India: Mumbai’s urban forest

Development preys on Mumbai’s urban forest.

Mumbai, India, is struggling to prevent its growing population of 17 million from infringing on the world’s largest urban forest. This threatens the biodiversity of the forest as well as the security of the inhabitants, as people have been killed by strayed leopards because of the blurred distinction between the city and the countryside.

The larger context of forests ownership and conservation in India is controversial. Forty million of India’s poorest people live in forests, and some of them are pressured by gangs to engage in poaching activities. The government has passed a law to grant forest ownership to long-time forest dwellers, but conservationists fear new illegal settlers might try to take advantage of this measure. Conservation and pro-poor policies are sometimes seen as antithetical.

To read more about Mumbai’s urban forest, and Indian forest conservation in general, see the Financial Express.

Ajax Urban Forestry Study

The implementation of the Urban Forestry Cover Study was approved at Ajax Town Council in June , 2008 - the initial step in the Town’s Urban Forestry Strategy. The study contract was awarded to the Toronto Region Conservation Authority (TRCA).

This is a key corporate initiative that supports the reduction of Greenhouse Gas Emissions throughout the Town. Ajax’s urban forest plays a vital role in the Town’s overall urban health. This study will provide the Town with crucial information on how to build up the local urban forest, and most importantly, how to sustain it.

An urban forest is defined as the sum of all woody and associated vegetation in and around dense human settlements. This study will produce a profile of the Town’s current urban forest, also known as the tree canopy cover.

The study began in late July 2008. Both privately and municipally owned trees, including those on streets, in parks, and trees growing on commercial or private property, are included in the study.

Through a GPS mapping program, 200 plots were randomly selected across Ajax. Each plot has a radius of about 11 metres. Each day, TRCA forestry technicians arrive at a plot at approximately 7 a.m. By observing the plot, the forestry technicians classify tree species, and measure the tree height and crown width. Each tree survey takes about an hour and is an unobtrusive process without any disturbance to the property.

The Town has sent letters to private property owners located within the study areas, informing them about the program and requesting their permission to enter their property in order to conduct the study. The study will be completed by the fall of this year.

When TRCA establishes its findings, they will advise the Town on how our urban forest is functioning in its present state, how it can be built upon, and how it can be maintained in order to sustain it.

The Town will hold a public open house in November 2008 to report its findings, and gain resident’s insight and ideas about the proposed Urban Forestry Strategy. The final draft of the strategy will go to Council in December.

The Mighty Oak Tree

The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus, and some related genera, notably Cyclobalanopsis and Lithocarpus.

The genus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas. Oaks have spirally arranged leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin.

The flowers are catkins, produced in spring.

The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6-18 months to mature, depending on species.

Oaks are hardwood trees, and the wood is commonly used in furniture and flooring.

The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus, and some related genera, notably Cyclobalanopsis and Lithocarpus.

The genus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas. Oaks have spirally arranged leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin.

The flowers are catkins, produced in spring.

The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6-18 months to mature, depending on species.

Oaks are hardwood trees, and the wood is commonly used in furniture and flooring.

Dutchman Tree Spade 720

When looking to move larger trees with minimal effort, Dutchman’s 72-inch spades are a durable, light weight, and dependable tool. Dutchman’s 72-inch tree spades are designed to produce a ball 75-inches in diameter. The interior, low profile frame is designed with 2 gates and a lock. It is designed with the highest volume valve and blade components. 

Features

 
Digs from 74-inch down to 50-inch

Interior Design is large enough, and low enough to slide under and around low branches. Spade is produced in a 4-blade version

Weight: 5500 lbs.

Weight of machine and full ball: 10900 lbs.

More information on the Dutchman 720 Tree Spade »

The Value of Trees

Imagine a world without trees. It’s virtually impossible, because without trees we can’t survive. Trees are essential to life and yet, they are taken for granted. Unfortunately, one million acres of forest are lost to city growth each year.

Trees offer many benefits that are obscure to many, which include:

• Air Filtration- filters out particulate matter and absorbs harmful gases
• Purifies Water-improves water quality by slowing and filtering rain water
• Cost Reduction- provides shade and shelter, reducing yearly heating and cooling costs by 2.1 billion dollars
• Climate Control-obtained by moderating the effects of sun, wind, and rain
• Increase Property Value- well-cared landscape properties are 5-20% more valuable than non-landscaped estates
• Protection-from downward fall of rain, sleet, and hail, as well as reducing storm run-off, and the possibility of flooding
• Glare and Reflection Control
• Wind Break, Deflection, and Filtration
• Sound Barrier

Since trees are a growing asset to any property, maintenance of the trees is crucial for long-term health, safety, and aesthetic value. Many people do not realize that trees have a dollar value of their own. Competent tree appraisers can determine the dollar value of your trees and plants by evaluating the size, type (classification), condition, and location of the tree.

