ICFR / Central & Mpumalanga Regional Interest Group Field Day · 08.30-09.00 Meet for Tea & Coffee...

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© ICFR 2011 ICFR Central & Mpumalanga Regional Field Day

ICFR CENTRAL & MPUMALANGA REGIONAL FIELD DAY

Date: Thursday 13

th October 2011

Venue: Warburton Club

Time: 08h30 for 09h00

PROGRAMME

NB Please note that PPEs are required for the field visits.

08.30-09.00 Meet for Tea & Coffee at the Warbuton Club

09.00-09.10 Welcome and introduction to the field day Colin Dyer ICFR

09.10-09.40 Modelling susceptibility of pine forests to Sirex noctilio:

A bioclimatic approach Ilaria Germishuizen ICFR

09.40-10.10 An update on the South African Sirex Control

Programme operational activities Philip Croft ICFR

10.10-10.40 Role of nursery infection with Fusarium circinatum

and stress on post-plant survival of Pinus patula Marnie Light ICFR

10.40-11.00 Tea or Cooldrinks

11.00-11.30 Genetic gain in breeding population of Eucalyptus

nitens Tammy Swain ICFR

11.30-12.00

Identifying sites responsive to mid-rotation fertilisation

of Eucalyptus pulpwood and post-thinning fertilisation

of Pinus sawtimber plantations: Some early growth

responses

Louis Titshall ICFR

12.00-12.20 Travel to first field stop

12.20-13.00 Manual to Mechanised – Why? Danie Scheepers Bosbok

Ontginning

13.00-13.20 Travel to second field stop & lunch

13.20-13.50 Update on Leptocybe invasa, Thaumastocoris

peregrinus and Coryphodema tristis research

Izette Greyling

Dawit Degefu &

Marc Bouwer

FABI

13.50-14.30 Travel to 3rd field stop

14.30-15.00 Effect of harvesting operations on a granite derived soil

on the growth of Pinus patula (K8 trial) Diana Rietz ICFR

15.00 End of field day

Cover photograph: Marnie Light, ICFR 2011


Modelling susceptibility of pine forests to Sirex noctilio:

A bioclimatic approach

Ilaria Germishuizen [email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville, 3209

Summary

Understanding the current and potential distribution of pests and pathogens across the landscape is an

essential component of pest management. Climate is one of the major factors limiting the distribution

of pests and pathogens and climatic variables have been successfully used to predict Sirex spread. A

machine learning model based on bioclimatic variables was developed in Random Forest (R) to

determine which pine forests in South Africa are more susceptible to Sirex infestations. The most

important bioclimatic variables in predicting the susceptibility to Sirex were high maximum

temperatures, low rainfall, particularly in late winter/early spring, and high evapotranspiration, showing

that pine forests that experience stress are more susceptible to Sirex infestation. The predictive power

(F value) of the model was 0.92 (estimate predictive error: 7.6%) for the Summer Rainfall Region area

and 0,85 (estimate predictive error: 15.2%) for the Winter Rainfall Region area. The model was

implemented in a spatial framework at the landscape level (farm level) and at the company level for all

pine compartments of 10 to 20 years of age, and each spatial unit was assigned a score between 0 and

1, representing the susceptibility to Sirex.

Results for the pine forests compartments in the summer and winter rainfall regions are shown in Table

1 and Table 2.

The Sirex risk model has proved to be a useful tool at the operational level in the Sirex Control

Programme, particularly with regards to monitoring, early detection and trap sites selection. The

potential value to the companies at the management level has not yet been fully explored.

The current model is based on bioclimatic variables that describe climatic stress independently from the

land use and management. Parameters such as species, site quality, age at last thinning of sawtimber

stands, weed management, drought and fire may be included in the model to refine its predictive

strength at the compartment level.

Table 1: Sirex risk classes in the pine compartments of 10 to 20 years in the summer rainfall region of

South Africa.

Risk Class TOTAL (ha) %

< 20% 19,791 8

20% - 39% 82,095 33

40% - 59% 131,556 53

60% - 79% 6,618 3

80% 6,289 3

Total Pine 10 years 246,349≥

≥


< 20% 19,791 8

20% - 39% 82,095 33

40% - 59% 131,556 53

60% - 79% 6,618 3

80% 6,289 3

Total Pine 10 years 246,349≥

≥


Table 2: Sirex risk classes in the pine compartments of 10 to 20 years in the winter rainfall region of South

Africa.


< 20% 40,333 71

20% - 39% 7,979 14

40% - 59% 2,693 5

60% - 79% 1,319 2

80% 4,395 8

Total Pine 10 years 56,719

≥

≥


< 20% 40,333 71

20% - 39% 7,979 14

40% - 59% 2,693 5

60% - 79% 1,319 2

80% 4,395 8

Total Pine 10 years 56,719

≥

≥


An update on the South African Sirex Control Programme

operational activities

Philip Croft [email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville, 3209

Summary

This presentation will answer the following questions:

• Update of Sirex

o Where is Sirex in the country now?

o What is planned for the next flight season or geographical spread of Sirex?

• Sirex Risk Rating

o How do we use the risk rating effectively?

o How to monitor Sirex damage using the risk rating?

o Action points

• Update on biological control application

o What are the requirements for 2012 Inoculation season?

o Where has Ibalia been released to date?

• Myths about Sirex?

Sirex is now in Mpumalanga, and will continue to move northwards. The Sirex trap programme will

enable us to follow the movement of the wasp into new areas. Emergence cages will indicate the

effectiveness of the inoculations and nematodes.

Information on the areas at high, medium and low risk to Sirex is now available at a high level or

landscape level and at a compartment level. Maps indicating the results are available. This information

is vital in managing plantations in such a way that Sirex risk can be reduced and prevents the loss of

timber. Some good silviculture pointers are discussed.

Biological control for 2012 must be planned early to ensure FABI have sufficient time to produce the

quantity of nematodes that are required. The risk rating allows us to inoculate in the most effective

manner reducing the Sirex population in the high risk areas. Ibalia wasps, also a very effective control

measure have been released in Mpumalanga and we plan to release more next year.

To dispel some myths regarding Sirex control, when a few points that are often true or assist in Sirex

control, are used to control Sirex, a false comfort zone is created. Only those measures that reduce the

Sirex population, ultimately win the day.


Take Home Points:

� Monitoring is key to Sirex population reduction as it leads us to areas requiring treatment.

� Risk rating affects the way the programme deploys nematodes, Ibalia and traps.

� Biological control is effective when carried out correctly and the logs are left in field.

� Inoculations must take place in March, April and May. Late inoculations are less successful.

� Ensure field staff know what Sirex infested trees look like and ensure they report Sirex damage.

Contact Details:

Philip Croft

072 272 9326

033 386 2314

[email protected]


Role of nursery infection with Fusarium circinatum

and stress on post-plant survival of Pinus patula

Marnie E. Light [email protected]

Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville 3209

Summary

Fusarium circinatum, the causal agent of pitch canker fungus (PCF) in mature pine trees, is particularly

associated with causing significant losses of pine seedlings in nurseries in South Africa (Wingfield et al.,

2002). Symptoms of infection include shoot-tip die back and discoloration of the roots and root collar

region, resulting in seedling mortality. Fusarium circinatum is also responsible for the high mortality

observed in young Pinus patula trees up to two years after establishment (Crous, 2005). This results in

serious losses through poor stocking and variation in stand growth.

