15 Means of tree survival for the four pine species (different letter index shows statistically different means at ps0.05, using Tukey's H8D test) 105 16 Results of the analysis of variance of tree survival with planting month. 27 Pearson's correlation coefficients analysis for BAlO, 8110, survival and site variables for each of the four pine species.
INTRODUCTION
Forest Plantations in Retrospect
Woodlands increased in importance with the colonization of the interior after 1836 (Owen and van der Zel, 2000). The early history of the closed canopy forests was one of uncontrolled exploitation and destruction.
OBJECTIVES AND HYPOTHESES
There is no difference in height and basal area growth for the four pine species.
CHARACTERISTICS OF THE STUDY AREA AND SITE FACTORS
Seasonal rainfall for the north-eastern part of the Eastern Cape Province (w=April - September; s=October - March). A very interesting study, comparing the climate of the study area with that of Piet Retief and Sabie (as traditional forest areas) and focusing on forestry potential, was carried out by Thackrah and Monnik (1998).
OTHER FACTORS POTENTIALLY INFLUENCING TIMBER PRODUCTIVITY
Old Land Syndrome including Soil Characteristics, Toxic Characteristics, Pests and Pathogens
Isolations were made from the roots of diseased trees as well as from soil in mangroves in different locations (Linde et al., 1994). After that, survival and actual growth of transplanted seedlings is of critical importance.
Growth of Pines at North East Cape Forests and their Timber Properties
- Weed Management
- Fertilization
No abnormally high amounts of extractives could be detected in any of the wood samples. Because almost all NECF estates had been corn or cattle ranches before they were planted. Even with the ridging work of the disc ploughs, the texture of the soil is often not suitable for planting trees.
Using the deep rip and ridge technique in wet soils resulted in degradation of the soil in front of the plow blade. Because the soil was plastic, the effect of under-polluting was to create a deep but narrow groove through the soil. AshhecLay-:loam is wet. The edges of the grooves are smeared with wet clay. A smooth wall like this is almost impenetrable to trees Joots (Darrowr 1997). Because the areas prepared for planting each year were very large, weed control was behind schedule.
In the first years, therefore, all the seedlings used in the project were bought from different suppliers. Strict control was placed on the timing of the delivery of seedlings to the estate for planting.
Top Die-back
Thus, there was a natural trade-off between capital expenditure on land and the quality of potential afforestation information available to support the acquisition decision-making process, this was further complicated by the unique geology and climate parameters associated with the Eastern Cape as evidenced by subsequent ongoing research. During 1993, a reassessment of NECF lands found that 24 000 ha of the original acquired area was unsuitable for afforestation due to low rainfall, inaccessibility, shallow soils or steep slopes (Botha, 1996). To investigate this phenomenon, Fyfield et al. 1998) characterized the macro and microclimate in some detail; the response of the trees to an applied nutrient treatment was determined; both soil and tree water status were determined as a function of water supply; and tree growth and shape were monitored at an experimental site in Sonsbeek, during the period July 1997 to March 1998.
The region experiences lower minimum temperatures than other forest areas in South Africa and as such can be classified as marginal in terms of the recommended temperature standards for the cultivation of P. A high frequency of very cold nights, when temperatures drop below -5 °C and the corresponding warm days occur during winter (Fyfield et al., 1998). The drier the soil was during this critical period, the more severe the water stress was (Fyfield et al., 1998).
Copper (Cu), Zinc (Zn) and Molikolemin (Mo) were deficient in the samples taken at the start. However, copper (Cu) was deficient only in the foliage of the trees in the control plots, indicating that the fertilizer application was effective in this case (Fyfield et al., 1998).
Road Construction
After fertilization, Zinc (Zn) and Molikolemni (Mo) were still lacking in leaves, indicating that the fertilizer application was ineffective.
Socio-Economic Parameters
Drought, Wind, Soil Temperature, Snow and Hail
The most common form of snow damage to forest plantations in South Africa is stem breakage, but trees can also be bent or even uprooted. Trees growing in sheltered valleys and on the steep sides of ridges and hilltops are more prone to snow damage than those located on exposed ridges and hillsides. Snow damage depends on the interaction of meteorological conditions, topography, as well as certain characteristics of trees and stands.
Potential risk of snow damage to commercial forest plantations in relation to altitude for the KwaZulu-Natal region (Kunz and Gardiner, 2001). Altitude is not the only factor that affects snow depth and therefore the risk of snow damage. The effect of slope, combined with wind direction, means that trees located on steep south-facing slopes should experience the most snow damage (and steep north-facing slopes . the least).