Moving trees with a Tree Spade

Tree spading is a common method for moving and transplanting large trees from one site to another. The following are some reasons for transplanting large trees vs. younger, smaller trees are:

• To prevent the loss of a tree due to building, roadway expansion or other construction;
• To create space for a new building addition;
• A particular mature tree has outgrown its present location;
• To alter the design of a landscape;
• To move a tree to a site better suited to its needs;
• To create a mature landscape quickly.

Initially, transplanting a tree with a tree spade may be more costly than purchasing container stock or B&B trees. However, the tree spade may be the best option if a tree will otherwise be lost or if the value of the tree outweighs the moving costs. Spading is also saves labor, planting time and years of maintenance of the juvenile tree. Spading also eliminates the possible risk of mower damage that commonly occurs on younger, smaller trees.

Tree spades are used in various ways throughout the green industry. Commercial nurseries use tree spades to lift large, field-grown trees out of the soil, and wrap the root ball in burlap and twine (termed “ball and burlap” or B&B) for retail sale or compact storage. Landscape companies and arborists use spades to plant large trees that are nursery-grown or have been moved from elsewhere in the landscape. Landscape professionals use a tree spade to create an “instant landscape” by digging and transplanting large trees from one location to another.

Homeowners can also use spades to locate trees on residential sites. Trailer-mounted spades that can hold a soil ball up to 44 inches in diameter are available at some rental centers. However, due to safety issues, and the complexity of the equipment and processes involved, it is strongly recommended that individuals hire an experienced contractor specializing in tree spading to transplant trees.

Always contact the proper company or municipality for the location of underground utilities prior to digging. It is also important that you locate private lines such as irrigation systems, wiring for landscape lighting, water lines that serve water fountains and ponds, etc.

Supplies and Specifications:

Tree spades are available in a variety of types and sizes. Some spades have the capacity to move a tree with a maximum trunk diameter of eight to 10 inches, or a soil ball up to 90 inches in diameter. The size of the spade is critical. It must be large enough to accommodate a root ball that will sufficiently sustain the tree after planting. If a spade is too small, the root system will be too small to allow for long term establishment and the tree will die. When determining the spade size needed to move a tree, deciduous trees are measured by trunk diameter and evergreens are measured by tree height. A tree spade can be used to move one tree at a time or a pod trailer may be used to move as many as three trees at one time.

Tree spade size	Deciduous tree - trunk diameter	Evergreen tree - height
44 inches	2 to 3 inches	5 to 7 feet
66 inches	3 to 5 inches	7 to 10 feet
92 inches	6 to 8 inches	12 to 15 feet
Trunk diameters are measured using a caliper, six inches above the ground for tree four inches in diameter or smaller and 12 inches above the ground for trees with a large diameter.

Fig. 1 Tree spades according to tree sizes

Many trees can be moved any time of the year using a tree spade, providing the ground is not frozen. Certain species such as firs, maples, and spruce are best transplanted during the cooler months of spring and early fall. Plants moved in the summer and fall should be dug with an oversized root ball with special attention paid to the species of the tree, its condition and how it is transported. Reducing water loss as much as possible is important during transportation. Trees should not be moved on hot, windy days. The foliage may also be sprayed with an anti-transpirant prior to transplanting to reduce water loss.

As a general rule, deciduous trees transplant well if moved early in the spring before they leaf out, or in the fall after the leaves have begun to turn color. Evergreen trees should not be moved during the flush of new growth in the spring or late in the fall when it is too late for the roots to become established before winter. There are exceptions. For example, birch trees should not be moved until buds break in the spring, and trees with tap roots are difficult to move successfully regardless of the season. Some trees, such as Mountain Ash, do not transplant well when they are large plants. In this case, it is best to purchase a new, juvenile plant from a reputable grower.