To gain a greater understanding of the role of nursery infection with F. circinatum and the effect of

stress on the survival of P. patula seedlings in the nursery and at establishment, a collaborative industry

trial was carried out in 2010/11, under the direction of the South African Pitch Canker Control

Programme. This Industry PCF trial, conducted in a PCF-free environment, clearly indicated that the PCF-

induced mortality in the field is directly linked to the inoculum in the nursery. Hence, seedlings infected

with PCF in the nursery will not survive, even under optimum planting conditions. Findings, to date,

from this Industry trial will be presented.

References

Crous JW. 2005. Post-establishment survival of Pinus patula in Mpumalanga, one year after planting.

Southern African Forestry Journal 205: 3-11.

Wingfield MJ, Jacobs A, Coutinho TA, Ahumada R and Wingfield BD. 2002. First report of the pitch

canker fungus, Fusarium circinatum, on pines in Chile. New Disease Reports. Volume 4 August

2001 - January 2002, http://www.bspp.org.uk/ndr/.


Genetic gain in a breeding population of Eucalyptus nitens

Tammy Swain [email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville 3209

Introduction

Eucalyptus nitens is an important commercial cold tolerant eucalypt species currently grown in the

summer rainfall regions of South Africa. Of the provenances grown in this country, significant variation

exists for frost, cold and drought tolerance, as well as flowering, seed production and pulping

properties, making this species ideally suited to improvement. However, the fact that E. nitens is a

reticent or shy flowerer (Gardner, 2003) has hindered this breeding programme. Reticent flowering may

also be affecting realised or actual gain, in that only certain families may be contributing as pollen

parents every year, thus potentially causing marked differences from predicted gain. On the contrary, if

different or additional families start flowering with each advancing year, gain may vary significantly on

an annual basis.

Two series of 2nd

generation E. nitens trials were established on temperate sites in KwaZulu-Natal (KZN)

and Mpumalanga (MPU) in 1999 and 2008 to test the progeny produced from ICFR seed orchards, and

to continue selectively improving this material. In 2001, three genetic gain trials were established in the

same regions to quantify how much improvement has been made in the E. nitens breeding programme,

and to determine whether a range of seed orchard factors influence progeny gain.

Materials and Methods

Details of the trial sites and trial designs for the genetic gain trials are included in Table 1. Twenty-five to

28 treatments were included in the trials, details of which can be found in Table 2. In addition to

comparing improved with unimproved material, treatments included seed orchard bulks comprising a

mix of the same mother families originating from different seed orchards i.e. half sibs, to determine if

seed orchard origin plays a role in progeny performance. All bulks from a specific seed orchard were

also combined in another comparison, irrespective of flowering percentage, to further examine the

relationship between seed orchard origin and gain. To establish whether the number of trees flowering

simultaneously in a seed orchard impacts on progeny performance i.e. assuming increased outcrossing

with increased flowering, treatments were included that comprised bulks of the same families, but

which were collected in different years to represent different percentages of flowering in the orchards.

Lastly, bulks comprising different family combinations were included to determine whether this played a

significant role in achieved gain being commercially deployed.

Table 1. Site and trial design details of three Eucalyptus nitens genetic gain trials in South Africa.

Plantation Date

Planted

Latitude o(S)

Longitude o(E)

Altitude

(m a.s.l.)

MAP

(mm)

MAT

(oC)

Soil depth

(mm)

No. of

treatments Design

Balgowan, KZN 05/02/01 -29.4044 30.02417 1498 1002 15.3 1000-1200 28 5x6 unbalanced lattice

Amsterdam, MPU 20/02/01 -26.5728 30.72778 1478 881 14.8 700 26 Unbalanced lattice

Lothair, MPU 22/02/01 -26.4833 30.63333 1600 869 14.6 800 25 5x5 triple lattice

MPU – Mpumalanga, KZN – KwaZulu-Natal, MAP – Mean Annual Precipitation, MAT – Mean Annual Temperature


Table 2. Treatments included in the Eucalyptus nitens genetic gain trials at three sites in South

Africa.

Treatment

no.

Origin and year seed collected

(flowering percentage in previous year)

Treatment/

Bulk composition

Presence in trials

Balgowan Amsterdam Lothair

1 E88/01 Jessievale SO1

A 1998 (15%)

27832

31328

31329

31331

31332

31337

32101

32098

√ √ √

2 E88/01 Jessievale SO A 1999 (40%) “ √ √ √

3 E88/03 Helvetia SO B 2000 (44%)

32079

32087

32089

32090

32093

32095

32097

32100

√ √ -

4 E88/01 Jessievale SO B 1998 (15%) “ √ √ √

9 E88/01 Jessievale SO B 2000 (45%) “ √ √ √

10 E88/05 Jaglust SO B 2000 bulk (47%) “ √ √ √

5 E88/01 Amsterdam SO C 1998 (20%) Top 70% families √ √ √

6 E88/05 Jaglust SO D 1998 bulk (47%)

27832

31331

31338

32084

32087

32091

32092

32094

32095

32096

32097

32099

32100

32101

32102

√ √ √

7 E88/01 Jessievale SO D 1998 bulk (15%) “ √ √ √

8 E88/03 Helvetia SO E 2000 (44%)

32087

32093

32095

32096

32100

34831

34832

34833

34835

34836

34837

34838

34839

34840

√ √ √

11 E88/01 Jessievale SO 1998, top family 32097 √ √ √

12 E88/01 Jessievale SO 2000, top family 32097 √ √ √

13 E88/03 Helvetia SO 1999, top family 32097 √ √ -

14 E88/03 Helvetia SO 2000, top family 32097 √ √ √

16 E88/05 Jaglust SO 1998, top family 34832 √ √ √

17 E88/03 Helvetia SO 2000, top family 34832 √ √ √

18 E88/05 Jaglust SO 1998, top family 37232 √ √ √

19 E88/05 Jaglust SO 1998, top family 37224 √ √ -

20 Landrace commercial bulk, ex Dorstbult SO, SA2 - √ √ √

21 Improved commercial bulk, ex Helvetia SO, SA - √ √ √

22 Unimproved general bulk ex Australia

32083

32091

32092

32093

32096

32099

32101

34832

34838

37628

√ √ √

23 Unimproved average family ex Nelshoogte, SA 28 √ √ √

24 Unimproved top family ex Badja, Australia 37232 √ √ √

26 Unimproved top family ex Barren Mountain, Australia 32097 √ √ √

27 Unimproved top family ex Barrington Tops, Australia 34832 √ - √

28 Unimproved local E. nitens ex Perdestal, SA, 1989 - √ √ √

29 E. grandis x nitens (GXN) clone ex Sunshine Seedlings, SA - √ √ √

30 Controlled pollinated full sib seed ex South Africa - √ - √ 1 Seed orchard

2 South Africa

Results

Diameter at breast height (dbh) and height measurements were carried out at Lothair and Amsterdam

at 87 months after establishment and at Balgowan at 97 months. Individual tree volume was calculated

from these measurements using the equation developed by Schonau (1982), and total treatment

volumes were calculated per plot and then estimated per hectare, taking survival into account. Table 3

presents the final measurements of these trials, across all sites.


