Publications by authors named "Rhett Harrison"

Article Synopsis
  • * When invertebrates are involved, wood breaks down about 40% faster, especially in tropical areas where termites are really active.
  • * The study shows that both the size of the wood and its outer layer affect how invertebrates and fungi work together to decompose it.
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Climate change and other anthropogenic disturbances are increasing liana abundance and biomass in many tropical and subtropical forests. While the effects of living lianas on species diversity, ecosystem carbon, and nutrient dynamics are receiving increasing attention, the role of dead lianas in forest ecosystems has been little studied and is poorly understood. Trees and lianas coexist as the major woody components of forests worldwide, but they have very different ecological strategies, with lianas relying on trees for mechanical support.

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Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge.

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Article Synopsis
  • Research on flowering plants has evolved from focusing solely on pollinator specificity to considering introgressive hybridization as a significant factor affecting species relationships.
  • A study on fig trees (Moraceae) uses extensive genetic sampling to explore phylogenetic ties and the role of hybridization among 520 species, revealing that local introgression occurs despite overall reproductive isolation.
  • Findings indicate that while hybridization contributes to plant evolution, strong plant-pollinator relationships can prevent ongoing hybridization between unrelated lineages, maintaining genetic stability in figs.
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Fall armyworm (Spodoptera frugiperda J. E. Smith), a serious pest of maize and other cereals, recently invaded the Old World potentially threatening the food security and incomes of millions of smallholder farmers.

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Fall armyworm (Spodoptera frugiperda Smith), a serious pest of cereals from the Americas, has spread across sub-Saharan Africa and Asia since 2016, threatening the food security and incomes of millions of smallholder farmers. To measure the impact of S. frugiperda under different management approaches, we established on-farm trials across 12 landscapes (615-1,379 mm mean annual rainfall) in Malawi and Zambia during the 2019/2020 and 2020/2021 seasons.

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The UN Decade on Ecosystem Restoration offers immense potential to return hundreds of millions of hectares of degraded tropical landscapes to functioning ecosystems. Well-designed restoration can tackle multiple Sustainable Development Goals, driving synergistic benefits for biodiversity, ecosystem services, agricultural and timber production, and local livelihoods at large spatial scales. To deliver on this potential, restoration efforts must recognise and reduce trade-offs among objectives, and minimize competition with food production and conservation of native ecosystems.

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Article Synopsis
  • The phylogeny of fig trees has been unclear despite previous sequencing efforts, which hinders the understanding of their evolutionary traits.
  • Researchers utilized restriction-site-associated DNA sequencing and morphological data from 70 Ficus species to clarify their relationships, revealing a new monophyletic subgenus and insights into the evolutionary history.
  • The study suggests that the ancestral form of fig trees was likely a freestanding tree with active pollination, promoting a return to morphological traits as crucial for understanding their evolution due to potential errors in large molecular datasets.
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The Cerambycidae comprise a large and ecologically important family of wood-boring beetles. The purpose of this study was to examine the effectiveness of a generic lure as a potential monitoring tool. Working in a subtropical forest in southwest China, we set traps baited with generic lures at ground level (1 m) and canopy height (~18 m) across 22 randomly located forest plots (12 regenerating forest, 10 mature forest).

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Fall armyworm (FAW), a voracious agricultural pest native to North and South America, was first detected on the African continent in 2016 and has subsequently spread throughout the continent and across Asia. It has been predicted that FAW could cause up to $US13 billion per annum in crop losses throughout sub-Saharan Africa, thereby threatening the livelihoods of millions of poor farmers. In their haste to respond to FAW governments may promote indiscriminate use of chemical pesticides which, aside from human health and environmental risks, could undermine smallholder pest management strategies that depend to a large degree on natural enemies.

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Deforestation has a substantial impact on aboveground biodiversity, but the response of belowground soil fungi remains poorly understood. In a tropical montane rainforest in southwestern China, plots were established along a forest degradation gradient ranging from mature and regenerated forests to open land to examine the impacts of forest degradation and deforestation on ecosystem diversity and function. Here, we evaluated the changes in belowground fungal diversity and community composition using a metabarcoding approach.

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The relationship between β-diversity and latitude still remains to be a core question in ecology because of the lack of consensus between studies. One hypothesis for the lack of consensus between studies is that spatial scale changes the relationship between latitude and β-diversity. Here, we test this hypothesis using tree data from 15 large-scale forest plots (greater than or equal to 15 ha, diameter at breast height ≥ 1 cm) across a latitudinal gradient (3-30) in the Asia-Pacific region.

