1. The potential for microbial nutrient cycling processes in urban soils
Microbial processes are important for carbon and nitrogen cycling that underlie soil fertility and pollutant dynamics.
Very little data on urban soils.
The data that we do have suggest that the potential for microbial function is high:
Technosols in green infrastructure.
Urban riparian soils
Lawns
There is potential for developing “super soils” for intensive agriculture and other ecosystem services in urban ecosystems.
Urban soils in a coupled natural human systems context.
Dr. Peter Groffman
Professor of Ecology
CUNY Advanced Science Research Center

2. Microbial biomass and activity in green infrastructure technosols:
Figure 3: Boxplots show the effect of green infrastructure designs: enhanced tree pits (ETP), street-side infiltration swales (SSIS), green street (GS), and vegetation swale (VS), on carbon and nitrogen microbial biomass, microbial respiration, potential net mineralization and nitrification, and denitrification enzyme assay (DEA), respectively. Middle bar is median, box comprises extends from 25% to 75% quartiles and horizontal bar stands for minimum and maximum values. Significant differences are indicated by different letters, P < (n = 12, 15, 33 for ETP, SSIS, and VS, respectively).
Deeb et al. (submitted)

3. Microbial biomass and activity in green infrastructure technosols:
Figure 3: Boxplots show the effect of green infrastructure designs: enhanced tree pits (ETP), street-side infiltration swales (SSIS), green street (GS), and vegetation swale (VS), on carbon and nitrogen microbial biomass, microbial respiration, potential net mineralization and nitrification, and denitrification enzyme assay (DEA), respectively. Middle bar is median, box comprises extends from 25% to 75% quartiles and horizontal bar stands for minimum and maximum values. Significant differences are indicated by different letters, P < (n = 12, 15, 33 for ETP, SSIS, and VS, respectively).
Deeb et al. (submitted)

4. Urbanization results in alteration and loss of wetlands, especially riparian wetlands:
I. Natural Channel
Urban vs. Forested
Storm Hydrograph
Stream
Water Table
II. Channel with Incision
Due to Increased Runoff
Urbanization leads to “Flashier” storm
Flows which incise stream channels.
An important change resulting from urbanization is an increase in impervious surface cover, which affects the hydrology of urban areas. Impervious surfaces increase surface runoff and flood peak discharges and decrease infiltration and groundwater recharge. The engineering of stream channels with channels and storm drainage systems compound the effects of impervious surface cover by directing surface runoff directly into streams. These increased flows have dramatic effects on stream channel geomorphology widening and deepening channels and eroding stream banks (Figure 1). High flows and peaks can also lead to stream scouring, reducing the presence of large woody debris in urban streams. Large woody debris are important to the formation and maintenance of organic debris dams which obstruct stream flow and function as “hot spots” of nutrient cycling in streams. The systematic degradation of urban streams has come to be referred to as “urban stream syndrome” (Walsh et al. 2005).
Channel incision and reduced infiltration in uplands
leads to lower water tables in the riparian zone which
causes wetland to upland soils and vegetation to change
resulting in less filtering of upland derived nitrate.
(Walsh et al. 2005, Figure from

5. Are detention basins the new riparian zone?
Stormwater structures (detention basins) are engineered to mitigate impact of impervious surfaces on stream discharge.
Their impact on nutrients (especially nitrogen) in unclear.
Source: Neil Bettez

6. Can you find the detention basins in this suburban landscape?
½ mile x ¾ mile area
Source: Neil Bettez

7. Can you find the detention basins in this suburban landscape?
½ mile x ¾ mile area
13 structures in 1.25 km x .75 km (1/2 mile x ~ ¾ mile
Source: Neil Bettez

8. Denitrification higher in detention basins than in natural riparian zones:

9. Urban grasslands:
Ecosystems dominated by turf-forming species created and maintained by humans for aesthetic and recreational (not grazing) purposes.
Have coherent patterns of ecosystem processes that can be evaluated with the same approaches used to study other ecosystem types e.g., forests, rangelands, prairies.
163,800 km2 - area three times larger than that of any irrigated crop.
Complex and interesting biogeochemistry, significant potential for nitrogen retention.
Complex and interesting biogeosociochemistry: Tremendous variation in management.

10. More soil (to 1 m) carbon in lawns than forests :
Raciti et al. (2011)

11. C and N accumulating at depth in lawns:
Raciti et al. (2011)

12. Soil C and N accumulating over time in lawns on previously agricultural land:
Raciti et al. (2011)

13. A coupled natural human (CNH) context for urban soils and agriculture:
Groffman, Campbell, Svendson, Cheng (in supplication)

14. We need to build urban soils:
Conclusions:
We need to build urban soils:
Potential for “super soils” for intensive agriculture and other ecosystem services.
We need data on microbial functions in urban soils.
Urban soils and agriculture need to be evaluated in an integrated coupled natural human systems context.