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United States Department of Agriculture

Agricultural Research Service

Title: Understory Patterns in Cut Western Juniper Woodlands

Authors
item Bates, Jon - OREGON STATE UNIVERSITY
item Miller, Richard - OREGON STATE UNIVERSITY
item Svejcar, Anthony

Submitted to: Great Basin Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 21, 1998
Publication Date: N/A

Interpretive Summary: Western Juniper is a woody rangeland species that has dramatically increased in acreage during the past 100 years and now dominates nearly 8 million acres in the northwestern U.S. The increase has been attributed to climate patterns, overgrazing during the early part of this century, and/or reduced fire frequencies. Western juniper can greatly reduce the abundance and productivity of understory forage species. Livestock producers and federal land managers often cut juniper to restore site productivity, but there is uncertainty as to whether reseeding is necessary. We found that many important forage recover quickly after competition from juniper is removed. If the site has the proper mix of species, even if they were greatly suppressed by juniper competition, seeding will not be necessary for site recovery. These rangeland plant communities can produce adequate cover and forage production without the added cost of reseeding.

Technical Abstract: Western juniper (Juniperus occidentalis spp. occidentalis Hook.) has rapidly encroached into adjacent shrub steepe communities in the Intermountain Northwest during the past 120 years. Cutting juniper is a tool used to restore shrub steppe communities. Understory response following cutting is strongly influenced by plant species composition prior rto treatment. This study assessed distribution patterns of understory plants after the cutting of juniper woodland. Cover, density, and diversity of understory species were compared among interspace, duff, and slash zones in cut woodlands. Understory vegetation in cut woodlands exhibited strong location dependence. Plant cover and density increased in all zones following tree cutting. Slash zones tended to have the lowest overall understory cover and plant density values. Understory species which dominated the duff or interspace zones prior to treatment in 1991 continued to dominate these zones the first two years (1992 and 1993) following juniper cutting. Juniper slash had both positive and negative effects on understory species. Species common to interspaces were reduced in density under juniper slash, although plants that survived or established beneath the slash grew larger than their counterparts in the interspaces. Species that increased in density and cover under slash were plants characteristic of duff zones and whose seeds are typically wind dispersed. Understory species composition in duff and interspace zones after removal of western juniper closely resembled pretreatment floristics.

Last Modified: 10/20/2014
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