# Postdoctoral Fellowship: EAR-PF: How does woody plant encroachment alter soil hydrological processes in savanna ecosystems?

> **NSF 01002425DB NSF RESEARCH & RELATED ACTIVIT** · Keen, Rachel M (KS) · $180,000

## Abstract

Dr. Rachel Keen has been awarded an EAR Postdoctoral Fellowship to conduct research and professional development activities under the mentorship of Dr. Pamela Sullivan at Oregon State University. Woody plant encroachment occurs when trees spread in grasslands and savannas. Left unchecked, it can cause these areas to transform into forests. Trees and grasses look and behave very differently. When woody plant encroachment occurs, many changes occur aboveground that are obvious and easy to see. For example, there are more trees but less grass and fewer wildflowers. However, there are many changes occurring underground that are more difficult to see. First, trees take up more water from the soil than grass does. As a result, woody plant encroachment can cause the soil to dry out over time in some places. It can even reduce the amount of water flowing in streams. Trees also have bigger, deeper roots than grass. These roots can change how water moves down into the soil after it rains. Larger roots create channels that allow water to move deep into the soil more quickly. The goal of this project is to better understand how woody plant encroachment changes the amount of water in the soil. To achieve this goal, researchers will study four grassland and savanna sites in South Africa. At these sites, researchers will compare the amount of soil water in places covered by grass and nearby places covered by trees. They will then measure how dry the soil gets over time in these places. Soil

## Key facts

- **NSF award ID:** 2403581
- **Awardee organization:** Keen, Rachel M (KS)
- **PI:** Rachel M Keen
- **Primary program:** 01002425DB NSF RESEARCH & RELATED ACTIVIT
- **All programs:** POSTDOCTORAL FELLOWSHIPS
- **Estimated total:** $180,000
- **Funds obligated:** $180,000
- **Transaction type:** Fellowship Award
- **Period:** 06/01/2025 → 05/31/2027

## Primary source

NSF Award Search: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2403581

## Citation

> US National Science Foundation, Award 2403581, Postdoctoral Fellowship: EAR-PF: How does woody plant encroachment alter soil hydrological processes in savanna ecosystems?. Retrieved via AI Analytics 2026-06-08 from https://api.ai-analytics.org/grant/nsf/2403581. Licensed CC0.

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