Page 698 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

662 part IV Soils, Ecosystems, and Biomes
▲Figure 20.21 Alpine tundra conditions. An alpine tundra and grazing mountain goats in the Canadian rockies. [robert Christopherson.]
hundreds of years. As growth in population and in energy demand continue, the region will face even greater challenges from petroleum resource develop- ment, including oil spills and the associated contami- nation, and landscape disruption.
Conservation, Management, and Human Biomes
In the early 2000s, biogeographers defined a new, emerg- ing scientific field called conservation biogeography. This subdiscipline applies biogeographic principles, theories, and analyses to solve problems in biodiver- sity conservation. Among the hot research topics in this field are the distribution and effects of invasive species, the impacts of rapid climate change on biodiversity, and the implementation of conservation planning and estab- lishment of protected areas. Focus Study 20.1 discusses specific efforts to preserve biodiversity, all of which are based loosely on the concept of natural biomes and prin- ciples of island biogeography.
Island Biogeography
for Species Preservation
When the first European settlers landed on the Hawai- ian Islands in the late 1700s, they counted 43 species of birds. Today, 15 of those species are extinct, and 19 more are threatened or endangered, with only one-fifth of the original species populations relatively healthy. In most of Hawai‘i, native species no longer exist below el- evations of 1220 m because of an introduced avian virus. This is one example among thousands of species extinc- tions and declining biodiversity across the globe. Island ecosystems are particularly vulnerable because their unique ecosystems evolved in isolation from mainland species.
Early explorers in the Atlantic Ocean saw remote islands as places to cut trees for masts and repairs and to obtain water and food supplies. Frequently, they released goats and rabbits on islands to proliferate and be a ready food source for future visits. These animals decimated native species populations, as did the introduced rats that attacked nesting birds. Today, restoration efforts on many islands include eradication of non-native species and the breeding of endangered native plant species in greenhouses and nurseries for reintroduction into natural island ecosystems (Figure 20.22). On some islands in the Atlantic, sci- entists found surviving native species, once thought extinct, growing on remote cliffs where they were re- trieved for breeding stock.
CRITICALthinking 20.3
A Shifting-Climate Hypothetical
Using Figure 20.7 (biomes), Figure 10.2 (climates), Figures 9.7 and 10.1 (precipitation), and Figure 8.1 (air masses), and noting the printed graphic scales on these maps, consider the following hypothetical situation. Assume a northward climatic shift in Canada and the United States of 500 km; in other words, imagine moving North America 500 km south to simulate climatic cat- egories shifting north. Describe your analysis of condi- tions through the Midwest from Texas to the prairies of Canada. Describe your analysis of conditions from New york through New England and into the Maritime Prov- inces. How will biomes change? What economic reloca- tions do you envision? Expand your thinking to another region of the world: If the subtropical high-pressure cell over Australia expanded and intensified, consider the new pattern of climate categories and ecosystems. •
Georeport 20.5 The Porcupine Caribou Herd
The Porcupine caribou herd is a population of tundra caribou that inhabit the Northwest Territories, yukon, and Alaska. Most of the herd migrates to the coastal plain on Alaska’s North Slope to calve in early June. The calving area is fairly small,
and 80%–85% of the herd uses it year after year. Oil exploration is not permitted in these areas because it degrades habitat and affects animal migrations. However, intense political pressure to relax any protection is ever present, and an aggressive campaign to overturn bans on exploration and drilling is active. The possibility of drilling for shale gas and methane hydrates is a new threat to the region.