MÔN QUẢN LÝ THẢM THỰC VẬT RỪNG: :" Density Management"

tổng quan những nghiên cứu thảm thực vật rừng dễ cháy và dự báo cháy rừng một số thảm thực vật rừng quan trọng trên thế giới quản lý động thực vậtphân loại thảm thực vật rừng thảm thực vật rừngkhái niệm thảm thực vật rừng vai trò của thảm thực vật rừng thảm thực vật rừng nhiệt đớithảm thực vật rừng cúc phươngthảm thực vật rừng việt nam

Ways to control competing species

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What is thinning?

A cultural treatment made to reduce stand density of trees primarily to improve growth, enhance forest health

or recover potential mortality (SAF 2008)

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What is thinning?

Normal thinning does not significantly alter the gross production of wood volume

Thinning can be commercial or non-commercial, depending on landowner objectives and local markets for

Reasons to thin

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The importance of tending an even-aged stand is illustrated by comparing these two plots in the famous Star Lake thinning experiment started

by Fred Wilson with red pine planted in 1913 (WFMG, 2011)

Enhance the vigorous growth of selected trees through the removal of competitors

Improve the diameter of target trees and reduce the length of cutting cycle

Improve tree morphology to enhance valuable trees

Economic objectives of thinning

Harvest most merchantable material produced by the stand during the rotation

Increased value from rapidly growing larger diameter trees

Increased value from improvements in product quality

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When thinning

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How and when thinning is applied depend on:

Landowner objectives and wanted benefits

Ecological considerations (e.g site quality, species composition, stand structure, and stand condition)

Economic considerations (e.g costs and benefits, local markets)

Social considerations (e.g regulations, aesthetics)

Other past and planned management activities

When thinning

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Selecting removed trees

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Negative selection: removal of suppressed and

poorly formed trees (shown in grey) without

considering the growth of remaining trees

Selecting removed trees

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Positive selection: competing trees are removed

(shown in grey) to maximize the growth of the ‘best’

trees (shown in yellow)

Negative selection vs Positive selection

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Effect of Thinning on Stand Growth

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Production function for an

even-aged stand thinned three times

Effect of Thinning on QSD

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Thinning increasing slope due to better

radial growth of residual trees

Thinned

Unthinned Thin 1

Spacing vs Diameter

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Density vs Diameter

P Radiata @ age 20, Woollens et al (2002)

16Stocking density vs crown development

Timing of thinning effect diameter

growth responses

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Early thinning can yield increased

diameter growth when compared

to later or no thinning

Forest Health

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Fire Hazard

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Mid- or late-rotation fertilization

 Short rotation plantation forestry

 Provide material for wood product processing

 Large investment (intensive cultivation)

 Increased growth rate

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Mid- or late-rotation fertilization

Mid- or late-rotation fertilization

 Usually applied when site is fully occupied and there is little

competing vegetation

 Crown ratio >30%

 Combine with thinning if stands overstocked or small crown ratio

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Thinning and Fertilization

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The growth response is additive, fertilization in conjunction with thinning, this is a beneficial rotation practice

mid-To realize the full benefits of fertilization, do not thin or harvest within six years of fertilizing

Thin dense stands (those with a BA greater than 130) prior to or within two years of fertilization

Common fertilizers in southern pines

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