Control of arthropod abundance, richness, and composition in the central Arizona-Phoenix metropolitan area
Author(s):
- Christofer Bang, School of Life Sciences, Arizona State University
- Stanley H. Faeth
- John L. Sabo
Abstract:
There is a demand for mechanistic studies to explore underlying drivers behind observed patterns of biodiversity in urban areas. We describe a two-year field experiment in which we manipulated bottom-up (resource availability) and top-down (bird predation) forces on arthropod communities associated with a native plant, Encelia farinosa, across three landuse types urban, desert remnant, and outlying natural desert in the Phoenix metropolitan area, Arizona, USA. We monitored the trophic structure, richness, and similarity of the arthropod communities on these manipulated plants over a two-year period. We predicted that:(1) increased water resources increase plant productivity, (2) increased productivity increases arthropod abundances, and (3) in the urban habitat, top-down forces are greater than in other habitats and limit arthropod abundances. We also predicted that urban remnant habitats are more similar to urban habitats in terms of arthropod richness and composition. Strong interannual differences due to an unusual cold and dry winter in the first year suppressed plant growth in all but urban habitats, and arthropod abundances in all habitats were severely reduced. In the following year, arthropod abundances in desert and remnant habitats were higher than in urban habitats. Water had positive effects on plant growth and arthropod abundance, but these water effects emerged through complex interactions with habitat type and the presence/absence of cages used to reduce bird predation. Plants grew larger in urban habitats, and phenology also differed between urban and desert habitats. The results from caging suggest that bird predation may not be as important in cities as previously thought, and that arthropods may retard plant growth. As expected, desert communities are strongly bottom-up regulated, but, contrary to predictions, we did not find evidence for strong topdown control in the city. Remnant habitats were intermediate between desert and urban habitats in terms of diversity, richness, evenness, arthropod composition and phenology, with urban habitats generally lowest in terms of diversity, richness, and evenness. Our study shows that control of biodiversity is strongly altered in urban areas, influenced by subtle shifts in topdown and bottom-up controls that are often superseded by climatic variations and habitat type.
Keywords:
Temporal Coverage:
2006-12-31 to 2008-05-31Geographic Coverage:
Geographic Description: NO description providedBounding Coordinates:
Longitude:-113.34 to -111.59
Latitude:+34.01 to +32.91
Contact:
Information Manager, Global Institute of Sustainability, Arizona State University,POB 875402,TEMPE
caplter.data@asu.edu
Methods used in producing this dataset: Show
Data Files (4) :
Tabular: Monthly arthropods samples 2007
Description: Denormalized table of arthropods collected from December 2006 to May 2007, site data and taxon data list included
Temporal Coverage: 2006-12-31 to 2007-05-31
Column | Description | Type | Units |
---|---|---|---|
site_id | Site codes, key is given in the worksheet Sites |
string | |
site_number | Assigned number |
integer | |
name | Location for plot (park, school, or nearest building) |
string | |
habitat_type | Which type of habitat: Urban, Desert or Remnant |
string |
Enumeration:
|
plant_id | Each plant per site was given a number from 1-60 |
integer | |
cage | Plant enclosed with bird netting to exclude birds |
integer |
Enumeration:
|
water | Plants were given three levels of irrigation 2L supplemental water for 30 minutes at 6am and 2pm twice a week (low), four times per week (medium), and daily (high) |
string |
Enumeration:
|
taxon_id | Refers to arthropod taxa identified by Maggie Tseng, ASU, taxa are listed within Taxon worksheet |
integer | |
taxon_name | Refers to the taxon name in the Taxon worksheet, which is based on family and morphospecies |
string | |
order | Assigns each sample to taxonomic order |
string | |
suborder | Assigns each sample to taxonomic suborder. Not all samples were identified to this level, indicated by na. |
string | |
superfamily | Assigns each sample to taxonomic superfamily. Not all samples were identified to this level, indicated by na |
string | |
family | Assigns each sample to taxonomic family. Not all samples were identified to this level, indicated by na. |
string | |
subfamily | Assigns each sample to taxonomic subfamily. Not all samples were identified to this level, indicated by na. |
string | |
genus | Assigns each sample to taxonomic genus. Not all samples were identified to this level, indicated by na. |
string | |
species | Assigns each sample to taxonomic species. Not all samples were identified to this level, indicated by na. |
string | |
guild | Assigns each sample to functional feeding group. |
string | |
comment | Some samples are marked as immature |
string | |
dry_mass | Average weight of one individual arthropod |
double | milligram |
indiv_count | Number of individuals of that morphospecies collected at that plant at that site, at that event |
integer | dimensionless |
sum_biomass | indiv_count x dry_mass |
double | milligram |
Tabular: Monthly arthropod samples 2008
Description: Denormalized table of arthropods collected from December 2007 to May 2008, site data and taxon data list included
Temporal Coverage: 2007-12-31 to 2008-05-31
