ARCHIVED REPORTS 2011 YEAR 5 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4:YEAR 5 TREE MONITORING RESULTS i Despite the small increase in the health and vigor score in 2010, the trees within this planting area remain short for their age and it is likely that the roots are still confined to the engineered fill zone.Tree growth and health and vigor scores may increase once tree roots , extend beyond this compacted layer. Year 5 (2011) ' The rate of survivorship in Area C in Year 5 (2011) is 87 percent(Table 4-1), slightly lower than the rate calculated in Year 4 (2010). Two Fremont cottonwood trees were recorded as ' dead in Year 5 (2011). These trees potentially could re-sprout from the root-stock and this will be checked during future system checks and site visits. In Year 5 (2011), the health and vigor score for Area C was 1.9 (Table 4-2).This is a slight decrease compared with the Year 4 (2010) score of 2.2 (Appendix A). A score of 1.9 is between"low' and "medium'. The heath and vigor scores for trees within this planting sub area in Years 1 (2007),2 (2008), and 3 (2009) were also below a rank of 2 (Table 4-2). The rate of tree growth in Area C is much slower than that observed in trees in Areas A, Addition to A,Area AA, and Area B. In Area C,the trees are short for their age, and it is likely that the roots are still confined to the engineered fill zone. Tree growth and health and vigor scores may increase once tree roots extend beyond this compacted 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. 410 SAC/420307/113570001(YEAR5-2011 HOLTTREE MON)TORING_REPORT-FINAL.000X) ,