Displaying publications 1 - 20 of 189 in total

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  1. Fulltext Major cellular events in peripheral nerve regeneration: A brief overview
    Naidu, M., David, P.
    International Medical Journal Malaysia, 2009;8(1):61-64.
    MyJurnal
    Injury to a peripheral nerve leads to degeneration of the segment distal to the site of lesion, a process referred to as Wallerian degeneration. During Wallerian degeneration, axons and myelin sheaths undergo degeneration and are phagocytosed by macrophages and Schwann cells. The Schwann cells proliferate and the endoneurial tubes persist, together the whole structure is known as the band of Büngner. Within few hours, the damaged axons in the proximal stump initiate a regeneration response, with formation of new growth cones. During Wallerian degeneration, neurotrophins, neural cell adhesion molecules, cytokines and other soluble factors are upregulated to facilitate regeneration. The recovery of the target in mammals is often variable, but almost never complete. In humans, scar tissue forms at the site of lesion and this often results in poor recovery of the target. The major events underlying this regenerative process is highlighted and discussed in this review.
  2. Fulltext The effects of restoring logged tropical forests on avian phylogenetic and functional diversity
    Cosset CCP, Edwards DP
    Ecol Appl, 2017 09;27(6):1932-1945.
    PMID: 28543995 DOI: 10.1002/eap.1578
    Selective logging is the most prevalent land-use change in the tropics. Despite the resulting degradation of forest structure, selectively logged forests still harbor a substantial amount of biodiversity leading to suggestions that their protection is the next best alternative to conserving primary, old-growth forests. Restoring carbon stocks under Reducing Emissions from Deforestation and Forest Degradation (REDD+) schemes is a potential method for obtaining funding to protect logged forests, via enrichment planting and liberation cutting of vines. This study investigates the impacts of restoring logged forests in Borneo on avian phylogenetic diversity, the total evolutionary history shared across all species within a community, and on functional diversity, with important implications for the protection of evolutionarily unique species and the provision of many ecosystem services. Overall and understorey avifaunal communities were studied using point count and mist netting surveys, respectively. Restoration caused a significant loss in phylogenetic diversity and MPD (mean pairwise distance) leaving an overall bird community of less total evolutionary history and more closely related species compared to unlogged forests, while the understorey bird community had MNTD (mean nearest taxon distance) that returned toward the lower levels found in a primary forest, indicating more closely related species pairs. The overall bird community experienced a significant loss of functional strategies and species with more specialized traits in restored forests compared to that of unlogged forests, which led to functional clustering in the community. Restoration also led to a reduction in functional richness and thus niches occupied in the understorey bird community compared to unlogged forests. While there are additional benefits of restoration for forest regeneration, carbon sequestration, future timber harvests, and potentially reduced threat of forest conversion, this must be weighed against the apparent loss of phylogenetic and functional diversity from unlogged forest levels, making the biodiversity-friendliness of carbon sequestration schemes questionable under future REDD+ agreements. To reduce perverse biodiversity outcomes, it is important to focus restoration only on the most degraded areas or at reduced intensity where breaks between regimes are incorporated.
  3. A contemporary decennial examination of changing agricultural field sizes using Landsat time series data
    White EV, Roy DP
    Geo, 2015 04 07;2(1):33-54.
    PMID: 27669424
    Field size distributions and their changes have not been studied over large areas as field size change datasets are not available. This study quantifies agricultural field size changes in a consistent manner using Landsat satellite data that also provide geographic context for the observed decadal scale changes. Growing season cloud-free Landsat 30 m resolution images acquired from 9 to 25 years apart were used to extract field object classifications at seven sites located by examination of a global agricultural yield map, agricultural production statistics, literature review, and analysis of the imagery in the US Landsat archive. High spatial resolution data were used to illustrate issues identifying small fields that are not reliably discernible at 30 m Landsat resolution. The predominant driver of field size change was attributed by literature review. Significant field size changes were driven by different factors, including technological advancements (Argentina and USA), government land use and agricultural policies (Malaysia, Brazil, France), and political changes (Albania and Zimbabwe). While observed local field size changes were complex, the reported results suggest that median field sizes are increasing due to technological advancements and changes to government policy, but may decrease where abrupt political changes affect the agricultural sector and where pastures are converted to arable land uses. In the limited sample considered, median field sizes increased from 45% (France) to 159% (Argentina) and decreased from 47% (Brazil) to 86% (Albania). These changes imply significant impacts on landscape spatial configuration and land use diversity with ecological and biogeochemical consequences.
