ch04 Ecology and Geology

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105

Ecology and Geology

This stream in the mountains of southern California has deep

cool pools that form in part because of the large boulders that

converge flow, causing scour. The processes of scour produce the

pool which is an important habitat for trout.

Learning Objectives

Ecology and geology are linked in many fasci-

nating and important ways. These linkages and

their utility in restoring environments such as

rivers, wetlands, or beaches are emphasized in

this chapter. Important learning objectives are

Know some of the basic concepts of ecology and linkages to geology

Understand the importance of relationships

between geology and biodiversity

Know what factors increase or decrease

biodiversity

Know what human domination of ecosys-

tems is and how we can reduce the human

footprint on the environment

Know why we need an appropriate environ-

mental ethic on a time scale relevant to

people today

Know what ecological restoration and the

processes of restoration are



106 Chapter 4 Ecology and Geology

Endangered Steelhead Trout in SouthernCalifornia: It’s All About Geology

Coastal streams that emerge from southern California moun-tains and flow into the ocean are not commonly thought of astrout habitat. Steelhead trout are born in mountain streams

and travel to the ocean where they remain for several years before returning to spawn. These fish are more commonly as-sociated with streams of the Pacific Northwest. Nevertheless,populations of steelhead trout exist from San Diego in fur-thermost southern California north to south of San Franciscowhere they merge with their more northern relatives.

Southern California has a semiarid climate and streamflow is extremely variable. Lower parts of streams often dryup in the summer and much of the entire stream may dry upduring drought years that occur periodically. In wet years,especially following wildfires, floods with large amounts of sediment are common. Headwater streams following wildfireor landslides may become choked with gravel that in subse-quent years spreads through the system, providing importanthabitat for fish and other aquatic species.

Summer low flow is particularly important to southernsteelhead, which are an endangered species. Adults enter thestreams from the ocean during winter months to spawn andmay return to the ocean to spawn again in future years. Theeggs hatch in the gravel of the stream and young fish reside inthe stream for a period ofmonths to a year or sobeforethe urgeto go tothe ocean moves themto migrate.As part ofa study toevaluate the steelhead habitat in the Santa Monica Mountainsnear Los Angeles, several stream systems were observed dur-ing the summer low-flow months. One of the goals as part of aplan to recover endangered southern steelhead was to identify

which streams in the Santa Monica Mountains were mostcapable of supporting steelhead trout. Several of them, includ-ing Malibu Creek and Topanga Creek, were known to have

steelhead. Geology of the Santa Monica Mountains was foundto be an important factor in enhancing the summer low flowthat is the major limiting factor for steelhead survival in south-ern California. Where aquifers are present and groundwater isforced to the surface due to rock fractures or faults, seeps andsprings are more common. It was found that on the scale of theSanta MonicaMountains theeastern portion of therange offershigher potential for summer low flow due to favorable geol-ogy. As a series of offshore faults come on land and cross thestreams, more abundant summer low flow occurs. The faultsform a barrier to groundwater, forcing the water toward thesurface where it emerges as seeps and springs. During the latefall of 2005 a number of pools were observed in TopangaCanyon (Figure 4.1) and no fish were observed in most of thepools. In two or three pools where fish were observed, seepsand springs from fractures and faults in the sedimentary rockswere clearly providing a source of cold water. The pools wereat places where rock banks and large boulders were in thechannel. The rocks and boulders constrict the channel, pro-ducing a zone of fast water at high flow that scours a pool,providing a low-flow habitat for fish.

The study of the Santa Monica Mountains suggests that itis important to consider geologic factors in streams whenassessing fish habitat. In southern California it is clear that thegeology and groundwater are important in understandingfish habitat.

CASE HISTORY

4.1 Ecology for Geologists: Basic Terms

Ecology is the study of controls over the distribution and abundance of livingthings. More generally ecology is the study of living things (organisms) and theirinteractions and linkages to each other and to the nonliving environment. Thenonliving environment is largely controlled by physical and chemical processesrelated to the geologic cycle (see Figure 3.13). The complex interactions betweenlife and the broader environment are responsible for the creation and maintenance

of our living world. Geologic processes from the global to the regional down tothe smallest scales, such as a rock under which a lizard lives, greatly affect lifeprocesses.

Discussion of relationships between ecology and geology starts by defining afew terms and principles. These include species, population, ecological commu-nity, habitat, and niche. Following these definitions, we will turn our discussion toecosystems where geology plays a full role in partnership with life. A species is agroup of individuals capable of interbreeding. Population may be defined as agroup of individuals of the same species living in the same area. The ecologicalcommunity is a group of populations of different species living in the same areawith varying degrees of interaction with each other. We use the term habitat to de-note where a particular species lives; how it makes a living is known as its niche.

For example, think about a mountain lion in the mountains of Montana. We say



Ecology for Geologists: Basic Terms 107

Figure 4.1 Fish habitat: It is about geology This pool in Topanga Canyon is at a site wherefractures and faults cause springs that introduce cold water into the stream system.Without this cold water there would be much less habitat for the endangered southern steelhead. (Edward A. Keller)

the habitat is the mountains, but the niche of the mountain lion is eating deer andother large mammals.1

Before leaving our discussion of some of the basic terms of ecology we will briefly consider types of species. Some species are considered to be indigenousin that they are found in the area where they evolved. Others are exotic species

brought into an area or region by humans for a variety of purposes or as acciden-tals. For example, acacia trees were brought to the United States and planted aswind breaks in arid regions. Two varieties of eucalyptus trees from Australia have

been imported and widely planted, as have been numerous other plants and ani-

mals from around the Earth. Most exotic species when introduced do not causeproblems, but some do. Sometimes we refer to problem exotic species as invasivespecies. These species will compete with indigenes species and may displacethem. Some invasive species are brought in accidentally due to transporting mate-rial around the world, whereas others are brought in intentionally. In either case,negative aspects of invasive species are often not anticipated. Introduction of invasive species is one of the major reasons for the extinction of plants andanimals around the globe.

