Hydrogeomorphic Assessment of Beanblossom Bottoms Nature Preserve Sycamore Land Trust

Hydrogeomorphic Assessment of Beanblossom Bottoms Nature Preserve Sycamore Land Trust Thuy Thi Hong An SPEA E 440 – Wetlands Fall 2011 1.. Introduction We were asked by the Sycamore

Hydrogeomorphic Assessment

of Beanblossom Bottoms Nature Preserve

Sycamore Land Trust

Thuy Thi Hong An SPEA E 440 – Wetlands

Fall 2011

1 Introduction

2 Methods

2.1 Site description

2.2 HGM assessment

3 Results and discussion

4 Conclusion

5 Literature cited

6 Figures and Tables

1 Introduction

We were asked by the Sycamore Land Trust, a local conservation organization, to evaluate the wetland ecological functions of the Beanblossom Bottoms Nature Preserve This wetland had been converted from an agriculture site to gain wetland mitigation credits The Sycamore Land Trust is interested in selling these mitigation credits to INDOT to compensate for the loss of wetlands caused by the construction of I – 69 Hydrogeomorphic (HGM) approach was applied to calculate the mitigation ratio by evaluating wetland functions of the mitigation site compared to the reference site

2 Methods

2.1 Site description

The Beanblossom Bottoms Nature Preserve is a high quality hardwood wetland owned

by the Sycamore Land Trust The latitude and longitude of this site are North 39 16.612 and West 86 34.713 respectively (Cyberindiana 2011) The Beanblossom Bottoms Nature Preserve used to be a farm land According to the Soil survey of Monroe County, Indiana (1981), the soils

in the reference site are Zipp silty clay loam and Bonnie silt loam while the soil in the restored site is Stendal silt loam (Figure 1) The mitigation site is marked by a star in Figure 2 The reference site is the nearby forested wetland which has minimum disturbance

2.2 HGM approach

The HGM classification system is based on three main criteria including landscape position, water source, and hydrodynamics (Craft 2011) This approach was applied to evaluate the functional indices of the mitigation wetland in comparing with the reference wetland of the same type Wetlands deliver a wide range of functions associated with four general categories:

Hydrology, biogeochemistry, plant habitat, and animal habitat (Hauer 1998) Therefore, it is impossible to assess all functions In this project, we evaluated only one function for each category as following

Table 1: Ecological functions evaluated in HGM method

1 Hydrology Long-term surface water storage

2 Biogeochemistry Nutrient cycling

3 Plant habitat Maintain characteristic plant communities

4 Animal habitat Maintain spatial structure of habitat

Due to time limitation, only one sampling plot was established at the mitigation site and

a similar sampling plot was established at the reference site Direct measurements were done on-site while indirect measurements were estimated off-site The detail information and results are summarized in Table 3 The reference site was given a score of one for each index of variable The scores assigned for variables of the mitigation site were based on their likeness to the reference site The total function index was the average scores of the four functional categories The ratio of total function index of the reference site to the mitigation site is called the HGM mitigation ratio Because forested wetlands have a failure rate of 71%, an adjusted HGM mitigation ratio is necessary (Robb 2002) The below equation is used to calculate the adjusted HGM mitigation ratio

Adjusted HGM mitigation ratio = HGM mitigation ratioSuccess rate

In the case of forested wetlands, the success rate is 29% or 0.29 (Robb 2002)

3 Results and discussion

The overall results are shown in Table 2 Comparing to the reference standard, the mitigation site had the long-term surface water storage score of 0.75 Therefore, it can provide about 75% of ecological functions related to long-term surface water storage delivered by the reference site This result is logical since the mitigation site is adjacent to the reference site accounting for their similar macrotopography The nutrient cycling score of the restored site was only 0.1 proving that the restored site was not good at providing biogeochemical functions The scores for maintaining characteristic plant community and spatial structure of habitat were 0.51 and 0.52 respectively In other words, the mitigation wetland can deliver a half level of functions as plant and animal habitats compared to those provided by the reference wetland

Table 2: Index of variables for reference site and mitigation site

at Beanblossom Bottoms Nature Preserve

Reference site Mitigation site

Mitigation ratio 1 : 0.47 = 2.13 : 1 Failure adjusted mitigation ratio (2.13/0.29) : 1 = 7.34 : 1

The total function index based on the above four wetland ecological functions was 0.47

It means that the mitigation site can perform about 47% of ecological functions provided by the reference site The mitigation ratio was 2.13 indicating that we need 2.13 hectares of mitigation

wetlands to deliver the same level of functions provided by 1 hectare of reference wetlands Due to a failure rate of 71% for forested wetlands, 7.34 hectares of constructed forest wetland was recommended to compensate for the loss of 1 hectare of natural forested wetland

4 Conclusion

Sycamore Land Trust should proceed with creating the mitigation bank to sell mitigation credits for INDOT The recommended scale is 2.13 : 1 which means that 2.13 hectares of the mitigation wetland is needed to replace 1 hectare of the natural wetland destroyed However, a mitigation ratio of 7.34 : 1 could be applied to ensure higher successful mitigation

