Understanding general flowering and mast fruiting in Southeast Asia: research gaps and consequences for studying faunal communities

Evidence is mounting that flowering by the mast‐fruiting Dipterocarpaceae in Southeast Asia is triggered by ENSO events such that seeds are dispersed at the end of ENSO droughts. These droughts induce substantial defoliation and mortality of canopy trees, producing a favorable environment for seedling recruitment in the forest understory. Therefore, seedling release following droughts may have selected for synchronized, supra‐annual fruiting in these rain forests. Currently, mast fruiting in Southeast Asia is generally regarded as an evolutionary response to seed predation by nomadic vertebrates. Separating the two causes for mast fruiting, seedling release and predator satiation, may be difficult if they are coupled in nature by ENSO droughts. Nevertheless, if the cue for masting is environmental, then the post‐ENSO seedling environment should be considered a potential cause for masting, and if it operates in conjunction with predator satiation, then it may have provided the initial stimulus for supra‐annual synchrony in fruiting.

Abstract:South-East Asian tropical rain forests experience sporadic, but profuse, seed production after general flowering, leading to the synchronous emergence of various seedlings and subsequent seedling dynamics, which play a crucial role in determining species distribution and coexistence. We examined the relative importance of both biotic (initial height, conspecific seedling density) and abiotic (canopy openness, per cent sand, soil water content) drivers using survival data for 1842 seedlings of 12 dipterocarp species for 1.5 y following mast fruiting in an old-growth Bornean tropical rain forest. More than 30% of all dipterocarp seedlings survived 1.5 y after mast fruiting. When all species were analysed together, we found that initial seedling height, canopy openness and conspecific seedling density affected dipterocarp seedling survival. Negative density dependence indicated that predators were not satiated, but dipterocarp seedlings rather suffered from host-specific natural enemies or intraspecific competition. Species-level analyses of seven dipterocarp species showed large variation in response to biotic and abiotic factors. These results suggest that interspecific differences in the relative importance of biotic and abiotic effects on seedling survival might contribute to species coexistence.

