Garden Ecology

Study Guide

Garden EcologyBy

Matt Brooks

About the Authors

Matt Brooks received a Bachelor of Landscape Architecture degree

from the University of Illinois and a Master of Landscape Architecture

degree from the University of Minnesota. He then spent several

years working in the Chicago area with various landscape architec-

tural and design/building firms. In these positions, Matts primary

responsibilities included landscape design and sales and project

management of commercial-, institutional-, and residential-scale

projects. Soon after moving to Minnesota in 1997, Matt accepted a

teaching position with Dakota County Technical College, where he

teaches courses in landscape design, computer-aided design (CAD),

and woody plant identification. In addition to teaching, Matt is

president of Brooks Design Group Inc., a landscape design and

construction services consulting company. Matts work has appeared

in Better Homes and Gardens, in Northern Gardener, and most

recently at the University of Minnesota Landscape Arboretum. Matt

is a member of the Minnesota Nursery and Landscape Association,

where he sits on the Environmental Concerns Committee. He is

also a member of the American Society of Landscape Architects.

Copyright 2012 by Penn Foster, Inc.

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Requests for permission to make copies of any part of the work should be mailed to Copyright Permissions, Penn Foster, 925 Oak Street, Scranton,Pennsylvania 18515.

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03/13/2014

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INSTRUCTIONS TO STUDENTS 1

LESSON ASSIGNMENTS 7

LESSON 1: THE FUNDAMENTALS OF PLANT

AND SOIL SCIENCE 9

LESSON 2: GARDEN ECOLOGY 27

LESSON 3: THE FUNDAMENTALS OF

COMMON-SENSE PEST CONTROL 49

SELF-CHECK ANSWERS 73

ACHIEVEMENT REVIEW ANSWERS 80

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INTRODUCTION

Landscaping can be defined as the art and science of altering

the visible features of the land, which results in the creation

of beautiful and functional outdoor environments. Alterations

through the incorporation of living elements such as trees,

shrubs, and flowers; natural elements including landforms,

stones, or water; and built elements such as garden struc-

tures, walls, and fences rely on the artistic eye. On the other

hand, an understanding of the environment, the natural

processes that occur in shaping it, and the intricate relation-

ships that exist among the living organisms that dwell there

form the scientific basis of landscaping. Ecology is the term

used to describe the scientific study of the relationships that

occur between living organisms and between living organisms

and their environment. This course presents the concepts of

garden ecology and examines both the living and nonliving

natural components that form the framework of gardens and

the larger landscape.

This course includes three lessons. Heres a summary of

what youll study in each one:

In Lesson 1, The Fundamentals of Plant and Soil

Science, youll gain a basic understanding of plants and

soils. Youll learn about plant structure, the function of

various plant parts, and the growth processes inherent

in green plants. Youll also be introduced to the methods

and terms used in identifying plants, the scientific system

for naming plants, the reproductive process in plants,

and the role plant regulators play in the production of

plants. Last, youll study the vital role soils play in the

health of plants, the way soils are formed, differences in

soil structure, and the chemical properties of soils.

Lesson 2, Garden Ecology, builds upon the fundamental

information learned in Lesson 1 through a more holistic

approach that introduces you to the science of ecology as

it applies to the smaller-scale garden or residential land-

scape. While some of the information in this lesson will

be familiar to you from your readings in Lesson 1, this

additional perspective on the fundamentals will prove

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quite beneficial in a deeper understanding of the subject

matter. In this lesson, youll learn to appreciate not only

the individual parts that make up the garden or land-

scape but also the intricate interactions among the

various parts that make it a highly functioning ecosystem.

In Lesson 3, The Fundamentals of Common Sense Pest

Control, youll learn about the various natural controls

that keep pest populations in check. Youll also be intro-

duced to the concept of integrated pest management (IPM)

and the treatment strategies and tactics utilized in man-

aging pests in the garden and landscape. Youll learn

how to identify and appreciate the services of beneficial

insects and other organisms in controlling pest popula-

tions. Next you'll learn how to choose the right chemical

and microbial tools as well as other organic and inor-

ganic tools used in common sense pest control. And

lastly, this lesson will introduce you to the new frontier

of microbials, pheromones, and insect growth regulators

used in pest control today.

These three lessons are further divided into several individual

assignments that typically correspond to one, sometimes two,

chapters in one of your textbooks. At the end of each assign-

ment, youll complete a self-check to determine how well

youve learned the material youve just studied. The answers to

the self-checks are at the back of this study guide. At the

end of each lesson, you must complete an examination.

OBJECTIVES

When you complete this course, youll be able to

Describe the relationships among landscapes, plants,

and the soils and other living organisms that make up

the ecology of our gardens

List the important roles plants play in our lives and

Earths ecosystem

List the parts typical of higher green plants and explain

their functions

Instructions to Students2

Describe the process of photosynthesis and the role it

plays in sustaining all life on Earth

Summarize the natural classification system for the

plant kingdom

Describe the environmental factors that affect plant

growth

Identify the parts of plants that are used in plant

identification

Explain the important role soils play in our lives and

Earths ecosystem

Describe the various components that make up soils and

explain how and why soils differ

Define the term soil structure and list the factors that

influence various soil structures

Describe the different types of plant growth regulators

and their effects on plants

Explain the various forms of plant reproduction and list

the parts of a plant involved in the process

Identify the most common methods used in plant

propagation

Identify the major causes of injury to plants

Identify natural pest controls

List the principles of common sense pest control

Explain the concept of integrated pest management (IPM)

List the different types of beneficial insects and organ-

isms used in IPM

Describe the various organic and inorganic tools used

in IPM

Instructions to Students 3

COURSE MATERIALS

This course includes the following materials:

1. This study guide, which contains an introduction to your

course, plus

A lesson assignments page with a schedule of study

assignments

Introductions to lessons and assignments, which

emphasize the main points in the textbooks

Self-checks and answers to help you assess your

understanding of the material

Answers to the Achievement Review features at the

end of each chapter in Ornamental Horticulture

2. Your course textbooks, Ornamental Horticulture: Science,

Operations, & Management; Ecology for Gardeners; and

The Gardeners Guide to Common-Sense Pest Control,

which contain the assigned reading materials

YOUR TEXTBOOKS

This course includes three textbooks: Ornamental

Horticulture: Science, Operations, & Management; Ecology for

Gardeners; and The Gardeners Guide to Common-Sense Pest

Control. These books contain the study material on which the

self-checks and examinations are based. You should become

familiar with your textbooks prior to the beginning of your

studies. Skim through the contents pages of each book. These

pages will give you a preview of the chapters in each text-

book, as well as a listing of topics specific to each chapter.

Note: Only selected chapters in your textbooks are required

reading for this course.

Each chapter in Ornamental Horticulture begins with a list

of objectives and key terms. Read these objectives prior to

beginning your studies, as theyll prepare you for what youll

be learning. While reading, pay particular attention to the key

terms that are highlighted in bold type throughout the


chapters. At the end of each chapter is a feature called

Achievement Review. You can use these questions to review

what youve just read and studied in a chapter. The answers

to these exercises are at the back of this study guide. Starting

on page 627 are a number of appendices, which contain use-

ful information such as professional trade organizations,

selected readings for further studies in ornamental horticul-

ture, and examples of plant diseases and insect injuries. A

glossary of all of the key terms listed in your book begins on

page 649. You may find this glossary useful when reviewing

for exams. Finally, an index begins on page 661. Use this

feature to locate specific topics in the textbook.

Your second textbook, Ecology for Gardeners, is broken down

into six chapters. It too contains a glossary of terms that

begins on page 280, a list of books for further reading on

pages 290291, an index of common and scientific names

starting on page 292, and a subject index starting on page

320. In the middle of the textbook (between pages 96 and 97)

are numbered photo plates, which are referenced throughout

the book. The vast amount of information presented in this

book may at times overwhelm you with all of the scientific

names and terminology, and thats OK. Heres a suggestion to

help in your studying: First read through each chapter to get

an overall idea of the material presented, and then go back

with a highlighter and mark the major terms and concepts in

preparation for your exam reviews.

