保护生物多样性论文：中国老挝跨境生物多样性保护区的林地变化_英文_.pdf

J Geogr Sci 2010 20 6 889 898 DOI 10 1007 s11442 010 0818 1 2010 Science China Press Springer Verlag Received 2009 11 14 Accepted 2010 03 25 Author HEMMAVANH Chanhda 1970 male Ph D Vientiane Capital Laos specialized in forest land use planning E mail chanhda2006 Forest land use change at Trans Boundary Laos China Biodiversity Conservation Area HEMMAVANH Chanhda1 2 3 YE Yanmei1 YOSHIDA A2 1 Land Resource Department Zhejiang University Hangzhou 310029 China 2 Tea Research Institute Zhejiang University Hangzhou 310029 China 3 Lao Government Secretary Board Office Prime Minister Office Lao PDR Abstract This paper analyzed forest land use change in Trans Boundary Laos China Biodi versity Conservation Area which is called Namha National Biodiversity Conservation Areas Namha NBCAs with 1992 and 2002 TM ETM Based on GIS and statistical methods the intensity state index of land use change and transfer matrix were used to study spa tio temporal land use change in the region The results showed that the area of forest land decreased greatly also the area of bamboo and grassland decreased The other way round the area of unstocked forest slash and burn and rice paddy land increased As a whole the intensity of forest land change was higher but others were lower From the transfer matrix most of the forest land changed into unstocked forest and urban area some to slash and burn The grassland and bamboo were mainly transferred to forest and unstocked forest The un stocked forest land mostly came from forest land and grassland It was showed there were three main causes of the land use change namely opium poppy cultivation rubber plantation and also ecotourism activities and finally some policies were developed in order to address the land use change in the study areas Keywords land use change rubber plantation opium poppy cultivation Namha NBCAs Laos 1 Introduction Land use and land cover change LUCC contributes to the global changes and constitute the essential reasons for that LUCC affects climates biogeochemistry and biological diversities profoundly and these impacts would be far beyond spatial and temporal scales Li 1996 Chen 2003 and thus what is the eco environment response to LUCC and how to calculate become the core problems both in the fields of global change research and land research And the results of such studies are expected to be useful in utilizing land more efficiently LUCC is a complex process subject to the interactions between natural and social systems on different temporal and spatial scales Veldkamp and Lambin 2001 Liu and Chen 2002 Various methods have been employed to reveal regional LUCC to explore the driving fac tors and mechanism of LUCC even to simulate the process of LUCC Veldkamp and Lam 890 Journal of Geographical Sciences bin 2001 Pontius and Schneider 2001 Lambin et al 2001 Ding et al 2007 Munroe and M ller 2007 Lee et al 2008 However the on going researches on integrated eco environment response to LUCC were mostly qualitative investigations Some quantitative studies mainly focused on the impact of LUCC on single environmental factors e g atmospheric environment soil environment water environment bio diversity etc Shi et al 2008 Tian and Li 2006 Wu et al 2006 Chen et al 2006 Zhang et al 2007 An understanding of land use change has tremendous implication for land management and planning and is also the key factor for sustainable development The objective of this study was to analyze the land use change during 10 years based on Landsat TM and to find out the main causes for the land use change and finally sustainable land use management was developed for this study area 2 Study area and data used 2 1 The study area Namha National Biodiversity Conservation Areas NBCAs is located in Luang Namtha Province Latitude 20 33 21 15 N Longitude 101 07 101 37 E Figure 1 It is one of the 20 NBCAs in Laos which was established in 1993 under decree 164 PM of the Lao Gov ernment with a total area of 219 409 ha elevation 560 2094 m it is contiguous with the Xiang Yong Protected Area in Yunnan China Based on an analysis by Wild Conservation Society in Laos about 32 of the Namha NBCAs contain unbroken dense mixed deciduous forest and 47 is a mosaic of forest types of varying maturity Hedemark and Vongsak 2003 Thirty seven large mammal species including Asian Tiger Malayan Sun Bear Clouded Leopard Asian Elephants and Black Cheeked Crested Gibbons have been con firmed in the NPA in addition to over 288 species of birds Tizard 1997 At present there are 19 villages within the protected area s boundaries and an additional 85 villages just out side its borders These rely heavily on the Namha NBCAs forests for food fuel medicine and cultural purposes Nam Ha NPA and WCS 2004 The majority of people living in and around the Nam Ha NPA are Ahka Kmhmou Lanten and Hmong Because of its signific ance in terms of habitat and diversity of species the Nam Ha NPA has been designated an Figure 1 Study areas HEMMAVANH Chanhda et al Forest land use change at Trans Boundary Laos China 891 ASEAN Natural Heritage Site The cultural and natural resources of the Nam Ha NPA are also the province s main tourist attractions with over 70 of tourists stating that they are interested in guided tours into the protected area Schipani and Marris 2002 2 2 Data source Satellite data used in the study included Landsat TM acquired in August or September 1992 and Landsat TM was acquired in May or September 2002 The land use data was obtained from interpreting of the Landsat TM The land use classes and definitions were based upon Food and Agriculture Organization FAO recommendation which was worked out by Mr Josef Fidloczky 1987 A minor revision was made in 1990 at the start of the National Forest Inventory mainly in order to make it adapted to ground survey At the same time the land use classes were put together into 7 land use types namely Dense Forest Bamboo Un stocked Forest Slash and Burn Rice Paddy