ARCHIVED REPORTS_2010 YEAR 4 PHYTOREMEDIATION TREE MONITORING REPORT

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J SECTION 5.SUMMARY AND RECOMMENDATIONS In Year 4 (2010), these four planting sub areas met or exceeded the 80 percent survivorship success criterion.On a site-specific basis,this criterion was not met in Area D in Year 4 i (2010), despite replanting some dead trees in these planting sub areas in 2007 and 2008 and J continued irrigation in Years 3 and 4 (2009 and 2010). The following recommendations are presented to maintain and/or increase percent survivorship and tree heath and vigor in Areas C and D,where site conditions are most challenging. • No Irrigation in Areas A, Addition to Area A,and Area B. Tree height was not measured in these planting areas,but subjective estimates of tree height suggest that many trees approach or exceed 25 feet. Photographs of trees in these areas are provided in Appendix B. It is likely that the root systems of these trees are tapped into the local groundwater or are within the saturated zone,making continued watering in this area unnecessary. Irrigation lines to the trees were capped in these sub areas in 2009.The irrigation lines were left in place in case irrigation needs to be quickly applied during the summer. • Apply Additional Irrigation for Area C.Two sites (Areas C and D) have poor to very poor soils (soil texture,fertility,and/or compaction).In the case of Area C, the growing trees must be irrigated until the roots can grow beyond the compacted gravel and soil layer.Tree growth,health and vigor,and survivorship will be decreased until this occurs. Additional irrigation was applied to these trees in 2010 and should be continued to increase survivorship and the rate of tree growth. Non-granular or other fertilizer should also be applied to this planting sub area in 2011 to increase root growth and health and vigor. • Apply Additional Irrigation for Area D.Tree mortality in Area D is higher on the slopes closest to Whiskey Slough Road,where groundwater depth is higher,but trees close to the slough also died.Tree health and vigor scores are higher nearer the slough (in the north part of the site) compared to the upper slopes near the road.Trees within this planting site,particularly the south end of the site,near the road,will require + additional irrigation (both irrigation frequency and total quantity of water) in 2011. J Irrigation is especially important during the hot summer months. Non-granular or another fertilizer should be applied to the trees in this planting area in 2011 to increase j health and vigor and additional fertilizer treatments may be recommended in the future. J • Continued Maintenance of Cage Supports to Prevent Beaver Damage.Beaver damage resulted in the loss of several trees subsequent to Construction Season 1.Severely damaged trees were replaced during Construction Season 2, and cages and fencing were installed to protect the trees from further browse. During the Year 1 (2007) monitoring,a few of the mesh cages in Planting Areas AA and B were observed to have been"pressed together' towards the trunk of the tree,and evidence of beaver damage was visible to the bark and foliage in some areas.This was due to beavers leaning against the mesh and reaching into the cage to browse on the vegetation. Rebar cage supports were installed in susceptible areas to protect the trees from beaver browse. An active beaver "slide" was observed in one sub area in Years 3 and 4(2009 and 2010) (see photographs in Appendix B) and continued maintenance of the cage and cage supports is recommended. r 5-2 SAC/166749/103500001(YEAR4-2010 HOLTTREE MONITORING REPORT-FINAL.DOCX) r