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Publication #FOR 91

Chapter 2: Basic Ecological Principles for Restoration1

Mary L. Duryea, Eliana Kämpf Binelli, and Henry L. Gholz2

Welcome to Chapter 2 of the publication Restoring the Urban Forest Ecosystem. This publication consists of 10 chapters available only in PDF format. The chapters explain basic ecological principles for the urban forest's water, soil, and plant and animal communities. They discuss problems common in the urban forest, such as aquatic eutrophication, soil aeration, invasive plants and loss of biodiversity. Solutions, strategies, examples, and additional resources are presented to help make urban forest restoration projects successful.

Abstract

Traditionally the urban forest has been viewed as trees in the city-often along streets and in small groups in other public places such as parks. However, another way to look at the urban forest is as an ecosystem, including many more living components than trees (people, shrubs, herbs, animals, microorganisms), a physical environment (light, moisture, soil, rocks), energy flow from the sun, and water and nutrient cycles. A first step in reorienting our view of urban forests and their management is to review some important ecological principles and to see how they apply to restoration and management. The goal of this chapter is to examine urban forests as ecosystems and to discuss some of the opportunities for managing urban forest ecosystems to provide more natural benefits to communities and cities. By comparing the present state of the urban forest ecosystem (UFE) to natural ecosystems, we can learn how to manage the UFE for some of the natural benefits it can provide. These include energy conservation, stormwater management, wildlife conservation, and recycling or solid waste management. The urban forest ecosystem is an open system with energy and materials constantly entering and leaving the system. Producers (mainly green plants) and consumers (organisms dependent on living and dead plant and animal matter) make up the living portion of all ecosystems which are linked together in complex networks called food webs. Cities are largely consumers relying on production of food, energy, and natural resource from outer agricultural, forested and other natural areas. The urban forest ecosystem can provide many opportunities for ameliorating the drain and stress on our natural resources. For example, by cooling the city with a forest canopy, we are less dependent on outside natural resources for air conditioning. By providing natural areas for water infiltration, storage, and evaporation of rainwater, the waste water from our streets and other impervious surfaces is reduced. When leaves, branches, and grass-clippings are left on-site instead of being removed, these natural materials sustain the natural nutrient cycle and provide the same benefits that we ascribe to mulches in gardens and landscapes. Urban forests can also help reduce atmospheric CO2 build-up in two ways by reducing fossil fuel (energy) use and by increasing carbon storage. Finally, the UFE can provide wildlife habitat and help with the movement and conservation of some organisms through connectivity. Seven guidelines to restore and manage the urban forest ecosystem are (1) Restore and manage the UFE to decrease consumption and contribute to conservation; (2) Restore and manage the UFE for its water cycling benefits; (3) Restore and manage the nutrient cycle within the UFE; (4) Restore and manage the UFE to support greater biodiversity; (5) Restore natural forest ecosystems in the city; (6) Educate policy makers, city managers and the public about the benefits of a healthy UFE; and (7) Incorporate UFE management and restoration into urban and regional planning.

Introduction

Traditionally the urban forest has been viewed as trees in the city-often along streets and in small groups in other public places such as parks (Figure 1). Managing these trees has included inventorying the tree population and assessing their health. We have cultured and managed them mostly as individuals, and this is called arboriculture. However, another way to look at urban forests is as ecosystems, with many more components (people, animals, microorganisms), a physical environment (sidewalks, soil, rocks), energy flow (sun) and processes (water, nutrient cycles) (Figure 2). This ecological perspective is more comprehensive, incorporating biological, physical, chemical and social components. This approach offers a great opportunity to enhance the environmental benefits of forests in urban areas. The environmental benefits gained from a healthy urban forest ecosystem (UFE) include energy savings, reduction of waste and stormwater costs, water quality improvement, increased recreational opportunities and enhanced wildlife and biodiversity conservation. With this outlook we also have the additional opportunity to think in the long-term and to consider the urban forest as part of the larger landscape.

A first step in reorienting our view of urban forests and their management is to review some important ecological principles and to see how they apply to restoration and management. The goal of this chapter is to examine urban forests as ecosystems and to discuss some of the opportunities for managing urban forest ecosystems to provide more natural benefits to communities and cities.

Figure 1. 

Traditionally the urban forest has been viewed as trees in the city-often along streets and in small groups in other public places such as parks.


