Conclusions
The assessment of the aspects presented and discussed enabled the following prem- ises:
Drought is a constant phenomenon in agriculture in Brazil, thus requiring con- tinuous prediction and monitoring to provide valuable mitigating measures.
As a result of the territorial extension, the mitigating measures are not necessar- ily identical and must take into consideration the cultural aspects of the population the climate regime, and the agricultural exploitation.
The various indices presented have proven to be adequate for monitoring and mitigating the effects of drought, nevertheless, adjustments are necessary for the use of these indices for each region and crop. For the PDSI, the parameters of the equations should be estimated for each region in Brazil.
Every state should create a Drought Monitoring and Mitigation Center, subor- dinated to the State's Agricultural Secretariat.Itshould be the responsibility of the INMET, in association with state agencies, to propose norms and to define stan- dards and policy for the monitoring and mitigation of drought on a regional and nationwide scale.
Itshould be understood that the drought phenomenon cannot be assessed and interpreted by only one field of expertise, but rather by a set of specialists and in- stitutions. Furthermore, it is extremely important that researchers and specialist in the areas of agronomy, agrometeorology, meteorology, civil defense, agro exten- sion service, and others, should be involved in the study of the drought phenom- enon.
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CHAPTER 18
Coping Strategies with Desertification in China
Wang Shili, Ma Yuping, HouQiong, Wang Yinshun
18.1
Introduction
Desertification was defined as "land degradation in arid, semi-arid or sub-humid dry areas resulting from various factors including climatic variations and human activities" in the United Nations Convention to Combat Desertification (UNCCD).
About two-thirds of the countries of the world, one-fifth of the global population and one-fourth of the land of the earth are now affected by desertification with a direct economic loss about US$ 42.3 billion every year. Desertification has become a source of poverty and a constraint to socioeconomic sustainable development.
Combating desertification, ecological improvement and sustainable development is an imperative hard task for the world.
China is one of the countries with a large area, wide coverage and heavy losses from desertification and sand encroachment in the world. With rapid increase of population and driven by economic benefits in socioeconomic development, vari- ous human activities that deteriorate vegetation in sandy areas had prevailed, such as over-grazing, wasteland cultivation, excessive firewood gathering, excessive gath- ering of arenicolous plants and irrational use of water resources. The serious land desertification and sand encroachment have been threatening China's ecological se- curity and sustainable socio-economic development.
Upon the entry of the twenty-first century, Chinese government raised its at- tention to desertification combating and incorporated desertification manage- ment oriented ecological improvement into the economic and social development plan. Consequently several significant actions were taken, including promulgation and execution of the Desertification Combating Law; release of the State Council Decision About Further Accelerating the Desertification and Sadification Combat- ing Work,formulation of the National Desertification and Sadification Combating Plan.A number of key programs on sand enchroachment prevention and control have been launched and implemented, such as the six major forestry programs, grassland protection and improvement program, small watershed integrated pro- gram.
In order to master the status and dynamic changes of desertification and sand encroachment land nationwide, national monitoring survey for desertification was carried out three times in 1994, 1999, and 2004, respectively. The results of the 3rd national monitoring survey for desertification and sand encroachment show that the expansion tendency of desertification and sand encroachment in China has
been primarily brought under control and the 'stalemate of rehabilitation and de- struction' has been realized (State Forestry Administration, 2005).
18.2
Status of Desertification in China 18.2.1
Status of Desertified Land
The land suffering desertification nationwide in 2004 was 2.6362 million km ', tak- ing up 27.46% of the territory, located in 498 counties of 18 provinces including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Liaoning, Jilin, Shandong, Henan, Hainan, Sichuan, Yunnan, Tibet, Shaanxi, Gansu, Qinghai, Ningxia and Xinji- ang.
18.2.7.1
Distribution ofdesertification indifferent Climatic zones
The area of desertified land in arid, semi-arid and sub-humid arid region is 1.15 million km2,971,800 km2and 514,400 krrr', taking up 43.62%,36.86% and 19.52%
of total desertified land area respectively.
18.2.1.2
Desertification types
Wind-eroded desertification, water-eroded desertification, salinization and freeze- thawing desertification lands cover 1.8394 million km", 259,300 krn", 173,800 km2 and 363,700 km2respectively.
18.2.1.3
Degree ofdesertification
Lightly, moderately, severely and extremely severely desertified land respectively covers 631,100 km", 985,300 krrr', 433,400 km2and 586, 400 km'.
