ARCHIVED REPORTS_2010 YEAR 4 PHYTOREMEDIATION TREE MONITORING REPORT

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LSECTION 4:YEAR 4 TREE MONITORING RESULTS Lcombined,plant survivorship in Area A in 2008 was 88 percent, slightly lower than in Year 1 (2007). The average heath and vigor score of 2.4 is slightly lower than that observed in Year 1 (2.6),but this score is still in between"high" and "medium' ranks. This was the highest health and vigor score calculated in 2008. Addition to Area A also had an average health and vigor score of 2.4. i L Year 3 (2009) L As shown in Table 4-1, the tree survivorship rate in this planting area decreased slightly in Year 3 (from 88 percent in Year 2 to 86 percent in Year 3).Three box elder trees,one red willow,and two cottonwood trees died in Year 3 (or 6 out of 42 trees) (Appendix A).All of the box elders were within the higher planting zone,and drought stress may have been a Lcontributing factor. However, the site was subjected to very high winds in mid-October 2009.Two cottonwoods and one red willow were uprooted during this windstorm.One box elder in this general area is presumed dead but this cannot be confirmed because it is not visible beneath the fallen trees. The average heath and vigor score for Area A in Year 3 is 2.5 (Table 4-2). The adjacent L planting area,Addition to Area A,also had an average health and vigor score of 2.5. A score of 2.5 was the highest health and vigor score calculated in Year 3 (2009). Tree health and vigor appear to be relatively stable in this planting area,based on the similarity of scores recorded in Year 1 (2.6),Year 2 (2.4),and Year 3 (2.5) (Table 4-2). Year 4(2010) L The Year 4 (2010)mortality rate in this planting area is 93 percent (Table 4-1). This rate of survivorship is slightly higher than that observed in Year 3 (2009) (86 percent). Three box elders are counted as dead in Year 4 (2010) (Appendix A).Two cottonwoods and one red L willow were uprooted during a windstorm in Year 3 (2009) and were recorded as dead. In Year 4 (2010),these trees resprouted and produced new growth and were counted as live trees.The main stem of these uprooted trees was snapped,and the lateral surviving Lbranches will form a brushy growth habit. The three box elders that are counted as dead in Year 4 (2010) occur beneath a dense cottonwood canopy and it is possible that they are completely shade-suppressed but possess a live root-stock. If an opening in the tree canopy occurs in future years,it is possible that new lateral growth or stump-sprouts could form on these box elders. LThe average heath and vigor score for Area A is 2.5,which corresponds to a rank in between "high" and"medium' (Appendix A). This is the highest score recorded in any of the planting areas in Year 4 (2010).The health and vigor scores for this planting area have L exhibited very little variation during Years 1 through 4,based on the similarity of scores recorded (Table 4-2). 4.2 Addition to Area A This planting area is composed of three distinct planting zones (higher, middle,and lower). LSix species of trees (and a total of 60 trees) were planted in this area. This area was added during plant installation; therefore,this sub area and planting zones are not depicted in Figure 1-3,Planting Plan. This planting area is shown on Figure 1-4, Actual Planting Layout. w { SAD166749/103500001(YEAR4-2010_HOLTTREE_MONITORING_REPORT-FINAL.DOCX) 43