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Figure 2. 

Another way to look at the urban forest is as an ecosystem with many more components (people, animals, microorganisms), a physical environment (sidewalks, soil, rocks), energy flow (sun), and processes (water, nutrient cycles).


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The Urban Forest as an Ecosystem

An urban forest ecosystem (UFE) is a collection of living matter (plants, animals, people, insects, microbes) and nonliving matter (soil, rocks and dead organic matter) through which there is a cycling of nutrients and water and a flow of energy from the sun. Based on this definition the UFE represents not only the trees but also the other components (including humans, microbes, wildlife and the physical environment) and the interaction of these components.

What are the boundaries of a UFE? We can consider UFEs to be the whole city or smaller parcels within the city. The boundaries of the UFE depend on the nature and scope of our management goals. No matter what the boundaries of the ecosystem are, each ecosystem is linked to other surrounding ecosystems (Figure 3). As we noted above, urban and rural ecosystems also overlap and interact to form landscapes. All the ecosystems on earth together form the biosphere, which contains all of the life on earth.

Figure 3. 

We can consider the UFE to be the whole city or smaller parcels within the city depending on our management goals. The UFE is linked to other surrounding ecosystems, which together form the landscape.


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Why View the Urban Forest Ecosystem as an Ecosystem?

Cities are part of what used to be rural landscapes, most of them originally forested (Figure 4).

Figure 4. 

Cities are part of what used to be rural landscapes. Here you can see the natural forest edges of this small city. Photo by Hans Riekerk


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By comparing the present state of the urban ecosystem to natural ecosystems, we can learn how to manage the UFE for some of the natural benefits it can provide (Figure 5). These include energy conservation, stormwater management, wildlife conservation, and recycling or solid waste management. Also, by taking an ecosystem view, we can better understand the importance of the structure and function of UFEs, which may help solve local problems such as flooding and air and water pollution. By focusing on urban ecosystem management we can also contribute to solving larger scale problems such as biodiversity conservation and reduction of atmospheric CO2 concentrations.

Figure 5. 

By comparing the present state of the urban ecosystem to natural ecosystems, we can learn how to manage the UFE for some of the natural benefits it can provide. Photo by Larry Korhnak


Credit:

Larry Korhnak


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The Structure and Function of the UFE

The UFE is an open system (in thermodynamic terms) with materials and energy constantly entering and leaving (Figure 6).

Figure 6. 

The urban forest ecosystem is an open system with energy and materials constantly entering and leaving the system.


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Energy from the sun is fixed by plant leaves in the UFE. Some of the absorbed energy then flows out of the ecosystem as heat, which warms the air (Figure 7).

Figure 7. 

Energy from the sun is fixed by plant leaves in the UFE.


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The rest of the absorbed solar energy is used to evaporate or transpire water. Materials entering the UFE may be in the form of nutrients (fertilizers), water (in rainfall or irrigation), plants (new plantings or seeds from invasive plants) or other forms of non-solar energy, such as fossil fuels (Figure 8).

Figure 8. 

Fossil fuels are one of the materials entering the UFE for management.


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Forms of these same materials may leave the UFE in runoff (storm water), with the wind (seeds) or in trucks going to landfills (yard and solid waste) with much converted to CO2 and heat (Figure 9).

Figure 9. 

Pruned branches and leaves are materials often leaving the UFE to end up in landfills.


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The UFE may have a very complex structure with a variety of layers including a tree canopy, a shrub understory, an herb layer and a litter layer. The UFE is made up of living things, called biotic components (living plants and animals) and nonliving things, called abiotic components (soil, air, nutrients, water, dead organic matter). Nutrients (such as nitrogen, phosphorus, and calcium) and water cycle from the abiotic parts of the ecosystem to the biotic parts and back again. These are called nutrient and water cycling, respectively.

There are two major groups of the living things in the UFE: (1) producers (also called autotrophs) and (2) consumers (also called heterotrophs) (Figures 10 and 11).

Figure 10. 

One of the two major groups of living things in the UFE is producers (also called autotrophs).


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Figure 11. 

The other major group of living things in the UFE is consumers (also called heterotrophs) which cannot photosynthesize but instead feed directly on the producers (i.e., herbivores), and other consumers (i.e., carnivores and decomposers).


