Effects of Soil Compaction and Relative Light Intensity on Survival and Growth Performance of Planted Shorea macrophylla (de Vriese) in Riparian Forest along Kayan Ulu River, Sarawak, Malaysia

A study was conducted in riparian forest along Kayan Ulu River, Sarawak, Malaysia, to investigate the effects of soil compaction and relative light intensity (RLI) on survival and growth performance of planted Shorea macrophylla. The study sites were stands reforested in different years (1996: SPD96; 1997: SPD97; 1998: SPD98; 1999: SPD99). The survival, growth performance, soil compaction, and RLI were measured. SPD96 trees had the highest survival (84%) and showed the most favourable growth. Average height, mean annual increment in height, and RLI were highest in SPD97 while mean annual increment in volume was highest in SPD98. Soil compaction in SPD98 and SPD99 was higher as compared to SPD96 and SPD97. This was due to the compacted soils caused by anthropogenic activities and natural causes (wet soils) in riparian forest along Kayan Ulu River at shallow depth. High survival and favourable growth performance of S. macrophylla were influenced by the edaphic factor with special reference to less compacted soils and high RLI. Stepwise multiple regression demonstrated significant effects of soil penetration resistance at the depth of 0-30 cm and RLI on mean annual increment in diameter. Further ecological studies on other environmental factors should be implemented to draw up a Dipterocarp planting scheme for the future restoration of riparian ecosystem.

Accurate Measurement of Photoelasticity Based on Digital Camera

Photoelastic analyses have been successfully conducted by several researchers and many equations based on digital images were presented. Although these equations were all derived using the light intensity emitted from the analyzer, pixel values of the digital image were actually used in the real calculations. In this paper, we proposed that relative light intensity should be used instead for more accurate photoelastic analysis. Real isochromatic images were generated based on relative light intensity as well as pixel value. The analysis showed that the proposed approach can obtain better result than that of the previous method.

Natural regeneration in a beech-dominated forest managed by close-to-nature principles — a gap cutting based experiment

European beech ( Fagus sylvatica L.) is increasingly managed by close-to-nature principles, mimicking the gap dynamics of seminatural forests. The prime aim of this study was to analyse natural regeneration reliability under favourable conditions in newly formed gaps. A total of 12 gaps were created by felling three canopy trees for each gap: six gaps in each of the two winters 1996–1997 and 1997–1998. One-half of the gaps were fenced against deer. We recorded advance regeneration density (1997), regeneration density and height (1997–2002), relative light intensity (1997–2002), and volumetric soil moisture content (1997–2002). We also studied the effect of year of establishment, fenced versus unfenced, and position within gap on regeneration. Three or 4 years after gap formation, most gaps had nearly closed. Response of European beech, European ash ( Fraxinus excelsior L. ), and sycamore maple ( Acer pseudoplatanus L.) regeneration to gap formation was limited, and few seedlings were added to the advance regeneration pool during the study period. Other factors, such as relative light intensity, soil moisture, fencing, year of establishment, and position within gaps, all had rather low effects. Thus, the presence of advance regeneration appeared to be a key factor in explaining regeneration patterns in artificially created gaps.

Beech sapling architecture following small and medium gap disturbances in silver fir-beech old-growth forests in Slovenia

The objective of our research was to examine the effect of canopy shading on beech sapling architecture in the oldgrowth silver fir-beech forests of Pecka and Rajhenavski Rog. In August 2003 we sampled one plot (352 m2) in a large gap in Pecka, which was a result of a strong windstorm in 1983, and eight small gaps (26–78 m2) with similar sapling heights (3.8–8 m). A ground view of each gap was drawn including the characteristics of gap border trees and the density of separate sapling layers was recorded. The height and diameter were measured for each sapling, as well as the following quality characteristics on selected dominant saplings: width of the crown,number of larger branches and knots (>1/3 DBH), intensity of stem bending, deviation from vertical growth, number of terminal shoots, and the type of damage. The results show a negative effect of high canopy shading (estimated relative light intensity was below 5%) on the architectural quality of saplings. A lower overall density of saplings, greater intensity of bending and deviation from vertical growth, a shorter stem length without branches, a larger number of saplings with two terminal shoots, and a larger number of damaged saplings were observed in small gaps.