Your third textbook, The Gardeners Guide to Common-Sense

Pest Control, is broken down into two parts. For this study

guide youll be assigned readings from the first half of the

book and in a later study guide youll be referencing the sec-

ond half of the book. In addition to the assigned readings, you

should read the Preface and Introduction and pages 1316

on sustainable landscape gardening. While not included as

part of your assigned readings, these pages contain insightful

information from the authors and set the tone for the content

presented in the rest of the book. Starting on page 374 is the

Afterword with some closing thoughts by the author followed

by a sample case study that uses the city of San Francisco's

IPM program as an example to highlight the application of the

principles and practices presented in this book. Starting on

page 378 is a reference section with suggestions for further

Instructions to Students 5

Note: When referencingthis textbook in yourassignments the titlewill be abbreviated toPest Control.

reading on particular subjects, listed according to book chap-

ter. Lastly, starting on page 383 is the index, which youll find

helpful when looking up information on a particular topic.

A STUDY PLAN

The following is a recommended procedure for successfully

completing this course while receiving the maximum benefit

from your studies:

1. Read the introduction to each assignment and make

note of assigned readings in both the study guide and

textbook.

2. When applicable, read the chapter objectives at the

beginning of assigned textbook readings; then read the

material for a general understanding of subject matter.

3. Go back and reread assigned materials, highlighting or

underlining key concepts and passages to help you

remember essential information.

4. When you feel you have an understanding of the assigned

reading, take the self-check at the end of the assignment

in your study guide. Compare your answers with those

given at the end of this guide. If you had any incorrect

answers, go back and review the assigned reading mate-

rial. This review will reinforce your understanding of the

material. The self-checks are designed to reveal weak

points that you need to review. Dont send the self-check

answers to the school. Theyre for you to evaluate your

understanding of the material.

5. Complete each assignment in this way.

6. When you feel you understand all of the material in a

lesson, complete the examination for that lesson.

7. Repeat this procedure for each lesson.

Remember: At any time, you can email your instructor for

information regarding the materials. The instructor can pro-

vide you with answers to any questions you may have about

the course or your study materials.

Youre now ready to begin Lesson 1. Good luck!


Lesson 1: Fundamentals of Plant and Soil Science

For: Read in the Read in the textbook

study guide: Ornamental Horticulture:

Assignment 1 Pages 1011 Chapter 1





Examination 102835 Material in Lesson 1

Lesson 2: Garden Ecology

For: Read in the Read in the textbook

study guide: Ecology for Gardeners:

Assignment 6 Page 29 Chapter 1







7

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Lesson 3: Fundamentals of Common Sense Pest Management

For: Read in the Read in

study guide: the textbook:

Assignment 12 Pages 5052 Chapter 6 in Ornamental

Horticulture

Assignment 13 Pages 5456 Chapter 2 in Pest Control

Assignment 14 Pages 5759 Chapters 34 in Pest

Control


Assignment 16 Pages 6466 Chapters 67 in Pest

Control



Lesson Assignments8

Note: To access and complete any of the examinations for this studyguide, click on the appropriate Take Exam icon on your My Coursespage. You should not have to enter the examination numbers. Thesenumbers are for reference only if you have reason to contact StudentServices.

Remember to regularlycheck My Courseson your studenthomepage. Yourinstructor may postadditional resourcesthat you can accessto enhance yourlearning experience.

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Fundamentals of Plant and Soil ScienceThe purpose of Lesson 1 is to provide you with a basic under-

standing of plants and the soils they depend upon for growth

and reproduction. This lesson includes five assignments that

cover Chapters 15 in the textbook Ornamental Horticulture.

Assignment 1 covers plant morphology (structure), plant

nomenclature, plant processes, and requirements for plant

growth. Assignment 2 focuses on the terminology and meth-

ods used in describing and identifying plants. Assignment 3

discusses the properties of soil and its importance in plant

health. Assignment 4 explains how and why growth regula-

tors are used, and finally, Assignment 5 describes the many

ways in which plants naturally reproduce and the methods

used by humans in propagating plants.

OBJECTIVES

When you complete this lesson, youll be able to

Summarize the important roles plants play in peoples

lives and in Earths ecosystem

List the parts typical of higher green plants and the

functions of these parts

Describe the process of photosynthesis and the role it

plays in sustaining all life on Earth

Describe the natural classification system for the plant

kingdom

Describe the environmental factors that can affect plant

growth

Identify the parts of plants that are used in plant

identification

Explain the important role soils play in peoples lives and

in Earths ecosystem

Characterize the various components that make up soils

and indicate how and why soils differ

Garden Ecology10

Define the term soil structure and list the factors that

influence various soil structures

Identify the different types of plant growth regulators and

describe their effects on plants

Explain the various forms of plant reproduction and

identify the parts of a plant involved in the process

Describe the most common methods used in plant

propagation

ASSIGNMENT 1: THE GREEN PLANT

Read the following material. Then read Chapter 1 (pages 124)

in your textbook, Ornamental Horticulture.

Green plants are amazing machinesthe only organisms

capable of manufacturing their own food. Through a process

known as photosynthesis, plants use the raw materials of

sunlight, soil, air, and water to produce the food they need.

In addition, plants are the source of some important nutri-

tional needs of humans. For example, the leaves of some

plants, such as spinach and kale, are loaded with vitamins

and minerals, while tea leaves are brewed into a beverage

rich in antioxidants that protect the human body from ill

health. Other plant partssuch as the roots of carrot and

potato plants; the fleshy fruits of apple and orange trees;

nuts from trees and shrubs; and most notably, the grains

produced by corn, rice, and wheatare sources of nutrition.

Textbook Note

On page 16 of your textbook, the chemical equation for photo -synthesis should read as follows:

6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O

The equation in the textbook is missing the C immediately after the yield symbol.

Lesson 1 11

Even the ground beef in your hamburger and the eggs in

your omelet depend on plants as the nutritional source for

the cow and chicken that produce the meat and eggs.

Plants also provide raw materials used in the manufacture

of products that bring comfort to peoples lives. For example,

plants are sources for the building materials used in the con-

struction of homes that shelter people from the elements;

theyre the basis of some fibers used in making clothing that

keeps people warm and dry. Other uses for the woody parts

of a plant include the manufacture of paper products that

allow people to communicate the written word through books

and newspapers, to package and ship goods across the

country, and to have a hot pizza delivered to their front

doors. And how would the pizza get delivered if not for the

fossil fuels made possible by plants that covered Earth mil-

lions of years ago?

As a student in the Landscape Technology program, youll

learn to appreciate plants in another way as wellthat is,

for their aesthetic and functional roles in gardens and land-

scapes. To effectively use plants in creating beautiful and

functional outdoor spaces, you must have a basic under-

standing of plants. The purpose of this assignment is to help

you gain that understanding by introducing you to plant

structure, the terminology used in describing the parts of a

plant, the process of plant growth, and the requirements for

proper growth. Youll also be introduced to the system of

classifying and naming plants.

Now its time to complete Self-Check 1 to help you review

what youve just studied and determine how well you under-

stood the material. In addition, you may wish to complete the

Achievement Review on pages 2427 of the textbook. The

answers to this review can be found at the back of this study

guide.

Garden Ecology12

Self-Check 1

At the end of each section of Garden Ecology, youll be asked to pause and check

your understanding of what youve just read by completing a Self-Check exercise.

Answering these questions will help you review what youve studied so far. Please

complete Self-Check 1 now.

Note: You may also wish to use the reviews at the end of the chapters in your textbook.

The answers to these reviews are also found at the end of this study guide.

Match each term in the left column below with its definition in the right column.

