Development of Diameter Distribution Yield Prediction Models for Simulation of Acacia Mangium Plantations

The purpose of this study is to develop diameter distribution yield prediction models for predicting probability density function parameters when age, spacing and number of trees per hectare planted are known. Five distributions, Weibull, Gamma, Johnson SB, Lognormal and Generalised Normal were compared in terms of their ability to model diameter data in uneven-aged and even-aged forest stands. The classical moments were applied as a measure of flexibility of the distribution in regard 'to their changes in shape. Diameter data were obtained from 16 uneven-aged stands of mixed timber species located at Bukit Lagong Forest Reserve, Kepong, Selangor and 14 even-aged stands of Acacia mangium located at Segaliud Lokan Project, Sandakan, Sabah. The stands were all plantations and the ages range from 2 to 22 years. The diameter data were fitted to the five distributions by the maximum likelihood estimation method. The Johnson SB distribution showed the best performance in terms of quality of fit to the diameter data based on relative ranking of the log likelihood criterion. The estimation of Johnson SB distribution was further investigated and the nonlinear regression method was proposed for the estimation of the SB parameters. This method was compared to five other estimation methods; namely the four percentile points method, Knoebel-Burkhart method, linear regression method, maximum likelihood method, and modified maximum likelihood method through simulation. The performance of the nonlinear regression was confirmed by using the real diameter data. Goodness-of-fit tests based on empirical distribution function (namely the Kolmogorov-Smimov statistic, Cramer-von Mises statistic and the Anderson-Darling statistic) were used in selecting the most superior parameter estimation method. The results suggested that the nonlinear regression method was superior for estimating parameters of the Johnson SB distribution for the diameter data. In order to simulate the stand characteristics, equations were developed for predicting average height, basal area per hectare, and number of trees per hectare surviving when age, spacing and number of trees per hectare planted were known. The predicted stand characteristics were then related to the estimated parameters of the Johnson SB and solving the resulting set of equations for the scale and shape parameters. This study revealed that the parameter prediction method yields reliable prediction equations of the stand characteristics, but the prediction equations of the scale and shape parameters suggested that further research is needed to improve the model

Fungal inoculation induces agarwood in young Aquilaria malaccensis trees in the nursery

Fungi are often used to induce agarwood in Aquilaria trees. This study was conducted to evaluate the effect of several fungi on agarwood formation over time in young Aquilaria malaccensis (Lam.) trees. Typical changes in the length and light intensity of the resulting discoloration were observed after three and six month periods following inoculation. Wood samples were observed microscopically and classified into several light intensity groups. The discoloration length was measured longitudinally. The duration after inoculation affected the mean of discoloration length: the 6-month old sample (1.70 cm) had a wider discoloration zone when compared to the 3-month old sample (1.17 cm). When measuring the discoloration intensity, a positive relationship with time was perceived. Digital images, captured using a camera-equipped microscope, revealed that wood samples collected after six months appeared to be 1.8-times darker than after three months. We concluded that time, not the species of any of the tested fungi, had significant effect on discoloration length and intensity. Gas chromatography/mass spectrometry (GCMS) analysis of the 6-month old sample yielded some important agarwood compounds such as benzylacetone, anisylacetone, guaiene and palustrol. This demonstrates that the tested fungi have the ability to induce agarwood formation in nursery A. malaccensis trees

Development of volume function for final felling of Pinus brutia Ten in Kurdistan Iraq