* About the Editors * Contributors * Foreword (Paul E. Fixen) * Preface * Chapter 1. Global Food Production and Plant Nutrient Demand: Present Status and Future Prospects (Luc M. Maene, Kristen E. Sukalac, and Patrick Heffer) * Introduction * Trends in Global Food, Feed, and Fiber Production and Consumption * Trends in Global Nutrient Demand * Conclusions * Chapter 2. Integrated Nutrient Management: Present Status and Future Prospects (Cynthia A. Grant, Milkha S. Aulakh, and A. E. Johnny Johnston) * Introduction * The Challenge of Nutrient Depletion * The Challenge of Nutrient Excess * Challenges for Integrated Nutrient Management * Future Challenges * Chapter 3. Integrated Nutrient Management: Experience and Concepts from the United States (Mark M. Alley, Dwayne G. Westfall, and Gregory L. Mullins) * Introduction * Major Climatic Regions and Crop Production * Crop Production and Nutrient Removals in Harvests * Monitoring Soil Fertility Levels in the United States * Manure Nutrient Sources * Nutrient Use * Nutrient Sources and Soil Fertility Maintenance * Nutrient Management Plans * Research Needs * Chapter 4. Integrated Nutrient Management: Experience and Concepts from Canada (Sukhdev S. Malhi, Cynthia A. Grant, Denis A. Angers, Adrian M. Johnston, Jeff J. Schoenau, and Craig F. Drury) * Introduction * Major Soil/Climatic Regions and Cropping Systems * Agriculture Production and Nutrient Balances * Fertilizers and Sustainable Development * Technical Requirements for INM * Case Studies * Research Accomplishments, Gaps, and Future Needs * Conclusions * Chapter 5. Integrated Nutrient Management: The European Experience (Paolo Sequi, A. E Johnny Johnston, Rosa Francaviglia, and Roberta Farina) * Introduction * Background * Major Soil Classes, Climatic Zones, and Agricultural Production Systems * Agricultural Production, Nutrient Use, and Issues * Farming Practices and Environmental Issues * Integrated Nutrient Management and Agri-Environmental Policies * Appendix 1. * Appendix 2. * Appendix 3. * Chapter 6. Integrated Nutrient Management: Experience and Concepts from New Zealand (Antony H. C. Roberts, Tony J. van der Weerden, and Douglas C. Edmeades) * Introduction * Major Soil and Climatic Regions and Major Cropping Systems * Agricultural Production and Nutrient Balances * Fertilizers and Sustainable Development * Integrated Nutrient Management * Technical Requirements for INM * Actual Implementation and INM * Discussion of Cases * Research Gaps and Future Research Needs * Summary and Conclusion * Chapter 7. Integrated Nutrient Management: Experience from South Asia (Milkha S. Aulakh and Guriqbal Singh) * Introduction * Climate Major Crops * Agricultural Production and Nutrient Consumption * Benefits and Limitations of Chemical Fertilizers * Integrated Nutrient Management Practices * Technical Requirements for INM * Constraints for Implementation of INM * Research Gaps and Future Needs * Summary and Conclusions * Chapter 8. Integrated Nutrient Management: Experience from China (Bao Lin, Jianchang Xie, Ronggui Wu, Guangxi Xing, and Zhihong Li) * Introduction * Major Agricultural Regions and Cropping Systems * Agricultural Production, Fertilization, and Nutrient Balance * Integrated Nutrient Management (INM) * Benefits and Limitations of Chemical Fertilizers * Fertilizer and Agriculture Sustainability * Chapter 9. Integrated Nutrient Management: Experiences from Rice-Based Systems in Southeast Asia (Dan C. Olk, Mathias Becker, Bruce A. Linquist, Sushil Pandey, and Christian Witt) * Introduction * Integrated Nutrient Management in Rainfed Rice * Green Manures * Integrated Nutrient Management in Irrigated Lowland Rice * Socioeconomic Constraints to Adoption of Improved Nutrient Management Technologies * Conclusions * Chapter 10. Integrated Nutrient Management: Experience from South America (Bernardo van Raij, Alfredo Scheid Lopes, Eduardo Casanova, and Martin Diaz-Zorita) * Introduction * Main Ecosystems and Cropping Systems * Agricultural Production and Nutrient Balances * Fertilizers and Sustainable Development * Integrated Nutrient Management (INM) * Technical Requirements for INM * Actual Implementation of INM * Discussion of Cases * Research Gaps and Future Research Needs * Summary and Conclusion * Chapter 11. Integrated Nutrient Management: Concepts and Experience from Sub-Saharan Africa (Andre Bationo, Job Kihara, Bernard Vanlauwe, Joseph Kimetu, Boaz S. Waswa, and Kanwar L. Sahrawat) * Introduction * Overview of Soil Fertility Status in Africa * Evolution of Soil Fertility Paradigm in Africa * ISFM Experiences in SSA * Conclusions * Chapter 12. Integrated Nutrient Management: Experience and Concepts from the Middle East (Uzi Kafkafi and David J. Bonfil) * Introduction * Major Soils, Climatic Regions, and Major Cropping Systems * Agricultural Production and Nutrient Balance * Case Study of Wheat * Index * Reference Notes Included

Tropical forests are characterized by high biodiversity and aboveground biomass growing on strongly weathered soils. However, the distribution of plant species and soils are highly variable even within a tropical region. This paper reviews existing and novel knowledge on soil genesis, plant and microbial physiology, and biogeochemistry. Typically, forests in Southeast Asia are dominated by dipterocarps growing on acidic Ultisols from relatively young parent material. In the Neotropics and Africa, forests contain abundant legume trees growing on Oxisols developed in the older parent materials on stable continental shields. In Southeast Asia, the removal of base cations from the surface soil due to leaching and uptake by dipterocarp trees result in intensive acidification and accumulation of exchangeable Al3+, which is toxic to most plants. Nutrient mining by ectomycorrhizal fungi and efficient allocation within tree organs can supply phosphorus (P) for reproduction (e.g., mast fruiting) even on P-limited soils. In the Neotropics and Africa, nitrogen (N) fixation by legume trees can ameliorate N or P limitation but excess N can promote acidification through nitrification. Biological weathering [e.g., plant silicon (Si) cycling] and leaching can lead to loss of Si from soil. The resulting accumulation of Al and Fe oxides in Oxisols that can reduce P solubility through sorption and lead to limitation of P relative to N. Thus, geographical variation in geology and plant species drives patterns of soil weathering and niche differentiation at the global scale in tropical forests.

