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Key connections in Amazonian Key connections in Amazonian stream corridors: Using stream corridors: Using 15 15 N to N to trace N transformations and trace N transformations and transport transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester, Gessner, Haupert, Thomas UPLAND SMALL STREAM RIPARIAN LARGE RIVERS SLOPE

Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

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Page 1: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

Key connections in Amazonian Key connections in Amazonian stream corridors: Using stream corridors: Using 1515N to N to trace N transformations and trace N transformations and transport transport

ND-03: Deegan, Neill, Victoria, Krusche, Ballester, Gessner, Haupert, Thomas

UPLAND

SMALLSTREAM

RIPARIAN

LARGE RIVERS

SLOPE

Page 2: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

FOREST TO PASTURE FOREST TO PASTURE CONVERSIONCONVERSION

• dissolved nutrients & nutrient ratios,

• stream conditions (e.g., oxygen) and

• biota (e.g., increased algae, loss of invertebrates in pastures)

N & P processing affected by changes in:

Page 3: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

KEY QUESTIONSKEY QUESTIONS

• How and at what rates is nitrogen How and at what rates is nitrogen transformed in tropical forest streams?transformed in tropical forest streams?

• How does conversion to pasture alter N How does conversion to pasture alter N cycle?cycle?

• How far and in what form is nitrogen How far and in what form is nitrogen transported? transported?

Page 4: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

FATE AND TRANSFORMATION OF NITROGENFATE AND TRANSFORMATION OF NITROGEN

Page 5: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

15N NH4

+ UPTAKE

-10 0 30 40 50 60 80 800

Downstream Distance (m)> > >

Measure 15N of 15NH4+,

15NO3- and organic matter (including biota)

1515N Addition SchematicN Addition Schematic

2

4

3 5 68

Dripper

1

15N

STREAM

FLOW

79

Add 15(NH4)2SO4 for 21 days to raise the 15N of stream NH4

+

Conversion to other components

Page 6: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

15N

of N

H4+

DISTANCE (M)

UPTAKE LENGTH - NHUPTAKE LENGTH - NH44++

0

100

200

300

-100 100 300 500 700

Day 1Day 21

3000m

1000m

Temperate Stream ~50m

Page 7: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

0

100

200

300

d1

5N

-20 280 580 880

m_down_plot

NO3NH4

Bivariate Line ChartSplit By: TypeInclusion criteria: A Nh4/no3/day from Br Forest 15N.stv

0

50

100

150

d1

5N

-20 280 580 880

m_down_plot

NO3NH4

Bivariate Line ChartSplit By: TypeInclusion criteria: A Nh4/no3/day from Br Forest 15N.stv

Day 1 Day 21

DISTANCE (M)

0

100

200

300

d15N

-20 280 580 880

m_down_plot

NO3NH4

Bivariate Line ChartSplit By: TypeInclusion criteria: A Nh4/no3/day from Br Forest 15N.stvNITRIFICATION RATENITRIFICATION RATE

15N

RATE: ~5 X 10-6 m-1 or 2 x 10-5 ug/m2/min

~10% of NH4 loss converted to NO3

Page 8: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

Temperate TropicalWalker Branch, TN Nova Vida, RO

NH4+ uptake length (m) 30 2000

NO3- uptake length (m) 500 infinite

Nitrification rate (1/m) 10-3 10-6

FOREST STREAM FOREST STREAM COMPARISIONCOMPARISION

Page 9: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

% of 15N added Temperate TropicalWalker Branch Nova Vida

Retained 48 2

Total export 31 69

FOREST STREAM N MASS FOREST STREAM N MASS BALANCEBALANCE

NO3 23 8

NH4 4 60

Particulate 4 1

Page 10: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

Effect of conversion to Effect of conversion to pasture?pasture?

0

500

1000

1500

-200 0 200 400 600

NO3

NH4

Small pasture stream

0

200

400

600

800

-100 100 300 500 700

NO3

NH4

Larger pasture stream

15N

Ammonium uptake length is shorter

(~500m)

Nitrification rate is near zero

For the rest of the story – see the poster Haupert 37.5

Page 11: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

NHNH44++ uptake length is 10 to 100 times uptake length is 10 to 100 times

longer than in temperate streamslonger than in temperate streams

Peterson et al. 2001

TROPICAL FOREST STREAM

At 40 L s-1

TropicalForest: 2000mPasture: 500m

TemperateForest: 50 m

PASTURESTREAM

Page 12: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

New Knowledge New Knowledge

• Not like temperate forest streams– Little transformation of DIN

• Low rates of nitrification• Little storage; Low rate of N release from

stream bottom

– Little retention of N occurs• Long downstream transport > 1000’s m • Primarily as DIN• Function as conduits that transport N from

upper reaches of watersheds to larger rivers.

Page 13: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

New KnowledgeNew Knowledge

• Pasture formation radically alters N transformation and transport

– Nitrification is near zero in pasture streams

– NH4+ uptake length is shorter (500m) than

in tropical forest (2000m)

….. but still 10X longer than temperate forest

(50m)

Page 14: Key connections in Amazonian stream corridors: Using 15 N to trace N transformations and transport ND-03: Deegan, Neill, Victoria, Krusche, Ballester,

SYNTHESIS & SCALINGSYNTHESIS & SCALINGSynthesis of stream N, P Synthesis of stream N, P and C processes across and C processes across different soil types and different soil types and regionsregions

Develop a model to Develop a model to integrate land use mosaic integrate land use mosaic with stream chemistry, with stream chemistry, stream size, riparian area stream size, riparian area and hydrology to predict and hydrology to predict the export of materials to the export of materials to larger rivers.larger rivers.