• There were significant differences (p < 0.05) between treatments for all traits, at all three sites,

as well as across sites.

• Significant improvements have been made over the first generation of selection in the ICFR

E. nitens breeding population. Gains that can be made by using improved seed orchard bulks

originating from any of the four ICFR seed orchards included in these trials, irrespective of

significant differences, range from 0.2 to 21.4% increase in dbh and 9.3 to 94.4% in total volume

(Figure 1). This will be dependent on site and bulk used, and is expressed as a percentage of the

unimproved and landrace bulk means, respectively (Shelbourne, 1970).

• Improvement in survival and stocking of the advanced generation material plays a significant

role in the gains achieved.

Table 4 summarises the comparison between seed orchard factors.

• Indications are that levels of flowering have an impact on progeny growth. Higher flowering

percentages resulted in better progeny growth, suggesting that seed should only be collected

from seed orchards where more than 40% flowering was observed in the previous year. It is

uncertain whether further improvements in growth would be achieved if flowering levels were

higher i.e. 60%.

• Seed orchard origin appears to have no effect on progeny growth in this trial series, irrespective

of flowering levels. This suggests that seed collected from any of the four ICFR seed orchards

tested in the trial series, will produce trees with significant improvement in growth.

Figure 1. Percentage gains of Eucalyptus nitens improved seed orchard bulks over unimproved

bulk (Treatment 22) and improved landrace bulk (Treatment 20).


Table 3. Final combined site total volume, dbh, height and individual tree volume treatment

means for three Eucalyptus nitens genetic gain trials in South Africa at 87 to 97 months.

(Values followed by the same letter of the alphabet are not significantly different from

each other (p > 0.05)).

1 Individual tree volume 2 Standard Deviation

Treat-ment

Treat-ment

Survival (%)

Treat-ment

Survival (%)

Treat-ment

Survival (%)

11 254.14 a 17 74 16.39 a 11 78 21.49 a 17 70 0.211 a

17 253.27 a 5 71 15.82 ab 3 75 21.26 ab 11 78 0.196 ab

2 242.65 ab 8 79 15.79 ab 2 78 21.23 abc 5 71 0.194 abc

8 241.42 ab 11 78 15.73 abc 14 71 21.03 abcd 8 78 0.193 abc

27 231.97 abc 2 78 15.61 abc 6 75 21.02 abcd 14 71 0.188 abcd

5 228.22 abc 14 77 15.57 abcd 13 71 20.88 abcd 2 78 0.187 abcd

1 225.43 abc 9 71 15.56 abcd 17 65 20.77 abcde 10 71 0.183 abcde

14 221.32 abcd 16 56 15.46 abcd 4 71 20.72 abcde 13 71 0.182 abcde



3 218.80 abcd 3 75 15.24 abcd 10 82 20.56 abcdef 6 75 0.177 abcde

10 213.92 abcde 10 71 15.20 abcd 1 89 20.34 abcdefg 12 68 0.176 abcde

13 213.00 abcde 13 71 15.16 abcd 8 78 20.23 abcdefg 3 75 0.173 abcde

12 199.13 abcdef 27 89 15.14 abcd 27 71 20.08 abcdefgh 1 89 0.167 abcdef

30 187.67 abcdefg 21 64 15.04 abcd 12 53 19.95 abcdefgh 4 82 0.167 abcdef

4 181.45 abcdefg 1 82 14.83 abcd 24 68 19.92 abcdefgh 27 65 0.162 abcdef

7 178.56 abcdefg 12 69 14.83 abcd 7 73 19.68 bcdefghi 21 64 0.157 abcdef

21 167.20 bcdefgh 4 65 14.63 abcd 30 64 19.61 bcdefghi 30 61 0.155 bcdef

16 166.12 bcdefgh 19 55 14.34 bcd 21 56 19.61 bcdefghi 20 78 0.154 bcdef

20 152.02 cdefgh 18 51 14.33 bcd 16 61 19.53 bcdefghi 29 53 0.150 bcdef

22 141.00 defgh 29 62 14.18 bcd 20 85 19.49 cdefghi 24 48 0.150 bcdef

24 134.30 efgh 23 48 14.18 bcd 19 51 19.30 defghi 7 73 0.143 bcdef

29 127.47 fgh 20 50 14.17 bcd 23 50 19.13 efghi 22 62 0.139 cdef

19 126.85 fgh 7 73 14.03 bcd 26 52 18.94 fghi 23 51 0.137 def

18 123.18 fgh 22 62 13.98 bcd 29 48 18.73 ghij 19 50 0.137 def

23 120.78 fgh 24 56 13.93 bcd 22 62 18.38 hij 26 52 0.135 def

26 115.88 gh 26 52 13.70 cd 28 49 18.04 ij 18 55 0.130 ef

28 92.43 h 28 49 13.54 d 18 55 17.32 j 28 48 0.118 f

Trial mean 185.20 14.97 20.07 0.168

SD2

74.07 4.47 3.86 0.12

Total volume

(m3

ha- 1

)Dbh (cm)

Indiv. tree

volume1

(m3

ha- 1

)

Height (m)


Table 4. Comparison of growth within treatment groups in Eucalyptus nitens genetic gain trials

across all sites. (Values within a treatment comparison followed by the same letter of

the alphabet are not significantly different from each other (p > 0.05)).

Dbh

(cm)

Height

(m)

Indiv. tree volume

(m3ha

-1)

Total volume

(m3ha

-1)

Average improvement

in total volume

(%)

Level of improvement Improved

Unimproved

15.25 a

13.78 b

20.67 a

18.23 b

0.179 a

0.130 b

208.05 a

128.46 b 61.9

Flowering percentage 40 - 47%

15 - 20%

15.48 a

14.81 b

20.78 a

20.33 a

0.182 a

0.167 a

226.75 a

202.44 b 12.0

Year of seed collection1

1999

2000

1998

15.44 a

15.39 a

15.06 a

21.04 a

20.65 a

20.58 b

0.185 a

0.182 a

0.174 a

230.79 a

224.30 a

191.33 b

1999:1998 – 20.6

1999:2000 – 2.9

Seed orchard origin

Amsterdam

Helvetia

Jaglust

Jessievale

15.82 a

15.49 a

15.27 a

15.04 a

20.68 a

20.79 a

20.81 a

20.57 a

0.194 ab

0.185 a

0.180 ab

0.173 bc

228.23 a

231.67 a

199.77 a

213.85 a

-

Composition of seed orchard bulk2

C

E

A

B

D

15.82 a

15.79 a

15.22 ab

15.17 ab

14.66 b

20.68 a

20.23 a

20.74 a

20.77 a

20.23 a

0.194 a

0.193 a

0.177 ab

0.175 ab

0.160 b

228.23 a

241.42 a

234.41 a

207.33 a

198.67 a

-

1 Refer to Table 1 for details of flowering in these years 2 Refer to Table 2 for details of bulk composition

References

Gardner R A W. 2003. Floral induction in Eucalyptus nitens (Deane & Maiden) Maiden in South Africa.

MSc, University of Natal, Pietermaritzburg.

