Developmental Perspectives of Protective Windbreaks -Dec. 2013

UNITED ARAB EMIRATES

EMIRATE OF ABU DHABI

Developmental Perspectives of Protective Forest Windbreaks

for Cities and Highways in Abu Dhabi Emirate

Dr. Abdul Sattar Salih Al-Mashhadani

Landscape Expert

Parks and Recreation Facilities Division

Infrastructure and Municipal Assets Sector

Developmental Perspectives of Protective Forest Windbreak

Al Mashhadani A.S., PRFD, ADM, DMA, Abu Dhabi, UAE (29-12-2013 ) Page 1

Table of Contents

Introduction ............................................................................................................................................................... 2

Importance of windbreaks ..................................................................................................................................... 3

General Benefits ....................................................................................................................................................... 3

Definition of shelterbelts ....................................................................................................................................... 5

Forest shelterbelt designs ...................................................................................................................................... 6

The effect of winbreaks and shelterbelts on wind .......................................................................................... 8

Windbreak Distribution Layout ......................................................................................................................... 11

Rules and requirements of the establishment of windbreaks and shelterbelts ..................................... 15

Select the plant species for shelterbelts composition ................................................................................. 16

The local experience of Forest Shelterbelts .................................................................................................. 18

The main reasons leading to the deterioration of shleterbelts in certain locations ............................. 18

General obstacles to agricultural operations .................................................................................................. 20

Development and improvement of greening activities ............................................................................... 21

Median landscaping .............................................................................................................................................. 21

Consequences of failure to take measures for the maintenance of medians ......................................... 24

General recommendations and suggestions .................................................................................................. 25

Future vision .......................................................................................................................................................... 26

Conclusion ............................................................................................................................................................... 27

References ................................................................................................................................................................ 27



Developmental Perspectives of Protective Forest Windbreaks

for Cities and Highways in Abu Dhabi Emirate

Introduction

The UAE’s pioneering work in the fields of agriculture and forestry has received

attention from several regional and international organizations. It is considered one of the

unique experiments in the region, having succeeded in an area dominated by a lot of

harsh environmental conditions which are unsuitable for plant growth. Despite all of

these circumstances, the Emirati people have gone through this experience and emerged

successful thanks to the unlimited support given by the late His Highness Sheikh Zayed

bin Sultan Al-Nahyan and his wise leadership across all sectors concerned, including the

municipal sector. In addition, the high principles lay down and adopted by His Highness

Sheikh Khalifa bin Zayed Al-Nahyan represent the right approach for people and

governments alike to dealing with the environment in the United Arab Emirates.

The achievements made in the field of agriculture and forestry are a direct result of the

great efforts of Abu Dhabi Municipality delivered mainly through the departments

concerned with agriculture, forestry and agricultural extension, with support from other

relevant departments inside and outside the Municipality.

These projects have prompted several major technical works, particularly those related to

earth-moving, in addition to drilling wells, laying pipes, constructing tanks and irrigation



networks, and other necessary measures to prepare for the critical stage of agricultural

and forestry works, as well as for subsequent engineering works which took into account

the aesthetic aspect and conforming with the characteristic nature of the place.

Importance of windbreaks

The use of shelterbelts and windbreaks has become widespread in many parts of the

world after their positive impacts on improving microclimatic conditions and their

protective functions against the immediate negative impact of prevailing winds have

become known to people. Such positive effects include reducing evapo-transpiration,

erosion, corrosion, soil drifting those impacts particularly on agricultural production as

well as the quality and quantity of the positive impacts on public health and safety on the

roads and industrial areas.

For this great importance, and in all parts of the world, we find that many governmental

and civil organizations have sought to establish windbreaks and conduct a lot of different

studies and experiments on them to determine the extent of their positive impact on

various environmental factors and benefits as a result of this impact through the

development of windbreak design and the variety of types for each region with the aim of

proper exploitation of land and the development of natural resources in different regions.

General Benefits

The overall impact of these shelterbelts is the improvement of micro-environmental

conditions in the areas protected by them, the protection of main roads from the effects of

sandstorms and sand accumulations, effective soil stabilization and minimization of wind

erosion. In addition, the large number of trees and shrubs contribute to providing lands

with soil nutrients and increase the amount of humus in soil. Therefore, they are

considered the self-nutrient which provides natural organic fertilizers in addition to the

aesthetic appeal they impart to the areas in which they grow, thereby indirectly

supporting the country’s tourism industry. The ultimate outcome of all the above can be

an increase in the social welfare and support of the national economy.