  4. Fulltext Analysis of web-based travel health advice provided to international travellers with chronic medical and psychiatric illnesses
    Rofaiel DP, Hession P, Flaherty GT
    Int J Med Inform, 2021 Oct;154:104566.
    PMID: 34520934 DOI: 10.1016/j.ijmedinf.2021.104566
    OBJECTIVES: The internet is an important source of travel health information. Individuals living with chronic illnesses consult patient organisation websites for illness-related information. We analysed the scope of online travel health information available to patients with pre-existing medical conditions.

    STUDY DESIGN: A descriptive content analysis of patient organisation websites was conducted.

    METHODS: The Google® search engine was interrogated using search terms related to the principal chronic diseases from the Global Burden of Disease Study. Data relating to 41 travel health variables were extracted from each eligible website. An aggregate quality score was derived for each organisation based on the presence of specific website information. Visitor usage and search analytics for each organisation's website were also described.

    RESULTS: We examined 145 official organisation websites relating to 10 major chronic illnesses. The largest number of websites was retrieved for patients with cancer (n = 36). Only 21 (16.5%) websites provided information on fitness-to-travel considerations. COPD websites had the highest average quality score (17.68%), followed by diabetes (14.91%) and dementia (13.28%). Mental health illness websites had the lowest score of 1.33%. There was a trend towards increased emphasis on pre-travel preparation and medications. Insect bite avoidance, malaria, animal bites, jet lag, and repatriation were addressed to the least extent.

    CONCLUSIONS: Our analysis exposes significant deficits in the coverage of travel health topics. Patient organisations should provide accessible pre-travel health advice to website users. Future research should elucidate the influence of web-based pre-travel health information on the behaviour of travellers with chronic disease.

  5. The effects of prenatal alcohol exposure on the morphological characteristics of spinal motoneurons
    David P, Subramaniam K
    Birth Defects Res. Part A Clin. Mol. Teratol., 2009 Sep;85(9):791-9.
    PMID: 19452514 DOI: 10.1002/bdra.20593
    Clinical studies and research in animals have established that alcohol consumption during pregnancy produces irreversible developmental anomalies. Deficits in fine motor performance are often noted in infants diagnosed with fetal alcohol syndrome. However, the effects of alcohol on the spinal motoneurons have not been examined. In this study, the morphometric alterations in spinal motoneurons were assessed as a result of prenatal alcohol exposure.
  6. Prenatal alcohol exposure and early postnatal changes in the developing nerve-muscle system
    David P, Subramaniam K
    Birth Defects Res. Part A Clin. Mol. Teratol., 2005 Nov;73(11):897-903.
    PMID: 16228975
    Extensive research on prenatal alcohol exposure has proven the potent teratogenicity of this substance of abuse. Children born to alcoholic mothers are often diagnosed with fetal alcohol syndrome (FAS). Those afflicted with FAS often have muscle weakness, muscle wasting, and atrophy. This study assessed the effects of prenatal alcohol exposure on the developing rat neuromuscular system.
  7. Fulltext Sustainable management in crop monocultures: the impact of retaining forest on oil palm yield
    Edwards FA, Edwards DP, Sloan S, Hamer KC
    PLoS One, 2014;9(3):e91695.
    PMID: 24638038 DOI: 10.1371/journal.pone.0091695
    Tropical agriculture is expanding rapidly at the expense of forest, driving a global extinction crisis. How to create agricultural landscapes that minimise the clearance of forest and maximise sustainability is thus a key issue. One possibility is protecting natural forest within or adjacent to crop monocultures to harness important ecosystem services provided by biodiversity spill-over that may facilitate production. Yet this contrasts with the conflicting potential that the retention of forest exports dis-services, such as agricultural pests. We focus on oil palm and obtained yields from 499 plantation parcels spanning a total of ≈23,000 ha of oil palm plantation in Sabah, Malaysian Borneo. We investigate the relationship between the extent and proximity of both contiguous and fragmented dipterocarp forest cover and oil palm yield, controlling for variation in oil palm age and for environmental heterogeneity by incorporating proximity to non-native forestry plantations, other oil palm plantations, and large rivers, elevation and soil type in our models. The extent of forest cover and proximity to dipterocarp forest were not significant predictors of oil palm yield. Similarly, proximity to large rivers and other oil palm plantations, as well as soil type had no significant effect. Instead, lower elevation and closer proximity to forestry plantations had significant positive impacts on oil palm yield. These findings suggest that if dipterocarp forests are exporting ecosystem service benefits or ecosystem dis-services, that the net effect on yield is neutral. There is thus no evidence to support arguments that forest should be retained within or adjacent to oil palm monocultures for the provision of ecosystem services that benefit yield. We urge for more nuanced assessments of the impacts of forest and biodiversity on yields in crop monocultures to better understand their role in sustainable agriculture.
