# Presentation: 503261

## VERMONT WETLANDS BIOASSESSMENT 

## Seasonal Pools and Northern White Cedar Swamps

- Chemical, Physical, and Biological Characteristics
- Evaluate sampling and assessment methods
- Classification of reference condition
- Selection of pools and swamps along a disturbance gradient
- Testing of metrics

## Disturbance Ratings

- Reference pools = no obvious disturbance in 150m forested buffer area
- Disturbance types: logging, hydrologic alteration, water quality alteration, agriculture, development (residential and commercial/industrial)
- Each type ranked 0 to 3, none, minimal, moderate, and high
- Each site ranked for current condition and landscape quality

## Current Condition

- Current condition of community (pool or swamp):
-         1 = no signs of anthropogenic alteration,           	      no exotics, etc
-          2= moderate, some signs of ....
-          3= poor, obvious signs of .....

## Landscape Quality

- 1= surrounded by 1000+ acres of intact matrix of natural communities
- 2= surrounded by forest or undisturbed communities, but some development or logging nearby
- 3= surrounded by fragmented forest, agricultural land and rural development
- 4= surrounding area intensely developed

## Seasonal Pool

- No permanent inlets or outlets
- Standing water for at least two months of the year in the spring
- Dries out for some portion of the year
- Also known as: vernal pools, autumnal pools, ephemeral pools, temporary pools
- PUBC, palustrine unconsolidated bottom, seasonally flooded or ponded

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## Physical Characteristics

- Latitude/longitude
- Maximum pool area
- Maximum water depth
- Substrate composition, % leaf litter
- 150m buffer reconnaissance
- Air and water temperature
- % canopy
- Watershed Area, Bedrock and Surficial Geology

## Water Sampling

- Samples for chemical analysis
- Field pH
- Color
- Alkalinity, Conductivity
- Anions, cations, Aluminum
- Lab pH

## Biological sampling

- Aquatic macroinvertebrates
- Algae
- Amphibians
- Vegetation

## Aquatic Macroinvertebrates

- Funnel traps: swimmers
- D-net scoops: benthic invertebrates
- Qualitative: D-net sweeps

## Amphibians

- Adults: species, presence/absence
- Egg masses: species, counts
- Spermatophores: counts
- Larvae: species, counts

## Trap Deployment in a Vernal Pool – entry hole submersed with air space at top to protect trapped amphibians

## Aquatic macroinvertebrate percent taxonomic richness by order. The percentages are based on the comprehensive project taxonomic list from all pools and all sampling methods. 

- Aquatic macroinvertebrate percent taxonomic richness by order. The percentages are based on the comprehensive project taxonomic list from all pools and all sampling methods.

**Notes:**
Aquatic macroinvertebrate composition
Of all the taxa collected, two orders represented the majority of all taxa found in this study: Diptera (35% of all taxa richness) and Coleoptera (23% of all taxa richness). See Figure 2. All other orders represented no more than 7% of total richness.  The "Other" category on Figure 1 represents the following Orders:  Hirudinea, Lepidoptera, Ephemeroptera, Tricladida, Megaloptera, Anostraca, Isopoda, Neorhabdocoela, Conchostraca.  Each of these Orders had no more than 5 taxa represented in seasonal pools.

## Results

- Traps represented 68% of all taxa collected
- Scoop method is very disruptive and inconsistent across space and time
- Scoops added approximately 21% to taxa richness
- Qualitative search added 11%

## Results

- TWINSPAN and DCA identified a subgroup of pools = 5 permanent pools
- Seventeen candidate metrics failed to show a significant difference between least disturbed (n=9) and more disturbed pools (n=14)
- TWINSPAN identified two beetle assemblages

## DCA joint plot of 28 pools with pools coded by their TWINSPAN Subgroups and important environmental variables shown as vectors. The four TWINSPAN Subgroups are also enclosed within freehand polygons to further show their separation. Based on presence/absence of all macroinvertebrate and plant taxa.

