The Ecology of Planting Design The Natural Plant Systems

2 The two basic ecological systems for plants a designer must know are the individual system and the population system

3 Within the natural plant community, the individual system is genetically uniform wherever it occurs. An individual plant relates to the other plants around it in two ways: genetically to other members of the same species and ecologically to other plants in the community – forming a plant population system.

4 When a population becomes isolated and begins to inbreed with other groups, it is called a local population. The distribution of plants depends upon their success or failure within the particular system to which they are associated.

5 There are two basic levels of plant distribution. Macrodistribution which is geographic Microdistribution which is ecological

6 A few species of plants are found almost everywhere and are referred to as cosmopolitan species. Others, with restricted distribution are called endemic species. Plants restricted to a given region are called broad endemics. Those restricted to a microenvironments are narrow endemics

7 The presence or absence of a winter season separates the distribution of plants into three groups. arctic-alpine plants adapted to harsh winters temperate plants adapted to different climates pantropical plants found throughout the tropics

8 The relationship between plant systems in a design, are governed by three principal ecological factors: (1) climate, (2) physiography, and (3) soil.

9 Climate The ability of an individual plant to provide a specific planting design function is in part related to the climate conditions that surround it. Climate in this broad sense determines the types of plants that will grow in any given part of a landscape.

10 The climate of the planting design includes: (a) temperature (b) precipitation (c) humidity (d) light (e) wind

11 Temperature determines plant hardiness and growth. Each plant has a minimum and maximum temperature requirement and a range in which it can be effective in a design. (See Temperature Zones Map on Page 5) Temperature determines plant hardiness and growth. Each plant has a minimum and maximum temperature requirement and a range in which it can be effective in a design. (See Temperature Zones Map on Page 5)

12 The limiting factors of temperature are: (1) short growing season (2) unfavorably high or low temperatures (3) harsh winter temperatures (4) temperatures favorable to pests

13 Precipitation Precipitation, in both natural and supplemental form, ranks next to climate in determining plant adaptability for design. It is usually gauged in inches and hundredths of inches and will largely control the distribution of vegetation. Precipitation Precipitation, in both natural and supplemental form, ranks next to climate in determining plant adaptability for design. It is usually gauged in inches and hundredths of inches and will largely control the distribution of vegetation.

14 Water Plants are divided into three groups based upon their adaptability to moisture: hydrophytes - plants that will grow in water or on extremely wet sites mesophytes - plants adapted to medium moisture conditions xerophytes - plants resistant to drought or extremely dry conditions. (See Average Annual Participation map on Page 6)

15 Humidity Humidity is the amount of water vapor in the air, with relative humidity corresponding to the percentage of air saturation. Air can hold more water vapor when the temperature rises; thus when air is heated, relative humidity is lowered, and vise versa. Humidity Humidity is the amount of water vapor in the air, with relative humidity corresponding to the percentage of air saturation. Air can hold more water vapor when the temperature rises; thus when air is heated, relative humidity is lowered, and vise versa.

16 Light Light determines plant growth responses. The most important factors to consider for light are: 1. the placement of the plants 2. their exposure to sun or shade conditions.

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

18 Intensity of light, its brightness and its relationship to exposure requirements for planting. Quality of the wavelength, the relationship of the plant to ultraviolet (400 millimicrons) and/or infrared (760 millimicrons) light rays. Duration, the length of time a plant may need to be exposed to light to produce flowers, seeds, or attractive foliage.

19 Wind The exposure of some plants to winds may directly affect the ornamental adaptability by causing the loss of stem or leaf moisture or reducing its ability to reproduce. High winds, or sudden wind changes, may also cause damage to some plant species or even reduce the amount of water vapor in the air.

20 Physiography The basic physiography of plant communities can be determined by looking at a region’s natural environment. On a micro scale, the local environmental conditions of the site must be determined by careful resource inventory. For a macro scale determination, however, the vegetative regions discussed below are presented for preplanning assistance.

21 The United States is made up of 32 general growth regions, which stretch from the North Pacific Coast to the southern tip of Florida. These regions, in turn, may be divided into various forest and grassland communities. See Plant Growth Regions of the United States, Page 9

22 Soil The solid material covering the surface of a plant community is called soil. It is the major supporter of plant development and its character is the most important factor in natural vegetation.