  8. Fulltext Tropical forests are thermally buffered despite intensive selective logging
    Senior RA, Hill JK, Benedick S, Edwards DP
    Glob Chang Biol, 2018 03;24(3):1267-1278.
    PMID: 29052295 DOI: 10.1111/gcb.13914
    Tropical rainforests are subject to extensive degradation by commercial selective logging. Despite pervasive changes to forest structure, selectively logged forests represent vital refugia for global biodiversity. The ability of these forests to buffer temperature-sensitive species from climate warming will be an important determinant of their future conservation value, although this topic remains largely unexplored. Thermal buffering potential is broadly determined by: (i) the difference between the "macroclimate" (climate at a local scale, m to ha) and the "microclimate" (climate at a fine-scale, mm to m, that is distinct from the macroclimate); (ii) thermal stability of microclimates (e.g. variation in daily temperatures); and (iii) the availability of microclimates to organisms. We compared these metrics in undisturbed primary forest and intensively logged forest on Borneo, using thermal images to capture cool microclimates on the surface of the forest floor, and information from dataloggers placed inside deadwood, tree holes and leaf litter. Although major differences in forest structure remained 9-12 years after repeated selective logging, we found that logging activity had very little effect on thermal buffering, in terms of macroclimate and microclimate temperatures, and the overall availability of microclimates. For 1°C warming in the macroclimate, temperature inside deadwood, tree holes and leaf litter warmed slightly more in primary forest than in logged forest, but the effect amounted to <0.1°C difference between forest types. We therefore conclude that selectively logged forests are similar to primary forests in their potential for thermal buffering, and subsequent ability to retain temperature-sensitive species under climate change. Selectively logged forests can play a crucial role in the long-term maintenance of global biodiversity.
  9. Fulltext Impact of logging and forest conversion to oil palm plantations on soil bacterial communities in Borneo
    Lee-Cruz L, Edwards DP, Tripathi BM, Adams JM
    Appl Environ Microbiol, 2013 Dec;79(23):7290-7.
    PMID: 24056463 DOI: 10.1128/AEM.02541-13
    Tropical forests are being rapidly altered by logging and cleared for agriculture. Understanding the effects of these land use changes on soil bacteria, which constitute a large proportion of total biodiversity and perform important ecosystem functions, is a major conservation frontier. Here we studied the effects of logging history and forest conversion to oil palm plantations in Sabah, Borneo, on the soil bacterial community. We used paired-end Illumina sequencing of the 16S rRNA gene, V3 region, to compare the bacterial communities in primary, once-logged, and twice-logged forest and land converted to oil palm plantations. Bacteria were grouped into operational taxonomic units (OTUs) at the 97% similarity level, and OTU richness and local-scale α-diversity showed no difference between the various forest types and oil palm plantations. Focusing on the turnover of bacteria across space, true β-diversity was higher in oil palm plantation soil than in forest soil, whereas community dissimilarity-based metrics of β-diversity were only marginally different between habitats, suggesting that at large scales, oil palm plantation soil could have higher overall γ-diversity than forest soil, driven by a slightly more heterogeneous community across space. Clearance of primary and logged forest for oil palm plantations did, however, significantly impact the composition of soil bacterial communities, reflecting in part the loss of some forest bacteria, whereas primary and logged forests did not differ in composition. Overall, our results suggest that the soil bacteria of tropical forest are to some extent resilient or resistant to logging but that the impacts of forest conversion to oil palm plantations are more severe.
  10. Fulltext Tropical land-use change alters trait-based community assembly rules for dung beetles and birds
    Edwards FA, Edwards DP, Hamer KC, Fayle TM
    Oecologia, 2021 Mar;195(3):705-717.