There are differences between moving nursery-raised trees and trees grown in the wild or as windbreaks. Trees grown in nurseries are easier to move because they have been subject to maintenance practices such as root pruning. Root pruning promotes the growth and development of the most viable roots, resulting in maximum health and minimal stress. Trees grown in the wild are often difficult to transplant because they have grown in an understory environment that protected them from the wind. The results are large, shallow root systems and weakened trunks. Trees grown as windbreaks may be transplanted more easily if they were originally transplanted as container or B&B plants early in life. However, these trees do not make good transplants as they often suffer from poor structure due to tight plant spacing and environmental stress as well as insect and disease issues.

Understanding the root system - taproot or fibrous - will help determine the transplant capabilities of the tree, the spade size required and the success of the transplant. As a general rule, trees with tap roots will not transplant well. Most root systems develop within the upper three feet of soil with a majority of the absorbing roots in the top 6 inches. After transplanting, critical root regeneration occurs from behind the cut ends of the roots which are located close to the edge of the plug.

Soil type plays an important role in transplant success. The soil structure - clay, sand, loam, etc. - influences the tree’s root extension and penetration. Roots typically extend past the crown of the tree. Clay soil will contribute to a smaller rootball while trees grown in sandy soil will have an extensive root system. Other soil factors include the level of soil compaction and moisture. Nursery-grown trees are subject to root pruning to promote fibrous root growth and thus have root systems that are denser, but typically not as extensive, as field-grown trees. Many native trees that have grown in the wild should not be transplanted to open, exposed locations. They may be structurally weak and have a shallow, spreading root system that extends well beyond the crown of the tree due to the fact they usually grow in a shaded, protected environment.

Design:

Proper placement of trees is important to the design and sustainability of the landscape. It is important to select a location where the tree will not grow to interfere with structures, power lines, snow removal, roof lines, windows and other existing plants. The species of tree selected for a site will depend on space requirements, existing plants and structures, seasonal interest desired and the function the tree will serve in the landscape. Some common functions of trees in the landscape are:

• Trees may be used to soften the architectural lines of a building and transition the eye from the roofline to the soil;
• Trees may be used in a design to create shade and reduce summer cooling costs;
• Trees may protect a building from winter winds and thus reduce heating costs;
• Trees may act as a backdrop to a landscape;
• Trees may provide screening or a ceiling over an outdoor space.

Site considerations:

• Individuals involved should have a general understanding of the tree spading process, and be familiar with the sites where the tree spade will be operated;
• There should be adequate access for the tree spade to the original site and the new site. Because the spade is in a fixed position, it is desirable to plan the move with access to the preferred side of the tree. Maintaining the same exposure is beneficial to tree establishment.
• Locate existing power lines, underground septic systems, grade changes and note any restrictions they present;
• There should be adequate space for the tree spade to operate safely. A 44-inch tree spade requires approximately six feet around the tree that is unobstructed. A 90-inch spade requires eight feet.
• Current soil conditions should be relatively dry. If the soil is too wet, the heavy machinery will damage the soil structure. Turf should be protected with 10-12 inches of wood mulch or ¾” plywood.

When transplanting a large tree, it is important to duplicate the original conditions as closely as possible, therefore reducing stress on the tree. Soil type, planting depth, staking, watering and mulching are critical factors to the success of the transplant.

Soil type:

If possible, the soil type of the new location should match the soil type, drainage and pH of the original site as closely as possible. For large projects with many trees to be moved and transplanted, a soil analysis is recommended to compare soil structure, porosity, and amendments required. Knowledge of theses factors may favor one source of trees over another. Using a tree spade may also cause glazing, the compaction of the soil in the newly-dug hole, which will affect the lateral movement of soil moisture and root penetration. This can be resolved by roughing up the sides of the hole and the plug using a shovel, rake or fork.

Planting depth:

The root ball of the tree should be watered thoroughly prior to digging to keep the ball intact and reduce as much soil loss as possible during transport. To allow the tree to become adequately hydrated, the tree should be watered 1-2 days prior to moving the tree. When positioning the tree in the new hole, it should be placed 2-3″ higher than the original grade to allow for settling. If a tree is planted to shallow, the roots may be damaged by temperature fluctuations and lack of soil moisture. Planting a tree too deeply will result in girdling problems later. For more information:

Staking:

An important function of the plant’s root system is to anchor the plant, reducing the chance for a blow-over or uprooting by excess water or erosion. However, the roots of newly transplanted trees will not establish themselves securely in the ground for several weeks after planting. Thus they may require extra support through staking. It is important to remove the staking as soon as the tree is well-rooted as trunk strength can be weakened by long term staking.

