Page 13 - Sierra Meadows Strategy

Importance of Meadows: Derived Goods and Services
The Sierra Nevada–Southern Cascade Region is of great signi cance to the State of California. Comprising 25% of California’s total land area, the region is California’s principal water source, playing a critical role in California’s water supply and hydrological system (Sierra Nevada Conservancy 2014). More than 60 percent of California’s developed water supply originates in the Sierra Nevada, serving end users throughout the State2. In addition, the region contains a rich diversity of ecosystems, supporting 50 percent of California’s plant species and 60 percent of California’s animal species2,26,27. The region also provides world class recreational opportunities enjoyed by millions around the world. Healthy meadows are important for local natural resource based economies supporting recreational, tourism, agricultural activities, among others28,29.
Meadows cover less than 2% of the overall Sierra/Cascade landscape, but their unique hydrologic and ecological functions make meadows extraordinarily important. Fully functioning meadows add resiliency to the hydrologic and ecological processes that sustain California’s headwaters, particularly during drought years which experts predict will be more common as climate warms30,31,32. Decreases in snowpack storage are expected to occur in the central Sierra Nevada particularly at mid-level elevations (2000 to 3000 ft. above MSL,33). Many meadows depend upon hydrologic inputs derived directly or indirectly from snowmelt34 and bedrock stored groundwater35 and could therefore, be vulnerable to effects of climate change14. However, the ability of meadows to store water from a variety
of surface or subsurface sources makes them potential high elevation water storage alternatives to snowpack in the mountain landscape. In addition to water, healthy meadows can store roughly 1.5 to 2 times more soil carbon than degraded ones; however, higher carbon storage per unit area occurs in some meadows, such as fens, relative to others36,37.
Healthy meadows can lter out sediment and pollutants, improving downstream water quality. Native meadow sedges have long and dense root and rhizome networks that are inherently resistant to erosion and that help maintain wet soils through much of the summer38,39,40. Healthy mountain meadows support these graminoid communities, while hydrologically altered meadows do not41. Channel banks occupied by sedge species erode much more slowly than channel banks supporting other vegetation38; thus these species help maintain the
integrity and shape of the meadow channel and reduce bank erosion rates. With the smaller channel geometry common to functional meadows, high ows more frequently overtop the banks, allowing for percolation to subsurface storage, sediment and microbial ltering prior to the water re-entering the open channel42,43. By ltering out suspended sediment, healthy riparian vegetation builds stream banks and increase the seasonal quality of water released for downstream ecosystems and human uses44,45,43.
Mountain meadows are key habitats for many Sierran animal species because they provide water and shade availability
during the three to six month dry season, promote lower summer stream temperatures, higher plant productivity, increased insect prey availability, and special vegetation structures such as willow thickets46. Moreover, these ecologically rich oases often occur along riparian corridors, linking meadow to meadow and creating movement pathways across the broader landscape. The health and connectivity of these ecological corridors are critical for maintaining genetic diversity within species since these corridors facilitate interbreeding among populations and because they enable animals and plants to nd new areas to inhabit. In the face of climate change and growing development pressures, these corridors can be lifelines for these species. The Sierra Nevada mountain range includes about two-thirds of the bird
and mammal species and about half the reptiles and amphibians in the State of California46,47. During summer months, montane meadows are considered the single most important habitat in the Sierra Nevada for birds46,47,48. Meadows with streams that ow through them are also important habitat for native trout
and other aquatic species49, but are threatened by widespread warming50.
The formation and maintenance of some mountain meadows may be due in part to actions of beaver (Castor canadensis)51. Beaver dams increase the vertical and lateral connectivity of rivers
and streams, and associated oodplains that include mountain meadows. By raising the water table around dams, beaver increase the productivity of riparian and aquatic vegetation
and help restore habitat for native species dependent upon functional meadows and associated channels. Research from the Rocky Mountains illustrates the role beaver have played over thousands of years in alluvial sediment storage and formation of meadow landscapes and the long-term carbon storage provided by beaver ponds52,53,54. More studies are needed to understand the role of beaver in providing habitat, storing carbon, and providing an alternative approach to meadow restoration.
Meadows occur along a hydrologic continuum ranging from
a) dry meadows, which remain moist or wet in the rooting zone
only for several weeks following snowmelt, to
b) wet meadows, which stay saturated at or near the surface for 1-2 months but can drop to moderate soil moisture levels later
in season, to
c) fens, which typically remain saturated at or near the surface
throughout the entire growing season and support organic soil.
Fens are peat-accumulating wetlands with a steady hydrologic regime, consisting of groundwater ow combined with surface ows such as snowmelt and/or stream ow, that allows them
to remain saturated for most if not all of the growing season.
The groundwater input to fens gives rise to unusual chemistry, which results in a highly diverse and distinct ora dominated by mosses, grasses, and sedges, but which also includes shrubs and trees55,24. In contrast, bogs receive water primarily from precipitation. There are no bogs in California due to its semi-arid climate. These properties de ne existing meadows.
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