Grassland and Urban Land The definition was used to classify the forest land use types in the study area as 1 Area of Dense Forest is defined as areas being suitable for forest production and hav ing a tree cover with a crown density of at least 20 Forest Plantations are excepted from the rule of a minimum crown density 2 Area of Bamboo is defined if an area is covered with bamboo and the over storey has a crown cover less than 5 it should be classified as Bamboo 3 Unstocked Forest Land is previously forested areas in which the crown density has been reduced to less than 20 because of logging slash and burn or other heavy disturbance If the area is left to grow undisturbed it becomes forest again 4 Slash and Burn is an area where the forest has been cut and burnt for temporary culti vation of rice and other crops The area should be classified as Slash and Burn from the time of clear cut until one year after it has been abandoned Areas being prepared for clear cut but not yet clear cut and areas that have been abandoned for more than 1 year should not be classified 5 Rice Paddy area permanently being used for rice cultivation Old paddy that has been abandoned and not been in use for more than one year should not be classified as Rice Pad dy 6 Grassland is an unfertile or degraded land on which no trees or shrubs grow It might be an area that is too dry for tree growth that has been covered by grasses It could also be an area that has originally been covered by trees which has been heavily disturbed by cutting and fired and gradually depleted One reason for absence of trees could be that large areas having been deforested are short of seed supply from surrounding forest and areas being burnt over and over again for production of fodder for hunting purposes etc 7 Urban area includes all areas being used for permanent settlements such as villages town public gardens etc It also includes roads having a width of more than 5 m and areas under electric high power lines as well as any types of land under higher power lines except Rice Paddy 2 3 Methods Based on the land use data this article analyzed spatio temporal land use change in Namha NBCAs with dynamic index of land use and land use transfer matrix Dynamic index of 892 Journal of Geographical Sciences land use describes the speed of land use change quantificationally It is very important to compare land use change and to forecast direction of land use change There are single dy namic index of land use and integrative dynamic index of land use The single dynamic in dex of land use describes the speed of one land use change and the formulation is as the following 1 100 ha a UU K UT where K is dynamic index of one of land use during the period of time Ua is the area of land use at the beginning of the study Ub is the area of land use at the end of the study T is the period of time when the unit of T is year K is the annual rate of one land use change in the study area Integrative dynamic index of land use describes the speed of the land use system in the re gion The integrative dynamic index in some region is given as the following 1 1 1 100 2 n ij i n i i LU LC T LU 1 where LUi is the area of land type i at the beginning of the study LUi j is absolute value of the area that land type i changed into other land T is the period of monitoring time when the unit of T is year LC is the annual rate of one land use change in the study area The land use transfer matrix describes the conversion among land use types k i j A and 1k i j A are two land use maps Based on algebraic methods the following formula can be obtained 1 10 land types10 kk i ji ji j CAA bamboo grassland Single dynamic index of land use describes speed of one land use change during a period of time From Table 1 it was found that the dynamic index of dense forest was 0 32 It meant that forest changed rapidly in the study area during the period Although the area of rice paddy land changed much their dynamic indexes were very high because of the large area Dynamic index of bamboo land was 7 00 and it meant water decreased rapidly too Land use transfer matrix can be obtained by overlaying land use maps in 1992 and 2002 From Table 2 it was found that most of the dense forest land that decreased was used for unstocked forest slash and burn rice paddy and some was used for urban land Most of un stocked forest that increased was conversed from dense forest Some of the unstocked forest that increased was conversed from grassland It was the main process that dense forest land conversed to unstocked forest and slash and burn On the other hand the urban land that increased was still occupied by dense forest Land use change was obvious in Namha NBCAs during the 10 years Human use of land alters the structure and functioning of land use ecosystem and can influence how ecosystems interact with the atmosphere aquatic sys tem and surrounding land Table 2 Forest land use transfer matrix in the study area unit ha Forest Bamboo Unstocked Forest Slash and Burn Rice PaddyGrassland Urban Land Total area in 2002 Forest 14208 3595 16043 475 0 1921 0 164082 Bamboo 569 550 444 0 0 0 0 1563 Unstocked Forest 23359 1070 16138 575 0 1945 0 43088 Slash and Burn 1727 0 426 401 0 0 0 2554 Rice Paddy 688 0 201 46 27 0 0 962 Grassland 1068 0 472 0 0 5608 0 7148 Urban Land 11 0 0 0 0 0 0 11 Total Area in 1992 169471 5215 33725 1497 27 9474 0 219409 3 3 Causes of land use change in the study area According to the data analysis and also field observation there are many causes for land use change in the study area such as slash and burn opium poppy plantation agricultural de velopment road construction urban development tourism development rubber plantation and so on In case of this study area there are three main issues namely opium poppy plan tation ecotourism development and rubber plantation which may impact to land use change in the study area Opium Poppy Plantation According to the 2006 opium poppy survey Opium poppy cultivation