ARCHIVED REPORTS_YEAR SIX (2013) PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4:TREE MONITORING RESULTS recorded as dead in this planting sub area (Appendix A).These two cottonwood trees potentially could re-sprout from the root-stock or produce new lateral growth and this will be checked during future system checks and site visits. ' In Year 6 (2012),the health and vigor score for Area C was 1.9 (Table 4-2).A score of 1.9 is between"low' and"medium".This is the same score as calculated in Year 3 (2009) and ' Year 5 (2011) (Table 4-2). Health and vigor scores in Year 1 (2007) and Year 2 (2008) were slightly lower,1.6 and 1.3,respectively. The heath and vigor scores for trees in this planting sub area have been below 2.0 in all planting years (Table 4-2). The rate of tree growth in Area C is slower than that observed in trees in Areas A,Addition to A,Area AA,and Area B. In Year 6 (2012), a few trees in this planting sub area have reached heights of more than 10 feet,but others,particularly on the south and west sides of the planting sub area,remain short for their age.These portions of the planting sub area may have been the most heavily trafficked and compacted.The health and vigor scores and tree heights in this planting sub area may increase once tree roots extend beyond the engineered fill layer and reach the native soil and groundwater. 4.6 Area D ' The south end of Planting Area D abuts Whiskey Slough Road, and the site gently slopes down to the slough levee at the north end (Figures 1-3 and 1-4).This planting area is ' composed of two distinct planting zones (the middle and the higher planting zones) (Figure 1-3). Fifty trees,composed of four species in roughly equal proportions (box elder, Fremont cottonwood,valley oak, and black willow),were installed in this area. Year 1 (2007) Eleven trees died in Area D (or 22 percent) during Year 1 (2007). Black willow had the highest mortality rate at this site,followed by box elder. One Fremont cottonwood and one valley oak also died. The average percent survivorship in this planting area is 78 percent. In 2007,this was the only planting sub area with a percent survivorship lower than the 80 , percent threshold. The average heath and vigor score was 1.5, about halfway between"low" and "medium' ranks.This health and vigor score was the lowest of all six sub areas. Year 2 (2008) Limited replanting was conducted in Area D during Year 1 (2007)but mortality in Year 2 still remained high in Area D. Nine trees in this planting sub area (or 18 percent) died in Year 2 (2008).Similar to 2007,black willow had the highest mortality rate,followed by box elder. One Fremont cottonwood and one valley oak also died. In 2007, survivorship , dropped below the 80 percent threshold,but it increased slightly to 82 percent,just above the threshold,in Year 2 (2008).The average heath and vigor score was 1.4,about halfway between"low" and"medium" ranks. This health and vigor score was the second lowest of all six sub areas. Year 3 (2009) In Year 3 (2009) ten trees were recorded as dead in Area D (or approximately 20 percent of 50 planted). Black willows continued to have the highest mortality rate (7 trees recorded as dead) at this site.Two box elder and one valley oak also died.The average percent 412 ,