Above ground biomass-carbon partitioning, storage and sequestration in a rehabilitated forest, Bintulu, Sarawak, Malaysia

Forest degradation and deforestation are some of the major global concerns as it can reduce forest carbon storage and sequestration capacity. Forest rehabilitation on degraded forest areas has the potential to improve carbon stock, hence mitigate greenhouse gases emission. However, the carbon storage and sequestration potential in a rehabilitated tropical forest remains unclear due to the lack of information. This paper reports an initiative to estimate biomass-carbon partitioning, storage and sequestration in a rehabilitated forest. The study site was at the UPM-Mitsubishi Corporation Forest Rehabilitation Project, UPM Bintulu Sarawak Campus, Bintulu, Sarawak. A plot of 20 × 20 m2 was established each in site 1991 (Plot 1991), 1999 (Plot 1999) and 2008 (Plot 2008). An adjacent natural regenerating secondary forest plot (Plot NF) was also established for comparison purposes. The results showed that the contribution of tree component biomass/carbon to total biomass/carbon was in the order of main stem > branch > leaf. As most of the trees were concentrated in diameter size class ≤ 10 cm for younger rehabilitated forests, the total above ground biomass/carbon was from this class. These observations suggest that the forests are in the early successional stage. The total above ground biomass obtained for the rehabilitated forest ranged from 4.3 to 4,192.3 kg compared to natural regenerating secondary forest of 3,942.3 kg while total above ground carbon ranged from 1.9 to 1,927.9 kg and 1,820.4 kg, respectively. The mean total above ground biomass accumulated ranged from 1.3 × 10-2 to 20.5 kg/0.04 ha and mean total carbon storage ranged from 5.9 × 10-3 to 9.4 kg/0.04 ha. The total CO2 sequestrated in rehabilitated forest ranged from 6.9 to 7,069.1 kg CO2/0.04 ha. After 19 years, the rehabilitated forest had total above ground biomass and carbon storage comparable to the natural regeneration secondary forest. The forest rehabilitated activities have the potential to increase carbon stock through tree planting. Therefore, forest rehabilitation has shown the potential role as a carbon sink that helps to reduce emissions of greenhouse gases and mitigate climate change

System evaluation for a decision support system

System evaluation is a necessary step in system development process to measure the successfulness of a system. However, this step has often been overlooked by system developers during the development process. This study aimed to discuss several system evaluations for Decision Support Systems (DSSs) and to explain the methodology used to evaluate a DSS model. In this study, a DSS model has been developed to assist decision makers to select an appropriate tree species to be planted for commercial tree planting. Based on few literatures, eight usability factors (efficiency, understandability, operability, attractiveness, error prevention, learnability, accuracy and effectiveness) have been identified for the evaluation process. The results present the usability level for each factor and indicated the tested DSS model is in the excellent level. It is anticipated that system developers can improve the DSS based on these findings as well as from the comments and suggestions made by the respondents

Enhancing the urea-N use efficiency in maize (Zea mays) cultivation on acid soils using urea amended with zeolite and TSP

Problem Statement: Ammonia loss significantly reduces urea-N use efficiency in crop production. Efforts to reduce ammonia loss are laboratory oriented, as such limited in reflecting actual field conditions. This paper reports the effects of urea amended with triple superphosphate (TSP) and zeolite (Clinoptilolite) on soil pH, soil nitrate, soil exchangeable ammonium, dry matter production, N uptake, fresh cob production and urea-N uptake efficiency in maize (Zea mays) cultivation on an acid soil in actual field conditions. Approach: The treatments evaluated were: (i) Normal N, P, K application (74.34 g urea, 27.36 g TSP, 24.12 g KCl) (T1), (ii) Urea-TSP mixture (74.34 g urea+27.36 g TSP)+24.12 g KCl (T2), (iii) 74.34 g urea+27.36 g TSP+9.0 g zeolite (T3), (iv) 74.34 g urea+27.36 g TSP+13.5 g zeolite (T4) and (v) No fertilization (T5). Note, the same amount of 24.12 g KCl was used in T3 and T4 plots. Standard procedures were used to determine the selected chemical properties of zeolite, soil, TSP and urea. The pH of the urea, zeolite, soil and TSP were determined in a 1:2.5 soil: distilled water suspension and/or 0.01 N CaCl2 using a glass electrode. The CEC of the zeolite was determined by the CsCl method. Soil CEC was determined by leaching with 1 N ammonium acetate buffer adjusted to pH 7.0 followed by steam distillation. Soil samples at harvest were analyzed for pH using the method previously outlined. Exchangeable ammonium and nitrate at harvest were extracted from the soil samples by the method of Keeney and Nelson and the amount determined using a LACHAT Autoanalyzer. Total N of the plant tissues (stem and leaf) was determined by the Micro-Kjeldhal method. Results: Urea amended with TSP and zeolite treatments and Urea only (urea without additives) did not have long term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf) production of Swan (test crop). All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved Urea-N uptake efficiency compared to urea without additives or amendment. Conclusion: Urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea

