 1988 and 2006.We

may draw such conclusions from Fig.3 and Tab 3 as follows: The no-change area of cultivated land is 534.58 km2,

and it’s total area decreased 1.74%, the lost of cultivated land was mainly changed into construction land, with

106.97km2, other potential of rocky desertification land and shrubland. The area of garden plots increased 0.60%, the

increased area mainly come from shrubland and cultivated land. The no-change area of forest land is 2581.25 km2,

increased 9.31%, the change mainly come from shrubland and potential of rocky desertification land. Area of

shrubland decreased 5.00%, the lost area mainly changed into forest land. Area of grass land decreased 1.11%, the

lost area mainly changed into forest land and shrubland. The area of cultivated land increased 0.76%, the increased

area mainly come from cultivated land, unused land and potential of rocky desertification land. Area of water area

increased 14.14 km2, the area mainly changed from cultivated land, forest land, construction land and shrubland. The

area of unused land decreased 2.32%, the lost area mainly changed into shrubland, forest land and cultivated land.

The no-change area of potential of rocky desertification land is 2005.21km2, little change in the total area, but

reciprocal transformation of rocky desertification between grades was obvious. The no-change area of other grades

of rocky desertification is small, and all is in the range of 12%, which reflects the stabilities of other grades of rocky

desertification is worse.

We may draw such conclusions from Fig.3 and Tab 3 as follows: The lost of cultivated land was mainly changed into

construction land, with 106.97 km2. The extent of unused land reduced extremely to 87.24% , it was mainly changed

into cultivated land with 50.37 km2, forest land with 40.49 km

2, shrubland with 127.9 km

2 and construction land with

27.34 km2. The lost of extremely serious rocky desertification land, serious rocky desertification land and middle

rocky desertification land, was mainly changed into potential of rocky desertification land with 4.48 km2 (54.77%),

103.44 km2 (65.91%) and 95.01 km

2 (63.53%), respectively.

2) Analysis on the Transition Matrix of Land Use/Cover in No-karst Distric

We may draw such conclusions from Tab 4 as follows: The no-change area of cultivated land in no-karst distric in

Liangjiang River basin is 333.67 km2, and it’s total area decreased 2.17%, the lost of cultivated land was mainly

changed into shrubland and construction land. The area of garden plots occupies proportion of the total area of the

no-karst distric has slightly increased, the change mainly comes from cultivated land and shrubland. The no-change

area of forest land is 2449.80 km2, increased 13.71%, the change mainly come from shrubland and grass land. The

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area of cultivated land increased 1.05%, the increased area mainly come from cultivated land and unused land. Area

of water area increased, which mainly changed from cultivated land and construction land. The area of unused land

decreased, which changed into cultivated land and shrubland.

TAB 4 THE TRANSITION MATRIX OF LAND USE/COVER IN NON-KARST DISTRICT OF LIANGJIANG RIVER

BASIN FROM 1988 TO 2006 (KM2,%)

Type cultivated

land

garden

plots

forest

land

Shrub

land

grass

land

construction

land

water

area

unused

land

1988

(%)

cultivated land 333.67 20.00 44.02 182.06 6.63 91.6 7.65 7.37 11.27

garden plots 5.17 1.17 1.72 2.75 0.05 0.77 0.08 0.06 0.19

forest land 44.36 17.30 2449.81 331.04 36.65 6.94 5.98 2.67 47.09

shrubland 83.83 25.09 1059.34 577.70 49.65 12.52 6.04 9.28 29.66

grass land 6.10 0.75 137.61 63.29 58.81 0.44 0.77 0.64 4.37

construction land 33.29 5.77 5.82 28.03 0.12 54.28 7.09 1.50 2.21

water area 2.53 0.31 2.31 6.30 0.06 6.46 30.83 0.46 0.80

unused land 50.17 3.43 40.49 128.02 4.43 27.30 6.80 9.66 4.40

2006(%) 9.10 1.20 60.8 21.46 2.54 3.26 1.06 0.51 100.00

TAB 5 THE TRANSITION MATRIX OF LAND USE/ COVER IN KARST DISTRICT OF LIANGJIANG RIVER

BASIN FROM 1988 TO 2006 (KM2, %)

