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 - 55 http://www.j-es.org
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 - 56 http://www.j-es.org
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 rocky desertification
karst district non-desertification
no-karst district
third classes extremely serious rocky desertification serious rocky desertification middle rocky desertification light rocky desertification potential of rocky desertification cultivated land garden plots forest land construction land water area cultivated land garden plots forest land shrubland grass land construction land water area unused land
- 57 http://www.j-es.org
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 km2 in 2006.The percentage of area increases from 88.38% to 91.13%(Tables 2). - 58 http://www.j-es.org
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 rocky desertification non-desertification
karst district
no-karst district
extremely serious rocky desertification serious rocky desertification middle rocky desertification light rocky desertification subtotals potential of rocky desertification cultivated land garden plots forest land construction land water area subtotals subtotals cultivated land garden plots forest land shrubland grass land construction land water area unused land subtotals
Area (km2)
1988 Area Area (%) (%)
Area (%)
Area (km2)
2006 Area Area (%) (%)
Area (%)
1988-2006 Change (km2)
8.19
2.29
0.21
0.08
3.88
1.38
0.10
0.04
-4.31
157.15 149.65 43.21 358.20 2700.21 447.98 4.63 396.88 40.94 10.73 3601.37 3959.57 685.78 13.77 2881.05 1826.90 280.81 136.60 48.44 280.81 6154.16
43.87 41.78 12.06 100.00 74.98 12.44 0.13 11.02 1.14 0.30 100.00
3.97 3.78 1.09 9.05 68.19 11.31 0.12 10.02 1.03 0.27 90.95 100.00 11.14 0.22 46.81 29.69 4.56 2.22 0.79 4.56 100.00
1.55 1.48 0.43 3.54 26.70 4.43 0.05 3.92 0.40 0.11 35.61 39.15 6.78 0.14 28.49 18.06 2.78 1.35 0.48 2.78 60.85
52.16 110.14 115.60 281.78 2721.27 405.98 6.56 487.12 48.86 11.09 3680.88 3962.66 555.75 81.28 3734.40 1321.32 165.40 203.93 62.18 35.82 6160.08
18.51 39.09 41.02 100.00 73.93 11.03 0.18 13.23 1.33 0.30 100.00
1.32 2.78 2.92 7.11 68.67 10.25 0.17 12.29 1.23 0.28 92.89 100.00 9.02 1.32 60.62 21.45 2.69 3.31 1.01 0.58 100.00
0.52 1.09 1.14 2.78 26.88 4.01 0.06 4.81 0.48 0.11 36.36 39.15 5.49 0.80 36.89 13.05 1.63 2.01 0.61 0.35 60.9
-104.99 -39.51 72.39 -76.42 21.06 -42.00 1.93 90.24 7.92 0.36 79.51 3.09 -130.03 67.51 853.35 -505.58 -115.41 67.33 13.74 -244.99 5.92
100.00
100.00
Land use has changed significantly over the whole period from 1988 to 2006 in Lianjiang River watershed. During - 59 http://www.j-es.org
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 km2. Construction land, water area, potential of rocky desertification land, and light rocky desertification land gained 75.25 km2, 14.10 km2, 21.06 km2, 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 km2, 115.41 km2, 244.99 km2, 39.51 km2, 104.99 km2, 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 358.2km2 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 km2 and 4.31 km2 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. - 60 http://www.j-es.org
TAB 3 THE TRANSITION MATRIX OF LAND USE/COVER IN LIANGJIANG RIVER BASIN FROM 1988 TO 2006 (KM2, %) Type cultivated garden plots forest land shrubland grass land construction water area unused land potential light middle serious extremely 2006(%)
cultivated land 534.58 6.37 51.92 84.09 6.13 42.80 3.34 50.37 161.40 2.14 22.03 2.10 0.18 9.57
garden plots 22.24 1.28 17.52 25.08 0.75 2.17 0.32 3.42 4.06 0.01 0.05 0.01 0.00 0.76
forest land 47.30 2.16 2581.28 1059.31 137.60 5.93 2.37 40.49 330.65 3.83 3.84 18.13 0.85 41.88
shrub land 182.83 2.76 331.09 577.12 63.23 28.12 6.30 127.90 3.82 0.03 0.15 0.16 0.00 13.09
grass construc- water unused potential light middle land tion land area land 6.67 106.97 8.91 7.39 213.98 7.06 5.09 0.05 0.89 0.09 0.06 2.67 0.08 0.01 36.66 7.42 6.11 2.67 248.40 4.05 3.91 49.61 12.54 6.04 9.28 5.46 0.15 0.09 58.76 0.44 0.77 0.64 0.29 0.04 0.04 0.12 65.84 8.01 1.50 18.51 0.00 0.23 0.06 7.25 36.14 0.46 3.64 0.01 0.10 4.42 27.34 3.68 9.66 1.15 0.01 0.04 0.28 18.94 3.34 0.05 2005.21 85.25 50.93 0.01 0.14 0.02 0.00 30.24 2.93 3.47 0.05 1.38 0.11 0.01 95.01 6.97 17.70 0.02 0.66 0.01 0.00 103.44 1.23 20.67 0.00 0.00 0.00 0.00 4.48 0.20 1.83 1.55 2.47 0.72 0.31 27.03 1.07 1.03
