Modules 9 - 14

You and a friend are having a debate about how biomes should be defined. She thinks consumers should be equally as important as plants in defining a biome, while you think plants should be the most important biotic factor. What statements below are accurate and support your side of the debate?

-Climate is the most important abiotic factor for defining biomes, and the dominant types of plants in a region depend primarily upon the region's climate. -Plants are the basis of all terrestrial life and therefore the species of consumers that inhabit a biome depends directly on the plant community.

Select all of the following statements that are true for the rank abundance curve shown below?

-Community a is dominated by one species. -In community b, each species is represented equally compared to the rest of the species. The rank abundance curve for community b shows that all five species are equally abundant, while the rank-abundance curve for community a shows its dominance by the most abundant tree species. Both communities show the same level of diversity with 5 species in each.

Chapin and colleagues (1994) have described the change in soil properties during succession at Glacier Bay, Alaska. What soil properties increase during succession?

-Nitrogen -Organic matter content -Soil moisture

Which of the following describes primary succession?

-No plants, animals, or microbes present -Bare ground, no soil -Occurs after a volcanic eruption -Occurs after glacier retreats

Which of the following describes secondary succession?

-Supports life immediately after a disturbance -Occurs after a fire -Occurs after a tornado -Soil present -Severity varies, but it is never completely lifeless

Identify the results obtained by Orrock, Witter, and Reichman that support their hypothesis that the relationship between Brassica nigra and Nassella pulchura is apparent competition.

-The distribution pattern between Brassica nigra and Nassella pulchura suggest competition. -B. nigra actually suppresses N. pulchra indirectly by sheltering mammalian herbivores that feed on the native grass. Orrock, Witter, and Reichman concluded that while the distribution patterns suggest competition, B. nigra actually suppresses N. pulchra indirectly by sheltering mammalian herbivores that feed on the native grass.

Fill in the blanks 1. Moderate annual rainfall, pronounced dry season, variation in annual temperature 2. Very abundant annual rainfall, relatively stable year-round temperatures 3. Summer is hot and dry, winter is moist with cool temperatures for most of the year, periodic fires 4. Moderate annual rainfall, alternating dry and wet seasons, moderate variation in annual temperature, fire is common 5. Low annual precipitation from 200 to 600 mm, permafrost, short summer season with soggy ground, grasses, mosses, and lichens dominate 6. Annual rainfall varies from 300 to 1000 mm, cold winters and very warm summers 7. Annual precipitation between 600 to over 3000 mm, cold winters with snowfall and warm summers 8. Very low annual precipitation, prolonged seasonal drought conditions 9. Highly variable seasonal precipitation and temperatures depending on altitude 10. Annual precipitation from 200 to 600 mm, long winter and short summer seasons, often large annual temperature range, landscape dominated by evergreen conifers

1. Tropical Dry Forest 2. Tropical Rain Forest 3. Mediterranean woodland and shrubland 4. Tropical Savanna 5. Tundra 6. Temperate Grasslands 7. Temperate Forest 8. Desert 9. Mountains 10. Boreal Forest

Complete each sentence with the correct term. 1. Some of the precipitation that falls over land immediately . 2. Clouds are formed as water vapor cools and condenses. The process that creates water vapor is . 3. Precipitation over land can be used by as a source of water. 4. The major source of water for groundwater is . 5, Much of the precipitation that falls on land creates that returns water back to the ocean. Word Bank: consumers, evaporates, evaporation, glaciers, lakes and rivers, precipitation

1. evaporates 2. evaporation 3. consumers 4. precipitation 5. lakes and rivers

Complete each sentence with the correct term. 1. The production of new organic matter or biomass by autotrophs in an ecosystem is called . 2. The amount of biomass produced over an interval of time is the . 3. Primary producers represent the trophic level position in a food web. 4. All organisms depend on primary production for their existence.