Overall, their benefits on the local scale can be summarized in the following points:

They are one of the most important biological soil improvement methods used for

stabilizing sand and sand dunes, stopping their drifting, and combating erosion.

They provide protection for external roads and the various means of transport

from the effects of strong and hot sand storms, and reducing their negative effects



on public safety, especially reducing sand accumulations and facilitating sound

and safe vision.

They provide protection of agricultural crops (fields), livestock, pastures, and the

various civilian and service installations (around cities, residential areas, water

tanks, etc.) from the effects of cold winds, dry winds, simoom and sandstorms,

thereby providing the right atmosphere to ensure good production and

performance both quantitatively and qualitatively.

They are considered as protective biotic cover for all national defense installations

and stations.

They provide protection and shade for humans and wildlife in general, and

contribute to their development and prosperity.

They improve the aesthetic appeal of the areas [in which they are cultivated],

which helps attract tourists and support the country’s tourism industry.

They are considered a source of such by-products as organic materials, feed,

pharmaceuticals, etc., and are used for beekeeping…etc.

They provide a safe environment in which many native plant species can be

successfully grown, by virtue of their positive impact on changing micro-

environmental conditions in favor of the species most sensitive to the harsh local

conditions.

They are considered as mega-projects which contribute to attracting a large and

diverse workforce. They are also investments of future value for the protected

areas.

In view of their great importance, they are considered a component of the biosphere

which plays an important role in combating desertification, conserving nature, and

boosting tourism.



Definition of shelterbelts

Protective shelterbelts are a group of forest woody plants (trees and shrubs) planted in

one or more longitudinal strips or live hedges. They consist of 3-5 rows spaced 3-4

meters apart and in the same row they are spaced 2-3 meters apart. Shelterbelts either

consist of one main species or a mix of species more tolerant and resistant to the regional

conditions.

The direction of shelterbelts lines depends on the land topography. On flat areas, they are

established at right angles to the direction of the prevailing and more effective winds.



However, in wavy areas and sloping terrain with a slope of over 1.5-2, the direction of

shelterbelts should be perpendicular to the direction of the slope. It should be taken into

account that shelterbelts provide the most protection when winds blow perpendicularly to

evergreen trees or to deciduous trees when they are in leaf. In certain cases, shelterbelts

can be distributed based on the amount of wind damage and at an angle not exceeding

30°, as shown in Diagram 1.

Forest shelterbelt designs

Shelterbelts and windbreaks are barriers used to reduce wind speed and change its

direction. They are established in flat lands for purposes of protection from the effects of

unfavorable environmental factors. They represent one of the several groups of forest

plants with diverse designs which differ in their wind permeability.

The following are the main windbreak types:

1- Permeable windbreaks:

Permeable windbreaks consist of a minimum of 1-3 rows with the trees spaced 4 meters

apart. They are used for landscaping, timber production, internal road afforestation, and

protecting waterways and tourist areas.



2- Semi-permeable windbreaks:

Semi-permeable windbreaks consist of a minimum of 1-3 rows with the trees spaced 2

meters apart. They are used for the same purposes mentioned above, but they also act as

barriers against wind, sand and dust storms.

3- Impermeable windbreaks:

Impermeable windbreaks consist of a minimum of 3-5 rows, and up to 100 rows, with the

trees spaced 1 meter apart. They are used in dry areas with severe sand and dust storms.

There are several sub-designs derived from of the above main designs.

In general, 3-meter spacing between rows and 2-meter spacing between trees are

considered ideal for windbreaks used for protecting roads and fields. So, we can say that

semi-permeable windbreaks are one of the best types of windbreaks used for these

purposes.

Shelterbelt design means planting woody plants so that the longitudinal section of the

shelterbelt has a specified degree of wind permeability. This degree is measured by the

space between the trees and shrubs within the windbreak. It depends on the type of design

which is determined by the conditions in the area, the type of plants selected (species

composition), their layers (within the longitudinal section) and spacing (plant density),

the height and width of the windbreak or shelterbelt, etc. Windbreak permeability is the

main factor determining the effectiveness of shelterbelts or windbreaks (see the table

below).

