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    Author(s): Jianwei ZhangMartin W. Ritchie
    Date: 2008
    Source: In: Deal, R. tech. ed. General Technical Report, PNW-GTR-733. Portland, Oregon, USA. USDA Forest Service, Pacific Northwest Research Station. 306 p.
    Publication Series: General Technical Report (GTR)
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (0 B)


    The ecological research project of interior ponderosa pine forests at the Blacks Mountain Experimental Forest in northeastern California was initiated by an interdisciplinary team of scientists in the early 1990s. The objectives of this study were to determine the effect of stand structure, and prescribed fire on vegetation growth, resilience, and sustainability of ponderosa pine ecosystem. Two stand structures were created with mechanical thinning on 12 units of about 100 hectares each. Low structural diversity (LoD) includes an even spaced, continuous canopy with few snags and few large canopy gaps. In contrast, high structural diversity (HiD) includes many large, old trees with multiple canopy layers, abundant large diameter snags, many small canopy gaps, and some dense clumps of smaller trees. Each structural treatment was randomly assigned in each of three blocks. Each combination (unit) was split into two halves and prescribed fire was applied to one of the split plots after the completion of thinning. Because of the complexity of treatments and large experimental units, thinning and prescribed burns took 5 years to complete. Accordingly, our first post-treatment measurements were staged one year after implementation of prescribed fire. The second post-treatment measurements were completed five years after the initial measurement. In the short term, we found that (1) growth and understory woody plant cover significantly responded to structural diversity, but not prescribed fire; (i) the HiD plots carried much more basal area and stems than low structural diversity (LoD) plots, (ii) both individual and stand-level growth was higher in the LoD plots than in the HiD plots, and (iii) understory woody plant species grew back in five years with higher percentage cover in the LoD than in the HiD, (2) prescribed fire effect was significant for dead woody materials on the forest floor and bark beetle colonization; (i) debris was reduced significantly more with prescribed fire and (ii) bark beetles tended to attack trees weakened by the prescribed fire, (3) by comparing adjacent untreated stands, our HiD treatment appeared to improve health of the largest trees (DBH > 60 cm) in the stand, and (4) no significant interaction was found between structural diversity and prescribed fire. These results suggest that ponderosa pine forests can be treated to enhance stand growth and health without sacrificing understory vegetation diversity and stand productivity in the short-term.

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    Zhang, Jianwei; Ritchie, Martin W. 2008. Restoring eastside ponderosa pine ecosystems at the Blacks Mountain Experimental Forest: a case study. In: Integrated Restoration of Forested Ecosystems to Achieve Multi-Resource Benefits, pp. 107-116. In: Deal, R. tech. ed. General Technical Report, PNW-GTR-733. Portland, Oregon, USA. USDA Forest Service, Pacific Northwest Research Station. 306 p.


    Ecological research, Blacks Mountain, forest restoration

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