1. primary production 2. rate of primary production 3. first 4. consumer

Examine the processes of ecological community change by completing each sentence. Then, arrange the sentences in a logical paragraph order. 1. The gradual change in plant and animal communities following disturbance or the creation of new substrate, is a process known as ecological . 2. Ecologists define two types of succession. When an existing community has been disturbed and organisms slowly reestablish in the area, such as when plants become reestablished in a wooded area that has been cleared, succession is occurring. 3. On the other hand, succession can begin on areas of bare rock or where soil has not been formed. 4. The first species to inhabit an area undergoing such primary succession form a community. 5. Given enough time and lack of disturbance, primary succession ends with a community, whose populations remain relatively stable and are characteristic of the region. Word Bank: climax, extinction, keystone, pioneer, primary, secondary, succession

1. succession 2. secondary 3. primary 4. pioneer 5. climax

A community has four species, two with 20 individuals and two with 30 individuals. What is the value of the Shannon-Wiener index?

1.366

Which research project will give the most accurate estimation of species diversity within the community and produce a more complete lognormal curve?

A sampling of a 5 acre plot of tropical rainforest that discovered 279,200 individuals.

Which combination of soil nutrients and their corresponding levels has been found to create distinct growing conditions that allowed for a stable coexistence of phytoplankton species?

A stable coexistence of phytoplankton occurred when the levels of phosphate and silicate were in balance with each other.

Which of the following organisms tend to dominate areas in which phosphorous is a limiting factor?

Algae

Grimm attributes most nitrogen retention by the Sycamore Creek ecosystem to uptake by algae and invertebrates, since levels of nitrogen retention are consistent with the rates at which nitrogen was accumulated by algal and animal populations. What conclusion can you draw from looking at the graph of nitrogen retention in Sycamore Creek after flooding?

Algae and other invertebrate populations reached peak levels around 30 days after flooding, then began to decline.

Earth's climatic variation is due to

All of the choices are correct

Which of the following is true about farmers using ants as keystone species to reduce pest populations in agricultural ecosystems?

Ants control the population of large bodied citrus pests China has been controlling insect pests of orange orchards for over 17 centuries

What type of relationship is exemplified by a graph showing the relationship between soil fertility and plants species that have a mycorrhizae relationship?

As the soil fertility of the community decreases, the diversity of plant species plants with mycorrhizae relationships found within the community will increase.

Which of the following ocean zones is described as the bottom of the ocean

Benthic

Which statement about intertidal zone disturbance is correct?

Boulders of medium size will experience the greatest degree of diversity due to having an intermediate level of disturbance.

Which soil horizon is the bottom layer that consists of weathered parent material from bedrock?

C horizon

Studies of which nutrient cycle have been able to provide society with crucial information regarding global climate change?

Carbon A passion for nutrient cycles is no longer limited to academic circles but now energizes people of all walks of life from around the world. This shift in interest is driven mainly by the looming consequences of our having dramatically altered some key nutrient cycles. The best known of these human-driven changes is the current imbalance in the carbon cycle that has resulted in a buildup of carbon dioxide in earth's atmosphere, accompanied by global warming.

Which of the following is true about the deep-sea hydrothermal vents?

Chemosynthesis rather than photosynthesis provides energy at the base of the food web.

Identify the geologic feature that most affects community resilience in Sycamore Creek.

Distribution of bedrock

Contrast the movement of energy and nutrients in ecosystems.

Energy is not recycled within ecosystems, whereas nutrients are used over and over.

Which environmental variable describes the mangrove habitat?

Estuarine Intertidal Tropical

Complete each sentence with the correct term. Word Bank: facilitation and inhibition, facilitation, inhibition

Experiments manipulating species during succession of the intertidal zone by Sousa show evidence of inhibition of later successional species. Turner's studies of intertidal plants and algae indicate evidence that facilitation is important during succession of the intertidal zone. Keever's experiments on the temperate forests of the Piedmont Plateau indicate that facilitation and inhibition are important mechanisms of succession during early succession.

As air descends it cools down and picks up moisture, making the air more humid.

FALSE

Increased primary production fosters lower secondary production in terrestrial and aquatic ecosystems

FALSE

Terrestrial primary production is limited only by precipitation.

FALSE

As the nutrient retentiveness of a stream increases, the spiraling length of nutrients increases.

