Modeling the forest dynamics of the Sierra Nevada under climate change using SORTIE-ND

Emily V Moran,Mélaine Aubry-Kientz,Nikole Vannest

doi:10.1007/s13595-021-01074-z

Abstract

Key messageModel simulation results suggest that forests in the Sierra Nevada mountains of California will tend to increase in density and basal area in the absence of fire over the next century, and that climate change will favor increases in drought-tolerant species.ContextClimate change is projected to intensify the natural summer drought period for Mediterranean-climate forests. Such changes may increase tree mortality, change species interactions and composition, and impact ecosystem services.AimsTo parameterize SORTIE-ND, an individual-based, spatially explicit forest model, for forests in the Sierra Nevada, and to model forest responses to climate change.MethodsWe use 3 downscaled GCM projections (RCP 8.5) to project forest dynamics for 7 sites at different elevations.ResultsBasal area and stem density tended to increase in the absence of fire. Climate change effects differed by species, with more drought-tolerant species such as Jeffrey pine (Pinus jeffreyi A.Murray bis) and black oak (Quercus kelloggii Newb.) exhibiting increases in basal area and/or density.ConclusionIncreasing forest density may favor carbon sequestration but could increase the risk of high-severity fires. Future analyses should include improved parameterization of reproduction and interactions of disturbance with climate effects.

Highlights

Climate change impacts on forests have been a major research focus due to their importance for carbon storage (Oren et al 2001; Bonan 2008; Earles et al 2014) and other crucial functions (Flint et al 2013; Goulden and Bales 2014; Grossiord et al 2014), as well as the concern that long generation times could limit tree responses (Rice and Emery 2003; Aitken and Whitlock 2013)
Ten species were included in our analyses: white fir (Abies concolor (Gordon & Glend.) Lindl. ex Hildebr.; ABCO), red fir (Abies magnifica A.Murray bis; ABMA), incense cedar (Calocedrus decurrens (Torr.)Florin; CADE), lodgepole pine (Pinus contorta Bol.; PICO), Jeffrey pine (P. jeffreyi A.Murray bis; PIJE), sugar pine (Pinus lambertiana; PILA), western white pine (Pinus monticola Douglas ex D.Don; PIMO), ponderosa pine (Pinus ponderosa Douglas ex Lawson; PIPO), canyon live oak (Quercus chrysolepis; QUCH), and California black oak (Q. kelloggii Newb.; QUKE)
In the absence of disturbance, forests in the southern Sierra Nevada would likely increase in stem density and basal area over the coming decades (Figs. 2 & 3), at sites with low current density or high BA

Summary

Introduction

Climate change impacts on forests have been a major research focus due to their importance for carbon storage (Oren et al 2001; Bonan 2008; Earles et al 2014) and other crucial functions (Flint et al 2013; Goulden and Bales 2014; Grossiord et al 2014), as well as the concern that long generation times could limit tree responses (Rice and Emery 2003; Aitken and Whitlock 2013). The forests of the Sierra Nevada mountains in California are adapted to a dry summer/wet. Nikole Vannest, and Mélaine AubryKientz; formal analysis and investigation: Nikole Vannest, Mélaine Aubry-Kientz; writing - original draft preparation: Emily V. Nikole Vannest, and Mélaine Aubry-Kientz; writing - review and editing: Emily V. Nikole Vannest, and Mélaine Aubry-Kientz; funding acquisition: Emily V.

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Conclusion