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1.021.02The Ecology The Ecology

of of Planting DesignPlanting Design

The Natural Plant SystemsThe Natural Plant Systems

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The two basic ecological The two basic ecological systems for plants a designer systems for plants a designer

must know are the must know are the

individual systemindividual systemand theand the

population systempopulation system

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Within the natural plant community, Within the natural plant community, the the individual systemindividual system is genetically uniform is genetically uniform wherever it occurs. wherever it occurs.

An individual plant relates to the other An individual plant relates to the other plants around it in two waysplants around it in two ways: :

geneticallygenetically to other members of the to other members of the same species and same species and

ecologicallyecologically to other plants in the to other plants in the community – forming a community – forming a plant population plant population systemsystem..

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When a population becomes When a population becomes isolated and begins to inbreed with other isolated and begins to inbreed with other groups, it is called a groups, it is called a local populationlocal population. .

The distribution of plants depends The distribution of plants depends upon their success or failure within the upon their success or failure within the particular system to which they are particular system to which they are associated.associated.

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There are two basic levels of plant There are two basic levels of plant distribution.distribution.

MacrodistributionMacrodistribution which is geographic which is geographic

MicrodistributionMicrodistribution whichwhich is ecologicalis ecological

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A few species of plants are found almost A few species of plants are found almost everywhere and are referred to as everywhere and are referred to as cosmopolitan cosmopolitan speciesspecies..

Others, with restricted distribution are called Others, with restricted distribution are called endemic speciesendemic species..

Plants restricted to a given region are called Plants restricted to a given region are called broad endemicsbroad endemics..

Those restricted to a microenvironments are Those restricted to a microenvironments are narrow endemicsnarrow endemics

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The presence or absence of a winter season The presence or absence of a winter season separates the distribution of plants into three separates the distribution of plants into three groups. groups.

arctic-alpinearctic-alpine plants adapted to harsh winters plants adapted to harsh winters

temperatetemperate plants adapted to different climates plants adapted to different climates pantropicalpantropical plants found throughout the tropics plants found throughout the tropics

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The relationship between plant The relationship between plant systems in a design, are governed by three systems in a design, are governed by three principal ecological factors:principal ecological factors:

(1)   (1)   climateclimate,,

(2)   (2)   physiographyphysiography,, and and

(3) (3) soilsoil..

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ClimateClimateThe ability of an individual plant to The ability of an individual plant to

provide a specific provide a specific planting design functionplanting design function is is in part related to the climate conditions that in part related to the climate conditions that surround it. surround it.

Climate in this broad sense determines Climate in this broad sense determines the the types of plants thattypes of plants that will grow in any given will grow in any given part of a landscape .part of a landscape .

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The The climateclimate of the planting design of the planting design includes: includes:

(a) (a) temperaturetemperature (b) (b) precipitationprecipitation (c) (c) humidityhumidity (d) (d) lightlight(e) (e) windwind

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TemperatureTemperature determines plant determines plant hardiness and growth. hardiness and growth.

Each plant has a Each plant has a minimumminimum and and maximum maximum temperature requirement and a temperature requirement and a range in which it can be effective in a design.range in which it can be effective in a design.

(See Temperature Zones Map on Page 5)(See Temperature Zones Map on Page 5)

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The limiting factors of temperature are: The limiting factors of temperature are:

(1) (1) short growing seasonshort growing season

(2) (2) unfavorably high or lowunfavorably high or low temperatures temperatures

(3) (3) harsh winter temperaturesharsh winter temperatures

(4) (4) temperatures favorable to peststemperatures favorable to pests

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PrecipitationPrecipitation

PrecipitationPrecipitation, in both natural and , in both natural and supplemental form, ranks next to climate in supplemental form, ranks next to climate in determining plant adaptability for design. determining plant adaptability for design.

It is usually gauged in inches and It is usually gauged in inches and hundredths of inches and will largely control hundredths of inches and will largely control the distribution of vegetation. the distribution of vegetation.

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WaterWaterPlants are divided into three groups based Plants are divided into three groups based

upon their adaptability to moisture: upon their adaptability to moisture:

hydrophyteshydrophytes - plants that will grow in water - plants that will grow in water or on extremely wet sitesor on extremely wet sites

mesophytemesophytess - - plants adapted to medium plants adapted to medium moisture conditionsmoisture conditions

xerophytexerophytess - plants resistant to drought or - plants resistant to drought or extremely dry conditions. extremely dry conditions.

(See Average Annual Participation map on Page 6)(See Average Annual Participation map on Page 6)

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HumidityHumidityHumidityHumidity is the amount of water vapor is the amount of water vapor

in the air, with relative humidity in the air, with relative humidity corresponding to the percentage of air corresponding to the percentage of air saturation. saturation.

Air can hold more water vapor when Air can hold more water vapor when the temperature rises; thus when air is the temperature rises; thus when air is heated, relative humidity is lowered, and heated, relative humidity is lowered, and vise versavise versa..

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LightLight LightLight determines determines plant growth responses.plant growth responses. The most important The most important factors to consider for factors to consider for light are:light are:

1. the placement of the 1. the placement of the plantsplants

2. their exposure to sun 2. their exposure to sun or shade conditions.or shade conditions.

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When dealing with light for When dealing with light for specific plants, three aspects specific plants, three aspects must be remembered:must be remembered:

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Intensity of lightIntensity of light,, its brightness and its relationship to its brightness and its relationship to

exposure requirements for planting.exposure requirements for planting. Quality of the wavelengthQuality of the wavelength,,

the relationship of the plant to ultraviolet the relationship of the plant to ultraviolet (400 millimicrons) and/or infrared (760 (400 millimicrons) and/or infrared (760 millimicrons) light rays.millimicrons) light rays. Duration,Duration,

the length of time a plant may need to be the length of time a plant may need to be exposed to light to produce flowers, seeds, or exposed to light to produce flowers, seeds, or attractive foliage. attractive foliage.

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WindWindThe exposure of some plants to winds The exposure of some plants to winds

may directly affect the ornamental may directly affect the ornamental adaptability by causing the loss of stem or leaf adaptability by causing the loss of stem or leaf moisture or reducing its ability to reproduce.moisture or reducing its ability to reproduce.

High winds, or sudden wind changes, High winds, or sudden wind changes, may also cause damage to some plant species may also cause damage to some plant species or even reduce the amount of water vapor in or even reduce the amount of water vapor in the air.the air.

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PhysiographyPhysiography

The basic The basic physiographyphysiography of plant communities can be of plant communities can be determined by looking at a region’s natural environment. determined by looking at a region’s natural environment.

On a On a micromicro scale, the local environmental conditions of scale, the local environmental conditions of the site must be determined by careful resource inventory. the site must be determined by careful resource inventory.

For a For a macromacro scale determination, however, the scale determination, however, the vegetative regions discussed below are presented for vegetative regions discussed below are presented for

preplanning assistance.preplanning assistance.

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The United States is made up of The United States is made up of 32 general growth regions32 general growth regions, ,

which stretch from the North Pacific which stretch from the North Pacific Coast to the southern tip of Florida. Coast to the southern tip of Florida.

These regions, in turn, may be divided These regions, in turn, may be divided into various forest and grassland into various forest and grassland

communities.communities. See Plant Growth Regions of theSee Plant Growth Regions of the

United States, Page 9United States, Page 9

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SoilSoilThe solid material covering the surface The solid material covering the surface

of a plant community is called of a plant community is called soilsoil..

It is the major supporter of plant It is the major supporter of plant development and its character is the most development and its character is the most important factor in natural vegetation.important factor in natural vegetation.