Ch 11 Habitat Loss/ Invasives Section 03 Section 04

C. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: Habitat destruction, degradation, and fragmentation Invasive species Population growth Pollution Overharvest

Habitat fragmentation leads to species vulnerability to predators, disease One in six species of birds are threatened with extinction due to habitat loss and fragmentation Nonnative species are the 2nd greatest threat to birds Species are limited in their ability to colonize new areas, find mates and food

Mountain Lion Habitat Fragmentation The map shows Fragmented Local Forest in Southern California Why would a Mountain Lion attack Humans? PLAY NEWS VIDEO

Commercial hunting and poaching Habitat degradation and fragmentation Habitatloss Overfishing Pollution Commercial hunting and poaching Habitat degradation and fragmentation Climate change Introducingnonnative species Sale of exotic petsand decorative plants Predator and pest control Secondary Causes • Population growth • Rising resource use • No environmental accounting • Poverty Figure 11.7 Natural capital degradation: underlying and direct causes of depletion and premature extinction of wild species. The major direct cause of wildlife depletion and premature extinction is habitat loss, degradation, and fragmentation. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems. Basic Causes Fig. 11-7, p. 229

Birds are excellent environmental indicators because they live in every climate and are easily tracked Birds help to control rodents and insects, pollination of flowering plants, seed dispersal

Case Study: A Disturbing Message from the Birds The majority of the world’s bird species are found in South America. Threatened with habitat loss and invasive species. Figure 11-10

INVASIVE SPECIES Many nonnative species provide us with food, medicine, and other benefits but a a few can wipe out native species, disrupt ecosystems, and cause large economic losses. Show news report video on kudzu Kudzu vine was introduced in the southeastern 1930’s U.S. to control erosion. It has taken over native species habitats. Figure 11-A

INVASIVE SPECIES Many invasive species have been introduced unintentionally. Figure 11-11

SEA LAMPREY It is thought that improvements to the Welland Canal in 1919 allowed its spread from Lake Ontario to Lake Erie, and while it was never abundant in either lake, it soon spread to Lake Michigan, Lake Huron, and Lake Superior, where it decimated indigenous fish population in the 1930s and 1940s Sealamprey are parasites they will eventually kill the trout.

Asian Long-horned Beetle Believed to have been brought over in the wood of crates Trees favored by the Asian Longhorned Beetle are predominantly maples Currently, there is no known chemical or biological defense against the Asian Longhorned Beetle and, in North America, they have few natural predators. The damage is caused by beetle larvae which burrow deep within a tree to feed on its food and water conducting vessels.ﾊ Continued feeding causes structural defects and eventually kills the life-sustaining cambial layer by girdling.ﾊ Mature beetles then burrow out of the tree leaving holes the diameter of ball-point pens.ﾊ Heavy Asian Longhorned Beetle infestations can kill otherwise healthy adult trees.

Show the video on how africanized bees where introduced to the americas. Threats to natural capital: some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Fig. 11-11, p. 234

They have no natural predators, competitors, or pathogens in their new habitat They can trigger ecological disruptions, such as the wild African honeybee Some have become genetically resistant to pesticides through natural selection

INVASIVE SPECIES The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. Most probably from ships. Aggressive nonnative species that has eliminated about 90% of native ant species. Figure 11-12

FIRE ANT ATTACK! PLAY YOUTUBE VIDEO Have video of fire ants taking away larvae from other colonies. PLAY YOUTUBE VIDEO

INVASIVE SPECIES Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread. Figure 11-13

Ecosystems Vulnerable Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived • High dispersal rate • Release growth-inhibiting chemicals into soil • Generalists • High genetic variability • Climate similar to habitat of invader • Absence of predators on invading species • Early successional systems • Low diversity of native species • Absence of fire • Disturbed by human activities Figure 11.13 Threats to natural capital: some general characteristics of successful invasive species and ecosystems vulnerable to invading species. Fig. 11-13, p. 236