Amphibian and bird assemblages at hardwood bottomland restoration sites in western Tennessee

Transcription

1 Amphibian and bird assemblages at hardwood bottomland restoration sites in western Tennessee

2 Hardwood Bottomlands (HBL) Forested wetlands in floodplains Highly productive ecosystems Historically common in MAV Currently, >70% of original HBL destroyed

3 Ecological Functions of HBL Environmental Filter contaminants Flood control Produce biomass and sequester carbon Wildlife Habitat Birds Amphibians Fish Mammals

4 Restoration Wetlands Reserve Program (WRP) Established under 1990 farm bill by USDA NRCS Voluntary program for landowners Retires marginal agricultural land from production Tree replanting Currently 809,440 ha nationwide $227,631,300 in 2007 alone Tennessee Began restoration under WRP in 1994 Currently 13,541 ha enrolled in TN >90% HBL Replanted 2004

5 Monitoring Currently no monitoring protocol for WRP Important to ensure restoration goals are reached Primary goal of WRP: ecological function of HBL Priority: habitat for migratory birds

6 Goals Quantify state of ecological restoration Compare biological characteristics of restoration sites to reference sites Develop models for monitoring ecological restoration in HBL

7 Study Sites 16 Randomly selected restoration sites 1 st year of restoration ( ) Mar Aug 2008 Size (7.7 ha to ha) 4 Reference sites located in Hatchie River watershed Longest unchannelized tributary of Mississippi River Restoration sites Reference sites

8 Sampling Plot Placement Two plots at each site minimum 250 m apart Located in highest and lowest contours OR >100m >250m tributary One plot at center of site sites too small for 250 m separation

9 Methods

10 Communities Surveyed: Birds Amphibians Quantify ecological complexity Compare between restoration and reference sites

11 Amphibian Composition Sampled 2x per month Mar August ) Call surveys Recording devices at one random plot per site 5 min segments 0.5, 2.5, 4.5 hours after sunset Call index (1 3) assigned to each species

12 Amphibian Composition 2) Treefrog Tubes Sampled 2x per month Mar August 2008 Two 6.4 cm diameter PVC tubes at each plot

13 Amphibian Composition Sampled 2x per month Mar August ) Cover Boards Two pairs of 0.56 m 2 plywood boards placed at each plot

14 Amphibian Composition Sampled 2x per month Mar August ) Area Searches Two quadrants searched, twice per month Searched in zigzag pattern for 15 minutes or until 100 m was reached

15 Recorders Treefrog tubes Cover boards Area search Amphibian Sampling Design

16 Bird Composition Point Counts Morning after amphibian recorders put out Ten minute count Each plot 4 Distance bands 0 10 m m m m Sampled 2x per month Mar Aug 2008 Recorded all individuals observed 0 4 min 4 6 min 6 10 min Photo by Ron Erwin

17 Analysis Response variables Birds: Relative abundance of families, feeding substrate guilds and nesting guilds Used linear regression to quantify the relationship (α = 0.05) between restoration age and response variables Birds and amphibians: Shannon Weiner diversity index Species richness

18 Results: Amphibians Diversity and richness not significantly different among restoration ages P= Salamanders found only at reference sites

19 Results: bird diversity and richness Significant relationships between restoration age and both Shannon Wiener Diversity and Species Richness P= P=0.0001

20 Results: bird abundance Abundance of 10 of 24 most common families related to age of restoration in >1 seasonal period Abundance of all 4 feeding substrate guilds related to age of restoration Feeding substrate air March April May June July August Positive bark Positive Positive Positive canopy Positive ground Negative (p=0.0640) Negative

21 Results: bird abundance Nest location March April May June July August cavity/crevice Positive Positive ground/ herbaceous vegetation nest parasite shrub/vine/ bramble Abundance of 4 out of 6 feeding substrate guilds related to age of restoration in >1 seasonal period Negative Negative tree branch Positive Positive Positive tree twig Positive Positive Positive

22 Conclusions Except for salamanders, HBL restorations support amphibian diversity and richness comparable to reference sites Bird use of restoration sites is different from reference sites Bird and amphibians may be useful biological metrics for developing methods of monitoring BLH restorations

23 Future Analyses Use metrics of plant, amphibian and avian communities to develop IBI models that quantify ecological function in hardwood bottomlands. Develop predictive habitat models that relate vegetation and abiotic characteristics of restoration sites to ecological complexity of the amphibian and avian communities.

24 Acknowledgements Dr. Matthew J. Gray Dr. David A. Buehler Dr. James Fordyce Dr. Thomas H. Roberts Luke Owens Mike Zeman (NRCS) Bobby Mimms (NRCS) Mike Chouinard (Hatchie NWR) Jason Maxedon (TWRA) Mike Pitts (TN State Parks) Dr. Robert Hayes (WTREC) Funding: Agriculture Wildlife Conservation Center (NRCS) The Nature Conservancy

25 Photo Credits Brenda Carroll Ron Erwin Matthew J. Gray Tim Baerwald Greg Lavaty John White Jacob S. Spendelow Lang Elliot Vladimir Ivanov Nathan Banfield Terry Hibbitts Walter W. Knapp