Type cultivated

land

garden

plots

forest

land

construction

land

water

area potential light middle serious

extremely

serious

1988

(%)

cultivated land 198.74 2.2 3.18 14.95 1.23 212.55 7.05 5.09 0.29 0.15 11.29

garden plots 1.19 0.10 0.43 0.11 0.01 2.66 0.08 0.01 0 0 0.12

forest land 7.43 0.22 130.85 0.48 0.12 246.37 4.04 3.88 1.72 0.15 10.02

construction 9.34 0.08 0.12 11.23 0.98 18.42 0 0.23 0.02 0.04 1.03

water area 0.80 0.01 0.06 0.77 5.17 3.60 0.01 0.10 0.04 0.06 0.27

potential 160.59 3.85 326.65 18.67 3.26 2007.04 85.33 50.97 33.79 1.78 68.22

light 2.14 0.01 3.80 0.14 0.02 30.27 2.94 3.47 0.35 0.03 1.09

middle 22.02 0.05 3.81 1.37 0.10 95.09 6.97 17.72 1.48 0.78 3.79

serious 2.10 0.01 17.98 0.65 0.08 103.53 1.23 20.69 9.86 0.67 3.97

extremely serious 0.18 0 0.85 0 0 4.48 0.20 1.83 0.54 0.10 0.21

2006(%) 10.25 0.17 12.36 1.23 0.28 69.04 2.73 2.64 1.22 0.10 100.00

3) Analysis on the Transition Matrix of Land Use/Cover in Karst Distric

We may draw such conclusions from Tab 5 as follows: The no-change area of cultivated land in karst distric in

Liangjiang River basin is 198.74 km2,and it’s total area decreased 1.04%, the lost of cultivated land was mainly

changed into potential of rocky desertification land. The area of garden plots, construction land and water area

slightly increased, the change mainly comes from cultivated land and potential of rocky desertification land. The of

forest land increased 2.34%, the change mainly come from potential of rocky desertification land. The area of middle

rocky desertification land decreased, which changed into potential of rocky desertification land. The area of

extremely serious and serious rocky desertification land were decreased, which changed into potential of rocky

desertification land.

3.3 Analysis of Landscape Pattern Change

1) Pattern Changes at the Class Level

The total areas of all landscape types and area ratios in different periods demonstrated that forest land and potential

of rocky desertification land took up a dominant status in the study area (Table 6).

Landscape characteristics had changed slightly and only the areas of landscape types had fluctuated with time, which

were mainly demonstrated as the increasing area of forest land, construction land, garden plots, water area and light

and potential of rocky desertification, decreasing area of shrubland, grass land, unused land, cultivated land and

extremely serious, serious and middle rocky desertification. Among which, the area of construction land during 1988

and 2006 had been increased 75.25 km2,and 42.38%, cultivated land decreased 172.03 km

2,and 15.17%, unused land

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decreased 244.99 km2,and 87.24%,which indicated that construction land took up part of the cultivated land due to

the increasing population, and meanwhile, the area of unused land decreased greatly. Area of extremely serious,

serious and middle rocky desertification land during 1988 and 2006 had been decreased greatly by 52.63%, 66.81%

and 26.40%, and meanwhile, area of light rocky desertification land increased as much as 2 times than the original

one, which indicated that the overall landscape of rocky desertification land was obviously renewed and improved.

The total area of rocky desertification decreased 76.42 km2, and 21.33%, and meanwhile, area of forest land, garden

plots and water area increased by 943.59 km2

(28.79%), 69.44 km2

(as much as 4 times than the original one),and

14.10 km2 (23.83%), thus ecological restoration of the overall landscape in Liangjiang River basin of was obviously.

TAB 6 INDICES COMPARISON AT CLASS-LEVEL IN THE STUDY AREA FROM 1988 TO 2006

Type

1988 2006

CA PLAN

D NP PD ED

AWMP

DF LSI CA

PLAN

D NP PD ED

AWMP

DF LSI

karst d

istrict ro

cky

desertificatio

n

ESR

D 819.3600 0.2069 2790 0.7046 1.8974 1.0814 65.8953 388.2600 0.0980 1024 0.2584 0.7480 1.0947 38.0000

SRD 15715.0800 3.9689 28147 7.1086 29.2170 1.1293 232.5837 5216.6700 1.3165 14648 3.6965 11.0720 1.1015 152.7427

MRD 14965.6500 3.7796 22781 5.7534 24.7159 1.1450 201.4473 11013.7500 2.7794 21300 5.3752 19.8955 1.1276 189.3057

LRD 4321.5300 1.0914 12102 3.0564 9.3466 1.0926 141.3098 11560.3200 2.9173 21153 5.3381 19.9330 1.1371 185.0349

no- d

esertification

PORD

270022.5900 68.1948 14578 3.6817 137.0875 1.4176 273.2872 272126.7000 68.6725 11405 2.8781 119.1406 1.3890 239.0359