General description of the main forest shelterbelt designs

Main forest

shelterbelt designs

Longitudinal section of the shelterbelt in leaf

Distribution and

prevalence of gaps

Percentage of permeable openings

%

Between trunks In canopies

Impermeable Almost free of gaps <10 <10

Semi-permeable Small gaps almost over the

whole section of the belt 15-35 15-35

Permeable

Large gaps between the

trunks and almost without

gaps in the canopies

>60 <15



The design type is assessed according to the area’s environmental characteristics and its

adaptive species. Windbreaks and shelterbelts serve various purposes. Some of them are

used for the protection of cities; highways; industrial areas; sides of the main roads;

approaches to valleys and canyons; and areas around marshes, sand dunes and water

tanks. Others are used for regulating water movement, protecting soil from erosion,

protecting fields, pastures, barns...etc.

The effect of windbreaks and shelterbelts on wind-system

The important and effective role of windbreaks is ascribed to their special impact on wind

system, reduction of the sand accumulation carried by the wind, and consequently their

positive impact on changing the microclimate in the protected areas. Wind system

determines the sand distribution and its transport and dispersion, some of which gets

blocked by the windbreak and its ends in the form of soil barricades. The decreased wind

that faced the biomass of windbreak or shelterbelt can be divided into two parts, one of

which rises above the windbreak and the other goes through it. As wind moves away

from the windbreak, it regains its speed.

The effect extend of protective windbreak that located on the leeward side varies

according to the windbreak or shelterbelt structure, height, density, number of

rows, species composition, length, orientation, and continuity, all of which

contribute to determining its effectiveness in reducing wind speed and positively

changing the microclimate of protected.

Effect of height

The shelterbelt height (H) is the most important factor in determining the protected area.

On the leeward side of an impermeable windbreak, wind speed reductions are measurable

for a distance of 15 to 20 times the height of the windbreak (15-20H). This distance can

often decrease to 10-15 times (10-15H). On the windward side, however, the distance of

wind speed reductions is up to 10 times the height of the windbreak (10H), which does

not exceed 25% of the wind speed (Diagram 2). Semi-permeable windbreaks are

generally considered among the best windbreaks because they reduce the effect of wind

for a significant distance of 30H on the protected leeward side and allow the passage of

reasonable amounts of wind, as they reduce its speed by 50-55% on average within the

protected area. Therefore, semi-permeable windbreaks are recommended for the

protection of roads and fields prone to sandstorms and dry winds. In contrast,

impermeable or closed windbreaks (which have no openings in their longitudinal sections



– almost 10%) can create eddies within the protected area as a result of the great pressure

difference directly behind the windbreak. The effective height (H) in multiple-lines

windbreaks is the tallest tree-line that determines their value.

The Effect of Density

Windbreak density is the ratio of the foliage (solid) portion of the windbreak to the total

area of the windbreak. Wind flows through the open gaps of a windbreak, thus the more

vegetation in windbreak section, the less wind passes through. The high-density

windbreaks develop low pressure areas on the leeward side. This low pressure area

behind the windbreak pulls air coming over the windbreak downward, creating eddies

and reducing windbreak effectiveness and the length of the protected area. As density

decreases, the amount of air passing through the windbreak increases, moderating the low

pressure and turbulence, and increasing the length of the protected area.

Therefore, by adjusting windbreak density, different wind flow patterns and areas of

protection are established.

As general, the windbreak density of 40-60% percent provides the greatest area of

protection and provides excellent soil erosion control as well as an optimal distribution of

their dispersion outputs. On the other hand a density of 25-35% affects a larger area, but

may not provide sufficient control of soil erosion.



Farmsteads and livestock areas that need of protection against the impacts of dry summer

winds and cold winter winds may require multiple-row windbreaks with high densities.

Such windbreaks provide greater wind speed reductions, but their protected areas are

smaller (2H-5H).

Multiple-leg windbreaks are recommended in areas with variable-direction prevailing

winds to increase the area of the protected zone (see figure below).

The number of rows, the distance between trees, and species composition are all factors

controlling windbreak density. The interaction of height and density determines the

degree of wind speed reduction, and ultimately the length of the protected area.