Stands with wider spacing or large stand openings are at greater risk of snow damage due to increased wind loads in the sparse stands (Davidson, 1989). For the same reason, heavily thinned stands would also be more vulnerable to snow damage.
SAMPLING METHODS
This requires measuring the horizontal distance between the operator and the tree using an optical range finder and the angles between the horizontal and the top or bottom of the tree. The angle between the operator and the top of the tree should be less than 45 degrees, as this reduces parallax. Average stand height was defined as the estimated tree height with average basal area.
Due to the nonlinearity of the relationship, both variables were transformed with log (height) as the response variable and the inverse of DBH as the predictor. Furthermore, the dominant height was defined as the regression height of the 20% thickest trees recorded in each compartment (Bredenkamp and van Laar, 1993). The area of the pie chart was therefore calculated using the conventional pie area formula.
One member of the team defined the perimeter of the plots with the rangefinder, while the other member measured the DBH of each tree falling within the plot (Figure 7). The DBH calipers were always held perpendicular to the longitudinal axis of the log.
THE SURVIVAL OF FOUR PINE SPECIES
Methods
The following hypotheses were examined: i) Ho: There is no difference in the survival of the four pine species. There is no difference in the survival of the four pine species planted in different months. It was also investigated whether the planting month had any influence on the survival of the different species.
After an arcsine transformation of tree survival, testing for normality and homogeneity of variance, survival of each species was subjected to a one-way analysis of variance, considering planting month as treatment. The result of the analysis of variance of the survival data is shown in Table 14 and confirmed the chi-square results. Results of analysis of variance in arcsine-transformed survival date for the four pine species.
Mean tree survival for the four pine species (different letter subscript indicates statistically different means at p~0.05, using Tukey's HSD Test). Results of analysis of variance of tree survival with month of planting as treatment, for all pine species.
Conclusion
In conclusion, this analysis confirmed the importance of species selection and the subsequent economic importance of site-specific species selection.
THE RELATIONSHIP BETWEEN THE GROWTH OF PINES AND SITE CONDITIONS
- Results and Discussion
- Conclusion Survival
CL_TOP_MIN = average minimum percentage of clay in the A-horizon measured at 30 cm intervals from 0 to 1.5 m, this reflects the lower tolerance level for the broken interval. CL_TOP_MAX = Average maximum percentage of clay in the A-horizon measured in 30 cm intervals from 0 to 1.5 m. CAY E MIN = Average minimum percentage of clay in the E-horizon, measured in 30 cm intervals from 0 to 1.5 m.
CLAY E MAX = The average maximum clay percentage in the E horizon, measured at 30 cm intervals from 0 to 1.5 m. CL_SUB_MAX = The average maximum clay percentage in the B horizon, measured at 30 cm intervals from 0 to 1.5 m, this reflects the higher tolerance level for the reflected interval. Pearson's correlation coefficient of the PROC CORR procedure (SAS Institute Inc., 2001) was used for the correlation analysis.
In the first stage, growth data were correlated with location data for all species combined. The effect of percentage of clay in the E horizon (CLAY_E_MIN) in SA10 for all species (model 3) was negative.
RECOMMENDATIONS FOR FURTHER RESEARCH
HERBERT, M.A., and SCHONAU, A.P.G., (1989), Fertilization of Commercial Forest Species in Southern Africa: Research Progress and Problems (Part I). HERBERT, M.A., and SCHONAU, A.P.G., (1989), Fertilizing commercial forest species in Southern Africa: Research Progress and Problems (Part 11). LOUW, P.J.E., MALAN, C., VILJOEN, O.C., and VAN HUYSSTEEN, I., (1994), Report on a preliminary investigation into the old-field syndrome at selected sites in the North-Eastern Cape forests, Institute for Vine and Oenology, Stellenbosch, 35 p.
PIENAAR, L.V., and SHIVER, B.D., (1981), Survival functions of site-prepared slash pine plantations in the flatwoods of Georgia and northern Florida. RICHARDSON, D.M., and KRUGER, P.J., (1990), Water relations and photosynthetic characteristics of selected trees and scrub in riparian and hillslope habitats in the South Western Cape Province, South Africa. SCHOEMAN, J.P., MARWICK, P.C., and VAN ULL, (1977), The mechanical properties of wood with special reference to those grown in the Republic of South Africa.
SCHONAU, AP.G., and SCHULZE, RE, (1984), Climatic and altitudinal criteria for commercial forestry with special reference to Natal, S. SWAIN, T-L, GARDNER, RAW., and CHIAPPERO, C.C., (2000), Final results of three ICFR Eucalyptus dunnii trials in KwaZulu-Natal, South Africa.
