Trees & Hurricanes - University of...

Trees & Trees & HurricanesHurricanes

Henry MayerMiami-Dade Extension

June 25, 2009http://miami-dade.ifas.ufl.edu

South Florida is “Hurricane Country”

COULD BE YOUR CAR!!!COULD BE YOUR CAR!!!

With dedication to a management plan, your community can become a model for others

A Healthy and Wind Resistant Urban Forest:

��

� ��

��

��

��

��

��

��

��

Perception of tree benefitsPerception of tree benefitsBroward County

Hillsborough County

Pros

Broward County

Hillsborough County

Cons1. Hurricane damage from trees

1. Hurricane damage from trees

2. Tree damage to infrastructure

2. Falling trees & branches on power lines

3. Falling branches & trees on power lines

3. Tree damage to infrastructure

4. Falling branches and trees on property

4. Block signage

1.Provide shade

Improve

2.Aesthetics

3.Provide unique community

Character

4. Increased Property values

1. Improve aesthetics

2. Provide shade

3. Increased property values

4. Provide unique community character

Urban Forests in 2007Urban Forests in 2007--20082008

Urban forests are different & constantly changing

*http://www.nrs.fs.fed.us/data/urban/state/?state=FL

Results for Miami-Dade County

• 36.7 Million trees,–83% in private lands

• 107 different tree species,• 3.7% on street right of ways,• CO2 sequestration: 564,490 t per

year,• CO2 storage: 5,496,000 t,• Avoided CO2: 35,000 t per year

A GREENPRINT FOR OUR FUTURE:MIAMI-DADE COUNTY

STREET TREE MASTER PLAN

MD Public Works RAAM

Recommendation:Establish and manage a healthy urban forest to improve wind resistance by:

� Having a comprehensive

tree management plan

� Having a structural pruning program

for young and mature trees

� Choosing more wind

resistance species

� Selecting the right species

� Designing the right place

� Planting high-quality trees

• Urban forest conditions such as overall tree canopy and composition

Urban Forest Loss Depends on:

• Tree species, age, health, and structure

• Conditions during the hurricane such as precipitation and the time to move through an area

• Site characteristics such as soil conditions (for example soil depth and moisture)

� ��

��

�� !" �� #��

��

��

��

$�� %��

$��

$�� %��

& ��

��% ��

'��

��

"��

��

��

��

��

( �� #

( �� #

��) �%��

) �%��

�� * ��

��

��

��

"��

"��

��

+ �� # ��

, ��%��

, ��

, � ��

��

��

- ��

��

�� "��

� �� !��

� �� !��

�� * ��

��

- ��

��% �� !" ��

. ��

. ��

"��

"��

�� //

��% ��

��

��% ��

��% ��

, �� /

��% ��

��

��

* ��%��

, ��

) ��% � �� #��

) ��% ��

!�� / �� !* ,

// ��0 � ��

/// �� !"

http://treesandhurricanes.ifas.ufl.edu

Tree species that have been found to tolerate wind better than others

Species: trees that resist decay make better candidates for restoration

Laurel oakRoyal poinciana

FicusOrchid tree

Live oakMahogany

Gumbo-limboTamarind

Trees prone to decayTrees that resist decay

The higher the wind speed of the hurricane, the more likely trees will fail

0

5

10

15

20

25

30

35

40

75 95 115 135 155 175

�� "� �#

$��

��

��

��"%

#

&��

�� '

(��

) �

* ��

+ ��

, ��

- ��.

/��!��

R2 polyn=0.7154

y = 0.0032x2 - 0.4948x + 30.57

Trees in groups survive winds better than trees growing

individually

When a tree fails or is removed, plant and maintain a new tree in

its place

0

10

20

30

40

50

60

Jeanne Ivan Charley120 mph 130 mph 145 mph

Bra

nche

s Lo

st (%

)

0000

0000

0000

0 - 8 in.

9 - 20 in.

21 - 39 in.

40 - 79 in. The larger and older a tree is,

the more branches it will lose.