area was found in 7 provinces of the northern part of Laos including the study areas The area of opium poppy plantation area is maximizing 26 837 ha in 1998 decreased to 2500 ha in 2006 93 lower than in 1998 26 837 ha But 2006 witnessed a 39 increase compared with 2005 1800 ha It can be assumed that the actual area harvested was smaller due to the vigorous eradi HEMMAVANH Chanhda et al Forest land use change at Trans Boundary Laos China 895 cation efforts by the government part of which took place after the aerial survey UNODC 2002 2003 2004 2005 2006 See Figure 3 Opium poppy as part of the shifting cultivation upland farming system is cultivated in some of the most remote isolated and least accessible regions of northern Laos These re gions have some of the highest levels of poverty in the country and in some areas may have sensitive conditions that could affect national security and stability These upland moun tainous areas lack the socio economic and physical infrastructure that is a prerequisite for development Many problems are associated with such areas villages often have no roads and reaching them requires days of walking there is a lack of access to health education and water many ethnic group families have a poor understanding of the Lao language while women especially have heavy workloads families can be rice deficient for up to four months of the year and livestocks also suffer from poor health and nutrition Rubber Plantation Development China is projected to consume 30 of world rubber production by 2020 with an annual need for 11 5 million tones of natural rubber by that year after passing the United States as the world s largest consumer at 3 45 million tones or 18 2 of total consumption in 2002 At present it can only produce 4 million tones annually Much of the demand is being driven by the country s booming automobile industry where the number of vehicles is estimated to increase to around 200 million by 2020 from 10 million in 2005 To meet its needs China has become the largest investor in Laos outpacing neighboring Thailand and Vietnam Most of hat investment has come in the agribusiness industry in par ticular rubber An individual with knowledge of the Lao rubber industry who requested anonymity reported that the Chinese accounted for an estimated US 20 million in invest ments in northeast Laos out of a total 26 million invested Rubber cultivation is new to northern Laos with the first plantation established in north ern Laos in Hat Nyao village in 1994 by ethnic Hmong refugees who had fled to China dur ing the Indochina War and later returned from exile with substantial rubber growing exper tise Major expansion of the crop began around 2002 with substantial foreign commercial interest making inroads into northern Laos in 2004 Today forest areas are being cleared in ever expanding areas across the country to make way for new plantations Luang Nam Tha province in the northwest has the largest amount of total hectares under rubber cultivation while plantations are sprouting up in other northern provinces such as Udomxai and Pongsali and especially in Bokeo adjoining Myanmar along the almost fi nished Route 3 that will connect southern China to northern Thailand A 2006 survey by the Forestry Research Center found nationwide a total of 11 778 ha was already under rubber tree cultivation with a total of 181 840 ha in new plantations planned One knowledgeable source estimated that at present more than 10 000 ha of rubber had been planted in Luang Nam Tha province Vieng Phoukha Department of Forestry 2006 The number of hectares in nearby Vieng Poukha including a 3000 hectare spread granted by the government to a Sino Lao consortium and Na Lae districts is also growing rapidly and some part of unstocked forest and slash and burn fields had been cleared and replaced with small to intermediate rubber plantations in close proximity to a number of trekking routes in Muang Sing and Namtha district Alton et al 2005 896 Journal of Geographical Sciences Ecotourism Development From 1998 2004 the number of annual tourist arrivals to Luang Namtha Province in creased from 18 600 to 41 658 and during that period the province consistently attracted about 5 7 of the entire Lao tourism market In 2005 Luang Namtha welcomed over 49 000 visitors LNTA 2005a Also rising is the average daily expenditure of tourists which increased from 9 per day in 2000 Schipani and Pakasy 2000 to 16 per day in 2005 LNTA 2005b There are a total of 50 accommodation establishments with 536 rooms and 18 restaurants spread over the province s five districts with most concentrated in Nam tha and Muang Sing Since the late 1990s culture and nature based tourism has established itself as one of the province s top earners of foreign exchange and is a major employer Based on 2005 arrival and expenditure data it is estimated that tourism in Luang Namtha generated over 3 15 million in foreign exchange that year Most of the wildlife namely wild plants and wild animals were collected from Namha NBCAs for household consumption and also sold to the tourists Shifting Cultivation Shifting cultivation was a legitimate and rational form of land use in the study area at a time when population was small and forest cover was much more extensive This type of agricultural system in the study area is consisted of the clearing and cultivation of a new piece of land for 2 to 3 years followed by a fallow period of 10 to 12 years Complete clear ing of all vegetation was rarely done and during the fallow period a secondary vegetation cover developed soil fertility was restored and soil loss through erosion was limited This is a very old practice that is still going on in Laos Every year the villagers need to clear forest to grow food crops for their livelihood However it is now widely accepted that shifting cultivation in many parts of the study area possesses a serious impediment to rational forest management and sustainable use of soil and water resources Ma