**Notes:**
The TWINSPAN Subgroup 1 and 2 pools separate from each other, with Subgroup 1 in the upper left and Subgroup 2 in the lower left of the DCA ordination. Similarly, Subgroups 1 and 2 are graphed on the left side of the ordination and separate from Subgroups 3 and 4, which are on the right side of the ordination. TWINSPAN Subgroups 3 is in the upper central portion of the ordination and Subgroup 4 is graphed in the lower right. Although the four TWINSPAN Subgroups can all be separated on this DCA ordination, it also clearly shows that the 28 pools form a continuum of variation, as is expected in nature. 

An important result of these TWINSPAN and DCA analyses was the identification of the Subgroup 1 pools, all of which were considered to be permanent pools based on field observations. Although the Carlton Hill pool did not fall out with the Subgroup 1 pools, it is also a permanent pool. Based on the field observations and these analyses, these five permanent pools were eliminated from further analyses of the subject seasonal pools. 

Percent canopy cover has a strong positive correlation with Axis 1 (r2=.630), with those pools that have relatively closed canopies on the right side of the ordination. The pools' perimeters are negatively correlated with Axis 1 (r2=.457), as is the percent of the maximum pool area covered by herbaceous vegetation (r2=.317). The inverse relationship between pool canopy cover and perimeter reflects the fact that for small pools the canopy of the adjacent upland forest closes over the pool, whereas for large pools, the adjacent upland trees only cover the fringe of the pool. 

Axis 2 of the DCA joint plot has positive correlations with depth of organic soil (r2=.217) and pool water color (r2=.272), and negative correlations with landscape quality rank (r2=.346) and sulfate concentration (r2=.230) 

In general, the disturbed pools in fragmented landscapes are graphed in the bottom half of the ordination, although several pools with high (Boyer) to moderate (Hampshire Hill and Thistle Hill) levels of disturbance are graphed in the top half of the ordination. It is clear that disturbed and reference pools cannot be separated consistently by this analysis. 

## Marsh Beetle pools

*Cyphon *sp. Indicator species
- Smaller perimeter and watershed
- Greater canopy cover
- Tending towards moderate to mildly acidic

## Diving Beetle Ponds

*Acilius sylvanus* indicator species
*Dytiscus fasciventris* and *Laccophilus maculosus*, predacious diving beetles
- Larger and less acidic
- Corresponding less canopy cover, more alkalinity

## Pool type vs disturbance rating

- 7 out of 9 of the “least disturbed” sites fell within the Marsh Beetle pools
- More disturbed sites were evenly divided between the two groups
- There was much overlap in metric value between the two groups

## Variability

- Seasonal
- Annual
- Replicate samples
- Methods
- Chemical and physical

## Example of seasonal variability on the occurrence and relative abundance of macroinvertebrate taxa

- Example of **seasonal variability** on the occurrence and relative abundance of macroinvertebrate taxa

**Notes:**
Demonstrates the large  variability in taxa occurrence and relative abundance between sampling events seperated by 4-6 weeks. Only 6 of 39 taxa (15%) common to both samples.

## Replicate qualitative samples demonstrating sampling variability on taxonomic occurrence and relative abundance. 

- Replicate qualitative samples demonstrating **sampling variability** on taxonomic occurrence and relative abundance.

**Notes:**
Taxa occurrence between replicate qualitative samples. Of 20 total taxa, only eight (40%) were common to both replicates. Definite differences in dominant taxa.

## Example of annual variability on the occurrence and relative abundance of taxa.

- Example of **annual variability** on the occurrence and relative abundance of taxa.

**Notes:**
This slide demonstrates the differences in taxonomic composition from year to year during similar season. Shows scoop samples collected in April of  1999 and 2000. Only five of 20 taxa (25%) were common to both sampling events. Dominant taxa  (>4%) were different between years. 

