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Chapter 5: Biomes and Biodiversity

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1 Chapter 5: Biomes and Biodiversity
Principles of Environmental Science - Inquiry and Applications, by William and Mary Ann Cunningham The following material is for Chapter 5 of ESC110 entitled Biomes and Biodiversity. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 No matter which way you look at it, the Earth is a big, beautiful and incredibly complicated system. This complexity is on a physical, chemical and biological scale. In this lesson, we will discuss some of the principles of living systems within this world we call Earth. If there weren't life on this planet the real image would appear very different than it does. In this figure, the green represents plant life, in oceans as well as landmasses. The Amazon rainforest has the most concentrated areas of plant life, and this area appears dark green. The eastern US and PNW are also dark green. The drier, less productive areas of the US are shades of yellow. The great deserts of the world are orange.

3 Part 1: Biomes Biomes Broadly defined life zones
Environments with similar climates, topographies, soil conditions, and biological communities Distribution mainly dependent on temperature and precipitation These come due to either latitude or vertical zonation Biomes are broadly defined life zones, with similar climates, topographies, soil and biology. (Notice the prefix bio- it means "life.")

4 ADD FIG. 5.1 The major factors determining the characteristics of biomes include temperature and precipitation. Life is affected either by a lack or an abundance of either. For instance, where there is very little moisture, there will be deserts, whether they are in warm or extremely cold areas (like the north slopes of Alaska). Where there are extremely low or very high temperatures, life is also affected. Some of the most productive and diverse ecosystems are the wettest and warmest, including the tropical rain forests.

5 Biomes of the World If you look on a very large regional scale, we can see some of the kinds of biomes that are found within the world. You can see that the coniferous, or boreal forests, of the PNW extend up into Canada and across Russia. Notice the deserts, generally outlined in a color similar to sand. Grasslands are found in temperate areas and the tropical rain forests are clustered near the equator.

6 ADD FIG. 5.4 If we look at the coupling between temperature and moisture in different biomes, we can see, for instance, that in Belem, Brazil, which is at the equator (latitude zero), there is very even temperature, but uneven precipitation. This region is pretty much non-seasonal except for the changes created by variation in precipitation, which accounts for the major differences throughout the year. Where we consider areas at higher latitudes (either northern or southern latitudes), we tend to get seasons like the ones we are used to in the Pacific Northwest. The most extreme ranges in seasons occur in interior areas in temperate zones. In Yuma, Arizona and Philadelphia, Pennsylvania, the variation is more than 20oC. Temperatures in Russia can range from –30oC (about -22oF) all the way up to 20oC (about 68oF) in one month. You might notice that an area with seasonal rainfall but relatively even temperatures is Bombay, India. Here, the average temperature hovers around 30oC. This area receives almost no precipitation throughout the year until the monsoon starts in May and continues through September or October.

7 Tropical moist forests
Abundant rainfall and warm constant temperature. Soil is thin, acidic and poor in nutrients Rich in biodiversity Most nutrients are contained in the biomes of living things

8 Tropical seasonal forests
Have wet and dry seasons Temperature is warm throughout the year. seasonal forests tolerant of dry seasons. Soil is richer than tropical moist forests.

9 Tropical savannas and grasslands
Low rainfall to support forests Routinely exposed to fire during dry season Plants have adapted to the long drought, fire and heat. They have persistent roots that continue after leave and stem die. Migratory grazers feed on the newly grown shoots

10 Deserts Very low rainfall Temperature could be hot or cold
Highly adapted plants live there. Organisms are adapted to conserve water. Water storing leaves and stems, tick epidermal layer Animals could be nocturnal and have minimized water loss

11 Temperate grasslands Grow in midlatitude
Moderate rainfall that can support grassland but not forests Rich soil made from organic matter of dead leaves.

12 Temperate shrublands Dry
Hot and dry summers and cold and moist winters. Drought adapted shrubs, trees and grass. Common plants include ever green shrubs with thick layers. Open to periodic fire that bring about succession The biome contains a big diversity of unique organisms

13 Temperate forests Evergreen or deciduous
Deciduous forests: plentiful of rainfall Broad leafed trees Live in midlatitude Shed leaf in the winter At lower latitude they are evergreen

14 Coniferous Forests Grow in a wide range of temperature and moisture
They grow mostly in dry habitats Thin waxy leaves adapted to conserve water They can also grow in wet coasts

15 Boreal forests Northern forest that lies between 50º and 60º north or mountainous area in lower latitude. Forest dominated by conifers, pines and cedar. And some deciduous plants as well.