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Article Synopsis
  • Understanding the biogeographic affinities of tropical forests helps explain regional differences in their structure, diversity, and responses to global changes.
  • The study classifies the world's tropical forests into five main floristic regions based on their phylogenetic relationships: Indo-Pacific, Subtropical, African, American, and Dry forests.
  • Findings challenge the traditional division of tropical forests and suggest a connection between northern-hemisphere Subtropical forests in Asia and America, as well as the existence of a global dry forest region.
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It is widely believed that aposematic signals should be conspicuous, but in nature, they vary from highly conspicuous to near cryptic. Current theory, including the honest signal or trade-off hypotheses of the toxicity-conspicuousness relationship, cannot explain why adequately toxic species vary substantially in their conspicuousness. Through a study of similarly toxic Danainae (Nymphalidae) butterflies and their mimics that vary remarkably in their conspicuousness, we show that the benefits of conspicuousness vary along a gradient of predation pressure.

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Ficus elastica, otherwise known as India Rubber (although its geographical origins are unclear), was an important source of latex in the early 19 century and was widely cultivated in tropical Asia. Like all figs, F. elastica is dependent on tiny, highly specific wasps for pollination, and detailed studies based out of Singapore in the 1930s suggested that through the loss of its pollinator F.

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The use of native species in forest restoration has been increasingly recognized as an effective means of restoring ecosystem functions and biodiversity to degraded areas across the world. However, successful selection of species adapted to local conditions requires specific knowledge which is often lacking, especially in developing countries. In order to scale up forest restoration, experimental data on the responses of native species to propagation and restoration treatments across a range of local conditions are required.

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Organic matter decomposition represents a vital ecosystem process by which nutrients are made available for plant uptake and is a major flux in the global carbon cycle. Previous studies have investigated decomposition of different plant parts, but few considered bark decomposition or its role in decomposition of wood. However, bark can comprise a large fraction of tree biomass.

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Plant diversity surely determines arthropod diversity, but only moderate correlations between arthropod and plant species richness had been observed until Basset et al. (Science, 338, 2012 and 1481) finally undertook an unprecedentedly comprehensive sampling of a tropical forest and demonstrated that plant species richness could indeed accurately predict arthropod species richness. We now require a high-throughput pipeline to operationalize this result so that we can (i) test competing explanations for tropical arthropod megadiversity, (ii) improve estimates of global eukaryotic species diversity, and (iii) use plant and arthropod communities as efficient proxies for each other, thus improving the efficiency of conservation planning and of detecting forest degradation and recovery.

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Although deforestation and forest degradation have long been considered the most significant threats to tropical biodiversity, across Southeast Asia (Northeast India, Indochina, Sundaland, Philippines) substantial areas of natural habitat have few wild animals (>1 kg), bar a few hunting-tolerant species. To document hunting impacts on vertebrate populations regionally, we conducted an extensive literature review, including papers in local journals and reports of governmental and nongovernmental agencies. Evidence from multiple sites indicated animal populations declined precipitously across the region since approximately 1980, and many species are now extirpated from substantial portions of their former ranges.

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During field screening trials of a number of known cerambycid pheromones in China, males of Megopis costipennis (White) (Coleoptera: Cerambycidae: Prioninae: Callipogonini) were found to be specifically attracted to racemic anti-2,3-octanediol, suggesting that one of the enantiomers of this compound might be a female-produced sex pheromone of this species. Analysis of volatiles produced by beetles of both sexes confirmed this hypothesis: females produced (2R,3S)-2,3-octanediol, whereas males did not, and in coupled gas chromatography–electroantennogram detection analyses, antennae from male beetles responded strongly to this compound. In field trials, males were equally attracted to traps baited with either (2R,3S)-2,3-octanediol or racemic anti-2,3-octanediol, indicating that the enantiomeric (2S,3R)-2,3-octanediol does not antagonize attraction to the naturally produced enantiomer.

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Plant functional traits reflect different evolutionary responses to environmental variation, and among extant species determine the outcomes of interactions between plants and their environment, including other plant species. Thus, combining phylogenetic and trait-based information can be a powerful approach for understanding community assembly processes across a range of spatial scales. We used this approach to investigate tree community composition at Phou Khao Khouay National Park (18°14'-18°32'N; 102°38'- 102°59'E), Laos, where several distinct forest types occur in close proximity.

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The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e.

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Vascular epiphytes are an understudied and particularly important component of tropical forest ecosystems. However, owing to the difficulties of access, little is known about the properties of epiphyte-host tree communities and the factors structuring them, especially in Asia. We investigated factors structuring the vascular epiphyte-host community and its network properties in a tropical montane forest in Xishuangbanna, SW China.

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The primary approach used to conserve tropical biodiversity is in the establishment of protected areas. However, many tropical nature reserves are performing poorly and interventions in the broader landscape may be essential for conserving biodiversity both within reserves and at large. Between October 2010 and 2012, we conducted bird surveys in and around a recently established nature reserve in Xishuangbanna, China.

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