Column | Description | Type | Units |
---|---|---|---|
site_id | Site codes, key is given in the worksheet Sites |
string | |
site_number | Assigned number |
integer | |
name | Location for plot (park, school, or nearest building) |
string | |
habitat_type | Which type of habitat: Urban, Desert or Remnant |
string |
Enumeration:
|
plant_id | Each plant per site was given a number from 1-60 |
integer | |
treatment_id | Color code for each treatment:R Cage, low water, O No cage, low water, B Cage, medium water, G No cage, medium water, Y Cage, high water, P No cage, high water |
string |
Enumeration:
|
cage | Plant enclosed with bird netting to exclude birds |
integer |
Enumeration:
|
water | Plants were given three levels of irrigation 2L supplemental water for 30 minutes at 6am and 2pm twice a week (low), four times per week (medium), and daily (high) |
string |
Enumeration:
|
month | Name of month for collection |
string | |
month_number | Number of month in sample sequence, starting with December as #1 |
integer | |
taxon_id | Refers to arthropod taxa identified by Maggie Tseng, ASU, taxa are listed within Taxon worksheet |
integer | |
taxon_name | Refers to the taxon name in the Taxon worksheet, which is based on family and morphospecies |
string | |
order | Assigns each sample to taxonomic order |
string | |
suborder | Assigns each sample to taxonomic suborder. Not all samples were identified to this level, indicated by na. |
string | |
superfamily | Assigns each sample to taxonomic superfamily. Not all samples were identified to this level, indicated by na. |
string | |
family | Assigns each sample to taxonomic family. Not all samples were identified to this level, indicated by na. |
string | |
subfamily | Assigns each sample to taxonomic subfamily. Not all samples were identified to this level, indicated by na. |
string | |
genus | Assigns each sample to taxonomic genus. Not all samples were identified to this level, indicated by na. |
string | |
guild | Assigns each sample to functional feeding group. |
string | |
comment | Some samples are marked as immature |
string | |
dry_mass | Average weight of one individual arthropod |
double | milligram |
indiv_count | Number of individuals of that morphospecies collected at that plant at that site, at that event |
integer | dimensionless |
Tabular: Monthly brittlebush biomass measures 2007
Description: Denormalized table of monthly measurements of brittlebush dimensions collected from December 2006 to May 2007, site data included
Temporal Coverage: 2006-12-31 to 2007-05-31
Column | Description | Type | Units |
---|---|---|---|
site_id | Site codes, key is given in the worksheet Sites |
string | |
site_number | Assigned number |
integer | |
name | Location for plot (park, school, or nearest building) |
string | |
habitat_type | Which type of habitat: Urban, Desert or Remnant |
string |
Enumeration:
|
plant_id | Each plant per site was given a number from 1-60 |
integer | |
treatment_id | Color code for each treatment:R Cage, low water, O No cage, low water, B Cage, medium water, G No cage, medium water, Y Cage, high water, P No cage, high water |
string |
Enumeration:
|
plant_tag | Treatment code - combination of site, plant number and treatment |
string | |
height | Above ground measure of plant height |
integer | centimeter |
D1 | Diameter of plant crown from above |
integer | centimeter |
D2 | Diameter of plant crown, perpendicular to D1 |
integer | centimeter |
D3 | Diameter of plant crown, 45 degrees to D1 |
integer | centimeter |
D4 | Diameter of plant crown, perpendicular to D3 |
integer | centimeter |
plant_dry_mass | Estimated aboveground biomass after drying: Log(biomass)=1.01691xlog(Height x(D1+D2+D3+D4)/4)-2.94134 |
double | gram |
month | Name of month for collection |
string | |
field_personnel | The person measuring the plants EM = Erin Manton, CB = Christofer Bang, and MK = Matt King |
string |
Enumeration:
|
Tabular: Monthly brittlebush biomass measures 2008
Description: Denormalized table of monthly measurements of brittlebush dimensions collected from December 2007 to May 2008, site data included
Temporal Coverage: 2007-12-31 to 2008-05-31
Column | Description | Type | Units |
---|---|---|---|
site_id | Site codes, key is given in the worksheet Sites |
string | |
site_number | Assigned number |
integer | |
name | Location for plot (park, school, or nearest building) |
string | |
habitat_type | Which type of habitat: Urban, Desert or Remnant |
string |
Enumeration:
|
plant_id | Each plant per site was given a number from 1-60 |
integer | |
treatment_id | Color code for each treatment:R Cage, low water, O No cage, low water, B Cage, medium water, G No cage, medium water, Y Cage, high water, P No cage, high water |
string |
Enumeration:
|
plant_tag | Treatment code - combination of site, plant number and treatment |
string | |
height | Above ground measure of plant height |
integer | centimeter |
D1 | Diameter of plant crown from above |
integer | centimeter |
D2 | Diameter of plant crown, perpendicular to D1 |
integer | centimeter |
D3 | Diameter of plant crown, 45 degrees to D1 |
integer | centimeter |
D4 | Diameter of plant crown, perpendicular to D3 |
integer | centimeter |
plant_dry_mass | Estimated aboveground biomass after drying: Log(biomass)=1.01691xlog(Height x(D1+D2+D3+D4)/4)-2.94134 |
double | gram |
month | Name of month for collection |
string | |
field_personnel | The person measuring the plants EM = Erin Manton, CB = Christofer Bang, and MK = Matt King |
string |
Enumeration:
|