Older trees are more likely to fail in hurricanes

Unhealthy trees are predisposed to hurricane damage

Common Causes of Tree Failure

��

Well-pruned trees survive better than unpruned trees

Live Oak Black Olive Gumbo Limbo0

20

40

60

80

100

1 ��

��

Tree

s S

tand

ing

Aft

er H

urri

cane

(%)

Why do we Prune?Why do we Prune?

Weak vs. Strong

Good structureGood structure

Case Study: Weston Lakes Maintenance Association, Weston, FL

Structural Pruning of 100 Common Area and 700 Swale Mahogany Trees

Case Study: Weston Lakes Maintenance Association, Weston, FL

Structural Remediation Complete

64%survival

0 to 3 m2

(0 to 39 ft2)

Street trees,Parking lots, Yards

73%survival

91%survival

Yards,Parks

4 to 7 m2

(40 to 75 ft2)> 7 m2

(> 75 ft2#

Campuses, Parks, Yards

Trees with more rooting space survive winds better


Lack of mature rooting space/site constraints

� Give small trees

at least 10’ by 10’

� Give medium

treesat least 20’ by 20’

� Give large trees at least 30’ by 30’

Recommendation:

Give trees enough rooting space according to their mature size

Courtesy: James Urban

Six things can happen to a tree in a hurricane:

1.Uproots

3.Main Stem Breaks2.Branches Break

6.Leaf Loss

5.NoVisibleEffects

4.Leans4.Leans

Response PlanImmediately following stormStep 1: Remove hazards

Step 2: Stake fallen trees where possible

Step 3: Clean canopies of damaged trees

Before the next visit• Allow trees to regenerate energy reserves

• Develop a tree management program in the community

RECOMMENDATION: If a large tree uproots and falls over, it is basically dead and should be removed.

UprootUproot

A small tree (under 4 inches in diameter) may be righted. Its future care needs to include staking and

watering as though it was freshly planted.

UprootUproot

How to Stand a Tree Up• Water as if the tree were

recently planted. Irrigate 3x a week with 3 gallons/inch trunk diameter. There is no

need to fertilize at this time.•Stake the tree. Adjust stakes and remove when tree is stable.

The main stem breaksThe main stem breaks

� is essentially dead as an urban tree� should be removed

Lose large or small broken branches

� Large broken branches may be able to be repaired through pruning. � Small branches can be pruned.� If a tree has lost more than ½ its crown, it may never regain its structure and health

Canopy Cleaning

Make clean cuts on stubs, breaks, and tears.

Reduce back to lateral branch if one is present.

��

��

Bad cut-called a flush

cut

Wound wood does not develop evenly.

Lions-tailing Lions-tailing:trees with foliage concentrated at the tips of branches because inner branches were removed.• More susceptible to hurricane damage• Difficult to restore

Lions-tailed trees failed

Pruning program

Time needed

to restore:

• 4 + yrs.• four or more visits

• 3 – 4 yrs.• about threevisits

• 2 – 3 yrs. • about two visits

Mature (over 10” dbh)

Medium-aged (5-10”

dbh)

Young (under 5” dbh)

* dbh – diameter at breast height

Sproutsemerging

Reduce some- Shorten 1/3 of the sprouts. They will continue to store energy, but will eventually be removed.

Remove some- Remove 1/3 of the sprouts to allow space for the most vigorous ones to grow.

Leave some- These will develop into the new branches.

Remove or Remediate?Remove or Remediate?

Remove broken fronds that are smothering the bud

UNPRUNED ACCEPTABLE OVER PRUNED

Pines may show no immediate visible damage after a hurricane but may decline over time

No visible effects

Contract specification requirements: All trees FL grade No. 1 or better; UF-IFAS planting detail; post-plant inspection;

Planting

Root flare needs room to expand

Planting issues Planting issues –– 5 5 ”” too deeptoo deep

Pre-plant root ball inspection, excavation and preparation

Kept covered and moist, the cut ends do regenerate an amazing number of roots.

Trees with damaged root systems are more vulnerable to the wind


Poor maintenance practices

Removed it!!

1 �� 21 �� 2

Trees & Hurricanes - University of...

Documents

Transcript of Trees & Hurricanes - University of...