Shelterbelts for farmland in sandy areas
Type: Technologies
Creation: 2010-12-15 13:34 Updated: 2019-03-13 15:16
Compilers: Meili WEN
Reviewers: David Streiff, Deborah Niggli, Alexandra Gavilano
Country/ region/ locations where the Technology has been applied and which are covered by this assessment
- Country: China
- Region/ State/ Province: Inner Mongolia Autonomous Region
- Map: View Map
Description of the SLM Technology
Short description of the Technology
Belts of trees, planted in a rectangular grid pattern or in strips within, and on the periphery of, farmland to act as windbreaks.
Detailed description of the Technology
Shelterbelts to protect cropland are a specific type of agroforestry system comprising certain tall growing tree species. Such shelterbelts around farmland help reduce natural hazards including sandstorms, wind erosion, shifting sand, droughts and frost. They also improve the microclimate (reduced temperature, wind speed, soil water loss and excessive wind-induced transpiration) and create more favourable conditions for crop production. Thus the establishment of shelterbelts plays a crucial role in the sandy drylands that are affected by wind and resultant desertification
especially during winter and spring. Where there is irrigation, the shelterbelts protect the infrastructure from silting-up with wind-borne sediment.
Strips of tall growing species (15-25 m) of poplar (Populus spp.) or willow (Salix spp.) were originally (from 1960s onwards) planted in a 400 by 600 m rectangular grid pattern within extensive areas of cropland, with an extra belt of windbreaks on the windward side (against the prevailing wind). Generally, the distance effectively protected is 15-25 times the tree height. Strips are of variable width, consisting of 2-5 tree lines (1-3 m apart) with trees planted every 1-2 m within the lines. Selective felling is used to maintain adequate growing space and the protective effect of the trees.
The impact of the shelterbelts depends on the planting pattern of the trees (the format of strips and grids), the orientation of the shelterbelts in relation to the wind, the spacing between, and the width of each strip and the type of trees planted. The specific design is primarily based on preventing the negative effects of wind, but depends also on local conditions such as the layout of the land, the location of the roads, farm boundaries and irrigation canals. Ideally the tree strips are perpendicular to the prevailing wind direction, and the angle between the strip and the prevailing wind is never less than 45 degrees. The structure of the strips determines the way the wind is controlled, ranging from blocking the wind
to letting it diffuse through semi-permeable shelterbelts. The best effect is achieved if the wind is not blocked entirely, as this can cause turbulence.
The ownership of the land and the shelterbelts still rests with the state, but management has been more and more transferred to individual households. On condition that the impact of the shelterbelt is not affected, the local forestry agencies now allow some felling of mature trees - on a rotational and selective basis, for timber and firewood. Pine trees (Pinus sylvestris var. mongolica and P. tabulaeformis), which command high value as timber for construction, and fruit (and cash) trees like the apricot tree (Prunus armeniace) are increasingly used.
Photos of the Technology
- 📍 Inner Mongolia
- 🗓 2002-01-06
- 📷 HAI Chunxing (Beijing China)
- 📷 Lingqin Meng
- 📷 anonymous
