By Jennifer Wilson-Pines
Whenever I hear someone dismissing a piece of land as vacant, it makes me nuts. There is land undeveloped for human use, but no vacant land (or water for that matter). Unless the land has been saturated with pesticides, every acre contains billions of soil microorganisms, both flora and fauna.
Plants will colonize cleared land in a predictable succession: grasses, annuals and perennials, then shrubs and small trees and eventually canopy trees. Insects, birds and small animals will make use of the improving habitat. The expression “Nature abhors a vacuum” means unless the land has been too damaged by pesticides or non-permeable surface, plants and animals will reclaim that area.
“Vacant” land has value in services to our environment. Unlike developed parcels, water can percolate into the aquifer uncontaminated by pesticides, herbicides, and other household and business pollutants. Absorption of stormwater also prevents runoff to more sensitive areas and decreases flooding.
“Weeds” provide food and shelter to insects, birds and animals, control erosion by softening rainfall impact, and in the process of photosynthesis produce oxygen and lower local temperature. These plants provide biodiversity lacking in urban and suburban developed environments.
Several studies of undeveloped urban land have placed significant values on those sites. A study in the City of Roanoke, Va., found that trees in vacant land stored almost 100,00 tons of carbon. The value of carbon and pollutant removal and storage was estimated at about $8.5 million.
Some cities have begun to recognize the value of undeveloped land for stormwater management, biodiversity and community greenspace. By using greenspace to store stormwater, this removes pressure on the stormwater drain system and sewage treatment plants. Milwaukee has used vegetated swales and buffers on brownfields to capture stormwater. Philadelphia uses undeveloped parcels as part of its Green City, Clean Waters green stormwater infrastructure plan. Staten Island’s Bluebelt has state permits to manage stormwater. Buffalo found that undeveloped parcels absorbed and infiltrated as much as 50% of annual rainfall.
Philadelphia leads the “rethinking vacant land” movement. Its greening program has found that converting vacant lots into community gardens provides fresh food to underserved communities and a community gathering space in addition to reducing air pollution and promoting community health.
New York City has a Green Thumb program, which is the largest community gardening program in the nation. The Green Thumb program was created to renovate derelict land using volunteers after many parcels were abandoned during the economic downturn in the 1970s. The community gardens provide green spaces in areas without formal parks, improve air quality, contribute bio-diversity and promote the well-being of the community. The Green Thumb program provides technical and material support to over 600 community gardens in the City.
Part of the problem is that zoning codes see plopping a building on land as the highest and best use. Provision is rarely made in code for green space, permeable surfaces and community access. Vacant lot has a negative connotation, bringing up visions of trash strewn, rodent-infested blight.
Zoning can be adopted to allow municipalities to manage abandoned lots as green space. Philadelphia has had great success partnering with the Philadelphia Horticultural Society. Multiple public surveys have shown that citizens are willing to pay for land preservation. All it takes is a shift in perception, a change of zoning codes and the political will to do so.