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Producers, which are mainly green plants, take light energy and store it through the process of photosynthesis. Consumers cannot photosynthesize but instead feed directly on the producers (i.e., herbivores) and other consumers (i.e., carnivores or detritivores or decomposers). Consumers include non-photosynthetic bacteria, fungi, and animals, including humans. Producers and consumers are linked together in complex networks called food webs (Figure 12). Food webs are important to recognize in UFE management because the disruption or elimination of one part of the web may impact other organisms and ecosystem functioning in unexpected ways.

Figure 12. 

Producers (mainly green plants) and consumers (organisms dependent on living and dead plant and animal matter) are linked together in complex networks called food webs.


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Comparing Natural and Urban Ecosystems

Natural ecosystems have a balance of production and consumption constantly operating. If by chance the ecosystem produces more than it consumes, the excess energy is stored as carbon (in the wood of tree stems, peat in bogs, etc.). If a fire or another disturbance lowers plant production, the consumer populations will adapt accordingly. Cities, on the other hand, are largely consumers relying on production of food, energy, and natural resources in outer agricultural, forested, and other natural areas (Odum 1983) (Figure 13). Seldom do cities produce these necessities within their perimeter in quantities sufficient to support large numbers of people. At the same time, cities must contend with the wastes that are produced, often sending solid wastes and waste water out of the city.

Figure 13. 

Cities rely on natural and domesticated environments for resources. At the same time these cities must contend with the wastes that are produced, often sending solid wastes and waste water out of the city. Adapted from Odum 1983.


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How Can the UFE Help?

The urban forest ecosystem can provide many opportunities for ameliorating the drain and stress on our natural resources. For example, by cooling the city with a forest canopy, we are less dependent on outside natural resources for air conditioning (Figure 14).

Figure 14. 

By cooling the city with a forest canopy, we are less dependent on outside natural resources for air conditioning.


Credit:

Hans Riekerk


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By providing natural areas for water infiltration, storage and evaporation of rainwater, the waste water from our streets and other impervious surfaces is reduced (Figure 15).

Figure 15. 

By providing natural areas for water infiltration, storage and evaporation of rainwater, the waste water from our streets and other impervious surfaces is reduced.


Credit:

Larry Korhnak


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By providing places for recreation, fewer people will need to use fossil fuels to leave the city for their nature experiences (Figure 16).

Figure 16. 

By providing places for recreation, fewer people will need to use fossil fuels to leave the city for their nature experiences.


Credit:

Larry Korhnak


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By supporting, for example, water quality, forest management, and growth management policies for lands outside our cities, we will sustain our natural and domesticated ecosystems. Infusing our cities and communities with more urban forest ecosystems will restore natural structure and processes to our urban forests making us less dependent on our limited natural resources outside the city.

Characteristics of the UFE

The Urban Heat Island

Cities can reach temperatures 7o to 15o F higher than in the surrounding rural ecosystems. This is called the urban heat island effect (Figure 17).

Figure 17. 

A city is 7o to 15o F warmer than the surrounding countryside. Adapted from Oke 1982.


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Some of the reasons for this heat buildup are:

(1) cities generate heat from burning fossil fuels (factories, cars, heating and air conditioning),

(2) city structures absorb and store solar heat (especially dark surfaces such as asphalt roads and dark roofs),

(3) through decreased vegetation and rapid routing of rainwater to storm sewers, cities have much less natural cooling due to the evaporation and transpiration of water,

(4) air pollutants may slow the outflow of heat away from urban surfaces, and

(5) cities usually have less air movement to take heat out of the city (Lowry 1967; Oke 1982).

Large numbers of trees can reduce local air temperatures by 1o to 9o F (McPherson 1994). Evapotranspiration by trees lowers air temperatures in two ways. First, when precipitation is intercepted by trees and other plants, the evaporation of this water cools the air. Secondly, trees constantly take up water from the soil and lose water to the air. This process, called transpiration, also lowers air temperature. Therefore, the UFE can reduce heat buildup in the city by storing less heat, using more of the sun's energy for evaporative cooling, and shading buildings and other surfaces so that they require less fossil fuel energy for cooling (Figures 18 and 19).

Figure 18. 

The urban forest ecosystem through evaporative cooling and shade can contribute to reducing the temperatures in the urban heat island. This parking lot is a contributor to high temperatures in the urban heat island.


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Figure 19. 