Agroforestry impacts on soil fertility in the Rima'a Valley, Yemen

Yemen is one of the world's least developed countries and experiences problems of scarcity of natural agricultural resources as well as soil erosion and degradation. Agroforestry systems (AFS) are being promoted as a more appropriate land use system than monocropping systems (MCS) worldwide. Unfortunately, long-term studies on agroforestry and other land use systems (LUS) do not exist in Yemen. Agroforestry in the Rima'a region has started to deteriorate and many farmers turned to (MCS). This study was conducted in the Rima'a Valley, near Alsharq town, Dhamar, Yemen. The study evaluates the soil nutrients, organic matter (OM), and other soil properties such as pH, bulk density, and porosity under AFS and compares it with soil under MCS. Standard procedures for soil sampling and analyzing were used to collect and analyze 36 composite samples from Site 1 and 36 composite samples from Site 2 from six cropping systems (treatments). The results showed that there were significant variations in relation to LUS. Agroforestry practices—mixed trees with coffee (S1), and Cordia africana L. with coffee (S2) have higher nitrogen concentration (0.17–0.26%) as compared to the Ziziphus spina-christi L. with maize (S3) and the monocropping maize (S5), (<0.16% in both Sites 1 and 2). Similar results were seen on the effect of the different LUS on the soil P, K, and OM contents at the two sites (p < .01). While soil N, P, and soil K were higher under agroforestry systems S1, and S2 in both sites, it was the lowest in S5 in both sites. It can be concluded that agroforestry has more favorable effects on soil fertility and other soil properties. The government should establish programs and campaigns to disseminate AFS technology and promote the importance of agroforestry in soil conservation

Enhancing the urea-N use efficiency in maize (Zea mays) cultivation on acid soils amended with zeolite and TSP.

Ammonia loss significantly reduces the urea-N use efficiency in crop production. Efforts to reduce this problem are mostly laboratory oriented. This paper reports the effects of urea amended with triple superphosphate (TSP) and zeolite (Clinoptilolite) on soil pH, nitrate, exchangeable ammonium, dry matter production, N uptake, fresh cob production, and urea-N uptake efficiency in maize (Zea mays) cultivation on an acid soil in actual field conditions. Urea-amended TSP and zeolite treatments and urea only (urea without additives) did not have long-term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf) production of Swan (test crop). All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved urea-N uptake efficiency compared to urea without additives or amendment. This suggests that urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea

Using soil water to control ammonia emission from acid soils with and without chicken litter biochar

Although urea use in agriculture is on the increase, increase in pH at soil microsite due to urea hydrolysis which causes ammonia emission can reduce N use efficiency. Among the interventions used to mitigate ammonia loss include urease inhibitors, clinoptilolite zeolite, coated urea, and biochar but with little attention to the use of soil water levels to control ammonia volatilization. The objective of this study was to determine the effects of soil water levels on ammonia volatilization from soils with and without chicken litter biochar. Dry soils with and without chicken litter biochar were subjected to 0%, 25% 50%, 75%, 100%, and 125% soil water. There was no urea hydrolysis in the soil without water. Chicken litter biochar as soil amendment effectively mitigated ammonia loss at 1% to 32% and 80% to 115% field capacity. However, urea used on soil only showed lower ammonia loss at 33% to 79% and 116% to 125% field capacity compared with the soils with chicken litter biochar. At 50% field capacity ammonia loss was high in soils with and without chicken litter biochar. Although chicken litter biochar is reputed for improving soil chemical properties, water levels in this present study affected soil chemical properties differently. Fifty percent field capacity, significantly reduced soil chemical properties. These findings suggest that timely application of urea at the right field capacity can mitigate ammonia emission. Therefore, whether soils are amended with or without chicken litter biochar, urea application should be avoided at 50% field capacity especially in irrigated crops