Shelbourne C J A. 1970. Genetic improvement in different tree characteristics of Pinus radiata and

the consequences for silviculture and utilisation. Pp 44-57 in James R N, Sutton W R J and

Tustin J R (Comp.) “Pruning and Thinning Practice”. New Zealand Forest Science, FRI

Symposium No. 12.

Schonau A P G. 1982. Timber volume and utilization tables for six common eucalypts.

Pietermaritzburg: Wattle Research Institute. 64pp. ISBN 0 86980 282 8.


Identifying sites responsive to mid-rotation fertilisation of Eucalyptus pulpwood and post-thinning fertilisation of

Pinus sawtimber plantations: Some early growth responses

Louis Titshall [email protected]

Institute for Commercial Forestry Research, PO Box 100281, Scottsville, 3209 Introduction

Mid- to late-rotation fertilisation of plantation forests has the potential to increase final stand volume,

improve wood quality and possibly reduce rotation length (reduce risk). This may be of benefit to both

short-rotation pulpwood stands and long-rotation sawtimber plantations.

While the effects of fertiliser application at planting are well documented, the effects of mid- to late-

rotation application of fertiliser on the productivity of Eucalyptus is not well known (Germishuizen,

2007). Benefits of post-planting fertilisation of plantations may include an increase in final tree volume

and a reduction in rotation length (reduced risk). This effect may well be considerable on South African

forestry soils as these are reported to be relatively infertile. A series of trials was established to

investigate the potential for productivity responses to nutritional inputs applied at two to three years

prior to clear-felling of eucalypt pulpwood stands, across a wide range of sites.

In the case of sawtimber plantations, post-thinning fertilisation may potentially increase the economic

return on investment by increasing final tree volume or growth rate. Where an increase in growth is

found due to fertiliser application, it is also possible that rotation length could be shortened resulting

in an earlier return in investment and so reduce risk. It is also suggested that wood quality may be

enhanced. Research from the USA has reported that, by thinning the stand prior to fertilisation,

stocking can be reduced which reduces competition for light and water thereby favouring maximum

volume response to nutrient addition (Allen, 1987). A number of researchers have reported positive

results to late-rotation fertilisation. In Australia, four different trials on Pinus radiata showed increases

in basal area and volume in the order of 5 to 30%. These responses were due to the application of

nitrogen (N) and phosphorous (P) in the late-rotation (16 to 30 years) (Crane, 1981; Turner et al.,

1996). In South Africa, volume increases of 20 to 30 m3 ha

-1 were reported five years after the

application of mid-rotation (8 to 13 years old) fertilisation in P. patula stands (Carlson and Soko, 2000;

Campion and du Toit, 2003).

This presentation reports on 15 month basal area growth responses after mid-rotation fertilisation of

a range of eucalypt pulpwood stands, and on the 24 month basal area growth responses after the

application of fertiliser to sawtimber stands that have received a final thinning. The relative responses

to control treatments at each site are also shown, to highlight those sites with a strong positive

response to fertiliser application.


Trial design and treatments

Mid-rotation fertilisation of Eucalyptus pulpwood

Table 1. A summary of trial details for all Eucalyptus pulpwood mid-rotation fertilisation trials

implemented since 2007. Darkly shaded blocks are trials that were lost and lightly shaded blocks

are trials located in the northern Natal and Central Mpumalanga region.

Trial No Location Comp. Species Fertilisation

age

Stem

s ha-

1

Altitu

de

(m)

Climate

zone Lithology

MRF 1 Canewoods A 055 E. grandis x

E. urophylla

4 yrs

6 mnths 1333 66 Sub-tropical Sand

MRF 2 Ixopo,

Sutton S 10 E. dunnii

8 yrs

3 mnths 1667 1055

Warm

temperate Dolerite

MRF 3 Ixopo,

Sutton E 14 E. dunnii 7 yrs 1667 1060

Warm

temperate Shale

MRF 4 Dukuduku C 23 E. grandis x

E. camaldulensis

8 yrs


MRF 5 Dukuduku D 12 E. grandis x

E camaldulensis

3 yrs


MRF 6a Bloemhoff, Dumbe B 013 E. dunnii 7 yrs 1667 1050

Warm

temperate Granite

MRF 7b Bloemhoff, Dumbe B 018 E. dunnii 7 yrs 1667 1050

Warm

temperate Granite

MRF 8 Watersmeet,

Iswepe C 137

E. grandis x

E. nitens 6 yrs 1667 1426 Cool temperate Granite

MRF 9 Babanango K 002 E. grandis/

E. nitens 6 yrs 1667 1319

Warm

temperate

Shale/

sandstone

MRF 10 Melmoth F 079 E. grandis 6 yrs

8 mnths 1667 1070

Warm

temperate Sandstone

MRF 11 Clan, Howick T 68 A E. grandis 6 yrs

6 mnths 1667 1000

Warm

temperate Shale

MRF 12 Makatweskop,

Paulpietersburg M 02

E. grandis x

E. nitens

6 yrs

2 mnths 1351 1326

Warm

temperate Shale

MRF 13 Riverbend, Ermelo H 04 E. nitens 6 yrs

10 mnths 1667 1493 Cool temperate Gabbro

MRF 14 Woodstock, Ermelo W 20 A E. nitens 7 yrs 1667 1600 Cool

temperate Granite

MRF 15 Windy Hill, Howick A 49 E. grandis 5 yrs

9 mnths 1667 850

Warm

temperate Sandstone

MRF 16 Highflats,

Ixopo H 21 E. dunnii

7 yrs

11 mnths 1667 882

Warm

temperate Tillite

a Lost to fire in November 2010 (15 month results reported).

b Lost to premature felling shortly after fertilisation.


Figure 1. Map of mid-rotation fertilisation eucalypt pulpwood trials

• Each site: Three treatments (Table 2) with a single replicate (n = 2)

• Each site consists of 16 x 16 outer trees and 6 x 6 inner measured trees.

• Granular fertiliser broadcast-applied in rainy season (summer).

• DBH measured at prior to fertiliser application and then six monthly thereafter.

Table 2. Fertiliser type and rates applied to the Control, NPK and NPK+ treatments for the Eucalyptus

pulpwood trials.

Nutrient Nutrient Source Application rate

(kg ha-1

) Control NPK NPK+

Nitrogen (N) LAN (28%) 300 no yes yes

Phosphorous (P) Single phosphate (10.5%) 200 no yes yes

Potassium (K) Potassium Chloride (50%) 100 no yes yes

Calcium (Ca) Calcium Nitrate (19%) 140 no no yes

Magnesium (Mg) Magnesium Sulphate (10%) 50 no no yes

Boron (B) Solubor (17%) 5 no no yes

Copper (Cu) Copper sulphate (25.6%) 5 no no yes

Zinc (Zn) Zinc Sulphate (35%) 2 no no yes


• The increases in basal area (basal area increment; BAI) at 15 months from time of fertilisation are

reported for all sites.

• Growth (BAI) shown relative to control treatment at each site to highlight relative responses.

• BAI compared using ANOVA.

Results

• No significant (p > 0.1) effect of fertilisation alone across sites (Table 3).