18.2.7.4
Distribution ofdesertification invarious provinces (Autonomous Regions)
Desertification in the country is mainly located in Xinjiang, Inner Mongolia, Tibet, Gansu, Qinghai, Shaanxi, Ningxia and Hebei provinces (autonomous regions). The area of desertified land in these 8 provinces occupies 98.45% of the total deserti- fied land area.
Chapter18: Coping Strategies withDesertification inChina 319 18.2.2
Status of land most vulnerable to sand encroachment
Land most vulnerable to sand encroachment is a kind of degraded land between sand encroachment and non-sand encroachment due to over utilization of land or shortage of water resource. The area ofland most vulnerable to sand encroach- ment is 318 600 knr', accounting for 3.32% of the total country's territory, which is mainly distributed in 4 provinces (autonomous region) including Inner Mongolia, Xinjiang, Qinghai and Gansu.
18.2.3
Dynamic Changes of Desertification
Compared with 1999, the national desertified land area decreased by 37,924 km", representing an annual drop of 7585 krrr'. In terms of different desertification types, the area of desertified land caused by wind erosion decreased by 33,673 km2,
by water erosion decreased by 5525 km", while that of desertified land caused by salinization increased by 930 krrr'. In terms of desertification degree, the area of lightly desertified land increased by 90,700 krrr', moderately desertified land in- creased by 117,300 km2, while that of severely desertified and and extremely se- verely desertified lands decreased by 131,700km2and 114,200 km2respectively. As for major provinces, the area of desertified land in 16 provinces has decreased.
18.3
Development and Causes of Desertification in North China 18.3.1
Development and Cause Analysis 18.3.1.1
Historical situation
Before the term desertification was defined, Chinese scientists were more concen- trated on sandy desertification caused by wind erosion. Researches showed that in the Pleistocene about 10 thousand years ago, several kinds of severe and frequent climatic oscillations happened in China, the occurrence and reversion of desert were mainly controlled by global climate change driven by earth orbital parame- ters. Since the Holocene, especially recent 2000 years, due to the increase of popu- lation, innovation of productive tools, and increase of the extension and intensity in farming, human activities gradually became another important factor. How- ever, sandy desertification was still primarily caused by climate change. In the last one hundred years, the process of sandy desertification was affected by not only climate change, but also the intensified human activities (Dong et al. 1998). For ex- emple in Gonghe Basin of Qinghai province in China, during the 50s to 80s of 20th century, the accumulated afforestation and conservation area was 1,700 ha, but the
destructed forest area was five times this area, and the expansion area of desertifi- cation even up to 32 times this area (Dong et al. 1998).
78.3.7.2
Type ofhuman activities
In North China, where wind erosion is the main factor affecting desertification, various human activities operated, including overgrazing (30.1%), excess rec- lamation (26.9%), excess firewood gathering (32.7%), irrational use of water re- source (9.6%) and lack of environmental protection in building factories, mines and transportations (0.7%). In the southeast of Horqin grassland, which once was sparse forest grassland, 1,333 square kilometer ground were cultivated once, some of them even two or three times during the last one hundred years. The percentage of shifting sand area occupying total land increased from 14% in late 1950s to 32%
in 1970s. In late 1980s and 1990s, it was up to 41.2% and 54% (Zhu 1998).
78.3.7.3
Key vulnerable region
The most severe area of desertification in Northern China is farm-pastoral transi- tion zone and rainfed agriculture area with annual precipitation of 200 mm- 400 mm and annual evaporation of about 2000 to 2500 mm. Since the region is at the edge of East Asia monsoon, there is vulnerable environment and sensitivity to cli- mate change, resulting from low rainfall, arid climate, loose soil, and frequent high wind. During early 1950s to late 1970s, as a result of excess reclamation and fire- wood gathering, desertification developed further including acceleration of wind erosion of sandy grasslands and increase in the area of shifting sands. Until late 20th century, it began to reverse in most area according to the monitoring results from remote sensing. An example is Xijingzi village in semi-arid area which be- longed to Shangdu County in Inner Mongolia where sandy desertification area made up about 41.3% of whole region in the early 1960s, and then jumped to 57.8%
in 1978. Owing to adjustments in land use and countermeasures, the percentage dropped to 22.7% in late 1980s.
The climate shifted to warm and dry in these areas. However, great changes in land use have been taken place since 1980s. So it could be found that environmen- tal changes resulting from climate change provided a basis for desertification in farm-pastoral zone; but improper land use leads and accelerates its formation and development.(Xue et al. 2005; Li and Lu 2002).Itis obvious that desertification in semi-arid and semi-humid areas in China during modern time is due to complicat- ed interactions among climate change, human activities and desertified land under vulnerable ecosystems. (Dong et al. 1998).
