Differential Response of Conifers to Drought Across Geographic Gradients

This National Science Foundation Project project will examine how competition, species, and habitat interact to influence conifer tree responses to drought. This research will explore the impacts of drought in order to improve management efforts to mitigate conifer die-back and wildfire risk. Since 2010, over 52 million hectares of trees have died in California's forests due to climate change, drought, and drought-induced disturbances such as wildfire. Forest loss and wildfire trends have important implications for the health, safety, and well-being of communities in both urban and rural areas throughout the American West. The effects of how competition, species, and habitat interact geographically to influence tree responses to drought will be studied across six conifer species. This research will benefit society by providing valuable input data for potential fire risk modeling. The project will also mentor young scientists at an undergraduate institution. It will provide knowledge to land managers and regional tribes through public and educational outreach.

This study will use the recent drought as a natural experiment to investigate conifer responses within diverse species' biogeographic distributions. The project will examine 1) how competition, species, and habitat interact to influence tree responses to drought, and 2) how drought resistance varies among diverse conifer species after years of severe drought. This study uses multiple measures of tree response for common and uncommon conifer species. This research will advance the geographic literature on forest drought responses, while also providing opportunities for students to work with an interdisciplinary research team. This study, focused in northern California and southern Oregon, will provide essential information about the potential impacts of ongoing drought to forest species in a biodiverse and culturally important region of the Pacific West. As forest mortality and drought are not issues unique to this region, findings from this work will benefit management efforts in many forest ecosystems, with implications for fire risk, human health and well-being.

The Team

Humboldt State University Research Team

2019 Field Photos

Coring a western white pine.

Taking a tree core with an increment borer.

Scouting in the Klamath Mountains.

Field work in the Klamath Mountains.

Lassen Peak in Lassen Volcanic National Park. 

Principal Investigators

Student Researchers

Graduate Students

  • Wallis Robinson
  • Gabriel Roletti

Undergraduate Lab and Field Assistants

  • Sarah Aguiar
  • Asher Budnik
  • Ian Conway
  • Elizabeth Hinojosa
  • Suzanne Melendez
  • Diana Orozco
  • Brigitte Price
  • Colleen Smith

Professional Consultants