Comparison of Riparian Restoration Vegetation to Remnant Reference Forests Along the Middle Sacramen

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Comparison of Riparian Restoration Vegetation to
Remnant Reference Forests Along the Middle
Sacramento River

• Dr. David M. Wood and Cathy A. Little

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Top Three Ecosystem Attributes to Measure
Restoration Success (SER Primer 2004)

• Similar diversity and community structure in
  comparison with reference sites
• Presence of indigenous species
• Presence of functional groups necessary for
  long-term stability
• (plus six more)

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Reference Condition
high
Success Metric
Unsuccessful restoration?
low
0 1 2 3 4 5 6 7 8
9 10 ?
Years Since Restoration
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Goal of This Study

• How does vegetation in restoration sites compare
  with that of remnant reference stands?
• Species richness and diversity
• Native versus non-native composition
• Overall community composition

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Problems with Reference Stands (Remnant Forest)
along the Middle Sacramento River

• Remnant forests not converted to agriculture for
  a reason
• Exceptionally flood-prone or poorly drained
• Poor soils
• Fragmentation and species loss
• Island biogeographic effect extinction gt
  recolonization
• Competitive pressure from invasives
• Poor representation of higher, drier community
  types and/or late successional communities
• Original herbaceous composition of oak woodland,
  grassland community types is poorly known

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Study Design

• Use equivalent methodology to sample older-age
  restoration sites and remnant forests
• Permanent 20 x 30 m plots
• Basal area (from dbh) and density for trees and
  tall shrubs
• Importance Value (Relative Density Relative
  Basal Area)
• Percent cover for small shrubs, vines, and
  herbaceous species
• Distribute study sites spatially and by community
  type
• River Miles 164-232
• Remnant sites 11 sites, 25 plots
• Restoration sites 7 sites, 27 plots
• Plots stratified over Cottonwood Riparian Forest,
  Mixed Riparian Forest, and Valley Oak Riparian
  Forest (Holland types)

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Patches of reference forest on the Sacramento
River, RM 191.
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Restoration site
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Reference forest, established 1960
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Vegetation sampling in a restoration site
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Species Richness
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Top Ten Native Woody Species Restoration Sites
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Top Ten Native Woody Species Remnant Sites
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Top Ten Native Herbaceous Species Restoration
Sites
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Top Ten Native Herbaceous Species Remnant Sites
Note change of scale from previous slide
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Top native understory species, mugwort, is only 4
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Species Diversity
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Non-metric multidimensional scaling ordination of
study plots
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Top Three Ecosystem Attributes to Measure
Restoration Success (SER Primer 2004)

• Similar diversity and community structure in
  comparison with reference sitesYes, and mostly.
• Diversity and richness similar.
• Arroyo willow greatly over-represented in
  restoration but other woody species are similar.
• Presence of indigenous species--Generally yes.
• Native understory species at low abundance in old
  restoration sites.
• Presence of functional groups necessary for
  long-term stabilityYes and no.
• Oaks established, but black walnut invading
  restoration sites.
• Succession pathway after arroyo willow and
  cottonwood decline is uncertain.

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Thanks

• TNC
• USFWS Sac River Refuge
• DWR
• DFG Wildlife Conservation Board
• Many field assistants, especially
• Gay Ann Silman, Matt Brown, Scott Chamberlain,
  Levi Bateman