Chapter 18: Coping Strategies withDesertification in China 321 18.3.2
Possible influence of climate change ondesertification
Future climate change would continue to influence the development and adverse processes of desertification. On the basis of meteorological data at national lev- el, the influences of climate change on desertification in China were estimated by HADCM2 model (Ci et al. 2002; Ci 1994). The results illustrated that if CO2dou- bled and temperature increased by1.5DC in 2030, the desertification area would expand 184,023 km2•In 2056, another 175,024 km2would be desertificated. Ac- cording to estimates from statistical regression prediction model (Dong et al. 1997;
Shang et al. 2001), rising temperature and decreasing precipitation would lead to further desertification expansion in the future 80 years in northern desertification land. Another research also indicated that the development process of desertifica- tion in North China would be rapid and severe during the first ten years in 21stcen- tury with climate change (Shang et al. 2001).
Moreover, recent studies made clear that during the future 10 to 50 years, tem- peratures might be higher by 1.9 to 2.3DC,precipitation would increase by 19%
in Northwest China (Ding 2002). It will be advantageous to control natural ex- pansion and accelerate the adverse process of desertification. However, there are uncertainties in long-term climate change, and regional climate is also likely to change to warm and dry. Thus, the postive influence of increasing temperatures and precipitation on desertification should not be overestimated.
18.4
Desertification Monitoring inChina 18.4.1
Indicator system for desertification monitoring and evaluation
In order to make clear the status and damage degree of desertification and to op- erate early warning, it is essential to establish a scientific indicator system for de- sertification monitoring and evaluation. In 1977 at the United Nation Confer- ence on Desertification (UNCOD) held in Nairobi, a "Map of the World Distribu- tion of arid Regions" at 1:25 million scale was prepared by FAO, UNESCO, WMO and UNDP together, and the global desertification was evaluated (Lu et al. 2000).
Aimed at making desertification maps and evaluating desertification status, indi- cator system was paid more attention by many scholars and international organi- zations (Berry and Ford 1977; Reining 1978; FAO and UNEP 1984; Oldeman 1998;
Marbutt 1986; Hunsaker and Carpenter 1990; Hammond 1995; Rubio and Bochet 1998; and Dregne 1999).
A series of indicators for sandy desertification evaluation was determined in China in the past (Zhu and Liu 1984). In recent ten years, more progresses were made in the studies of indicator system for desertification monitoring and evalua- tion (Wang 2003). According to the definition of desertification and its character- istics, an indicator system was developed consisting of four components: driving forces indicators, state indicators, impact indicators and control indicators (Wang
2003).Itwas pointed out that for national or regional level the first step is to de- velop a frame of indicator system at macroscopic level. On the basis of it, execut- able indicator systems could be established at different areas. Then relative data are gathered according to the indicator system to monitor and evaluate desertification (Wang 2003; Wu et al. 2005).
18.4.2
Desertification monitoring inChina
18.4.2.1
National desertification surveys in the history ofChina
From 1994 to 1996, the State Forestry Administration (former the Ministry of For- estry) of China organized experts and technicians to investigate desert, gobi and san- dy desertification land in whole country. China national maps of desertification land distribution at 1:1 million and 1:2.5 million scales were made in 1996 respectively, and China Country Paper to Combat Desertification was finished (Wang 2003).
The second nationwide desertification survey was carried out in 1999.The frame of indicator technical rules for desertification evaluation consists of 3 climate zones, six types ofland use and 4 desertification land types.
The 3rdNational Monitoring Survey for Desertification and Sand Encroachment was completed in 2004 under the auspices ofthe State Forestry Administration and with the involvement of such sectors as agriculture, water conservancy, environ- mental protection, meteorology and the Chinese Academy of Sciences. The focused ground survey is combined with interpretation of remote sensing data, as well as application of GIS and GPS. About 156 million units of information was obtained based on investigation in 5.02 million sites. A National Geography Information Management System for Desertification and Sand Encroachment was established.
18.4.2.2
Content and mission ofChina's desertification monitoring 18.4.2.2.7
Scope ofmonitoring
Itconsists of arid, semi-arid and sub-humid area, distributed generally in ten prov- inces belonging to North and West China and involving 270 counties. Key moni- toring area was in farm-pastoral transitional zone occupying 82 counties of9 prov- inces of North China.
78.4.2.2.2
Contents ofmonitoring
The status of desertification land distribution and dynamic macroscopic data in arid areas for the state, provinces and typical regions are requested to be provid- ed at definded times. And maps of desertification land distribution should be pre-