serious 0.29 0.00 1.77 0.04 0.01 0.02 0.04 0.00 33.75 0.35 1.48 9.85 0.54 0.48
extremely serious 0.15 0.00 0.16 0.01 0.00 0.04 0.06 0.00 1.78 0.03 0.78 0.67 0.10 0.04
1988 (%) 11.31 0.16 32.57 18.09 2.66 1.71 0.59 2.66 26.70 0.43 1.48 1.55 0.08 100.00
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 km2, shrubland with 127.9 km2 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 km2 (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 - 61 http://www.j-es.org
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 shrubland grass land construction land water area unused land 2006(%)
cultivated land 333.67 5.17 44.36 83.83 6.10 33.29 2.53 50.17 9.10
garden plots 20.00 1.17 17.30 25.09 0.75 5.77 0.31 3.43 1.20
forest land 44.02 1.72 2449.81 1059.34 137.61 5.82 2.31 40.49 60.8
Shrub land 182.06 2.75 331.04 577.70 63.29 28.03 6.30 128.02 21.46
grass land 6.63 0.05 36.65 49.65 58.81 0.12 0.06 4.43 2.54
construction land 91.6 0.77 6.94 12.52 0.44 54.28 6.46 27.30 3.26
water area 7.65 0.08 5.98 6.04 0.77 7.09 30.83 6.80 1.06
unused land 7.37 0.06 2.67 9.28 0.64 1.50 0.46 9.66 0.51
1988 (%) 11.27 0.19 47.09 29.66 4.37 2.21 0.80 4.40 100.00
TAB 5 THE TRANSITION MATRIX OF LAND USE/ COVER IN KARST DISTRICT OF LIANGJIANG RIVER BASIN FROM 1988 TO 2006 (KM2, %) cultivated land cultivated land 198.74 garden plots 1.19 forest land 7.43 construction 9.34 water area 0.80 potential 160.59 light 2.14 middle 22.02 serious 2.10 extremely serious 0.18 2006(%) 10.25 Type
3)
garden plots 2.2 0.10 0.22 0.08 0.01 3.85 0.01 0.05 0.01 0 0.17
forest land 3.18 0.43 130.85 0.12 0.06 326.65 3.80 3.81 17.98 0.85 12.36
construction water potential land area 14.95 1.23 212.55 0.11 0.01 2.66 0.48 0.12 246.37 11.23 0.98 18.42 0.77 5.17 3.60 18.67 3.26 2007.04 0.14 0.02 30.27 1.37 0.10 95.09 0.65 0.08 103.53 0 0 4.48 1.23 0.28 69.04
light
middle
serious
7.05 0.08 4.04 0 0.01 85.33 2.94 6.97 1.23 0.20 2.73
5.09 0.01 3.88 0.23 0.10 50.97 3.47 17.72 20.69 1.83 2.64
0.29 0 1.72 0.02 0.04 33.79 0.35 1.48 9.86 0.54 1.22
extremely 1988 serious (%) 0.15 11.29 0 0.12 0.15 10.02 0.04 1.03 0.06 0.27 1.78 68.22 0.03 1.09 0.78 3.79 0.67 3.97 0.10 0.21 0.10 100.00
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 km2,and 15.17%, unused land - 62 http://www.j-es.org
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 1988 Type
2006
rocky desertification
CA
PLAN D
NP
PD
ED
AWMP DF
LSI
CA
PLAN D
NP
PD
ED
AWMP DF
LSI
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
12102
3.0564
9.3466
1.0926
141.3098 11560.3200 2.9173
21153
5.3381
19.9330
1.1371
185.0349
ESR D
4321.5300
1.0914
no- desertification karst district
POR 270022.5900 68.1948 14578 D
no-karst district
3.6817 137.0875 1.4176
273.2872 272126.7000 68.6725 11405
2.8781 119.1406 1.3890
239.0359
7.1136
43.6033
1.2198
211.7188 40598.0100 10.2451 16793
4.2378
37.2776
1.2046
189.8609
0.6458
1.1476
1.0554
53.8403
1432
0.3614
1.1928
1.0908
46.8596
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
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
4275
0.6947
1.7121
1.0943
71.0887
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
CL GP FL
44797.0500 11.3136 28167 463.2300
0.1170
0.2239
2557
656.2800
8132.4900
0.1656
1.3202
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 - 63 http://www.j-es.org
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窶認ragstats3.3, 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 1988 2006 1988K 2006K 1988FK 2006FK
TA 1011248.2800 1012069.2600 395957.9700 396267.4800 615389.6700 616009.6800
NP 298108 204838 167120 115345 249811 202129
PD 29.4792 20.2395 42.2065 29.1079 40.5940 32.8126
ED 144.8837 117.9559 155.5377 132.8818 149.3103 119.4218
LSI 366.5025 298.9512 260.8208 225.3090 307.7172 249.2083
LPI 8.6029 11.7357 21.9713 17.0214 11.7151 18.0087
MPS AWMPDF CONTAG SHDI SIDI PRD 3.3922 1.3280 50.9155 1.7333 0.7749 0.0013 4.9408 1.3165 56.2588 1.5796 0.7240 0.0013 2.3693 1.3416 59.3168 1.1233 0.5089 0.0010 3.4355 1.3242 61.5216 1.0969 0.5008 0.0010 2.4634 1.3118 49.1881 1.3784 0.6756 0.0008 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, - 64 http://www.j-es.org
their area had been reduced by 39.51 km2, 104.99 km2 and 4.31 km2 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
- 66 http://www.j-es.org