QUẢN LÝ THẢM THỰC VẬT: SITE PREPARATION (LEC 11)

Site Preparation

The treatment of the soil and ground vegetation to prepare the soil surface as a favorable seedbed for
either naturally or artificially regeneration.

Seed disseminating

1


Site Preparation

Site preparation includes:

Controlling undesirable vegetation;
Improving soil structure, drainage and fertility;
Reducing logging slash

2


Purposes of Site Preparation

Reduce/eliminate competing vegetation

Remove competing vegetation from the site

3


Purposes of Site Preparation

 Reducing logging slash to regeneration

Slash can impede regeneration both physically and biologically (insects, mammals,
pathogens)
4


Purposes of Site Preparation

 Improve character of seedbed
•Organic Vs bare mineral soil seedbed 
•Promote decomposition of surface organic
matter

•Improving the soil structure for regeneration

5


Methods of Site Preparation

Mechanical
Chemical
Burning

6


Mechanical treatments

 Physical manipulation of site
 Usually with large machinery

Preparing the site by hand is possible and economical only for relatively small-scale projects, where the labour of clearing the
competing vegetation and working the soil is not too time-consuming.

7


Mechanical treatments

Mechanical site preparation with heavy equipment can be divided into three categories:

1.
2.
3.

breaking or crushing vegetation in place
moving vegetation from the planting site
manipulating soil structure or microtopography of the site

8


Breaking Vegetation (Chopping)

A significant advantage of rolling choppers is that they do not displace the topsoil and they have a minimal effect
on soil runoff. 

The most frequently-used tool used to crush existing vegetation in place is the rolling drum chopper
9


Moving Vegetation from the Planting Site (Shearing)

A more intensive treatment is the use of a shearing blade: a horizontal knife blade mounted on a large
crawler tractor which shears vegetation at the ground line. 

Shearing can cause topsoil and
seedbed displacement

10


Manipulating the Soil

Disking

to break up or till the soil surface, improving soil aeration and moisture movement, and helping young trees to
root. Disking also incorporates organic surface layers into the underlying mineral soils and prepares the
surface for bedding where appropriate

11


Manipulating the Soil

Bedding

Bedding against the slope is essential to minimize soil erosion on upland sites

12


Manipulating the Soil

Ripping

Ripping encourages more deep root development than any other of the other soil treatment methods

13


Chemical treatments
Use of chemicals (Herbicide) to manipulate the site in preparation for regeneration

14


Chemical treatments

Chemical site preparation can be an effective method to temporarily control competing vegetation for plant
growth.

Chemical methods may involve simple equipment, can be less expensive, and provide longer control than
mechanical site preparation.

Chemical

effectiveness depends on the appropriate herbicide selection, the timing of application and

application rate.

15


Chemical treatments

16


Chemical treatments

Strip application

Spot application
17


Prescribed burning
Prescribed burning, or controlled ground fires, can be an effective and inexpensive means of removing or
reducing vegetation, and preparing a suitable seedbed in advance of planting or seeding.

18


Prescribed burning
Effective and safe use of prescribed fire requires:

Proper design of the fire breaks;
Personal protective equipment;
Careful evaluation of weather conditions on the day of
the burn, and training

19


Prescribed burning - Advantages

 Relatively cost effective for large areas
 Reduces slash, debris, litter, fuels and competing vegetation
 Improve soil nutrient levels
 Destroys pests/diseases
 Induces sprouting

Melia azedarach ‘ seeds need to be treated by using fire before
disseminating

20


Prescribed Burning - Limitations

 Must adhere to the burn permit laws
 Damage to residual trees (depending on intensity and speed) – heated above 55C
Loss of nutrients (e.g. N) to atmosphere and
erosion

Air quality, visibility and smoke

Alteration of soil properties – degradation
Removal of organic material