Abstract. Wasli ME, Ambun DB, Kalu M, Sidi M, Nahrawi H, Elias H. 2020. Assessment on the growth performance of planted Dryobalanops beccarii at reforestation sites after implementation of selective girdling. Biodiversitas 21: 1880-1889. This study was conducted to evaluate the growth performance of planted Dryobalanops beccarii Dyer at reforestation sites after silvicultural practices in Gunung Apeng National Park (GANP), Sarawak. The assessed area was planted with D. beccarii in 2005 and undergo silvicultural treatment by understory clearing which implemented annually. Due to the suppressed growth rate of the planted trees, an additional silvicultural treatment, the selective girdling on selected pioneer species, was implemented once, in 2012. In this study, study plots with two treatments were established: T1: understory clearing only (control plot), and T2: additional selective girdling of existing pioneer species in addition to the understory clearing practice applied in T1. The growth performance of the planted D. beccarii in terms of DBH, height, survival and mean annual increments in diameter (MaiD) and height (MaiH) were assessed and monitored at the initial stage when the selective girdling treatment was applied and 4, 24, 36, 48, 60 and 72 months after girdling. Our findings showed that the survival rates of planted trees at 72 months under treatments T1 and T2 were 82.9% and 79.2%, respectively. The average tree DBH in T2 was significantly higher than that in T1, and the average tree DBH values for T1 and T2 were 7.5 cm and 9.4 cm, respectively. The average tree heights for T1 and T2 were 8.3 m and 9.2 m, respectively. In terms of the mean annual increments in height (MaiH) and diameter (MaiD), those in T2 were significantly higher than those in T1. Our findings indicated that T2 started to show better growth performance than T1 after a period of 36 months. In conclusion, the additional silvicultural treatment by selective girdling at the reforestation site had a long-term, progressive effect on the growth performance of the planted trees.
Abstract. Sidi MB, Wasli ME, Polly E, Jaffar ANNM, Kalu M, Sani H, Nahrawi H, Elias H, Omar D. 2021. Short Communication: Incidence of insect pest on planted Shorea macrophylla at reforestation sites in Gunung Apeng National Park, Sarawak, Malaysia. Biodiversitas 22: 5162-5168. Incidence of insect pest in Shorea macrophylla (de Vriese) P.S. Ashton had critical foliage damage in mono planting technique. The main objectives were to assess the foliage damage intensity of planted S. macrophylla by age stands and type of foliage damage. The insect pest attacks the foliage of S. macrophylla was determined. The study site was located at Gunung Apeng National Park (GANP), Sarawak, Malaysia, with planted S. macrophylla in enrichment planting at different years (planted in 2008, 2009, 2010, and 2011 for age stand 6, 5, 4, and 3, respectively). The results showed that the degree of foliage damage decreases with the age stand of S. macrophylla tree. Therefore, foliage damage was suspected to be caused by insect pests. Among the common foliage damages observed was "hole damage" caused by insect order Lepidoptera. Although foliage damage was significant, the severity of the damage will "heal" as the age stand increases. Further investigation on other possible causes of these pest attacks should be initiated to find solutions that may hasten the growth of planted S. macrophylla for forest restoration.
The yellow rice stem borer, Scirpophaga incertulas (Walker) is a prevalent pest in paddy fields worldwide. In Sarawak, a survey on pest of paddy carried out from 2009 to 2011 covering 166 paddy fields revealed that rice stem borers caused 11.4% of total paddy damage. In order to reduce the damage, identifying resistance paddy variety is crucial. The objective of this study was to screen Sarawak paddy landraces with resistance to S. incertulas. Twelve Sarawak paddy landraces were selected randomly for this study. Antixenosis resistance screening was performed in aquariums (60 x 28 x 33 cm). Three replications of one-month-old seedlings were randomly arranged in aquarium and exposed to adult S. incertulas. The number and position of egg mass on each plant were recorded. Egg mass abnormalities were also observed. For antibiosis, rice culms of two-month old seedlings from each landrace were infested with larvae. The length of surviving larvae from five rice culms was measured. The experiment revealed variations in landrace of preference for ovipositing. Among the twelve Sarawak paddy landraces, Kanowit was more preferred by S. incertulas for ovipositing in comparison to other paddy landraces suggesting susceptibility towards the pest. Abaxial leaf surface was the preferred oviposition site. There was no clear antibiosis response of the paddy landraces towards S. incertulas larvae in this study.
Soil Organic Carbon (SOC) has long been known as an indicator of soil health. This study aims to estimate the amount of SOC at Takasago-UNIMAS Educational Forest, a post-construction site, for forest rehabilitation. Since 2018, rehabilitation approaches have been conducted in the UNIMAS campus to restore these land areas via enrichment planting. The estimation of SOC was conducted at three sites; Secondary Forest (SF), Enrichment Planting site (2018) (EP18) and Enrichment Planting site (2019) (EP19). In each study plot, soil samples from different depths were collected for further analysis. Our findings showed that the soils in SF portray the highest amount of Total Carbon and Nitrogen, suggesting that this site may not have been considerably affected due to the past land use. Moreover, the estimation of SOC in all sites indicated that SF shows the highest mean at 2007.0 g/m2 at the soil depth of 0-30cm, followed by EP18 and EP19. From the estimation, it can be concluded that although the period of establishment in EP18 and EP19 may have contributed to the lower SOC as compared to SF, the SOC estimation from this study could be a value-added option in determining the state of soil recovery and, possibly, the effectiveness of enrichment planting for forest rehabilitation.
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