Exchanges across land-water-scape boundaries in urban systems: strategies for reducing nitrate pollution

Conservation in urban areas typically focuses on biodiversity and large green spaces. However, opportunities exist throughout urban areas to enhance ecological functions. An important function of urban landscapes is retaining nitrogen thereby reducing nitrate pollution to streams and coastal waters. Control of nonpoint nitrate pollution in urban areas was originally based on the documented importance of riparian zones in agricultural and forested ecosystems. The watershed and boundary frameworks have been used to guide stream research and a riparian conservation strategy to reduce nitrate pollution in urban streams. But is stream restoration and riparian-zone conservation enough? Data from the Baltimore Ecosystem Study and other urban stream research indicate that urban riparian zones do not necessarily prevent nitrate from entering, nor remove nitrate from, streams. Based on this insight, policy makers in Baltimore extended the conservation strategy throughout larger watersheds, attempting to restore functions that no longer took place in riparian boundaries. Two urban revitalization projects are presented as examples aimed at reducing nitrate pollution to stormwater, streams, and the Chesapeake Bay. An adaptive cycle of ecological urban design synthesizes the insights from the watershed and boundary frameworks, from new data, and from the conservation concerns of agencies and local communities. This urban example of conservation based on ameliorating nitrate water pollution extends the initial watershed-boundary approach along three dimensions: 1) from riparian to urban land-water-scapes; 2) from discrete engineering solutions to ecological design approaches; and 3) from structural solutions to inclusion of individual, household, and institutional behavior.

A strategic framework to eco-regionalize Ontario

Ontario is a spatially heterogenous province. Natural resource policies and management plans must therefore address and account for this heterogeneity.An eco-regionalization scheme must possess certain minimum criteria to be effective. These criteria are: 1) an explicit explanation of spatial and temporal scales and variation; 2) a hierarchical construct of eco-regional domains; 3) an explicit quantitative description of the eco-regional domains; and, most importantly, 4) an ability to test a given eco-regional scheme as a hypothesis.This paper describes a hierarchical eco-regional framework (HEF) currently being constructed for Ontario. HEF is based on the scale-specific expression of ecological domain structure (geoclimatological parameters) and function (primary productivity). The approach relies on current advances in ecological hierarchy theory, remote sensing techniques, GIS methodologies, and statistical techniques. When completed, HEF will serve as a hypothesis which may be tested and validated at several different spatial scales.