Watering:

Because newly planted trees do not have an extensive root system, it is important to deeply water transplants on a regular basis and especially throughout dry periods to reduce water stress. Prolonged water stress will cause a tree to become susceptible to insect damage and diseases, and cause limbing that greatly affects the tree aesthetics and value in the landscape. Likewise, overwatering or poorly drained soil may create an anaerobic environment (without air) around the root zone that is favorable to rot-causing fungi and bacteria, or may cause roots to suffocate.

It is important when watering newly transplanted trees that the original soil ball and surrounding soil is saturated to a depth of 12″. Apply water slowly to entire area, allowing adequate penetration. Another option is to create a dike with soil around the outside edge of the soil ball. This dike will retain water applied in high volume, and allow it to slowly saturate the soil without erosion. This method works well when trees are watered using a watering truck or tank trailer. Watering is normally required weekly for the first month and twice a month for the rest of the first growing season. Watering should continue as needed for 2-3 seasons after transplanting. It is critical that evergreens be watered regularly and thoroughly until the soil freezes in order to prevent winter browning and needle desiccation due to dehydration by winter winds and sun exposure.

Mulch:

Newly planted trees as well as new shrubs and established woody plants benefit significantly from mulching. Some of these benefits include:

• More uniform soil temperature
• Reduced soil erosion
• Reduced weed competition
• Improved moisture retention
• Reduced damage to tree trunks and roots from mowers, weed whips, etc.
• Provides an attractive finish to shaded areas underneath trees where grass grows.

After transplanting a tree, apply a 4-6″ layer of elongated wood mulch, shredded bark or other organic mulch around the base of the tree, pulling it away from the trunk to reduce damage from trapped moisture. The mulched area should ideally reach out 10-12″ past the original root ball. Trees with dikes around the edge of the mulch ring are ideal for retaining mulch through the first growing season. The dikes can be removed after the first season, creating a clean transition between mulch and turf.

Benefits of Trees

Most trees and shrubs in cities or communities are planted to provide beauty or shade. These are two excellent reasons for their use. Woody plants also serve many other purposes, and it often is helpful to consider these other functions when selecting a tree or shrub for the landscape. The benefits of trees can be grouped into social, communal, environmental, and economic categories.

Social Benefits

We like trees around us because they make life more pleasant. Most of us respond to the presence of trees beyond simply observing their beauty. We feel serene, peaceful, restful, and tranquil in a grove of trees. We are “at home” there. Hospital patients have been shown to recover from surgery more quickly when their hospital room offered a view of trees. The strong ties between people and trees are most evident in the resistance of community residents to removing trees to widen streets. Or we note the heroic efforts of individuals and organizations to save particularly large or historic trees in a community.

The stature, strength, and endurance of trees give them a cathedral-like quality. Because of their potential for long life, trees frequently are planted as living memorials. We often become personally attached to trees that we or those we love have planted.

Communal Benefits

Even though trees may be private property, their size often makes them part of the community as well. Because trees occupy considerable space, planning is required if both you and your neighbors are to benefit. With proper selection and maintenance, trees can enhance and function on one property without infringing on the rights and privileges of neighbors.

City trees often serve several architectural and engineering functions. They provide privacy, emphasize views, or screen out objectionable views. They reduce glare and reflection. They direct pedestrian traffic. They provide background to and soften, complement, or enhance architecture.

Environmental Benefits

Trees alter the environment in which we live by moderating climate, improving air quality, conserving water, and harboring wildlife. Climate control is obtained by moderating the effects of sun, wind, and rain. Radiant energy from the sun is absorbed or deflected by leaves on deciduous trees in the summer and is only filtered by branches of deciduous trees in winter. We are cooler when we stand in the shade of trees and are not exposed to direct sunlight. In winter, we value the sun’s radiant energy. Therefore, we should plant only small or deciduous trees on the south side of homes.

Wind speed and direction can be affected by trees. The more compact the foliage on the tree or group of trees, the greater the influence of the windbreak. The downward fall of rain, sleet, and hail is initially absorbed or deflected by trees, which provides some protection for people, pets, and buildings. Trees intercept water, store some of it, and reduce storm runoff and the possibility of flooding.

Dew and frost are less common under trees because less radiant energy is released from the soil in those areas at night.