For a given height, the protected area usually increases as density increases. However, if

density is below 20%, the windbreak does not provide useful wind reduction. Similarly, if

density is above 80%, an excessive leeward turbulence may reduce windbreak

effectiveness.

The use of multiple-leg windbreaks

(Provides a larger protected area than a single windbreak)



Windbreak Distribution Layout

Determination of the adopted design and the expected windbreak effectiveness, in light of

the outcome of all the data and rules for establishment, could lead to the initialization and

setup of the following steps:

1- Preparation of forest shelterbelt plantation site:

The preparation of the appropriate site is the optimal measure to improve the survival

percentage of the selected woody species of which the shelterbelt is composed.

In flat areas, the shelterbelt location is determined based on the direction and speed of the

prevailing and most damaging winds in the area, so that the road to be protected (for

example) lies within the boundaries of the protected zone. The protected zone area is

estimated based on the height of the main species, reached on its maturity stage, taking

into account the change in the topography of some of the sites along the road (sloping or

drifting sites …).

The extent of the protected area by shelterbelts is greatly affected by the site’s

environmental conditions and the type of soil. Less favorable climatic and soil



conditions means less extensive area, and vice versa, because healthy tree growth

(increases the height) means an increase in the extent of the protected area.

2- Determination of the width windbreak and the number of its lines, and strips:

This is largely depends on the type of design, wind speed and land topography, where

the wind speed generally decreases with increasing the rows of the shelterbelt.

The windbreak width determines the number of rows of woody plants, which are usually

three, four, or five.

3- Determination of plant spacing: plant spacing is determined in the light of the

outcome of interaction between the type of design and the local environmental

conditions of the area, especially wind and topography (see diagrams 1, 2, 3-3, 4, 5).



Controls and requirements of the windbreaks establishment

It is necessary, before proceeding with establishment of windbreaks, to take into account

their rules and provide the necessary requirements. Such requirements can be

summarized as follows:

Data on the area’s environmental conditions, especially its topographical and

climatic features, detailed information about wind dynamics, and the type and

speed of prevailing sand storms in the area (according to the local Wind Rose).

The area’s land use and classification scheme, priority of shelterbelt establishment

should be given more critical sites in coordination with the relevant authorities.

Data about the quantity and quality of water sources.

A consolidated list of plant species in the area or species composition across the

areas based on a study of the native and exotic plants in the area which proved to

be successful and suitable for cultivation in windbreaks in the light of their

general characteristics.

It is necessary to take into account the appropriate design, number of rows, and

appropriate spacing between rows and between the trees in each row.

When establishment the forest shelterbelts, taken into account their proper

distribution to achieve the functional purposes according to the prepared plan for

each type.

Proper choice and mixing of the species composition will determine the cross-

sectional shape of the windbreak (Diagram 6). The following are the best

windbreaks:

– Windbreaks of a pyramidal cross-section with inclined sides, which consist of

high to low trees and shrubs arranged in an odd number of more than two

rows.

– Windbreaks of a parallelogrammic cross-section which consist of an even

number of more than two rows.

Provision of all the technical resources such as agricultural machinery, heavy

equipment, tools, and other resources required for shelterbelt establishment.

Assignment of tasks to specialists, depending on their nature, taking into account

that the number of staff should match the volume of work.

Continued maintenance (especially during the first 3-4 years) to help improve

their growth and survival percentage to achieve the desired protection.



Preparation of wall charts showing windbreak or shelterbelt data including their

designs, species composition, plant and row spacing, stripe width, and prevailing

wind direction.

Select the plant species for shelterbelts composition In order for shelterbelts to be

more effective in achieving their purpose, their constituent tree and shrub species should

be properly chosen, taking into consideration their genetic features, site conditions, type

of soil, the level and quality of groundwater, sufficiency and quality of irrigation water,

the purpose for which they are planted and their characteristics, in addition to the impact

of social and economic factors. For example, thorny species are planted near urban areas

and animal paths, while fodder species can be a good choice in areas where fodder is in

short supply (provided that they are properly managed), or species with good wood… etc.



Key features of the species selected for shelterbelts:

1- Strong, free from and resistant to pathogenic micro-organisms and insects.

2- Resistant and adaptive to the area’s environmental conditions (climatic: high

temperatures, drought, wind, humidity, severe sunlight; soil: poor soil and salinity

… etc.)