______ 1. Photosynthesis

______ 2. Chlorophyll

______ 3. Oxygen

______ 4. Flower

______ 5. Transpiration

______ 6. Taxonomy

______ 7. Plant nomenclature

______ 8. Latin

______ 9. Phototropism

______ 10. Cell walls

Check your answers with those on page 73.

a. The language used in the scientific/botanical naming of plants

b. A gaseous byproduct of photosynthesis required forhuman survival

c. The structures present in plant cells that make themdifferent from animal cells

d. The process of converting energy from solar to chemi-cal form through the manufacture of sugar

e. The scientific study of plant classification

f. The green pigment needed by plants to capture thesuns energy

g. The process through which water vapor is releasedthrough pore-like openings in the leaf

h. The system for naming plants

i. The plant structure containing both pistil and stamen

j. The term used to describe a plants bending growth inresponse to a light source

Lesson 1 13

ASSIGNMENT 2: DESCRIBINGAND IDENTIFYING PLANTS

Read the following material. Then read Chapter 2, pages 2844,


Plants are the primary materials that landscape professionals

use to create attractive gardens and landscapes. The key to

successfully using plants in landscapes is the ability to

describe and identify plants. The problem is that there are

many different methods of describing plants.

One method uses plants common names. This method is

complicated by the fact that one plant may go by several

different names. For example, many people use the term

burning bush to describe a particular shrub that turns

bright red in autumn. Others, however, refer to this

same bush as the winged euonymus. You can see how

using plants common names may lead to confusion.

Another method uses the scientific names of plants that

you learned about in Chapter 1. This method was devel-

oped by Karl von Linne, the father of taxonomy. In this

system, each plant has its own unique scientific name

that consists of two parts, the genus and species.

Although this system eliminates confusion among

scientists and professionals familiar with this language,

confusion persists among the general population, who

usually refer to plants by their common names.

As a landscape professional, you should be knowledgeable in

both the scientific and common names of plants. While over-

whelming at first, continued practice and learning through

repeated use will result in the mastering of this new language

that separates landscape professionals from hobbyists.

In addition to their scientific and common names, plants may

also be identified or named in other ways. Here are a few dis-

cussed by your textbook in Chapter 2:

Horticultural descriptions of plants. Because the botanical

classification and scientific naming of plants is very spe-

cific, it reduces confusion. However, a less complicated

method with more generic terms is often used to refer to

Because a scientificname consists of twoparts, its called a binomial.

Garden Ecology14

larger groups of plants that share like physical character-

istics. For example, the term deciduous refers to plants

that shed their leaves annually, while the term evergreen

refers to plants that retain them for several years. Such

broad categories are useful among professionals in the

field of ornamental horticulture. Your textbook lists and

describes these categories of plants in greater detail on

pages 2931.

Description based on temperature tolerance. Plants are

also categorized according to their tolerances of high

and low air temperatures. While water, sunlight, and

soil nutrients are contributing factors in a plants ability

to survive, temperature extremes are of paramount

importance in determining the suitability of a plant

to a particular climatic zone. The term plant hardiness

describes this ability for plant survival based on air tem-

perature. Hardiness zones have been devised to indicate

a plants suitability to different geographic regions of the

globe. Both heat and cold hardiness zones are displayed

on maps that serve as a general guide to proper plant

selection based on this limiting factor. (Page 32 in your

textbook illustrates a hardiness zone map of North

America.) Specific site features, such as a south-facing

wall or the proximity to large bodies of water or to a large

city, can influence air temperatures on a smaller scale.

Although such features may not appear on the hardiness

zone maps, they can have an influence on the selection

of appropriate plants for a specific location.

Visual descriptions of plants. In the final pages of

Chapter 2, youll examine the physical features (leaves,

twigs, and fruit) that aid in plant identification. The abil-

ity to correctly identify plants is a skill vital to landscape

The website for the U.S. Department of Agriculture includes an inter-active hardiness zone map. To locate this map, type departmentagriculture hardiness zone map into your browsers search box.

Lesson 1 15

professionals. To obtain this skill, you must acquire

a basic familiarity with the terms used in plant

identification.

While the vast amount of information presented in your text-

book can be rather intimidating at first, over time these plant

features and the terms used to describe them will become

second nature to you. In the meantime, when an unfamiliar

term appears in the description of a plant, take the time to

look it up in the glossary or index of your book.

Now, take a moment to complete Self-Check 2 and the

Achievement Review on pages 4446 of the textbook to help

you review what youve just studied. Once you understand

the material, move on to Assignment 3.

Garden Ecology16

Self-Check 2


______ 1. Linnaeus

______ 2. Herbaceous

______ 3. Perennial

______ 4. Hardiness

______ 5. Alternate

______ 6. Chambered

______ 7. Raceme

______ 8. Pome

______ 9. Lobed

______ 10. Naked


a. A term used to describe a type of fruit

b. A term used to describe a bud lacking bud scales

c. The father of taxonomy

d. A term used to describe the structure of a flower

e. A plant that doesnt die after flowering; a plant that can survive the cold in a dormant state

f. A term used to describe the margin of a leaf blade

g. A term used to describe the arrangement of leaves along a plant stem or twig

h. The term used to describe a plant lacking a hard bark coveringon its stems

i. A term used to describe the pith or inside of a stem or twig

j. The term used to describe a plants tolerances based on tem-perature extremes

Lesson 1 17

ASSIGNMENT 3: THE SOIL



What Is Soil?

To most people, soil, or dirt, is a nuisance that gets tracked

into the house. To a farmer or horticulturist, however, soil is

the life-giving medium that anchors and nourishes the plants

that are the lifeblood of their professions.

If you want to become a successful landscape professional,

you must have an understanding of the complexities of soil

and its influence on the health of plants. In this assignment,

youll be introduced to physical components that make up

soils and how soils differ. Youll also study the chemical ele-

ments essential to plant growth and the processes through

which these elements become available for use by plants.

The primary components of soil include mineral particles

(weathered rock in the form of gravel, sand, silt, and clay),

organic matter, air, and water. Generally, the ratio of these

elements is as follows:

Mineral particles form the bulk of most soils at roughly

45%.

Organic matter contributes only 5%. Of this 5%, approxi-

mately 80% is in the form of humus, with the remaining

20% equally split between roots and living organisms.

Air and water account for approximately 25% each.

Soil Separates and Soil Texture

The size and proportion of the mineral particles in soil deter-

mine the classification of that soil. These particles are called

soil separates. Since most soils contain a percentage of sand,

silt, and clay, these three separates are used to determine the

classification of soil.

Garden Ecology18

Page 52 in your textbook illustrates the soil texture triangle

developed by the U.S. Department of Agriculture. This triangle

is used to classify the texture class of a soil. If you know the

percentage of two of the three separates (sand, silt, and clay),

you can determine the classification of the texture of a soil.

Heres how it works: The sides of the soil texture triangle are

scaled for the percentages of sand, silt, and clay. Clay per-

centages are read from left to right across the triangle. Silt is

read from the upper right to lower left. And sand is read from

lower right toward the upper left portion of the triangle. The

boundaries of the different soil texture classes are highlighted

in bold dashed lines.

The intersection of the three particle sizes on the triangle

gives the texture class. For instance, suppose you have a soil

with 20% clay, 60% silt, and 20% sand. Heres how to use

the triangle to determine the soil texture.

1. Find 20 along the side for clay, and draw a line from left

to right from the 20.

2. Find 60 along the line for silt, and draw a line from the

60 down and to the left.

3. Find 20 along the line for sand, and draw a line from the

20 up and to the left.

4. Identify the section in which these three lines intersect.

In this case the soil is silty loam.

Note: In this example, we used the percentages for all three

separates. However, if you know only two of the three, you

can still use the triangle. The intersection of the two lines will

give you the type of soil.