    PMID: 33559003 DOI: 10.1007/s00442-020-04829-z
    Tropical rainforest disturbance and conversion are critical drivers of biodiversity loss. A key knowledge gap is understanding the impacts of habitat modification on mechanisms of community assembly, which are predicted to respond differently between taxa and across spatial scales. We use a null model approach to detect trait assembly of species at local- and landscape-scales, and then subdivide communities with different habitat associations and foraging guilds to investigate whether the detection of assembly mechanisms varies between groups. We focus on two indicator taxa, dung beetles and birds, across a disturbance gradient of primary rainforest, selectively logged rainforest, and oil palm plantations in Borneo, Southeast Asia. Random community assembly was predominant for dung beetles across habitats, whereas trait convergence, indicative of environmental filtering, occurred across the disturbance gradient for birds. Assembly patterns at the two spatial scales were similar. Subdividing for habitat association and foraging guild revealed patterns hidden when focusing on the overall community. Dung beetle forest specialists and habitat generalists showed opposing assembly mechanisms in primary forest, community assembly of habitat generalists for both taxa differed with disturbance intensity, and insectivorous birds strongly influenced overall community assembly relative to other guilds. Our study reveals the sensitivity of community assembly mechanisms to anthropogenic disturbance via a shift in the relative contribution of stochastic and deterministic processes. This highlights the need for greater understanding of how habitat modification alters species interactions and the importance of incorporating species' traits within assessments.
  11. On some taxonomically confused species of the genus Amphiesma Duméril, Bibron & Duméril, 1854 related to Amphiesma khasiense (Boulenger, 1890) (Squamata, Natricidae)
    David P, Vogel G, Van Rooijen J
    Zootaxa, 2013;3694:301-35.
    PMID: 26312293
    Three species of the genus Amphiesma Duméril, Bibron & Duméril, 1854 have long been confused in the literature, with each other and with other species of the genus. Amphiesma khasiense (Boulenger, 1890) has been considered to inhabit a large geographical region, extending from north-eastern India, east to Vietnam and southern Thailand. Amphiesma boulengeri (Gressitt, 1937) has been regarded as a species endemic to south-eastern China. Amphiesma inas (Laidlaw, 1901) has been recorded from West Malaysia, Thailand and Indonesia (Sumatra). A multivariate analysis of morphometric and meristic characters shows that these three species can be separated by combinations of characters in the scalation and pattern, the most obvious being the structure of the postocular streak. On the basis of our analysis and after comparison with name-bearing type specimens, Amphiesma khasiense is restricted to north-eastern India, Myanmar, western Yunnan Province of China, northern Laos and northern and western Thailand. Other populations from south-eastern China, Vietnam, other parts of Laos, Cambodia and central Thailand, which have been recorded in the literature as A. khasiense, A.johannis or Amphiesma modestum (Günther, 1875), should be referred to Amphiesma boulengeri. Amphiesma inas (Laidlaw, 1901) is a valid species endemic to mountain ranges of southern Peninsular Thailand and West Malaysia. The mention of Amphiesma inas in Sumatra is erroneous, being based on the second known specimen of Amphiesma kerinciense David & Das, 2003, which is here redescribed. A key to species of the Amphiesma khasiense group and other species sharing a greyish-brown background without conspicuous dark and pale stripes, is provided.
  12. Edible and Medicinal Mushrooms: Emerging Brain Food for the Mitigation of Neurodegenerative Diseases
    Phan CW, David P, Sabaratnam V
    J Med Food, 2017 Jan;20(1):1-10.
    PMID: 28098514 DOI: 10.1089/jmf.2016.3740
    There is an exponential increase in dementia in old age at a global level because of increasing life expectancy. The prevalence of neurodegenerative diseases such as dementia and Alzheimer's disease (AD) will continue to rise steadily, and is expected to reach 42 million cases worldwide in 2020. Despite the advancement of medication, the management of these diseases remains largely ineffective. Therefore, it is vital to explore novel nature-based nutraceuticals to mitigate AD and other age-related neurodegenerative disorders. Mushrooms and their extracts appear to hold many health benefits, including immune-modulating effects. A number of edible mushrooms have been shown to contain rare and exotic compounds that exhibit positive effects on brain cells both in vitro and in vivo. In this review, we summarize the scientific information on edible and culinary mushrooms with regard to their antidementia/AD active compounds and/or pharmacological test results. The bioactive components in these mushrooms and the underlying mechanism of their activities are discussed. In short, these mushrooms may be regarded as functional foods for the mitigation of neurodegenerative diseases.