16 Tundra Temperature below freezing for most of the year.
It’s a treeless landscape that occurs at high latitude or on mountain tops Resembles grassland or deserts. Less disturbed by human intervention because of harsh conditions

17 Arctic and Alpine tundra
Arctic: has short growing season and so low productivity Has short intense blooming time. Attracts migratory animals, specially birds. It’s important for global diversity specially birds. Alpine: occurs on mountaintops. Have similar environmental conditions as that of the Arctic tundra. Robust plant growth takes place during growing season Plants tend to have deep pigmentation and leathery leaves for protection against UV light.

18 So let's just move through the world here and consider some of the different kinds of biomes. This desert biome (Joshua Tree National Park) is one of my favorite areas because of its good rock climbing potential, especially in the winter. Joshua trees are the larger plants seen here. The vegetation here is adapted to low levels of moisture. This vegetation can handle severe and extended dry times with extremely high temperatures.


20 This spectacular black spruce forest in Alaska associated with the Chugach Mountains is an example of a coniferous forest biome. The trees shown in the foreground are able to grow to their full size because there is enough precipitation and warmth. However, notice that beyond the trees (at a higher elevation) is a sparsely vegetated area. Trees can't grow well here because precipitation drops off and temperature decreases. This forest gives way to tundra as altitude increases. The tundra ultimately grades into a total lack of vegetation on the tops of these mountains, where it is extremely cold most of the year. What we see here is that increases in altitude mimic the changes we see as latitude decreases. If we go farther north, we see the same kind of vegetation changes that we see on these slopes.

21 Marine Ecosystem Biological communities in oceans and seas
Most marine communities depend on photosynthetic organisms for energy source. Photosynthesis is greater at the coast lines due to accumulation of nitrogen and phosphorous Ocean currents also contribute to the distribution of biological activity by transporting nutrients and phytoplankton Ocean-bottoms depend on the surface organisms for food as they settle down. This could also be brought up to the surface. Vertical stratification is an important parameter. Determines light, temperature, and oxygen contents

22 Marine Ecosystems Open Ocean: has low productivity
Current drives nutrients and food that can support life in the open water Deep-sea thermal vent community: chemosynthesis (from sulfur compounds) by microbes that live on the ocean floor.

23 Tidal shores Support rich biological community
Coral reefs: Reefs are colonies of minute animals called coral polyps that live symbiotically with photosynthetic algae. The hard skeleton provides shelter for the algae. Coral reefs provide shelter for a lot marine animals as well. They require shallow and clear water. They don’t like nutritious water. Reefs can be damaged by coastal developments, fish, poisoning .

24 Mangroves Salt tolerant trees Grow on warm and calm marine coasts
Are source of food for marine and terrestrial animals. Provide shelter for juvenile fish, crabs and shrimps. Have been affected by human developments

25 Estuaries Bays where fresh water and salt water mix
Calm, warm, nutrient rich Biologically rich and diverse Emergent plants supported by the muddy bottoms. Different crustaceans Fish depend on them for juvenile development.

26 Tide pool Violent wave blasted shorelines
Flooded at high tide and retain some water at low tide Usually rock as wave action prevents sedimentation and plant growth. Cold flood at high tide and hot and dessicating sunshine at low tide makes hard for most species to live Has specialized but diverse plant and animal life.




30 Part 2: Biodiversity Biodiversity - the variety of living things - three types essential: Genetic diversity - variety of different versions of the same genes within a species Species diversity - number of different kinds of organisms within an ecosystem Ecological diversity - complexity of a biological community (number of niches, trophic levels, etc.) Adding to the concept of biomes, we now want to consider the concept of biodiversity (how varied living material is in a system). There are three basic kinds of biodiversity. The most commonly used is species biodiversity. However, within any species there can be a large or a relatively small amount of genetic diversity. For instance, let's consider two different species. First, let's take a species of wasp that feeds only on the pollen of one particular flower located in a very small part of a tropical rain forest. The wasp would die out if the flower were not present. The wasp is probably a species that exhibits a small amount of genetic diversity. We could also consider a species like Douglas-fir that is found all the way from British Columbia down to southern California. and also lives in two very different types of temperature and moisture regimes. For instance, it lives in both western and eastern Washington. Western Washington is cooler and wetter in the summer than eastern Washington, where it gets very hot and dry. We can conclude from its wide and varied distribution that Douglas-fir is a species with a lot of genetic diversity. We can also have ecological diversity, which consists of the niches or functions that species display within an ecosystem. If those are diverse, the system could be considered diverse as well. If we have a number of species that effectively do the same thing within an ecosystem, the ecosystem would not be as ecologically diverse as one in which organisms had a variety of ecological roles. It is easier to just count species as a measure of biodiversity, and this is probably why the common use of the term biodiversity refers to this measure.