Soil Structure and Organic Material

As youve just learned, the main mineral components of soil

are sand, silt, and clay particles. You also learned that

different types of soil contain different amounts of these

components. In addition, the arrangement of soil particles,

called soil structure, influences the makeup of soil. According

to the website for the U.S. Department of Agriculture, soil

structure is the combination or arrangement of primary soil

Lesson 1 19

particles into aggregates [larger particles of soil]. . . Soil

structure affects water and air movement through soil,

greatly influencing soils ability to sustain life and perform

other vital soil functions.

In a nutshell, soil structure, or the arrangement of soil parti-

cles, influences the soils ability to support plant life.

Soil Acidity and Alkalinity

There are 17 elements essential for plant growth, including

carbon, nitrogen, calcium, magnesium, iron, zinc, copper,

and others. Of these 17 elements, soil provides all but three

of them. Only carbon, hydrogen, and oxygen are obtained by

most plants from sources other than the soil. These elements

determine the pH number, which indicates the acidity, alka-

linity, or neutrality of soil. The pH number of a soil affects

the capacity of that particular soil to make essential elements

available for absorption by plant roots. Just as air tempera-

ture extremes can be a limiting factor in making plant

selections, so too can the pH of a soil. That is, certain plants

require a specific pH for optimal growth and even survival.

While its possible to modify the pH of a soil through organic

and/or chemical means, its usually best to select plants

according to existing soil conditions.

Pedology, the study of soils, is a science as complex as

botany, the study of plants, or zoology, the study of animals.

You would need years of study to become an expert in the

field. The purpose of this assignment is to introduce you to

properties of soil and the importance soils play in the health

of plantsnot to make you an expert. Future assignments in

this study guide expand on the knowledge gained here, allow-

ing you the ability to appreciate the vital role soils play in a

healthy landscape.




the material, move on to Assignment 4.

Garden Ecology20

Self-Check 3


______ 1. pH

______ 2. Pedology

______ 3. Humus

______ 4. Clay

______ 5. Soil structure

______ 6. Cation exchange

______ 7. Alluvial soil

______ 8. Air

______ 9. Acidic soil

______ 10. Alkaline soil


a. A chemical reaction necessary for preventing essentialnutrients from being leached from the soil

b. The soil separate with the smallest particles

c. The relationship between hydrogen and hydroxyl ions thatindicates the acidity or alkalinity of a soil

d. The study of soils

e. A measure of soil pH thats less than 7

f. An organic colloidal component of soil resulting from theenzymatic breakdown of plant tissue

g. The arrangement of soil particles into aggregates

h. A type of transported soil resulting from the movement ofwater

i. A measure of soil pH thats greater than 7

j. An element that can make up 25% of the volume of soil

Lesson 1 21

ASSIGNMENT 4: PLANT GROWTHREGULATORS



Growth Regulators Defined

Just like you, plants produce chemical compounds that affect

their growth. In both plants and humans, these naturally

occurring chemical compounds are called hormones.

Hormones specifically related to plants are sometimes

referred to as phytohormones. Plant hormones control normal

plant functions such as root growth, stem elongation, and

other developmental processes. Plant hormones also deter-

mine the formation of flowers and leaves, the timing of leaf

senescence (the falling of leaves), the development and ripen-

ing of fruit, and even the ultimate death of a plant. Unlike

animals that have specialized glands that produce hormones

and a circulatory system that transports them, every plant

cell is capable of producing hormones that may exert their

effect in a completely different part of the plant. Just as in

the animal kingdom, hormones are vital to plant growth.

Without them, plants would most likely appear and function

in ways other than what were accustomed to.

Types of Growth Regulators

Plant growth regulators (PGRs) may occur naturally. Some

examples are auxins, gibberellins, and cytokinins (see

pages 6771). Other PGRs may be man-made. These com-

pounds mimic the functions and processes of naturally

occurring plant hormones. Theyre used in agriculture and

ornamental horticulture to achieve various growth character-

istics in plants and to enhance the desirable traits in food

crops and those same traits in ornamental plants.

Textbook Note

On page 71 of your textbook in the second full paragraph, the wordkinetic (line 3) should be kinetin.

Garden Ecology22

The table below illustrates some of the more commonly used

PGRs, along with their functions and practical uses.

The use of plant growth regulators is less common among

landscapers than among those who grow agricultural and

ornamental crops. Nevertheless, if youre going to be working

in the landscaping field, you should have an awareness of the

effects that PGRs have on plant growth. You should also be

familiar with their potential uses and associated benefits. All

of these are valuable tools professional landscapers may use

in managing landscapes under their care. Here are two good

examples how this knowledge can be helpful:

1. Knowledge of a plants normal response to maintenance

practices such as trimming and pruning will allow you to

propose solutions to plant maintenance problems with

known results rather than by trial and error.

2. Plant growth retardants have been developed for use on

turfgrasses in an attempt to slow their rate of growth.

Applying these retardants properly to plants can give a

return in investment many times over in reduced labor

hours, fuel costs, and dumping/recycling fees.


Achievement Review on page 76 of the textbook to help you

review what youve just studied. Once you understand the

material, move on to Assignment 5.

PGR Function Practical Uses

Auxins Promote or inhibit growth Stimulate root growth on plant cut-tings; encourage flower formation

Gibberellins Stimulate cell division and enlargementIncrease stalk length; enhance seedgermination and fruiting

Cytokinins Stimulate cell division andshoot formationProlong storage life of flowers andvegetables; stimulate bud initiation

Ethylene Influences leaf abscissionand ripening of fruitInduces uniform ripening in fruitsand vegetables

Abscisic acid Inhibits growthPrevents greenhouse plants frombecoming too tall or leggy; can promote early fruit and leaf drop

Lesson 1 23

Self-Check 4


______ 1. Auxins

______ 2. Geotropism

______ 3. Gibberellins

______ 4. Cytokinins

______ 5. Ethylene

______ 6. Parthenocarpic

______ 7. Rosetted

______ 8. Hormones

______ 9. Growth retardants

______ 10. Abscisic acid


a. Growth habit of plants with good leaf formation butretarded intermodal growth

b. A term used to describe fruits without seeds

c. A naturally occurring growth inhibitor that counters theeffects of gibberellins

d. Plant hormones that both promote and inhibit plantgrowth

e. Naturally occurring compounds that influence plant growthand development

f. A term used to describe the response of auxin to gravityand the resulting growth reaction in plants

g. A group of plant hormones that promote cell enlargementand increases in plant height

h. Naturally occurring hormones that promote the division ofplant cells

i. A type of plant growth regulator that promotes the ripen-ing of fruit

j. Generic term used to describe growth regulators used inthe landscape trade to slow the growth of turfgrasses

Garden Ecology24

ASSIGNMENT 5: PLANT REPRODUCTION



The study of plant reproduction and plant breeding may

seem more appropriate to students pursuing a degree in

botany or greenhouse production. However, a basic under-

standing of the ways in which plants are produced for sale

to the landscape industry will enable you to make informed

choices when purchasing plants for your next landscape

project. After reading the material in your textbook, you may

decide to grow and propagate some plants yourself rather

than purchase them from a greenhouse or nursery. Many of

the plant reproduction techniques presented in the textbook

can be easily achieved with limited investment in tools and

materials. Many landscape professionals have incorporated

this aspect of ornamental horticulture into their business

plans, finding it to be both profitable and fun.

Sexual and Asexual Reproduction

Plants reproduce through either sexual or asexual

reproduction. Sexual reproduction relies on the formation

and pollination of flowers, followed by the development and

germination of seeds. When plants pollinate themselves, the

resulting plants are almost identical to the parents. When

plants pollinate with other plants, the resulting plants are

similar to but different than both parents because two sets

of chromosomes are combined to form one plant.

Asexual reproduction occurs through many different means

that bypass the lengthy flower-seed germination process.