Two other terms that are useful are biosphere and biota. The biosphere is the partof Earth where life exists and biota refers to all organisms living in an area or regionup to and including the entire Earth. With these basic definitions behind us, wewill consider what an ecosystem is, types of ecosystems, relations between geol-

ogy and biodiversity, and human domination of ecosystems.




What Is an Ecosystem and How Does It Work?An ecosystem is an ecological community and its nonliving environment in whichenergy flows and chemicals (such as nutrients and water) cycle. Thus the ecosys-tem is geology, chemistry, and hydrology and functional linkages with life aremany and complex. The basics of this are shown in Figure 4.2, and it’s importantto remember that energy flows through ecosystems where chemicals are recycled

and used numerous times. Sometimes we refer to “ecosystem function,” which isrates of flow of energy and cycling of nutrients or other chemicals through anecosystem. In addition to ecosystem function, other characteristics are structure,process, and change. Ecosystem structure includes two parts: the community of organisms and the nonliving (geologic) environment. The two main processes of ecosystems are energy flow and chemical cycling. Finally, succession is an orderlyand sometimes not so orderly change of species as an ecosystem evolves followinga disturbance such as volcanic eruption, flood, or wildfire. If the disturbanceresults in a new land surface such as new land added by volcanic eruption to anisland, the succession is called primary. More commonly disturbance involvesreestablishment of existing ecosystems following disturbance and is calledsecondary succession. Secondary succession often involves plants that are calledpioneers because they can do well with a lot of light and grow quickly. With time,

as more nutrients are cycled and the system develops, the middle stage of succes-sion occurs; this is characterized by the greatest number of species and their abili-ty to use energy and cycle material. The later stages of succession are dominated by fewer species, and in a forest we say these are the old growth. The popular ideaof a “balance of nature” with orderly succession to a climax condition where littlechanges and the system is in equilibrium is an imaginary condition and a concept

Figure 4.2 Ecosystem basics Idealized diagram showing the basics of an ecosystem in terms of energy flowing and chemicals cycling. (Edward A. Keller)



Geology and Biodiversity 109

largely rejected by ecologists. Disturbance and change on a variety of scales of time and space are the norm.1

There are several types of ecosystems, including indigenous, natural, humanmodified, and human made or constructed. Completely natural indigenousecosystems on land are hard to find because human activity has been so pervasiveor invasive that almost all ecosystems have been modified by human use andinterest. For example, some of the waste of our society, such as lead that is emitted

into the atmosphere, is transported around the planet, affecting all ecosystems itcomes into contact with, often far from human populations.

Some ecosystems, over a wide range of sites and purposes, are constructed byhumans. For example, we may construct shallow ponds or a series of canalsknown as bioswales that collect runoff of surface water. Marsh plants, such as cat-tails, when planted in ponds or canals, use and remove nutrients in water that’sdelivered to them as a waste or pollutant, helping clean the water. Speciallydesigned wetland ecosystems have been constructed where bacteria and plantsprocess mine wastewater and help remove toxins from water. Other large-scaleecosystemsare constructed to partiallytreat urban wastewater. Human-constructedecosystems are part of what is known as biological engineering.

Natural Service Functions of EcosystemsEarth is a suitable place to live because the environment produces the necessaryresources that living things need to survive. As one of the many species on Earth,we extract resources and receive the benefits of natural service functions fromecosystems (also called ecosystem services). By natural service functions we meanthose processes of ecosystems that are responsible for producing clean waterand air as well as the mixtures of plants and animals that are necessary for oursurvival. For example, ecosystem services help cycle elements through the envi-ronment, provide nutrients to plants, remove pollutants from water, and throughsoil fertility allow for increased crop production.

Natural service functions may include buffering functions such as protectionfrom natural hazards such as landsliding and flooding. For example, plants onsteep slopes contribute to soil stability through the interaction of growing rootsin the soil that increases the strength of slope materials and provides protectionfrom failure by landslide. The roots, especially those with a diameter about thesize of a pencil’s, bind the soil together much like steel bars in concrete. Similarly,plants on the banks of a stream provide a root mass that stabilizes the soil andhelps retard stream-bank erosion. Fresh or saltwater marshes provide a buffer thatabsorbs wave energy and energy from winds. Coastal marshes protect againstcoastal flooding and also helps reduce coastal erosion.

We have grown accustomed to the natural service functions that the ecosystemsof Earth provide. On the other hand, we sometimes change the land and reduce oreliminate these service functions. For example, when we remove coastal marshes,we are more vulnerable to coastal erosion and flooding from storms such as hurri-

canes that occasionally strike the coastline. When we drain marshes and wetlandsalong rivers, we reduce their ability to store water and as a result increase theflood hazard.

4.2 Geology and Biodiversity

Biodiversity is an important concept in environmental science. Most commonly,when we think about biodiversity, we are discussing the number or abundance of species in an ecosystem or ecological community. The number of species is oftenreferred to as species richness whereas the relative proportion of species in an




ecosystem is referred to as its species evenness. Another term sometimes encoun-tered is dominant species, which is the species or multiple species that would bemost commonly observed in an ecosystem. Plant ecologists use the concept of importance value of a species or multiple species to an ecosystem. The importantprinciple with respect to biodiversity is that geology influences biodiversity fromthe smallest scale on a hill slope to continental-scale features such as a mountainrange.

