Christopher J. Anderson and B. Graeme Lockaby

Auburn University, School of Forestry and Wildlife Sciences,

Auburn, AL 36849

Changes in forested wetland composition, structure, and processes along a tidal gradient on the

Apalachicola River, FL, USA

June 4, 2012

9th INTECOL International Wetland Conference, Orlando, FL

Introduction • Methods • Results/Discussion • Summary

Tidal freshwater forested wetlands Upriver extent of tidal influence

Most prominent on larger rivers with gradual relief

Normally freshwater but prone to periodic saltwater intrusion

Wetland forests across a tidal gradient on the Apalachicola River

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Introduction • Methods • Results/Discussion • Summary

Environmental services related to forested riparian wetlands along the river Carbon/nutrient cycling

Water quality

Wildlife habitat

Forest products

Wetland forests across a tidal gradient on the Apalachicola River

Project goal Using the Apalachicola River, evaluate how

forested wetland conditions and processes change across a tidal gradient

Objectives Examine how tidal hydrology influences:

Forest structure and composition

Physio-chemical conditions

Foliar nutrient cycling

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Lower

Apalachicola

River study

sites.

Wetland forests across a tidal gradient on the Apalachicola River

Study design

•17 transects

•37 forest plots (500 m2)

•10 water level recorders

Introduction • Methods • Results/Discussion • Summary

Wetland measures across a tidal gradient Species structure and composition (2007-10):

Measured forest tree (>2.5 cm dbh) density, basal area/growth, and size class

Determined species importance values and community composition

Forest soils and woody debris (2009-10)

Soil nutrient conditions (% C, N, S, exch. P)

Electrical conductivity

Coarse woody debris

Examined N and P leaf translocation and flux by tidal and non-tidal trees(2008)

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Cluster analysis dendrogram for lower Apalachicola River forested wetlands. Matrix color

coding based on species IV range between 0 (Min) and 64 (Max).

Swamp tupelo-

Bald cypress

Cabbage palm-

Sweet bay

Ogechee tupelo-

Overcup oak

Water oak- Carolina

ash

Anderson and Lockaby. 2011. Wetlands 31:895-906.

Introduction • Methods • Results/Discussion • Summary

Community composition

Wetland forests across a tidal gradient on the Apalachicola River

Hummock

Hollow

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Importance values for Nyssa biflora and Taxodium distichum related to plot elevation

coefficient of variation in tidal stands along the lower Apalachicola River.

y = -0.0002x3 + 0.0254x2 - 1.3004x + 22.192

R2 = 0.3297

0.0

0.1

0.2

0.3

0.4

0.5

0.6

50 55 60 65 70

Plot elevation CV

Taxo

diu

m d

isti

ch

um

IV

1.0

y = -0.0307x + 2.1483

R2 = 0.6218

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

50 55 60 65 70

Plot elevation CV

Nyssa b

iflo

ra IV

1.0

Micro-topography and species composition

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Mean (±SE) density and tree size classes for tidal (n=7) and non-tidal (n=8) forest stands

along the lower Apalachicola River.

0

100

200

300

400

500

600

700

800

900

2.5 - 5.0 cm 5.0 - 10.0 cm 10.0 - 15.0 cm 15.0 - 20.0 cm > 20.0 cm

Tree DBH class

No

. s

tem

s h

a-1

Non-tidal

Tidal

Mean forest tree density:

Tidal: 1446 ±159 stems ha-1

Non-tidal: 962 ±962 stems ha-1

Anderson, Lockaby, and Click. In revision.

Tree stem density and size class

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Mean (±SE) basal area and annual increment growth of tidal (n=7) and non-tidal (n=8) forest

stands

-0.4

-0.2

0

0.2

0.4

0.6

0.8

2007-08 2008-09 2009-10

BA

I (m

2 h

a-1

yr-1

)

Tidal

Non-tidal

Mean forest basal area*

Tidal: 35.6 ±3.3 m2 ha-1

Non-tidal: 64.4 ±2.8 m2 ha-1

Anderson, Lockaby, and Click. In revision.

Basal area and increment growth

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Mean (±SE) surface soil (0-15 cm) measures for tidal (n=20) and non-tidal (n=17) forest plots along

the lower Apalachicola River. Letters denote significant differences (p<0.05) per nested ANOVA.