• Site (location) has highly significant (p < 0.001) effect on BAI at 15 months since time of

fertilisation.

• Some sites do show positive responses (10 of 15) to fertiliser when expressed relative to control

treatment (Figures 2 and 3).

• MRF 6, 8 and 9 were the most responsive (relative to respective control treatments) (Figures 2 and 3).

• The response to NPK and NPK+ is variable between sites (Figures 2 and 3).

Table 3. The basal area (BA (m2 ha

-1)) at the time fertilisation and 15 months after fertilisation, and the basal area

increase (BAI) for the 15 month growing period for the Control, NPK and NPK+ treatments for the mid-

rotation fertilisation of Eucalyptus pulpwood stands. Shaded blocks are trials located in the northern

Natal and Central Mpumalanga region.

MRF 1 2 3 4 5 6 8 9 10 11 12 13 14 15 16

Control

BA @ Fert 26.1 27.2 25.7 19.3 21.6 19.2 16.4 18.0 15.5 30.0 20.9 18.6 21.6 21.9 20.2

BA @ 15 month 30.8 29.0 27.8 20.1 26.3 21.1 17.9 20.5 17.0 33.7 25.5 21.2 25.5 24.4 21.4

BAI (15 month) 4.7 1.9 2.1 0.8 4.7 1.9 1.5 2.5 1.5 3.7 4.6 2.5 3.9 2.4 1.2

NPK

BA @ Fert 25.1 27.8 27.4 16.7 21.1 20.1 18.7 18.7 15.6 33.9 22.0 17.3 21.0 21.2 20.1

BA @ 15 month 29.6 29.6 29.6 17.6 25.1 22.8 20.7 21.5 17.1 38.0 27.2 19.6 25.2 23.3 21.4

BAI (15 month) 4.5 1.7 2.2 0.8 4.1 2.6 2.1 2.7 1.5 4.1 5.1 2.3 4.1 2.1 1.4

NPK+

BA @ Fert 25.9 27.8 25.9 18.0 18.6 17.5 16.2 18.6 16.8 29.4 21.7 19.1 20.7 23.1 20.4

BA @ 15 month 30.9 29.6 28.0 19.0 23.5 19.8 18.0 22.3 18.6 32.7 26.8 22.4 23.9 24.7 22.0

BAI (15 month) 5.0 1.8 2.0 0.9 4.9 2.4 1.8 3.8 1.8 3.3 5.1 3.3 3.2 1.6 1.6


-40

-30

-20

-10

0

10

20

30

40

50

60

1 2 3 4 5 6 8 9 10 11 12 13 14 15 16

Rel

ativ

e B

AI (

%)

MRF site

NPK

NPK+

0

1

2

3

4

5

6

0 1 2 3 4 5 6

BA

I fer

tilis

er (m

2h

a-1)

BAI control (m2 ha-1)

NPK NPK+ 1:1

Figure 2. The basal area increase (BAI) of the NPK and NPK+ treatments plotted against the control

treatment BAI at 15 months after mid-rotation application of fertiliser of Eucalyptus pulpwood

stands. Values above the 1:1 linear line indicate a positive response to a fertiliser treatment and

values near or below the line indicate small or “negative” response to fertiliser.

Figure 3. The difference in basal area increase (BAI) of the NPK and NPK+ treatments from the control

treatment, expressed relative to the control treatment (as a percentage) at 15 months after mid-

rotation fertilisation of eucalypt pulpwood stands. Positive and negative values indicate that a

treatment had a higher or lower BAI relative to the control treatment, respectively. This gives an

indication of the strength of the response relative to the control treatment at a particular site.

MRF 7 is not shown as it was prematurely felled.


Conclusions

• 15 month growth responses are inconclusive.

• Response to NPK and NPK+ is variable across sites.

• However, although the response was not significant, some sites may benefit from mid-rotation

fertilisation.

• Require final felling tree growth data and volumes to determine true benefit of mid-rotation

fertilisation.


Post thinning fertilisation of Pinus sawtimber

Table 4. A summary of trial details for all Pinus sawtimber post-thinning fertilisation trials implemented

since 2007. Shaded blocks are trials not reported in this presentation. Darkly shaded blocks are

trials that were lost and lightly shaded blocks are trials located in the northern Natal and Central

Mpumalanga region.

Trial No Location Comp. Species Age at

Fertilisation

oon

Stems

ha-1

Altitude

(m)

Climate

Zone Lithology

SLRF 1a

Tweefontein

Graskop N15 A P. elliottii

17 yrs

1 mnth 285 1360

Warm

temperate Shale

SLRF 2 Brooklands C 10 P. patula 16 yrs

3 mnths 276 1170

Warm

temperate Dolomite

SLRF 3b Braken

V007 &

V008 P. patula

22 yrs

1 mnth 310 1400

Cool

temperate

Shale/

Dolerite

SLRF 4 Luneberg

Paulpietersberg 007 A P. patula 19 yrs 309 1150

Warm

temperate Granite

SLRF 5 Watervaldrift

Iswepe 001 P. taeda 20 yrs 418 1400

Cool

temperate Granite

SLRF 6 Jessivale 13 B P. patula 15 yrs

9 mnths 258 1650

Cool

temperate

Granite/

Sandstone

SLRF 7 Weza

Singisi K 4 P. patula

17 yrs

9 mnths 239 1140

Cool

temperate Shale

SLRF 8 Sneezewood

Singisi B 50 P. patula

17 yrs

4 mnths 236 1480

Cool

temperate Dolerite

SLRF 9 Sneezewood

Singisi B 18 P. patula

17 yrs

4mnths 263 1420

Cool

temperate Mudstone

SLRF 10 Greytown T A P. elliottii 20 yrs

10 mnths 307 1197

Warm

temperate Sandstone

SLRF 11 Dargle K 8 A P. patula 17 yrs

6 mnths 290 1210

Cool

temperate Dolerite

SLRF 12 Nelshoogte

Highveld E 26 A P. patula

18 yrs

10 mnths 255 1372

Warm

temperate Granite

SLRF 13 Tweefontein

Lowveld A 68 A P. elliotii TBC 262 1160

Warm

temperate Dolerite

SLRF 14 Rynosterhoek

Sabie 06 C P. patula

15 yrs

9 mnths 332 1298

Warm

temperate Shale

SLRF 15c

Hendricksdal

Sabie J05 P. patula

15 yrs

2 mnths 278 1473

Cool

temperate Dolomite

SLRF 16c

London

Graskop A29 P. patula

15 yrs

2 mnths 333 1618

Cool

temperate Dolomite

SLRF 17c

Sarnia

Bulwer 17b P. patula

15 yrs

2 mnths 447 1252

Cool

temperate

Mudstone/

Shale

SLRF 18c Belfast E24 P. patula

19 yrs

10 mnths 275 1933

Cool

temperate Sandstone

SLRF 19c

Blyde

Graskop A39a P. patula

17 yrs

20 mnths 275 1570

Cool

temperate Quartzite

a Trial abandoned due to fire.

b Key treatment plots lost to lightning, so excluded from this analysis.

c New trials established in late 2010, data up to six months only.


Figure 4. Map of late-rotation fertilisation pine sawtimber trials.

