The rotten layer of forest surface litter is increasing, forming a thick humus layer, just like a huge sponge that absorbs rainwater, which has powerful functions of absorbing water, delaying runoff and weakening flood peak. The roots of forest vegetation can firmly fix the soil, prevent the land from being washed by rain, prevent soil erosion and prevent land desertification.
wind prevention and sand fixation
Desertification is a major disaster in the world today, and afforestation is one of the effective measures to prevent wind and fix sand. Due to the blocking and friction consumption of forest trunks, branches and leaves, the wind speed entering the forest area will be obviously weakened. At present, shelterbelts built in various parts of China have played a great role in preventing wind and fixing sand and improving ecological environment.
Regulating climate
Forests can regulate regional climate in a certain range, especially farmland forest network and windbreak belt can significantly improve farmland microclimate.
Forests can reduce wind speed, adjust temperature, improve air and soil humidity, reduce surface evaporation and crop transpiration, and prevent disasters such as dry hot wind, hail and frost.
The dense forest canopy can absorb, scatter and reflect part of solar radiation energy in summer, thus reducing ground warming. Although most forest leaves wither in winter, dense branches can still reduce the wind speed blowing across the ground, reduce air flow, and play a role in heat preservation and moisture preservation. According to the measurement, the temperature of forest in summer is 2~4℃ lower than that of urban open space, and the relative humidity is high 15% ~ 25%, which is lower than that of asphalt concrete cement pavement 10~20℃. Because the roots of trees go deep into the ground, they constantly absorb water from deep soil for transpiration, which increases precipitation.