Land is the main space for human life and production activities, and it is the most precious resource for human beings. However, with the increase of population and human demand, the shortage of land resources is becoming more and more serious. Facing this situation, it is an urgent and important task to seriously study the present situation, potential and existing problems of land resources development and utilization and formulate a series of practical countermeasures.
First, the characteristics of land resources in China
65,438+0. The land area of China is14.4 billion mu, which is large in absolute terms and small in per capita possession. Among them, cultivated land is about 2 billion mu, accounting for 13.9% of the total area of China, woodland 187 million mu, accounting for 12.98%, grassland is 4.3 billion mu, accounting for 29.9%, and urban industrial and mining traffic land120,000 mu, accounting for 8.3%.
China ranks fourth in cultivated land area, eighth in woodland and second in grassland, but its per capita possession is very low. The per capita arable land in the world is 0.37 hectares, that in China is only 0. 1 hectare, that in grassland is 0.76 hectares in the world and 0.35 hectares in China. Developed countries 1.8 hectares of cultivated land carry 1.8 people, developing countries carry 4 people and China carries 8 people. The pressure is obvious. Although China has solved the problem of food and clothing for15 of the world's population, we should also see that the non-agricultural land in China is increasing year by year, the per capita arable land will decrease year by year, and the population will put more and more pressure on the land.
2. There are various types and significant regional differences. China spans equatorial belt, tropical zone, subtropical zone, warm temperate zone, temperate zone and cold temperate zone, among which subtropical zone, warm temperate zone and temperate zone account for about 7 1.7% of the land area, and the temperature conditions are superior. From east to west, it can be divided into humid area (accounting for 32.2% of the land area), semi-humid area (accounting for 17.8%), semi-arid area (accounting for 19.2%) and arid area (accounting for 30.8%). Moreover, due to the complex topographic conditions, mountains, plateaus, hills, basins, plains and other landforms crisscross, complex and diverse types of land resources with obvious regional differences have been formed, which provides favorable conditions for the comprehensive development of agriculture, forestry, animal husbandry and by-product fishery production.
3. The proportion of low-quality land that is difficult to develop and utilize is large, and a considerable part of land in China is difficult to develop and utilize. In the total land area of the country, desert accounts for 7.4%, Gobi accounts for 5.9%, stony bare rock accounts for 4.8%, glacier and permanent snow accounts for 0.5%, plus 8.3% occupied by residential areas and roads, the land that cannot be used for agriculture, forestry and animal husbandry accounts for 26.9% of the national land area.
In addition, some land is of poor quality. Among the existing cultivated land, waterlogged depressions account for 4.0%, saline-alkali land accounts for 6.7%, soil erosion land accounts for 6.7%, red soil depressions account for 12%, secondary fertile paddy soil accounts for 6.7%, and various depressions account for 540 million mu. In terms of grassland resources, there are 900 million mu of desert and semi-desert grasslands with annual precipitation below 250mm, and about 2 billion mu of alpine grasslands distributed in the Qinghai-Tibet Plateau. The grass quality is poor and the grass yield is low. Raising 1 sheep requires about 60-70 mu, or even 100 mu of grassland, which has low utilization value. The national forest stock per hectare is only 79m3, which is 711.8% of the world average.
Second, the types of land resources utilization
Due to the complex natural conditions and diverse types of land resources in China, after thousands of years of development and utilization, various types of land use have gradually formed. The types of land resources utilization are generally divided into cultivated land, woodland, grazing land, water area, urban residential land, traffic land and other land (channels, mines, salt fields, etc.). ), glaciers and permanent snow, rocky mountains, alpine deserts, Gobi deserts, etc. According to the comparable data 1983 in World Resources, compared with other countries with large land area in the world, the proportion of agricultural land in China is relatively small (table 1).
