Dr. Steve M. Raciti

I study the interactions between plants, soils, and ecosystem processes in context of urbanization and global environmental change. The goal of this work is to increase our understanding of how human activities influence ecosystems, while simultaneously driving the development of tools that can inform policy and management decisions.

One branch of this work examines the role of plants and soils in mediating air and water quality. Another branch explores how urbanization drives changes to ecosystem processes, such as carbon and nitrogen cycling, and the consequences at local-to-global scales. And yet another branch focuses on the fate of natural and semi-natural ecosystems embedded within urban and suburban areas.

The nitrogen and carbon cycles are focal points for much of this work.

Nitrogen, in its reactive forms, is a key element limiting plant productivity in terrestrial and aquatic ecosystems. With the discovery of the Haber process in the early 1900's, humans have had the ability to create synthetic nitrogen fertilizers. This discovery fueled a revolution in agricultural production, but has had enormous consequences for the environment. Nitrogen leaching and runoff from agricultural and residential areas threatens the health of rivers, lakes, and coastal ecosystems. Atmospheric nitrogen pollution from vehicles and power plants exacerbates the problem. Together, these forms of nitrogen pollution threaten the safety of the water we drink and (as a smog precursor) the air we breath. We will need a better understanding of nitrogen cycling in rapidly expanding urban ecosystems if we are to manage this pollutant and limit the harm it causes to ecosystems and human health.

Carbon represents energy in natural and human systems. In natural systems, autotrophs (e.g. plants) convert solar energy into carbon-based chemical energy that serves as the base of most food webs. In human systems, we use ancient stores of carbon-based energy (fossil fuels) to heat buildings, propel our vehicles, and generate the power that fuels our economy. However, the rapid release of ancient carbon into the atmosphere is causing profound changes to the systems that regulate Earth's climate. If we are to ensure a prosperous future for human and natural ecosystems, we will need to understand the consequences of these radical changes to the carbon cycle and develop strategies for mitigation and adaptation.