• Each site: Eight treatments (Table 5) with no replication (n=1) – factorial application

• Each site consists of 13 x 21 outer trees and 7 x 15 inner measured trees (some variation where 7th

row extraction did not take place).

• Trees selectively removed from each plot to reduce inner and outer plot variance and plot variance

across a site.

• Typically there are between 20 – 25 trees in inner measured plot.

• Soil samples were collected prior to fertiliser application.

• Granular fertiliser was broadcast-applied in rainy season (summer).

• DBH was measured prior to fertiliser application and then annually in dry season thereafter.


Table 5. Fertiliser type and rates applied to the Control, N, P, K, NP, NK, PK and NPK treatments for the

Pinus sawtimber trials.

Nutrient Nutrient Source Application

rate (kg ha-1

) Control N P K NP NK PK NPK

Nitrogen (N) LAN (28%) 300 no yes no no yes yes no yes

Phosphorous

(P)

Single phosphate

(10.5%) 200 no no yes no yes no yes yes

Potassium (K) Potassium Chloride

(50%) 100 no no no yes no yes yes yes

• The increases in basal area (basal area increment; BAI) at 24 months from time of fertilisation are

reported for SLRF 2 and 4 to 14 (12 sites).

• SLRF 1 was lost to fire, SLRF 3 is not included due to lightning damage to key treatment plots and

SLRF 15 to 19 are not included as only six month data is available.

• For simplicity, only N, P, K and NPK treatments are reported here.

• Growth data was compared using ANOVA.

Results

• No overall significant (p > 0.7) effect of fertilisation across sites, but some sites show positive

responses (Table 6).

• The response to different fertiliser treatments at each site was variable (Figures 5 and 6).

• Eight sites had positive responses to N (4 >10%); seven sites had positive responses to P (5 > 10%),

seven sites had positive responses to K (4 >10%) and seven sites had positive responses to NPK (5 >

10%) – Figure 5

• Four sites had positive response to all treatments (SLRF 2, 12, 13 and 14) – Figures 5 and 6


Table 6. The basal area (BA (m2 ha

-1)) at the time fertilisation and 24 months after fertilisation, and the

basal area increase (BAI) for the 24 month growing period for the Control, N, P K and NPK

treatments for the post-thinning fertilisation of Pinus sawtimber stands. Shaded blocks are trials

located in the northern Natal and Central Mpumalanga region.

SLRF site 2 4 5 6 7 8 9 10 11 12 13 14

Control

BA @ Fert 20.0 20.9 31.1 16.3 25.4 22.2 21.6 23.0 25.7 16.4 24.1 17.2

BA @ 24 month 22.8 25.9 34.5 19.5 29.8 25.8 25.1 25.9 28.9 18.5 26.3 19.5

BAI (24 month) 2.8 5.0 3.4 3.2 4.4 3.6 3.5 2.9 3.2 2.1 2.2 2.3

N

BA @ Fert 19.3 25.3 28.3 17.0 26.9 21.0 22.8 23.3 19.8 21.1 21.4 17.5

BA @ 24 month 22.4 28.4 30.0 20.5 31.3 25.0 27.0 26.1 23.2 23.4 23.6 20.6

BAI (24 month) 3.1 3.1 1.7 3.5 4.3 4.0 4.2 2.8 3.6 2.3 2.2 3.1

P

BA @ Fert 19.0 22.0 31.9 16.8 26.0 18.9 20.8 23.2 20.3 22.7 23.0 14.2

BA @ 24 month 22.4 26.7 34.8 20.3 31.3 21.9 24.6 25.4 23.2 25.1 26.0 17.3

BAI (24 month) 3.4 4.7 2.9 3.5 5.3 3.0 3.8 2.2 2.9 2.4 3.0 3.1

K

BA @ Fert 19.8 22.3 31.2 17.9 25.7 22.5 19.8 25.4 24.1 19.9 23.3 16.4

BA @ 24 month 23.1 27.1 34.7 21.1 27.4 26.1 23.1 28.7 27.6 22.3 26.1 18.8

BAI (24 month) 3.3 4.8 3.6 3.1 1.7 3.6 3.3 3.3 3.5 2.4 2.8 2.4

NPK

BA @ Fert 20.6 20.8 31.2 18.9 26.5 18.4 21.2 23.7 26.2 17.5 20.6 17.2

BA @ 24 month 24.5 24.7 34.4 22.1 30.3 22.1 25.0 26.4 30.0 20.0 23.5 20.5

BAI (24 month) 3.9 3.9 3.2 3.2 3.8 3.7 3.8 2.6 3.8 2.5 2.8 3.4

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

BA

I fer

tilis

er (m

2h

a-1)

BAI control (m2 ha-1)

N P K NPK 1:1

Figure 5. The basal area increase (BAI) of the N, P, K and NPK plotted against the control treatment BAI at

24 months after final-thinning application of fertiliser of Pinus sawtimber stands. Values above

the 1:1 linear line indicate a positive response to a fertiliser treatment and values near or below

the line indicate small or negative response to fertiliser.


Figure 6. The difference in basal area increase (BAI) of the N, P, K and NPK treatments from the control

treatment, expressed relative to the control treatment (as a percentage) at 24 months after final-

thinning application of fertiliser of Pinus sawtimber stands. Positive and negative values indicate

that a treatment had a higher or lower BAI relative to the control treatment, respectively. This

gives an indication of the strength of the response relative to the control.

Conclusions

• 24 month growth responses suggest that some sites may respond beneficially to fertiliser.

• Variable responses to N, P, K and NPK may be due to nutrient imbalance or deficiencies.

• Determining final volume and wood quality properties will be important in assessing the true

value of positive responses to fertilisation.

Additional considerations for data interpretation

• Various factors may affect response to fertiliser:

o Short-term weather variability and its impacts;

o Correct site x species matching;

o Soil nutrient balance and dynamics (processes that control mobilisation and

immobilisation);

o Other factors – pest and diseases, genetic stock.

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

2 4 5 6 7 8 9 10 11 12 13 14

Rel

ativ

e B

AI (

%)

SLRF

N P K NPK


References

Allen HL. 1987. Forest fertilizers. Nutrient amendment, stand productivity, and environmental impact.

Journal of Forestry 85: 37 – 47.

Campion J and du Toit B. 2003. Impacts of fertiliser applied at second thinning on basal area growth of

Pinus patula in the Mpumalanga area. ICFR Bulletin Series 18/2003. Institute for Commercial

Forestry Research, Pietermaritzburg, South Africa.

Carlson C and Soko S. 2000. Impact of fertilization at first thinning on Pinus patula on basal area

increment in Mpumalanga. Southern African Forestry Journal 189: 35 – 45.

Crane WJB. 1981. Growth following fertilisation of thinned Pinus radiata stands near Canberra in south

– eastern Australia. Australian Forestry 44: 14 – 25.

Germishuizen I. 2007. A review of the current knowledge of the effects of re-fertilisation on the growth

of eucalypts. ICFR Bulletin Series 09/2007. Institute for Commercial Forestry Research,

Pietermaritzburg, South Africa.

Turner J, Knott JH and Lambert M. 1996. Fertilization of Pinus radiata plantations after thinning:

productivity gains. Australian Forestry 59: 7 – 21.