Biodiversity of Trees in North America and EuropeA fascinating and interesting relationship between geology and biodiversity at thecontinental scale is the distribution and number of native tree species in NorthAmerica versus Europe. North America has many more native species of treesthan are found in Europe and the hypothesized reason is related to linkages

between the ice ages, glaciers, and plate tectonics that determine the orientation of mountain ranges. In North America, the major young mountain ranges run gener-ally north–south and include the Rocky Mountains and the mountains of the WestCoast. In Europe the dominant young mountain ranges resulted from the collision

between the African and European plates that produced the Alpine range in Spaineast through the Himalayas (Figure 4.3). So how might this be related to the

number of species of trees in North America and Europe?The Last Glacial Maxima about 20,000 years ago, when glacial ice covered about

30 percent of the continental area, was a harsh environment for trees. As the conti-nental glaciers grew in North America and Europe, the trees had to migrate in frontof the advancing ice. In North America, they found corridors to migrate to thesouth, but in Europe they were blocked by the east–west Alps that were glaciated.In Europe the trees became trapped between the glaciers and many more species

became extinct than in North America. Thus, we see the biodiversity of native treesin North America and Europe was significantly affected by continental-scalemountain building related to plate tectonics.2

Figure 4.3 Major young mountains on Earth A map showing the major young mountain ranges.Notice mountain ranges in North America are roughly north–south and the major mountain ranges in

Europe, the Alps and Himalayas, are much more east–west. (Edward A. Keller)

Europe

Africa

India

Young Mountians

N

N America





Figure 4.4 Wolves and streams

(a) Willows along Blacktale Creek inthe spring of 1996 are nearly absentbecause of heavy browsing by elk.(Yellowstone National Park) (b) Following reintroduction of wolves only six yearsearlier, thicker stands of willows areclearly evident. (William J. Ripple)

Figure 4.5 Ecosystem processes with and without wolves Diagram showing processes that occur with and without wolves for streams in Yellowstone National Park. Without wolves, extensive browsingby elk degraded this stream environment which has recovered since wolves have been reintroduced.(Modified after Ripple, J. W., and Beschta, R. L. 2004.Wolves and the ecology of fear; can predation risk structure

ecosystems? BioScience 54(8): 755–766)

Without Wolves With Wolves

Wolves not present (1926–1995)

Elk browse on woody species(aspen, cottonwood, and willow)

on stream banks

Decreased abundance of stream sidespecies (aspen, cottonwood, willows,

and others)

Loss of riparianfunctions

Loss of beaverLoss of food web

support forother stream side

plants and animals

Channel erosion and widening,loss of wetlands, loss of connection

between streams and adjacentfloodplains

Wolves restored (post-1995)

Elk adjust to predation risk

Increased recruitment of woody browse species

Recovery of stream functions

Recoveryof beaver

Channels stabilize, recovery of wetlands and stream hydrology

Predators

Prey

Plants

Otherecosystemresponses

Recovery of foodweb for other stream

side plants andanimals


(a) (b)



Coastal Geology, Kelp, Urchins, and Sea OttersThe kelp forests in southern California (Figure 4.7) are a remarkable ecosystem based in part on the local geology. Kelp are a type of large marine alga that growsincredibly fast. The giant kelp of southern California can grow up to more than25 cm per day, reaching a height of over 10 m above the sea floor. The three partsof the kelp plant include the rootlike holdfast, stem (stipe), and system of blades(leaves). They also have a number of flotation devices near the blades so they willremain in an upright position in the water column. At the surface, particularly atlow tide, the sea surface looks like a nearly solid mat of kelp. Below the surface theforest consists of stipes, which are attached to the bottom by the holdfasts. Theholdfast is attached to boulders or the rocky bottom. Some of the rocky environ-ments to which they may become attached are wave-cut platforms found offshorein fairly shallow water and rock reefs, which may have water depths of up to

several tens of meters. The wave-cut platform has variable relief depending uponthe local resistance of the particular rock shelf. Rock reefs often result fromgeologic uplift from faulting or the presence of more resistant (hard) rock. FromSanta Barbara south to Los Angeles these structures are parallel to shore androughly east–west. Nearly all the offshore reefs that support kelp forests owe theirexistence to an active geologic environment.

Holdfasts are attached to the rocks with what looks like a root system but it doesnot take up nutrients. Rather, the function of the holdfast is to hold the plant inplace. If the holdfast breaks loose or is destroyed by some process, the kelp willfloat free and drift to the shore. During storms the kelp moving near the surfacewill apply stress to the lower plant, causing the holdfast to come loose. The hold-fast, with bits of rock, may be transported to the beach to become part of the

sediment carried in the near-shore environment. This process can move rock

Figure 4.6 Wolves are natural predators of elk in Yellowstone National Park and their reintroductionhas benefited stream ecosystems in unexpected ways. (Tom McHugh/Photo Researchers, Inc.)

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Figure 4.7 The kelp forest of

southern California is a remarkably diverse ecosystem. Geology plays animportant role in the development of the kelp forest, in which the plantsare attached to the ocean bottom inrelatively shallow water of wave-cutplatforms or uplifted rock reefs.

(Flip Nicklin/Minden Pictures)

particles from offshore to the beach, while distributing organic material fromoffshore to the beach.

The kelp forest flourishes in areas of upwelling nutrients and relatively coldwater. Growth rates are greatly reduced in years when the marine water warmsup, as, for example, during El Niño years when warmer water is present. There isa variety of organisms near the bottom of the kelp forest, including urchins, whichare spiny animals that feed on the holdfast of kelp. When urchins feed and breakthe holdfast, the kelp will float free and die. There are several predators of seaurchins, including humans, who collect them for their eggs, or roe, which isvaluable, and sea otters, who eat the urchins (Figure 4.8).

Studies conducted in Alaska suggest that those areas that no longer havemany otters are impoverished. In some areas, the sea urchins are so plentiful thatkelp scarcely exists. Where sea otters have been restored to their former rangeafter they were nearly exterminated for their valuable fur, the kelp returns and

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flourishes.1 Linkages between the geologic environment, kelp forest, urchins, and

sea otters are idealized in Figure 4.9. Notice that when sea otters are present thereare fewer urchins and more abundant kelp.Sea otters are a keystone species with a strong community effect because when

they eat sea urchins, they make it more likely to have a healthy kelp forest. The kelpforest and exposed rock provides the structure and food resources for otheranimals including fish. Sea otters have no interest in protecting kelp and they don’thang around at the base of the kelp keeping the urchins off. However, through theirfeeding on urchins, sea otters help ensure a healthy, productive kelp forest.1

There is currently a controversy about whether sea otters should continue toexpand into their previous habitat in southern California south of Pont Concep-tion, northwest of Santa Barbara. The conflict results because people harvesturchins and fishermen are afraid that if sea otters become abundant, the numberof urchins will be reduced to the point that it will not be profitable to harvest

them. The sea otters, of course, are unaware of this controversy and are simplymoving back into their historic habitat. If the sea otters are allowed to migratesouth, their reestablishment will be a slow process and in fact may not occur for avariety of reasons. First and foremost, the coastal waters in some areas of southernCalifornia are polluted and pollutants may sicken the sea otters. Also, the climateis changing and ocean waters are warming, which may make the southern regionsof the habitat less viable for kelp forests and the urchins that feed on kelp hold-fasts. In addition, sea otters are sensitive to water temperature. They have high fatdensity that provides good insolution in cold water, but can result in overheatingin warm water.

