Vegetation significantly influences evaporation, primarily by increasing evapotranspiration. This process combines both evaporation from the soil and water loss through plant transpiration.
Vegetation's Role in Evapotranspiration
According to Piao et al. (2008) and Xiangyi Li et al. (2018), vegetation promotes two key processes that contribute to increased evapotranspiration:
- Canopy Transpiration: Plants release water vapor through tiny pores on their leaves (stomata). This process is called transpiration. The more vegetation there is, generally measured by the Leaf Area Index (LAI), the greater the overall transpiration rates will be.
- Interception Evaporation: When it rains, plant leaves intercept some of the precipitation. This water then evaporates directly from the leaf surfaces. Increased LAI leads to more interception, thus contributing to greater overall evaporation.
How Increased LAI Leads to Greater Evapotranspiration
| Feature | Impact on Evapotranspiration |
|---|---|
| Increased LAI | Leads to more transpiration due to more leaf surface area |
| Greater Leaf Cover | Causes more rain interception and thus more evaporation |
| Overall Effect | Increased total evapotranspiration |
Impact on the Water Cycle
The increase in evapotranspiration due to vegetation plays a critical role in the water cycle.
- Vegetation is vital to the global hydrological cycle as it facilitates the movement of water from the soil into the atmosphere.
- This increased water vapor in the atmosphere leads to cloud formation and ultimately precipitation, completing the cycle.
Note on Research
Although there is a clear understanding that vegetation affects evaporation, research is still in progress regarding vegetation anomalies and how changes in vegetation patterns influence overall land evapotranspiration. Further studies are still needed in order to understand this part of the equation, especially in times of climate change.