FALSE The tendency of a stream ecosystem to retain nutrients is called nutrient retentiveness. In stream ecosystems, retentiveness is inversely related to spiraling length. As the nutrient retentiveness increases, the spiraling length decreases because of the increased tendency to retain nutrients.

Which of the following is described as pioneer species modify the environment in such a way that it becomes less suitable for themselves and more suitable for species characteristic of later successional stages?

Facilitation model

A mountain range along the east coast of a continent will have a dry microclimate on its eastern-facing slopes.

False

Cold air holds more moisture than warm air.

False

Warm, wet air circulates away from the equator as dry cool air comes up behind it.

False

Complete the following sentences about the nitrogen cycle. Word Bank: Nitrogen fixation, Nitrification, Denitrification, Ammonification

In this anaerobic process, bacteria convert N2 to ammonia, a form of nitrogen more readily used by plants. Nitrogen fixation In this process, bacteria convert ammonium to nitrate. Nitrification This anaerobic process releases N2 from the organic matter pool to the atmosphere. Denitrification This process is the most common pathway for nitrogen to enter the soil by fungi and bacteria during decomposition. Ammonification

Which of the following is described as early occupants of an area modify the environment in a way that makes the area less suitable for both early and late succession species?

Inhibition model

Based upon this diagram, what type of hypothesis can be formed in regard to species diversity?

Intermediate levels of disturbance promote higher levels of diversity

Which of the following ocean zones is described as shallow shoreline that occurs between low and high tide?

Intertidal

How does emphasizing strong interactions make the structure of food webs more comprehensible?

It emphasizes the more biological significant trophic interactions and simplifies food web structure.

Identify the statement that best describes the key difference between a keystone species and a foundation species.

Keystone species have a low level of biomass within the community while foundation species have a high level of biomass.

During the __________ stage of succession in Glacier Bay there is a net inhibitory effect on spruce seedlings.

LATE

Choose the answer that best describes a trophic cascade.

Lake trout are introduced into a lake and reduce the abundance of the native cutthroat trout that feed on small zooplankton. This results in an increased abundance of small zooplankton.

Which of the following traits are associated with eutrophic lakes?

Low oxygen High density of algae Can result from runoff or dumping of nutrients (e.g. fertilizers)

Which environmental variable describes the coral reef habitat?

Marine Tropical Subtidal

Using the following species rank-abundance curves for caddisflies of pond and mountain stream habitats in northern Portugal (data from L.S.W. Terra), which community has greater species richness and evenness?

Mountain steam

Which of the following ocean zones is described as from the coast to the margin of the continental shelf?

Neritic

How do the soils of Hawaiian ecosystems change over very long periods of time, that is, over the course of millions of years? Group of answer choices

Nitrogen losses from these ecosystems increased over time, while phosphorus losses decreased.

Coriolis effect causes winds in the

Northern Hemisphere to deflect to the right.

Which term is used to describe the dynamics of nutrients within a stream ecosystem?

Nutrient spiraling

Which soil horizon is the upper layer that has loose and highly fragment litter layer?

O horizon

Which of the following soil horizon profiles is ordered correctly?

O, A, B, C

What is the biggest reservoir of the hydrologic cycle?

Oceans

The feeding activities of a keystone species may control the structure of communities. Paine (1966, 1969) proposed that keystone species affect community structure in specific directions. Complete each sentence with the correct term describing his research.

Paine predicted that some predators may INCREASE species diversity in intertidal communities. This outcome is predicted because some predators REDUCE the probability of competitive exclusion by lower trophic levels.

Paine proposed that feeding activities of a few species have inordinate influences on community structure. To test his hypothesis, what trophic level did he manipulate in the intertidal zone of Mukkaw Bay, Washington and New Zealand?

Paine removed the top predators.

Which of the following nutrient cycle studies are playing prominent roles in science today?

Phosphorous, Nitrogen, and Carbon

In pristine, tropical surface marine waters, what factors limit primary productivity? Check all that apply.

Phosphorus & Nitrogen

Chapin and colleagues (1994) have described the change in soil properties during succession at Glacier Bay, Alaska. What soil properties decrease during succession?