3- Flexible, resistant to wind, with straight stems, uniform crowns, and large

developed root systems with deep extensions to resist wind pressure.

4- Fast-growing species that yield good timber.

5- Among the species that are not harmful to animals and, at the same time, resistant

to animal damage.

Overall, based on the considerations of the local conditions of the targeted area, some

species can be recommended for cultivation in the shelterbelts protecting roads, farms,

and fields. Such species are characterized by their ability to tolerate conditions of very

low soil moisture and their highly developed root systems.

It is preferred to use a mix of species, provided that the main species is not planted in the

first row facing the prevailing winds. It also is advisable to select species tolerant to

conditions of areas with high groundwater level and salinity, and salty irrigation water, in

which case an irrigation water drainage system must be installed.

To ensure windbreak effectiveness, scheduling of their maintenance and care should be

started directly after their establishment. This includes irrigation, hoeing, replanting

(immediately after the survival percentage is calculated), and caring to give the



windbreak the desired shape as needed and within the action plan (by approving the

pruning and thinning of the species that require such operations). The preferred species

here are the ones which do not require spending a lot of effort and money on such

operations. This is in addition to the need to protect their maintenance and conservation

operations against the impacts of fire, cutting, and grazing, by using fences or guards and

educating local communities about their importance and benefits, as well as securing

prevention and control operations when necessary.

The local experience of Forest Shelterbelts The protective forest shelterbelts have been

established in the United Arab Emirates, especially in sandy areas, in order to minimize

the effects of wind and sand storms, stabilize sand dunes and stop their drifting towards

cities, protect farms and external roads, combat desertification, and create a healthy and

more productive environment. Abu Dhabi Emirate has made great strides in the

cultivation of shelterbelts and windbreaks which cover an area more than 250000

hectares.

These areas can be classified as follows:

1- Shelterbelts protecting urban areas.

2- Windbreaks protecting fields and farms.

3- Shelterbelts and windbreaks protecting pastures.

4- Windbreaks protecting gardens, parks, nurseries, and orchards.

5- Windbreaks along main roads.

Shelterbelts are mostly planted at distances of 7×7 m in order to facilitate the various

servicing machinery and maintenance operations. However, shelterbelts around towns

and fields are planted at shorter distances to ensure highest effectiveness. Their success

depends on proper establishment and maintenance, especially during the first years after

cultivation.

The main reasons leading to the shelterbelts deterioration

The deterioration and slow growth of plants in certain locations can be attributed to a

number of reasons and practices, in addition to the harsh environmental conditions of the

area, the most important of which are summarized as follows:

(a) Natural reasons: Harsh environmental conditions (Climatic and location: Poor

soils; the level of salty groundwater, particularly in coastal areas; and the low quality

and quantity of the well’s water for irrigation).



(b) humanitarian reasons:

1- Lack of an effective water drainage system, particularly in areas with a high level

of salty groundwater, in addition to the contribution of an excess of water

irrigation along the sides and in the median of the highways in increasing the level

of salty groundwater. This case increases the area of marshes which may, in some

areas, reach vegetative sites, destroying them completely and irreversibly (that is

why proper planning for planting of such sites should be preceded by a study of

their characteristics).

2- Irregularity of irrigation networks means poor distribution of water over planted

areas, which leads to the emergence of significant water waste in some locations

and water recession in other locations (moisture deficit). Both situations have a

major impact on slowing the growth of plants and dying them. This is in addition

to the impact of irregular water supply.

3- Improper choice of the site or appropriate design.

4- Failure to choice the tolerant species that can resist conditions of the site, or the

wrong method of initial planting either because of failure to identify its priorities

or expediting the process to completion at the expense of quality and survival

percentage, thereby increasing the costs of replanting (replacement of dead

seedlings or dwarfed trees, after several years, with new seedlings).

5- A mismatch between the manpower, their skill level and the work size, that

assigned to each site and to various agricultural operations. This leads to the

adoption of worker transfers, which makes workers unavailable for conducting

periodic maintenance operations in a timely manner, causing obstruction of plant

growth and weakening their resistance.



Encountered obstacles to the development of agricultural operations

The agricultural operations in all parts of the world, even successful ones, are faced with

many problems and obstacles.

