Contrasting Impacts of Climate and Competition on Large Sugar Pine Growth and Defense in a Fire-Excluded Forest of the Central Sierra Nevada

Andrew Slack,Rosemary Sherriff,Jeffrey Kane,Eric Knapp

doi:10.3390/f8070244

Andrew Slack, Rosemary Sherriff + Show 2 more

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https://doi.org/10.3390/f8070244

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Abstract

Many forest ecosystems with a large pine component in the western United States have experienced environmental stress associated with climate change and increased competition with forest densification in the absence of fire. Information on how changes in climate and competition affect carbon allocation to tree growth and defense is needed to anticipate changes to tree vigor and, ultimately, stand structure. This study retrospectively examined the influence of annual climate and competition measures on the growth and defense of 113 large sugar pines (Pinus lambertiana) in a mixed-conifer forest of the central Sierra Nevada of California. We found that growth in large sugar pine was positively associated with higher January temperatures and lower intraspecific competition. Resin duct size was negatively associated with climatic water deficit and total competition, while resin duct area contrastingly showed a positive relationship with total competition. From 1979 to 2012, the rates of growth increased, while resin duct size decreased. Our results suggest that tree vigor measures can respond differently to climate and competition factors that may lead to separate growth and defense trends over time. Stress associated with warmer temperatures and higher competition may distinctly influence individual tree and stand-level vigor with potential implications for future forest dynamics.

Highlights

The old-growth forests of the western U.S that historically experienced low- to moderate-severity fire are undergoing changes in climate and competition that may affect carbon allocation to growth and defense in trees
This study examined growth and defense relationships with climate and competition in large sugar pine (Pinus lambertiana) in an old-growth, mixed-conifer forest of the central Sierra Nevada
Our suggest that annual carbon to defense structures is not has fixed and that both climate attention

Summary

Introduction

The old-growth forests of the western U.S that historically experienced low- to moderate-severity fire are undergoing changes in climate and competition that may affect carbon allocation to growth and defense in trees. The persistent legacy of fire exclusion practices has substantially increased the stand density in many of these forests [1,2,3], which can cause greater competition for water and other resources [4] These conditions are potentially exacerbated by a warming climate [5] that can further limit water resources and increase tree stress [6]. The combination of these changes in climate and competition can substantially affect tree vigor by impacting tree growth and resin defenses [7,8].

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