Extinction’s New Face:

Habitat Loss & Fragmentation

What is the evidence of habitat loss?

• Deforestation…

Sour

ce: w

ww

.gua

yaki

.com

/inde

x.ph

p?p=

refo

rest

atio

n

Deforestation…

• Is it only limited to the Amazon?

How does species abundance relate to habitat size?

• Make predictions• Is there likely to be a relationship?• Why or why not?

What are the impacts of decreasing habitat size?

• We call this habitat fragmentation• Are there likely to be any additional problems,

beyond simple reduction in area?

Over time large blocks of forest (green) are fragmented through a variety of land use activities (after Curtis, 1956) - Cadiz Township, Wisconsin.

Habitat Fragmentation & Edge Effects

Mean alien species richness, summarized by transect position and aspect. Sample size = 7 for each combination of transect and aspect. Redrawn from Brothers and Spingarn 1992). (http://dnr.state.il.us/orep/inrin/ecosys/forests/forstres.htm )

Mean frequency of sample transect segments containing alien species (bottom), summarized by transect position and aspect. Sample size = 7 for each combination of transect and aspect. Redrawn from Brothers and Spingarn (1992).   (http://dnr.state.il.us/orep/inrin/ecosys/forests/forstres.htm )