Instead, this process of reproduction uses the vegetative

parts of a plant to produce an entirely new plant. Examples

of such vegetative parts are runners, stolons, sucker shoots,

bulbs, stems, and even leaves. These parts are described on

pages 8184. The plant that results from asexual reproduc-

tion is almost identical to its parent because theres no

combining of chromosomes from different plants.

Lesson 1 25

Asexual reproduction allows plant breeders to make exact

duplicates of plants. While asexual reproduction provides

more reliable results, theres concern that without the cross-

pollination and mixing of chromosomes of sexual reproduction,

plants are unable to adapt or evolve in response to changes

in their environment.

The propagation of plants for use in the landscape trade is

generally carried out by those in the greenhouse and nursery

industry; however, the ease with which some plants can be

propagated makes it feasibleand profitablefor landscape

contractors as well. For example, because dividing a plant

crown is perhaps the easiest method of plant propagation,

landscape contractors would be wise to perform this job

themselves. Many shrubs and most herbaceous perennials,

such as the ever-present daylily or hosta, are easily divided

into two or more new plants by simply digging up the parent

plant and slicing it into smaller sections with a sharp shovel

or knife. These new divisions can then be planted back into

the garden or potted for use on another job.

At first read, some of the material in Chapter 5 of your text-

book may seem a bit overwhelming and difficult to follow. Try

not to get too hung up on the details. Instead, concentrate on

the overall concepts presented, rereading pages that cover the

more complex concepts of plant reproduction as needed.




the material, move on to the examination for Lesson 1.

Caution

Many plants developed by plant breeders are patented. Because theycarry trademark protections, its illegal to propagate and sell theseplants without first paying a royalty fee to the breeder.

Garden Ecology26

Self-Check 5

Match each term in the left column below with its definition in the right

column.

______ 1. Asexual reproduction

______ 2. Layering

______ 3. Propagation

______ 4. Clone

______ 5. Stratification

______ 6. Runner

______ 7. Bulb

______ 8. Grafting

______ 9. Cuttings

______ 10. Gregor Mendel


a. The deliberate controlling and manipulation of plant reproduction

b. A propagation method in which two plants are joined andeventually become one plant

c. Pieces of plants removed for the purpose of propagation

d. A modified stem or root tissue that stores food duringdormant periods

e. A stem that grows along the ground surface forming newplants at the nodes

f. A process in which new plants are produced without theformation of seeds

g. An Augustinian monk who utilized the common gardenpea to study plant genetics

h. An exact duplicate of the parent plant achieved throughasexual means

i. A means of plant reproduction in which roots form on astem still attached to the parent plant

j. The exposure of seeds to low temperatures necessary forseed germination

Garden EcologyIn Lesson 1, you learned the fundamentals of plant and soil

science. In this lesson, youll build upon what youve learned

about plants and soils by reviewing basic concepts and mate-

rials and by studying the complex interactions that occur

between plants, soils, and their surrounding environment.

This holistic approach to the study of plants, soils, and other

living organisms in the environment is the branch of science

known as ecology. While ecology can be studied at many lev-

els, the focus of this lesson is on the ecology of smaller-scale

landscapes and gardens. It also considers the influences and

roles played by human beings in the workings of these envi-

ronments. All of the assigned readings for this lesson are in

the textbook Ecology for Gardeners.

Assignment 6 provides a review and deeper explanation of

basic concepts and terms used in describing plants and the

way in which they function. Assignment 7 introduces you to

the many other living organisms besides plants and the roles

they play in a healthy ecosystem. Assignment 8 examines

the environmental factors, including the nonliving mineral

substances, that influence plants. Assignment 9 covers the

interactions of plants with natural forces and mineral

substances. Assignment 10 discusses the influences of com-

petition and mutualism in the garden environment. And

finally, Assignment 11 focuses on the role human beings

play in the stewardship and management of the garden

environment.

OBJECTIVES


Use the proper scientific terms to describe the basic

parts and structure of a green plant

Describe the life cycle and various stages of growth and

development of a green plant

List and categorize the living organisms other than

plants that may inhabit the garden environment

27

Le

ss

on

2L

es

so

n 2

Garden Ecology28

Discuss the effects that other living organisms can have

on plant growth

Outline the environmental factors that influence plant

growth and soil formation

Summarize the primary energy inputs in the garden

environment

Describe the material cycles and their importance in the

garden environment

Characterize the interactions of plants with the natural

forces of heat, light, and gravity, along with other forces

that influence plant growth and development

Discuss the interactions of plants with mineral

substances

Describe the concept of plant communities and their

variation in space and time

Explain the concept of biodiversity

Summarize the interactions among garden organisms,

including competition, herbivory, predation, parasitism,

and mutualism

Provide an overview of the concepts of stewardship and

holistic management of the garden environment

ASSIGNMENT 6: THE NATURE OF PLANTS


in your textbook, Ecology for Gardeners.

The love of plants often draws people to the landscape

professionand for good reason. Plants are fascinating in

their ability to transform the energy of the sun into food that

sustains all higher life-forms, including humans. Plants also

provide the raw materials people use to build shelters, pro-

duce medicines, and make the fibers used in the manufacture

of clothing and paper products of all sorts. The energy that

powers todays world economy ultimately finds its source in

Lesson 2 29

the plants that covered the globe millions and millions of

years ago. For all that plants provide, landscape professionals

generally consider them as the foremost building blocks from

which attractive gardens and landscapes are made.

Just as a pre-med student must learn about the human

anatomy before working with patients, a landscape profes-

sional must also become familiar with the nature of plants

prior to successfully using them in a landscape. Make that

your goal as you study Chapter 1.

As you read the material in Chapter 1, you may begin to

wonder why you need to learn so much about plant parts

and about the way in which plants grow, develop, and repro-

duce. The answer is simple: Many of the books youll be

using as a landscape professional use this information to

describe and identify plants. If youre unfamiliar with these

terms, youll find it difficult to identify and choose plants for

a landscape project.

Much of the material youll study in this assignment was

introduced in Lesson 1. Let this assignment serve as a both a

review and further study of plants from another perspective

information that will reinforce your understanding and

appreciation of the subject matter.

Now, take a moment to complete Self-Check 6 to help you



Garden Ecology30

Self-Check 6


______ 1. Nodes

______ 2. Conifers

______ 3. Stomates

______ 4. Rhizome

______ 5. Root hairs

______ 6. Mycorrhizae

______ 7. Cotyledons

______ 8. Genus

______ 9. Meristems

______ 10. Species


a. The first of the two-part Latin name given to each plant

b. Horizontal stems below the soil surface that produce roots andnew shoots

c. Points along the stem at which leaves and branches arise

d. Plants that generally have needle-shaped leaves or flat, narrowleaves that remain on the plants for several years

e. The second of the two-part Latin name given to each plant

f. Plant tissue where new cells form from the division of existingcells leading to plant growth

g. Pores on the surface of a leaf that allow water vapor to escapeduring the process of transpiration

h. The points along a plants root where the great majority of wateris absorbed

i. The parts of plants that provide a source of energy to newlyemerging seedlings prior to the formation of true leaves

j. Associations between plant roots and soil-borne fungi in whicheach usually benefits from the other

Lesson 2 31

ASSIGNMENT 7: OTHER GARDEN INHABITANTS

Read the following material. Then read Chapter 2 (pages 4790)

in your textbook, Ecology for Gardeners.

Imagine that youre standing in the middle of a very large,

empty parking lot or in a barren desert on a hot summer day.

