Dynamic Soil Properties of Urban Soils in New York City.

Urban soil is a key component of urban ecosystem, because it performs essential functions such as regulation of water flow and quality, carbon storage, reservoir of biodiversity, platform for buildings, and support for food and biomass production. It is involved in many modern urban management issues (e.g. urban agriculture, green infrastructure, urban reforestation, ecosystem restoration and brownfield remediation). In New York City (NYC), USDA-NRCS has been conducting soil survey for five decades and a city-wide soil map at 1:12000 scale will soon be available. To better understand the functioning of urban soils, microbial diversity in relation to dynamic soil properties (DSP) data are being collected in NYC through a collaborative grant to Brooklyn College. These include soils formed in naturally deposited materials (till, outwash) under woodland cover to those formed in human transported materials (HTM) containing high artifact fill (>10%) under managed vegetative cover. Each pedon is described and samples of each horizon are collected for DSP characterization. Topsoil samples from 28 additional sites representing diverse land use types are also collected. The DSP include pH, carbon, trace metals, nutrients, particle-size distribution as well as bulk density and soil respiration. Infiltration rates, soil moisture and vegetation are also documented onsite. Preliminary results revealed the extreme diversity of urban soils in NYC. For example, HTM soils with low artifact content (<10%) under turf cover had equal or greater carbon contents (< 1m) than comparably textured natural soils in woodlands, while HTM soils with high artifact content (>10%) had more than twice that amount, due to high inputs of black carbon. The spatial and temporal microbial variations will be interpreted in the context of DSP, and discussed in terms of functions provided by these urban soils according to the degree of human influence (materials, land uses).