A study was conducted by using stratified haphazard sampling at secondary forest at Taman Alam, Kuala Selangor and primary lowland dipterocarp forest at Gombak Reserve. This study aimed to compare the distribution of different types of species and plants and also to investigate the links between abiotic and biotic factors with the density of species in both secondary forest and primary lowland dipterocarp forest. The secondary forest had higher number of species (1214 species) compared to the primary lowland dipterocarp forest at Gombak which only contained 248 species. In the secondary forest, the soil was grey clay whereas at Gombak the soil was clay and coarse sand and it was yellow-brownish in colour. The salinity obtained from the secondary forest was 2.1‰ higher than primary forest which was zero because of the location of the secondary forest was nearer to the seawater that provided salts.The percentage of canopy cover and leaf litter cover were higher in primary lowland dipterocarp and the percentage of ground cover was higher in the secondary forest. The species that was highly abundant in the secondary forest were Asystasia intrusa (herb), Stenoclaena palustris(fern), Nephrolepis biserrata (fern) whereas the primary lowland dipterocarp rich in Tectaria semipinnata (fern), Licuala sp (fan palm), Hill Coconut, and etc.
Secondary forest is formed as consequence of human activities on forest lands. In this study, the secondary forest of Kuala Selangor Taman Alam and the primary lowland dipterocarp forest at Gombak Reserve were studied. Originally, the Kuala Selangor Taman Alam was mostly developed with mangrove ecosystem extended along the coastline of the Selangor river estuary. In the 1960's, redevelopment was marked to this park and an embankment was built in order to drain the swampland habitats and reduce flooding of Kuala Selangor village. Then, the area had an extreme logging and occupied by secondary growth species including Acacia trees, creepers, and mangrove ferns and strangling figs. This area had now become a secondary forest and full with a lot of species such as Stenoclaena palustris.
The primary lowland dipterocarp forest constitute to the primary forest of the plains, undulating land and about up to 300m altitude. Commonly, high proportions of emergent and dominant strata are formed from dipterocarps (Krishnapillay, 2004). Dipterocarp species is suitable to grow in the equatorial climate and temperature of Malaysia which is 25ºC to 27 ºC (Manokaran & Konchummen, 1992). This forest has diverse forest types and species up to 85% canopy layer and it has two-winged fruit structure mostly abundant with dipterocarpaceae family (Appanah, 1993). Lowland dipterocarp forest constitute mostly in Borneo, Sumatra, Java, and Peninsular of Malaysia.
The purpose of this study was to differentiate between these two types of forests in the form of its structure and biodiversity and also to determine the links between biotic and abiotic factors. In order to study the individual plants distribution and the types of plants present in both forests, many studies had been performed. For instance, Manokaran and Kochummen (1992) performed a study in the primary lowland and hill dipterocarp forest to investigate the growth of trees by calculating the diameter breat height (DBH) for each species.