31 How many species are there?
There are big questions in the study of biodiversity. Perhaps the biggest is just how many species there are. Some species are easily identified (flying birds, and plants such as Douglas-fir). Others, particularly small organisms that aren't easy to see, and organisms that live in environments that humans don't often visit, are much more difficult to count. In particular, if we take the insects, we find that they are incredibly diverse; and so it is very difficult to catalogue all of them. We have only scratched the surface of the number of species that exist, but we recognize that over a million species have been identified so far. This is probably only a fraction of the species that exist, particularly for poorly characterized organisms like insects and mites. The estimates for mammals and birds are stable (it is rare to discover a new species in these groups today), so there are probably fairly good estimates of the number of species that exist today. Another question that needs to be asked in making tallies of species is, "What exactly constitutes a species"?

32 Biodiversity Hotspots
Another big challenge, particularly if you think it is really important to preserve species (as most people do), is to identify biological hotspots (places where lots of species exist). These would be the areas that would receive the first efforts directed toward preservation and maintaining the species. I personally think concentrating on biological hotspots is important, but I think preserving biological hotspots while ignoring other areas with lower numbers of species yet with unique ecosystems is an absolutely terrible choice. In many cases, biologists say hotspots should be preserved first and preservation of other areas should come later. This means that if an organism does not live within one of these biological hotspots, it would get lower consideration when it comes to habitat preservation. Notice that many of these biological hotspots tend to be within tropical areas, and it is well known that tropical rain forests tend to have areas of high biological diversity. Notice, interestingly enough, that the Amazon is not an area of high biological diversity. This map shows an area in the interior of Brazil (the Brazilian Cerrado) that is more diverse than the Amazon, even though it is much drier than the Amazon. Similarly, the coastal areas of Atlantic forest of Brazil are more diverse, but not large areas of the Brazilian and South American Amazon. Most of the world's biodiversity concentrations are near the equator (tropical rainforests, coral reefs).

33 Part 3: How do we benefit from biodiversity?
Food Drugs and medicines Ecological benefits Aesthetic and cultural benefits Remember that people are generally selfish, so the question, "Why is biodiversity important to people?" is a fair one. Saying that we inherently want to protect biodiversity just because it is right only goes so far to convince people that it's important. In many cases, we can think of biodiversity as our breadbasket and a driver for economic output. For instance, many medicines have been discovered in plants, and people have learned to use them for various purposes (for instance, combating diseases). If plant species go extinct before we discover their potential uses, then it is a loss of a potential benefit. The next wonder drug (the one that might cure certain types of cancer) may be out there in nature. If we lose the species before we discover that benefit, then we have lost a lot. Different types of food also come from nature. Most of our important crops were wild species at one time, and then people discovered them and started domesticating them, a process that has taken place over hundreds of thousands of years. An increased and varied food supply is a benefit from these discoveries. The next slide shows a mangastein, a fruit from Indonesia. It is one of the best fruits you could ever eat. There is also another fruit in Indonesia that has a skin like that of a reptile, and it is just incredibly good. We do not even know of these fruits outside of Indonesia-- or at least I had never seen them. I had the opportunity of traveling throughout Indonesia, so I got keyed in on some of the wonderful species that exist within that country. They have the potential for being developed into economically important foods. If they go extinct, we would not have the opportunity to increase our food diversity and abundance. These are two selfish "people-centric" reasons – the potential for medicines and the potential for new types of food - that we should protect biodiversity.

34 Fig. 5.21 Here is a picture of the mangosteen, considered by many to be the world's best tasting fruit. Have you ever eaten one? If so, what do you think?

35 This table shows some important medicines that have been discovered in fungi, bacteria, and plants. Perhaps the most important, historically and even today, is penicillin. It was discovered in 1928, and was the first substance found that could stop bacterial infections. It is still a very effective antibiotic. (It is a common fungus (the penecillium fungus) that grows on bread.) Many other useful products (particularly antibiotics) have been discovered in plants and animals. All we have to do is find them and figure out how to exploit them.

