CCI Papercast: Fall colors and protected areas

Talia: Thank you for joining us today at the Center for Conservation Innovation for Defenders of Wildlife. I’m Defender’s of Wildlife’s Staff Scientist Talia Niederman and I’ll be your host today. It’s a beautiful fall day here in the DMV (District of Columbia, Maryland, and Virginia). If you look outside your window, you might already begin to see the yellows, reds, and oranges of fall. Even if you aren’t in a part of the world where the leaves change color, you can probably imagine the autumn aesthetic that I’m referring to. These fall colors are our subject for today. Temperate deciduous forests are one of the most vibrant biomes on Earth. Their autumn colors pull in visitors from all over. However, they also harbor some of the most heavily populated regions, including here in the United States, and accelerating human modification of landscapes means that we could see these colors fade away from parts of the country. Scientists from Defenders of Wildlife’s Center for Conservation Innovation used GIS and spatial analyses to quantify recent and predicted forest disturbance in each U.S. ecoregion and see how much of these forests already benefit from landscape protections. Today we have Dr. Lindsay Rosa, senior conservation scientist, to tell us more. Welcome Lindsay!

Lindsay: Hello!

Talia: Can you give us a quick overview of what you found?

Lindsay: Of course. Almost all ecoregions saw a steady decline in deciduous forest cover between 1985 and 2016 with some of the top ecoregions for autumn aesthetics being underrepresented in the protected areas network. Under worst-case forecasting scenarios, losses are predicted to continue in some of these vibrant areas. However, environmentally focused scenarios suggest there is still opportunity to reverse deciduous forest loss in some ecoregions. Increasing public exposure to temperate forests may help ensure conservation of more natural areas and preserve the quantity and quality of autumn forest viewing.

Talia: It sounds like there have been some significant declines, but you’re saying that not all is lost?

Lindsay: I am. Accelerating landscape change threatens biodiversity and climate stability worldwide, with significant implications for society through degradation of nature’s benefits to people. The science makes clear that transformative action is needed to address the threats to nature: when people experience and connect with nature they are also more likely to act in ways that benefit the Earth. Connections with nature can happen emotionally, physically, intellectually, and spiritually, but most often, through direct experience. Identifying highly visible environments and understanding past and future changes that people have or will experience is therefore important to understanding one social dimension of conservation. For deciduous temperate forests, this is pretty promising. Although they only cover ~7.5% of Earth’s terrestrial land surface, they are one of the most visible biomes because they harbor some of the most heavily populated and developed regions and draw in lots of visitors.

Host: Why are people to drawn to temperate landscapes?

Lindsay: Well I’m sure that depends on who you ask. About 15% of the tree species in the temperate regions of the world change their leaf color from green to yellow or red in autumn, a percentage that can reach 70% of species in some regions of the US. Deciduous forests are very visible cultural icons. Autumn aesthetic is often described in terms of its “complex”, “reassuring”, and “soothing” qualities, attracting outsiders seeking beauty and relaxation in special landscapes. Continued landscape conversion threatens to reduce the autumn color display directly (i.e., tree removal) or indirectly through increased forest stress, and introduces concerns for reduced future aesthetic values and tourism revenues. Ultimately, fewer visitors to these forests also means fewer opportunities to connect people and nature. Given the importance of temperate forests as a symbol for nature and its beauty, forest conversion is among the most distinct impacts of human activity on the forest environment and aesthetic. That is why we were interested in understanding to what extent each U.S. ecoregion is characterized by deciduous forest and quantifying recent (1984-2016) and predicted (2016-2050) forest disturbance.

Talia: Would you mind telling us a bit more about the methods you used for your research?

Lindsay: We overlapped spatial data layers to estimate temperate forest quantity and losses in each ecoregion. The two main datasets we used here are the National Land Cover Database which identifies land use and land cover for each 30m area of the US. This can help us track changes between 1992 and 2019 for when data are available. We used modeled historical land use to go even further back in time and spatially explicit predictive models to analyze estimated forest losses by 2050. For predicting the future, there is much uncertainty so we looked at two scenarios: the economic-growth scenario which assumes rapid development and population growth and the sustainability scenario which reflects and emphasis on environmental protection. Finally, we used the protected areas database of the US to determine how much of the forest ecosystems are already protected.

