Climate Change, Conservation Science, and Adaptive Management 2

Friday, October 21 at 1:00-2:40 pm, Pine Room

*note alternate instance of this session – Thursday at 1pm

Session Description: Climate change poses novel risks to species, from contributing to changing fire regimes, drought, the spread of invasive species, and influencing shifts in the ranges for native species. This session will focus on climate change through the lens of conservation science, how this impacts management decisions, and how adaptive management is more important now than ever.

Session Chair: Robin Murray (Rincon Consultants, Ventura, CA, USA)

23.1    Prioritizing California Native Plants for Butterfly and Moth Conservation

Christopher T. Cosma (University of California, Riverside, Riverside, CA, USA), Nicole Rafferty (University of California, Riverside, Riverside, CA, USA)

The migratory monarch butterfly—which has captivated generations of people with its perilous annual journey and its special relationship with milkweed—was recently declared endangered by the IUCN. As native habitat is increasingly degraded by climate change, urbanization, herbicides, and other stressors, the monarch’s dependence on its obligate host plant is part of what puts the species at risk. Conservation efforts have revealed that planting milkweed is critical to protect the monarch from extinction in the face of these threats. However, it is time for Lepidoptera conservation in the Western US to move beyond this narrow focus on one species. Hundreds of other Western US butterfly species are in decline, including some even more at risk of extinction than the monarch. Like the monarch, each species requires specific native plants to survive. Here, I analyze interaction data between thousands of butterfly and moth species and their native host and nectar plants to find the right plants for the right places to support entire communities of threatened Lepidoptera in California. I find that relatively few plant species support the majority of Lepidoptera species, that Lepidoptera species use discrete host and nectar plants, and that which plants are the most important varies significantly between California ecoregions and habitat types. I have integrated these analyses into a web application that helps users find the best native host and nectar plants to support butterflies and moths anywhere in California. Future work will incorporate climate change predictions to guide climate-resilient habitat design for Lepidoptera conservation.

23.2    Understory plant species diversity increases with dead tree removal after severe bark beetle and drought-induced tree mortality in Sierra Nevada mixed conifer forests

Rebecca B. Wayman (University of California, Davis)

In an era of increased drought, temperature stress, and resultant fire and insect-induced tree mortality, ecosystem resilience, or the ability of a system to recover from disturbance, is of central importance to forest management decisions. In the Sierra Nevada, over 130 million trees died during the severe drought from 2012-2017, causing concern over the fuel loads available for future wildfire. One approach to managing dead fuels after tree mortality is to cut and remove dead trees, yet the ecological effects are not well documented. Here we compare the management practice of dead tree removal with no removal following severe drought and insect-induced tree mortality in the Sierra Nevada and evaluate the initial effects on understory plant biodiversity. We sampled plant communities from 126 paired plots (22m diameter) spanning 200 miles of the Sierra Nevada. We found that plant species diversity was higher where dead trees were removed, with herb richness contributing most to the increased diversity, followed by a more modest increase in shrub richness. Increasing bare ground was associated with higher plant species richness in untreated plots, but lower richness in treated plots. NMDS ordination revealed that understory plant species composition in treated and untreated plots was highly overlapping. Species identified as significant indicators of treated plots were generally more disturbance-adapted and ruderal than significant indicators of untreated plots. Our results align with research in other western forests that found a near-term increase in understory richness after post-mortality dead tree harvest, but future research is needed to identify longer-term patterns. Ecosystem resilience can be defined differently depending on recovery goals, but our project provides information key to assessing whether recovery goals related to understory vegetation are likely to be met under different post-disturbance management scenarios.

23.3    Transforming Urban Areas with Green Infrastructure/Mimicking Nature with Rain Gardens in San Francisco, CA

Casey dos Santos Allen (San Francisco Public Utilities Commission, Yerba Buena Chapter of CNPS and the Sierra Club)

Thanks in major part to the Clean Water Act more and more municipalities and development areas are using “Green Infrastructure” (GI) to help clean up their local waterways and groundwater and there is a great opportunity to use native plants in these endeavors. Green Infrastructure works! The San Francisco Public Utilities Commission (SFPUC) conducted studies of our rain garden projects to measure the amount of stormwater diverted from the combined sewer system. And in some cases, almost 100% of the stormwater from the drainage area was captured and retained on site. This saves energy and the greenhouse gasses associated with pumping wastewater and the processes for treatment. Future Green Infrastructure projects can and should include native plants. Plants, though not necessarily green colored plants, make up the “Green” in Green Infrastructure. To use the least inputs of time and energy local native plants are ideal and have a wide range of added benefits like providing habitat and food for local insects, birds, reptiles, mammals, amphibians, and even fish and local native plants won’t become invasive. As CNPS’ers we need to advocate for using local Native plants with GI projects.