Phosphorus content pH Bulk density

Which of the following statements best explain the difference between gross primary production and net primary production? Check all that apply.

Plants utilize some of the incoming energy derived from photosynthesis for their own self-maintenance. Plants and algae carry out both photosynthesis and cellular respiration.

Which set of results would support the hypothesis that the interaction between Brassica nigra and Nassella pulchra is actually direct competition?

Researchers found a gradient of decreasing herbivore pressure away from B. nigra patches, producing a gradient of increasing density in the N. pulchra population with distance from B. nigra patches. Orrock, Witter, and Reichman propose that B. nigra patches provide areas of protective cover for the small mammals in their study area from which they forage across the surrounding landscape. The result is a gradient of decreasing herbivore pressure away from B. nigra patches, producing a gradient of increasing density in the N. pulchra population with distance from

Annual Actual Evapotranspiration (AET) is positively correlated with net primary productivity in terrestrial ecosystems.

TRUE

As air rises in the atmosphere it cools down.

TRUE

Based on the study by Peierls et al. 1991 of 42 major river systems, as human population density within river basins increases, the concentration and export of nitrate increases.

TRUE

Grasslands have higher net primary productivity compared to tundra.

TRUE

Studies of nitrogen retention in the Hawaiian Islands and Sycamore Creek both found a similar pattern of increasing retention early in succession followed by decreasing retention later in succession.

TRUE

The rate of decomposition within an ecosystem affects the rate at which inorganic nutrients are made available for use by primary producers.

TRUE

Two sides of a mountain range can have very different climate and plant communities, even at the same elevation and latitude.

TRUE

Warm air rises.

TRUE

When air cools down it releases moisture in the form of precipitation.

TRUE

Ecological efficiency can limit the number of trophic levels in an ecosystem.

TRUE Ecological efficiency can limit the number of trophic levels in an ecosystem. As energy is transferred from one trophic level to another, energy is lost due to assimilation, respiration, and heat production. As losses accumulate between trophic levels, eventually there is insufficient energy to support a viable population at a higher trophic level.

Identify the effects that habitat disturbance by humans has upon diversity.

The biodiversity of a region tends to decrease as a result of habitat disturbance. Climate change is causing many species to be pushed into extinction. The Arctic sea ice is melting at a faster rate, reducing the hunting ground available for polar bears. The water quality of rivers and streams is decreasing, leading to a drop in fish biodiversity. All of these are effects that human disturbance of habitat has upon diversity.

Which statement about the N:P ratio of aquatic vertebrates is correct?

The higher the phosphate content in the body of the organism, the lower the N:P ratio and the lower phosphate levels in their excretions.

Choose the statement that best describes the results of the study of species richness of bird communities along a gradient of land use intensity by Blair (2004).

The highest species richness of birds occurred at intermediate levels of land use intensity.

Complete each sentence with the correct term. The number of species in a community is called ______. The relative abundance of species in a community is called ______ . A combination of the number of species and their relative abundance defines _________.

The number of species in a community is called species richness. The relative abundance of species in a community is called species evenness. A combination of the number of species and their relative abundance defines species diversity.

Meyer and Likens (1979) studied the long-term dynamics of annual phosphorus inputs and exports of Bear Brook in New Hampshire. Complete each sentence based on results of their study. Word Bank: deforestation, greater, less, stream discharge

The ratio of annual phosphorus inputs to exports varied from 0.56-1.6 and varied depending on STREAM DISCHARGE. During high flow years the phosphorus export was GREATER than inputs. During low flow years, the phosphorus export was LESS than inputs.

What is necessary in order for a species to be considered a foundation species?

The species must have a substantial influence on the community structure as a consequence of its high biomass.

Identify the correct changes to spiraling length if V and T both decreased.

The spiraling length would be shortened. Spiraling length is related to the rate of nutrient cycling and average velocity of nutrient movement downstream. Denis Newbold and his colleagues (1983) represented spiraling length, S, as:S = VT where V is the average velocity at which a nutrient atom moves downstream and T is the average time for a nutrient atom to complete a cycle. If velocity, V, is low and the time to completea nutrient cycle, T, is short, nutrient spiraling length is short.