BackgroundSchizophrenia research has significantly grown in the past years. However, there is no comprehensive evaluation of schizophrenia research publications from Southeast Asia (SEA). Thus, this study determined the characteristics and trends of published articles about schizophrenia in SEA through a bibliometric analysis. MethodsA database search on schizophrenia research in SEA countries was performed using the Scopus databases from 1973 to 2021. Bibliometric information was obtained from Scopus, and network visualization was conducted using VOSviewer software. ResultsThere were 1068 articles on schizophrenia from SEA from 1973 until 2021. Schizophrenia research outputs from SEA started to increase from 2000 onwards. Singapore, Malaysia, and Thailand were the most productive countries in schizophrenia research and had the most collaborations. Most schizophrenia research in SEA was published in Asia- or SEA-based journals. The research hotspots for schizophrenia in SEA included treatment, pathophysiology, symptomatology, and psychological and social aspects of schizophrenia. Lastly, correlation analysis showed that gross domestic product per capita, research and development (R&D) expenditures, number of researchers in R&D, number of physicians, and international research collaborations were significantly correlated with higher research productivity and scientific impact in schizophrenia research. ConclusionIn conclusion, this study showed the trends and gaps for research in SEA and the socioeconomic factors correlated with research productivity for schizophrenia in SEA. This study emphasized increasing financial support and collaborations for schizophrenia research to improve research productivity in schizophrenia in the SEA region.

Climatic factors have commonly been attributed as the trigger of general flowering, a unique community-level mass flowering phenomenon involving most dipterocarp species that forms the foundation of Southeast Asian tropical rainforests. This intriguing flowering event is often succeeded by mast fruiting, which provides a temporary yet substantial burst of food resources for animals, particularly frugivores. However, the physiological mechanism that triggers general flowering, particularly in dipterocarp species, is not well understood largely due to its irregular and unpredictable occurrences in the tall and dense forests. To shed light on this mechanism, we employed ecological transcriptomic analyses on an RNA-seq dataset of a general flowering species, Shorea curtisii (Dipterocarpaceae), sequenced from leaves and buds collected at multiple vegetative and flowering phenological stages. We assembled 64,219 unigenes from the transcriptome of which 1,730 and 3,559 were differentially expressed in the leaf and the bud, respectively. Differentially expressed unigene clusters were found to be enriched with homologs of Arabidopsis thaliana genes associated with response to biotic and abiotic stresses, nutrient level, and hormonal treatments. When combined with rainfall data, our transcriptome data reveals that the trees were responding to a brief period of drought prior to the elevated expression of key floral promoters and followed by differential expression of unigenes that indicates physiological changes associated with the transition from vegetative to reproductive stages. Our study is timely for a representative general flowering dipterocarp species that occurs in forests that are under the constant threat of deforestation and climate change as it pinpoints important climate sensitive and flowering-related homologs and offers a glimpse into the cascade of gene expression before and after the onset of floral initiation.

Abstract:The Dipterocarpaceae in South-East Asia are known for their strict mast fruiting. During fruiting, pre-dispersal seed predation by insects contributes to mortality of dipterocarp seeds. We documented the community structure of insect seed predators on 11Shoreaspecies in Peninsular Malaysia. Fruits were sampled sequentially throughout seed development, and 2144 and 1655 individuals of seed predator weevils and moths were collected in two mast-fruiting events. Four weevils:Nanophyes shoreae, nanophyid sp. 1,Alcidodes dipterocarpiandAlcidodes humeralis, and one mothAndrioplecta shoreaewere abundant in seeds of theShoreaspecies. The proportion ofN. shoreaeto the total predators became larger in the latter fruiting event than the former while that ofAlcidodesspp. became smaller. The predator species composition changed during seed development; nanophyid spp. emerged from immature fruits whileAlcidodesspp. emerged from mature fruits.Andrioplecta shoreaeemerged from both immature and mature fruits. The level of host specificity measured by Kullback–Leibler distance was low for most predator species in both events. Predator species composition of manyShoreawas similar to each other due to the dominance ofN. shoreaethough it might gradually differ with the phylogenetic distance between hosts. In conclusion, predator species composition ofShoreavaried during seed development within a host rather than among hosts. Intermittent synchronized fruiting by congenericShoreatrees would be advantageous to avoid pre-dispersal insect seed predators, and contribute to their reproduction.

Knowledge of niche partitioning with respect to habitat is indispensable to understand the mechanism of coexistence of multiple species. Among primates, however, data are still deficient because repeated survey for a sufficiently long time, covering seasonal changes over a large area, is the only way to clarify habitat segregation within a seasonally fluctuating environment. Southeast Asia is particularly interesting because of the supra-annual, highly unpredictable seasonality in fruiting known as mast fruiting. We conducted repeated route census, habitat monitoring, and group tracking for 25 months in two study sites (ca. 10 km apart) in the largely primary lowland dipterocarp forest of the Danum Valley Conservation Area, eastern Sabah, northern Borneo, Malaysia. The five species of diurnal primates (Bornean orangutan Pongo pygmaeus, Müeller's gibbon Hylobates muelleri, red leaf monkey Presbytis rubicunda, long-tailed macaque Macaca fascicularis, and southern pig-tailed macaque M. nemestrina) did not show horizontal spatial segregation. Red leaf monkeys showed preferences for places with short tree height, but their distribution was not confined to such places. In response to the fruiting peak observed once during the study period, orangutans increased their numbers simultaneously in the two study sites. The average tree height used by the five species was different, but their range overlapped substantially. Compared with other primate communities, the lack of horizontal spatial segregation and the suggested long-distance movement of orangutans seem to be unique characteristics in Borneo, although the use of different forest strata is a widespread phenomenon among primate communities throughout the world.

