CONTRIBUTION OF THE HEART OF BORNEO (HoB) INITIATIVE TOWARDS BOTANICAL EXPLORATION IN SABAH, MALAYSIA

The Heart of   Borneo (HoB) declaration is a conservation agreement initiated by WWF and signed by three countries, i.e., Brunei       Darussalam, Indonesia and Malaysia in Bali, Indonesia on 12th February 2007 to protect more than 23 million hectares of forested region on Borneo Island. These forested areas could be well protected when conservation management plan is in place. One of the crucial activities to facilitate the planning and formulation of conservation plan is to conduct  scientific expeditions that include botanical exploration. The primary objective of the expedition is to identify the key conservation targets within the forest reserves. For the past five years, several expeditions have been conducted by the Sabah Forestry Department under the auspices of the HoB project to explore various forest reserves with conservation issues within the Heart of Borneo area. This paper will present the findings which include plant richness, endemism and plant conservation status in each forest reserves that has been explored. </p

Liana habitat associations and community structure in a Bornean lowland tropical forest

Lianas (woody vines) contribute substantially to the diversity and structure of most tropical forests, yet little is known about the importance of habitat specialization in maintaining tropical liana diversity and the causes of variation among forests in liana abundance and species composition. We examined habitat associations, species diversity, species composition, and community structure of lianas at Sepilok Forest Reserve, Sabah, Malaysia in northeastern Borneo among three soil types that give rise to three distinct forest types of lowland tropical rain forest: alluvial, sandstone hill, and kerangas (heath) forest. Alluvial soils are more nutrient rich and have higher soil moisture than sandstone soils, whereas kerangas soils are the most nutrient poor and drought prone. Lianas ≥0.5-cm in diameter were measured, tagged, and identified to species in three square 0.25-ha plots in each forest type. The number of lianas ≥0.5 cm did not differ significantly among forest types and averaged 1348 lianas ha-1, but mean liana stem diameter, basal area, estimated biomass, species richness, and Fisher\u27s α diversity index were all greater for plots in alluvial than sandstone or kerangas forests. Liana species composition also differed greatly among the three habitats, with 71% of species showing significant positive or negative habitat associations. Sandstone forests were intermediate to alluvial and kerangas forests in most aspects of liana community structure and composition, and fewer species showed significant habitat associations with this forest type. Ranking of forest types with respect to liana density, biomass, and diversity matches the ranking in soil fertility and water availability (alluvial \u3e sandstone hill \u3e kerangas). These results suggest that edaphic factors play an important role in maintaining liana species diversity and structuring liana communities. © Springer 2006

Checklist of trees in Crocker Range Park permanent research plot, Sabah, Malaysia

This paper presents a checklist of trees from six 0.25 ha permanent research plots in Crocker Range Park (CRP). A total of 73 tree families with 199 genera and 527 species were identified from the plots. Euphorbiaceae was the largest family, with 15 genera containing 52 species. The other dominant tree families in terms of species composition were Myrtaceae, Lauraceae, Meliaceae, Rubiaceae, Moraceae and Annonaceae. The timber tree family, Dipterocarpaceae, consisted of 19 species with Shorea being the species rich genus. There were 21 least dominant families that were respresented by only one species. At least 47 species are new records for CRP, while three species are new records for Sabah - Gonystylus nervosus, Sterculia rhynchophylla and Palaquium ferrugineum. Seventy tree species were found to be endemic to Borneo, and seven species could be Sabah endemics. The findings of this paper show that CRP is diverse is diverse and rich in terms of tree flora

A trait-based trade-off between growth and mortality: Evidence from 15 tropical tree species using size-specific relative growth rates

A life-history trade-offbetween low mortality in the dark and rapid growth in the light is one of the most widely accepted mechanisms underlying plant ecological strategies in tropical forests. Differences in plant functional traits are thought to underlie these distinct ecological strategies; however, very few studies have shown relationships between functional traits and demographic rates within a functional group. We present 8 years of growth and mortality data from saplings of 15 species of Dipterocarpaceae planted into logged-over forest in Malaysian Borneo, and the relationships between these demographic rates and four key functional traits: wood density, specific leaf area (SLA), seed mass, and leaf C:N ratio. Species-specific differences in growth rates were separated from seedling size effects by fitting nonlinear mixed-effects models, to repeated measurements taken on individuals at multiple time points. Mortality data were analyzed using binary logistic regressions in a mixed-effects models framework. Growth increased and mortality decreased with increasing light availability. Species differed in both their growth and mortality rates, yet there was little evidence for a statistical interaction between species and light for either response. There was a positive relationship between growth rate and the predicted probability of mortality regardless of light environment, suggesting that this relationship may be driven by a general trade-offbetween traits that maximize growth and traits that minimize mortality, rather than through differential species responses to light. Our results indicate that wood density is an important trait that indicates both the ability of species to grow and resistance to mortality, but no other trait was correlated with either growth or mortality. Therefore, the growth mortality trade-offamong species of dipterocarp appears to be general in being independent of species crossovers in performance in different light environments. &copy; 2014 The Authors

