Talk will be available at Lab Website

Google: Skelly Yale

Global Amphibian Decline

Take Home Points

• Upland Conversion Eliminates Amphibian Populations

• Isolation Fosters Extinction

• Most Amphibians Are Specialists– Successful conservation requires a diversity

of dynamic wetlands

Context Matters.

Yale Forest Tolland Manchester

0.3 inds / ha* 1.3 inds / ha 7.8 inds / ha

85% Forested 78% Forested 37% Forested

5% Impervious 8% Impervious 20% Impervious

Species Disappear from Developed Wetlands

Skelly Unpublished

Lost DiversityAcross 60ConnecticutWetlands

0

1

2

3

4

5

6

Undeveloped Suburban Urban

Landscape

Sp

ecie

s p

er W

etla

nd

Gibbs 2000

Land Conversion: Wetland Size & Isolation

Land Conversion: Wetland Isolation

Gibbs 2000

Land Conversion: Wetland Isolation

Gibbs 2000Gibbs 2000

Fragmentation: ‘Rural’ to Urban

Transect 10 x 2 km

Orange, CT295 People/sq km

Milford, CT846 People/sq km

Gibbs 1998

Fragmentation: ‘Rural’ to Urban

Gibbs 1998

Fragmentation Leads to Local Extinction

Gibbs 1998

Species LossIn Intact ForestPatches

Species Differ

Species are frequently missing from vernal ponds in deforested landscapes

Homan et al. 2004

% of pondsoccupied by spottedsalamanders ishigher when uplandsare intact forest

Isolated Wetlands are less likely to have persistent amphibian populations

0

100

200

300

400

500

600

Never Invaded Extinct Stable

Population Status

Isol

atio

n [m

]

Skelly et al. 1999

Whole Pond Experiment: Yale-Myers Forest

Manipulated canopy in 6 wetlands in late 2001then monitor population & community Responses

At each wetland: ca. 25 overstory stems removed on S upland

Canopy & Temperature

Open

Closed

10

13

16

19

0.0 0.2 0.4 0.6 0.8 1.0

GSF

oC

Reduced Canopy Tends to Increase Number of Species

Skelly Unpublished

Following Cutin late 2001,new specieshave tended to move intoCut ponds.

Altered Canopy Does Not Affect Wood Frog Abundance

Skelly Unpublished

Following Cutin late 2001,wood frogshave remainedabundant

Spotted Salamanders May be Even More Abundant with Altered Canopy

Skelly Unpublished

Following Cutin late 2001,spotted salamandersmay have Increased.

Amphibians as Canopy Specialists

Threshold – Most SpeciesGeneralist – Few Species

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1

Average Light Level (GSF)

% W

etla

nd

s P

rese

nt

Most species that can tolerate low light can occupy more wetlands

Data for 8 Species

Spotted Salamander

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1

Average Light Level (GSF)

% W

etla

nd

s P

rese

nt

Marbled Salamander American Toad

Closed Canopy Specialist Open Canopy Specialist

Canopy Generalist

No single wetland typeprovides habitat for allamphibian species

How can we conserve Wetland Dwellers?

• Protect Wetland and Upland Units

• Develop Proactive Landscape Level Plans

• Avoid Use of Mitigated Wetlands– Bigger is not better– Stormwater catchments are typically poor habitats

• Allow/Foster Wetland Dynamics– Wetland Diversity in Space and Time– Beaver– Selective Cutting

Take Home Points

• Upland Conversion Eliminates Amphibian Populations

• Isolation Fosters Extinction

• Most Amphibians Are Specialists– Need a diversity of dynamic wetlands

Context Matters.

Amazon.com Sales Rank:

#202,658

References• Gibbs JP 1998. Distribution of woodland amphibians along a forest fragmentation gradient

Landscape Ecology 13: 263-268.

• Gibbs JP 2000. Wetland loss and biodiversity conservation Conservation Biology 14: 314-317.

• Halverson, M. A., D. K. Skelly, J. M. Kiesecker, and L. K. Freidenburg. 2003. Forest mediated light regime linked to amphibian distribution and performance. Oecologia 134:360-364.

• Semlitsch RD 2000. Principles for management of aquatic-breeding amphibians Journal of Wildlife Management 64: 615-631.

• Semlitsch RD, Bodie JR 2003. Biological criteria for buffer zones around wetlands and riparian habitats for amphibians and reptiles Conservation Biology 17: 1219-1228.

• Semlitsch, R. D. and D. K. Skelly. 2007. Ecology and conservation of pool breeding amphibians. Pages 127-148 in Vernal Pools: Ecology and Conservation of Seasonal Wetlands in Northeastern North America (A. Calhoun and P. deMaynadier, Editors). CRC Press. ISBN 0849336759

• Skelly, D. K., E. E. Werner, and S. A. Cortwright. 1999. Long-term distributional dynamics of a Michigan amphibian assemblage. Ecology 80:2326-2337.

• Skelly, D. K., M.A. Halverson, L. K. Freidenburg, and M. C. Urban. 2005. Canopy and amphibian biodiversity in forested wetlands. Wetland Ecology & Management. in press.