What mediates tree mortality during drought in the southern Sierra Nevada

Tarin Paz-Kagan, Philip G. Brodrick, Nicholas R. Vaughn, Adrian J. Das, Nathan L. Stephenson, Koren R. Nydick, Gregory P. Asner

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Severe drought has the potential to cause selective mortality within a forest, thereby inducing shifts in forest species composition. The southern Sierra Nevada foothills and mountains of California have experienced extensive forest dieback due to drought stress and insect outbreak. We used high-fidelity imaging spectroscopy (HiFIS) and light detection and ranging (LiDAR) from the Carnegie Airborne Observatory (CAO) to estimate the effect of forest dieback on species composition in response to drought stress in Sequoia National Park. Our aims were (1) to quantify site-specific conditions that mediate tree mortality along an elevation gradient in the southern Sierra Nevada Mountains, (2) to assess where mortality events have a greater probability of occurring, and (3) to estimate which tree species have a greater likelihood of mortality along the elevation gradient. A series of statistical models were generated to classify species composition and identify tree mortality, and the influences of different environmental factors were spatially quantified and analyzed to assess where mortality events have a greater likelihood of occurring. A higher probability of mortality was observed in the lower portion of the elevation gradient, on southwest- and west-facing slopes, in areas with shallow soils, on shallower slopes, and at greater distances from water. All of these factors are related to site water balance throughout the landscape. Our results also suggest that mortality is species-specific along the elevation gradient, mainly affecting Pinus ponderosa and Pinus lambertiana at lower elevations. Selective mortality within the forest may drive long-term shifts in community composition along the elevation gradient.

Original languageEnglish (US)
Pages (from-to)2443-2457
Number of pages15
JournalEcological Applications
Volume27
Issue number8
DOIs
StatePublished - Dec 2017
Externally publishedYes

Keywords

  • Carnegie Airborne Observatory
  • biodiversity
  • canopy chemistry
  • climate change
  • drought
  • eco-hydrology
  • elevation gradient
  • forest dieback
  • imaging spectroscopy
  • species composition
  • species mapping

ASJC Scopus subject areas

  • Ecology

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