Remote sensing liana infestation in an aseasonal tropical forest:addressing mismatch in spatial units of analyses

The ability to accurately assess liana (woody vine) infestation at the landscape level is essential to quantify their impact on carbon dynamics and help inform targeted forest management and conservation action. Remote sensing techniques provide potential solutions for assessing liana infestation at broader spatial scales. However, their use so far has been limited to seasonal forests, where there is a high spectral contrast between lianas and trees. Additionally, the ability to align the spatial units of remotely sensed data with canopy observations of liana infestation requires further attention. We combined airborne hyperspectral and LiDAR data with a neural network machine learning classification to assess the distribution of liana infestation at the landscape‐level across an aseasonal primary forest in Sabah, Malaysia. We tested whether an object‐based classification was more effective at predicting liana infestation when compared to a pixel‐based classification. We found a stronger relationship between predicted and observed liana infestation when using a pixel‐based approach (RMSD = 27.0% ± 0.80) in comparison to an object‐based approach (RMSD = 32.6% ± 4.84). However, there was no significant difference in accuracy for object‐ versus pixel‐based classifications when liana infestation was grouped into three classes; Low [0–30%], Medium [31–69%] and High [70–100%] (McNemar’s χ2 = 0.211, P = 0.65). We demonstrate, for the first time, that remote sensing approaches are effective in accurately assessing liana infestation at a landscape scale in an aseasonal tropical forest. Our results indicate potential limitations in object‐based approaches which require refinement in order to accurately segment imagery across contiguous closed‐canopy forests. We conclude that the decision on whether to use a pixel‐ or object‐based approach may depend on the structure of the forest and the ultimate application of the resulting output. Both approaches will provide a valuable tool to inform effective conservation and forest management

Drought cuts back regeneration in logged tropical forests

Logged tropical forests represent a major opportunity for preserving biodiversity and sequestering carbon, playing a large role in meeting global forest restoration targets. Left alone, these ecosystems have been expected to undergo natural regeneration and succession towards old growth forests, but extreme drought events may challenge this process. While old growth forests possess a certain level of resilience, we lack understanding as to how logging may affect forest responses to drought. This study examines the drought–logging interaction in seedling dynamics within a landscape of logged and unlogged forests in Sabah Malaysia, based on 73 plots monitored before and after the 2015-16 El Niño drought. Drought increased seedling mortality in all forests, but the magnitude of this impact was modulated by logging intensity, with forests with lower canopy leaf area index (LAI) and above ground biomass (AGB) experiencing greater drought induced mortality. Moreover, community traits in more heavily logged forests shifted towards being more ruderal after drought, suggesting that the trajectory of forest succession had been reversed. These results indicate that with reoccurring strong droughts under a changing climate, logged forests that have had over half of their biomass removed may suffer permanently arrested succession. Targeted management interventions may therefore be necessary to lift the vulnerable forests above the biomass threshold

Three decades of post-logging tree community recovery in naturally regenerating and actively restored dipterocarp forest in Borneo

Selective logging has affected large areas of tropical forests and there is increasing interest in how to manage selectively logged forests to enhance recovery. However, the impacts of logging and active restoration, by liberation cutting and enrichment planting, on tree community composition are poorly understood compared to trajectories of biomass recovery. Here, we assess the long-term impacts of selective logging and active restoration for biomass recovery on tree species diversity, community composition, and forest structure. We censused all stems ≥2 cm diameter at breast height (DBH) on 46 permanent plots in unlogged, primary forest in the Danum Valley Conservation Area (DVCA; 12 plots, totalling 0.6 ha) and in sites logged 23–35 years prior to the census in the Ulu Segama Forest Reserve adjacent to DVCA (34 plots, totalling 1.7 ha) in Sabah, Malaysian Borneo. Active restoration treatments, including enrichment planting and climber cutting, were implemented on 17 of the logged forest plots 12–24 years prior to the census. Total plot-level basal area and pole (5–10 cm DBH) stem density were lower in logged than unlogged forests, however no difference was found in stem density amongst saplings (2–5 cm DBH) or established trees (≥10 cm DBH). Neither basal area, nor plot-level stem density varied with time since logging at any size class, although sapling and pole stem densities were lower in actively restored than naturally regenerating logged forest. Sapling species diversity was lower in logged than unlogged forest, however there were no other significant effects of logging on tree species richness or diversity indices. Tree species composition, however, differed between logged and unlogged forests across all stem size classes (PERMANOVA), reflected by 23 significant indicator species that were only present in unlogged forest. PERMANOVA tests revealed no evidence that overall species composition changed with time since logging or with active restoration treatments at any size class. However, when naturally regenerating and actively restored communities were compared, two indicator species were identified in naturally regenerating forest and three in actively restored forests. Together our results suggest that selective logging has a lasting effect on tree community composition regardless of active restoration treatments and, even when species richness and diversity are stable, species composition remains distinct from unlogged forest for more than two decades post-harvest. Active restoration efforts should be targeted, monitored, and refined to try to ensure positive outcomes for multiple metrics of forest recovery

