ARCHIVED REPORTS_2010 YEAR 4 PHYTOREMEDIATION TREE MONITORING REPORT

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SECTION 4;YEAR 4 TREE MONITORING RESULTS engineered fill zone.Tree growth and health and vigor scores may increase once tree roots J extend beyond this compacted layer. 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' i and"medium' ranks.This health and vigor score was the lowest of all six sub areas. J Year 2 (2008) Limited replanting was conducted in Area D during Year 1 (2007)but mortality in Year 2 J 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 survivorship in this planting area in Year 3 (2009)was 80 percent,slightly lower than the previous monitoring year (2008) survivorship rate of 82 percent.In 2007,this was the only planting sub area with a percent survivorship lower than the 80 percent threshold. In 2008 and 2009, this site met the 80 percent survivorship goal. However, this site continues to have the highest mortality rate of all six planting areas(Table 4-1). The average heath and vigor score recorded in Year 3 (2009) was 1.7,a little more than halfway between'low" and"medium' ranks.This health and vigor score was the lowest of all six sub areas. Year 4 (2010) This site continues to have the highest mortality rate of all six planting sub areas (Table 4-1), likely a result of poor soils and surface disturbance. In Year 4 (2010),11 trees were recorded as dead in Area D (or approximately 22 percent of the 50 trees planted) (Appendix A).This 4-8 SAC/1667491103500001(YEAR4-2010_HOLTTREE_MONITORING REPORT-FINALDOCX) J