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Posted on: March 8, 2017

Sycamore Alluvial Woodland Habitat Mapping and Regeneration Study

Sycamore

Sycamore Alluvial Woodland Habitat Mapping and Regeneration Study

The San Francisco Estuary Institute and H.T. Harvey & Associates received a LAG to assess the biotic and abiotic factors that influence sycamore stand health. The sycamore alluvial woodland habitat mapping and regeneration study provides data relevant to the selection of sycamore alluvial woodland stands that represent the best acquisition, restoration, and enhancement opportunities within the Santa Clara Valley Habitat Plan Reserve System.

Results

DISTRIBUTION • In general, the team expected to find a positive relationship between size class and distance

to the primary channel. This is what was found at Pacheco - young trees were most concentrated close to

the channel and in the inner floodplain and primary channel geomorphic zones, and larger, older trees were

found at relative higher densities further from the channel.  At Upper Coyote Creek, this pattern was not observed. This was perhaps due to historic migration of the channel over time. However, the distribution of large trees at Upper Coyote may reflect a historical path of an older channel along the northern edge of the floodplain.


HEALTH • In general, the team expected to find healthier trees in the more dynamic, more flood prone, less hydrologically managed, and more “natural” system at Upper Coyote Creek. More frequent and intense flood events would be expected to promote conditions more conducive to sycamore growth - availability of cobble sediment, removal of anthracnose-infected litter, and thinning of competitor species. This was not definitively supported by all the metrics examined.


REGENERATION • Regeneration at Pacheco Creek followed a predictable pattern of decreased newer growth with greater distance from the channel. Though it was expected that the natural systems  support more regeneration at Upper Coyote Creek, this result was not supported, as Upper Coyote Creek experienced very little recruitment.



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