by Brooklyn Bridge Park on Nov 19, 2015
Without a doubt, colorful foliage is the most ubiquitous symbol of fall. People love seeing bright, beautiful leaves so much it drives a seasonal tourism boost in the northeast. Brooklyn Bridge Park, too, receives its fair share of foliage fanciers looking for leaves in the city. Visitors fixated on pretty colors might not consider what happens to the leaves once they fall. If raking leaves is your least favorite part of the season, you’ll be pleased to learn the answer.
According to BBP Horticulture Director Rebecca McMackin, leaves aren’t called leaves for nothing. Wherever possible, our gardeners let leaves lie where they fall since the decomposing leaves add nutrients back to the soil. This nutrient-rich layer of leaves, twigs, and other organic material is known as duff. Trees want their soil to have certain qualities like a favorable pH level, vitamins and minerals, which duff can help provide. Amazingly, trees can adjust the surrounding soil to fit their requirements, given the materials are available, like they are in duff. Allowing them to reuse their leaves is one of the best ways to help trees make their ideal soil.
Some leaves must be removed, though we try to minimize this as much as possible. BBP Gardeners usually clear leaves from ornamental gardens, which are mostly found around park entrances and at the edges of larger planted areas. Additionally, if disease is found, typically in the form of rusts, mildews or pests, the duff will be removed. In the end, more than just BBP’s trees and plants benefit from leaving duff behind- the left leaves also help park wildlife. Many animals, from Mourning Cloak butterflies to bumblebees, overwinter in the duff layer, emerging to pollinate our flowers in the spring. We think a healthy, vibrant park ecosystem makes for happy visitors, too.