The equatorial peatlands of the Kutai lowland of eastern Kalimantan are generally 4–10 m in thickness but some sections exceed 16 m in depth. The deposition of peat commenced about 8000 yrs ago after shallow flooding of the basin by the Mahakam River. The earliest vegetation is aPandanusswamp which grades upwards to swamp forest dominated by dipterocarps. The peatland has expanded laterally and rivers have maintained narrow levee-channel tracks through the swamp, which has grown vertically in balance with river accretion. Historical fires are associated with extreme El Niño years of drought, but human agency is important. The fires of 1982–1983 and 1997–1998 burnt up to 85% of the vegetation on the peatland. Although charcoal analyses show that fire has occurred throughout the history of the peatland, it is rare in forests remote from rivers until the last 3000 years and only common within the last millennium. Fires are earlier and more frequent in sites accessible from waterways, and floodplains have been widely burnt down to water table or below, forming extensive lakes.

It is unclear to what extent emissions of nitrous oxide (N₂O) from drained histosols in the tropics may contribute to the atmospheric burden of greenhouse gases. In particular, there is a critical need to elucidate their magnitude in oil palm plantations on these soils. We examined spatio-temporal variations of N₂O emissions from peat decomposition and nitrogen (N) fertilization in a plantation trial in Sumatra, which included three application rates: 0 (N0), 153 (N1) and 306 (N2) kg N ha⁻¹ y⁻¹. The spatially stratified sampling design distinguished the area around the palms which received fertilizer (9% of the surface) from the rest of the plot which was unfertilized. Annual emissions were substantial with rates of 22.1 ± 5.7, 12.8 ± 2.7 and 26.6 ± 5.7 kg N₂O-N ha⁻¹ in the N0, N1 and N2 treatments, respectively. These equal 9.3 ± 2.4, 5.4 ± 1.1 and 11.2 ± 2.4 Mg CO₂eq ha⁻¹ y⁻¹, or 5–10 times emission rates in natural peatland forest. The site exhibited two persistent hotspots located in the unfertilized zone, contributing 33 and 46% of annual emissions in N0 and N2 while representing only 10% of the area sampled. The response of emissions to fertilization was exponential but restricted to the small N application area. At the plot scale and over the year, the impact of fertilized-induced emissions was minimal due to the prevalence of emissions from peat decomposition. Annual rates among treatments were similar when discarding the contribution of hotspots to evaluate N addition effect. High N₂O emissions from peat decomposition in the tropics tend to be common within the restricted existing literature; which is in contrast with most recent IPCC emission factors. Our results emphasize the importance to integrate N₂O emissions in greenhouse gas budgets of plantations on peat, despite the predominance of CO₂ in total emissions.

ANALISIS KEBERLANJUTAN USAHATANI PADI SAWAH DI KECAMATAN SOREANG KABUPATEN BANDUNG

In the current decade, effective management of electronic waste (e-waste) has emerged as a critical research area. Therefore, this research aimed to identify the current trend, future directions, and key enabler factors for e-waste management by conducting bibliometric analysis and literature review. Using the Scopus database, 441 peer-reviewed papers from 2012 to 2021 were collected for bibliometric analysis. To visualize the data, research mapping tools such as Biblioshiny and VOSviewer were employed. In addition to the bibliometric analysis, a literature review was conducted on the top ten articles to identify enabler factors influencing e-waste management. The analysis showed keywords such as “e-waste”, “recycling”, “e-waste management”, “sustainability”, “e-waste”, and “circular economy”. Additionally, some key motor themes of e-waste management field were identified, including “policy”, “human health”, “developing countries”, “e-waste management”, and “strategies” through thematic analysis. This research suggests that there are five dimensions of enablers in e-waste management: policy, economy, social, environmental, and technology. The combination of VOSviewer and Biblioshiny tools for bibliometric analysis along with a literature review proved to be a powerful and beneficial approach for scientific mapping and identifying the driving factors of e-waste management.