Now that the dust has settled on the 2015 Summer Inspection season, Friends of Trees is proud to report the highlights of another successful season of monitoring. The total number of trees planted within the City of Portland during the 2014-15 planting season was 2,737 trees. Of these, 80% (2187) were new street trees and 15% (420) were new yard trees, for a total of 2,607 new trees. Five percent of the trees (130) were planted to replace trees that died from the 2014-15 planting season. The 2,737 trees represent 54 genera and 123 species of trees.
Of the 2675 trees monitored in Portland during the 2014-15 monitoring season (MS-14), a total of 90 trees did not survive their first summer season in the ground. That equates to a mortality rate of 3.3% for the monitored tree set, or a 96.7% survival rate if viewed in a more positive light. This survival rate is slightly higher than last season’s, potentially due to more forgiving weather on planting days as well as the timing of the final tree planting events being scheduled earlier in the season. Those trees that died represent 36 species.
In analyzing the data, we found that many tree species survived very well during their first summer in the ground. Of the 123 species planted, 87 had zero mortality. In addition, some of the species that were planted in great numbers, such as Persian Ironwood (1.1%), Cascara (.7%), and ‘Autumn Gold’ ginkgo (0%), had very low mortality rates.
While we are pleased with the survival rate of the trees planted during the 2014-2015 planting season, we still plan to make adjustments based on lessons learned from this monitoring season. These plans include: improving protocol around maintenance of bare-root stock prior to planting, continuing to monitor stressed species over the next few seasons (though inspection results were encouraging in that regard during MS-15), revisiting our stewardship education effort specifically for those receiving free trees, continuing to send watering postcards during dry winter and spring months, and continuing to carefully monitor weather conditions prior to planting days to determine if it would be best to postpone the plantings.
We are hugely indebted to our cadre of summer inspectors, who did a great job and whose effort is the only reason we’re able to monitor our trees at all. Thank you, friends!