What do you see? What do you hear? Chances are you dont

see or hear much in the way of any life-form. Now put your-

self in the middle of a prairie on that same hot summer day,

and what do you see and hear? More than likely, youll hear

the buzzing sound of bees and wasps as they hover around

the multitude of prairie flowers and grasses. Youll see grass -

hoppers jumping from the tall grasses, hawks soaring on the

warm breezes above, and if youre lucky, a small herd of buf-

falo rumbling by. Now wander inside the cool shade of the

wooded ravine at the edge of the prairie and notice the sala-

manders and frogs in a shallow pool of water, a snake

winding its way through the bulrushes, and a spider making

a meal of the unlucky fly trapped in its web. Take a break on

the trunk of a fallen tree and notice the roaming army of ants

and the centipedes that scatter when you lift a piece of rotting

bark. Pick up a stick and brush aside the layer of decaying

leaves and twigs and take notice of the red worms and

ground beetles going about their business. Pick up a handful

of soil and take a closer look with your pocket lens and

observe the array of microfauna that go unnoticed to the

naked eye.

Now what does all that mean? Simply this: A landscape

devoid of plants is most likely going to be deficient in other

life-forms as well. On the other hand, a landscape with

plants will most likely be occupied by a diversity of animal

life. Some of these life-forms may be considered a nuisance

as in the case of a hungry deer that nibbles the succulent

growth of your hosta to the ground or a rabbit that lops the

flowers off your tulips just as theyre about to bloom.

However, others, such as the worms that aerate and enrich

the soil with their castings and the bees and wasps that polli-

nate flowers, are essential to the functioning of a garden

ecosystem. For a landscape professional, an understanding

Garden Ecology32

and appreciation of the complex relationships between

plant and animal life in the garden environment are vital to

the care and stewardship of man-made landscapes.

In this assignment, youll be introduced to the nonplant

garden inhabitants that play vital roles in the functioning of

healthy garden ecosystems. Some, like hungry rabbits, are

readily recognizable and easily identified as either helpers or

nuisances to gardeners. However, others, like nematodes and

bacteria, may not be recognized so easily. An untrained eye

may jump to the conclusion that many of these less familiar

organisms are only something to be reckoned with and

immediately reach for the can of bug spray. In fact, these

organisms may be doing landscape plants a favor. Learning

to first identify and then separate the good guys from the bad

is the first step in maintaining healthy ecosystems while doing

as little harm as possible.

In reading through your textbook, try not to be intimidated

by the sheer number of hard-to-pronounce scientific names

of individual organisms. Instead focus on the big picture to

gain an appreciation of the diversity of life-forms in the gar-

den and how each contributes to a balanced and healthy

ecosystem.




Lesson 2 33

Self-Check 7


______ 1. Animals

______ 2. Herbivores

______ 3. Metamorphosis

______ 4. Caterpillars

______ 5. Omnivores

______ 6. True bugs

______ 7. Hymenoptera

______ 8. Detritivores

______ 9. Insects

______ 10. Earthworms


a. Organisms that consume decomposed organic material

b. The larval stage of moths and butterflies

c. Organisms that are unable to photosynthesize and are composedof more than one cell

d. Organisms with three distinct body segments, including a head,a thorax, and a posterior abdomen

e. Organisms that eat both plants and animals

f. A term used to describe the multiphase life cycle of insects

g. Organisms that eat plants or plant parts

h. Organisms called the saints of the garden

i. Generally the most beneficial of all insect groups, which includesants, bees, and wasps

j. Relatively soft-bodied insects that have piercing-sucking mouthparts and undergo incomplete metamorphosis

Garden Ecology34

ASSIGNMENT 8: THE GARDEN ENVIRONMENT

Read the following material. Then read Chapter 3 (pages 91

122) in your textbook, Ecology for Gardeners.

Up until this point, the focus of Lesson 2 has been on the

living constituents of plants and animals in the garden envi-

ronment. While plants and the animals that feed on these

plants are of great concern to landscape professionals, the

physical elements of sunlight, air, water, and soilalong with

their influences on the health of gardens and landscapes

deserve equal consideration in the study of designing and

caring for these unique environments.

Sunlight

As youve already learned, sunlight is the ultimate source of

all energybe it the gasoline that powers your rototiller, the

food you eat that keeps you going, or the direct rays of sun-

light that make garden plants grow. How gardeners and

landscape professionals make use of this amazing source of

energy rests on their knowledge of the physical properties of

sunlight, how it changes from one geographic location to

another, and how it changes throughout the year.

Air

The air that surrounds people and plants in the environment

is influenced by the energy of the sun. It, too, is an important

factor in the health of both plants and animals. While its

impossible to actually see the individual components that

comprise the atmosphere, a basic understanding of its chem-

ical makeup and the way in which it influences everything

from plant vigor to the health of soils will enable you to better

care for plants in the landscapes youre responsible for. To

better appreciate the influence air has on plants, consider the

wilting effects on a newly planted tree from a hot, dry, sum-

mer breeze or the sinking of cold air from high ground that

settles over a low spot in the landscape, resulting in an early

autumn frost and an abrupt end to the life of your coveted

tomato plants.

Lesson 2 35

Natural Waters

A sufficient supply of water is often the difference between a

healthy plant and a dead one. The lack of waterif all other

needs of the plant are being metcan be the limiting factor

to a plants success. The most obvious effects that wateror

the lack of itcan have on an ecosystem can be seen in

places like the desert in the southwestern United States,

where this lack of water has a profound effect on the quan-

tity, size, and types of plants and animals that are able to

survive in the arid environment. As detrimental as the lack of

water may be to the survival of plants and animals, an over-

abundance of water can have equally unfavorable effects on

plant health. Saturated soils can become anaerobic and toxic

to plants. Water also affects the movement of soil nutrients

in a process known as leaching that over time can remove

essential soil nutrients. Such soil becomes unsuitable to

many plants unless chemical fertilizers are added to it.

An understanding of the physical properties of water and its

effects on plant and soil health is yet another vital compo-

nent in the successful handling of garden environments.

Soil

Often seen as nothing more than the medium by which

plants anchor themselves to the earth while absorbing the

nutrients and water essential to their survival, soil is a pre-

cious resource that through ignorance and neglect is being

depleted at alarming rates. In many instances, soils that have

taken hundreds and even thousands of years to form are

simply stripped away during the land development process,

rendering the site inhospitable to the sustainable growth of

plants. In such instances, common practice is to spread a

thin layer of topsoil over the disturbed ground after buildings

and roads have been constructed. However, the soil that

results is far from that which was there before the develop-

ment process began. If plants are to prosper and thrive in

such soil, some degree of remediation of the soils is required.

To carry out the vital process of rebuilding a healthy soil,

landscape professionals must possess knowledge of the com-

ponents and processes that form healthy soils. Armed with

this knowledge, along with an understanding of the many

The term anaerobicmeans without oxygen.

Garden Ecology36

nutrient cycles that are critical to maintaining soil health,

landscape professionals avoid the costly mistake of taking

the soil for granted.




Self-Check 8


______ 1. Loam

______ 2. Sunlight

______ 3. Humus

______ 4. Anaerobic

______ 5. Nitrogen

______ 6. Transpiration

______ 7. Limiting factor

______ 8. Material cycle

______ 9. Oxygen

______ 10. Clay


a. The gas that comprises 7880 percent of the air in the loweratmosphere

b. A process that results in the greatest loss of soil water throughthe leaves and stems of plants

c. A series of transformations in which a substance begins andends in the same form

d. An energy source that drives evaporation, wind currents, and the process of photosynthesis

e. A soil-borne substance composed of very large organic mole-cules derived from the remains of dead plants, animals, andmicrobes

f. A soil with a more-or-less balanced blend of sand, silt, and clayparticles

g. The gas that comprises 1820 percent of the air in the loweratmosphere

h. A type of soil thats prone to shrinking, swelling, and compaction

i. A critical resource or factor whose deficiency or excess limits thegrowth of a plant

j. A condition in which free oxygen is scarce or absent such as instagnant water or compacted soils

Lesson 2 37

ASSIGNMENT 9: PLANTS IN THE ENVIRONMENT



To survive in the environment, plants must be fighters, or

they at least must be able to adapt to the whims of nature.

Unlike animals, plants lack the ability to move about in

search of food, water, warmth, or even a mate. To make up

for this lack of mobility, plants have many clever ways in

which to adapt to surrounding environmental conditions.