Periods of extreme food abundance, such as irregular masting events, can dramatically affect animal populations and communities, but the extent to which anthropogenic disturbances alter animal responses to mast events is not clear. In South-East Asia, dipterocarp trees reproduce in mast fruiting events every 2-10years in some of the largest masting events on the planet. These trees, however, are targeted for selective logging, reducing the intensity of fruit production and potentially affecting multiple trophic levels. Moreover, animal responses to resource pulse events have largely been studied in systems where the major mast consumers have been extirpated. We sought to evaluate the influence of human-induced habitat disturbance on animal responses to masting in a system where key mast consumers remain extant. We used motion-triggered camera traps to quantify terrestrial mammal and bird occurrences in Sabah, Malaysian Borneo, relative to variation in fruit biomass from 69 plant families during a major (2014) and minor (2015) masting event and a non-mast year (2013), in both logged and unlogged forests. Bearded pigs (Sus barbatus) showed the clearest responses to masting and occurrence rates were highest in unlogged forest in the year following the major mast, suggesting that the pulse in fruit availability increased immigration or reproduction. We also detected local-scale spatial tracking of dipterocarp fruits in bearded pigs in unlogged forest, while this was equivocal in other species. In contrast, pigs and other vertebrate taxa in our study showed limited response to spatial or temporal variation in fruit availability in logged forest. Our findings suggest that vertebrates, namely bearded pigs, may respond to masting via movement and increased reproduction, but that these responses may be attenuated by habitat disturbance.

ABSTRACTOld‐growth forests in Southeast Asia are dominated by trees of the Dipterocarpaceae family which are targeted by selective logging. Their traits (supra‐annual mast fruiting, limited dispersal, and recalcitrant seeds that form no seed bank) mean they can have poor natural regeneration rates in some selectively logged forests. Enrichment planting is used to attempt to overcome this recruitment limitation and increase restoration success. However, it is still unclear what factors influence the performance of planted seedlings. Here, we analyse the growth and survival between 2012 and 2015 of 721 enrichment line‐planted seedlings from 16 species of dipterocarps within the selectively logged forest of the Sabah Biodiversity Experiment, alongside the location, size and identity of nearly 5000 naturally occurring trees within 10 m of focal planted seedlings. We analysed the survival and growth of enrichment planted dipterocarp seedlings in relation to three properties of the surrounding naturally occurring vegetation: (1) canopy openness; (2) the abundance of naturally occurring dipterocarps (proportion of total basal area); (3) the presence of nearby (< 10 m) large trees (basal area of the largest tree as a proportion of the total). Survival and growth rates of enrichment planted seedlings were positively associated with canopy openness and total basal area of surrounding trees. These results were consistent between the two planting cohorts. Increased survival and growth of enrichment planted seedlings in areas of Sabah Biodiversity Experiment with higher canopy openness (up to around 40%) is consistent with understory light as a limiting resource. The unexpected higher survival and growth of enrichment planted seedlings in forest areas with higher basal area of unlogged trees may be explained by the creation of patches that are better or worse for tree growth, with areas less heavily impacted by logging containing both more naturally occurring trees and providing better conditions for the survival and growth of planted seedlings.

Understanding wildlife spatiotemporal dynamics at protected area boundaries is critical to conservation. In SE Asia, protected areas are often bordered by indigenous communities whose traditional practices result in increased landscape heterogeneity within their community managed forests (CF). Because SE Asian forests exhibit supra‐annual mast fruiting (3–7 yrs) and sustained fruit scarcity, wildlife using CF may benefit from greater availability of fruits and seeds encouraged by traditional management, but incur greater risk of being hunted. We examined shifts in wildlife activity in forests within and adjacent to Lanjak Entimau Wildlife Sanctuary (LEWS), in Sarawak, Malaysia. Using camera traps and surveys of fruiting phenology, we related presence of fruits and seeds to shifts in large mammal activity over 3 years (October 2016–2019). We first compared relative frequency of five focal species (sun bear, bearded pig, muntjac, mouse deer, and sambar) by forest type for a given survey year and season (rainy vs. dry). We then modeled activity to assess how fruit availability, landscape features, and proxies for hunting risk, influence seasonal shifts in habitat use. Our results suggested seasonal variation in concert with increased landscape heterogeneity influenced patterns of activity. We found no evidence that CF excluded any detected mammal species, suggesting CF contribute important habitat to wildlife, particularly during periods of fruit scarcity in primary forest. However, our findings also imply increased hunting risk for wildlife attracted to resources near human settlements, emphasizing the need to consider the influence of both annual and supra‐annual seasonality when developing best practices for the sustainable management.