Our discussion of wolves in Yellowstone and sea otters in the kelp forest andtheir relations to the hydrologic and geologic environment is fairly straightforward.

Figure 4.8 Sea otters and the kelp forest Sea otters are a keystone species of the kelp forest.They feed on urchins and other shellfish. (FRANS LANTING/MINDEN PICTURES)

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There are numerous other examples of how keystone species affect ecosystems.For example, American bison through their grazing practices helped maintain

biodiversity of the tall grass prairie and the soil where they roamed (Figure 4.10).Some species that are not large individuals or highly visible in their ecosystems

have large importance from an ecologic perspective. For example, reef-buildingcoral and algae are species that create physical habitat in the coral reef environ-ments of the world. The coral and algae provide the framework upon whichother reef life exists (Figure 4.11). Due to warming of the oceans, pollution, andoverfishing, coral reefs around the globe are in decline in many places. Finally,ancient coral reefs are present as limestone rock that forms the foundation of many areas where people live, including much of Florida and the GreatLakes area.

Factors That Increase or Decrease BiodiversityFollowing our discussion of ecological communities, ecosystems, and keystone

species, we can more directly address what sorts of processes are likely to either

F a u l t

Rockreef (geologic environment)(a)

0

10

20

30Lowtens/m2

(b) (c)

highhundreds/m2

without sea otters

o c e a n d e p t h ( m )

with sea otters

other shellfish

sea otter

urchin

urchin kelp

kelp forest

holdfast

0

10

20

30

0 25 50 75 100

withoutseaotters

o c e a n d e p t h ( m )

withsea otters

sea urchin densitypercent kelp cover

Figure 4.9 See otters affect kelp forest Idealized diagrams showing the effects of sea otterson the kelp forest and in particular the abundance of kelp. (a) The geologic environment with upliftedrock reef, kelp, urchins, and sea otters. (b) Without sea otters the density of urchins is high. (c) With seaotters the percent of kelp cover is high. Notice when sea otters are absent, there is a large reductionin the kelp.



increase or decrease biodiversity. We are primarily concerned with speciesrichness, that is, the number of species, but biodiversity also relates to geneticdiversity, which is the number of genes found in the population that may notalways be expressed by the morphology or function of the particular organism.

What Factors Increase Biodiversity?Biodiversity maybe increased by several factors1 including

Presence of diverse habitat with many potential niches. For example, a riverwith variable depth, turbulence, velocity, and amount of large woody debris(stems and rootwads of trees) will support more species.

Figure 4.10 American bison

greatly influenced the tall grass

prairie that they roamed across asthey grazed.Their grazing habithelped maintain the biodiversityof the prairie grasses and the entirelandscape, including soils and wetlands known as buffalo wallows.

(Lowell Georgia/Corbis)

Figure 4.11 Coral reefs are

composed of a number of organisms

including algae and corals, which buildup the basic reef structure that greatly affects biodiversity of the marineenvironment. (Cousteau Society/

The Image Bank/Getty Images)

Geology and Biodiversity 117



Moderate amounts of disturbance, such as wildfires, violent storms, orvolcanic activity, that provides new or renewed habitat.

Presenceof harsh environments, such ashotsprings or nutrient poor rocksandsoil may have specialized species that increase diversity at the regional scale.

Relatively constant environmental factors such as temperature, precipitation,and elevation. This is one of the reasons why there are so many species near

the equator. There is a relatively constant supply of energy from the sun nearthe equator and conditions such as temperature and humidity are relativelyconstant, leading to greater diversity of organisms.

Evolution, or generation of biodiversity, which generally refers to slowchanges over geologic time in organisms. However, sometimes evolutioncan occur rapidly with some species.

An environment that is highly modified by life, as, for example, rich organicsoil. At regional scales more biologically productive areas tend to be morediverse.

Geology, which affects ecosystem function and process from small- tocontinental-scale environments. See, for example, the earlier discussion of

biodiversity and orientation of mountain ranges.

What Factors Reduce Biological Diversity?Biological diversity may be reduced1 by

Presence of extreme environments, as, for example, hot springs or tar seepsthat locally provide a much more limited set of habitats and niches for life.From above we see that extreme environments may increase biodiversity atthe regional scale. Thus the effect changes with scale.

Extreme disturbance, or very frequent disturbance such as regional-scalefires, storms, or volcanic activity that catastrophically disrupt ecosystems.

Transformation of the land, which fragments ecosystems. For examples,

above and below a dam on a river that block migration of fish, constructionof a large reservoir that leaves a series of small islands isolated from themainland, and urbanization of a region with few corridors between rurallands for migration of plants and animals.

Presence of environmental stresses, such as pollution.

Habitat simplification, for example, agriculture that reduces habitat andconstruction of engineering structures to control flooding or erosion (see ACloser Look: Seawalls and Biodiversity).

Introduction of exotic, intrusive species that compete with indigenousspecies or cause predation or disease in indigenous species.

Presence of mountain ranges that block or restrict migration of plants and

animals.

