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

The treatment of the soil and ground vegetation to prepare the soil surface as a favorable seedbed for either naturally or artificially regeneration. Organic Vs bare mineral soil seedbed  Promote decomposition of surface organic matter Improving the soil structure for regeneration

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

Site Preparation

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Site preparation includes:

Controlling undesirable vegetation;

Improving soil structure, drainage and fertility;

Reducing logging slash

Purposes of Site Preparation

Reduce/eliminate competing vegetation

Purposes of Site Preparation

 Reducing logging slash to regeneration

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

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

Methods of Site Preparation

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Mechanical

Chemical

Burning

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.

Mechanical treatments

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

1. breaking or crushing vegetation in place

2. moving vegetation from the planting site

3. manipulating soil structure or microtopography of the site

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. 

Moving Vegetation from the Planting Site (Shearing)

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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

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

Manipulating the Soil

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Bedding

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

Manipulating the Soil

Ripping

Chemical treatments

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

Chemical treatments

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Chemical treatments

Strip application

Prescribed burning

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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

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

Prescribed burning - Advantages

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 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

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