An integrative strategy for native plant revegetation: Restoring soil, supporting pollinator populations, initiating old-growth trajectories, and developing tribal nursery seed increase capacity

Photo Credit

Photo by Casey Delphia

The Central Oregon Coast Range was formerly dominated by old-growth forests for thousands of years. During the 20th century, most old-growth was converted to intensively managed plantations focused on timber production, which led to iconic species such as the Northern Spotted Owl and Marbled Murrelet becoming endangered. The loss of old-growth in the Coast Range resulted in the Siuslaw National Forest being classified as a Late Successional Reserve with a primary objective of restoring old-growth stature. Now, due to climate change, the Coast Range is further at risk for high severity fires, such as the recent Holiday Farm Fire (>173,000 acres), increasing the need to transition timber-focused plantations to forests with greater resilience. The Siuslaw National Forest does this by thinning stands, but the process creates highly disturbed sites. However, it provides us the opportunity to test and apply novel revegetation techniques to achieve multiple benefits on the landscape.

Timber-focused plantations disrupted the natural succession of native flora, including rare and culturally important species, and their pollinators necessary to promote ecosystem stability. Revegetation can restore this natural succession on disturbed sites and initiate a floral community that supports a natural trajectory toward old-growth characteristics, such as  low density conifers with large limbs and ample understory forbs. Concurrently, revegetation will also support native pollinator populations and their ecosystem services and remediate the decline of listed pollinator species such as the Western Bumble Bee and Oregon Silverspot Butterfly.

Pollinator Partners Across Landscapes is an existing $1.5 million effort by the Siuslaw National Forest to explore restoration of early successional vegetation to improve pollinator habitat and trajectory toward old-growth development. The Siuslaw dedicated stewardship funds from harvest receipts to initiate work in this arena. Because of strong interest from the private sector, Pollinator Partners Across Landscapes is collaborating with the National Council for Air and Stream Improvement to better understand plant- pollinator relationships and pollinator populations across watersheds in the pacific northwest and northern California.

Our research strives to build upon the Pollinator Partners Across Landscapes effort by supporting local tribal nurseries to increase seed supply and use of pollinator-friendly and culturally important native forbs to revegetate disturbed soils on federal, state, and private lands. We will determine the most effective and efficient methods to improve pollinator habitat. such as for bees, butterflies, wasps, flies, hummingbirds, and improve our understanding of the interaction of climate change, plant biochemistry, and pollinator foraging, to support resilient and stable ecosystems. To accomplish these goals, we will collaborate with: 

1. The Confederated Tribes of Grand Ronde 
2. Forest Service collaborators including Siuslaw National Forest, Rocky Mountain Research Station, the Western Center for Native Plant Conservation and Restoration Science, the Region 6 Restoration Team, and the Dorena Genetic Resource Center 
3. Land-grand universities including University of Idaho, Oregon State University, University of Nevada Reno, and University of Maryland Center for Environmental Science

We will first identify important native plants for supporting diverse pollinator populations. We will collect seed from these species from different Coast Range populations to increase genetic diversity and determine appropriate cleaning, storage, quality assessment, and germination treatments. We will work with Confederated Tribes of Grand Ronde to increase seed supply and produce seedlings for our trials. Rising temperatures and drought are key factors implicated in global climate change and accelerate the occurrence of detrimental fire disturbances. Changing conditions likely affect plant biochemistry too. Understanding how native plants respond to these stressors and its effect on their attractiveness to pollinators remains a paramount research question with implications for the success of revegetation efforts. Therefore, we will expose native plant species to varying climate conditions of temperature and drought to test their resilience and health under current and projected climate scenarios. 

Remediation of diminished soil quality, whether through severe wildfire, drought, mining, or from standard harvest practices, is necessary for establishment and implementation success of native plant revegetation. We will explore the use of biochar, a black carbon produced by converting feedstock of slash piles from logging or timber killed by wildfire. Evidence suggests that biochar can suppress invasive weed establishment, decompact soil thus allowing greater water infiltration and retention, and help symbiotic bacteria fix nitrogen, while greatly reducing fire risk and emissions from burning activities. We will test the effectiveness and application rates of biochar for promoting native plant establishment, health, and resilience to climate stressors. 

