Understanding naturally occurring pine regen-eration dynamics in response to thinning and burning treat-ments is necessary not only to measure the longevity of the restoration or fuels treatment, but also to assess how well regeneration meets forest sustainability guidelines and whether natural regeneration is sufficient for maintaining a sustainable forest structure and composition. A synthesis review was carried out on the effects of mechanical thinning and prescribed burn treatments on natural pine regenera-tion response in frequent-fire ponderosa pine forests across the western United States. The focus was on site-specific variability in pine regeneration dynamics, temporal trends in regeneration presence and abundance, and response to treatment as described in the current literature using 29 studies that met our evidence-based review protocols. Data showed that the effects of thinning and burning treat-ments on regeneration depended on time since treatment. Mechanical thinning, prescribed burning, and thinning plus burn treatments all increased seedling density, but there was high variability among sites and studies. There were mixed results in the short-term (< 10 years) with both increasing and decreasing regeneration, and a general increase in regen-eration 11 - 20 years post-treatment. Some long-term studies (> 20 years) concluded that stands can return to pre-treat-ment densities in terms of total trees per hectare and forest floor dufflevels when there are no maintenance treatments applied. Several studies showed the average ponderosa pine seedling presence, survival and growth found in today's for-ests to be at a high density; this combined with missed fire cycles could contribute to future fire risk and reduce the efficacy of maintaining fuel reduction goals.

Ecological Restoration Institute,Northern Arizona University,P.O.Box 15017,Flagstaff,AZ 86011-5017,USA

[1]Tzeidle N.Wasserman;Amy E.M.Waltz;John Paul Roccaforte;Judith D.Springer;Joseph E.Crouse-.Natural regeneration responses to thinning and burning treatments in ponderosa pine forests and implications for restoration)[J].林业研究（英文版）,2022(03):741-753

ponderosa,dufflevels

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