The most serious local problems facing agricultural operations, besides the impacts of

harsh environmental and soil conditions, are as follows:

1- The quantity and quality of irrigation water: Plant water requirement are generally

affected by the following factors:

(a) Quality and productivity of the water source.

(b) Irrigation network design.

(c) Land topography.

(d) Irrigation season.

(e) Lack of detailed studies on the calculation of water consumption based on plant

needs and soil type.

2- The high groundwater level in some areas and its impact on increasing the area of

marshes, and the need for a modern drainage system to solve this problem.

Interaction between all of the above factors, in addition to others related to the lack of

organic content and the main nutrient minerals in the soil (nitrogen, phosphorus, and

potassium), as well as the secondary … with the problems of soil salinization and

solidification, the inaccurate selection of the appropriate seedlings for planting as a result

for several reasons that are not the subject of study here; all these factors obstruct the

growth of species and make them vulnerable to pathogens and pests, which,

unfortunately, leads to the extensive use of various pesticides.

In order to eliminate or reduce the impact of these problems on the cultivation process,

the Municipality has undertook to adopt many research projects and activities and create

opportunities for cooperation with several regional and international research centers and

organizations.

In spite of the many impediments that faced the UAE’s pioneering experience in the

establishment of various forest stands, shelterbelts and windbreaks in and around cities,

along the sides of external roads, and around fields and farms under the harsh conditions

of the local environment (in addition to public gardens and parks); the sure indicator of

success is its contribution to reviving these sites and providing them with new

environmental components more suited to human life and activity as well as the lives of

the various living organisms, and the creation of appropriate conditions for many of the



subsequent activities. In addition, shelterbelts and windbreaks have the potential to be a

source of many raw materials for technological and medicinal uses, and fodder, as well as

a source of timber in the future if they are well managed as one of the most important

renewable sources.

Development and improvement of greening operations

Despite all the achievements, the Municipality aspires to achieve further excellent

performance through the adoption and application of scientific steps and standard

measures in all agricultural operations. To achieve this goal, attention should be paid to

the following measures:

1- Reshaping the green areas in Abu Dhabi city, based on new strategic plans, programs

and aesthetic standards.

2- Studying forest stands areas across the emirate of Abu Dhabi, through the following:

(a) Classification of forest plantations according to the priorities associated with

environmental importance and economic feasibility.

(b) Application of the proper rules for the establishment of the various forest stands,

shelterbelts, and windbreaks.

3- Extending afforestation plans beyond Abu Dhabi Island.

4- Development of plans and programs to promote the role of parks and various forest

plantations in conserving the environment.

Therefore, this study was conducted to highlight the importance of these shelterbelts and

windbreaks, their designs, rules for establishment, and the measures necessary for their

rehabilitation.

Median landscaping

Measures for the rehabilitation of road median landscape

1- Removal of all the trees and shrubs planted on the approaches to turns and U-

turns for a distance not less than 500-600 m. Subject to availability of the

appropriate conditions, such approaches can be planted with the adaptive or native

groundcover that can tolerate external road conditions.



2- Removal of trees planted adjacent to the vehicular lane because of their negative

impact on its safety (water seepage, root system growth).

3- Some dense rows need thinning, deteriorating shrubs need removing, and good

ones need transferring to other required nearby locations.

4- Pruning lower branches of the entire median trees, at a minimum height of 1 – 1.5

m from the surface level of flattened soil.



5- Pruning upper branches of the trees and thinning the lateral growth of their

crowns so they do not extend beyond the edges of the median at a distance not

less than 0.5 m from both sides.

6- Planting the remaining areas on the windward side of the road, where burial and

flattening operations have been conducted according to the rules.

7- Rehabilitation the water drainage into aggregated pathways to prevent any

damage to the lands adjacent to windbreaks or shelterbelts.

8- In a location of low water quality and quantity, depending on its importance, we

can avoid planting in the medians and merely plant the windbreak on the

windward according the rules and proper steps of their cultivation.

9- Nominate a specialized and qualified member from the Public Parks Department

to work as a permanent liaison member on the committee of the road construction,

with a view to developing designs for landscaping operations which take into

account the restrictions related to safety of the road and its various structures, in

addition to the effect of the future outlook for different land uses.