Planning for forest management depends upon the forest dynamics, which includes integration of all forest disciplines and understanding of forest resource characteristics including its growth dynamics. The forest growth and yield modelling can provide valuable information about forestry which can be used to determine harvest levels or allowable cut, and to analyze alternative stand treatments. Growth and yield models are generally used to predict the temporal development of forest stands. Knowledge of Diameter at Breast Height (DBH) and total tree height is fundamental to both developing and applying many growth and yield models [1]. Among the several available approaches in the yield prediction methodology, the multilevel model approach, which is a statistical technique, found to be commonly used in many fields of study for generating improvements in parameter estimation .A volume estimation of a forest stand is a good example. Volume estimation in the form of volume function and volume table has been widely used for many different purposes in forestry for more that hundred years including forest plantations and an inventory for timber harvesting. In view of the importance of these functions in forestry, this study was conducted with the main aim to develop a volume function for Pinus brutia Ten, which is a very common forest tree species planted in northern Iraq. The least squares method was used to fit eight unweighted volume equations including two logarithmic transformed equations and seven weighted forms of volume equations to volume data of a 25-30 years old Pinus brutia Ten plantation. The best fit equation was done using Furnival’s index

Abundance and distribution of climbers in a coastal hill forest in Perak, Malaysia.

Species diversity and density of all climbers were inventoried in five 1-hectare plots (at 45m to 350 m elevations) in a coastal hill forest of Pulau Pangkor in Perak. In addition, we analyzed pattern of community diversity using species richness and evenness. Total of 4901 climbers belonging to 45 species were recorded. Mean climber density was 870 stems per ha. Annonaceae, Connaraceae and Menispermaceae were the most species-rich plant families of climbers followed by Rubiaceae and Leguminosae. Twiners formed the bulk (64%) of climber types followed by hook climbers and tendril, while root climbers were rare. Results from Canonical Corresponding Analysis (CCA) indicate that altitude was the most important factor that influenced the abundance and distribution of climbers

Tree species composition and Structureofa Coastal Hill Forest in Pulau Pangkor, Malaysia.

Tree species composition and structure of a coastal hill forest in Sungai Pinang Permanent Forest Reserve in Pulau Pangkor at Perak was studied based on the data from five 1-hectare plots. All stems with a diameter at breast height (dbh) >5cm enumerated, identified and their height weremeasured. The mean stem density was 659 (stems ha-1), and a total of 45 families, 102 genera, 181 species, 3319 individuals were presented in the five 1-ha plot; this comprises 6.3% species, 19.2% genera and 42% families of the total tree taxa found in Peninsular Malaysia. Based on IVI, Vatica maingayi,Xanthophyllum affine,Vatica pauciflorawere the most dominant tree species. The families of Dipterocarpaceae, Polygalaceae,Guttiferae and Myrtaceae were among the most important families with high FIV. Based on dbh class, nearly 50% of the trees were distributed in the lower diameter class(5-15cm). According to heightlife-form categories, 53% of stems were belonged to small trees (7-15m). Species accumulation curve showedan asymptote at the third hectare

Tree species diversity of logged over forest at Tekai Tembeling Forest Reserve, Jerantut, Pahang.

The quantitative assessment of the hill logged-over forest at Tekai Tembeling Forest Reserve (TTFR), Jerantut, Pahang, Malaysia has never been investigated by the Forestry Department in the State of Pahang. This study investigated tree species diversity at 340-520 m asl. A one-ha (100 m × 100 m) study plot was established and trees with diameter at breast height (dbh) of 5.0 cm and above were measured. Results showed that a total of 1307 trees from 241 species were recorded from this 1-ha plot. Shorea curtisii had the highest relative abundance (0.039) followed by Swintonia floribunda (0.038) and Knema sp.l (0.034). Jackknife method for species richness estimated that 324.2 species present in the 100 quadrats. The regression equation to estimate species richness was lnŜ=0.91+0.49 ln (A) with r2=0.99% Simpson's index of diversity was 0.99 and Shannon-Weiner diversity (FT) was 6.99. Results also showed that Simpson's measure of evenness was 0.35 and Smith and Wilson's index of evenness was 0.50. These results suggested that species richness and diversity in logged-over forest of TTFR was high but the evenness was low. This was mainly because the species abundance within this plot comprised a variety of species and less species overlapping

Assessment of floristic composition of Kilim Geoforest Park, Langkawi, Malaysia.

