Overview

ARS scientists are monitoring juniper management in Cedar Creek
Juniper encroachment reduces herbaceous standing crop, aka available livestock forage, by an average of 83%
Mastication effectively eliminates woody plant cover with no immediate increases in non-native species cover
Forage does not immediately increase following mastication, but surface woody debris sure does.
Transects will be monitored over time to determine:
- Forage recovery
- Woody debris disapperance
- Plant community dynamics
- Juniper recovery and re-treatment timelines

Methods

Study location

Research was conducted in four Public Land Survey System sections administered by the BLM in the Cedar Creek Anticline of eastern Montana (Figure 1). Sampling began ahead of BLM fuels management treatment Phase 4, Phase 5 Timber, and Phase 5.

Figure 1: The four study sections (numerals) with BLM fuel treatment polygons (dark green lines) mapped over tree density from 2023 RAP data. Thin brown lines are roads. Inset: The Cedar Creek project area in eastern Montana.

Study layout

For long-term monitoring of mastication effects, 25 m transects are sampled prior to treatment so deviation and potential recovery from, and eventual degradation back into, the degraded juniper-encroached state can be documented over time. The first transects were established in June 2024 ahead of Phase 4 and Phase 5 Timber treatments (Figure 2).

In June 2025, transects established ahead of Phase 5 treatments were paired with transects in nearby open (unencroached) rangeland (Figure 4). These transects in open range help demonstrate what changes when juniper density increases, and provide a reference to determine how post-mastication ecosystems recover.

In 2025, having re-sampled transects masticated in Phase 4 and comparing pre-Phase 5 juniper stands to open rangeland, an opportunity was created: Combine both types of data to describe not only how juniper encroachment changes rangeland, but show what happens in the first season after mastication.

Figure 2: Sections sampled in 2024 and again in 2025, Before and After mastication treatment, respectively. Left and Center panels: Actual tree cover in RAP in 2023, before sampling, and in 2024, after mastication was conducted; BLM fuels treatment boundaries in green. Right panel: Change in tree cover following mastication, with BLM fuels treatment boundaries in white.

Figure 3: Study transects over ecological sites in sections 12 & 18. These transects were sampled before mastication and 1 yr after. BLM fuels treatment boundaries in white.

Figure 4: Maps of sections in the Space-For-Time comparison sampled in 2025. On the left, ecological sites and BLM fuels treatment polygons. Broken lines define insets on the right, which plot transect locations over RAP tree cover.

Sampling

Four main types of data were collected:

Herbaceous standing crop— Total aboveground herbaceous biomass available to livestock as forage, determined by clipping quadrats and reported as mass/area
Coarse Woody Debris— Ground coverage of woody material, determined by modified Brown’s lines and reported as % of transect covered
Woody plant cover— Canopy and sub-canopy woody plant density, determined by 1 x 25m belt transects and reported as % coverage
Herbaceous and ground coverage– Quadrat-level canopy cover estimates of ground cover, litter, herbaceous plants, and shrubs, determined by Daubenmire canopy cover and reported as % cover

Initial Results

Data from transects

Figure 5: Combined results of the two datasets showing encroachment and mastication effects on transect-level data.

Data from quadrat canopy coverage

Figure 6: Combined results of the two datasets showing encroachment and mastication effects on quadrat-level coverage data, shown as transect-level means.

Data summary

Table of numerical summaries and statistical results. Columns Open, Encroached, and Masticated present group averages for nine variables, followed by the mean difference for each comparison. Column *Stat.diff?* indicates whether the difference is statistically meaningful.
Response	Comparison	Open	Encroached	Masticated	Difference	Stat. diff?
Herbaceous standing crop (t/ac)	Encroached v. Open	0.18	0.03		-0.15	Y
	Masticated v. Encroached		0.04	0.02	-0.02	N
Woody plant cover (%)	Encroached v. Open	0.1	0.7		0.7	Y
	Masticated v. Encroached		0.5	0	-0.44	Y
Coarse woody debris (%)	Encroached v. Open	0.2	1.1		0.9	Y
	Masticated v. Encroached		1.7	61	60	Y
Total non-native cover (%)	Encroached v. Open	21	7		-14	N
	Masticated v. Encroached		5	5.8	0.8	N
Bare ground (%)	Encroached v. Open	21	14		-7	N
	Masticated v. Encroached		27	22	-5.1	N
Herbaceous litter (%)	Encroached v. Open	43	23	-20		Y
	Masticated v. Encroached		31	3.7	-27	Y
Shredded woody debris (%)	Encroached v. Open	4.4	18		14	Y
	Masticated v. Encroached		6.9	75	68	Y
Biological crust (%)	Encroached v. Open	5.1	19		14	N
	Masticated v. Encroached		21	1.8	-19	Y
Standing herbaceous dead (%)	Encroached v. Open	14	3.6		-10	Y
	Masticated v. Encroached		4.9	1.6	-3.3	Y