The ability of plants to adapt in response to natural forces

such as heat and light, or to the physical and mineral prop-

erties of different soil types has resulted in an astounding

diversity of plant life here on Earth, each precisely suited to

the unique environment in which it grows.

Interactions of Plants

with Natural Forces

Heat

When selecting plants for a garden, landscape professionals

give their greatest consideration to two criteria: plant hardi-

ness and sunlight requirements. As youve already learned,

plant hardiness refers to the ability of a particular plant to

survive a minimum cold temperature. This factor is a very

important consideration in the selection of appropriate plants

for a garden. In addition, duration and variation in air tem-

perature play equally significant roles in the life cycle and

survival of many plant species in temperate climates.

Light

The second consideration is sunlightin particular, how

much sunlight a particular plant needs to flower, set fruit,

and thrive in a landscape. To expect a plant that has existed

for years in the moist, shaded rainforest environment of the

Pacific Northwest to suddenly adapt to the blazing sun of an

Garden Ecology38

arid and treeless backyard in Texas is a lot to ask. And con-

versely, the sun-loving prairie blazing star that blooms so

profusely in the open prairie wont flower the way you had

hoped when planted in your customers shaded backyard.

Interactions of Plants

with Mineral Substances

After temperature and sunlight requirements, soils and their

mineral makeup, along with moisture levels, are probably the

next most significant limiting factors in the survival of plants.

Minerals

The creation of soil, which occurs over a long span of time, is

directly influenced by the underlying parent material of rock

and other mineral formations. The plants that grow in associ-

ation with these varied soil types are specially adapted to

them. Therefore, theyll perform poorly when suddenly placed

in soils of a different composition.

Consider this example: People have tried to plant an acid-

loving rhododendron in a limestone-based, alkaline soil.

These attempts generally result in failure. While soils can be

modified and made more hospitable to certain plants through

the addition of various minerals and nutrients, this task can

be quite expensive on a large scale and can easily be avoided

by selecting plants suited to the soils youre working with.

Water

In nature, water is often the most critical limiting factor in

plant survival. With the aid of aqueducts and irrigation

ditches in pre-modern times and the garden hose and exten-

sive underground irrigation systems of today, people have

found a way around the limiting factor that a lack of water

can present. The problem, however, is that this artificial

means of sustaining plants has tremendous environmental

costs. Therefore, planting indigenous species in favor of

exotic species that may not be adapted to local conditions

should be strongly considered.

Lesson 2 39

Although the lack of water is a definite limiting factor, too

much of it can be equally limiting to plants ability to thrive

in the landscape, as many a drowned Japanese yew can

attest.

While some of the effects on plants from too much or too lit-

tle water can be quite obvious, others such as the leaching of

nutrients from the soil go unnoticed but can have significant

consequences on soil fertility and plant health. Chapter 4 in

your textbook goes into more detail on the effects of water

and other soil nutrients essential to plant health and their

influences on evolution of plant communities.




Garden Ecology40

Self-Check 9


______ 1. Vernalization

______ 2. Sexual

reproduction

______ 3. Respiration

______ 4. Etiolation

______ 5. Water

______ 6. Hardening off

______ 7. Pruning

______ 8. Nitrogen

______ 9. Potassium

______ 10. Sodium


a. The growth condition involving excessive stem elongation andpale color, usually due to inadequate light levels

b. The practice that compensates for root loss in perennials duringtransplanting

c. A chemically inert substance that must be converted before itcan be used by plants

d. The plant process thats especially sensitive to excessively hightemperatures

e. A nutrient important to the proper growth of root systems andtheir ability to take up nutrients from the soil

f. In low-light situations, the process that exceeds the rate of pho-tosynthesis and leads to exhaustion of a plants energy reserve

g. The process in which flowering is induced by exposure to a mini-mum period of cold

h. A substance thats highly toxic to plants and devastating to soilstructure; the sixth most abundant element in Earths crust

i. The most critical nutrient for plants and the main source ofhydrogen required for photosynthesis

j. The process of preparing indoor-grown plants for harsher, out-side growing conditions

Lesson 2 41

ASSIGNMENT 10: INTERACTIONSAMONG GARDEN ORGANISMS



The study of plants, animals, and the nonliving components

of the garden environment is a logical first step in under-

standing the ecology of gardens. The next important step is to

consider the ways in which these living organisms interact

with each other and their surrounding environment. A simple

way to consider these interactions is to determine whether

the effects they have on one another are positive or negative.

For example, a caterpillar that feeds on the leaves of a young

tree is fat and happy, while the tree has been stripped of all

of its leaves1 for the caterpillar, 0 for the tree. Then, in flies

a bird that eats the plump caterpillar1 for the bird, 0 for

the caterpillar. Its not always clear who are the winners and

losers as new players continually join the game. What should

be clear, however, is that something seen as negative at one

point may later be perceived as positive. As a landscape pro-

fessional, you should approach your study of gardens and

landscapes from a holistic and ecological point of view. Such

a view is much more challenging and interesting than the

shortsighted approach that sidesteps the wisdom of nature

in favor of the quick fix at the end of a spray nozzle.

Competition

Competition among organisms can be classified as either

intraspecific, in which individuals of the same species com-

pete against each other, or interspecific, in which organisms

of differing species compete for the limited resources in the

environment. Plants have developed an amazing array of

mechanisms that allow them to compete with other plants in

their quest for the limited resources in the environment. One

example of such a mechanism is very familiar to gardeners

who have tried to plant a garden in the vicinity of a black

walnut tree. This particular species of tree has the ability to

produce the chemical compound juglone, which is toxic to the

other plants around it. Other tactics such as early or rapid

Garden Ecology42

growth, the ability to survive in a wide range of growing

conditions, and the ability to produce and disperse prolific

amounts of long-lived seeds over great distances are exam-

ples of a plants competitive abilities.

Plants arent always in direct competition with each other,

however. At times, plants cooperate by occupying different

niches in the environment. For example, in forest environ-

ments, the shade-loving groundcover plants thrive in the

shadow cast by overhead canopy trees.

Herbivory

Perhaps more menacing to plants than the competition

among plant species is the threat of herbivory, in which all

or part of a plant is consumed by other organismsincluding

people. Herbivory comes in many forms:

The chewing of leaves by hungry caterpillars

The draining of a plants vital fluids by thirsty aphids

The consumption of fruits and seeds by birds and

mammals

In response, plants have developed both physical and chemi-

cal methods to deter predators. For example, some plants

have stiff bristles on the surface of their leaves and stems,

and others produce bitter-tasting tannins. While a certain

level of herbivory is basic to the normal functioning of the

food web, populations of certain organisms may occasionally

become a detriment to the garden environment and peoples

desire for some level of control over nature.

As a landscape professional, you should have the ability to

maintain a certain level of control in the garden. This ability

begins with a basic understanding of the various methods by

which plants are preyed upon by other organisms and the

methods of identifying the culprits. Specific actions you can

take to control the spread of unwanted plant pests are cov-

ered in forthcoming assignments.

Lesson 2 43

Other Interactions

Chapter 5 also covers the topics of predation, parasitism, and

the win-win interactions among garden organisms known as

mutualism. A mutualism familiar to many gardeners is that

which occurs between the Rhizobium bacteria and plants in

the legume family, such as peas and beans. In this instance,

the bacteria that live on the roots of a pea plant make it possi-

ble for the plant to absorb atmospheric nitrogen. In return, the

bacteria are allowed to absorb nutrients from the pea planta

win-win situation for both the bacteria and the pea plant.

An appreciation of these and the many other complex inter-

actions that naturally occur among garden organisms will

enable you to work in harmony with, rather than against, the

natural rhythms of the garden ecosystem.