Acknowledgements

We would like to thank the many companies, foresters and managers, contractors and landowners for

making land available for these trials and with the assistance in establishing them.

We also would like to thanks Greg Fuller, Michael Buthelezi and Nkosinathi Kaptein for field support and

Janine Campion, Colin Smith, Ilaria Germishuizen and Alison Archibald for initiating the trial work. Sally

Upfold and Diana Rietz are thanked for commenting on draft version of this document.


Manual to Mechanised, why?

Danie Scheepers [email protected]

Bosbok Ontginning

Summary

Manual to Mechanised – Why?

• Diminishing rural workforce and more people reluctant to be employed in a high risk, hard work

environment.

• High cost of workman’s compensation and grower companies strive towards a low disabling

injury frequency rate.

• Very high theft rate of traditional harvesting equipment e.g. Chainsaws and logger components.

• Improving timber recovery on a resource already under pressure.

• Strive towards a more enviro-friendly harvesting system.

Which system?

If a decision must be made upon which harvesting system to use, there are several factors to take into

consideration like terrain, tree size, products and transport. For this specific application the systems

could be narrowed down to two:

• Scandinavian cut to length system: Consisting of a cut to length harvester infield and a

forwarder which delivers it to roadside depot.

• The American roadside processing system: With the roadside processing system, trees are being

felled by a feller buncher then extracted by a grapple skidder, processed on roadside by a

processor and the stacked on the depot by a loader or excavator based crane.

In this application the CTL system will:

• Have a reduced impact on soils;

• Have less double handling of products;

• Produce a evenly spread biomass making siviculture cheaper;

• Require smaller landing / depots;

• Ensure a more balanced system;

• Be less dependent by transport.

Initial Challenges

• Grower companies reluctant to engage in long-term contracts.

• No set harvester standards in a South African environment.

• No trained operators.

• Lack of specialised technical experience.

• Shortage of critical spares.


There were no “quick fix” solutions to any of these constraints. The machines were owner operated for

the first two years. The basic maintenance and repairs were also done ourselves, subsequently building

up a spare parts supply and technical experience.

Operators are being trained in house. After an operator is identified, he will work on a special second

“training” shift which take place after the daily production target has been reached. Operators get

trained on aspects from basic maintenance and repairs to site planning and creating bucking files.

High maintenance

Maintaining a fleet of specialised equipment means:

• Service according to a strict schedule;

• Budget on single shift;

• Make time for preventative maintenance;

• Fluid analysis on a regular basis;

• After each component failure, analyse and apply preventative action or adaption.

Team work

The dedication of the equipment supplier plays a very important role in the success of a mechanized

harvesting operation. He must assist his client to identify the right machines for a certain application

and keep them up to date with advancing technology and systems. Fast supply of critical spares is

crucial. An assessment on current machine conditions is also very important.

For a grower company, a good mechanised harvesting team will improve high value timber recovery,

reduce cost of maintenance on road infrastructure and silviculture, and ensure a steady flow of high

quality timber delivered on time to the mill.


Update on Leptocybe invasa, Thaumastocoris peregrinus and

Coryphodema tristis research

Izette Greyling*, Dawit Degefu and Marc Bouwer

*[email protected] Tree Protection Cooperative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI)

University of Pretoria

Summary

The increase in global trade and movement has led to an increase in pest and pathogen invasions. With

climate change this trend is set to continue and may also contribute to host shifts of already present

pest and pathogens. Insect pests pose a particular threat to the South African Forestry Industry.

These invading pests, whether non native pest introductions or host shifts by native insects, are often

very difficult to control. There is usually little information available and much research is needed before

effective control measures can be put into place. Biological control is usually a very important part

(sometimes the only option) in an integrated pest management programme.

Three insect pests that are particularly important to the forestry industry at present are Leptocybe

invasa (Eucalyptus gall wasp), Thaumastocoris peregrinus (Bronze bug) and Coryphodema tristis (Cossid

moth). Various research projects surrounding these pests have been and are being conducted at the

TPCP. In the cases of Leptocybe invasa and Thaumastocoris peregrinus, one of the main aims is to find

and establish suitable biocontrol agents for these pests.

The Cossid moth is different in that is thought to be a native pest that has undergone a host shift to

Eucalyptus nitens in the Mpumalanga Highveld region. To date this pest is only found in E. nitens, from

about four year old trees and older. In many ways this pest is an enigma. It has (besides museum

specimens) not been found in any indigenous trees It is restricted to E. nitens for the time being for

unknown reasons and no patterns to explain the host shift are evident at present. The pest is however,

spreading and attacking younger trees. Dawit Degefu, a PhD student from Ethiopia, is currently looking

into some of these factors including the ability of the Cossid moth to feed and infest other Eucalyptus

species. Investigations into monitoring and potential future control measures using pheromones are

also being conducted at FABI. Marc Bouwer, another PhD student is trying to identify possible

pheromones to use in monitoring experiments. This can be done through using techniques like Gas

chromatography coupled to Electroantennography.

More information on these and other forestry pests and pathogens are available on the FABI website at

www.fabinet.up.ac.za/tpcp. As always we also rely on foresters having eyes on their plantations and

reporting anything strange or new. Contact details are:

Field Extension: Jolanda Roux – [email protected]

Brett Hurley – [email protected] Izette Greyling – [email protected]

Diagnostic Clinic: Darryl Herron – [email protected]

Please also remember Treehealthnet, an email listserver for all who are interested in tree health in

South Africa. To subscribe please send an email to [email protected].


Effect of harvesting operations on a granite-derived soil on the growth of Pinus patula

Diana Rietz

[email protected] Institute for Commercial Forestry Research, PO Box 100281, Scottsville, 3209

Summary

Soil compaction has been found to negatively affect Pinus sp productivity in overseas plantations (e.g.

Murphy et al., 2009; Bulmer and Simpson, 2010). South African forestry soils that are particularly

susceptible to compaction are those with sandy loam, loam and sandy clay loam textures, derived from

sandstone, granite and tillite lithologies (Smith et al., 1997). The majority of commercial Pinus patula in

South Africa is grown in Mpumalanga, KwaZulu-Natal, and the Eastern Cape (DWAF, 2007), of which

32% of the area in these provinces under this species consists of sandstone and granite derived soils

(CSIR-ARC Consortium, 2000). Furthermore, these soils, and those under commercial forestry in South

Africa, do not possess properties that enable self-amelioration from the effects of compaction, i.e.

freeze-thaw or shrink-swell processes, and therefore compaction effects are cumulative (Warkotsch et

al., 1994; Smith, 1995; 2003). Soil compaction in commercial forestry plantations is often caused by

ground-based machinery during timber harvesting and extraction operations (Greacen and Sands, 1980;

Ares et al., 2005; Rietz et al., 2010). Despite this, no studies have been performed investigating the

effects of operations that cause soil compaction on soils with susceptible lithologies, coupled with the

effect on pine productivity in South Africa.

Materials and Methods

Therefore a study was designed that investigated the effect of timber extraction by grapple skidder,

cable skidder and timber truck on a granite derived soil and the next rotation of P. patula. Four

replicates of each treatment were imposed in February 2005 (Figure 1). Within each treatment plot,

areas varying in impact (low, moderate, high and very high) were identified, that resulted from the

number of passes made by the machinery, with areas closest to roadside experiencing the highest

impact (Figure 1). Thereafter harvest residues were burned, and the trial planted in November 2005 at a

spacing of 2.7 x 2.7 m.