The urban forest ecosystem through evaporative cooling and shade can contribute to reducing the temperatures in the urban heat island. This parking lot demonstrates trees properly placed to reduce temperature.


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Nutrient Cycling in the UFE

Chemicals circulate from the plants and animals to the soil and back again as part of the nutrient cycle (Figure 20). The health of plants in the ecosystem is mainly dependent on the soil for its source of nutrients. Dead organic matter in the soil, also called detritus, is the long-term storage site for essential nutrients. Decomposers (primarily microrganisms) break down the detritus and release the nutrients held in the organic matter into organic forms that can be reused by plants, thus completing the nutrient cycle. In the UFE, this cycle is often disrupted or arrested because most of the dead organic material such as lawn clippings, leaves, branches, and logs are removed and hauled to landfill sites or chipped for application to other sites. By doing so, we are denying the UFE of a readily recyclable source of fertilizers, which then must be imported in the form of man-made fertilizers.

Figure 20. 

Chemical elements in ecosystems circulate from the plants and animals to the soil and back again, as part of the nutrient cycle.


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What happens when we remove these natural materials from a backyard, a park, or a schoolyard in the UFE?

  • The soil may be exposed, resulting in erosion.

  • Plant roots may be exposed and desiccated or damaged (Figure 21).

Figure 21. 

When natural plant materials are removed from a landscape, many plant roots may be exposed and desiccated or damaged.


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  • Fossil fuels are used to blow leaves, clean the site, and transport the yard waste to landfills or compost piles (Figure 22).

Figure 22. 

Many leaves and branches that could be piled or spread (recycled) in a homeowner's landscape are instead transported to landfills or urban compost piles.


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  • The organic matter removed no longer helps the moisture and nutrient holding capacity of the soil.

  • Wildlife and other organisms that depend on decaying wood or litter for habitat and/or food cannot live in this neatly maintained environment.

  • Precious plant nutrients are removed often requiring fertilizer applications for replacement (Figure 23).

Figure 23. 

Precious plant nutrients are removed from the landscape either resulting in plant deficiencies or requiring fertilizer applications.


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• fertilizers, water, mulches, and pesticides brought in to support and maintain this altered system are manufactured at a great fossil fuel cost.

Instead of using tremendous amounts of energy to remove branches, leaves, and snags, we can utilize these materials to sustain the health of the UFE. These natural mulches can be recycled on-site for free where they will serve as natural fertilizers. When they remain on-site, these natural materials provide all the benefits that we ascribe to mulches in gardens and landscapes (Figure 24).

Figure 24. 

When leaves, branches, and grass-clippings are left on-site, these natural materials provide all the benefits that we ascribe to mulches in gardens and landscapes.


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It is quite feasible to take advantage of natural nutrient cycling processes in UFE, contributing in the process to conservation (water, energy, and soil) and improving the environment both locally and globally. Landscapers need to change many ingrained practices, such as leaving more dead plant materials on the ground. Creating "natural" or "semi-natural" areas in parks, backyards, and other appropriate sites will have favorable results for nutrient cycling and other UFE processes such as cycling.

Water Cycling in the Urban Forest

Water forms a critical link between the earth's surface and the atmosphere. After water falls to earth as rain (and in other forms), it flows downhill into creeks or soaks into ground, entering the ground water (Figure 25).

Figure 25. 

In the water cycle, water falls to the earth as precipitation, enters the ground or flows as runoff to rivers, lakes and the ocean, and is taken up (used) by plants and other organisms. By evaporation from vegetation, land, and bodies of water, water re-enters the atmosphere to begin the cycle once again.


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By evaporation from vegetation, land and bodies of water, water re-enters the atmosphere to begin the cycle once again.

Water in creeks flows into rivers, lakes, and finally the ocean. Water reenters the atmosphere by evaporation from the land and sea and and by evaporation and transpiration from vegetation (see Chapter 6 - The Hydrological Cycle). In the UFE, impervious surfaces such as buildings, paved streets and parking lots interrupt this water cycle by collecting the water and channeling it into sewers, canals and other structures.

The consequences of interrupting the natural water cycle include:

  1. decreased infiltration of water into soil,

  2. more runoff, which must then be managed and accomodated,

  3. decreased water quality as pesticides, fertilizers and other polluants are concentrated in the collected runoff,

  4. erosion of unprotected soils and

  5. less evaporation of water with its associated cooling effect.