Which of the following is described as initial stages of colonization are not limited to a few pioneer species, juveniles of species dominating at climax can be present from the earliest stages of succession, and species colonizing early in succession do not facilitate colonization by species characteristic of later succession stages?

Tolerance model

Tropical rainforests near the equator are characterized by high levels of annual rainfall and relatively constant annual temperatures.

True

Identify after which disturbance primary succession occurs. Check all that apply.

Volcanic eruption Glacial retreat Primary succession occurs on newly exposed geological substrates not significantly modified by organisms, for instance, on newly formed volcanic lava or on substrate exposed during the retreat of a glacier.

Which of the following describe the coral reef?

Warm tropical water with penetrating sunlight High biodiversity of aquatic organisms

Complete each sentence about interactions between beavers and the leaf beetle, Chrysomela confluens. Word Bank: benefited, higher, indirect commensalism, lower, not repelled, repelled

When activities of one species indirectly benefit another species without itself being helped or harmed, this is an example of indirect commensalism Where beaver foraging activity was was greatest, beetle densities were higher. Beaver are repelled by the defensive leaf chemistry of felled cottonwood tree leaves Leaf beetles are not repelled by the defensive leaf chemistry. The leaf chemistry of sprouted cottonwood leaves leaf beetles benefitted and explains higher densities on beaver felled trees.

Which statement best describes how the beavers indirectly benefited the leaf beetle?

When the beavers cut down the cottonwood trees they caused the tree stumps to secrete defensive toxins that the beetles could use for their defensive mechanisms.

Climatic diagrams provide all of the following information except

Wind patterns

What conclusion can be drawn about the relationship between foliage height and warbler diversity from this graph?

With an increase in the volume of foliage there is a corresponding increase in the number of species of warblers.

Diversity indices such as the Shannon-Wiener index, are

a measure of the numbers of species and the relative abundance of each species.

The dominant abiotic factors influencing the structure and distribution of organisms in terrestrial biomes are

average annual temperature and precipitation.

A region of the southwest United States has experienced an extended period of dry weather that has resulted in the loss of agricultural crops and reduced water levels of local streams and rivers, threatening the water supply. This description is an example of __________.

drought

Winds moving south from the equator are pushed to the ____ because of the Coriolis effect. The direction of the Northeast trade winds is from _____. As observed from the earth's surface in temperate latitudes, the predominant wind direction is from the ______.

left northeast west The Coriolis effect is a phenomenon caused by the rotation of the earth, which produces a deflection of winds and water currents to the right of their direction of travel in the Northern Hemisphere and to the left of their direction of travel in the Southern Hemisphere. The direction of the Northeast trade winds in the Northern Hemisphere is from the northeast. Within the temperate belt, the winds are observed mainly from the west.

Most of the earth's deserts are

located at 30° north and south latitudes.

Studies of succession of diatoms, birds, plants, and macroinvertebrates have shown that diversity tends to increase in a(n) __________ manner over time.

logartithmic

The conversion of a substance from the organic form to the inorganic form is called __________.

mineralization

At the equator, air rises which creates a

moist tropical climate.

A foundation species is best defined as

organisms, such as abundant, forest tree species or coral reef species, that substantially influence community structure as a consequence of their abundance.

Ratio-dependent predator-prey models predict

that primary consumer abundance will increase proportionally to the level of enrichment.

Community ecology is best defined as the study of

the association of interacting species in a defined area.

Mineralization is best described as

the breakdown of organic matter from organic to inorganic forms during decomposition.

The relative abundance of a wide variety of organisms approximates a lognormal distribution. For most of these distributions, only a portion of the bell-shaped curve is apparent because

the sample sizes are relatively small.

Seasonal shifts between winter and summer in the higher latitudes is caused by the

tilt of the Earth's axis where summer occurs in the hemisphere tilted toward the sun.

Heating of the earth's surface causes

warm air to rise and cool air to sink.