  13. Fulltext The impact of selective-logging and forest clearance for oil palm on fungal communities in Borneo
    Kerfahi D, Tripathi BM, Lee J, Edwards DP, Adams JM
    PLoS One, 2014;9(11):e111525.
    PMID: 25405609 DOI: 10.1371/journal.pone.0111525
    Tropical forests are being rapidly altered by logging, and cleared for agriculture. Understanding the effects of these land use changes on soil fungi, which play vital roles in the soil ecosystem functioning and services, is a major conservation frontier. Using 454-pyrosequencing of the ITS1 region of extracted soil DNA, we compared communities of soil fungi between unlogged, once-logged, and twice-logged rainforest, and areas cleared for oil palm, in Sabah, Malaysia. Overall fungal community composition differed significantly between forest and oil palm plantation. The OTU richness and Chao 1 were higher in forest, compared to oil palm plantation. As a proportion of total reads, Basidiomycota were more abundant in forest soil, compared to oil palm plantation soil. The turnover of fungal OTUs across space, true β-diversity, was also higher in forest than oil palm plantation. Ectomycorrhizal (EcM) fungal abundance was significantly different between land uses, with highest relative abundance (out of total fungal reads) observed in unlogged forest soil, lower abundance in logged forest, and lowest in oil palm. In their entirety, these results indicate a pervasive effect of conversion to oil palm on fungal community structure. Such wholesale changes in fungal communities might impact the long-term sustainability of oil palm agriculture. Logging also has more subtle long term effects, on relative abundance of EcM fungi, which might affect tree recruitment and nutrient cycling. However, in general the logged forest retains most of the diversity and community composition of unlogged forest.
  14. Effectiveness of pharmacist-led medication review in chronic pain management: systematic review and meta-analysis
    Hadi MA, Alldred DP, Briggs M, Munyombwe T, Closs SJ
    Clin J Pain, 2014 Nov;30(11):1006-14.
    PMID: 24480911 DOI: 10.1097/AJP.0000000000000063
    OBJECTIVE: To evaluate the effectiveness of pharmacist-led medication review in chronic pain management.

    MATERIALS AND METHODS: Six electronic databases (Medline, Embase, PsycInfo, CINHAL, CENTRAL, International Pharmaceutical Abstracts) reference lists of retrieved articles and relevant websites were searched for randomized controlled trials published in the English language involving adults with chronic pain. Studies were included if one of the intervention arms had received pharmacist-led medication review independently or as part of a multidisciplinary intervention. Risk of bias was assessed for all the included studies.

    RESULTS: The search strategy yielded 583 unique articles including 5 randomized controlled trials. Compared with control, meta-analysis showed that participants in the intervention group had: a 0.8-point reduction in pain intensity on a 0 to 10 numerical rating scale at 3 months [95% confidence interval (CI), -1.28 to -0.36] and a 0.7-point reduction (95% CI, -1.19 to -0.20) at 6 months; a 4.84 point (95% CI, -7.38 to -2.29) and -3.82 point (95% CI, -6.49 to -1.14) improvement in physical functioning on a 0- to 68-point function subscale of Western Ontario and McMaster Universities Osteoarthritis Index at 3 and 6 months, respectively; and a significant improvement in patient satisfaction equivalent to a "small to moderate effect."

    DISCUSSION: Pharmacist-led medication review reduces pain intensity and improves physical functioning and patient satisfaction. However, the clinical significance of these findings remain uncertain due to small effect size and nature of reported data within clinical trials that limits recommendation of wider clinical role of pharmacist in chronic pain management.

  15. Fulltext Impacts of intensive logging on the trophic organisation of ant communities in a biodiversity hotspot
    Woodcock P, Edwards DP, Newton RJ, Vun Khen C, Bottrell SH, Hamer KC
    PLoS One, 2013;8(4):e60756.
