Pollinators and Climate Change

Introduction

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Pollinator populations are declining worldwide due to habitat loss, pesticide use, and climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change . The species that we refer to as pollinators–bees, butterflies, bats, birds, and more–support healthy food chains. In addition to facilitating plant reproduction, including more than 75% of human food crops, pollinators support a wide variety of wildlife species by serving as prey species.

The Sky Island region including southeastern Arizona and northern Mexico hosts an extraordinary diversity of resident and migratory pollinators that are at risk. This region is named for the mountain ranges that in the United States are largely part of the Coronado National Forest. The Sky Island region is nestled in the heart of continental migratory corridors for pollinators and other wildlife, and is undergoing rapid climate change. Some species of native plants are already exhibiting shifts in bloom times and distributions with potential negative consequences for a variety of pollinator species. Changes in climate patterns are creating phenological mismatches between pollinators and the plants they depend on–flowers may not be available when pollinators need them. 

In 2017-2018, Sky Island Alliance (SIA) developed and implemented a climate-informed process for designing restoration projects that will boost resource availability for a diversity of pollinators now and in the future with climate change.

Key Issues Addressed

There is an urgent need to support the animal groups that provide the invaluable ecological service of pollination. As the climate changes, so do the distributions and bloom times of nectar plants. Pollinator distributions and the timing of their need for nectar also change. This can result in insufficient nectar resources for pollinators during their times of need. This mismatch can have cascading effects on ecosystem function, especially for plants and pollinators with specialized relationships. Small changes in restoration practices can increase effectiveness in supporting pollinators, and generate longer-lasting results. 

Loss of ecological functionality along continental and elevational corridors, combined with phenological decoupling of pollinators and their resources (plants that provide nectar, shelter, and larval food), will decrease the capacity of pollinators to adapt to climate change. This project helps migratory pollinators that travel long distances. These pollinators may be particularly at risk to become out of sync with the plants they rely on, because climate change is expected to affect different latitudes in different ways. The elevational gradient that the Sky Island mountains provide can help pollinators move to areas up- or down-slope, if the appropriate floral resources are there to support them.

Efforts in this region to support pollinators can help make a difference. In a time of changing climate, the Sky Islands will become even more important than they already are for pollinators, and the plants and other wildlife that depend on them. SIA’s pollinator-focused restoration in riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian corridors is intended to increase pollinator forage, shelter, and continuity across the landscape while promoting biodiversity and ecosystem function. By focusing on riparian corridors, nectar connectivity can be improved across elevational gradients. The inherent diversity of native plant communities in the riparian understory is an important resource for pollinators. Restoring or enhancing these qualities is expected to be critical to the success of pollinator conservation.

Pollinator-focused restoration can provide ecosystem benefits beyond increased nectar availability. For example, pollinator plants used for restoration provide ground cover and belowground biomass that promote soil stability. Many have seeds or foliage that is eaten by birds and other wildlife. This project creates a new approach to ensure that pollinator conservation is conducted to produce benefits for pollinators and other wildlife both now and into the future as conditions continue to change.

Project Goals

• Establish habitat oases in riparian areas that provide resources needed by pollinators across all seasons
• Employ restoration techniques within migration and elevational corridors that will help species adapt to climate change and support local ecosystems

Project Highlights

Creating Habitat: During the two-year project, SIA cleared over 8 miles of invasive plants from riparian areas and installed 75 pollinator-resource oases, with a total of 4,559 plants of 78 unique species.

• Site Selection: Riparian areas are important for pollinators. If a riparian area was choked with invasive plants, SIA inferred that there were also diminished floral resources. These areas were considered “nectar deficit areas.” Over two years, SIA worked on 10 restoration sites across the region, with the most work done at Bear Canyon in the Santa Catalina Mountains of Coronado National Forest, and at The Nature Conservancy’s Aravaipa Canyon Preserve.
• Existing Floral Resources: To help inform which plant species to use in restoration, SIA began by taking inventory of what floral resources were already at project sites.
• Locally-Adapted Plant Materials: SIA worked with nurseries and volunteers to collect and grow plants with local seed collected within the same watershed as restoration sites. They followed the Bureau of Land Management’s (BLM’s) Seeds of Success protocols for ethical collection. The nurseries cleaned and stored the seed.
• Setting the Stage: With the help of volunteers and partners, SIA removed invasive plants in nectar deficit areas to create space for planting native plants.
• Plant Palettes: Using data from SEINet on species’ elevational distributions and flowering times, SIA developed an analytical approach to identify temporal gaps in pollinator forage. They then focused on augmenting existing floral communities to fill in these gaps with carefully chosen assemblages of flowering plants.
• Pollinator-Resource “Oases”: SIA installed native plants in groupings of multiple plant species to create “habitat oases.” Multiple oases were installed at multiple restoration sites throughout the larger project area.
• Watering During Wet and Dry Times: Staff and volunteers carried buckets of water from streams nearby to water the newly installed plants. During dry times when there was no streamflow or precipitation, they hiked water in using buckets, jugs, and clean backpack sprayers.
• Monitoring Effectiveness: SIA conducted extensive baseline vegetation monitoring, and has continued monitoring installed plants' survival when returning to water them. Potential benefits to pollinators are quantified through the functional traits of the new plants installed.
• Community Engagement: Hands-on seed collection, invasive plant removal, and planting events with volunteers were opportunities to educate the local community about the importance of biodiversity, pollinators, and how they can support pollinators in their own yards. 

