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VERMONT WETLANDS BIOASSESSMENT

This study aims to evaluate the chemical, physical, and biological characteristics of seasonal pools and northern white cedar swamps in Vermont. It will assess sampling and assessment methods, classify reference conditions, and rank disturbance types. The study will also examine the impact of landscape quality on wetland condition.

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VERMONT WETLANDS BIOASSESSMENT

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  1. VERMONT WETLANDS BIOASSESSMENT

  2. 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

  3. 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

  4. 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 …..

  5. 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

  6. 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

  7. 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

  8. Water Sampling • Samples for chemical analysis • Field pH • Color • Alkalinity, Conductivity • Anions, cations, Aluminum • Lab pH

  9. Biological sampling • Aquatic macroinvertebrates • Algae • Amphibians • Vegetation

  10. Aquatic Macroinvertebrates • Funnel traps: swimmers • D-net scoops: benthic invertebrates • Qualitative: D-net sweeps

  11. Amphibians • Adults: species, presence/absence • Egg masses: species, counts • Spermatophores: counts • Larvae: species, counts

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

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

  14. 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%

  15. 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

  16. 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.

  17. Marsh Beetle pools • Cyphon sp. Indicator species • Smaller perimeter and watershed • Greater canopy cover • Tending towards moderate to mildly acidic

  18. 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

  19. 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

  20. Variability • Seasonal • Annual • Replicate samples • Methods • Chemical and physical

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

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

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

  24. 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)

  25. Vermont Wetlands Bioassessment Project Part 2 Northern White Cedar Swamps

  26. 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

  27. 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

  28. 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.

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

  30. 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.

  31. 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.

  32. 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

  33. 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

  34. 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.

  35. 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

  36. Stream associated wetlands • Champlain lowlands • Low-gradient, “slow winders” • 10 sites • Add to existing database • New wetland biological database

  37. 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

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