36 Aesthetic and cultural benefits Bird watching and
other wildlife observation contribute more than $29 billion each year to the U.S. economy. Another major benefit of biodiversity for humans is that the diversity of nature actually lifts the human spirit and contributes tremendously to our enjoyment of life. Our enjoyment of life through being in nature has spawned an industry in and of itself. For instance, if we take Washington state as an example, we see that an enormous amount of money is contributed to the economy by people who come here to look at the biodiversity and the beauty of life (orcas, Douglas-fir forests, salmon, and so on.). The quality that outdoor recreation adds to the lives of people who come to Washington is worth more than the money spent by the state developing that recreation. In some cases, outdoor recreation is the largest part of a state's or country's economy. Ecotourism (tourism that supports the maintenance of things like biodiversity and helps to preserve the ecosystems within a country) has only scratched at the surface of its potential development. For instance, the Serengeti Plains of Tanzania and Kenya (a primo place to go as an ecotourist) have been preserved and ecotourism is the chief industry here. There would be no industry if people were unable to go and look at the enormous herds of animals on the Serengeti. There are other places in the world that have the potential for ecotourism to be developed in such a way that it doesn't disturb nature and can actually play a part in the preservation of nature. Unfortunately, in many cases tourism as it is practiced can actually have negative impacts on the environment of the ecosystem that you visit.

37 Part 4: What Threatens Biodiversity?
Extinction - the elimination of a species Natural process - one species lost every 10 years Process been accelerated by human impacts on populations and ecosystems E.O. Wilson - we are currently losing thousands of species a year In order to preserve biodiversity, we need to understand what affects it, and in particular what threatens it. We have tended to concentrate on species extinction as the most important aspect of biodiversity. What is even more important is the role that a single species may play in an environmental system. In some instances, other species might be affected by a single extinction, or the entire ecosystem might be affected as well due to the extinction. Even with that being said, it is very sobering to think that people would deliberately eliminate a species. More species exist now than have ever existed before; but there have been millions and millions of species that have gone extinct (including some things that I am glad we don't have around now such as Tyranosaurus rex and Velociraptors). These, however, died out from natural processes such as devastating natural events. We do know that human activities accelerate extinctions. E.O. Wilson, the famous contemporary evolutionary scientist, said that it is probably true that right now we are losing thousands of species per year, including many species that we wouldn't even know existed if it weren't for fossil records. The extent of human development and impact on populations, species and ecosystems is also accelerating over time, not decreasing.

38 Here is a list of some mass extinctions that occurred naturally in the past. Notice that the recent extinctions caused by human activity are more disastrous than many of the natural mass extinctions.

39 Part 5: Human-Caused Reductions in Biodiversity
Habitat destruction and fragmentation Hunting and fishing Commercial products and live specimens Predator and pest control Exotic species introduction Diseases Pollution Genetic assimilation There are many human activities that can have a negative impact on species and biodiversity, but particularly high on this list iis the destruction of a species' habitat. If we preserve habitat, typically the organisms will continue to exist, but this is not always true. If we change the nature of a habitat such that an organisms cannot migrate through it any more, we essentially isolate the animals from their habitats. Roads in particular are a problem because some species will not cross them. Even areas that have chains across them may be limiting migration. Migratory animals often will only migrate and move through their own particular kind of habitat. Commercial hunting and fishing can reduce biodiversity, and we are probably having a profound effect on salmon now by overfishing. Some species such as the North Atlantic cod went commercially extinct due to overfishing, (their numbers were reduced so drastically that they couldn't be fished anymore) but are responding now to protection. If you read the book Cannery Row by Steinbeck, you'll find that it talks about a town on the coast of California that was built entirely around capturing and processing anchovies. The anchovies were basically fished into commercial extinction. Capturing or using animal species as live specimens, especially when they have slow reproductive rates, can result in so many individuals taken out of the wild that those that are left cannot reproduce and maintain their numbers. Introducing (or in particular taking away) predators can have an adverse impact on other species. Introducing diseases can cause extinctions. An example is the American chestnut blight that caused the ecological extinction of the trees. Although there are still individual trees that you may see as you are hiking around the Appalachians, the species no longer has the distribution it once had - the American chestnut used to be the Douglas-fir of the eastern US. Pollution can adversely affect everything from a whale to a microbe. Also, reducing the genetic variability within a population can lead to extinction. For instance, cheetahs in Africa may go extinct, not because their habitat is gone, but rather because they have so little genetic diversity left in their relatively small population that they cannot adapt to natural changes in the environment.