5 Literature cited

1 Craft, Christopher B (2011) Wetlands: Biology and Regulation Classpak Publishing Indiana University

2 Hauer, F R and R D Smith (1998) "The hydrogeomorphic approach to functional assessment of riparian wetlands: evaluating impacts and mitigation on river floodplains in the

U.S.A." Freshwater Biology 40(3): 517-530

3 Robb, J T (2002) "Assessing wetland compensatory mitigation sites to aid in establishing mitigation ratios." Wetlands 22(2): 435-440

4 Soil survey of Monroe County, Indiana 1981 Soil Conservation Service, U S Department of Agriculture

5 U.S Department of Agriculture Natural Resources Conservation Service

6 Syscamore Land Trust

7 Cyberindiana

Last accessed December 6th, 2011

6 Figures and Tables

Figure 1: Soil surveys at Beanblossom Bottoms Nature Preserve Data from US Department of Agriculture Natural Resources Conservation Service November, 2011

Figure 2: Sycamore Land Trust property boundaries for the Beanblossom Bottoms Nature Preserve, Monroe County, IN

(After Sycamore Land Trust Website, accessed on December 5th, 2011)

Table 3: Summary of values and calculation for wetland functions using hydrogeomorphic index

at Beanblossom Bottoms Nature Preserve, Sycomore Land Trust (Data collected on December 2 nd , 2011)

LONG-TERM SURFACE WATER STORAGE

Indicators of

surface water

present

Visual observation of water mark, buttress, moss

~30.5 cm flooding observed from watermarks, buttressing and moss on

~ 15.25 cm flooding observed from watermarks

relief Estimated by viewing aerial photograph (Google earth) Uniformly flat Minor elevation changes (dead trees) 1.0 Uniformly flat 1.0

Index of Function = (V Surfacewater + V Macro )/2 0.75

NUTRIENT CYCLING

productivity Determined by measuring thickness of leaf litter layer

6 cm

7 cm

6 cm = 6.0 cm average

5 cm

6 cm

1.0

9 cm

6 cm

6 cm = 7.8 cm average

10 cm (130% calculated)

8 cm

0.5

of detritus

Determined by measuring the thickness of A horizontal layer

Very thin organic layer if present

< 1.0 cm of darker organic matter at

No observable organic A horizon

Larger chunks of organic matter (leaf litter) than reference site

0.1

Index of Function If V Aerial NPP > V Turnover then index is V Turnover otherwise use V Aerial NPP 0.1

MAINTAIN CHARACTERISTIC PLANT COMMUNITY

Species

composition for

tree (T), sapling

(SAP), shrub (S),

and ground cover

(GC) strata

Determined 3 dominant species for each strata

Plot size:

Trees >5cm DBH in 10 m radius

Saplings/shrubs in 5 m radius

Herbaceous in 2 m radius

T: Fraxinus pennsylvanica, Quercus

bicolor, Quercus palustris

SAP: Acer rubrum, Fraxinus

pennsylvannica

S: None

GC: Boehmeria cylindrical, Misc

Sedge, Misc Poacea spp

1.0

T: Fraxinus pennsylvanica,

Platanus occidentalis, Acer rubrum [1]

SAP: Acer rubrum, Platanus

occidentalis, Quercus alba

[1]

S: None

GC: Boehmeria cylindrical,

Misc Sedge, Misc Poacea spp., Lysimachia

nummularia [3]

0.25

Seedlings/saplings

and/or clonal

shoots

Estimated ratio of seedlings

VCANOPY Canopy cover Visual estimation of 10 m radius on site T: 90% 1.0 T: 80% 1

Measured DBH in a 10 m radius plot for all tree species > 5 cm DBH using a standard DBH tape

Acer rubrum- 28 33 15 13 19 25 27 28

30 31 30 16 24

Fraxinus pennsylvanica- 83 74 117 90

80 100 25 75 116 84 42 27 80 65 85

59 16 75 69 70 83 84 75 65

Quercus spp- 134 96 78 80 90 65 79

82 77 68 83

Ulmus Americana- 29 30 35 42 40 30

27 39 33 Total = 3295

1.0

Acer rubrum- 16 22 20 18

14 16 18 30 16 20

Fraxinus pennsylvanica- 20

13 10 15 15 20 10 10 18

Platanus occidentalis- 28 13

28 18 27 25 28 32 47 40 34

20 35 32 15 20 22 20 20 21

29

Populus deltoides- 99 Quercus palustris- 35 32 30

15 Total = 1086 (33%)

0.5

Index of Function = [(V Composition + V Regeneration + V Canopry Cover ) + (V Tree Density + V Basal Area)/2] /4 0.51

MAINTAIN SPATIAL STRUCTURE OF HABITAT

Density of

standing dead

trees

Counted standing dead

Number and

attributes of

vertical strata of

vegetation

Estimated number of strata and their percent coverage

Trees: 90%

Saplings: 80%

Shrubs: 10%

Ground cover: 30%

1.0

80%

0%

0%

100%

0.5

Index of Function = (V Snags + V Mature Trees + V Strata + V Patch + V Gaps ) /5 0.52

Mitigation ratio 2.13 : 1 Failure adjusted mitigation ratio 7.34 : 1