You are here

Juniper Paired Watershed Study - Central Oregon

Investigating plant-soil-water relationships in western juniper (Juniperus occidentalis) woodlands

The connections between upland water sources, groundwater, and downstream valleys influence the amount of water available to multiple ecohydrologic processes that drive many ecosystem services (e.g., forage and water provisioning, water quality, wildlife habitat, recreation, etc.). 

Our long-term ongoing research study in central Oregon has provided critical information regarding vegetation and hydrology interactions in western juniper dominated landscapes.

Project objectives are:

1) Characterize water-plant-soil interactions occurring in previously treated (juniper removed) and untreated watersheds,

2) Determine hydrologic connectivity between upland watersheds and downstream valleys, and;

3) Determine juniper reestablishment effects on ecological and hydrological function ten years after treatment.  

Various instrumentation including weather stations, flumes, groundwater wells, soil moisture, and tree transpiration sensors are being used to collect hydrological data.

Ongoing results:

  • Nearly half (46%) of total annual precipitation is intercepted by juniper canopy cover.
  • Greater streamflow and spring flow levels observed in the treated watershed.  
  • Seasonal soil moisture and aquifer recharge in response to winter precipitation and snowmelt runoff inputs.
  • Greater grass (perennial and annual) and shrub cover observed in the treated watershed.
  • Greater grass cover is positively correlated with changes in soil moisture, whereas juniper cover shows a negative correlation with soil moisture.
  • Strong hydrologic connections between upland watersheds and the valley during the winter/spring season.

Peer-reviewed publications related to this project:

Ecohydrologic connections in semiarid watershed systems of central Oregon USA

The seasonal water balance of western juniper-dominated and sagebrush-dominated watersheds.

A hydrogeologic framework for understanding local groundwater flow dynamics in the southeast Deschutes Basin, Oregon, USA

Overstory-understory vegetation cover and soil water content observations in western juniper woodlands: A paired watershed study in central Oregon, USA

Water use and soil moisture relationships on western juniper trees at different growth stages

Water use by mature and sapling western juniper (Juniperus occidentalis) trees

Ecosystem carbon in relation to woody plant encroachment and control: juniper systems in Oregon, USA

Effects of western juniper (Juniperus occidentalis) control on ecosystem nitrogen stocks in central Oregon, USA

The use of low-altitude uav imagery to assess western juniper density and canopy cover in treated and untreated stands


Ecology and Hydrology of Western Juniper - OSU Range Field Day 2016

The OSU Range Field day featured this 23-year research project being conducted in the heart of juniper country in central Oregon. The event that took place on 28 June 2016 at Brothers, OR included morning presentations on project research findings, followed by a tour to the paired-watershed study site.


This range field special report, which includes contributions from OSU and USDA-ARS researchers, illustrates some of the ecological and hydrological relationships found in western juniper woodlands of eastern Oregon. 

PDF iconEcology and Hydrology of Western Juniper_Special Report_OSU Range Field Day 2016.pdf


United States
Latitude: 43.956832
Longitude: -120.349410


Juniper woodlands