Human Domination of EcosystemsIt is apparent that we dominate almost all ecosystems on Earth. Study of this dom-ination has led to the general conclusion that the domination has not yet produceda global disaster. However, in some areas disastrous conditions have occurred.What is apparent is that there are many factors that are linked in complex ways tohuman population increase as well as transformation of the land for human useand global change in climate and the biogeochemical cycles. These processesare resulting in the reduction of biological diversity, including the loss of entireecosystems and the extinction of many species. We are apparently in a large







The Golden Rule of the Environment: A GeologicPerspective All About TimingStephen Jay Gould, a famous geologist and ecologist, stated that a proper scien-tific analysis of the environmental crisis facing people today requires the use of anappropriate scale of time and space. Gould argues that there is “Earth time”(deep

time), which is basically geologic, and then there is “human time,” which is very

Steep offshore slope

Effects of a seawall over time

Eroding beach:Biodiversity is high; life in ocean, ,and on sand, sea birds, .

HT

LT

Waves are deflected:Beach is narrower; biodiversity isreduced for beach animals includingshore birds.

Biodiversity is greatly reduced.

A. Before

Steepening of offshore slopeHT

LT

HT

LT

High Tide Source: Pilkey, O. H., and Dixon, K. L. 1996

(modified) The Corps and the Shore. Washington, D.C.: Island Press.Low Tide

B. After seawall

C. Several decades (or more) later

Figure 4.B Seawalls and ecology Idealized diagram showing the effect of seawalls on a sandy beach environment over a period of decades. As the beach slowly narrows, the biodiversity is reducedfor beach animals, including shore birds. In addition, narrower beaches also have less organic debris,including driftwood, that provides habitat for organisms living on the beach.



Ecological Restoration 121

much shorter and of interest to people on Earth today. He stated that modernhuman beings are only one of millions of species that have been on Earth and thateach species is unique and has its own value. Gould argues that there is an appro-priate environmental ethic based upon the issue of the human time scale versusthe “majesty but irrelevance” of geologic time.

Gould’s basic conclusion is that we need to make a “pact” with Earth (ourhome) because She holds all the important playing cards and as such has a power

over us. We are in great need of developing a more compatible relationship withour planet on our time. Earth does not need an agreement with us. Such an agree-ment would be a gift from Mother Earth to us, and is a variation of the golden rule:Do unto others as you would have them do unto you. Gould argues that weshould cut a deal while Earth is still able to enter into such an agreement on ourtime scale. He states, “If we scratch her, she will bleed, kick us out, bandage up,and go about her own business at her own time scale.”5 In other words, if wecontinue to treat our planet with disrespect, we will eventually degrade the envi-ronment for humans and many other living things. As a result, we might becomeextinct sooner, along with many other species. If we sustain ecosystems andresources, we might avoid extinction a bit longer. From a deep time perspective,over hundreds of millions to billions of years, our species will have little effect on

Earth’s history. However, on a time scale of interest to us we would like to hangaround as long as possible. We are not talking about saving Earth. Earth will goon at least a few billion more years with or without us! We are talking aboutsustaining Earth systems that we depend upon for our health and well-being.

What Can We Do to Reduce the HumanFootprint on the Environment?The human footprint on the environment is the impact we have on our planet,including its resources and ecosystems. Just recognizing that the human footprintis growing is a step (poor pun) in the right direction. We recognize that our totalfootprint is the product of the footprint per person times the total number of persons. In order to reduce this impact we need to either reduce the number of

people or reduce the impact per person. The ways most often mentioned are toreduce human population, use resources more efficiently, and learn to manage ourwaste better. It is also important to gain a better scientific understanding of ecosystems. We need to know more about how ecosystems are linked to human-induced change and how our social-cultural environment is linked to thosechanges. When we do this, we recognize the importance of human-dominatedecosystems and their linkages to the broader world. Finally, recognizing that wehave a significant footprint, we have a moral responsibility to manage ecosystems

better. If we wish to maintain biological diversity of “wild ecosystems” with their“wild species,” then we will have to make conscious decisions about how wemanage the environment. Particularly important will be more active management,

because we recognize that the human population increase is unprecedented in

Earth’s history. Never before has one species so clearly dominated the world. Insome cases, changes are increasing and accelerating, and the more we know aboutthese the better prepared we will be for active management of our planet.6

4.3 Ecological Restoration

Restoration ecology is the science behind the process of ecological restoration. Ourdiscussion focuses on the application of the science (restoration ecology) torestoration projects. A simple definition of ecological restoration is that it is theprocess of altering a site or area with the objective of reestablishing indigenous,historical ecosystems. There are many potential restoration projects, includingriver restoration for fish and other wildlife habitat; dam removal to reunite frag-

mented river ecosystems (see A Closer Look: Restoration of the Kissimmee River);



A CLOSER LOOK Restoration of the Kissimmee River

Restoration of the Kissimmee River in central and southernFlorida is the most ambitious river restoration project in theUnited States. Prior to channelization, the river was approxi-mately 160 km (100 mi) long, meandering through a floodplain that was several kilometers wide (Figure 4.C). The riverhad an unusual hydrology because it inundated its floodplainfor prolonged periods of time. As a result, the floodplain and

river supported a biologically diverse ecosystem consistingof wetland plants, wading birds, waterfowl, fish, and otherwildlife.

Prior to about 1940 fewpeople lived in theKissimmeebasinand the land use was primarily farming and cattle ranching.

However, rapid development and growth occurredfollowing World War II, and in 1947, widespread floodingoccurred as a hurricane moved through the basin. As a result,the state of Florida requested the federal government todesign a flood-control plan for central and southern Florida.The channelization of the Kissimmee River was plannedfrom about 1954 to 1960, and between 1962 and 1971 the river

was channelized. Approximately two-thirds of the floodplainwas drained and a canal was excavated, turning the meander-ing river into a straight canal.As a result of the channelization,ecosystem function was degraded. Wetlands with populationsof birds and fish were drastically reduced. Outrage over the

Figure 4.C Restoration of

the Kissimmee River (a) TheKissimmee River in centraland southern Florida prior tochannelization. (South Florida Water

Management District ) (b) TheKissimmee following restoration

which straightened the channel,essentially producing a river as aditch. (South Florida Water

Management District)

(a)

(b)



LAKE KISSIMMEE

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Figure 4.D Kissimmee Riverrestoration plan General plan forrestoration of the Kissimmee River. Oneof the major objectives is to restore bio-logical diversity in ecosystem function of the river as well as re-create the historicriver floodplain environment that isconnected to the main river. (South

Florida Water Management District)

loss of the river went on years before the current restorationeffortswere discussed andplanned.Thepurposeof the restora-tion is to return a portion of the river to its historic meanderingriverbed and widefloodplain. Specificobjectives9 are

Restorehistoricbiologicaldiversity andecosystem function.