    PMID: 23593302 DOI: 10.1371/journal.pone.0060756
    Trophic organisation defines the flow of energy through ecosystems and is a key component of community structure. Widespread and intensifying anthropogenic disturbance threatens to disrupt trophic organisation by altering species composition and relative abundances and by driving shifts in the trophic ecology of species that persist in disturbed ecosystems. We examined how intensive disturbance caused by selective logging affects trophic organisation in the biodiversity hotspot of Sabah, Borneo. Using stable nitrogen isotopes, we quantified the positions in the food web of 159 leaf-litter ant species in unlogged and logged rainforest and tested four predictions: (i) there is a negative relationship between the trophic position of a species in unlogged forest and its change in abundance following logging, (ii) the trophic positions of species are altered by logging, (iii) disturbance alters the frequency distribution of trophic positions within the ant assemblage, and (iv) disturbance reduces food chain length. We found that ant abundance was 30% lower in logged forest than in unlogged forest but changes in abundance of individual species were not related to trophic position, providing no support for prediction (i). However, trophic positions of individual species were significantly higher in logged forest, supporting prediction (ii). Consequently, the frequency distribution of trophic positions differed significantly between unlogged and logged forest, supporting prediction (iii), and food chains were 0.2 trophic levels longer in logged forest, the opposite of prediction (iv). Our results demonstrate that disturbance can alter trophic organisation even without trophically-biased changes in community composition. Nonetheless, the absence of any reduction in food chain length in logged forest suggests that species-rich arthropod food webs do not experience trophic downgrading or a related collapse in trophic organisation despite the disturbance caused by logging. These food webs appear able to bend without breaking in the face of some forms of anthropogenic disturbance.
  16. Reduced-impact logging and biodiversity conservation: a case study from Borneo
    Edwards DP, Woodcock P, Edwards FA, Larsen TH, Hsu WW, Benedick S, et al.
    Ecol Appl, 2012 Mar;22(2):561-71.
    PMID: 22611854 DOI: 10.1890/11-1362.1
    A key driver of rain forest degradation is rampant commercial logging. Reduced-impact logging (RIL) techniques dramatically reduce residual damage to vegetation and soils, and they enhance the long-term economic viability of timber operations when compared to conventionally managed logging enterprises. Consequently, the application of RIL is increasing across the tropics, yet our knowledge of the potential for RIL also to reduce the negative impacts of logging on biodiversity is minimal. We compare the impacts of RIL on birds, leaf-litter ants, and dung beetles during a second logging rotation in Sabah, Borneo, with the impacts of conventional logging (CL) as well as with primary (unlogged) forest. Our study took place 1-8 years after the cessation of logging. The species richness and composition of RIL vs. CL forests were very similar for each taxonomic group. Both RIL and CL differed significantly from unlogged forests in terms of bird and ant species composition (although both retained a large number of the species found in unlogged forests), whereas the composition of dung beetle communities did not differ significantly among forest types. Our results show little difference in biodiversity between RIL and CL over the short-term. However, biodiversity benefits from RIL may accrue over longer time periods after the cessation of logging. We highlight a severe lack of studies investigating this possibility. Moreover, if RIL increases the economic value of selectively logged forests (e.g., via REDD+, a United Nations program: Reducing Emissions from Deforestation and Forest Degradation in Developing Countries), it could help prevent them from being converted to agricultural plantations, which results in a tremendous loss of biodiversity.
  17. Fulltext The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants
    Woodcock P, Edwards DP, Fayle TM, Newton RJ, Khen CV, Bottrell SH, et al.
    Philos Trans R Soc Lond B Biol Sci, 2011 Nov 27;366(1582):3256-64.
    PMID: 22006966 DOI: 10.1098/rstb.2011.0031
    South East Asia is widely regarded as a centre of threatened biodiversity owing to extensive logging and forest conversion to agriculture. In particular, forests degraded by repeated rounds of intensive logging are viewed as having little conservation value and are afforded meagre protection from conversion to oil palm. Here, we determine the biological value of such heavily degraded forests by comparing leaf-litter ant communities in unlogged (natural) and twice-logged forests in Sabah, Borneo. We accounted for impacts of logging on habitat heterogeneity by comparing species richness and composition at four nested spatial scales, and examining how species richness was partitioned across the landscape in each habitat. We found that twice-logged forest had fewer species occurrences, lower species richness at small spatial scales and altered species composition compared with natural forests. However, over 80 per cent of species found in unlogged forest were detected within twice-logged forest. Moreover, greater species turnover among sites in twice-logged forest resulted in identical species richness between habitats at the largest spatial scale. While two intensive logging cycles have negative impacts on ant communities, these degraded forests clearly provide important habitat for numerous species and preventing their conversion to oil palm and other crops should be a conservation priority.
