Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses

Abstract Whitebark pine (Pinus albicaulis) is an important component of high‐elevation ecosystems throughout the northern Rocky Mountains; however, the species was recently listed as “threatened” under the Endangered Species Act due to widespread mortality throughout its native range. Land managers...

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Main Authors: Nickolas E. Kichas, Erin K. Shanahan, Sharon M. Hood
Format: Article
Language:English
Published: Wiley 2024-12-01
Series:Ecosphere
Subjects:
Online Access:https://doi.org/10.1002/ecs2.70099
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author Nickolas E. Kichas
Erin K. Shanahan
Sharon M. Hood
author_facet Nickolas E. Kichas
Erin K. Shanahan
Sharon M. Hood
author_sort Nickolas E. Kichas
collection DOAJ
description Abstract Whitebark pine (Pinus albicaulis) is an important component of high‐elevation ecosystems throughout the northern Rocky Mountains; however, the species was recently listed as “threatened” under the Endangered Species Act due to widespread mortality throughout its native range. Land managers tasked with whitebark pine conservation and restoration require information on strategies that can positively influence whitebark pine establishment and promote growth and defense of preexisting trees on the landscape. Our study investigated the response of whitebark pine tree growth and resin duct defenses to thinning and removal of competing shade‐tolerant conifers in the Caribou‐Targhee National Forest, Idaho, USA. In the nine years following thinning treatments, we found that whitebark pine trees (>12.7 cm diameter at breast height [dbh]) responded favorably to thinning and experienced a 60% increase in basal area increment (52% increase in ring width index) while also producing 34% more resin ducts. Additionally, resin ducts were 23% larger with 49% increased area in the nine years post‐thinning compared with trees in the control. Small diameter (<5 cm dbh) whitebark pine in the treatment experienced a dramatic growth release with over 90% increase in basal area increment (74% increase in ring width index). Thinning also created conditions favorable for whitebark pine seedling and sapling establishment. In the treatment, 75% of seedlings and 93% of saplings were whitebark pine, compared with 32% seedlings and 14% saplings in the control. In addition, 93% of overstory trees in the treatment were whitebark pine, compared with 42% in the control. Whitebark pine tree mortality was similar across both the control (26%) and the treatment (25%), indicating that the thinning treatments did not have any adverse impacts on tree mortality. The positive effects of thinning on whitebark pine establishment and tree growth, coupled with the lack of elevated mortality in the treatment, provide strong evidence in support of thinning as a viable silvicultural technique in whitebark pine conservation efforts.
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spelling doaj-art-93a6f6fd94ca467c812d9face739175a2025-01-27T14:51:34ZengWileyEcosphere2150-89252024-12-011512n/an/a10.1002/ecs2.70099Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defensesNickolas E. Kichas0Erin K. Shanahan1Sharon M. Hood2National Park Service, Yellowstone National Park Wyoming USANational Park Service, Northern Rocky Mountain Science Center Bozeman Montana USAU.S. Forest Service, Rocky Mountain Research Station Missoula Montana USAAbstract Whitebark pine (Pinus albicaulis) is an important component of high‐elevation ecosystems throughout the northern Rocky Mountains; however, the species was recently listed as “threatened” under the Endangered Species Act due to widespread mortality throughout its native range. Land managers tasked with whitebark pine conservation and restoration require information on strategies that can positively influence whitebark pine establishment and promote growth and defense of preexisting trees on the landscape. Our study investigated the response of whitebark pine tree growth and resin duct defenses to thinning and removal of competing shade‐tolerant conifers in the Caribou‐Targhee National Forest, Idaho, USA. In the nine years following thinning treatments, we found that whitebark pine trees (>12.7 cm diameter at breast height [dbh]) responded favorably to thinning and experienced a 60% increase in basal area increment (52% increase in ring width index) while also producing 34% more resin ducts. Additionally, resin ducts were 23% larger with 49% increased area in the nine years post‐thinning compared with trees in the control. Small diameter (<5 cm dbh) whitebark pine in the treatment experienced a dramatic growth release with over 90% increase in basal area increment (74% increase in ring width index). Thinning also created conditions favorable for whitebark pine seedling and sapling establishment. In the treatment, 75% of seedlings and 93% of saplings were whitebark pine, compared with 32% seedlings and 14% saplings in the control. In addition, 93% of overstory trees in the treatment were whitebark pine, compared with 42% in the control. Whitebark pine tree mortality was similar across both the control (26%) and the treatment (25%), indicating that the thinning treatments did not have any adverse impacts on tree mortality. The positive effects of thinning on whitebark pine establishment and tree growth, coupled with the lack of elevated mortality in the treatment, provide strong evidence in support of thinning as a viable silvicultural technique in whitebark pine conservation efforts.https://doi.org/10.1002/ecs2.70099competitiondefensegrowth responseresin ductsthinningwhitebark pine
spellingShingle Nickolas E. Kichas
Erin K. Shanahan
Sharon M. Hood
Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
Ecosphere
competition
defense
growth response
resin ducts
thinning
whitebark pine
title Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
title_full Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
title_fullStr Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
title_full_unstemmed Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
title_short Thinning enhances whitebark pine (Pinus albicaulis) growth and resin duct defenses
title_sort thinning enhances whitebark pine pinus albicaulis growth and resin duct defenses
topic competition
defense
growth response
resin ducts
thinning
whitebark pine
url https://doi.org/10.1002/ecs2.70099
work_keys_str_mv AT nickolasekichas thinningenhanceswhitebarkpinepinusalbicaulisgrowthandresinductdefenses
AT erinkshanahan thinningenhanceswhitebarkpinepinusalbicaulisgrowthandresinductdefenses
AT sharonmhood thinningenhanceswhitebarkpinepinusalbicaulisgrowthandresinductdefenses