Lessons Learned

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For invasive plant control, the team was able to maximize effectiveness while managing environmental sensitivity by combining manual removal and chemical treatments. In Bear Canyon, large groups of volunteers removed dense stands of fountain grass (Pennisetum setaceum) through digging. This eliminated highly flammable biomass and created space for new plantings. Then, they worked with crews to apply aquatic-safe glyphosate to seedlings and plants that were missed. This approach ensured minimal use of herbicide in an environmentally sensitive riparian area, and was more effective than either technique on its own.

In the headwaters of Aravaipa Creek, the team worked on an extensive infestation of invasive vinca (Vinca major) in the riparian understory. After trying hand removal, which was slow, tedious, and demoralizing for volunteers, they shifted their approach to using trained conservation corps crews to treat vinca with foliar application of aquatic-safe glyphosate. In some areas, they clipped it first and applied glyphosate directly to the stems. This was very effective but labor intensive. The improvement was astonishing, both in the scale and effectiveness of the treatment. Re-treatment is still necessary, but bringing the infestation under control is now a task that seems possible. Volunteers were re-engaged with seed collection and outplanting. 

Tightly planted oases concentrate nectar and pollen so that pollinators can use as little energy as possible to get as much energy as possible. It’s also great for humans tending to the new plants, which are easier to find and water if they are close together. Established islands provide a native seed source that helps the site to recover faster as new plants spread into areas cleared of invasives.

It is difficult to monitor and compare direct pollinator use of installed plants unless focusing on one particular pollinator group. There may be a role here for citizen science monitoring, but it was not developed for this project. 

Working with native plant nurseries to collect seed was an effective strategy with several advantages. Nurseries had the appropriate collection permits and ensured that collections were done ethically according to BLM’s Seeds of Success protocols. Source-identified seed allowed SIA to consider the elevation from which the seeds were collected and compare to the elevation of restoration sites, which is important for climate-smart planting. Once collected, nurseries cleaned and stored seeds until they were used for propagation or seed mixes. The team collected more seeds than they used for this project. The surplus is curated with partners and available for other projects.

Land managers can integrate pollinators into their work through simple tweaks to what they are already doing. Examples include restoring riparian areas with native plant species using as many different species as possible.

Next Steps

• Continue to support pollinator communities as a central goal of restoration projects using this climate-smart process
• Create an online tool to share the approach to developing restoration planting palettes
• Work with the Xerces Society to create region-specific Best Management Practices for Pollinator Conservation in both English and Spanish 
• Continue work to install “oases” of pollinator resources along more extensive stretches of Aravaipa Creek while monitoring and maintaining previously installed islands
• Develop Best Management Practices for effective management of vinca in southwestern riparian ecosystems

Funding Partners

• This work was funded in large part by a grant from the Wildlife Conservation Society through the Climate Adaptation Fund; support to establish this fund was provided by the Doris Duke Charitable Foundation. 
• US Forest Service Resource Advisory Committee
• Bureau of Land Management
• US Fish and Wildlife Service Partners for Fish and Wildlife
• National Forest Foundation
• Arizona Department of Fire and Forestry Management
• Friends of Sabino Canyon

Resources

• Article in High Country News
• Sky Island Restoration Cooperative Annual Report 2015
• Sky Island Restoration Cooperative Annual Report 2016
• The Xerces Society Website
• Bureau of Land Management Seeds of Success Protocol
• Pima County Native Plant Nursery Website

Contact

• Carianne Campbell, Strategic Habitat Enhancements, formerly Sky Island Alliance: carianne@strategichabitats.com

Case Study Lead Author

• Amanda Webb, CART Research Specialist, University of Arizona

Suggested Citation

Webb, A., D. (2019). “Helping Pollinators Adapt to Climate Change.” CART. Retrieved from https://www.fws.gov/project/pollinators-and-climate-change.