Terrain Influence on Hydrologic Pathways Linking Precipitation to Plant Root Water Uptake

Background/Question/Methods

As precipitation falls on land, it is redistributed in space and time by land characteristics. In space, gravitational drainage moves water from high to low topographic positions, making valleys wetter. In time, wet-period infiltration is stored in soil pores and rock fractures providing water for plant roots in dry times, and the delay due to hill-to-valley flow makes valleys wet for longer periods. This spatial and temporal redistribution, driven by terrain characteristics, paints a locally different picture of water availability than precipitation alone. In water-limited places and times, this can make a difference for vegetation existence.

Results/Conclusions

Here, based on synthesis of site-based observations and global model simulations, we explore this spatial-temporal redistribution across landscapes and seasons, how the resulting water availability differs from precipitation, how plants may seem to have noticed this difference via root water uptake of soil water originated from precipitation fallen at other places and times, and how such knowledge can advance our understanding of ecosystem dynamics in a changing world.