ARCHIVED REPORTS 2009 YEAR 3 PHYTOEMEDIATION TREE MONITORING REPORT

Home Browse Search

SECTION 5:SUMMARY AND RECOMMENDATIONS ' • Continue to Wean trees from Irrigation in Areas A,Addition to Area A,and Area B. Tree height was not measured in these planting areas,but subjective estimates of tree height suggest that many trees approach or exceed 20 feet. Photographs of trees in these ' areas are provided in Appendix B. It is likely that the root systems of these trees are tapped into the local groundwater or are within the saturated zone,making continued watering in this area unnecessary. Irrigation lines to the large cottonwood and willow trees were capped in these areas in 2009. The irrigation lines were left in place in case in case irrigation needs to be quickly applied during the summer. • Apply Additional Irrigation for Area C. Two sites (Areas C and D)have poor to very poor soils (soil texture and/or compaction). In the case of Area C, the growing trees must be irrigated until the roots can grow beyond the compacted gravel and soil layer, ' which may take several years. Tree growth and survivorship will be decreased until this occurs. Additional irrigation was applied to these trees in 2009 and should be continued to increase the rate of tree growth in this area. Non-granular fertilizer was also applied in this planting sub area to increase health and vigor,and additional fertilizer may be recommended in the future. • Apply Additional Irrigation for Area D. Tree mortality in Area D is slightly greater on A the slopes closest to Whiskey Slough Road,where groundwater depth is higher,but black willow trees nearby the slough also died. Tree health and vigor scores are higher nearer the slough (in the north part of the site) compared to the upper slopes near the road. Trees within this planting site,particularly the south end of the site,near the road, were given additional irrigation in 2009,but would benefit from additional irrigation ' (both irrigation frequency and total quantity of water) in 2010 and beyond. Irrigation is especially important during the hot summer months. Non-granular fertilizer was also applied to this planting area in 2009 to increase health and vigor and additional fertilizer ' treatments may be recommended in the future. • Continued Maintenance of Cage Supports to Prevent Beaver Damage. Beaver damage resulted in the loss of several trees subsequent to Construction Season 1.Severely damaged trees were replaced during Construction Season 2, and cages and fencing were installed to protect the trees from further browse. During the Year 1 (2007) monitoring,a few of the mesh cages in Planting Areas AA and B were observed to have been"pressed together" towards the trunk of the tree,and evidence of beaver damage was visible to the bark and foliage in some areas. This was due to beavers leaning against the mesh , and reaching into the cage to browse on the vegetation.Rebar cage supports were installed in susceptible areas to protect the trees from beaver browse. Continued maintenance of the cage and cage supports is recommended. ' • Develop Cage Management Strategy. Over the long term, trees are expected to outgrow the cages, and bark will grow into the wire mesh and rebar, damaging and ultimately killing the tree. Beavers will likely continue to browse the trees as long as the site and trees are accessible. Therefore,it is recommended that a cage management strategy be developed. One possible option is to prune the lower branches "up" as the tree grows, so that the lower branches do not grow into the cage. In addition, the wire mesh could ' also be pulled out away from the trunk,and enlarged, to increase the diameter of the cage. In Year 3 (2009),some branches were pruned, and cages were opened up and 52 SAC/166749/PANAGON(YEAR3_2009 HOLTTREE MONITORING-REPORT.DOC)