The general flowering (GF) events of forests in south-east Asia are perhaps the most spectacular phenomena in tropical biology. GF events occur at multiyear intervals. In GF, most dipterocarp species and many plants of other families come into flower and set fruit massively; these species and plants rarely flower except during GF events. GF is unique, because it can occur over thousands of kilometers and involve hundreds of plant species representing diverse families and lifeforms. It also involves strict mast fruiting. Satiation of generalist seed predators has been considered a primary force for GF. However, recent observations indicate that several selective agents rather than a single major factor may shape GF. In addition to the satiation of generalist predators, promotion of pollination could be one of the selective factors for GF, since synchronized flowering of many species causes an increase in pollinator activity through immigration and population growth. Although environmental prediction for better establishment of seedlings may also be involved in GF, no field data have been reported to support this idea. Long-term monitoring and further understanding of GF are essential for the conservation of this unique and diverse tropical forest in south-east Asia, especially in a period of global climatic change. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 233–247.

A scoping review of antibiotic use practices and drivers of inappropriate antibiotic use in animal farms in WHO Southeast Asia region

Question: The evolution of general flowering and mast fruiting of dipterocarps in tropical rain forest has been explained by different mechanisms. We studied whether the abundance of flowering conspecifics influences the recruitment success of tropical forest trees in Borneo. Location: Sepilok Forest Reserve, Sabah, Malaysia. Method: We examined the recruitment success of 17 species of Dipterocarpaceae in a 640-ha sample area over two flowering events in 2001–2002 using seed traps and quadrats. Seed predation experiments were used to investigate if post-dispersal seed survival was density-dependent. Results: We found a negative relationship between the percentage of flowers abscised per individual and the number of flowering conspecifics and a positive relationship between the percent of flowering trees that produced viable seeds and the number of flowering conspecifics. However, we found no evidence of decreasing pre- and post-dispersal predation with increasing numbers of flowering conspecifics. High levels of flower abscission, and pre- and post-dispersal seed mortality, resulted in near-complete recruitment failure of most species, with only three species successfully recruiting in only one year. One of these, Parashorea tomentella, satiated seed predators over a large area, while Hopea beccariana and Shorea multiflora only recruited in small isolated clumps. Seed predation experiments suggest that post-dispersal seed survival was positively density-dependent in the short-term. Conclusions: Increased density of flowering conspecifics may contribute to increased likelihood of successful cross-pollination during low intensity flowering events and, in some cases, to enhanced probability of short-term seed and seedling survival. Both processes may contribute to the evolution of mast fruiting and general flowering in Southeast Asian lowland dipterocarp forests.

Question:The evolution of general flowering and mast fruiting of dipterocarps in tropical rain forest has been explained by different mechanisms. We studied whether the abundance of flowering conspecifics influences the recruitment success of tropical forest trees in Borneo.Location:Sepilok Forest Reserve, Sabah, Malaysia.Method:We examined the recruitment success of 17 species ofDipterocarpaceaein a 640–ha sample area over two flowering events in 2001–2002 using seed traps and quadrats. Seed predation experiments were used to investigate if post‐dispersal seed survival was density‐dependent.Results:We found a negative relationship between the percentage of flowers abscised per individual and the number of flowering conspecifics and a positive relationship between the percent of flowering trees that produced viable seeds and the number of flowering conspecifics. However, we found no evidence of decreasing pre‐ and post‐dispersal predation with increasing numbers of flowering conspecifics. High levels of flower abscission, and pre‐ and post‐dispersal seed mortality, resulted in near‐complete recruitment failure of most species, with only three species successfully recruiting in only one year. One of these,Parashorea tomentella, satiated seed predators over a large area, whileHopea beccarianaandShorea multifloraonly recruited in small isolated clumps. Seed predation experiments suggest that post‐dispersal seed survival was positively density‐dependent in the short‐term.Conclusions:Increased density of flowering conspecifics may contribute to increased likelihood of successful cross‐pollination during low intensity flowering events and, in some cases, to enhanced probability of short‐term seed and seedling survival. Both processes may contribute to the evolution of mast fruiting and general flowering in Southeast Asian lowland dipterocarp forests.