The present study was carried out to analyze the species diversity and quantitative analysis of mangrove forest in three riverine ecosystems at River Kisap, River Ayer Hangat and River Kilim at Kilim Geoforest Park. One hundred plots, each of size 20 m × 20 m, were established at a distance of 250 m apart along the three rivers. Every existing species that occurred within the plot and trees of diameter at breast height of 1 cm and above were enumerated and identified. The data were analyzed for species richness, diversity and evenness. The species richness were computed based on the Jacknife method, species diversity index were calculated using Simpson’s Index, Shannon-Wiener Index and Brillouin’s Index. The evenness indexes were measured by Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness. A total of 11488 individual trees representing 58 species, 39 genus, and 23 families were recorded. The most abundant species was Rhizophora apiculata (3449) and Ceriops tagal (2060). The diversity results show that Shannon-Wiener, Simpson’s index of diversity and Brillouin index was high (2.0 to 3.0), (0.7 to 0.8), to (2.0 to 3.0) respectively and the evenness index however was low (0.1 to 0.2)

Community structure of trees in Ayer Hitam Forest Reserve, Puchong, Selangor, Malaysia

A study on community structure of trees >1cm Dbh was conducted in Ayer Hitam Forest Reserve (AHFR), Puchong Selangor, Malaysia. AHFR is one of the three remaining forests left in the Klang Valley and it is the only logged-over lowland Dipterocarp forest in urban settings. The aim of this study was to describe the tree community structure through structural attributes which are stem density, basal area (BA), aboveground biomass (AGB) and height distribution. A total of 7359 stem ha-130.57 m2 ha-1 (BA) and 232.7 t ha-1 (AGB) were estimated for 1-ha. The most abundant species for Dipterocarpaceae and Non-Dipterocarpaceae were Hopea sulcata Symington and Agrostistachys longifolia (Wight) Benth. (Euphorbiaceae), respectively. This study shows that AHFR is recovering but slowly and has good regeneration potential

Assessment of plant species diversity at Pasir Tengkorak Forest Reserve, Langkawi Island, Malaysia

Plant species diversity of a logged-over coastal forest with in the Pasir Tengkorak Forest Reserve, Langkawi Island, Malaysia was assessed by establishing a 1-ha plot. All plants above 1.0 cm dbh (diameter of a tree at breast height), or 4.5 feet above ground level, the accepted point of diameter measurement for most trees were enumerated. Species diversity was defined as a combination of species richness and evenness. The jackknife estimate and species- area curve were applied to estimate the species richness. It was estimated using Simpson’s index of diversity, Shannon-Weiner function and Brillouin index. Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness were also used to estimate species evenness. A total of 3414 individual trees representing 120 species, 81 genera and 31 families were recorded. Species with highest relative abundance were Swintonia sp1(0.12), Garcinia eugnifolia(0.09) and Syzygium sp1(0.05). The jackknife estimate of species richness was 132.9 and the regress ion equation to estimate species richness was LnSˆ=2.53 + 0.24 ln (A)with r2=96.0 %. Species diversity was high with Simpson’s index of diversity with a value of 0.96, while Shannon-Weiner index was 5.42 and Brillouin’s Index was 5.14. However, Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness were 0.264, 0.378, and 0.41 9, respectively. Results indicated that species richness and species diversity were high, but evenness was low in this logged-over coastal forest

Vegetation analysis of hill forest in Ulu Muda Forest Reserve, Baling, Kedah

This paper emphasize on the quantitative analysis of trees of unlogged hill forest in Ulu Muda Forest Reserve. Two plots of 1-hectare size were established within the forest area and divided to 100 10x10m quadrates. Only trees with dbh more or equal to 5 cm been observed. The species name, dbh and tree height were recorded from the trees. A total of 1825 of individual trees were observed in the two 1-hectare plots with 43 family and 236 species. The most dominant and diverse species is Mallotus kingii with 195 individuals in the 2ha plot, total basal area 3.17m2, relative basal area 5.87% and IVI 22.99. While the family Euphorbiaceae has the highest FVI (60.73). The most diverse plot is plot 2 with 976 individuals and 179 species