1. Application of trait-based mechanisms to resilience of ecosystem service provision in an arid riparian corridor Moira Hough, David Chan, Christopher Scott, Brian Enquist, Mitchell Pavao-Zuckerman University of Arizona

2. Land-cover approach
1990
2006
Burkhard 2012

3. Trait-based Approach
Response: traits associated with the response of plants to environmental factors such as resources and disturbances
Effect: traits that determine effects of plants on ecosystem functions such as biogeochemical cycling or propensity to disturbance
Suding New Phytologist 2008

4. Key Questions
Should we consider environmental impacts at intraspecific, interspecific, or land-cover type level?
Most research leading to development of these concepts has taken place in alpine grasslands: Is it applicable to arid riparian woodlands?

5. Study Site: San Pedro River
Scott et al 2000
Dry
Wet
Prior work by Dr Stromberg, Wet/Dry/Int Classification of reaches
TNC Wet/Dry Mapping
Intermediate
USGS

6. Hypothesized Framework
Should we consider environmental impacts at intraspecific, interspecific, or land cover type level?
Hypothesized Framework
Driver
Response Trait
Effect Trait
Distance to Perennial Flow
Litter C
13C
Litter N
Leaf C
Water Availability
Leaf Traits
Response: traits associated with the response of plants to environmental factors such as resources and disturbances
Effect: traits that determine effects of plants on ecosystem functions such as biogeochemical cycling or propensity to disturbance
Soil Processes
Leaf N
Depth to Groundwater
SLA
Landscape Position
Soil N
Soil C
SOM

7. Intraspecific & Interspecific Variation
Cottonwood
p=0.001
Willow
p=0.0698
Mesquite
P<0.001
Species mean differences at p=0.05: Salix/Populus vs Tamarix/Prosopis
Non-parametric: Kruskal-walis
Salt Cedar
P<0.001
p<0.05

8. Land-cover Level Variation
Riparian
p=0.068
Tamarix
P<0.001
Mesquite Bosque
SLA, CN follow similar pattern: change for mesquite but not riparian or tam
P<0.001
*Different at p<0.05 *

9. What is the relevant level of analysis?
Driver
Response Trait
Effect Trait
Intraspecific
Interspecific
Land-cover
Interspecific
Water Availability
Leaf Traits
Soil Processes
Add diagram showing intra, inter, land cover

10. Observed Relationships
Driver
Response Trait
Effect Trait
Litter C
Distance to Perennial Flow
13C
Leaf C
Litter N r²=0.77
Water Availability
Leaf economics
Leaf N
Depth to Groundwater
Soil C r²=0.85
Soil N r²=0.5431
Landscape Position
SLA
SOM r²=0.402

11. Hypothesized Framework
Driver
Response
Effect
Distance to Perennial Flow
Litter C
13C
Leaf C
Litter N
Water Availability
Leaf Traits
Soil Processes
Leaf N
Depth to Groundwater
SLA
Landscape Position
Soil N
Soil C
Response: traits associated with the response of plants to environmental factors such as resources and disturbances
Effect: traits that determine effects of plants on ecosystem functions such as biogeochemical cycling or propensity to disturbance
SOM
Operationally:
Response traits alter when environmental conditions change
Effect traits change ecosystem processes/properties when they are altered

12. Conclusions
At what scale should we consider impacts of environmental change?
Regional species means may be ideal for predicting trait effects on ecosystems
Most research leading to development of these concepts has taken place in alpine grasslands: Is it applicable to arid riparian woodlands?
Yes: Traits do seem to be related to soil properties, BUT…
No because we need to look at the responses of specific species because they have such dominance that they become very important!

13. Which traits?

14. Implications for Resistance/Resilience
Driver
Response
Effect
Distance to Perennial Flow
Litter C
13C
Leaf C
Litter N
Water Availability
Leaf economics
Soil Processes
Leaf N
Depth to Groundwater
SLA
Soil N
Landscape Position
Soil C
Response: traits associated with the response of plants to environmental factors such as resources and disturbances
Effect: traits that determine effects of plants on ecosystem functions such as biogeochemical cycling or propensity to disturbance
Resistance
SOM
Resilience?
Carbon Storage
Nutrient Cycling
Ecosystem Services
Values & Human Use

15. Questions