Radiation Interception by Lowland Tropical Forest and Productivity of its Three Tree Species

The present study was conducted at Pasoh Forest Reserve, located in Negeri Sembilan Malaysia, at about 2°59'N and l02°18'E. The aims of the study were to determine the light environment in the lowland tropical forest and the light interception by the forest canopy and to understand the physiological responses of those selected species to different light in relation to their growth performances. Photon flux densities in different microsites and a clearing within a lowland evergreen tropical forest has been measured and compared between dry and rainy seasons under various of weather conditions. Measurements of PPD were monitored continuously at 5 min intervals over 14-29 day period using quantum sensors under the understorey, small gap, medium gap, big gap and open area. Vertical distribution of PFDs at different height levels of 52 m, 42 m, 33 m, 23 m, 19 m, 14 m, 7 m and on the forest floor were also measured. Daily average PFO, total daily PFO and average daily frequency distribution were analyzed. Daily total PFO in the open area, big gap, medium gap, small gap and understorey sites during the rainy season of November to January 1992 were 51-55, 17.8, 8.1. 8 and 4.51 %, of the daily total PFO recorded in the clearing, respectively. Daily total PFO in the big gap during the dry season was on the average 2 times lower than during the rainy season. In the clearing, high proportion of 5-min average was greater than 500 µmol m-2 S⁻¹, while in the medium, small gaps and understorey, were between 10 and 50 µmol m-l S⁻¹. On diurnal basis, there were high variations in PFO distributions at canopy height of 42 and 52 m during the midday. Mid canopy showed high variations in PFD during the study period. The highest daily total PPO recorded at 52 m was 50 mol m⁻² and the lowest value was found to be at the forest floor. The canopy of the emergent at 33 m height intercepted more than 50% of PFD. In situ growth experiments were carried out by establishing uniform sized seedlings of Shorea leprosula and Neobalanocarpus heimii in each micro site. Diurnal photosynthesis and growth performances were measured accordingly. Open area and big gap sites showed higher growth and photosynthetic rates. Photosynthetic light response curves of S. leprosula and Neobalanocarpus heimii seedlings grown inside the microsites were established. In addition, P-I response curves of N. heimii and Dipterocarpus sublamellatus canopy leaves were also established. The average photosynthetic light response parameters, a, P max, R and e which were calculated based on Thomley model. The a, Pmax, R and Bin canopy leaves of N. heimii and D

Ozone pollution and historical trends of surface background ozone level: a review

A literature survey was conducted to review the historical ozone data from background stations around the world to characterize background ozone levels and trends while also determining the reasons underlying such trends. Ozone pollution is regarded as a great concern nowadays because of its potential effects on human health and the environment especially vegetation. Historical increasing of ozone trends as reported ranged between 0.06 and 2.6% year with some of the largest increasing trend were observed at stations in Europe and Japan. For most stations, the trends were not consistent during the reporting period, but from the year 1970s until the mid 1980s, the trends are generally larger and steeper compared to the year 1990s. Sensitivity studies using chemical transport model were conducted to explain the rising trends in background ozone levels over the past decades

Phenological characteristics of reproduction and seed formation in Durio zibethinus Murray

Phenological characteristics during the reproductive processes of flower budding, flowering, fruiting and seed formation were investigated in a Durio zibethinus Murray tree growing in an experimental field of Universiti Putra Malaysia (UPM) in Selangor, Peninsular Malaysia. The survival curve showed that the relative fall rate of reproductive organs was lower at the mixed stages of flower budding, flowering and fruiting than at the early fruiting stage. The fall of flower buds commenced after the flower budding was completed. However, the falls of flowers and fruits occurred within a few days after the formation of flowering and fruiting. The periods of flower budding, flowering and fruiting were 34, 19 and 28 days, respectively. The fruit weight growth was approximated by a logistic equation, where the intrinsic growth rate varied from 0.419 to 0.794 week-1. The forming seeds germinated or possessed germination ability at the fruit growth stage where the fruit weight reached the asymptote of the logistic growth curve. Total numbers of emerged flower buds, flowers and fruits over the whole reproductive period were 1629, 1467 and 1412 per tree, respectively. The percentage of fruits with germination ability was estimated to be 1.2% of the number of fruiting ones

Ground-level ozone: a threat to rice crop in Muda irrigation area of Peninsular Malaysia.

It has long been recognized that pollutant gases cause significant impacts on crops and forests in both developed and developing countries. Ground-level ozone (O3) or better known as tropospheric ozone is recognised as the pollutant most likely to cause widespread crop damage. For this pollutant an AOT40 (accumulative O3 concentration above a threshold of 40 ppb) value causing 5% yield loss for all agricultural crops has been established as 3000 ppbh, which is applicable during daylight hours over a growing season (UN-ECE, 1996). In order to have a complete estimate of air pollution damage i.e., O3 to paddy plantation area, a dose-response, or yield-loss function have to be developed. In this study, data was gathered from tests in open-top chambers (OTCs), whereby four OTCs were fabricated; two of which were exposed to ambient air pollution (NF) of which ozone is the major perpetrator whilst the remaining were provided with clean air i.e. charcoal filtered air treatment (F). The response of a popular local rice cultivar, MR-219 to current ambient air pollution of which O3 is the overwhelming dominant pollutant was investigated for five successive seasons in Muda Irrigation Scheme Area (MADA); the largest rice growing area in Malaysia. The results of the study clearly indicate that at ozone concentrations even lower than the Malaysian air quality guidelines (60 ppb 8 hr mean) level, there exist a significant impact on the growth and yield of the popular rice cultivar MR-219. Even though weeds, diseases, and insect pests were absent, water and nutrients were in abundance, no adverse soil conditions, and that no extreme weather event such as typhoons occurs; the physiological, growth and development performances of rice plants exposed to ambient ozone were found to be significantly (P< 0.05) reduced by AOT40 compared to control rice plants in filtered chamber. This study discovered that the root was the most significantly affected component of MR-219 rice plant. Meanwhile, reproductive stage is the most vulnerable period of growth to ozone impact followed by grain filling and vegetative stages, respectively

Parking site selection management using Fuzzy logic and Multi Criteria Decision Making.

The construction of new service centers is very costly and the optimal site selection of these centers, one of the parameters for determining their degree of effectivencess, is of high importance. Public parkings are an example for these service centers. Population growth, sprawling of cities and increasing of vehicles result in heavy traffic and prolonged city trips.Utilizing public parkings can be regarded as an effective approach to abate traffic load in city centers, in that spaces designated for vehicles parking along the roads would be freed, and consequently the usable space of the roads would increase, which in turn would contribute to the smooth flow of traffic. In this paper, we describe an ideal method for parking site selection by the use of GIS, fuzzy logic and weighting criteria to determine proper parking sites. Suitable place for parking is selected for one of the high traffic regions of Esfahan city in Iran