PLS 147 Lecture Notes - Lecture 6: Freshwater Marsh, Groundwater Recharge, High Marsh
Tidal Wetlands
Erik Grijalva
Wetlands
●areas where water is present, either at the surface or within the root zone, at least
intermittently
○varying duration. eg 3 weeks - entire year?
●vegetation is predominantly flooding-tolerant
○can see plants specifically adapted to wetland areas even if at that period of the
year it may be try
●soils are waterlogged long enough for oxygen to be depleted for substantial periods of
time (hypoxic)
○no oxygen in the root zone for respiration
Intertidal
●area influenced on a daily basis by the dies
●alternately covered and exposed by the tides
●in CA, twice turing the day plant are exposed to sun/wind/air and then submerged
●estuaries, bays, rivers in proximity to the sea
Mixed Semidiurnal tidal cycle: two tidal cycles per day with different amplitudes
●elevations can vary by meters! or very small eg just 1 foot tidal exchange
very stressful environment
●rapid change in temp
●salinity
●inundation
Tidal Marsh - abiotic characteristics
Wetlands with flooding-tolerant plants and waterlogged soils form in areas that are
●sheltered from waves eg along the edges of bays and rivers
○zonation (transition zones)
■zones are very closely tied to flooding
■small rises in sea level can lead to big influences on wetlands
●in the upper reaches of the intertidal
○Upland, transition, high marsh, marsh plain, low marsh, mudflat/tidal flat, open
water (subtidal)
■mudflats
●lots of things live in them, migratory birds
■ecosystem services
●groundwater recharge, cultural support, carbon sequestration
●flood control, buffering
●wildlife refuge
■heterogeneity of habitat types
●where water can be fresh to saline
○gradient of salinity of freshwater mixing w/ ocean water + how long water stays on
the landscape
■evaporation → salinity
○categories:
○critical influential processes affect tidal wetlands at different scales
■regional
●salinity gradient, inundation patterns, watershed flows, suspended
sediment supply
■landscape-level
●dams, untouched, etc
■site-level
●elevation, drainage, distance from channel can influence salinity,
inundation, salinity, competition between different species
●can find completely different communities in the same area due to
disturbances like storms that quickly change dynamics of that area
Tidal Wetlands in California
●east coast ones are broader and flatter
●in CA, cliffaces, mountain ranges up to the edge of the ocean
○patchy, estuarine, river outlet tidal marsh development
○Elkhorn Slough and SF Bay (the biggie)
○etc
History and land use
●pic: 18,000 years ago
●next pic: interglacial period
○sea level rose and filled up SF valley, pushed into CV to form the delta we see
today
○accelerated w/ climate change and sea level rise
●in 1800s, distribution of SF Bay Wetlands
○development of tidal marsh wetlands in SF Bay
○today, mostly filled for ag or development
●the Delta
○infer that most was freshwater wetland subject to tidal inundation (largest in the
world?)→ now agricultural development
●Widespread changes to tidal marshes statewide
○headwaters dammed and diverted
○drained for agriculture, urban development, or waste dumps
○trophic disruptions
Document Summary
Areas where water is present , either at the surface or within the root zone, at least intermittently. Can see plants specifically adapted to wetland areas even if at that period of the year it may be try. Soils are waterlogged long enough for oxygen to be depleted for substantial periods of time (cid:840)hypoxic(cid:841) No oxygen in the root zone for respiration. Area influenced on a daily basis by the dies. Alternately covered and exposed by the tides. In ca, twice turing the day plant are exposed to sun/wind/air and then submerged. Estuaries, bays, rivers in proximity to the sea. Mixed semidiurnal tidal cycle: two tidal cycles per day with different amplitudes. Elevations can vary by meters! or very small eg just 1 foot tidal exchange very stressful environment. )etlands with flooding-tolerant plants and waterlogged soils form in areas that are. Sheltered from waves eg along the edges of bays and rivers. Zones are very closely tied to flooding.