Talia: Could you tell us more about what you found?

Lindsay: Fourteen out of 20 contiguous US ecoregions have >1% of their area in deciduous or mixed forest. The ecoregions with the greatest proportion of deciduous forest cover include the Atlantic Highlands in New England (62.0%), the Ozark/Appalachian forests (61.0%), and the mixed wood shield and plains in the upper Midwest (36.9%) (Figure 1a). Cumulatively, we found that just under 55 million acres of deciduous or mixed forest were disturbed between 1985 and 2016 (that’s more than the size of Utah). All ecoregions with deciduous forests incurred losses, but some were more dramatic than others. For the future, deciduous forest cover depended on the scenario: The “economic growth scenario” resulted in higher rates of forest loss due to urban increase, agricultural expansion, and higher demand for forest products. For the top leaf-peeping ecoregions, predicted percent change in forest cover is nearly equivalent to declines from 1985-2016 (Figure 1b). Under the “sustainability scenario,” more than half of the ecoregions would have increasing forest cover by 2050. Generally, highest percent increases would occur in ecoregions with relatively low forest cover.

Ecoregions for which deciduous forests make up at least a quarter of the land cover have anywhere between 2.5% and 22.8% protected areas coverage. Declines in forest cover between 1985 and 2050 (economic-growth scenario) exhibited a strong relationship with protected areas coverage across ecoregions, with ecoregions undergoing greater proportional losses having greater forest area and being more often underrepresented in the protected areas network. Under the ‘sustainability scenario’ ecoregions with higher forest cover, but low representation in the protected areas network will see relatively higher gains in deciduous forest.

Talia: Ok, so what does this all mean?

Lindsay: The top ecoregions for autumn aesthetics are experiencing relatively higher forest losses and are also relatively under-protected. Underrepresentation in the U.S. protected areas network means that temperate forests are susceptible to continued fragmentation and modification. Under worst-case forecasting scenarios, losses are predicted to continue. However, environmentally focused scenarios suggest there is still opportunity to reverse deciduous forest loss in some ecoregions. Extensive temperate forest losses may be changing how people experience nature, such as through the awe inspired by leaf peeping.

Some ecoregions, mostly prairies and plains, may continue to see forest losses regardless of scenario. But for some, like the mixed wood plains (32.5% deciduous/mixed forest cover), which covers regions of the northeastern coast and upper Midwest, human behaviors could mean the difference between continued forest losses or reversal to gains. Models under the sustainability scenario suggest there is still time to reverse declining trends in deciduous forest loss; 21.5% increase in forest cover is projected for the top five forested ecoregions, collectively. Centuries of exploitation demonstrate the resilience of temperate forests, but how much disturbance can be tolerated and what it may mean for forest health and fall colors is still under investigation.

Talia: What can we do?

Lindsay: The large difference in forest loss estimates in the predictions scenarios emphasizes the importance of human approaches to economic growth and sustainability in securing environmental stability. Scenic aesthetic is the most direct and immediate aspect via which people perceive and begin to value landscapes. Visually appealing and healthy ecological landscapes evoke positive emotions and promote the desire to protect such landscapes. Growing opportunities for U.S. conservation could work to forge deeper connections between humans and nature and motivate the public to take protective actions against detrimental environmental changes. In response to current global biodiversity and climate crises, science-driven guidance to protect 30% of global lands and seas by 2030 have made its way into US federal and state policy proposals. These proposals call for achieving more equitable access to public land, nature and a healthy environment for all communities. Given this framework, the potential benefits of protecting deciduous forests is manifold. In addition to preserving the visual aesthetics and spiritual connections that people make during autumn senescence, conserving temperate forests also means protecting many of the U.S.‘s biodiversity hotspots and areas of high carbon potential. Additionally, forest conservation ensures more ecosystems will be more resilient to climate stresses (Xu et al. 2019). Therefore, encouraging the public to experience temperate forest autumn foliage may in turn have broad reaching conservation implications for the future.

Talia: Thank you for sharing this work and to our listeners for joining us. We hope hearing about this research will help encourage more people to participate in conservation efforts. Feel free to get in touch with us with any questions, comments, or ideas, at cci at defenders.org. We’ll see you next time!