Temperature in the vicinity of trees is cooler than that away from trees. The larger the tree, the greater the cooling. By using trees in the cities, we are able to moderate the heat-island effect caused by pavement and buildings in commercial areas.

Air quality can be improved through the use of trees, shrubs, and turf. Leaves filter the air we breathe by removing dust and other particulates. Rain then washes the pollutants to the ground. Leaves absorb carbon dioxide from the air to form carbohydrates that are used in the plant’s structure and function. In this process, leaves also absorb other air pollutants—such as ozone, carbon monoxide, and sulfur dioxide—and give off oxygen.

By planting trees and shrubs, we return to a more natural, less artificial environment. Birds and other wildlife are attracted to the area. The natural cycles of plant growth, reproduction, and decomposition are again present, both above and below ground. Natural harmony is restored to the urban environment.

Economic Benefits

Individual trees and shrubs have value, but the variability of species, size, condition, and function makes determining their economic value difficult. The economic benefits of trees can be both direct and indirect. Direct economic benefits are usually associated with energy costs. Air-conditioning costs are lower in a tree-shaded home. Heating costs are reduced when a home has a windbreak. Trees increase in value from the time they are planted until they mature. Trees are a wise investment of funds because landscaped homes are more valuable than nonlandscaped homes. The savings in energy costs and the increase in property value directly benefit each home owner.

The indirect economic benefits of trees are even greater. These benefits are available to the community or region. Lowered electricity bills are paid by customers when power companies are able to use less water in their cooling towers, build fewer new facilities to meet peak demands, use reduced amounts of fossil fuel in their furnaces, and use fewer measures to control air pollution. Communities also can save money if fewer facilities must be built to control storm water in the region. To the individual, these savings are small, but to the community, reductions in these expenses are often in the thousands of dollars.

Trees Require an Investment

Trees provide numerous aesthetic and economic benefits but also incur some costs. You need to be aware that an investment is required for your trees to provide the benefits that you desire. The biggest cost of trees and shrubs occurs when they are purchased and planted. Initial care almost always includes some watering. Leaf, branch, and whole tree removal and disposal can be expensive.

To function well in the landscape, trees require maintenance. Much can be done by the informed home owner. Corrective pruning and mulching gives trees a good start. Shade trees, however, quickly grow to a size that may require the services of a professional arborist. Arborists have the knowledge and equipment needed to prune, spray, fertilize, and otherwise maintain a large tree. Your garden center owner, university extension agent, community forester, or consulting arborist can answer questions about tree maintenance, suggest treatments, or recommend qualified arborists.

Record-setting Trees

• One of the tallest soft wood trees is the General Sherman, a giant redwood sequoia of California. General Sherman is about 275 ft or 84 m high with a girth of 25 ft or 8 m.
• The 236 ft or 72 m high Ada Tree of Australia has a 50 ft or 15.4 m girth and a root system that takes up more than an acre.
• The world’s tallest tree is a coast redwood in California, measuring more than 360 ft or 110 m.
• The world’s oldest trees are 4,600 year old Bristlecone pines in the USA.

Trees and Science

• Dendrochronology is the science of calculating a tree’s age by its rings.
• Tree rings provide precise information about environmental events, including volcanic eruptions.
• A mature birch tree can produce up to 1 million seeds per year.
• Moon trees were grown from seeds taken to the moon by Stuart Roosa, Command Module pilot of the Apollo 14 mission of January 31, 1971. The effort included 400-500 seeds, which orbited the moon on the first few days of February 1971. NASA and the USFS wanted to see if being in space and in the moon’s orbit would cause the seeds to grow differently than other seeds.

Trees and the Environment

Tree Facts

• Trees renew our air supply by absorbing carbon dioxide and producing oxygen.
• The amount of oxygen produced by an acre of trees per year equals the amount consumed by 18 people annually. One tree produces nearly 260 pounds of oxygen each year.
• One acre of trees removes up to 2.6 tons of carbon dioxide each year.
• Shade trees can make buildings up to 20 degrees cooler in the summer.
• Trees lower air temperature by evaporating water in their leaves.
• Tree roots stabilize soil and prevent erosion.
• Trees improve water quality by slowing and filtering rain water, as well as protecting aquifers and watersheds.
• The cottonwood tree seed is the seed that stays in flight the longest. The tiny seed is surrounded by ultra-light, white fluff hairs that can carry it on the air for several days.

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