Riparian Carbon and Nitrogen Cycling: Influences of Spatial Heterogeneity and Hydrologic Vectors
Author(s):
- Tamara Harms
- Nancy Grimm, School of Life Sciences, Arizona State University
Abstract:
Terrestrial and aquatic ecosystem ecologists study the same phenomena (e.g., nutrient cycling, energy flow, succession) but they do so within separate conceptual frameworks. Terrestrial frameworks address state factors of climate, organisms, parent material, topography, and time to understand ecosystem processes within a location, but less often consider how ecosystems are connected. Aquatic ecologists, especially those studying flowing waters, emphasize the role of water as a means of propagating processes and materials through space and time. Both terrestrial and aquatic ecosystems contain hydrologic vectors as well as soils or sediments that record the influences of state factors. This dissertation is an investigation of carbon and nitrogen cycling in the stream-riparian corridor of the San Pedro River, a large desert river, and tests the relative effects of soil characteristics and hydrologic vectors. Riparian zones are well suited to such investigations because they are spatially heterogeneous and subject to material and water inputs from multiple hydrologic vectors. Spatially explicit methods showed that flood vectors homogenized soil characteristics and denitrification along a stream reach with frequent overbank floods, whereas soils of a riparian site that was infrequently inundated by floods were heterogeneous. Legacies of previous floods appeared to determine the spatial locations of denitrification at the latter site. At a plot scale, manipulation of precipitation and flood vectors across a gradient of soil types showed that water functioned as an essential resource during the dry season, resulting in increased emissions of trace gases following simulation of floods. Following inundation of riparian soils by several monsoon floods, however, further addition of water appeared to suppress biogeochemical activity by decreasing oxygen availability. Thus desert riparian ecosystems appear to shift seasonally along a terrestrial-aquatic continuum, functioning similarly to terrestrial ecosystems during dry seasons, but like wetlands following inundation by floods. Finally, analyses encompassing several years of observations revealed strong correlations between regimes of hydrology and resource availability. Overall, this study demonstrates that the hydrologic regime drives spatial and temporal patterns in biogeochemical processes, but that soil characteristics may modify the duration and magnitude of biological responses to hydrologic vectors in desert riparian ecosystems.
Keywords:
Temporal Coverage:
2001-01-01 to 2007-12-31Geographic Coverage:
Geographic Description: The Phoenix Metropolitan area is located at the Northern edge of the Sonoran DesertBounding Coordinates:
Longitude:-110.1860 to -110.1378
Latitude:31.6896 to 31.5553
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 (5) :
Tabular: 335_gas_1.csv
Description: soil gas concentrations
Column | Description | Type | Units |
---|---|---|---|
ID | Automatically generated sequential id
number |
integer | |
plot | Plot within a site |
string | |
season | Season with regards to precipitation (dry,
monsoon) |
string | |
site | Site ID as used in sites table |
string | |
trt | treatment (flood, precipitaiton) |
string | |
time | time in hours |
float | nominalHour |
airT | air temperature |
float | celsius |
soilT | soil temperature |
float | celsius |
Eh | redox potential |
float | millivolt |
soilmoist | soil moisture |
float | dimensionless |
N2O | N2O flux |
float | microgramPerMeterSquaredPerHour |
CO2 | CO2 flux |
float | microgramPerMeterSquaredPerHour |
CH4 | CH4 flux |
float | microgramPerMeterSquaredPerHour |
Tabular: 335_grid_soil_1.csv
Description: soil texture and chemical concentrations in grid
experiment
Column | Description | Type | Units |
---|---|---|---|
ID | Automaticall generated sequential ID
number |
integer | |
X | X coordinate of grid point |
float | number |
Y | Y coordinate of grid point |
float | number |
SITE | site ID as used in sites table |
string | |
SEASON | Season of sampling (dry, monsoon) |
string | |
PCT_MOIST | percent moisture |
float | dimensionless |
PCT_AFDM | percent ash free dry mass |
float | dimensionless |
DENIT | potential rate of denitrification |
float | milligramPerMeterSquaredPerHour |
PCT_SAND | percent sand |
float | dimensionless |
PCT_SILT | percent silt |
float | dimensionless |
PCT_CLAY | percent clay |
float | dimensionless |
PCT_SILTCL | percent sitl plus clay |
float | dimensionless |
NO3 | resin available nitrate |
float | microgram |
NH4 | resin available ammonium |
float | microgram |
Tabular: 335_sites_1.csv
Description: site descriptions
Column | Description | Type | Units |
---|---|---|---|
site_code | site ID |
string | |
E | East in UTM |
float | meter |
N | North in UTM |
float | meter |
site_name | site name |
string | |
site_description | ecological description of site |
string |
Tabular: 335_soil_solute_timeseries_1.csv
Description: soil solute chemical concentrations over time
Column | Description | Type | Units |