40 Over hunting and habitat destruction caused its extinction.
About 200 years ago, the American passenger pigeon was probably the world's most abundant bird. Population: 3-5 billion Over hunting and habitat destruction caused its extinction. The passenger pigeon is often used as an example of a species that was hunted into extinction. When Europeans first came to America, the estimated population was between 3 and 5 billion. Very few bird species or any other organism for that matter would ever begin to have populations approaching that of the passenger pigeon. The birds depended on eastern hardwood forests for nesting sites and for food. When the pioneers cleared these forests for farmland, they destroyed some of the passenger pigeon's habitat, causing some decline in the population. But the greatest decline resulted from mass hunting carried out throughout the 1800s. The birds were killed and sold as food to city dwellers. Because they nested in large colonies, they were easily captured in great numbers. Millions of passenger pigeons were killed every year. This had a big impact on the passenger pigeon and the 3 to 5 billion pigeons that originally seemed limitless was completely eliminated, and the passenger pigeon became extinct.

41 Trade in Products from Endangered Species
When I lived in Tanzania, I got to witness an example of how trading products from animals can impact rare species. In the Ngorongoro Crater near where I lived, there is an abundance of wildlife, and it is a famous place to visit as a tourist. I traveled there once because I had heard about a young rhinoceros that had been born, and everybody was quite exited about this; yet, when I finally got there I found that it had been killed. It hadn't been killed intentionally. What happened was that a light plane flew into the crater, landed, and then poachers got out and shot the mother to take its horn. The younger rhinoceros kept charging the hunters, and they shot it too so they could go and saw off mother's horn. Two rhinos were killed to provide a single rhinoceros horn that the hunters flew away with before anyone could do anything about it. That rhinoceros horn was probably ground to powder and sold in Asian markets as an aphrodisiac. The belief that rhinoceros horn is an aphrodisiac is ridiculous since the powder from the horn has no effect. You can see here a number of different animal products including horns, skulls and genitalia (normally the male part) from different animals. Most of the trading in these products is done underground. Whatever you do, don't ever buy this kind of stuff since doing so would just be contributing to the problem.

42 Trade in Wildlife Some trade in wildlife, particularly those that are not endangered and are abundant, can potentially maintain the habitat. That doesn't include trade that relies on the use of cyanide and dynamite as shown in this slide. These materials would destroy the habitat of the animal being collected. For instance, the American alligator was threatened with extinction only a few decades ago, but nowadays this species has recovered and has become a pest. There is a new legal trade in alligator pelts in which the money obtained from the sale of their pelts goes back into protecting their habitat. This trade model, if expanded to other species, could help maintain a variety of important habitats. Thus, animal trade is not necessarily always a bad thing if it leads to the preservation of habitat. About 75% of all saltwater tropical aquarium fish sold come from coral reefs of the Philippines and Indonesia, where they are commonly caught with dynamite or cyanide.

43 Part 6: Protecting Biodiversity
Hunting and fishing laws The Endangered Species Act (ESA) Recovery plans Reintroductions Minimum viable population Private land and critical habitat Reauthorization of the ESA International wildlife treaties These are the various ways in which society tries to protect biodiversity. For instance, when the majority of people obey laws, sport hunting and fishing are not going to threaten biodiversity. Hunting can actually have a positive impact, as 10 percent tax is collected on equipment and ammunition, and this tax goes to habitat conservation. The Endangered Species Act of 1973 mandates protection when a species is threatened with extinction. Maintaining a minimum viable population has actually been accomplished in some cases with species recovery plans. There have been a number of salmon recovery plans, unofficial and official, large and small. When the California condor dropped to dangerously low numbers, a very controversial plan was undertaken. A number of California condors were captured, their eggs were taken and incubated and allowed to hatch, and the young birds were reintroduced into the wild. As a result, the population increased. Nowadays it is considered that the number of condors that survive naturally along with the ones that have been introduced is sufficient to maintain the populations. Particularly important is protecting habitat and the land and water systems of species. The Endangered Species Act expired in 1992, and after much debate, it was modified and reauthorized despite a number of attacks and votes on reconsideration. Today, it continues to be one of the major ways that biodiversity is protected in the US. In addition to the Endangered Species Act, we have the potential to use international treaties to protect biodiversity. For instance, a worldwide ban on the sale of ivory has helped protect African elephants that have large tusks. (In some cases, though, wildlife officials would like to be able to sell ivory to provide revenue to protect elephants.) Bans on things like the utilization of rhinoceros horns have also helped, but the key is to get society to say it is not going to buy the horns. Once this happens, we can focus on other problems such as adequate habitat that a species needs to recover and sustain itself.

44 This slide shows the number of endangered and threatened species worldwide that are listed by the US Fish and Wildlife Service. You'll notice that hundreds of species of animals and plants are presently listed as endangered or threatened. This shows that the potential for extinction of many of these species is there. Many of their problems are being addressed, but many are not.

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