How you can help pollinators and urban biodiversity if you let your leaf litter be.
I take issue with the expression ‘dead leaves.’ In my native Polish, leaves that have fallen to the ground are called ‘zwiędłe liście,’ meaning wilted leaves. It is not a matter of semantics alone: those leaves are truly not dead. They host plenty of life within them, and continue to provide invaluable ecosystem services as they pass from one stage of being (green, rustling, shade-providing) to the next (colorful, crunchy, and nutritious).
Nature knows no waste, and fallen leaves can be a valuable resource for the next season if managed well. Fallen leaves, sometimes known as ‘duff’, become mulch as they break down, providing winter ground protection and nutrition to your soil. They also insulate tender plants such as young trees and act as a weed suppressant. Second, leaf piles provide shelter to butterfly, firefly, and moth adults and pupae, who need a winter home as they cannot generate body heat to survive as mammals can. Third, spiders and ladybugs which feed on pests such as aphids also live in the leaves - removing one removes the other and disrupts the ecosystem balance, increasing the need for industrial man-made pesticides. Completing the cycle of usefulness is the role of leaf matter as a source of food for birds; they forage for invertebrates in the time of dearth of nectar, pollen, or fruit.
Can we leave leaves be in a city park or a small urban yard? In the context of urban landscaping, there exist considerations beyond nature itself. City landscapes are by and large highly managed, assuming significant human intervention in the life cycle of vegetation. Parks coexists with built environment and busy street infrastructure, and tree debris has to be cleared off sidewalks and storm drains. But, if we want to sustain the nature that sustains us, we should know how our interventions such as wholesale leaf collection affect the city’s biome. Creating a dedicated space to collect leaves in a small park, or leaving some leaves undisturbed on the ground in larger parks can go a long way in sustaining biodiversity and protecting pollinators as they winter.
Simply put, if we want to see lightning bugs in June, we have to preserve the environment that allows them to survive a city winter.