Garden Ecology44

Self-Check 10


______ 1. Alleopathy

______ 2. Seed bank

______ 3. Herbivory

______ 4. Gall

______ 5. Physical defense

______ 6. Tannin

______ 7. Mimicry

______ 8. Parasitism

______ 9. Mutualism

______ 10. Mycorrhizae


a. A situation in which all or part of a plants tissues or fluids areconsumed by another organism

b. A tumor-like growth on leaves or stems that provides shelterand food to invading organisms

c. A form of competition among plants in which one plant releasesa chemical thats harmful to other plants

d. Spines, bristles, and thorns, which serve to protect plants fromherbivores

e. A defense tactic whereby a plant produces plant parts thatresemble other plants in an attempt to confuse or deceive predators

f. A long-term association between two or more species in whichall participants benefit

g. Fungi that live in close association with plant roots, helping themextract nutrients from the soil

h. A buildup of seeds in the soil in excess of what was produced inthe preceding year

i. A chemical defense common in tea leaves and acorns

j. An interaction in which one individual removes nutrients, fluids,or tissues from another over an extended period of time

Lesson 2 45

ASSIGNMENT 11: GARDENINGAS APPLIED ECOLOGY



Putting the Environment First

As a landscape professional, you should always work in such

a way that does as little harm as possible to the natural

landscape. In fact, you should attempt to restore any damage

that may have inadvertently been caused by others.

All kinds of people work in the landscape. Some are simply

backyard gardeners with small vegetable plots; others are

landscape designers who are creating plans for entire yards.

No matter the person, however, the goal should be the same:

to follow the example set by nature and garden or landscape

just as nature does. To illustrate this point, consider the

statement made by architect and author William McDonough

in his book Cradle to Cradle: In nature, the word waste does

not exist. If thats true, then why do so many people rake

the leaves from their yards each fall and send them to the

landfill or compost center instead of composting them in their

own yards where they can nourish the soil the way it happens

in any healthy forest ecosystem? Granted, it isnt always pos-

sible or practical to fully mimic nature in some places and

under certain circumstances, but adherence to this philoso-

phy as the guiding principle in every decision related to

landscapes can result in gardens and landscapes more in

tune with nature and a landscape industry thats a better

steward of the environment.

Most people dont intentionally do things they know are

going to be harmful to the environment. However, many,

through ignorance of the complex interactions that occur in

healthy ecosystems, do so in their attempt to improve the

environment around them. They may plant a tree ill-suited to

existing site conditions that leads to the spraying of harmful

chemicals, or they may attempt to maintain a lush bluegrass

lawn in an arid climate by applying copious amounts of water

Garden Ecology46

and fertilizer. Such decisions result in losing battles that

consume precious resources and work against the laws of

nature.

In your work with landscapes, dont always look for the quick

and easy fix of synthetic herbicides, pesticides, and fertilizers.

In the long run, such solutions often create more problems

than they solve and at unnecessary environmental costs.

Instead, heres a good approach to take with the landscape

environment:

Make concern for the environment a top priority.

Be willing to be patient with low-tech, proven methods.

Stewardship

As you study Chapter 6, youll notice that a key term in that

chapter is stewardship. This term is used in relationship to

soil (pages 240241), water (pages 241242), and the atmos-

phere (page 243).

Soil is a precious, life-supporting resource. To be a good

steward of soil, you can

Help to keep it aerated by maintaining a high level of

organic matter in the soil

Control erosion

Take measures to avoid compacted soil

To be a good steward of water, you can

Follow the principles of xeriscaping by using drought-

tolerant plant species in arid climates

Apply a protective covering of mulch to reduce the

amount of water lost through evaporation

To be a good steward of the atmosphere, you should give

careful consideration to the placement of trees in the land-

scape. Proper tree placement can result in lower ambient air

temperatures as well as lower amounts of energy required to

cool a house on a hot summer day.

Xeriscaping is theprocess of gardening insuch a way to eliminatethe need for supple-mental water fromirrigation.

Lesson 2 47

These simple, low-cost strategies that eliminate the need for

more costly solutions down the line are all part of being a

good steward of the environment and should be standard

procedure rather than the exception to the rule. Other sug-

gestions are presented on pages 240243.

Managing Garden Organisms

Gardens have enemies. Its just a fact of life. These enemies

may be other plants, animals, or insects. Possibly the best

advice for dealing with these enemies is that mentioned on

page 244 of your textbook: From an ecological perspective,

however, it may not be desirable, even if feasible, to utterly

eliminate garden pests. Instead, we should try to manage

both pests and their often more numerous desirable garden

neighbors for the greater welfare of the garden and the envi-

ronment as a whole. Pages 243264 present a variety of

environmentally safe ways to deal with these enemies.

Finally, the last few pages of Chapter 6 cover the ways in

which you can effectively manage plant nutrients, soil

amendments, and energy in a gardenthree important ele-

ments you must consider as a landscape professional.



material, move on to your exam for Lesson 2.

Garden Ecology48

Self-Check 11


______ 1. Terracing

______ 2. Hardpan

______ 3. Landscape fabrics

______ 4. Trap crop

______ 5. Fallowing

______ 6. Crop rotation

______ 7. Companion plant

______ 8. Systemic

______ 9. Green manure

______ 10. Hilltops


a. One ecologically sound way to prevent the growth of weeds

b. A plant species that herbivorous insects prefer over otherplants in a garden

c. One method to reduce soil erosion on steep slopes

d. A technique of starving herbivorous insects by leaving a plotof ground bare for a period of time

e. A plant that either repels harmful organisms or attracts beneficial ones

f. Another term for a cover crop in which plants are grown andtilled into the soil for soil improvement

g. An area that tends to offer longer frost-free growing seasonsthan does land in a valley setting

h. A situation that can be created when soils are repeatedlytilled to the same depth or are walked on when wet

i. A technique to lower herbivorous insect populations bygrowing unrelated plants in succession on the same plot ofground

j. A type of fungicide thats absorbed by a plant and cant bewashed off

Fundamentals of CommonSense Pest ManagementHere are some of the topics youll be studying in Lesson 3:

Common causes of injuries sustained by plants in the

landscape as well as disease and pest problems that can

weaken and, in extreme cases, kill plants

Natures way of controlling pests

How an integrated approach to pest management

utilizing beneficial insects and other less toxic control

methods is better for you and the environment

The strategies and tactics used in an integrated pest

control system that can be implemented in an effort to

lessen the damage done by unwanted garden pests and

the misuse of toxic chemicals

Assignment 12 presents a broad overview of plant pests

and control methods used in maintaining healthy plants.

Assignment 13 is an introduction to natural pest controls

and the fine balance that exists in nature, in which living

organisms (including those considered pests) control their

own populations. In Assignment 14 youll revisit the subject

of integrated pest management (IPM), but in much greater

detail, and youll learn about the various treatment strategies

applied in IPM. In Assignment 15 youll be introduced to the

multitude of beneficial insects and other organisms that are

an integral part of a successful IPM program. Assignment 16

will teach you how to choose the right chemical or microbial

tools along with other useful inorganics, organics, and botan-

icals when beneficial organisms alone won't do the trick.

Finally, in Assignment 17 youll discover the new frontiers of

microbials, pheromones, and insect growth regulators being

utilized in IPM programs today.

49

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Garden Ecology50

OBJECTIVES


Discuss the major causes of injury to plants

List common symptoms of injured plants

Describe conventional methods used in controlling plant

pests

Describe an integrated approach to pest management

(IPM)

Describe natures role in pest management

Identify the treatment strategies and tactics utilized in

an IPM system

List the beneficial insects and other organisms utilized in

IPM

Discuss the conventional use of chemicals in controlling

pests and the ramifications to both environmental and

human health

Describe less-toxic alternatives to pest control

Discuss the use of microbials, pheromones, and insect

growth regulators in an IPM system

ASSIGNMENT 12: PLANTINJURIES AND THEIR CONTROL


135) in your textbook, Ornamental Horticulture.

Assignment

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