1. The Biodiversity Crisis – WHAT’S CAUSING IT??? Part 1
Human impacts
Habitat Alteration
Destruction
Fragmentation
Degradation
Overexploitation of species

2. I. Human Impacts – Population growth correlated to biodiversity crisis
Endemic Bird Areas and Centers of Plant Diversity in Forests
I. Human Impacts – Population growth correlated to biodiversity crisis

4. From a sustainability perspective, when humanity's Footprint exceeds the amount of renewable biocapacity a draw down in natural capital is required and this is considered unsustainable.

5. II. Habitat alteration

6. A. Habitat destruction Deforestation - GOING, GOING GONE?
150,000 – 210,000 km2 lost per year

8. B. Habitat Fragmentation

9. 1. Island biogeography theory paved the way for understanding fragmentation effects
Biogeography = the study of distributions of organisms, both past and present, and of related patterns of variation over the earth in the numbers and kinds of living things
Where do species occur, why do they occur there, and where are the greatest concentrations? 
Island theory:

11. I.B.T. applied to fragments – size matters - Probability of common forest interior neotropical migrant birds nesting in mid-Atlantic forests of various sizes

12. Hyperabundance phenomenon
Animal populations “trapped” on small & medium sized islands have high population densities – WHY?
Reduced competition?
Reduced predation?

13. Predictions based on I.B.T.
Compression hypothesis = on islands, as more species invade & are packed into the landscape, the niche occupied by each species becomes smaller
Filtering hypothesis = reduction in the # of species during dispersal
Stepping stone hypothesis = smaller islands that lie between the main recipient island & its mainland colonizing source increase the rate of exchange

14. The I.B.T. & Conservation larger areas are better than smaller ones
one large habitat area is better than several smaller ones of equal total area
closely spaced habitat patches are better than widely spaced ones
habitat patches arranged at equal distances from one another are better than those arranged in a linear sequence of increasing distance from the first patch to the last
connected patches are better than unconnected patches
a circular patch is better than a noncircular patch

15. 2. Fragmentation = Formerly continuous natural habitats broken up due to the encroachment of civilization
2 components of habitat fragmentation:

16. Habitat fragmentation affects patch size, quality & connectivity

17. A constellation of separate habitat patches may be critical to the survival of individuals or populations

18. Biological consequences of fragmentation
Initial exclusion
Crowding effect
Insularization and area effects
Isolation
Edge effects
Matrix effects
Road problems
Species invasions
Ecological processes

20. Natural edge areas are important
Inherent edges are usually long-lasting features of the landscape related to:
Topographic differences
Soil type shifts
Presence of open water
Or geomorphic factors (peaks, ridge-crests)

21. The problem with unnatural edges:
Abrupt edges alter the microclimate conditions - resulting in changes in plant community composition, mortality rates, regeneration processes

22. Anthrophogenic fragmentation/edges
Anthropogenic edges
Alter patterns of local diversity
Population dynamics

23. Edge effects can cause some species to thrive, whereas others perish -
2 Brown-headed Cowbird eggs in a Blue-winged Warbler's nest
Deforestation brought the cowbird into contact with naive populations of potential hosts, many of whom have not yet had time to evolve strategies for dealing with brood parasitism.
Edge effects can cause some species to thrive, whereas others perish -

24. Edge habitat Core habitat -
% of quail nests preyed upon as a function of distance from forest edge
Edge habitat
Core habitat -

26. Review: Fragmentation Results in
-isolated fragments -
Edge effects:
-alters microclimate
-increase temp, decrease humidity

27. Species vulnerable to fragmentation
Wide-ranging species
Nonvagile species
Species w/specialized requirements
Large-patch or interior species
Species w/low fecundity or recruitment
Species vulnerable to exploitation

28. Iberian lynx, hunted to near extinction
Grizzly Bear – wide ranging, 70 to 400 square miles
Green Sea turtle – low reproductive capacity, takes years
Checkerspot butterfly – poor disperser, needs serpentine native grasslands

29. C. Habitat degradation

30. Acid precipitation, ozone depletion
NOx & Sox emissions
HCl and ClONO2

31. 4). Climate Change Greenhouse effect in full swing!
Reproduction cycles shifting: birds, frogs
Alteration in vegetation composition

33. CO2 EMISSIONS BY SECTOR AND DEVELOPMENT: 1990-2003 in Scandinavia

34. III. Overexploitation of species
Commercial harvesting
Bushmeat crisis
Collectors