---|---|---|---|
ID | Automatically generated sequential ID
number |
integer | |
month | month |
float | nominalMonth |
day | day of the month |
float | nominalDay |
year | year |
float | nominalYear |
s_pctOM | surface soil percent organic matter |
float | dimensionless |
s_moist | surface soil percent moisture |
float | dimensionless |
s_NO3 | surface soil extractable NO3 in mg per kg dry
soil |
float | dimensionless |
s_NH4 | surface soil extractable NH4 in mg per kg dry
soil |
float | dimensionless |
s_TN | surface soil extractable total N in mg per kg dry
soil |
float | dimensionless |
s_extOC | surface soil extractable organic Carbon in mg per kg dry
soil |
float | dimensionless |
s_Nmin | surface soil net N mineralization |
float | microgramPerKilogramPerDay |
s_nitrif | surface soil nitrifaction |
float | microgramPerKilogramPerDay |
s_MBC | surface soil microbial biomas in milligrams C per kilograms
dry soil |
float | dimensionless |
s_MBN | surface soil microbial biomas in milligrams N per kilograms
dry soil |
float | dimensionless |
s_denit | surface soil potential denitrifaction |
float | microgramPerKilogramPerDay |
r_pctOM | region of seasonal saturation soil percent organic
matter |
float | dimensionless |
r_moist | region of seasonal saturation soil percent
moisture |
float | dimensionless |
r_NO3 | region of seasonal saturation soil extractable NO3 in mg
per kg dry soil |
float | dimensionless |
r_NH4 | region of seasonal saturation soil extractable NH4 in mg
per kg dry soil |
float | dimensionless |
r_TN | region of seasonal saturation soil extractable total N in
mg per kg dry soil |
float | dimensionless |
r_extOC | region of seasonal saturation soil extractable organic
Carbon in mg per kg dry soil |
float | dimensionless |
r_Nmin | region of seasonal saturation soil net N
mineralization |
float | microgramPerKilogramPerDay |
r_nitrif | region of seasonal saturation soil
nitrifaction |
float | microgramPerKilogramPerDay |
r_MBC | region of seasonal saturation soil microbial biomas in
milligrams C per kilograms dry soil |
float | dimensionless |
ln_MBN | region of seasonal saturation soil microbial biomas in
milligrams N per kilograms dry soil |
float | dimensionless |
r_denit | region of seasonal saturation soil potential
denitrifaction |
float | microgramPerKilogramPerDay |
Tabular: 335_water_solute_timeseries_1.csv
Description: water solute chemical concentrations over time
Column | Description | Type | Units |
---|---|---|---|
ID | Automatically generated sequential ID
number |
integer | |
month | Month of the year |
float | nominalMonth |
day | Day of the month |
float | nominalDay |
year | Year |
float | nominalYear |
s_T | surface stream temperature |
float | celsius |
s_pctsat | surface stream dissolved oxygen, percent
saturation |
float | dimensionless |
s_DO | surface stream dissolved oxygen |
float | milligramsPerLiter |
s_spcond | surface stream specific conductivity |
float | microSiemensPerCentimeter |
s_pH | surface stream pH |
float | dimensionless |
s_NO3 | surface stream NO3 |
float | milligramsPerLiter |
s_NH4 | surface stream NH4 |
float | milligramsPerLiter |
s_TN | surface stream total N |
float | milligramsPerLiter |
s_DON | surface stream organic N |
float | milligramsPerLiter |
s_Cl | surface stream Chloride |
float | milligramsPerLiter |
s_SRP | surface stream soluble reactive
phosphate |
float | microgramsPerLiter |
s_DOC | surface stream organic carbon |
float | milligramsPerLiter |
s_NO3:NH4 | surface stream molar ratio of NO3 to
NH4 |
float | dimensionless |
s_DOC:DON | surface stream molar ratio of organic carbon to organic
nitrogen |
float | dimensionless |
s_NO3:SRP | surface stream molar ratio of NO3 to soluble reactive
phosphate |
float | dimensionless |
s_fracDON | surface stream organic N fraction |
float | dimensionless |
w_T | shallow riparian groundwater
temperature |
float | celsius |
w_pctsat | shallow riparian groundwater dissolved oxygen, percent
saturation |
float | dimensionless |
w_DO | shallow riparian groundwater dissolved
oxygen |
float | milligramsPerLiter |
w_spcond | shallow riparian groundwater specific
conductivity |
float | microSiemensPerCentimeter |
w_pH | shallow riparian groundwater pH |
float | dimensionless |
w_NO3 | shallow riparian groundwater NO3 |
float | milligramsPerLiter |
w_NH4 | shallow riparian groundwater NH4 |
float | milligramsPerLiter |
w_TN | shallow riparian groundwater total N |
float | milligramsPerLiter |
w_DON | shallow riparian groundwater organic
N |
float | milligramsPerLiter |
w_Cl | shallow riparian groundwater Chloride |
float | milligramsPerLiter |
w_SRP | shallow riparian groundwater soluble reactive
phosphate |
float | microgramsPerLiter |
w_DOC | shallow riparian groundwater organic
carbon |
float | milligramsPerLiter |
w_NO3:NH4 | shallow riparian groundwater molar ratio of NO3 to
NH4 |
float | dimensionless |
w_DOC:DON | shallow riparian groundwater molar ratio of organic carbon
to organic nitrogen |
float | dimensionless |
w_NO3:SRP | shallow riparian groundwater molar ratio of NO3 to soluble
reactive phosphate |
float | dimensionless |
w_fracDON | shallow riparian groundwater organic N
fraction |
float | dimensionless |