How does the UFE help restore the water cycle? First, vegetation in the UFE intercepts rainfall and evaporation of this water helps cool the city. Second, soils absorb water; then it is either taken up by plants or percolates to the water table or creeks instead of running into storm sewers. The result is lower stormwater treatment costs and less flooding potential in the city (Figures 26 and 27).

Figure 26. 

In the city, impervious surfaces such as buildings, paved streets and parking lots interrupt the water cycle by collecting the water and channeling it into sewers, canals, and other structures.


Credit:

Larry Korhnak


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Figure 27. 

Soils in the UFE absorb water; then it is either taken up by plants or percolates to the water table or creeks instead of running into storm sewers.


Credit:

Larry Korhnak


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Also, if soils are protected with mulches and plants, less erosion will result in less sediment entering the water. Wetlands also serve as storage areas for water. Restoring and managing wetlands in cities will lower the rate and volume of stormwater runoff, control floods and erosion and help purify water that will reach the water table. For example, after a storm in Dayton, Ohio, the existing urban forest reduced runoff by 7%. A slight increase in the urban forest canopy could reduce runoff by 12% (Sanders 1984).

Educating policy makers, city managers, and the public about the benefits of vegetation in the UFE and cost-saving potential is essential to more effective management of the water cycle. For further discussion on the water cycle, see Chapter 6 - The Hydrological Cycle.

Carbon Storage and Sequestering by UFEs

Carbon dioxide (CO2) in the atmosphere is increasing globally and is the principal contributor to the expected increase in the greenhouse effect (global warming). The two main sources of CO2 are the burning of fossil fuels and deforestation (Houghton et al. 1996). Trees, litter, soil, and organic matter all store carbon (C). Since organic matter contains 50% C, the more biomass (plant and animal matter) on the earth, the less CO2 in the atmosphere.

In an ecosystem, carbon is taken in as CO2 in the process of photosynthesis (Figure 28). Carbon is either stored as living or dead plant material or consumed by other organisms in the food web. CO2 is also given off during respiration. Forests can store much greater amounts of C in the vegetation and soils than any other type of ecosystem on earth due mainly to the relatively massive storage in tree stems.

Figure 28. 

In an ecosystem carbon is taken in as CO2 in the process of photosynthesis. Carbon is either stored as living or dead plant material or consumed by other organisms in the food web. CO2 is also given off during respiration.


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Can the UFE help to store more carbon? Forests store carbon in their plants, roots, forest litter and animals. One urban study estimated that the 69 million acres of urban forest in the U.S., with an average of 28% canopy cover, store annually a net 6.5 million tons of C (Rowntree and Nowak 1991). However, the whole world puts out 5.4 billion tons C per year (deforestation alone accounts for 1.6 billion tons) (Sundquist 1993). Urban forests in the USA, therefore, currently remove only 0.1% of the output. Even though urban forests are not likely to be better managed just for C sequestration, it is important to recognize that C sequestration by the UFE is an additional benefit, albeit small.

To summarize, the UFE can contribute to reduce atmospheric CO2 in two ways: First, by reducing fossil fuel (energy) use in the cities (Figure 29); Second, by increasing C storage from planting and managing trees especially in cities where tree cover is currently low.

Figure 29. 

The UFE can contribute to reduce atmospheric CO2 by reducing fossil fuel (energy) use in the cities.


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Wildlife in the UFE

Urbanization and urban sprawl have resulted in habitat loss, highly fragmented forests, drained wetlands, and disrupted migration routes for wildlife. Also, in many situations wildlife is dependent upon two or more ecosystems, and these may not be available. A forest fragment is a small parcel separated from the larger forest (see also Chapter 3 - Biodiversity). In the UFE, forest fragments often become small parks or undeveloped and often degraded land. These fragments may be too small or too distant to support many wildlife species characteristic of natural areas. However, by connecting some smaller fragments, larger ecosystems can be simulated and some migration routes and habitats restored (Figures 30 and 31). For further discussion on wildlife, see Chapter 8 - Wildlife.

Figure 30. 

This creek outside of a small city is connected to a wetland inside the city allowing migration of some wildlife species.


Credit:

Hans Riekerk


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Figure 31. 

By connecting some smaller fragments, larger ecosystems can be simulated and some migration routes and habitats for wildlife may be restored.


