Водный режим защитных лесных полос в сухой степи Алтайского края

The south of Western Siberia is a large grain-growing region, where safe farming is impossible without protecting fields with forest belts. But as the aridity of the territory increases, their durability decreases, which hinders the afforestation of arable lands. The aim of this study has been to establish the patterns of the stands of forest shelterbelts and to substantiate their models that are most stable in dry-steppe areas. A system of middle-aged forest shelterbelts of Pinus sylvestris, Ulmus laevis and Betula pendula 7–10 m high and Ribes aureum 1.5–2.0 m high on automorphic chestnut soil has been studied. It has been established that snow deposition in the forest shelterbelts is determined by many factors: the amount of solid precipitation, wind and air temperature conditions, as well as wind permeability of the stand. By layering, they neutralize or enhance the overall effect on the snowstorm flow. The average snow depth and snow reserve in the stand nutrition zone mainly depend on the amount of solid precipitation, and in shrubless belts they also increase with density, stand height and row-spacing. In forest shelterbelts with edge rows of shrubs, the snow reserve decreases with an increase in the number and height of rows of trees, the width of the rowspacings and the distance between the row of shrubs and the row of trees. Shrubby curtains and dense 1-row forest belts, as well as 2–3-row stands in the presence of a row of shrubs on the windward side, accumulate snow more efficiently and work “for themselves”. According to the effectiveness of solid precipitation retention, they are followed by 2–3-row shrubless forest shelterbelts with row-spacing of 2.0–3.5 m and a stand density of 0.6–2.0 thousand trees/ha. Among the 2-row forest belts, more wide-row and dense plantations accumulate snow better. Increasing the number (above 3) and density of tree rows reduces their filling with solid precipitation. In forest shelterbetls, moderately dense (up to 1,000–1,100 trees/ha) biogroups of trees accumulate snow more effectively. Shrubby intermittent curtains form snow mounds and can be used as a good means of accumulating snow on inter-belt fields. More stable spring and summer soil moisture reserves are formed over the years in shrubless 2–3-row shelterbelts with moderately wide row-spacings, while moderately dense stands of pine and birch use moisture more economically.