Results

Soil bulk density, a measure of soil compaction, was found to be not significantly different between the

timber extraction treatments (Figure 2). However, significant differences were found in soil bulk density

between the extraction route and in the adjacent soil, as well as between the varying levels of impact

(Figure 2).

Regular tree growth (ground-line diameter or diameter at breast height (DBH) and height) and survival

measurements have been made to date (5.7 years of age). Tree growth up to two years of age was

assessed by biomass index. No significant differences in tree growth and survival were found between

timber extraction operations at any age, although there was a non-significant decrease in survival with

increasing degree of impact. However, level of impact frequently did have a significant effect on tree

growth, and these effects varied as the trees grew (Table 1). If tree productivity was assessed using

basal area, a significant negative effect of increasing impact was found (Figure 3).


The disparity in the trends for height/DBH and basal area results measured is due to increased mortality

with increasing level of impact. It is suggested that, during early growth, the increasing level of impact

caused poor growth and survival. As the trees grew it is likely that both soil and light resources became

limiting, and that the trees began to overcome the bulk density restrictions of the soil. The consequence

of this is that in the plots with poorer survival, the surviving trees could access more resources and thus

grew taller and larger than in the low impact plots that had a higher survival. Since the calculation of

basal area accounts for survival, it gives a more accurate estimate of the tree productivity in each plot.

The trend found here may, however, change over time as the trees grow larger.

These results indicate that early P. patula tree productivity is negatively affected by soil compaction on

granite-derived soils, although the persistence of this effect is not yet known. Early evidence indicates

that the type of operation carried out is less of a concern than the compactive effect of the operation

(dependent on machinery mass, number of passes, vibration, etc). The results show that mechanised

operations that lead to considerable soil compaction should be avoided on these soils when growing P.

patula. From a mechanised harvesting perspective, of particular risk is the merchandising deck of timber

extraction operations, and efforts need to be made to limit the size of area utilised for this practice.

While reductions in P. patula productivity at 5.5 years of age with current harvesting operations and

levels of impact may not seem substantial at this stage, these soils do not self-ameliorate from the

effects of compaction. Should ground-based mechanised operations on these sites continue, similar, or

greater levels of soil compaction as those achieved under very high impact in this study could be

attained across an entire compartment, unless some form of artificial amelioration is performed, e.g.

ripping. This would result in an almost nine per cent loss in basal area at 5.5 years of age, at which point,

the loss in productivity needs to be balanced against cost of ameliorative operations.

Timber truck Timber truck

Timber truck Timber truck

Cable skidder

Grapple skidder

Cable skidderCable skidder

Cable skidder

Grapple skidderGrapple skidder

Grapple skidder

Level of impact

Direction of extraction

LowLow ModerateModerate HighHigh Very highVery high

Figure 1: Layout of timber extraction treatments and associated levels of impacts at the harvesting impact trial

at Jessievale (from Smith, 2008; figure not to scale).


Figure 2: Effect of timber extraction treatments, position with respect to extraction route and degree of impact

on soil compaction as measured by soil bulk density (from Smith, 2008).

Table 1: Effect of degree of impact of timber extraction operations on P. patula growth, as measured initially

through mean biomass index (ground line diameter2 x height), and later through diameter at breast

height (DBH) and tree height. Values with different letters are significantly different (p < 0.05).

Tree age (years) Measurement Low Moderate High Very high

2.0 Biomass index (cm3) 3351

a 3827

b 4204

bc 4231

c

2.3 DBH (cm) 3.4 3.4 3.3 3.3

Height (m) 3.0 3.0 3.0 2.9

3.7 DBH (cm) 6.8 6.8 6.6 6.8

Height (m) 5.3 5.3 5.2 5.3

4.7 DBH (cm) 11.0

ab 11.0

ab 10.7

b 11.2

a

Height (m) 7.2 7.2 7.1 7.3

5.7 DBH (cm) 13.6

ab 13.5

ab 13.3

b 13.8

a

Height (m) 9.1ab

9.1ab

9.1b 9.2

a

1.0

1.1

1.2

1.3

1.4

1.5

Bu

lk d

ensi

ty (

Mg

m-3

)Harvesting operation Position Impact = distance

ba

aa

b

c


Figure 3: Effect of degree of impact of timber extraction operations on P. patula growth, as measured by basal

area. Values with different letters are significantly different (p < 0.05).

References

Ares A, Terry TA, Miller RE, Anderson HW and Flaming BL. 2005. Ground-based forest harvesting effects

on soil physical properties and Douglas-Fir Growth. Soil Science Society of America Journal 69:

1822-1833.

Bulmer CE and Simpson DG. 2010. Soil compaction reduced the growth of lodgepole pine and douglas fir

seedlings in raised beds after two growing seasons. Soil Science Society of America Journal 74:

2162-2174.

CSIR-ARC Consortium. 2000. National Landcover Database for South Africa (NLC 2000). 2000 edn., CSIR-

ARC Consortium.

DWAF. 2007. Report on Commercial Timber Resources and Primary Roundwood Processing in South

Africa. 2007. Department of Water Affairs and Forestry, Pretoria, South Africa.

Greacen EL and Sands R. 1980. Compaction of forest soils. A review. Australian Journal of Soil Research

18: 163-189.

Murphy G, Brownlie R, Kimberley, M and Beets P. 2009. Impacts of forest harvesting related soil

disturbance on end-of-rotation wood quality and quantity in a New Zealand radiata pine forest.

Silva Fennica 43: 147-160.

Rietz DN, Smith CW and Hughes JC. 2010. Effect of compaction and residue management on soil bulk

density and strength at two contrasting sites in KwaZulu-Natal. ICFR Bulletin Series 04/2010.

Institute for Commercial Forestry Research, Pietermaritzburg.

Smith CW. 1995. Assessing the Compaction Susceptibility of South African Forestry Soils. PhD. University

of Natal, Pietermaritzburg, South Africa. pp. 238.

Smith CW. 2003. Does soil compaction on harvesting extraction roads affect long-term productivity of

Eucalyptus plantations in Zululand, South Africa? Southern African Forestry Journal 199: 41-54.

Smith CW. 2008. Evaluating the effects of harvesting operations on early growth of Pinus patula: some

preliminary results. ICFR Technical Note 07/2008. Institute for Commercial Forestry Research,

Pietermaritzburg, South Africa.

0

2

4

6

8

10

12

14

16

18

20

2.3 3.7 4.7 5.7

Bas

al a

rea

(m2

ha-

1 )

Tree age (years)

Low

Moderate

High

Very high

a a ab b

a a a b

a a ab b

a b c d


Smith CW, Johnston MA and Lorentz S. 1997. Assessing the compaction susceptibility of South African

forestry soils. II. Soil properties affecting compactability and compressibility. Soil and Tillage

Research 43: 335-354.

Warkotsch PW, van Huyssteen L and Olsen GJ. 1994. Identification and quantification of soil compaction

due to various harvesting methods - a case study. South African Forestry Journal 170: 7-15.

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