Credit:

Larry Korhnak


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Biodiversity

Until recently, efforts in biological conservation have largely focused on preservation and protection of individual species, subspecies, and populations, through the implementation of the Endangered Species Act. However, scientists and practitioners are realizing today that this has not always been successful or even possible, and that many other species have been ignored as a result. More recently there is a greater focus on ecosystem management with the idea that by managing and restoring whole ecosystems, biodiversity and whole food webs, as well as individual species, may be better protected. Urban forests, which range from highly degraded woodlots to monocultures of exotic trees to semi-natural ecosystems, may play an important role in managing for biodiversity. Although urban forests cannot be expected to support all species groups (for example, large mammals or other wide-ranging animals), if effectively managed, they can provide habitat at a smaller scale, increase the effectiveness of larger nearby reserves, and help with the movement and conservation of some organisms through enhanced connectivity (Figure 32).

Figure 32. 

Although urban forests cannot be expected to support all species groups (for example, large mammals or other wide-ranging animals), if effectively managed they can provide habitat at a smaller scale, increase the effectiveness of larger nearby reserves, and help with the movement and conservation of some organisms through enhanced connectivity. A corridor of forest provides this connectivity.


Credit:

Henry Gholz


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Thus, urban forests can be "stepping stones between ecosystems" (Franklin 1993) (Figure 33). At a smaller scale, biodiversity can also be restored by enhancing the ecosystem's natural structure, creating multi-age ecosystems in several stages of succession, controlling invasive plant and animal species, leaving stumps, leaves, snags, and logs to improve nutrient cycling and for wildlife and by planting native species that mimic composition of nearby ecosystems. (For further discussion, see Chapters 3 - Biodiversity, 4 - Plant Succession and Disturbances, and 9 - Invasive Plants.)

Figure 33. 

Urban forests can be "stepping stones between ecosystems" (Franklin 1993).


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Opportunities for Restoring and Managing the UFE More Ecologically

How can we restore and manage the urban forest ecosystem? We propose the following seven guidelines:

Restore and manage the UFE to decrease consumption and contribute to conservation:

  • Take advantage of natural nutrient cycling by leaving grass clippings, leaves, branches, and logs on the ground and thereby reduce the tremendous amount of energy expended to remove plant materials from the landscape.

  • Plant and maintain trees around buildings to reduce energy consumption for cooling and heating.

  • Save energy used for stormwater management by increasing areas within the UFE for water infiltration and evaporation.

  • Manage the UFE to encourage recreation in the city, thereby decreasing energy consumption for travel to distant recreation sites.

  • Plant tree species that are adapted to local conditions and require only natural rainfall (after establishment) to save water and energy costs from irrigation.

Restore and manage the UFE for its water cycling benefits:

  • Decrease storm water runoff and flooding by increasing pervious surfaces (soils) in the city to absorb water.

  • Encourage increased canopy and vegetation for increased evaporation and transpiration of water to decrease stormwater runoff and treatment costs.

  • Increase the retention of water in the UFE for evaporative cooling to lower urban heat island temperatures.

  • Increase soil water infiltration in UFE soils along with the retention of sediments and pollutants to improve water quality.

  • Restore and manage wetlands in cities to lower the rate and volume of stormwater runoff, control floods and erosion, and help purify water that will reach the water table.

Restore and manage the nutrient cycle within the UFE:

  • Leave grass clippings, leaves, branches, and logs on the ground to decompose and provide nutrients.

  • Use less fertilizers by taking advantage of nutrients that naturally exist and cycle through the system.

  • Rake and distribute on-site mulch in the UFE to protect the soil, retain moisture, and increase the nutrient holding capacity of the soil.

  • Plant less nutrient-demanding species.

Restore and manage the UFE to support greater biodiversity:

  • Include many different species and life forms (herbs, shrubs, trees) in the UFE to provide wildlife habitat and resist disturbances.

  • Restore small ecosystems (with their structure and function) as important connections in the landscape.

  • Restore and manage waterways to connect with other ecosystems.

Restore forest ecosystems in the city:

  • Take a role in restoring natural ecosystems by establishing one on a vacant lot, in a schoolyard, at a park, or another potential site.

  • Restore smaller model ecosystems to serve as demonstration sites for restoration and ecology education.

  • Educate people about the UFE by restoring or improving the health of degraded ecosystems.

  • Reduce deforestation by encouraging developers to retain more green space or larger forest areas in their developments.