CL 44797.0500 11.3136 28167 7.1136 43.6033 1.2198 211.7188 40598.0100 10.2451 16793 4.2378 37.2776 1.2046 189.8609

GP 463.2300 0.1170 2557 0.6458 1.1476 1.0554 53.8403 656.2800 0.1656 1432 0.3614 1.1928 1.0908 46.8596

FL 39686.9400 10.0230 45812 11.5699 55.8202 1.1824 283.6817 48712.2300 12.2928 21925 5.5329 48.8850 1.2018 225.6929

CTL 4093.4700 1.0338 8751 2.2101 6.8638 1.1360 110.6347 4886.0100 1.2330 5031 1.2696 6.5482 1.1451 96.7639

WA 1073.0700 0.2710 1435 0.3624 1.3761 1.1307 43.4155 1109.2500 0.2799 634 0.1600 1.0709 1.1509 33.8430

no-k

arst district

CL 68559.6600 11.1409 26889 4.3694 34.5405 1.2853 209.7772 55561.7700 9.0196 30783 4.9972 33.7795 1.2304 227.0394

GP 1377.9000 0.2239 4275 0.6947 1.7121 1.0943 71.0887 8132.4900 1.3202 24655 4.0024 10.2049 1.1017 176.3389

FL 288060.0300 46.8094 41072 6.6741 84.6826 1.3572 248.7603 373400.7300 60.6160 19605 3.1826 62.7463 1.3435 166.6760

SL 182745.7200 29.6959 73676 11.9723 110.1559 1.2997 407.0628 132201.7200 21.4610 66907 10.8614 94.2426 1.2632 409.1015

GL 28068.0300 4.5610 35947 5.8413 22.1007 1.2045 207.2856 16528.2300 2.6831 25896 4.2038 14.2736 1.1645 174.0653

CTL 13654.2600 2.2188 21180 3.4417 13.6326 1.1801 181.8244 20385.9000 3.3093 21557 3.4995 16.7001 1.2278 183.8330

WA 4841.2800 0.7867 2899 0.4711 2.5609 1.2381 57.9289 6214.8600 1.0089 3776 0.6130 3.0608 1.2432 61.2605

UL 28082.7900 4.5634 43873 7.1293 29.2354 1.1846 273.8623 3583.9800 0.5818 8950 1.4529 3.8359 1.1374 99.6200

Note: ESRD refers to extremely serious rocky desertification, SRD refers to serious rocky desertification, MRD refers to middle rocky desertification, LRD refers

to light rocky desertification, PORD refers to potential of rocky desertification, CL refers to cultivated land, GP refers to garden plots, FL refers to forest land, SL

refers to shrubland, GL refers to grass land, CTL refers to construction land, WA refers to water area, UL refers to unused land.

Among Number of Patches (NP), that of forest land was the greatest and followed by that of shrub land and

cultivated land in1988, and shrub land followed by cultivated and land forest land. Through comprehensively

analyzing the areas and area ratios, it could be known that shrub land and cultivated land were more scattered than

forest land. As for Landscape Shape Index (LSI), that of shrub land was the highest and followed by that of forest

land, cultivated land and potential of rocky desertification land, which was caused by irregular land uses in the study

area with karst landforms, numerous mountainous areas and low-lying lands. LSI of extremely serious rocky

desertification land and water area was lower due to their small patch areas and scattered distributions. As for Patch

Density (PD), that of forest land was the highest and followed by that of shrub land and cultivated land, and

meanwhile, that of extremely serious rocky desertification land and water area was the lowest, which indicated that

extremely serious rocky desertification land and water area with smaller areas were distributed into the dominant

base of shrub land and cultivated land.

The Area-Weighted Mean Fractal Dimension Index (AWMPDF) indexes are among l.0814 to l.4176, and is in the

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lower part of maximum range(1 to 2), the Landscape Shape Indexes (LSI) indices are among 38.0000 to 409.1015,

the Patch Density (PD) and Edge Density (ED) are very low, are among 0.1600entries/100ha-11.9723entries/100ha,

and among 0.7480 m/ha-137.0875 m/ha.

2) Pattern Changes at the Landscape Level

In the landscape analysis software—Fragstats3.3, pattern indices of the study area at the landscape level in different

periods were calculated (Table 7). Mean Patch Size (MPS) was used to indicate the aggregation or fragmentation

degree of different landscapes, and the higher the value, the more aggregated the landscape. Within the study periods,

the values have not changed much and that in 1988 was 3.3922, 4.9408 in 2006. The economic growth during the

18a had brought more serious human interventions and led to relatively greater landscape changes.

