slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Effect of retained trees on growth and structure of young Scots pine stands PowerPoint Presentation
Download Presentation
Effect of retained trees on growth and structure of young Scots pine stands

Loading in 2 Seconds...

play fullscreen
1 / 19

Effect of retained trees on growth and structure of young Scots pine stands - PowerPoint PPT Presentation


  • 256 Views
  • Uploaded on

Effect of retained trees on growth and structure of young Scots pine stands Juha Ruuska, Sauli Valkonen and Jouni Siipilehto Finnish Forest Research Institute, Vantaa, Finland Maintain specific ecological processes (habitats) Create structurally complex stands

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Effect of retained trees on growth and structure of young Scots pine stands' - mike_john


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Effect of retained trees on growth and structure of young Scots pine stands

Juha Ruuska, Sauli Valkonen

and Jouni Siipilehto

Finnish Forest Research Institute,

Vantaa, Finland

green tree retention
Maintain specific ecological processes (habitats)

Create structurally complex stands

Maintain aesthetic values

Promote regeneration

Green tree retention
  • An integral part of contemporary forestry in Europe

Objectives

slide3

Problems

  • Poorly stocked gaps around retained trees (poor sites in N. Finland)
  • Loss of harvested volume
  • Logging damage, higher logging costs
  • Poor stability in solitarydistributions
hypotheses
In the vicinity of Retained Trees (RT),

Seedling stand density is lower

Seedling height and diameter growth is slower

Influence on diameter growth is greaterthan on height growth,and seedlings are slimmer (height-diameter ratio)

Seedlings have smaller and less branches

Hypotheses
  • and
  • An aggregated RT distribution is less harmful than a dispersed distribution
study stands
9 stands in Southern Finland

Most Scots pine upland sites covered

Seedling stand dominant height of 2-7 m

Scots pines retained for 8-18 years

Variable RT densities (32 - 117 ha-1)

Variable but mostly scattered spatial distributions

No significant tree removals or mortality

Study stands
  • A sample of planted or naturally generated
  • Scots pine seedling stands with RT
sampling
8 seedling sample plots per RT sample tree

Plots systematically at 1, 3, 6 and 10 m distance from RT

Seedlings measured for h, dbh, coordinates

One sample seedling per plot per species selected among main crop seedlings (h, dbh, cr, cw, h growth, d growth, branch diameters etc.)

One additional sample seedling per species to represent non-main crop seedlings

Sampling
  • All RT mapped, measured for dbh, h
  • 10 sample RT per stand
    • measured for trunk and crown variables, t, dbh growth
approach
Growth models

For pine seedlings, RT

Individual tree, spatially explicit

Models for branching

Max branch diameter and branch cross sectional areaof 3 whorls; for pine only

Simulation

Seedling diameter and height growth

Branching variables

Subject to site, density of the seedling stand, number and diameter of RT,and RT spatial distribution

Approach
overstory influence
Light interception is not the critical factor

Low interception rate with pine (15 % with 50 RT ha-1)

Root competition is

Water, nutrients

Greatest on poor sandy soils

Extent

Roots up to >10 m

Greatest near RT base

Great variation in shape

Overstory influence

Root density and distance from a retained Scots pine tree (Kalela 1954)

description of tree competition
A spatial competition index

Incl. RT and seedlings

Ecological field theory: resource availability(Wu et al. 1985)

Index = f(diameter, distance)

Max value = 1 (with max RT d in data and zero distance)

Description of tree competition

Competition effect of one tree by

diameter and distance

results 1 rt effect on seedling stand density
Results1. RT effect on seedling stand density
  • Seedling stands were dense
    • 3,700-37,000 Scots pine seedlings ha-1
  • Virtually no RT influence on pine density
  • Clearly less birch near RT
  • Greater RT effect in Northern Finland(Niemistö et al.1993)
2 seedling height growth
2. Seedling height growth
  • Cumulative growth = height
    • Clearly smaller pine seedlings near RT
    • Smaller effect than in Northern Finland (Niemistö et al.1993)

Relative height of pine seedlings

and RT distance and diameter

slide12

3. Seedling diameter growth

  • Cumulative growth = diameter
    • RT effect negligible compared to that of stand density
    • Equal RT influence on height and diameter growth
    • Tree form not influenced by RT

Diameter of 5 m high pine seedlings,

RT distance and diameter, and seedling stand density

4 maximum branch diameter
4. Maximum branch diameter
  • Diameter of the thickest branch of a pine seedling
    • Slightly smaller near RT for given seedling height
    • Effect was minor compared to that of
      • Site index
      • Competition from other seedlings

Influence of RT diameter and distance, site (H100),

and seedling stand density on the maximum branch

diameter of a 5 m high pin seedling

5 total branching
5. Total branching
  • Sum cross-sectional area of branches in 3 whorls
    • Clearly less near RT
    • More pronounced than on maximum branch diameter
    • Site index and competition from other seedlings also had a strong effect

Influence of RT diameter and distance, site (H100),

and seedling stand density on the total branch

Cross-sectional area of 3 whorls of a 5 m high pine seedling

6 spatial distribution of rt
6. Spatial distribution of RT
  • Simulated alternatives
    • 16 to 48 RT ha-1
    • Average RT dbh 25 cm and height 21 m
    • 15-year simulation period
    • Random, regular and clustered RT distribution
  • Results
    • RT spatial patterns had only a marginal effect on growth and branching of pine seedlings
    • 48 RT ha-1 reduced average seedling height 15%, diameter 11-16% and maximum branch diameter 9-10% compared to no retention
conclusions i
RT do not reduce seedling stand density in S Finland as much as in N Finland

Can help control birch on problem sites

Influence on diameter growth is not greaterthan on height growth, and height-diameter ratio is not affected much

Seedlings have smaller and less branches, but the maximum branch diameter is not reduced much

Reduction in branching is small compared to that achieved by higher density, site-species match

An aggregated RT distribution is only little less harmful than a dispersed distribution

Conclusions (I)
conclusions ii
In that sense,

the current practice with 5-10 trees ha-1seems not to have a great effect on wood production

Growth effects are small

No unstocked patches in the south

Not effective in quality improvement

It is a small improvement that groups are now placed near stand edges, or on special uncut sites

Conclusions (II)

Retention is practiced for ecological

and aesthetical purposes.

It is not mandated by law but is strongly suggested

for example during a certification process.