Educate policy makers, city managers and the public about the benefits of a healthy UFE:

  • Cost-savings benefits,

  • Recreation opportunities,

  • Tourism benefits of healthy UFE's,

  • Energy-saving,

  • Wildlife conservation,

  • Benefits to natural cycles and recycling,

  • Water quality improvement,

  • Stormwater management, and

  • Carbon sequestration.

Incorporate UFE management into urban and regional planning:

  • Demonstrate how the UFE will benefit regional environmental, economic, and social health.

  • Be involved in the planning process to incorporate UFE management into plans.

  • Educate people to think about the UFE when developing new areas and in downtown redevelopment projects.

  • Consider and educate people about the ecological, economic and social benefits of the UFE at the local to global scale.

Additional Readings

Chameides, W.L., R.W. Lindsay, J. Richardson, and C.S. Kiang. 1988. The role of biogenic hydrocarbons in urban photochemical smog: Atlanta as a case study. Science 241:1473-1476.

Gilbert, O.L. 1989. The ecology of urban habitats. Chapman and Hall, NY.

Gill, D. and P. Bonnett. 1973. Nature in the urban landscape: A study of city ecosystems. Baltimore: York Press.

Goldman, M.B., P.M. Groffman, R.V. Pouyat, M.J. McDonnell, and S.R.A. Pickett. 1995. CH4 uptake and N availability in forest soils along an urban to rural gradient. Soil Biological Biochemistry 27(3):281-286.

Lyons, T.J., J.R. Kenworthy, and P.W.G. Newman. 1990. Urban structure and air pollution. Atmospheric Environment 24B:43-48.

Naiman, R.J., Décamps, H. and M. Pollock. 1993. The role of riparian corridors in maintaining regional biodiversity. Ecological Applications 3(2):209-212.

Vitousek, P.M., P. Ehrlich, A. Ehrlich, and P.M. Matson. 1986. Human appropriation of the products of photosynthesis. Bioscience 36:368-373.

White, C.S. and M.J. McDonnell. 1988. Nitrogen cycling processes and soil characteristics in an urban versus rural forest. Biogeochemistry 5:243-262.

Cited Literature

Akbari, H., S. Davis, S. Dorsano, J. Huang, and S. Winnett. 1992. Cooling our communities: A guidebook on tree planting and light colored surfacing. US Environmental Protection Agency and Lawrence Berdeley Laboratory Report LBL-31587.

Franklin, J.F. 1993. Preserving biodiversity: Species, ecosystems, or landscapes? Ecological Applications 3:202:205.

Houghton, J.T., L.G. Meira Filho, N. Callander, N. Harris, A. Kattenberg, and K Maskell. (eds). 1996. Climate change 1995, the science of climate change. Working Group 1, Intergovernmental Panel on Climate Change, Cambridge University Press.

Lowery, W.P. 1967. The climate of cities. Scientific American 217:15-23.

McPherson, E.G. 1994. Energy-saving potential of trees in Chicago. In Chicago's urban forest ecosystem: Results of the Chicago Urban Forest Climate Project, edited by E.G. McPherson, D.J. Nowak, and R.A. Rowntree. Gen. Tech. Rep. NE-186. Radnor, PA: USDA Forest Service, Northeast Forest Experiment Station.

Odum, E.P. 1983. Basic ecology. Fort Worth, TX: Saunders College Publishing.

Odum, E.P. 1993. Ecology and our endangered life support systems. Sunderland, Massachusetts: Sinauer Associates, Inc.

Oke, T.R. 1982. The energetic basis of the urban heat island. Quarterly Jounal of the Royal Meteorological Society 108:1-24.

Rowntree, R.A. and D.J. Nowak. 1991. Quantifying the role of urban forests in removing atmospheric carbon dioxide. Journal of Arboriculture 17:269-275.

Sanders, R.A. 1984. Urban vegetation impacts on the urban hydrology of Dayton Ohio. Urban Ecology 9:361-376.

Sundquist, E.T. 1993. The global carbon dioxide budget. Science 259:934-941.

Footnotes

1.

This document is FOR 91, one of a series of the School of Forest Resources and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 2001. Revised January 2008. Reviewed November 2012. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Mary L. Duryea, professor and Extension forester, Eliana Kämpf Binelli, former Extension forester, and Henry L. Gholz, professor, School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, PO Box 110410, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.