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Fact sheet: Long-term herbivore exclusion for recovery of buckbrush populations during restoration of ponderosa pine forests in northern Arizona

Huffman, David W. (2015) Fact sheet: Long-term herbivore exclusion for recovery of buckbrush populations during restoration of ponderosa pine forests in northern Arizona. Other. NAU Ecological Restoration Institute.


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Open conditions created by restoration activities in ponderosa pine (Pinus ponderosa Laws.) forests of
 the American Southwest can lead to increases in
 understory plant productivity but also attract large 
ungulate herbivores. New plant growth stimulated
 by tree thinning and prescribed fire can provide 
greater forage quantity and quality for herbivores,
 but grazing pressure on the recovering understory 
may be high. Some management options during the 
period when understories are recovering include 
excluding herbivores from the site or protecting
 individual plants for a number of years following 
restoration treatments. Short-term protection of
 grazed species may provide opportunity for their
 escape through development of mass or structural 
defenses such as spines or thorns. For example, 
Huffman and Moore (2003) showed that two years 
after forest treatments buckbrush (Ceanothus
fendleri Gray) plants protected from mule deer and Rocky Mountain elk had greater stem number, longer stems, and greater current-year biomass than unprotected plants. In contrast, branches of unprotected plants were heavily browsed and just 8 percent of these plants produced flowers. Herbivory pressure also may be lessened with increasing plant community diversity and as more forage options become available to herbivores. However, it is unclear how long protection of grazed plants is needed. Chancellor et al. (2008) showed that buckbrush plants exposed to herbivores after seven years of protection had similar stem lengths and stem numbers as plants that continued to be protected. Leaf area and leaf biomass, however, were significantly less on the recently exposed plants than on protected plants. In this study, we wanted to determine if long-term protection from herbivores was required to restore buckbrush abundance and potential reproduction after forest restoration treatments that were comprised of tree thinning and prescribed fire Buckbrush is a shrub common in ponderosa pine forests of the southwestern U.S. It is important for soil nutrient budgets, understory structure, and habitat for wildlife. We re-measured buckbrush plots (10.8 ft2 (1 m2) in size) in the following groups: 1) unprotected (never protected from herbivores); 2) short-term protection (exclosures installed in 1999, removed in 2006); and 3) long-term protection (exclosures installed in 1999 and maintained throughout the 12-year study period).

Item Type: Monograph (Other)
Keywords: ERI Library, Fact Sheet,
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
S Agriculture > SD Forestry
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: Research Centers > Ecological Restoration Institute
Date Deposited: 02 Dec 2015 21:38
URI: http://openknowledge.nau.edu/id/eprint/1904

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