##Most of the grassland in our country has degraded or is degrading. The grassland of medium degradation (including sandification and alkalization) is as much as 130 million hectares.
Grassland and Degradation of Grassland
##Grasslands in China mainly distribute in arid and semi-arid regions include 398 counties (banners, cities) in 12 provinces (areas) such as Inner Mongolia, Ningxia, Xinjiang, Tibet, Qinghai, Gansu, Shaanxi, Shangxi, Hebei, Liaoning, Jilin, and Heilongjiang. The total area is 4,903,900 km2. Among them, there is 2,742,200 km2 of grassland, which is 69.8% of overall grassland area in whole country while there is 1,377,700 km2 of degradation grassland, which is 50.24% of total amount.
##Grassland degradation shows that vegetation are degraded; output of grass reduced; poisonous, harmful and low-grade grass grow up; soil is sandificated and eroded by wind; soil and water loss; soil is salified; the weight of grazed livestock is reduced; mouse and inspect pest become rampant; productivity of grassland are destroyed a lot.
##The degradation of grassland has several reasons. It is the result of combination between natural and artificial factors. Affected by the greenhouse effect, temperature raise up, rainwater is reduced, more and more droughts appear in the whole world. Especially in spring, high temperature, drought, and strong wind have great influence to grasslands. However, the most important reason is unreasonable development and utility of grassland by human.
1.) Grazing overload. Grazing beyond the capacity of grassland is the main reason of degradation.
The pverload rate of lifestock in Chinese grasslands is about 50-300%. Due to the absence of pasture during winter and spring, the grassland has weak disaster resistance, and the pasture is over-eated from the very beginning of bing green. Therefore, it is difficult for the grass to renew its vital force.
2.) Blind land reclamation. In recent decade, only in the 4 provinces of Heilongjiang, Inner Mongolia, Gansu, Xinjiang, there are more than 29,000,000 Mu area of grassland have been reclaimed to plant cereal crops. Most of glebes have severe result of sandification and degradation, even total crop failure. There are 1,400,000 Mu area has been desolated, which is 49%of total reclaimed area.
3. )Severe deforestation and dig, which severely destroy grassland vegetation. A large number of people who engage in agriculture come to grassland to dig medicinal materials such as flagelliform nostoc, liquorice, and Chinese ephedra, fell frutex such as diversiform-leaved poplar, and sacsaoul, or dig root in order to get some fuel.
4.) Abusing water resource. To develop irrigation in grassland makes people use water immoderately, and causes flooding, at last has the result of salinization of soil.
##Main measures for grassland degradation prevention and control are as follows: Firstly, to forbid grassland reclamation, prevent further destroying grassland, stop reclamation and back to plant grass, plant grass in an enclosed area, renew grassland vegetation. Secondly, to manage grassland well, carry on contract and responsibility system well, limit the top quantity of livestock in the grassland, forbid overload grazing according to the law. Thirdly, to construct well on biology environment. The whole society should pay attention to the biology environment in grasslands since it affects not only the local pastoral production and life, but also survival environment of people lived in other area. The super flood in 1998 has great relationship with destroyed vegetation of grassland and forest in upper and middle reaches of Changjiang River. Sandstorm, which appeared so many times in north this year, also has great relationship with degradation of grassland and sandification in vast arid and semi-arid region. Therefore, the whole society should pay attention to the biology environment construction in our country.
##The essence of grassland degradation is that a big number of substance being taken away from the grassland, which could not get any compensate, and which income falling short of expenditure. This violates the basic principles.
##The degradation of grassland is a dynamic succession. It has both of evolutionary and staggered character. In accordance with its order and degree of degradation, it may be divided into three kinds as follows:
1.) Light degradation: Pasture continually being mowed, eaten or gnawed. It has no time for growing up and accumulating nutrient. Its vital force is reduced. Its height and be cover degree is decreased. The output of pasture is about 20%-30% less than the normal grassland, but the component of it does not change a lot.
2. )Middle degradation: Fine pasture among grass lay gradually reduces because of over utility. Bad dainty, short and dense, poisonous and harmful plant correspondingly increases. While the grassland vegetation become to low output and low quality, the structure, physical and chemical character of soil become worse. The output of pasture decreases about 30%-40%. Pasture providing for grazed livestock is severely absent.
3. )Severe degradation: The condition of vegetation and soil become further worse. The output of pasture reduces at least 40%. Severe erosions appear in grasslands. Livestock could not get enough nutrient, they could not grow and develop normally, their reproduce ability fails, their sizes become small, or low reproduced livestock replaces high reproduced livestock. Both sides of grassland and livestock suffer. The throughput and bio-function of the whole grassland severely decrease. If this procedure could not be turned and if it goes beyond the support limit of bio-system of the grassland, wind erosion, water erosion, sandification, salinization, and infertilitation will come up. Even the collapse of bio-system in grassland will appear, the grassland will loss its reproduction ability of substance, and the grass will not exist no longer.