  18. The value of rehabilitating logged rainforest for birds
    Edwards DP, Ansell FA, Ahmad AH, Nilus R, Hamer KC
    Conserv Biol, 2009 Dec;23(6):1628-33.
    PMID: 19775274 DOI: 10.1111/j.1523-1739.2009.01330.x
    The recent advent of carbon crediting has led to a rapid rise in biosequestration projects that seek to remove carbon from the atmosphere through afforestation and forest rehabilitation. Such projects also present an important potential opportunity to reverse biodiversity losses resulting from deforestation and forest degradation, but the biodiversity benefits of different forms of biosequestration have not been considered adequately. We captured birds in mist nets to examine the effects of rehabilitation of logged forest on birds in Sabah, Borneo, and to test the hypothesis that rehabilitation restores avian assemblages within regenerating forest to a condition closer to that seen in unlogged forest. Species richness and diversity were similar in unlogged and rehabilitated forest, but significantly lower in naturally regenerating forest. Rehabilitation resulted in a relatively rapid recovery of populations of insectivores within logged forest, especially those species that forage by sallying, but had a marked adverse effect on frugivores and possibly reduced the overall abundance of birds within regenerating forest. In view of these results, we advocate increased management for heterogeneity within rehabilitated forests, but we strongly urge an increased role for forest rehabilitation in the design and implementation of a biodiversity-friendly carbon-offsetting market.
  19. The impact of tropical forest logging and oil palm agriculture on the soil microbiome
    Tripathi BM, Edwards DP, Mendes LW, Kim M, Dong K, Kim H, et al.
    Mol Ecol, 2016 May;25(10):2244-57.
    PMID: 26994316 DOI: 10.1111/mec.13620
    Selective logging and forest conversion to oil palm agriculture are rapidly altering tropical forests. However, functional responses of the soil microbiome to these land-use changes are poorly understood. Using 16S rRNA gene and shotgun metagenomic sequencing, we compared composition and functional attributes of soil biota between unlogged, once-logged and twice-logged rainforest, and areas converted to oil palm plantations in Sabah, Borneo. Although there was no significant effect of logging history, we found a significant difference between the taxonomic and functional composition of both primary and logged forests and oil palm. Oil palm had greater abundances of genes associated with DNA, RNA, protein metabolism and other core metabolic functions, but conversely, lower abundance of genes associated with secondary metabolism and cell-cell interactions, indicating less importance of antagonism or mutualism in the more oligotrophic oil palm environment. Overall, these results show a striking difference in taxonomic composition and functional gene diversity of soil microorganisms between oil palm and forest, but no significant difference between primary forest and forest areas with differing logging history. This reinforces the view that logged forest retains most features and functions of the original soil community. However, networks based on strong correlations between taxonomy and functions showed that network complexity is unexpectedly increased due to both logging and oil palm agriculture, which suggests a pervasive effect of both land-use changes on the interaction of soil microbes.
  20. Fulltext Selective logging in tropical forests decreases the robustness of liana-tree interaction networks to the loss of host tree species
    Magrach A, Senior RA, Rogers A, Nurdin D, Benedick S, Laurance WF, et al.
    Proc Biol Sci, 2016 Mar 16;283(1826):20153008.
    PMID: 26936241 DOI: 10.1098/rspb.2015.3008
    Selective logging is one of the major drivers of tropical forest degradation, causing important shifts in species composition. Whether such changes modify interactions between species and the networks in which they are embedded remain fundamental questions to assess the 'health' and ecosystem functionality of logged forests. We focus on interactions between lianas and their tree hosts within primary and selectively logged forests in the biodiversity hotspot of Malaysian Borneo. We found that lianas were more abundant, had higher species richness, and different species compositions in logged than in primary forests. Logged forests showed heavier liana loads disparately affecting slow-growing tree species, which could exacerbate the loss of timber value and carbon storage already associated with logging. Moreover, simulation scenarios of host tree local species loss indicated that logging might decrease the robustness of liana-tree interaction networks if heavily infested trees (i.e. the most connected ones) were more likely to disappear. This effect is partially mitigated in the short term by the colonization of host trees by a greater diversity of liana species within logged forests, yet this might not compensate for the loss of preferred tree hosts in the long term. As a consequence, species interaction networks may show a lagged response to disturbance, which may trigger sudden collapses in species richness and ecosystem function in response to additional disturbances, representing a new type of 'extinction debt'.
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