Table 1 Percentage of agricultural land in each country (%)
Judging from the combination of land use types, there are significant differences between southeast and northwest China. Generally, the border starts from Daxing 'anling in the north, passes through Hetao Plain, central Ordos Plateau and Tongxin area of Yanchi in Ningxia to the west, and then extends to Jingtai, Yongdeng and Huangshuigu, turning to the southeast edge of Qinghai-Tibet Plateau. Southeast China is a concentrated distribution area of cultivated land, woodland, freshwater lake and outflow system, accounting for about 90% of the cultivated land in China, with a high land reclamation index, while northwest China is dominated by animal husbandry land, and 80% of grassland is distributed in semi-arid and arid areas in northwest China, with a low reclamation index.
The imbalance of water and soil resources combination is also obvious. The water in the Yangtze River, Pearl River, Southwest Watershed and Zhejiang, Fujian and Taiwan regions accounts for 8 1% of the total water in China, while the cultivated land in these areas only accounts for 35.9% of the total cultivated land in China. The water in the northern basins such as the Yellow River and Huaihe River accounts for 14.4% of the national water, and the cultivated land in these semi-humid and semi-arid areas accounts for 58.3% of the national cultivated land (Table 2). In the arid and semi-arid areas in the west, the total water resources only account for 4.6% of the whole country.
Table 2 Statistics of Soil and Water Resources in China
Cultivated land is mainly concentrated in the eastern region 14 provinces and cities where the three plains of Northeast China, North China and the middle and lower reaches of the Yangtze River are located, accounting for 59% of the total cultivated land area in China. Paddy fields are mainly distributed in the south of the Huaihe River in Qinling Mountains, accounting for about 93% of the total paddy fields in China, and dry lands are distributed all over the country, but mainly concentrated in the north of the Huaihe River in Qinling Mountains, accounting for 85% of the total dry land area in China, among which the Northeast Plain and the Huanghuaihai Plain are the most concentrated, accounting for about 60% of the total dry land area in China.
The national forestland area is115.28 million hectares. The forest coverage rate 12.98% and the forest volume157.2 million cubic meters. Forests are concentrated in the northeast and southwest regions, accounting for 50% of the national area and 75% of the stock. However, in the densely populated and economically developed areas of North China, the Central Plains and the lower reaches of the Yangtze River, there are few forest resources, accounting for only 4% of the national forest area.
Grassland is mainly distributed in the northern and western regions with precipitation less than 400 mm, covering an area of about 4.3 billion mu. Among them, the available land is about 3.3 billion mu. Grassland in the north is zonal, with grassland area accounting for about 30%, desert area accounting for about 64%, and the rest is mountainous grassland. There are about 654.38 billion mu of grassy slopes in the south of China.
Three. Land quality and potential
China's land production potential varies greatly from region to region. The humid and semi-humid areas in the east account for about half of the country's total area, but the biological output accounts for 90% of the country, accounting for more than 90% of the cultivated land, forest land and meat output in China, and more than 95% of the population. 1km2 has carried 225 people. The estimation of climatic production potential based on light, heat and water resources shows that the average output in eastern China is only 20-40% of the climatic potential, and there is still great development potential. In the arid and semi-arid areas in the west, there is drought and water shortage. The total water resources only account for 4.6% of the whole country, and the annual biological output is less than 10% of the whole country. The productivity is low, and the land carrying capacity is only 4.3% of the whole country.
According to calculation, the actual productivity (biological yield) of 2 billion mu accounts for about 3/4 of all agricultural land; The total land for forestry and grass is about 6 billion mu, but the actual productivity only accounts for 1/4 of agricultural land, and the output value only accounts for110. Not only is grain, cotton and oil completely provided by cultivated land, but 96.2% of meat production in China is also converted from feed produced by cultivated land, and most of the materials in rural areas also depend on agricultural forest network and greening of agricultural areas. It is estimated that by the end of this century, the biological yield of cultivated land will reach 23× 108 tons, accounting for 68% of the total output of agriculture, forestry and animal husbandry land, while forests and grasslands only account for 32%. By 2025, the biomass of cultivated land will still account for 70%. Therefore, it is not difficult to see that 2 billion mu of cultivated land is the essence of China's land resources, and protecting cultivated land resources is an extremely important national policy.
