Urban Forest Ecosystem Services David J. Nowak US Forest Service Northern Research Station Syracuse, NY
Overview Urban forest benefits Urban forest change Assessing urban forests
What is an Urban Forest?
New York City’s Urban Forest 5.2 million trees (1996) tree of heaven 9,0%
black cherry 8,1%
sweetgum 7,9%
other species 38,4%
northern red oak 7,7% Norway maple 6,0%
red maple 3,6% London planetree 4,1%
black locust 4,7%
white mulberry 5,7% sassafras 4,8%
Tree Cover 19.7% tree cover
Urban Vegetation Benefits (Top 10)
Urban Vegetation Benefits
(10) Oxygen production
Oxygen Production
New York City Urban Forest = 61,000 tons annually Oxygen for 2% of NYC population Value = $0 Wikipedia.org
Urban Vegetation Benefits
(9) Products Oxygen production
NYC Urban Forests ~2 million tons of above ground total dryweight biomass in New York City At 2% annual mortality = 40,000 tons of biomass available per year for products Products: timber, palettes, fiber, chemicals (ethanol) Fruit and nut production $ Value = unknown
Urban Vegetation Benefits
(8) Noise reduction Products: timber, food, fiber, ethanol Oxygen production
$ Value of noise reduction = unknown
Urban Vegetation Benefits
(7) Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
$ Value = unknown
Urban Vegetation Benefits
(6) UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
Trees leaves absorb 95% of UV radiation Value = unknown
Urban Vegetation Benefits
(5) Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
Tree Effect Trees remove carbon through growth NYC = 1.3 million tons of carbon stored ($96 million) NYC = 42,000 tons of carbon sequestered per year ($3 million/yr)
Urban Vegetation Benefits
(4) Water quality improvement Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
NYC Value = $47 million / year
Urban Vegetation Benefits (3) Air quality improvement Water quality improvement Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
Air Pollution Effects Pollution removal (2010) ($99.8 million / yr) PM2.5 = 41 t/yr ($60 million / yr) O3 = 763 t / yr ($35.4 million / yr) PM10* = 544 t / yr ($3.4 million / yr) NO2 = 221 t / yr ($817,000 / yr) SO2 = 77 t / yr ($ 123,000 / yr) CO = 31 t / yr ($41,000 / yr) Acute respiratory Symptom reduction 10,000 incidences / year Mortality reduction PM2.5 = 8 lives / year O3 = 4 lives / year
Urban Vegetation Benefits (2) Socio-economic / Aesthetics Air quality improvement Water quality improvement Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
Aesthetics
$ Value = unknown
Urban Vegetation Benefits (1) Cooler air temperatures / energy effects Socio-economic / Aesthetics Air quality improvement Water quality improvement Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
Air Temperature Cooling
Source: NASA: Bright red = 65oC; Dark green / blue ~ 25oC
Increased air temperatures: + 2–11oF
Maximum: + 20oF
$ value = unknown
Temperature and Smog (LA)
Air Temperature and Power Use
Building Energy Use
11.2 million / year
Urban Vegetation Benefits (NYC) Cooler air temperatures (?) Energy effects ($11.2 million / yr) Socio-economic / Aesthetics (?) Air quality improvement ($99.8 million / yr) Water quality improvement ($47 million / yr) Greenhouse gas reduction ($3 million / yr) UV radiation reduction (?) Wildlife habitat (?) Noise reduction (?) Products: timber, food, fiber, ethanol (?) Oxygen production ($0 / yr) Structural Value = $5.3 billion
Drivers of urban forest change Humans Nature
Forces for Change All combine to affect current and future tree cover Human
Nature
ďƒĄ Tree cover
Tree planting Facilitate regeneration* Species selection (invasive species)* Maintenance* Climate change*
Natural regeneration
ďƒ˘ Tree cover
Tree removals Mowing Pruning Development Vandalism Pollution* Transporting insects/diseases* Climate change*
Insects/disease Old age Fire Storms Drought
* Indirect human effects
Changing Tree Cover in Cities
•2007
•2002
Tree Cover Change
NYC = 20.9% (2004)
Tree Cover Change
NYC = 19.7% (2009)
Tree Cover Change 17 of 20 cities had a significant decrease in tree cover Average tree cover change: -0.27% of city area per year* Nationally, urban tree cover dropping: 0.033% of urban area per year 20,000 acres per year 4.0 million trees per year 16 of 20 cities had a significant increase in impervious cover (e.g., buildings, roads) Average impervious cover change: +0.31% of city area per year* * Excluding New Orleans and Detroit
Climate Change
Species Shifts – Betula papyrifera Current
Future – 3x concentration
Importance Values Iverson and Prasad – Climate Change Tree Atlas http://www.nrs.fs.fed.us/atlas/tree/tree_atlas.html
Assessing Urban Forests
Structure
Function
Value
Leaf Area and Canopy Cover
www.itreetools.org
What is i-Tree? Tools to quantify effects for individual trees or tree populations for any area (urban or rural)
Urban Vegetation Benefits (i-Tree) Cooler air temperatures / energy effects Socio-economic / Aesthetics Air quality improvement Water quality improvement Greenhouse gas reduction UV radiation reduction Wildlife habitat Noise reduction Products: timber, food, fiber, ethanol Oxygen production
What is i-Tree? A suite of tools for forest assessment
Canopy
On-line Mapping tools Google Maps
Local Scale
i-Tree 2nd Generation (3 Flagship Programs)
Field Data
Land / Tree Cover Maps
Projected Development Digital Cover Maps
Regional Scale
Growth / Mortality / Influx rates
i-Tree Eco Schematic Field Data
Species DB (~6,400 spp.)
Location DB (Every US city)
Weather Data
Pollution Data
i-Tree International Issues Field Data
Species DB (~6,400 spp.)
Location DB (Every US city)
Weather Data
Pollution Data
Conclusions: The city landscape is changing Urban trees provide numerous benefits Landscape managers need to understand the effects of trees to help sustain environmental quality and human health in cities
Questions?