Wetland Alteration
Seasonal wetlands were relatively common throughout the Stanford Foothills area in the early Ranchero period, but wetland quantity and quality both began to decline rapidly by the mid to late 19th century. Intensive cattle and horse ranching fostered erosion and the sedimenting in of water bodies. The booming human population appropriated much of the surface and subsurface water via diversions and wells and simply filled or drained the majority of extant wetland areas. The only large regional wetlands to persist to present day were those associated with water storage for livestock (i.e. "Lake" Lagunita cattle pond) or people (i.e. fringing wetlands of Searsville and Felt Lake Reservoirs). Owing to their newfound role as long-term reservoirs, many of these wetlands have undergone a major shift from occasionally to perpetually submerged. Year-round water means the accrual of permanent residents. Seasonal wetlands are relatively predator-free and allow frogs, salamanders, and other amphibians to breed, lay eggs, and develop in comparative safety. Most of these resident predators are harmful, non-native species (especially large mouth bass, Louisiana cray fish, and bullfrogs) capable of consuming vast quantities of juvenile fish, amphibians, and reptiles.
Goals
Goal 1: Restore well-functioning seasonal wetlands in the Stanford foothills.
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| California tiger salamander (Ambystoma californiense) |
Given the appropriations of water, altered hydrology, invasions of non-native species, and outright wetland destruction, it is perhaps no surprise that many wetland-dependent organisms are increasingly rare. Once-common plants such as the false Venus' looking glass (Legenere limosa) and animals such as the California tiger salamander (Ambystoma californiense) are now rare or endangered. To recover these populations as well as the variety of functions associated with wetland communities, we need to improve the quality and quantity of seasonal wetlands throughout the foothills landscape.
Goal 2: Improve the science of restoration by critically evaluating our work.
For a variety of reasons, rigorous restoration monitoring is rarely done. This is unfortunate as we have a poor understanding of what works. Forecasting the likelihood a particular restoration approach will produce a system equivalent to our desired community is, at this point, guess work. Improving restoration success therefore requires detailed information about the performance of past and current restorations. We will be monitoring a variety of wetland functions (seed recruitment, salamander use, inundation, etc.) to document the performance of our restored wetlands.
Pond & Stream Restoration
The foothills were ablaze with activity during the summer and fall of 2003. Our focal areas all previously supported some wetland plants and animals, but by all measures the quality of these wetlands were poor; seasonal stream channels were linear and relatively steep-sided and the few existing ponds were small and highly artificial. We began by salvaging 12,000 native wetland plants from the sites in mid-summer when they were dormant. After saving what we could, we removed the remnant vegetation (mostly non-native weeds) and resculpted the topography of each site. Creeks were made wider and more meandering. Deflection points (or creek bends) along these creeks were made robust with log embankments. These deflection points usually serve to direct seasonal flow away from structures (i.e. roads) or into our ponds. Ponds were designed to fill during flood events and retain water on into the spring. We surrounded many of our ponds with partially-buried log piles to facilitate small mammal establishment and provide structural complexity for reptiles and birds. After construction, we spread our latest mix of native perennial grasses across our sites via hydroseeding and covered the region with chopped, sterile rice straw to reduce seed predation and minimize erosion. The last phase of our initial restoration activities - outplanting the thousands of salvaged wetland plants - began in November and continues to date. We are now awaiting continued winter rains and the critters.
Restoration Timeline
- mid-1990's - failed small-scale pond restoration attempts
- 2001 - began hydrologic monitoring of candidate wetland sites
- 2002 - design & planning
- 2003 - restoration began
- 2004 - assessment phase began
Monitoring
Our wetlands began accruing significant water in late December 2003/early January 2004 and initiated the onset of our routine wetland monitoring. While still quite young, several ponds already support abundant invertebrate populations and possess numerous Pacific Tree Frog egg masses and/or tadpoles.