1. According to the survey results of China 1: 1 10,000 land resources map, among the existing cultivated land, the first-class cultivated land with good quality accounts for about 41.6% of the total cultivated land area in China; The second-class cultivated land with limited agricultural utilization and medium quality accounts for about 34.5%; About 20.3% of the third-grade cultivated land has great restrictions on agricultural utilization and poor quality, of which 3.3% is not suitable for agriculture and needs to be returned to farmland. According to statistics, if the sowing area (statistics) is taken as the step, the low-yield fields below 150kg account for 2 1.0%, the high-yield fields above 300kg account for 22.5%, and the middle-yield fields account for 56.5%. From this, we can draw the following conclusions:
L) The farmland with medium yield is the largest, with yield (56.5%) and county (56%) each accounting for more than half.
2) Medium cultivated land generally includes two types of land, one is cultivated land with good land quality and unlimited factors. Due to less investment and extensive management, the output did not reach its due level. This kind of cultivated land is about 20 million mu. As long as we increase investment and strengthen management, the output will increase rapidly. Second, the second type of cultivated land with light restrictive factors is dominated by mild flooding, mild salinity, mild soil erosion and gentle slope. Among them, drainage restriction accounts for 24%, erosion and slope restriction accounts for 17.5%, and saline-alkali restriction accounts for 13.5%. This kind of cultivated land can adjust the crop production layout according to its suitability, or take simple improvement measures to eliminate its limiting factors.
The yield-increasing benefit of middle-yield fields is higher than that of high-yield fields and low-yield fields. The yield of high-yield fields will be more, and the income will not be too high because of diminishing returns. According to the statistical data of 1985, in high-yield fields, the yield per mu is 63.64%, 350-450 kg is 34.48%, and more than 450 kg is 1.87%. The higher the output, the less the proportion, and the more difficult it is to increase production. Low-yield fields are mostly steep slopes, drought, barren land, sandy land, heavy saline-alkali land and heavy waterlogging land, which are cultivated land with serious limiting factors. Transforming low-yield fields requires a lot of investment.
Therefore, at present, we should give priority to middle-class fields and transform second-class fields to achieve the goal of increasing production in a large area in a balanced way. At the same time, it is necessary to consolidate and improve high-yield fields and transform low-yield fields in a planned way.
2. The national agricultural reserve land resources are about 500 million mu. According to its quality evaluation, the first-class wasteland only accounts for 3. 1%, the second-class wasteland accounts for 49%, and the third-class wasteland accounts for 47.9%, including saline-alkali land, marshland, red and yellow soil hills, alpine land, dry land and coastal beaches. Moreover, most of them are located in remote areas with inconvenient transportation, and the investment required for reclamation is large, so they can only be used after vigorous transformation.
The wasteland suitable for farming is mainly distributed in the north of 35 N, including Sanjiang Plain, Songnen Plain, intermountain valleys and piedmont hills in northeastern mountainous areas, eastern Inner Mongolia, Hexi Corridor, Junggar Basin, Tarim Basin and Yili River Basin. The wasteland area in these areas accounts for about 80% of the national wasteland area.
The wasteland suitable for agriculture can be reclaimed and cultivated, and it is also suitable for developing animal husbandry and forestry. We must make rational use of it according to local conditions and avoid the contradiction between agriculture, forestry and animal husbandry. About 40% of the wasteland suitable for farming is natural grassland, which is mainly suitable for reclaiming and planting pasture and turning natural grassland into artificial grassland. In addition, about 16-20% of wasteland suitable for agriculture is distributed in hilly areas of southern provinces, which is mainly suitable for developing woody oil crops and tea, citrus and other crops.