Bornean tropical forests recovering from logging at risk of regeneration failure

AUTHOR CONTRIBUTIONS David C. Bartholomew: Conceptualization; formal analysis; investigation; methodology; project administration; visualization; writing – original draft; writing – review and editing. Robin Hayward: Formal analysis; methodology; visualization; writing – original draft; writing – review and editing. David F. R. P. Burslem: Conceptualization; funding acquisition; methodology; supervision; writing – review and editing. Paulo R. L. Bittencourt: Conceptualization; investigation; methodology; writing – review and editing. Daniel Chapman: Formal analysis; writing – review and editing. Mohd. Aminur Faiz Bin Suis: Project administration. Reuben Nilus: Project administration. Michael J. O'Brien: Conceptualization; investigation; methodology; project administration; writing – review and editing. Glen Reynolds: Project administration. Lucy Rowland: Conceptualization; funding acquisition; methodology; supervision; writing – review and editing. Lindsay F. Banin: Conceptualization; funding acquisition; methodology; supervision; writing – review and editing. Daisy Dent: Conceptualization; funding acquisition; methodology; supervision; writing – review and editing.Peer reviewe

Synergistic use of Landsat 8 OLI image and airborne LiDAR data for aboveground biomass estimation in tropical lowland rainforests

Developing a robust and cost-effective method for accurately estimating tropical forest’s carbon pool over large area is a fundamental requirement for the implementation of Reducing Emissions from Deforestation and forest Degradation (REDD+). This study aims at examining the independent and combined use of airborne LiDAR and Landsat 8 Operational Land Imager (OLI) data to accurately estimate the above-ground biomass (AGB) of primary tropical rainforests in Sabah, Malaysia. Thirty field plots were established in three types of lowland rainforests: alluvial, sandstone hill and heath forests that represent a wide range of AGB density and stand structure. We derived the height percentile and laser penetration variables from the airborne LiDAR and calculated the vegetation indices, tasseled cap transformation values, and the texture measures from Landsat 8 OLI data. We found that there are moderate correlations between the AGB and laser penetration variables from airborne LiDAR data (r = −0.411 to −0.790). For Landsat 8 OLI data, the 6 vegetation indices and the 46 texture measures also significantly correlated with the AGB (r = 0.366–0.519). Stepwise multiple regression analysis was performed to establish the estimation models for independent and combined use of airborne LiDAR and Landsat 8 OLI data. The results showed that the model based on a combination of the two remote sensing data achieved the highest accuracy (R2 adj = 0.81, RMSE = 17.36%) whereas the models using Landsat 8 OLI data airborne LiDAR data independently obtained the moderate accuracy (R2 adj = 0.52, RMSE = 24.22% and R2 adj = 0.63, RMSE = 25.25%, respectively). Our study indicated that texture measures from Landsat 8 OLI data provided useful information for AGB estimation and synergistic use of Landsat 8 OLI and airborne LiDAR data could improve the AGB estimation of primary tropical rainforest

Differential nutrient limitation and tree height control leaf physiology, supporting niche partitioning in tropical dipterocarp forests

1. Revealing the mechanisms of environmental niche partitioning within lowland tropical forests is important for understanding the drivers of current species distributions and potential vulnerability to environmental change. Tropical forest structure and species composition change across edaphic gradients in Borneo over short distances. However, our understanding of how edaphic conditions affect tree physiology and whether these relationships drive niche partitioning within Bornean forests remains incomplete. 2. This study evaluated how leaf physiological function changes with nutrient availability across a fine-scale edaphic gradient and whether these relationships vary according to tree height. Furthermore, we tested whether intraspecific leaf trait variation allows generalist species to populate a wider range of environments. 3. We measured leaf traits of 218 trees ranging in height from 4 to 66 m from 13 dipterocarp species within four tropical forest types (alluvial, mudstone, sandstone and kerangas) occurring along an <5 km edaphic gradient in North Borneo. The traits measured included saturating photosynthesis (Asat), maximum photosynthetic capacity (Vcmax), leaf dark respiration (Rleaf), leaf mass per area (LMA), leaf thickness, minimum stomatal conductance (gdark) and leaf nutrient concentrations (N, P, Ca, K and Mg). 4. Across all species, leaf traits varied consistently in response to soil nutrient availability across forest types except Rleaf_mass, [Mg]leaf and [Ca]leaf. Changes in photosynthesis and respiration rates were related to different leaf nutrients across forest types, with greater nutrient-use efficiency in more nutrient-poor environments. Generalist species partially or fully compensated reductions in mass-based photosynthesis through increasing LMA in more nutrient-poor environments. 5. Leaf traits also varied with tree height, except Vcmax_mass, but only in response to height-related modifications of leaf morphology (LMA and leaf thickness). These height–trait relationships did not vary across the edaphic gradient, except for Asat, [N]leaf, [P]leaf and [K]leaf. 6. Our results highlight that modification of leaf physiological function and morphology act as important adaptations for Bornean dipterocarps in response to edaphic and vertical environmental gradients. Meanwhile, multiple nutrients appear to contribute to niche partitioning and could drive species distributions and high biodiversity within Bornean forest landscapes