ARCHIVED REPORTS_YEAR SIX (2013) PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4:TREE MONITORING RESULTS ' Year 6 (2012) In Year 6 (2012),tree survivorship was 98 percent(Table 4-1),slightly higher than Year 5 (2011). One Fremont cottonwood tree (out of 49 trees total) (or 2 percent)was recorded as dead in Area B (Appendix A).The small increase in tree survivorship compared to the previous year is a result of one Fremont cottonwood that re-sprouted.The Year 6 (2012) survivorship rate (98 percent) is the highest recorded tree survivorship rate for all six monitoring years (Table 4-1). The average heath and vigor score in Year 6 (2012) is 2.6 (Appendix A). An average health I and vigor score of 2.6 is roughly half-way between the"medium' and"low" ranks. This score is the highest recorded vigor score in all six monitoring years (Table 4-2). Fremont cottonwood continues to have the lowest vigor score (2.5) of all three species in this planting sub area (Appendix A).This is due to "leaf scorch" (blackened tissue at the leaf margin) that results in slightly lower vigor scores for this species (Appendix A). The black willow and box elder trees had slightly higher vigor scores of 2.8 and 3.0,respectively.These two tree species may not be quite as susceptible to higher salinity conditions or nutrient imbalances as the Fremont cottonwoods. , 4.5 Area C Planting Area C is the location of the former groundwater treatment system,and it is ' underlain by engineered fill (Figures 1-3 and 1-4).Within the compacted horizons,soil texture and fertility are very poor. Fifteen Fremont cottonwood and black willow trees were planted in this area. Year 1 (2007) Three Fremont cottonwood trees (or 20 percent) died in this planting area during Year 1 r (2007). The average health and vigor score in 2007 was 1.6,which fell in between the low and"medium' ranks. This was the second lowest health and vigor score of all the planting , areas during Year 1 (2007) monitoring. Year 2 (2008) Survivorship in Year 2(2008) (80 percent) was the same as Year 1 (2007).This planting area ' contained the same three Fremont cottonwoods that died during 2007. These trees were replanted in late November,2008, subsequent to the Year 2 (2008) annual tree monitoring. Survivorship of these replanted trees will be assessed in Year 3 (2009). The average health and vigor score for 2008 was 1;3, slightly lower than the average ' calculated for 2007 (1.6).Health and vigor scores of both species contributed to the decline. This health and vigor score was the lowest of all six sub areas. Year 3 (2009) ' The rate of survivorship in Planting Area C in Year 3 (2009) increased to 93 percent from 80 percent as recorded in both monitoring Years 1 and 2(Table 4-1). One Fremont cottonwood died in Year 3 (2009) (Appendix A) compared to three trees in Years 1 and 2 (2007 and 2008). 4-10