Re-create the historicpattern of wetland plant communities.

Reestablish the historic hydrologic conditions with pro-longed flooding of the floodplain.

Re-create the historic river floodplain environment and itsconnection to the main river.

The restoration project was authorized by the U.S. Congressin 1992 in partnership with the South Florida Water Manage-ment District and the U.S. Army Corps of Engineers. Thegeneral plan for the restoration is shown in Figure 4.D.

The restoration of the Kissimmee River is an ongoingproject that began several years ago. By 2001, approximately

12 km of the nearly straight channel have been restored to ameandering channel with floodplain wetlands about 24 kmlong. This returned the ecosystems to a more natural stateas water again flowed through a meandering channel andonto the floodplain. As a result, wetland vegetation wasreestablished and birds and other wildlife are returning. Thepotential flood hazard is being addressed as the restoration

plans allow the river to meander through its floodplain whilemaintaining flood protection. Retaining flood protection isthe reason the entire river will not be returned to what it wasprior to channelization; that is, some of the structures thatcontrol the floodwaters will be removed and others will bemaintained.

The cost of the restoration for the Kissimmee River will beseveral times greater than it was to channelize it. However,the project reflects our values in maintaining biological diver-sity and providing for recreational activities in a more naturalenvironment.




floodplain restoration to improve ecological function; wetland restoration of fresh or saltwater marshes for a variety of purposes from flood control to improvingwildlife habitat to providing a buffer to coastal erosion (see A Closer Look: Restora-tion of the Florida Everglades); beach and coastal sand dune restoration to helpmanage beach erosion and provide wildlife habitat (see A Closer Look: CoastalSand Dune Restoration at Pocket Beaches: University of California, Santa Barbara);restoration of habitat for endangered species; reshaping the land, drainage, andvegetation following surface mining; and restoring habitat for native species andwildlife impacted by clearcut logging or for improved fire management.

A CLOSER LOOK Restoration of the Florida Everglades

The Florida Everglades is considered to be one of the nation’smost valuable ecological treasures. The Everglades’ eco-system stretches from a series of small lakes near Orlando,Florida, southward to Florida Bay for a length of severalhundred kilometers (Figure 4.E). That portion of the eco-system north of Lake Okeechobee comprises the drainagearea feeding into the lake, while the area south of the lakeis a long system of wetlands that may be hydrologicallydescribed as a shallow, wide body of slowly moving water.Tourists from around the world have visited the Evergladesfor generations. They come to see the unique landscape aswell as the wildlife. The Everglades is home to more than11,000 species of plants, as well as several hundred birdspecies and numerous species of fish and marine mammalsincluding the endangered Florida manatee. The wetlandsand surrounding areas are the last remaining habitat fornearly 70 threatened or endangered species, including the

Florida panther and the American crocodile. Since about1900, much of the Everglades has been drained for agricultureand urban developments, and only 50 percent of the originalwetlands remain. A complex system of canals and leveescontrols much of the flow of water for a variety of purposes,including flood control, water supply, and land drainage.

Over many decades the draining of the wetlands and theencroachment of urban areas have degraded the Everglades’ecosystem to the point where the resource was likely to belost without a restoration program. That restoration is nowunderway and it is the largest environmental project in awetland in the world. The program is a 30-year endeavorthat will cost upwards of $10 billion. Restoration goals10

include

Restoration of more natural hydrologic processes.

Enhancement and recovery of native and particularlyendangered species.

Improvement of water quality, especially control of nutrients from agricultural and urban areas.

Restoration of habitat for all wildlife that uses theEverglades.

The restoration plan is an aggressive one that involvesfederal, state, and tribal partners as well as numerous othergroups interested in the Everglades. The progress to date is

notable, as pollution of water flowing into the Evergladesfrom agricultural activities has been reduced by about one-half. As a result, the water entering the system is cleaner thanit has been for years. In addition, thousands of hectares have

been treated to remove invasive, exotic species such asBrazilian pepper trees and tilapia (a fish from Africa) with theobjective of improving and conserving habitat for a variety of endangered and other species.

The plan to restore the Everglades is a long-term oneand involves many years of scientific research yet to becompleted. The program is complicated by the fact that over5 million people live in south Florida. The area has a rapidlygrowing economy, and many urban issues related to waterquality and land use need to be addressed. Perhaps the biggest issue is the water and the plan will need to carefullyconsider restoration that delivers the water in the properamount, quantity, and place to support ecosystems in the

Everglades. This will be a challenge because millions of people in South Florida are also competing for the water.

The overriding goal of the restoration is to ensure the long-term sustainability of water resources in the Everglades’ecosystem.10 Doing this includes

Controlling human population in south Florida, access tothe Everglades by people, and human development thatencroaches on the Everglades.

Applying the principle of environmental unity (seeChapter 1; everything affects everything else) to betterunderstand and anticipate possible consequencesresulting from changes to the geologic, hydrologic, andecological parts of the system.

Applying the precautionary principle (see Chapter 1).

Analyzing rates and changes of systems related to thewater, land, and wildlife as linked to people.

It is clear that the people of south Florida and the nation valuethe Everglades’ ecosystem and are applying science withvalues to implement a far-reaching ecological restorationprogram. Hopefully it will be successful and future genera-tions will look back to this point in time as a “watershed”(poor pun) that started the ball rolling to protect one of themost valuable ecological resources in North America.




