An Investigation of Soil Physico-Chemical Variables Across Different Lowland Forest Ecosystems of Brunei Darussalam

Abstract

Tropical forests undisputedly harbor the largest share of global plant diversity, but the mechanisms of maintenance for this diversity cannot be well understood without good data on environmental variables, primarily soil characteristics. This study investigates differences in soil physico-chemical properties in various tropical lowland forest types in Brunei Darussalam, in the Northwest Borneo plant diversity hotspot. Nine different vegetation types were investigated: intact primary mixed-dipterocarp forest, old disturbed secondary forest, young disturbed secondary forest (partly invaded by alien Acacias), heath (Kerangas) forest, peat swamp forest, swampy heath (Kerapah) forest, core mangrove, fringe mangrove and island mangrove forests. Nine 60 x 20 m plots were set up, and sampled for soils at topsoil (0-15 cm depth) and subsoil (15-30 cm depth) layers. Soil gravimetric water and organic matter content, texture, nutrient concentrations, pH, and salinity were determined. The peat swamp and core mangrove forests recorded highest soil nutrient concentrations. Peat swamp forest had the highest GWC, OM content, total N, and total Ca recorded, whereas the soil in core mangrove forest had higher total P, total Mg, total K, exchangeable Mg, exchangeable Ca, exchangeable K and salinity compared to the other habitat types. These results were also highlighted by the principal component analysis for the soil parameters measured. The most nutrient-poor soils were found in the Kerapah and heath forest sites. The difference between topsoil and subsoil for soil variables were generally not significantly different from each other. The present study has shown that soil physico-chemical properties differ significantly between the nine vegetation types studied, and this may have important implications upon differences seen in plant community compositions in these vegetation types.

Tree Diversity and Community Composition of the Tutong White Sands, Brunei Darussalam: A Rare Tropical Heath Forest Ecosystem

“…The range of GWC values in the six plots was comparable to values recorded from Kerangas forests in Bukit Sawat and Sungai Mau, Brunei Darussalam [38,39], as well as those observed from Kerangas forests in Brunei and Sarawak [18,40]. The range of pH values we recorded (3.85-4.7) is consistent with 6 International Journal of Ecology those from other Bornean heath forests [19,31,40,41] and Amazonia caatinga [42,43].…”

Soil niche of rain forest plant lineages: Implications for dominance on a global scale

“…10 years, partly co‐dominated by invasive Australian Acacia trees), (d) peat swamp forest, (e) heath forest (kerangas), (f) kerapah forest, intermediate between the former two, (g) matrix mangrove forest, (h) fringe mangrove forest, and (i) island mangroves (see Jaafar et al () for details on the localities).These main forest types in the region (i.e. lowland dipterocarp forest, peat swamp forest, kerangas and mangroves) differ vastly in terms of their soil physico‐chemical characteristics and plant assemblages (Jaafar et al, ; Slik et al, ), while intermediate and disturbed forest types were included to cover a broader spectrum of values for soil variables. Different mangrove forest subtypes have different levels of exposure to seawater, creating microhabitats suitable for diverse animal and plant assemblages (Procheş, Marshall, Ugrasen, & Ramcharan, ; Satyanarayana et al, ).…”

“…In comparison, the Central African and Neotropical rain forests are more isolated (Procheş & Ramdhani, 2013). This means that the array (h) fringe mangrove forest, and (i) island mangroves (see Jaafar et al (2016) for details on the localities).These main forest types in the region (i.e. lowland dipterocarp forest, peat swamp forest, kerangas and mangroves) differ vastly in terms of their soil physico-chemical characteristics and plant assemblages (Jaafar et al, 2016;Slik et al, 2009), while intermediate and disturbed forest types were included to cover a broader spectrum of values for soil variables.…”

“…To achieve this, we initially address two descriptive objectives. In order to identify equal‐aged plant lineages that have high levels of occupancy and dominance across soil types within one region, we describe patterns of lineage distribution and pervasiveness across nine Bornean forest types that comprise highly contrasting soil physico‐chemical features (Jaafar, Sukri, & Procheş, ). Soil niche characteristics of multiple ancient plant lineages have not, to our knowledge, been previously explored. To this end, we study the influence of soil properties characteristics on the occurrence of species, families and lineages.…”

“…1. In order to identify equal-aged plant lineages that have high levels of occupancy and dominance across soil types within one region, we describe patterns of lineage distribution and pervasiveness across nine Bornean forest types that comprise highly contrasting soil physico-chemical features (Jaafar, Sukri, & Procheş, 2016).…”