ARCHIVED REPORTS 2011 YEAR 5 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4:YEAR 5 TREE MONITORING RESULTS ' Year 3 (2009) Tree mortality in this planting area decreased about 10 percent in monitoring Year 3 (2009) , compared to Year 2 (2008) (Table 4-1).Two Fremont cottonwood trees (out of 49 trees) died in this planting area in Year 3 (2009) (Appendix A).The average percent survivorship in this planting area in Year 3 (2009) is 96 percent. The average percent survivorship calculated in , Year 2 (2008) was 86 percent. The percent survivorship in Year 1 (2007)was 90 percent, about six percent lower than Year 3 (2009). The average heath and vigor score in Year 3 (2009) increased from scores of 1.8 and 1.6 in ' Years 1 and 2,respectively,to 2.3 (Table 4-2). A health and vigor score of 2.3 corresponds to a slightly higher than a "medium' rank. ' Year 4 (2010) In Year 4 (2010), two cottonwood trees (out of 49 trees total) (or 4 percent) died in Area B ' (Appendix A).This survivorship rate (96 percent) is the same as the rate calculated in Year 3 (2009) (Table 4-1). Plant survivorship values calculated in Year 1 (2007) and Year 2 (2008) were lower, at 90 and 86 percent, respectively (Table 4-1). The average heath and vigor score in Year 4 (2010) is 2.4 (Appendix A). An average health and vigor score of 2.4 is roughly half-way between"medium" and "low" ranks. This value ' is the highest score calculated for this planting area in any monitoring year (Table 4-2). Higher values were observed this year because the willows and box elders in this planting area were growing more vigorously and had less leaf and bark damage compared to previous years (Appendix A). However, some of the cottonwoods in this planting area had 'leaf scorch' (blackened tissue at the leaf margin) that resulted in a lower health and vigor score. Year 5 (2011) ' In Year 5 (2011), two Fremont cottonwood trees (out of 49 trees total) (or 4 percent) were , recorded as dead in Area B (Appendix A). The survivorship rate (96 percent) is the same as the rate calculated in Year 3 (2009) and Year 4 (2010) (Table 4-1). Plant survivorship values calculated in Year 1 (2007) and Year 2 (2008) were lower, at 90 and 86 percent,respectively (Table 4-1). The average heath and vigor score in Year 5 (2011) is 2.4 (Appendix A). An average health ' and vigor score of 2.4 is roughly half-way between"medium' and 'low" ranks. This value is the same as that calculated for this planting sub area in Year 4 (2010) (Table 4-2). Of the three tree species planted in this area,the Fremont cottonwoods continue to have the lowest vigor score (2.3) primarily due to"leaf scorch' (blackened tissue at the leaf margin) (Appendix A).This damaged foliage resulted in the lower health and vigor score for this species. The black willow and box elder trees both had vigor scores of 2.7,slightly higher ' than the Fremont cottonwood. 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 4-8 SAC/420307/113570001(YEARS 2011 HOLTTREE_MONITORING REPORT-FINAL.DOCX) '