How do forests play an important role in maintaining the forest supply?

Question

how does it affect the quality of water??

Answer 1

By providing the seeds, spores etc. for reproduction. Trees beget trees...

How can forests improve watershed health? Forests are the least polluting land use, a mainstay for producing clean water and viable wildlife habitat, and a major factor in urban quality of life. Expanding our forest area can reduce nutrients in our streams and the Chesapeake Bay, a fundamental step in restoration. Targeting forests to sensitive areas, such as streamsides, shorelines, seeps, steep slopes, erodible soils, or headwater areas, can prove particularly beneficial for water quality and riparian and aquatic habitat.

Other major forestry programs, stewardship, fire, urban, and health, are integrated into the watershed program. Stewardship efforts support expanding and maintaining forest in a sustainable condition. Fire efforts reduce risk of catastrophic wildfire that can harm water quality. Urban efforts expand trees in built environments where they play key roles in mitigating stormwater flows, reducing heat island effects, and reducing air pollution. Health programs minimize risk of wide-scale defoliation or tree dieback that can release surges of nutrients, degrading water quality in the short term. Forest utilization efforts include support for Best Management Practices, necessary and effective for avoiding watershed impacts from forestry operations.

Forests are an important tool in long-term, low-cost protection of water supplies. Concentrations of nitrate from forested watersheds typically average 1 mg/l or less, compared to a drinking water standard of 10 mg/l. Runoff from watersheds dominated by other land uses such as agriculture or development is often 3 to 15 times as much. Work has focused on the 1) location of forests, and 2) condition of forests. Maintaining forest cover in critical locations such as floodplains, seeps, steep slopes, headwaters, and close to streams can help avoid major deterioration in water quality and increases in treatment difficulty and cost. Forests adjacent to consistent nutrient sources (such as fertilized crops or lawns) can reduce nitrogen before it reaches the reservoir, especially on shallower soils where tree roots reach the groundwater. The condition of the forest also affects ability to protect water quality. Forest condition includes characteristics such as tree health, distribution of tree and stand sizes and ages, and number of layers of vegetation (e.g., herbaceous, shrub, subcanopy, midcanopy, upper canopy). Disturbances such as windstorms or hurricanes are infrequent but inevitable. Stands with multiple layers of vegetation and a range of ages and sizes of trees can withstand loss of trees most susceptible to damage without losing all of its functions for erosion control and infiltrating water. Forest management near reservoirs takes into account the potential for multiple canopy layers, matching species to site conditions, and opportunities to maintain actively growing forests next to nutrient sources.