Pollinators collect nectar and pollen while pollinating flowers, and bees rely solely on these rewards for adult and larval nutrition. Therefore, seed increase is dependent on pollination success by supporting pollinators with rewarding and nutritious plant species. Reward quality is dependent on plant health, which is dependent on soil quality. Therefore, we will determine the principal pollinators of our plant species, and how soil remediation and climate affect floral rewards and attractiveness to diverse pollinators, including threatened and endangered species. Thus, we will determine which environmental conditions and pollinator groups optimize seed set and viability. Finally, because different pollinator species have preferences for different plant species (i.e., no one plant supports all pollinators), we will develop a seed mix for revegetation that balances providing quality nectar and pollen rewards and attracting the highest pollinator diversity. 

As a key product of our work, our research will support the development of protocols to increase seed germination rate, plant establishment, growth, and floral rewards, which is crucial for establishing long-term seed sources of important pollinator hosts for revegetation at a large scale. We will include optimal soil properties that promote plant resilience to climate stress and identify plant species most likely to be successful for long term use in revegetation of pollinator habitat including threatened and endangered species. These protocols will be published as standard operating procedures for nurseries and revegetation contractors in the region, while the framework of our work can be used for seed increase efforts at a broader geographic scale.

 Our project outlines a holistic and integrative research program aiming at developing protocols and standard practices to increase seed production and propagation of native plants to be used in revegetation efforts by optimizing plant health and climate resilience and providing quality rewards to attract and support pollinators. Concurrently, we will sow our seed mix optimized above immediately into application in post-disturbance and post-harvest lands in the Siuslaw National Forest, leveraging our previous Pollinator Partners Across Landscapes project. This revegetation effort will be assessed for implementation effectiveness by monitoring long-term establishment and pollinator attraction. From these results we will enter contracts and agreements with the National Forest System, Tribal, and other non-federal land managers, including remediating mined lands, to implement pollinator habitat revegetation in the Coast Range and provide technical assistance to other regional specific revegetation efforts.

Objectives

Our project addresses the Forest Service’s strategic goals to sustain our nation’s forests, deliver benefits to the public, apply knowledge globally, and excel as a high-performing agency. We will accomplish these goals through our objectives to:

1. Determine the most effective and efficient methods to revegetate disturbed sites intended to improve the trajectory of resilient old growth conditions; 
2. Improve our understanding of the interaction of climate change, plant biochemistry, and pollinator foraging, 
3. Use biochar to ameliorate disturbed soil and improve its recovery, and
4. Collaborate with local tribal nurseries to increase their capacity to supply native seeds and seedlings necessary for our research and revegetation in the Oregon Coast Range.

Expected Project Results

A. Outputs:

1. Optimized plant seed mix for revegetation in Pacific Northwest/Coast Range to support pollinators and pollinator habitat in post-disturbance sites.
2. Develop infrastructure to increase capacity at the Confederated Tribes of Grand Ronde Native Plant Nursery; improved access to native plant seed not currently available in the commercial market.
3. Standard operating procedures for seed propagation of Coast Range pollinator habitat disseminated through workshops, manuals, and publications.

B. Expected Outcomes:

1. Support and advance tribal nursery capacity, infrastructure, and protocols; provide technical assistance for propagation of native seed.
2. Develop standard operating procedures and seed mixes for revegetation of post-disturbance efforts in the Pacific Northwest and Coast Range.
3. Develop and optimize seed increase through plant health and pollination success of key pollinator plant species.
4. Determine the capacity of plant species to attract and support pollinator diversity.
5. Evaluate capacity for revegetating rare, threatened, or endangered plant species, and supporting rare, threatened, and endangered pollinator species.
6. Determine plant species and soil conditions to promote climate change resilient pollinator habitat.
7. Revegetation and propagation of seed mixes on National Forestes post-disturbance land and assess implementation effectiveness.
8. Increased use (and therefore demand for) native plant seed; improved market opportunities for rural community entrepreneurs.

C. Metrics of Success:

1. Revegetation of pollinator habitat to post-disturbance National Forests and tribal lands
2. Forest Service Reports
3. Forest Service Plant Propagation Manuals
4. Extension/stakeholder presentations, workshops, and technical assistance
5. Long-term partnerships with Tribes, Land-Grant Universities, and within the Forest Service
6. Peer-reviewed publications
7. Academic conference presentations
8. Graduate student and post-doctoral research success, and Principle Investigator involvement in graduate committees
9. National Forest early-career scientist long-term research success, networking, and collaborations

Geographies and High-Risk Landscapes to be Addressed

Central Oregon Landscape
Central Oregon Coast Range