Ponderosa pine planting: a survey of expert knowledge

Gregg, Barney Mull (2021) Ponderosa pine planting: a survey of expert knowledge. Masters thesis, Northern Arizona University.

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Abstract

Ponderosa pine forests in the southwestern US are at risk of conversion to other vegetation types due to slow natural regeneration. Artificial regeneration may be a viable tool to prevent the loss of ponderosa pine forests, but there is insufficient literature to guide effective planting. To address this gap, we interviewed researchers, forest managers, and nursery managers to gather expert knowledge to guide future reforestation projects and identify future research areas. We focused on four themes: seed sources, nursery operations, site preparation, and planting operations. Interviews with nineteen planting experts in the Southwest showed that all respondents knew the origin of their seed sources but had differing views on the appropriate level of site specificity for genetic adaptation. Challenges of ensuring appropriate seed sources included limited seed selection, periodicity of masting species, limited funding, and lack of a seed collection program. In the nursery, use of containerized seedling and treatments was considered by respondents to increase success. Site preparation treatments were used by most respondents but there was no consensus on the effectiveness of specific treatments. When outplanting, tree shelters received mixed reviews. Best planting times also had mixed responses between summer monsoon and fall seasons. Expected mortality was highly variable with 50% being the average. Desired eventual stand density ranged from 15 to 200 trees per acre. Grouped planting designs are increasing in popularity, but a few respondents still use grid designs. The use of nurse structures had positive effects. North and east- facing aspects showed to have greater success in comparison to south and west-facing aspects. Contractors are used and preferred for planting because of their ability to bring in big crews. Short-term budgets limit flexibility of project planning and managers to a short window for reforestation.The results of this study are directly relevant to management of future planting projects and suggest the areas that need more systematic research. Artificial regeneration is a critical tool for addressing the challenges of severe disturbance and warming climate. Expert opinions contribute valuable and timely knowledge for sustaining forest ecosystems in the Southwest.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	artificial regeneration; ponderosa pine; Southwest U.S.); Seed sources; Seedlings; Planting
Subjects:	S Agriculture > SD Forestry
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > School of Forestry
Date Deposited:	25 Feb 2022 20:43
Last Modified:	19 May 2022 08:30
URI:	https://openknowledge.nau.edu/id/eprint/5764

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