Mitigating ammonia volatilizatiion from waterlogged acids soils using organic amendments

In production agriculture, granular urea is the most used nitrogen fertilizer in crop production. However, increase in soil pH following application of urea causes ammonia volatilization and reduces N use efficiency. To minimize ammonia loss, organic amendments are used, however, type of organic amendment use could affect urea use efficiency. This study was to determine the effects of organic amendments derived from forest litter, Leucaena leucocephala, chicken litter, and cow dung on ammonia volatilization and chemical properties of a waterlogged acid soil. Treatments evaluated were: (i) T1, Soil only, (ii) T2, Existing recommended fertilization, (iii) T3, Biochar-forest litter compost, (iv) T4, Biochar-chicken litter compost, (v) T5, Biochar-cow dung compost, (vi) T6, Biochar-Leucaena compost, and (vii) T7, Biochar-Leucaena - chicken litter compost. Standard procedures were used to quantify ammonia volatilization and soil chemical properties. The findings of this present study also revealed that the total amount of ammonia loss from urea over a period of forty-two days depends on the influence of the organic amendments on urea hydrolysis. Emissions of ammonia from T6 and T7 were significantly higher because, the decomposition of Leucaena leucocephala favours urea hydrolysis compared with those of T3, T4, and T5. Therefore, Leucaena leucocephala composts should be carefully co-applied with urea to minimize ammonia loss if the aim of using this type of amendments is to improve N use efficiency and soil and crop productivity

Epicuticular wax concentration on Syzygium myrtifolium leaves

The pollution issues are a pervasive and increasing threat to human and forest ecosystem. Plants have been recognised as a method to reduce pollution. However, leaf is the most sensitive organ to pollution where changes in leaf morphological, physiological, anatomical and biochemical can occur. This study was conducted to determine the quantity of epicuticular wax on Syzygium myrtifolium leaves in urban, suburban and industrial areas. Three trees were selected in each of the study sites and new leaves on the branch was marked. 5 g of samples were collected for analysis. Leaf surface particles were extracted by using 20 ml of chloroform in conical flask and was left overnight for hardening where weight were recorded. Data analysis showed that the mean epicuticular wax ranged from 267.2-680.7 µg/m2 with a mean increment of 309.6-950.7 µg/m2 /yr. The epicuticular wax concentration on S. myrtifolium leaves was significantly higher in industrial areas compared to those in the urban and suburban areas. S. myrtifolium at industrial areas are in the open and subjected to direct sunlight and also responding to stress caused by the air pollutions. The low concentration of epicuticular wax was recorded on S. myrtifolium leaves in urban area. These trees are subjected to high concentration of pollutants especially from exhaust emissions and possible is due to the aerosol deposition which have been carried by the wind. This initial study reveal that the level of physiological stress on the trees in industrial, suburban and urban areas are at a different scale where the levels of air pollution is different. Understanding the tree traits are important to capitalize their role as bio filters. This study provide the baseline data for future study where the relationship between the particulate matters deposited on the tree canopy and the tree trait could be explained

Effects of simulated acid rain on Shorea macroptera growth and selected soil chemical properties

There is dearth of information on the effect of acid deposition on Shorea macroptera in Malaysia. Thus, this study was conducted to investigate the potential effect of simulated acid rain (SAR) on S. macroptera growth and selected soil chemical properties. Six treatments were evaluated in this study. Growth variables of S. macroptera were observed for 90 days. After 90 days, seedlings and soil were sampled and analyzed using standard methods. The seedlings height decreased with decrease in SAR pH. Chlorosis and necrosis were observed for low SAR pH (pH 3.5 and 4) treatments and this observation explains the reduction of dry matter production of the plants subjected to these treatments. Regardless of treatment, K, Ca, Mg and Na contents in the plants and soil were statistically similar. A similar observation was found for soil exchangeable Fe, Cu, Zn, acidity, Al and H. Thus, it can be concluded that SAR pH of 3.5, 4 and 4.5 affects S. macroptera height, biomass and selected nutrient contents in soil. S. macroptera is susceptible to acid deposition and it could be considered as one of the bio-indicators in Malaysia. A field study is recommended to validate the findings of this study