TAB 7 INDICES COMPARISON AT LANDSCAPE-LEVEL IN THE STUDY AREA FROM 1988 TO 2006

Year/type TA NP PD ED LSI LPI MPS AWMPDF CONTAG SHDI SIDI PRD

1988 1011248.2800 298108 29.4792 144.8837 366.5025 8.6029 3.3922 1.3280 50.9155 1.7333 0.7749 0.0013

2006 1012069.2600 204838 20.2395 117.9559 298.9512 11.7357 4.9408 1.3165 56.2588 1.5796 0.7240 0.0013

1988K 395957.9700 167120 42.2065 155.5377 260.8208 21.9713 2.3693 1.3416 59.3168 1.1233 0.5089 0.0010

2006K 396267.4800 115345 29.1079 132.8818 225.3090 17.0214 3.4355 1.3242 61.5216 1.0969 0.5008 0.0010

1988FK 615389.6700 249811 40.5940 149.3103 307.7172 11.7151 2.4634 1.3118 49.1881 1.3784 0.6756 0.0008

2006FK 616009.6800 202129 32.8126 119.4218 249.2083 18.0087 3.0476 1.3020 56.8039 1.1940 0.5763 0.0008

Area-Weighted Mean Fractal Dimension Index (AWMPDF) is mainly applied to describe the shape complexity of

patch edges at a certain scale, and the lower the value, the more regular the patch shape, and the more intervened the

patch. From 1988 to 2006, the AWMPDF of the study area had decreased, which indicated that the human

intervention to patches had increased with the economic growth, thus the patch shapes had simplified.

Contagion index (CONTAG) demonstrates the aggregation degree of different landscape components, a higher value

indicates that the landscape consists of a few aggregated large patches, and a lower value means that the landscape

consists of many scattered small patches. From 1988 to 2006, the landscape contagion indices of the study area were

moderate (Table 7), but increased slowly, which indicated the coexistence of a few aggregated large patches (mainly

are forest land and potential of rocky desertification land) and many scattered small patches (mainly are unused land,

extremely serious and serious rocky desertification lands), but a low aggregation degree; and within the study period,

contagion indices had been showing a trend of increase, which implied that the dominant degree of these large

patches had increased. Landscape diversity indexes demonstrate differences between the quantity of landscape

components and their ratios, and a higher value indicates a more evenly distributed landscape component. Within the

study period, landscape diversity indexes had decreased (Table 7), which implied that differences among ratios of

landscape components had increased.

4 CONCLUSIONS

This article takes Karst-influenced Lianjiang Watershed in Northern Guangdong as the research object, the article

have interpreted non-karst district and karst district imagery respectively, and have constructed karst district and

non-karst district classification system. According to development degree of rocky desertification and whether it is

occurred in the karst district or not, we divide the karst district into rocky desertification land and non-desertification.

According as the theory of ecological datum plane, we classified the rocky desertification lands into four grades as

light, middle, serious, and extremely serious in the rocky desertification land, graded each rocky desertification land

with indexes which including rate of outcrops, form of karst physiognomy, gradient of the earth's surface, thickness

of soil, coverage degree of mantle rock, degree of soil erosion, coverage rate of vegetation, plant and types of land

use.

The results indicate that: (1) the area and the patch number of rock desertification decreased respectively by 76.42

km2 and 27 584 blocks from 1988 to 2006. The main types of rock desertification have changed from serious and

medium of rocky desertification to the medium and light during the 18a. During the remote sensing monitoring

period, the light of rocky desertification land has obvious increasing trend, the area had been increased by 72.39km2.

(2) The medium, serious and extremely serious of rocky desertification lands developed in the direction of reducing,

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their area had been reduced by 39.51 km2, 104.99 km

2 and 4.31 km

2 respectively, and the lost area mainly changed

into potential of rocky desertification land. Which accord with the monitoring report on the rocky desertification in

karst regions in Guangdong province 2005. (3) All kinds of landscape index were calculated at class level and

landscape level. Quantitative analysis showed that the spatial pattern change of rock desertification in Lianjiang

Watershed basin is different at degree. In details, the landscape heterogeneity and fragmentation all declined, while

landscape dominance increased. The Patch Richness Density (PRD) index is 0.0013, The Area-Weighted Mean

Fractal Dimension Index (AWMPDF) indexes are among l.0814 to l.4176, and is in the lower part of maximum

range (1 to 2) , the Landscape Shape Indexes (LSI) indices are among 38.0000 to 409.1015, the Patch Density (PD)

and Edge Density (ED) are very low, are among 0.1600 entries/100ha-11.9723 entries/100ha, and among 0.7480

m/ha-137.0875 m/ha. All these indices indicate the geometric shape of various landscape patches are quite

complicated, the intersected degree is low relatively, the fragmentation is not obvious, the spatial heterogeneity is

low, the overall diversity degree is not high and the richness is low. The change of all Metrics in this paper from

1988 to 2006 indicates that the landscape pattern in Lianjiang Watershed have optimized.

ACKNOWLEDGMENT

In this paper, the research was sponsored by the National Natural Science Foundation of China, No. 31070426.

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AUTHOR

Mingchong WANG (1980- ), Specialized in Environmental Remote Sensing and GIS application. Email: wangmc@126.com