Hydrological Impacts of Forest Ecosystems

Forest ecosystems exert profound control over the movement, storage and quality of water at multiple scales. Through canopy interception, precipitation is redistributed in space and time, moderating the intensity of rainfall reaching the soil. Root systems enhance infiltration, increasing soil moisture storage and sustaining baseflow during dry periods. At the same time, evapotranspiration by vegetation returns water vapour to the atmosphere, influencing local humidity and precipitation recycling. The balance of these processes determines water yield—the total discharge from a catchment—and underpins services such as flood regulation, groundwater recharge and maintenance of river flows during drought. While afforestation often reduces immediate streamflow at small catchment scales, forests may enhance regional precipitation and long-term water availability through atmospheric feedbacks. Landscape configuration, tree species, age class and climatic setting all modulate hydrological outcomes, with implications for water security, land management and climate adaptation worldwide.

Research from Nature Portfolio

Work in seasonally dry tropical woodlands has introduced an optimum tree-cover theory, demonstrating that groundwater recharge peaks at intermediate canopy densities. Below this optimum, additional trees contribute more to percolation than they withdraw by transpiration, increasing recharge; above it, higher water use outweighs infiltration benefits. Field measurements of drainage and transpiration calibrated to groundwater budgets revealed that moderate tree cover can improve aquifer replenishment, challenging the prevailing view that all afforestation invariably reduces water availability. These findings guide tree-planting and management strategies aimed at enhancing water resources in water-limited landscapes.

Hydrological Impacts of Forest Ecosystems publication trend

The graph below shows the total number of articles in hydrological impacts of forest ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Canopy interception: The process by which precipitation is captured by leaves and branches before reaching the ground.

Evapotranspiration: Combined loss of water to the atmosphere by evaporation from soil and water surfaces and by transpiration from plants.

Baseflow: The portion of streamflow sustained between rainfall events by groundwater seeping into the river channel.

Groundwater recharge: The process by which water infiltrates the soil and percolates downward to refill aquifers.

Runoff: The flow of water over land surfaces towards streams or rivers, generated when soil infiltration capacity is exceeded.

Water yield: Total annual water discharge from a catchment, comprising surface runoff and baseflow.

Catchment: A defined area of land where all precipitation collects and drains to a common outlet such as a river or lake.

References

1. Ecohydrological processes and ecosystem services in the Anthropocene: a review. Ecological Processes (2017).
2. Intermediate tree cover can maximize groundwater recharge in the seasonally dry tropics. Scientific Reports (2016).
3. Investigating human-induced threat to hydrological regime of Lake Chilwa Basin, Malawi. Applied Water Science (2023).
4. Spatial and temporal based deforestation proclivity analysis on flood events with applying watershed scale (case study: Lasolo watershed in Southeast Sulawesi, Central Sulawesi, and South Sulawesi, Indonesia). International Journal of Disaster Risk Reduction (2023).
5. The Impacts of Native Forests and Forest Plantation on Water Supply in Chile. Forests (2019).