GEORGIAALABAMA

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Figure 4.E Florida Everglades (a) Map of Florida showing theEverglades in southernmost Florida. The Everglades is a wide, shallow,flowing riverlike system extending from Lake Okeechobee south to the Atlantic Ocean. (b) The Florida Everglades is a diverse ecosystem.(Farrell Grehan/CORBIS )

A common objective of the restoration process is to change a degraded eco-system so that it resembles a less human-disturbed ecosystem and contains thestructure, function, diversity, and processes of the desired ecosystem. In an attemptto add a human and social component to ecological restoration, it might also bedefined as the process of deliberately modifying a site or area to compensate forenvironmental degradation caused by humans. The purpose of the restoration isto reestablish sustainable ecosystems and develop a new relationship betweenthe natural environment and the human-modified environment.7 When we tryto apply these ideas and principles, we come to the realization that many

(a)

(b)




human-altered environments are nothing like natural systems. Furthermore, it isnearly impossible to restore many sites to their initial conditions because they have

been irreversibly changed. For example, many coastal wetlands and river wetlandshave been drained, filled in,and developed forhuman use. Returningthem to theiroriginal condition would be impossible. Therefore, a more practical approach is toattempt to transform the present ecosystems and landscapes into ones that moreclosely resemble ecosystems less disturbed by human processes. For example,

planning to restore a river that flows through a city might to include removal of nonnative species, replanting native plants, and allowing the river to behave in amore natural state within its floodplain. In doing so, the restoration would producea greenbelt along a river that is well vegetated and contains portions of ecosys-tems that were present prior to urbanization. The result would be a compromise

between ecological restoration to establish what was there prior to urbanizationand the production of a more natural river system that functions more like riversfound in a nonurban environment.8

It is possible to restore a variety of landscapes, but regardless of what is beingrestored, consideration must be given to several major factors that we sometimescall the “Big Three” in restoration. These are hydrologic process, soil and rock, andvegetation. Hydrologic process includes the entire hydrologic cycle, referring to

surface waters and groundwater. Soils and rocks include the microorganisms thatreside in the soil. Vegetation is the cover material on land and in wetland ecosys-tems. When we apply the Big Three in a restoration project we soon realize thatecological restoration, as it is applied today, is part art and part applied science.This results because we do not often know enough about particular ecosystems todefine their function, structure, and process accurately. Ecological restoration alsohas a component of societal contribution that goes along with the scientific contri-

bution. In this respect restoration is a social activity. The contribution from people incommunities where restoration will take place, or as they are sometimes called, thestakeholders, is important in establishing goals for restoration. A series of publicmeetings for comment and recommendations are held prior to starting restorationprojects. There is feedback between the goals and scientific endpoints, which are a

consequence of the goals. Forexample, if we are restoring a salt marsh and want theplants in the marsh to reduce the nutrient loading to a particular level, then thatlevel is a scientific endpoint. If it turns out that the endpoint may not be reached,then further consideration of goals may be in order. The scientific measures refer tothe measurements and monitoring that happen along the way toward achievementof scientific endpoints andthegoals of therestoration.Thecontributionof science isimportant in developing the endpoints and measures.

Ecological restoration may vary from very simple procedures, such as remov-ing exotic species of plants and planting desired species, with a focus on therestoration of composition and structure, to reconstruction of the entire landscapewith a focus on process. Reconstruction of a landscape and its ecosystems requiresintimate knowledge of geologic and hydrologic processes. Table 4.1 lists details of the processes of restoration.

Regardless of the nature and extent of the restoration being done, it is anegotiated process between people interested in the project, those doing therestoration, and scientists making recommendations, gathering data, and analyz-ing results. It is also important to recognize that evaluation of the restorationproject starts long before construction. This evaluation involves identifying envi-ronmentally sensitive aspects of the project and how they might interact withimportant historic or cultural values. Prior to construction a careful evaluation of the geologic, hydrologic, and vegetation conditions at the site is necessary tomatch the environment to the restoration procedures. In other words, we evalu-ate the hydrology, geology, and vegetation in terms of the overall goals of theproject and what is being restored. During restoration, monitoring is often neces-sary to help evaluate whether the objectives are being achieved. Also, during the

entire project, including the development of goals, those doing the restoration



A CLOSER LOOK

Coastal Sand Dune Restoration at PocketBeaches: University of California,Santa Barbara

The University of California, Santa Barbara, has severalkilometers of beach on its campus. Two small pocket beachesexist at locations where the sea cliff is interrupted or cutthrough by prehistoric channels. At these locations somesand blows from the beaches inland for several tens of meters and a series of low coastal sand dunes have devel-oped. Over the years, the dunes were colonized by a SouthAfrican species of ice plant. The ice plant came to cover theentire dune, inhibiting normal dune function by allowing noother plants to grow and inhibiting natural sand movement.As a result, the biodiversity of the dune ecosystem wasgreatly reduced. Restoration of the dunes has involved

solarizing the ice plant. This is done by covering the plants

with black plastic for several months until they die and turninto mulch. The dune is then planted with native dunespecies (Figure 4.F). As native vegetation returns to thedunes, the ecosystem is restored. The restoration of the duneswas simple and straightforward, with limited objectives of removing exotic, invasive species and replacing them withnative species. When this was done the function of theecosystem recovered and biological diversity increased. Inthis case the restoration of composition (plants) promotesthe restoration of process (allows the sand in the dunes tomove). However, in the Everglades and Kissimmee Riverexamples hydrologic processes need to be restored prior to

restoring composition.


should work closely with the community people involved, including environmentalists,property owners, and other interest groups, to maximize opportunities to cooperate in therestoration project. Finally, it’s important to recognize that ecological restoration, whileoften successful, is likely to have mixed success. This is particularly likely in the first yearsof a restoration project, when unexpected difficulties often occur, making changes in therestoration plan necessary. There may also be natural events such as droughts or severestorms that will interfere with the restoration activities.