## Amphibians

- Wood frog (*Rana sylvatica)*
* *Spotted salamander (*Ambystoma maculatum)*
- 27 of 28 sites (96.4%) reference and disturbed sites, including permanent pools
- Jefferson salamander (*Ambystoma jeffersonian)* least common (7 of 28 sites)

## Vermont Wetlands Bioassessment Project

**Vermont Wetlands Bioassessment Project**
**Part 2**
**Northern White Cedar Swamps**

## Project Goal: to identify specific attributes that are indicators of ecological integrity in northern white cedar swamps

_**Methods**_:
- Based on 1996-1998 EPA funded statewide inventory of northern white cedar swamps (70 swamps) and four additional swamps visited for this study
- Data collected for 74 swamps: 20x20 meter vegetation plots and environmental variables; breeding bird surveys at six swamps
- Classification of swamps based on multivariate analyses
- All study swamps (38) ranked based on level and type of disturbance

## Analysis and Results:

- Two-Way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA) to identify types within the full set of swamps (74)

- Northern White Cedar Sloping Seepage Forest

- Red Maple-Northern White Cedar Swamp

- Boreal Acidic Northern White Cedar Swamp

- Northern White Cedar Swamp - Typical

## 2. TWINSPAN and DCA of 38 “Typical” northern white cedar swamps indicates that no further separation of types is warranted. Therefore this is the set of swamps used for further bioassessment study.

##  3. Environmental variables and disturbance ranking for 38 study swamps

## 4. Testing the difference in the median values between reference (total disturbance rank 0-3) and disturbed (4-9) swamps.

- Significant difference was found between the two groups for the following metrics, using Mann-Whitley and P<.001: disturbance rank, current condition, landscape quality, minimum buffer width, and percent of wetland with >50 meter buffer. This is expected as these measures are all based on the level of disturbance in and around the swamps.
- No significant differences in median values for these metrics, using Mann-Whitley or T-test: pH, conductivity, depth of organic soil, size, presence of old growth, presence of exotics, total richness, bryophyte richness, vascular plant richness, or percent cover by strata.

## 5. Plant species composition was compared between reference (0-3 total disturbance rank) and disturbed (4-9) swamps, but no distinguishing species are consistently found in reference or disturbed swamps.

- 6. Plant species composition was compared between 36 swamps of reference to moderately disturbed quality (0-8 total disturbance rank) and two highly disturbed (9) swamps. Only in these highly disturbed swamps did species composition begin to show variation from the typical swamps, with the addition of species such as rice-cutgrass (Leersia oryzoides) and duck weed (Lemna minor). In these sites hydrology has been significantly altered.

## Bird Community in Northern White Cedar Swamps

- Most abundant: Northern Waterthrush
-  Winter Wren
-   Canada Warbler,
-   White-throated Sparrow,Veery
-  Exclusive  to NWCS(not in Red maple):
- Yellow-bellied Flycatcher, Swainson’s Thrush, Dark-eyed Junco, Yellow-rumped warbler and Black-throated Green warbler

## Berlin Mall site

- BM site only cedar swamp with Song Sparrow
- Northern Waterthrush in all cedar swamps except Berlin Mall
- Northern Parula, Yellow-bellied Flycatcher, and Olive-sided Flycatcher absent from Berlin Mall site

## Conclusions:

- The metrics evaluated to date are not effective in distinguishing between reference and disturbed swamps, unless the swamp is highly disturbed.
- Breeding bird survey results show that differences in species composition and abundance reflect loss of suitable habitat through fragmentation and loss of swamp forest structure.

## New Directions

- Integrate with on-going stream and lake biological assessment sites
- Use existing methods for macroinvertebrate, fish and plant sampling
- Develop metrics for a Wetland IBI

## Stream associated wetlands

- Champlain lowlands
- Low-gradient, “slow winders”
- 10 sites
- Add to existing database
- New wetland biological database

## Lake and Pond associated wetlands

- Focus on draw-down sites and eutrophic sites
- Aquatic and wetland plants
- Macroinvertebrates
- Add to existing database
- New wetland biological database
- Select metrics for wetland IBI