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Drought, Meadows, and Climate Change in California’s Sierra Nevada

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By Betsy Harbert

Betsy Harbert is a field team leader on the Earthwatch expedition Restoring Meadows in the Sierra Nevada Mountains and river science project manager at the South Yuba River Citizens League. Despite California’s influx of rain this year, drought is still a real threat. Betsy explains how the research being conducted on this project is critical to understanding potential threats meadow ecosystems face due to climate change.

In Loney Meadow, a 40-acre wet meadow in the northern Sierra Nevada of California, the snow is melting and the water is flowing. New plant growth peaks through the flowing waters, birds awaken and share their song with the quiet landscape. This year, California experienced record precipitation. The water coursing through Loney Meadow offers a respite from the extreme drought stress the meadow has been put through over the previous five years. But the future of this meadow remains in doubt, extreme weather events are expected to continue because of climate change. The potential for the meadow to be resilient to these extreme events, or the meadow’s ability to perpetuate through time, is entwined with the extent of disturbance this meadow has experienced over the last century.

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Plants and animals, including humans, rely on the meadow for a multitude of functions including habitat, food, water filtration and storage, flood attenuation, and carbon storage. These functions have been directly and indirectly degraded by disturbances such as grazing, mining, and logging. The creation and maintenance of a meadow ecosystem is directly tied to its hydrologic regime, defined as the timing and amount of water flow and retention within the meadow. High water tables during the spring and early summer exclude trees and encourage herbaceous plant and woody shrubs adapted to water logged conditions. Soils are often highly productive, resulting in communities of dense sedges, rushes, grasses, and wildflowers. Leaves and litter left behind at the end of the growing season are incorporated as organic matter into the soil which helps sequester carbon and perpetuates the retention of water in the meadow by holding on to water. Thus, the meadow acts like a ‘sponge,’ holding water late into the summer when the surrounding forests are dry. In this way, the meadow is self-sustaining.

Disturbances that disrupt the hydrologic regime of a meadow are often a result of bare soil being exposed. This can happen through historic overgrazing, roads created to access logging or mining sites, or undersized culverts that concentrate water flows through meadows. Once bare soil is exposed, it sets into motion a cycle of erosion that amplifies over time. Erosion increases the capacity of streams so that water courses quickly through the meadow rather than flooding and infiltrating into the meadow to resupply groundwater. This lowers the water table and degrades the ability of the soil to retain water by accelerated decomposition of organic material.

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This matters in times of drought and flooding and everything in between for a degraded meadow. It means that the ground water levels needed to maintain the meadow occur less frequently and for a shorter amount of time. When a degraded meadow floods in extreme years, the erosional force of water only compounds the degradation. The work we do to restore Loney Meadow’s important functions, in collaboration with Earthwatch, is pivotal in creating meadow resiliency in the face of climate change.

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But it is your duty as an inquisitive and thoughtful resident of earth to not take our word for it. This story line means nothing unless we can actually measure the functions we claim these meadows provide.

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In addition, we must demonstrate that our restoration truly leads to improved function and supports a more diverse and dynamic ecosystem. This is where the collaboration with Earthwatch has been critical.

Since 2014, Earthwatch volunteers have helped to collect pre-restoration data at Loney Meadow that characterizes the timing and amount of water moving through, the flora and fauna that live in, and amount of carbon being stored and released. We will measure these same variables post restoration to verify if our hypothesis of increased function as a result of restoration is correct.

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If you are interested in joining us on this important mission, consider signing up for one of our Earthwatch trips this year or next. We are expecting to implement the restoration at Loney Meadow in the fall of 2017 and we continue to collect pre-restoration data on a number of meadows set to be restored in the coming years.

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As we restore more meadows, we increase our impact to broader spatial scales and increase the potential for meadows to provide the important ecosystem functions that we all rely on.

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Discover more by visiting the expedition site at: Restoring Meadows in the Sierra Nevada Mountains.

For questions or comments about this post, please contact us at communications@earthwatch.org.

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