Sap flow study on two different diameter sizes of Tectona grandis

Sap flow pattern of Tectona grandis planted at lowland forest assessed. This study aimed to determine the sap movement of two different diameter sizes T. grandis. Two sizes selected were 16 and 38 cm in diameter at breast height (dbh). Sap flow meter (SFM) used to assess the sap velocity rates at the interval of 30 min within 24 h for 15 days. Diurnal sap flow of T. grandis shows that mean velocity is high during day time compared night time. Small diameter has high sap flow compared to that of bigger diameter. A flow rates was high at the inner layer and less at outer layer for smaller tree. The variation was vice versa when the tree was getting bigger. Variations in sap flow of T. grandis characterized by several environmental factors. It was found that size contribute in the differed sap flow of T. grandis

Throughfall at an abandoned skid trail in a tropical rain forest in Peninsular Malaysia

Knowledge of throughfall at abandoned skid trails in tropical forests is extremely scarce. Thus, throughfall was measured using 120 storage rain gauges set on a skid trail left abandoned 41 years after forest harvesting in the Bukit Tarek Experimental Watershed (BTEW) in Peninsular Malaysia. All trees of ≥ 1 m height in the plot were identified to the species level, and their diameter at breast height (DBH) and height were measured. Vegetation along the skid trail comprises trees with smaller DBH (0.2-31.0 cm, with a mean of 2.0 cm) and shorter height (1.0-20.0 m, with a mean of 2.8 m) than those in the regenerated secondary forests of BTEW. The diversity (i.e. 43 families, 131 species) at the skid trail was similar to that in an old tropical forest at BTEW. The ratio of throughfall to gross rainfall (Th/Rg) for 84 rain events ranged from 27.4% to 204.7% with a mean and standard deviation of 98.1% and 33.2%, respectively. We found that a considerable amount of rainwater dropped under bertam (i.e. Eugeissona tristis) and rattan (i.e. Daemonorops callicarpa, Calamus insignis) vegetation. The Th/Rg ratio weakly correlated with canopy openness. The mean Th/Rg ratio is the largest mean ratio ever reported for forests in Malaysia

Influence of Plantation Establishment on Discharge Characteristics in a Small Catchment of Tropical Forest

A study was conducted on the impact of forest clearance on discharge from newly established Hopea odorata plantations catchment (14.4 ha). The stands were two years old when this study commenced in year 2006 and the data collection was carried out for two years. The forested catchment (C3) was clear-cut during the preparation of the forest plantation and catchment C1 was left undisturbed. Discharge and rainfall were measured continuously for two years. The discharge measured from years 1997 to 2003 was used also to determine the water yield before and after forest clear-cut. This study showed that the plantation catchment is more responsive to storm with higher total water yield than in the forested catchment. The effect of forest clear cutting to discharge was clearly shown by the increment in the amount following the clear-cut activities and time taken for the recovery of the discharge back to its original state was almost three years. The peak discharge in C3 also was affected in which the biggest change was obtained during the forest clear-cutting period compared with during calibration and after clearing periods. This study is useful as basis for improving the existing guidelines on forest plantation establishment

Assessment of values and trends in coarse spatial resolution NDVI datasets in Southeast Asia landscapes

Normalized difference vegetation index (NDVI) has been widely applied for monitoring vegetation dynamics. However, NDVI values are known to be profoundly affected by various external factors. In this study, the variation of NDVI values and trends among the several long-term NDVI datasets with resolution of 1, 4 and 8 km were assessed to understand the differences between the available datasets. The assessment items were 1) Pearson’s correlation coefficient, 2) trend map and breakpoint spatial similarities and 3) comparison of NDVI from Landsat and Flux tower in 2007–2015. The comparison revealed a maximum correlation coefficient of 0.67 among NDVI datasets and average spatial similarity of 37.2% among the trend maps estimated from NDVI datasets. Furthermore, there was a possibility of having significantly opposite trends between two trend maps from different NDVI products. Comparisons with NDVI from vegetation pixel in Landsat 5 TM and 8 OLI resulted in the R2 between 0.06 and 0.68 and RMSE of 0.07–0.2, while comparison with NDVI from flux tower data yielded the RMSE of 0.04–0.41, although the R2 was relatively weak at 0–0.18. Our study highlights the possibility of differences among NDVI datasets, and suggests that these differences should be reconciled especially in time-series analysis

A preliminary investigation on water quality of water courses in oil palm smallholdings converted from peat swamp and mangrove forests

Oil palm smallholdings had been extensively established at the expense of peat swamp or mangrove forests. This study was conducted at peat swamp forest converted (PF) and mangrove forest-converted (MF) sites in Tanjung Karang, Selangor. Dissolved oxygen (DO), pH, temperature, electric conductivity (EC), turbidity, salinity and total dissolved solids (TDS) were measured with corresponding water levels at 25 stations in each study site. Kruskal-Wallis Analysis of Variance was used to compare the means of each water quality parameter for both study sites while the Spearman’s correlation tests were used to detect any collinearity between parameters. The preliminary results indicated that EC, salinity, pH and TDS were significantly higher in MF compared to PF (Kruskal Wallis p < 0.001) due to the high salt concentration in MF and low pH in PF. Although both study sites were converted to oil palm about 50 years ago, the water quality measured suggest that the levels were much influenced by the original land cover

A preliminary investigation on water birds and their relation with flood-control drain water quality in oil palm smallholdings

Human modified landscapes such as oil palm planted areas can sustain water bird communities. This study aimed at quantifying the diversity of water birds at aquatic habitats in oil palm smallholdings in Tanjung Karang, Selangor. Seven water quality characteristics were measured, namely, pH, dissolved oxygen (DO), total dissolved substance (TDS), water temperature, salinity, conductivity and turbidity. Ground vegetation cover, stream width, water level and stream velocity were also measured. Twenty five line transects were established within the peat swamp forest-converted (PF) and mangrove forest–converted (MF) oil palm smallholdings. Between March and April 2013, a total of 315 water birds (seven species - six residents and one migratory species) were recorded. The species diversity of water birds was higher in MF than PF. At PF, species richness increased with water level and TDS, but decreased with salinity. At MF, species richness decreased with water level and turbidity. Flood-control drains and water quality are important for water bird conservation in oil palm planted areas