Electrical

conductivity

(mmhos cm-1)

0.0

1.0

2.0

3.0

4.0

Non-

tidal

Tidal

Carbon (%)

0.0

5.0

10.0

15.0

Non-

tidal

Tidal

Nitrogen (%)

0.0

0.2

0.4

0.6

0.8

1.0

Non-

tidal

Tidal

Sulfur (%)

0.0

0.1

0.2

0.3

0.4

Non-

tidal

Tidal

Mean surface soil measures

Exch.

Phosphorus

(ppm)

0.0

1.0

2.0

3.0

4.0

5.0

Non-

tidal

Tidal

Introduction • Methods • Results/Discussion • Summary

a a a a a b b b b b

Wetland forests across a tidal gradient on the Apalachicola River

Mean (±SE) coarse woody debris (CWD) for tidal (n=3) and non-tidal (n=5) forest stands along the

lower Apalachicola River. * denotes significant difference detected at p<0.05 per ANOVA.

0

1

2

3

4

5

6

<7.62 cm >7.62 cm

CWD size class

Mg

ha

-1Non-tidal

Tidal*

Anderson, Lockaby, and Click. In revision.

Coarse woody debris

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Percent tidal (n=19) and non-tidal (n=9) trees sampled with complete, intermediate, or

incomplete resorption proficiency of a) nitrogen and b) phosphorus (per Killingbeck 1996).

0

20

40

60

80

100

Complete Intermediate Incomplete

Pe

rce

nt

Non-tidal

Tidal

0

20

40

60

80

100

Complete Intermediate Incomplete

Pe

rce

nt

Non-tidal

Tidal

(<3 μg P

cm-2)

(3-8 μg P

cm-2)

(>8 μg P

cm-2)

(<50 μg N

cm-2)

(50-75 μg N

cm-2)

(>75 μg N

cm-2)

a) b)

Nutrient resorption proficiency

Anderson and Lockaby. 2011. Aquatic Botany 95:153-160.

Introduction • Methods • Results/Discussion • Summary

Wetland forests across a tidal gradient on the Apalachicola River

Estimated litterfall and nutrient flux for tidal (n=5) and non-tidal (n=3) forest stands along the

lower Apalachicola River.

1 4399 35.8 1.4

2 3997 31.9 1.4

15 3672 31.2 1.2

7pt 4513 36.8 1.4

WS2 2472 21.0 1.0

Avg. 3811 31.3 1.3

3 8107 100.4 5.3

5 5661 71.6 3.9

7 6180 77.5 4.0

Avg. 6649 83.2 4.4

N (kg ha-1

) P (kg ha-1

)

Litterfall

(kg ha-1

)Plot

Introduction • Methods • Results/Discussion • Summary

Tidal

Non-tidal

Anderson and Lockaby. 2011. Aquatic Botany 95:153-160.

Litterfall and nutrient flux

Summary of findings: Forest tree species and community composition

provided clear indications of tidal influence

Microtopography within tidal sites appears to be important for community composition

Tidal hydrology and periodic saltwater intrusion resulted in consistent differences in soil C, N, S, exch. P, electrical conductivity, and other soil measures

Tidal wetlands appeared to be P-limited based on nutrient resorption efficiencies and N:P and C:P ratios

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Summary of findings (continued): Tidal wetlands appeared to be P-limited based

on leaf nutrient resorption measures and foliage/litterfall N:P and C:P ratios.

The nutrient pool associated with tidal forests is significantly lower than non-tidal forests.

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Acknowledgements AU Center for Forest Sustainability, McIntire-Stennis Grant

Program

Apalachicola National Estuarine Reserve, Florida Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission

A. Cerro, F. Barksdale, J. Clewley, N. Click, J. Dow, R. Governo, R. Jolly, T. Kesler, L.Levi, H. Light, J. Mitchell, J. Morse, W. Morse, J. Timpone, J. Trusty, J. Wanat

Wetland forests across a tidal gradient on the Apalachicola River

Introduction • Methods • Results/Discussion • Summary

Introduction • Methods • Results/Discussion

Environmental services related to forested riparian wetlands Carbon cycling

Wildlife habitat

Water quality

Wetland forests across a tidal gradient on the Apalachicola River