10- Reconsideration, according to general field inventory, the assessment of

windbreak plantations along road sides (which, in turn, requires an assessment of



certain low-level sites by the relevant entity) and medians, based on all the data

that have been identified in this study.

Consequences of failure to take measures for the maintenance of medians

Higher probability of traffic accidents in turns and U-turns due to lack of the necessary

distance for proper visibility of the other side of the road.

1- Higher probability of traffic accidents resulting from the accumulation of sand

along the interior part of the road adjacent to the median because of failure to trim

the bottom branches of the trees, thus providing the right conditions for the

creation of a low-pressure area on the windward side and leading to the deposition

and accumulation of sand, impediment of vehicle movement, and accidents.

2- In some external sites and within western cities, vehicles are forced to use the

right side of the road as a result of failure to trim and prune lateral branches of

tree crowns in the medians. This situation, besides causing traffic hazards,

constitutes an added load on that side of the road, which increases and multiplies

maintenance expenses and shortens the road's life span.



3- Some sites on the windward side, where earth filling has previously been

performed, constitute an additional source of sand that can accumulate on the

inner side of the road, especially medians with unmaintained vegetation.

General recommendations and suggestions

In conclusion, we believe that it is necessary to work in collaboration with the relevant

authorities to achieve the following:

Studying the environmental and biotic importance of windbreaks and shelterbelts

in the protection of main roads and cities

When recognizing the need to establish a windbreak or shelterbelt in a certain

area, controls and requirements should be taken into full account to ensure its

success and to achieve the desired goals.

Revival and enhancement of the growth of natural vegetation in the area,

especially the sites located near to the road intended to be protected, while

focusing on the windward side.

The establishment of a specialized central nursery should be considered early for

growing the required tolerant forest species, as well as native drought-resistant

plant species, to be used in afforestation and sand dune stabilization.

Serious steps should be taken towards undertaking an environmental impact

assessment and preparing scientific and applied plans to limit the increase in the

area of Sabkha as a result of the lack of irrigation water drainage systems along



windbreaks. An integrated plan should be developed, targeting mainly the

development of a modern and sophisticated network for water drainage in the

most critical areas.

Given the importance of shelterbelts and windbreaks, we believe that it is

necessary to develop a systematic program to manage them properly in a way that

leads to their nourishment and achieve their goals.

Future vision

Forest shelterbelts are generally mega-projects whose by-products can be of high value,

in addition to their priceless vital and moral influence, if properly utilized. As I have

already mentioned, they attract a large workforce, besides being tourist attractions. All

these and other important elements point to the possibility of achieving part of the self-

financing of such vegetation covers. To enhance the returns, we believe that it is

necessary to think of and encourage the cultivation of native and tolerant forest species

that have proved successful under the local conditions and that can provide fodder such

as Zizphus sp., Acacia sp. and Salvadora persica. Added to that is the possibility of

exploiting the lands of shelterbelts for the cultivation of herbaceous perennial and

herbaceous annuals and biennials species of medicinal and fodder value that are tolerant

to environmental conditions. A study could be performed in the near future of the

possibility of developing an integrated program to exploit the secondary outputs of

shelterbelts and the possibility of investing their resources in future expansion operations.

Future efforts to make the experience of growing shelterbelts a success, and the

dissemination of its outcomes and applications all over the country, will breathe life in

our land and enhance fertility and biodiversity, in addition to being a unique experience

in the region.

The final outcomes mean more suitability of our local environmental conditions,

enrichment of soil fertility, and activate its benefits on behalf of human

welfare and progress



Conclusion

Windbreaks and shelterbelts are biological assets, essential to all urban installations

(cities, factories, streets, fields and pastures … and many others) vital for meeting the

requirements of humans and his various activities. All windbreaks and shelterbelts,

whatever their types and designs, need regular maintenance from the first day of their

establishment. Such maintenance generally includes:

Regular care and maintenance, and proper pruning according to the type of

design.

Integrated Pest control to combat diseases that can infect the windbreak.

Immediate replanting (patching) where necessary.

Correct use of chemical materials at the sites and fields near the windbreak, to

support its effectiveness for many years.

References

– Al-Mashhadani A.S.1998. "Forests protect the fields". Environmental page, Al-

khaleej J., No.7121, UAE.

– Al-Mashhadani A.S.2000. An interview "Scientific aspects in forest

shelterbelts planting". Al-Asimma Magazine, No.53, Page 86-91, Abu Dhabi

Municipality, UAE.

