2022- 10-06 09: 1 1:4 1
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I. Background introduction
Grassland, as one of the most widely distributed and important land vegetation types in the world, has a wide distribution area. China's grassland area is 355 million hectares, accounting for 6%~8% of the total grassland area in the world, ranking second in the world. In addition, grassland has important ecological functions in maintaining biodiversity, soil and water conservation, purifying air, carbon sequestration, regulating soil erosion and sandstorms. Since the CPC Central Committee and the State Council implemented the policy of "returning grazing to grassland" in 2003, remarkable achievements have been made in protecting and improving grassland ecological environment and improving people's livelihood. "Returning grazing to grassland" is not a ban on grazing. In addition to the prohibition of grazing in some areas, many grasslands practice rotational grazing in different regions and grazing in the growing period. Reasonable grazing policy is the key to promote regional economy, prevent grassland desertification and protect people's livelihood. The study of grazing optimization also provides a scientific basis for the state and government to formulate grazing policies and grassland management decisions.
Grassland in China is mainly divided into temperate grassland, alpine grassland and desert grassland. Xilingol grassland in Inner Mongolia is a typical temperate grassland and one of the four major grasslands in China. Located in Xilin River, Inner Mongolia Plateau, the geographical coordinates are110 50 ′ ~19 58 ′, and 4130 ′ ~ 46 45 ′ north latitude. Xilingol grassland in Inner Mongolia is not only an important national animal husbandry production base, but also an important green ecological barrier, which plays an important role in reducing sandstorms and disastrous weather. It is also one of the typical fields to study the response mechanism of ecosystem to human disturbance and global climate change, and it is an important part of terrestrial ecosystem transect (NECT) of the International Geosphere-Biosphere Project (IGBP).
Grassland grazing usually considers grazing mode and grazing intensity (livestock density per unit area). Grazing methods can be divided into many kinds. Some literatures divide grazing methods into the following five kinds: continuous grazing all year round, grazing prohibition, rotational grazing in selected areas, light grazing and grazing suspension in growing season. Grazing intensity can be divided into four types: control, light grazing intensity, moderate grazing intensity and heavy grazing intensity. AccordiNG to the data in annexes 14 and 15, the grazing intensity of rotational grazing is divided into control (ng, 0 sheep/day/hectare), light grazing intensity (LGI, 2 sheep/day/hectare), medium grazing intensity (MGI, 4 sheep/day/hectare) and heavy grazing intensity (HGI)
The growth of plants meets their own needs.
Desertification is more serious. Soil hardening can be improved by taking measures, but desertification is large-scale and difficult to deal with.
The main reason of soil desertification is artificial farming, which makes the soil suffer from wind erosion, rain erosion and sun exposure. Soil erosion, frequent farming and excessive use of chemical fertilizers gradually reduce, desertification and harden the organic matter in the soil.
Soil desertification index is negatively correlated with soil hardening index.