ARCHIVED REPORTS 2011 YEAR 5 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4:YEAR 5 TREE MONITORING RESULTS 4.1 Area A Area A supports all three planting zones (lower,middle and higher) and therefore has a high diversity of planted tree species (Figures 1-3 and 1-4).Six species of trees were planted ' in this area. Year 1 (2007) ' The mortality rate in this planting area in Year 1 (2007)was low (Table 4-1).Three box elder trees died in 2007 (3 out of 42 trees) (CH2M HILL 2008). These trees were all located in the higher planting zone where depth to groundwater is greatest. On average,for all six species combined,plant survivorship in Area A was 93 percent in Year 1 (2007).The average heath and vigor score was 2.6,which corresponded to a rank in between"high' and"medium'. Year 2 (2008) The mortality rate in this planting area remained low in Year 2 (12 percent). Four box elder trees and one black willow tree died (or 5 out of 42 trees). All of the box elders were within the higher planting zone,where conditions are driest. The black willow tree was within the lower planting zone, a more mesic part of the planting area. On average,for all species combined,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. Year 3 (2009) 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 contributing 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 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) The Year 4 (2010) survivorship 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 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 SAC/420307I113570001 IYEAR5-2011 HOLTTREE MONITORING_REPORT-FINAL.DOCX) 4-3