– Al-Mashhadani A.S.2000."Establishing Forest Shelterbelts enrich the

Environment". Environmental page, Al- khaleej J., No.7646, UAE.

– Al-Mashhadani A.S.2001."The optimum way to protect the stands in our

environment". Al-Asimma Magazine, No.65-2001, page36, Abu Dhabi

Municipality, UAE.

– Al-Mashhadani A.S.2005 .“ The Forest-Shelterbelts … Its Construction &

Importance” Al-Murshid Magazine, No.27, Abu Dhabi Municipality, UAE.

– Belov S.V. 1983.Silviculture,M.”Forest Industry”, USSR.

– Kuhns, M. 1998. “Windbreak benefits and design” Cooperative Extension

Work, Utah State Univ., Logan, Utah, USA.

– Mattees G.Y. and et al. 1984.Guide of Agro-forestry amelioration, M. “Forest

Industry” , USSR.

– Novaseltseva A.I. and N.A.Smernov, 1983. Guide of Forest Nursery, M.

”Forest Industry”, USSR.

– Novaseltseva A.I. and A.R. Rodin, 1984. Guide of Forest Cultivation, M.

”Forest Industry”, USSR.

– Redeco G.I., A.R.Rodin and Treshavski I.V.1985. Forest Cultivation,

Textbook, M., USSR.



Appendix: A list of the most important plant species that can be cultivated on the

sides of external roads in the Emirate of Abu Dhabi

No. Scientific Name Family Name Arabic Name

*1 Acacia Arabica

Acacia nilotica Mimosaceae )السٌظ العربي )القرط

*2 Acacia cyanophylla Mimosaceae سيا ًىفيال

3 Acacia decurens Mimosaceae السٌظ األخضر

4 Acacia farnesiana Mimosaceae )السٌظ الحلى )الفتٌة

*5 Acacia syal Mimosaceae الطلح

*6 Acacia tortilis Mimosaceae )السٌظ الشائل )السور

7 Achras zapota

Manilkara zapotilla Sapotaceae )الجينى )السبىتا

*8 Atriplex litiformis Chenopodiaceae اتربلنس

9 bougainvillea spp. Nyctaginaceae جهٌوية

*11 Calligonum comosum Polygonaceae األرطا

*11 Casuarina equistifolia Casuarinaceae ٌاالنازواري

12 Clerodendrum inerme Verbenaceae ياسويي زفر

*13 Conocarpus lancifolius Combretaceae )الدهس )قرم اليابسة

14 Dodonea viscosa Sapindaceae ديدوًيا

51 Hibiscus rosa sinensis Malvaceae هبسنس

16 Jatropha

integerrima Euphorbiaceae جاتروفا

17 Nerium oleander Apocyonaceae دفلة

*18 Parkinsonia acutifolia Caesalpiniaceae شىك القدس



No. Scientific Name Family Name Arabic Name

*11 Pithecellobium dulce Mimosaceae صبار هٌدي

20 Pittosporum tobira Pittosporaceae بيتىسبىرم

21 Pongamia glabra Leguminosae بىًجاهيا

*22 Prosopis juliflora Mimosaceae الغىيف

*23 Prosopis spicigara Mimosaceae الغاف

24 Ricinus communis Euphorbiaceae خروع

*25 Salvadora persica Salvadoraceae )الراك)فرشة األسٌاى

26 Sesbania aegyptiaca Leguminosae السيسباى

27 Tabebuia rosea Bignoniaceae تابىبيا

*28 Tamarix articulata Tamaricaceae ة(األثل )الطرف

29 Terminalia arjuna Combretaceae اللىز الهٌدي

30 Terminalia catapa Combretaceae اللىز

*31 Thesbesia populena Malvaceae الشوسية

32 Thevetia peruviana Apocyanaceae ثيفيتا

33 Vitex angus-castus Verbenaceae مف هرين

34 Washingtonia filifera Palmaceae واشٌجتىًيا

35 Zizphus jujuba Rhamnaceae )السدر الهٌدي )جىجىبا

36 Zizphus spina-cristi Rhamnaceae )السدر )الٌبق

*More tolerant spp.

Developmental Perspectives of Protective Windbreaks -Dec. 2013

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