3. Pastoral areas in western China account for about half of the total land area, but the productivity of grassland pastoral areas is low, with an average of only 0. 15 kg of meat per mu of grassland. If forage grass, crop stalks and other agricultural and sideline products are used as feed quantity, the feed quantity in the west only accounts for 1 1% of the whole country, and the meat production accounts for 4.9%. Grassland productivity in western pastoral areas is not only low, but also overloaded and overgrazing, which leads to grassland degradation and land desertification. Therefore, at present, it is not appropriate to greatly increase the livestock carrying capacity in grassland pastoral areas, but to recuperate and strictly control the number of livestock.
The development potential of forage grass resources: firstly, strengthen grassland management, restore 400 million mu of degraded grassland to its original production level, and it is estimated that 30 kilograms of dry forage grass can be added per mu; Second, improve grassland, build artificial and semi-artificial grassland, establish a scientific grazing management system, and set a reasonable livestock carrying capacity by opening up water sources and eliminating poisonous weeds; The third is to develop water-deficient grasslands. According to the survey, there are about 300-450 million mu of water-deficient grassland in pastoral areas in China, and the average utilization rate is only 30-40%. After the development of water sources, the utilization rate can be expanded; Fourth, rational development and utilization of grass hills and slopes in the south, with long growth period and high yield. At present, the utilization rate is less than 20%, which has great potential.
4. The forest land in China is 3.7 billion mu, of which the forest area is 65.438+87 billion mu. Young and middle-aged forests account for about 654.38 billion mu.
According to the data of the Ministry of Forestry, there are currently 2 1 forestry bureaus whose recoverable forest resources have been basically exhausted. If the current production level continues, by the end of this century, nearly 70% of the recoverable forests of the Forestry Bureau will be completely cut, and the situation in the southern collective forest area is very serious. Therefore, it is necessary to make strategic adjustments to forestry construction and forest land layout from the perspective of protecting the ecological environment and supplying wood. That is to say, while continuing to do a good job in plain, urban greening and the three-north shelterbelt system, the strategic focus of forestry construction should be transferred to mountainous areas as soon as possible. This is not only because of the large mountainous area in China, but also because of the rational utilization of natural resources. Moreover, because mountainous areas mostly belong to the barriers of the upper reaches of rivers or plain agricultural areas, it is very important to improve the ecological environment as a whole, conserve water and cover farmland and grassland. According to the analysis of the characteristics of land resources in China, it takes a long time for the two old forest areas in northeast and southwest to recover resources, so we should pay close attention to the preparations for xinlin. Attention should be paid to the development of subtropical hills in the south, which account for 80% of the country's land area, and nearly two-thirds are low hills below 1000. The hills are rich in light and hot water, fertile soil, high land productivity, fast growth of trees, many suitable species, easy afforestation and closing hillsides to facilitate afforestation, and superior conditions for forestry development. Therefore, we should concentrate on speeding up construction, strive to become the largest timber forest and economic forest base in China by the end of this century, and avoid the problem that forest resources may not be connected with each other.
Strengthen the tending of young and middle-aged forests, transform low-yield forests, transform and update sparse forests and shrubs (about 700 million mu nationwide), update land in time, maintain water and soil, and make sustainable use.
China's reserve forest land is about 654.38 billion mu, which is mainly distributed in the hilly and mountainous areas in the northeast and south. After afforestation, it is estimated that the forest coverage rate will reach 17% by the end of this century.
5. Most freshwater aquaculture waters in China are located in warm temperate zone, subtropical zone and tropical zone, with high natural productivity. China's freshwater aquaculture area is 57.5 million mu, and the yield per mu in high-yield ponds can reach 1 000 kg, but the average yield per mu in China is less than 1 000 kg, so the prospect of increasing production is very broad.
The arable land area of seawater around shallow sea beaches and islands is 20 million mu, and the current utilization rate is insufficient 1/3. The combination of aquaculture and fishery can further improve the production potential of seawater area.