Climate Resilient Forest Restoration

Over the last decade, climate exacerbated weather patterns have devastated California’s wildlands through catastrophic wildfires, widespread and unprecedented pest outbreaks, and severe and prolonged drought, costing nearly $3 billion in climate change liabilities (LA Times 2022). Given the scale and extent of habitat loss due to these multiple threats, the development of resilient approaches that integrate genetic considerations are needed in combination with traditional methods to improve ecosystem restoration outcomes, secure diversity, and local adaptation in wild populations, and maintain California’s status as a biodiversity “hotspot” in the face of environmental uncertainty.

Present-day sugar pine (Pinus lambertiana) populations in the Sierra Nevada clearly demonstrate the impacts of intense climate-driven selection pressures from severe and prolonged drought, bark beetle outbreaks, stand replacing wildfires, and white pine blister rust, warranting innovative and resilient restoration approaches.

Five years of drought and bark beetle outbreaks from 2012-2016 killed more than 126 million trees in California and 72,000 in the Lake Tahoe Basin. This drought resulted in significant mountain pine beetle–mediated mortality in sugar pine populations on the north shore of the Lake Tahoe Basin. Despite these high levels of sugar pine mortality, numerous trees survived. In 2017 cone and seed collections were made from 100 surviving sugar pines throughout the Lake Tahoe Basin.  Our lab conducted important ecological (dendrochronology study retrospectively analyzing water-use efficiency over  90 years) and genetic (common garden experiment) studies of sugar pine that now provide valuable information regarding seed source material for reforestation. 

 This  work provides strong evidence that using local and diverse seed sources can promote forest resiliency and provide a form of “insurance” against climate change. Collections from extant plant populations and individuals that have proved to be resilient to anthropogenic and natural stressors should be prioritized for seed collection. Novel restoration strategies guided by a better understanding of how native plants evolve in response to selective pressures such as drought and pest outbreaks hold the potential to amplify population resiliency to contemporary pressures and stressors and highlights the importance of reforestation strategies using the progeny of local and diverse “survivors”.

The Washington Fire of 2015 destroyed thousands of acres of mixed conifer forests, including a unique population of sugar pine in the Monitor Pass area on the Humboldt-Toiyabe National Forest. In 2014 gene conservation collections were made from sugar pine in the Colorado Hill area to evaluate white pine blister rust (WPBR) resistance. These resistance evaluations showed the major gene for resistance (MGR) frequency of 27.5%. This frequency is exceptionally high in a natural stand, with a rare "RR" genotype in the population. Typically, the major gene segregates and what is commonly found is "Rr".

With more than a decade of ecological and genetic studies to develop resilient reforestation strategies of sugar pine and other 5-needled white pines we have teamed up with GIS experts and specialists to further develop restoration approaches steered by advances in technological and scientific understanding. Such integrated approaches can equip land managers with effective adaptive ecosystem restoration tools to respond to extraordinary changes in forested landscapes and facilitate ecosystem recovery.

Our team is employing remote sensing technologies, advanced algorithms, and machine learning, to develop a model to evaluate survivorship of sugar pine seedlings in mountain pine beetle and wildfire impacted forest stands in the Tahoe Basin and Monitor Pass area. Remote sensing (RS) imagery and high-resolution microtopographic maps will also be used with other geospatial datasets (e.g., soils, drainage patterns) to develop GIS algorithms that identify site conditions (e.g., presence of late-lying snow patches, soil properties, solar radiation, canopy water status, etc.) to select appropriate microsites for planting locally sourced and diverse seed material. 

This project establishes a pipeline that recruits and integrates a diverse and equitable workforce into conservation and forest health-related careers by giving California Conservation Corps (CCC) members applied experience in STEM (e.g., restoration, geographic information systems science, plant sciences, and drone technology). These pipelines are vital to improving our field and training the next generation of forest conservation experts. We will build upon past work and improve project outcomes by strengthening our existing partnership with the CCC – with the goal of fostering a diverse workforce around forestry, restoration, and climate change initiatives as we improve restoration strategies.