Another concept related to ecological restoration is biological engineering, which is the

use of vegetation in engineering projects to achieve specific goals such as protecting stream banks from erosion.7,8 On a broader scale, ecological engineering includes designing andconstructing ecosystems.

TABLE 4.1 Steps and Procedures in Planning and Initiating an Ecological

Restoration Project

1. Develop an ecological description of the area to be restored.

2. Provide a clear understanding of the need for the restoration.

3. Define the objectives and goals of the project.

4. Specifically state the procedures that will be used to achieve the restoration.

5. Clearly know the reference ecosystem that the restoration is attempting to reach.

6. Determine how the restored ecosystem will be self-sustaining; that is, provide for flow of energy and

cycling of chemicals to ensure long-term self-maintenance of the restored ecosystem and stable

linkages to other ecosystems.

7. State the standards of performance during restoration and monitoring following completion.

8. Work with all people (stakeholders) interested in the project from initiation through completion and

postproject monitoring.

9. Examine what the potential consequences of the project are likely to be; that is, apply the principle of

environmental unity, that everything affects everything else and anticipate what primary, secondary,

and tertiary effects may be.

Source: Modified after Society for Ecological Restoration, 2004. The SER international primer on ecological

restoration, www.SER.org.



SUMMARY

Ecology is the study of living things and their interactionsand linkages to each other and their nonliving environment.It can also be viewed as the study of factors influencing thedistribution and abundance of species. An ecosystem is acommunity of organisms and their interactions with thenonliving environment in which energy flows and chemicals

cycle. Therefore, an understanding of ecosystems involves

understanding the geologic, biogeochemical, and hydrologicenvironment.

Geology has many linkages to biodiversity through itsinfluence on the abundance and distribution of plantsand animals. Examples include trout habitat in southernCalifornia; the forests of North America and Europe; wolves

and elk in Yellowstone National Park and their relationship

Figure 4.F Sand dune restoration Sand dunes at the University of California, Santa Barbara,following restoration.The invasive species has been removed and native dunes species have been planted.(Edward A. Keller)




Revisiting Fundamental Concepts

Human Population Growth

Controlling human population growth is an important objec-

tive in sustaining our environment and reducing the humanfootprint on the environment. If we are unable to controlhuman growth, we will have little success in achievingsustainable management of our resources.

Sustainability

Sustainability is the environmental objective. SustainingEarth’s ecosystems is necessary if we hope to sustain ourhuman system. We share our planet with a vast number of other living things and many of these are necessary for ourown well-being. Therefore, when we consider geology andecosystems, we need to consider those linkages that will leadto sustainable development in its broadest context.

Earth as a System

Ecosystems are an important component of Earth systemsthat link living organisms with their nonliving environment.Geologic and hydrologic systems have simple to complex

relationships withcommunities oforganisms.These organismshave important linkages to the diversity of living organisms inecosystems. Maintaining living systems in a desired and sus-tainable state must involve understanding the role of geologicand hydrologicprocesses and maintaining these processes in away thatsupports the desiredbiological conditions.

Hazardous Earth Processes, Risk Assessment, and Perception

Ecosystems have natural service functions that are linked tohazards such as landslides and flooding. Bank vegetation onstream banks increases the stability of stream banks and theirresistance to erosion. Wetlands moderate floodwater bystoring and releasing it slowly, thus reducing flood hazards.Wetlands provide a buffer to storm waves from the ocean andthus help protect coastal areas from erosion and flooding.

Scientific Knowledge and ValuesThe science of ecology has provided a lot of informationabout ecosystems. How we use that knowledge to restore andmaintain ecosystems will reflect our values.

Key Terms

ecology (p. 106)

ecosystem (p. 108)

biodiversity (p. 109)

ecological restoration (p. 121)

1. Define an ecosystem.

2. What is the relationship between a species and ecologicalcommunity?

3. What is meant by biodiversity?

4. What factors may increase or decrease biodiversity?

5. What was learned by the case histories of wolves inYellowstone National Park and sea otters in the kelp

forest of southern California?

6. How do seawalls reduce biodiversity?

7. What is meant by the golden rule of the environment?

8. What is ecological restoration?

9. What is the difference between ecological restoration,naturalization, and biological engineering?

10. What are some important linkages between geologyand ecology?

Review Questions

Review Questions 129

to stream processes; and the kelp forest in California relatedto the interaction of sea otters and the urchins they eat.

Human activity and interest dominate almost all eco-systems on Earth. Our processes (influences) are reducing biodiversity, including the loss of entire ecosystems and theextinction of many species. The processes of most concern areland transformation, as, for example, transformation of the

land from a natural environment to agriculture or urban uses;introduction of invasive species; processes that cause globalchange; and change to biogeochemical cycles. Reducing thehuman footprint on the ecosystems of Earth is an importantobjective and will include, among other activities, controlling

human population, managing Earth’s resources for sustain-ability, and managing our waste more efficiently.

We are in need of an appropriate environmental ethic based on a time scale of interest to people. If we choose tosustain resources and ecosystems, we will have a morecompatible relationship with our home (Earth) and ourspecies will be able to remain on the planet a bit longer.

Ecological restoration is emerging as an important processwith a variety of goals and objectives. In general, ecologicalrestoration has the purpose of reestablishing sustainableecosystem structure, process, and function.




Critical Thinking Questions

1. An ecosystem consists of an ecological community aswell as its nonliving environment. Which of the two doyou think is more important and why? In other words,do you think the physical environment comes beforewhat lives there or does what lives there affect the

physical environment to a greater extent than the roleof geology? Or are both things equally important?

2. Visit a local stream. Carefully examine the stream andsurrounding environment and try to determine theamount of human domination. Is the stream you are

looking at a candidate for restoration? If so, what could be done? If not, why not?

3. Why may some geologists and hydrologists not beparticularly aware of ecosystem function in terms of the

biological environment and why are some biologistsunaware of the details of the physical and hydrologicalconditions of the ecosystems they work with? What can be done to narrow the gap between those working onliving systems and those working on geological orhydrological systems?

Documents

ch04 Ecology and Geology