Tropical Rainforest Biome Research Articles

A systematic map of evidence on the relationship between agricultural production and biodiversity in tropical rainforest areas

BackgroundThe tropical rainforest biome plays a significant role in providing habitats for terrestrial biodiversity and delivering ecosystem service values, contributing to agricultural production. However, the increasing demand for tropical commodities with high economic value threatens this humid ecosystem and its biodiversity. To our knowledge, no studies have systematically mapped the relationship between the impacts of agricultural production on biodiversity and the effects of biodiversity on agricultural production in tropical rainforest areas.MethodsSince we were interested in systematically mapping the evidence measuring the impact of tropical agriculture on biodiversity (Map 1), and the vice versa relations, the influence of biodiversity on tropical agriculture production (Map 2), we developed a respective set of search strings, eligibility criteria, and subsequently performed independent searching, screening, and data coding processes. We searched articles from six peer-reviewed databases and 22 gray literature sources. Articles were screened based on the inclusion criteria at the title, abstract, and full-text levels. Individual articles that passed full-text screening were coded and synthesized to create heatmaps. Selected information of interest was also extracted and visualized in the graphics which were clustered based on the year of publication, geographical distribution, type of rainforest, exposure, outcome, farm commodity, and study comparators.Review findingsTwo heatmaps were generated from a contrasting number of references, with heatmap 1 extracted from 222 studies and heatmap 2 derived from 10 times fewer references (n = 20). In heatmap 1, impacts of land conversion to aboveground biodiversity and wild species and ecosystem functions in natural ecosystems were the most common relationships examined, with 115 articles and 62 articles, respectively. Conversely, heatmap 2 showed evidence that focused predominantly on the examination of the links between the impacts of genetic resource diversity on environmental factors and soil management in tropical agricultural production, with four articles each exploring these relations.ConclusionsThese systematic maps reveal that while studies investigating the impacts of tropical agricultural production on biodiversity were abundant, studies examining the impacts of biodiversity on tropical agricultural production were lacking despite both systematic maps experiencing an increasing trend of publication during 2000–2020. Map 1 emphasized the examination of the effects of land conversion on aboveground biodiversity, and on wild species and ecosystem functions. Map 2 highlighted the influence of crop genetic resources on environmental factors, and on soil management as the most frequently studied. The evidence cluster identified here can be the starting point for further systematic review study (to assess, for example, their cause–effect significance).

PLANT COMMUNITY CHANGE ACROSS THE PALEOCENE–EOCENE BOUNDARY IN THE GULF COASTAL PLAIN, CENTRAL TEXAS

Abstract Long-term global warming during the early Paleogene was punctuated by several short-term ‘hyperthermal’ events, the most pronounced being the Paleocene–Eocene Thermal Maximum (PETM). During this long-term warming, tropical climates expanded into extra-tropical areas, creating a widespread band of thermophilic flora that reached into the paratropics, possibly as far north as mid-latitude North America in some regions. Relatively little is known about these paratropical floras, despite distribution across the North American Gulf Coastal Plain. We assess floras from the Gulf Coastal Plain in Central Texas before and after the Paleocene–Eocene boundary to define plant ecosystem changes associated with rapid global warming in this region. After the Paleocene–Eocene boundary, these floras suggest uniform plant communities across the Gulf Coastal Plain, but with high turnover rate and changes in community composition. Paleoecology and paleoclimate assessments from Central Texas Paleocene and Eocene floras suggest a warm and wet environment, indicative of tropical seasonal forest to tropical rainforest biomes. Fossil evidence from the Gulf Coastal Plain combined with the Bighorn Basin, Wyoming data suggest that early Paleogene warming helped create a paratropical belt that extended into mid-latitudes. Evaluating the response of fossil plant communities to rapid global warming has important implications for understanding and preparing for current global warming and climate change.

The emergence of the tropical rainforest biome in the Cretaceous

Abstract. Modern tropical rainforests (TRFs) are one of the most ecologically important and species-rich biomes on the planet. However, the origin of modern TRFs is still debated, especially due to the incongruence between the fossil record and molecular data. Here, we test whether Campanian assemblages from northeastern Africa could represent fossil TRF vegetation. In so doing, we compare the investigated assemblages with other assemblages known to represent temperate forests, subtropical forests, and TRF in terms of leaf physiognomy, species richness, and taxonomic composition. We conclude based on fossil leaves that modern-looking TRFs already existed since 80 Ma during the Campanian in northeastern Africa in an area corresponding to 10 % of the modern Amazonian or 25 % of the Congolese TRF. The apparent conflict between the fossil record and phylogenetic evidence is due to the nearly complete absence of published tropical floras for the Cretaceous.

Spatial and temporal variations of gross primary production simulated by land surface model BCC_AVIM2.0

Gross primary production (GPP) is the largest flux and a crucial player in the terrestrial carbon cycle and has been studied extensively, yet large uncertainties remain in the spatiotemporal patterns of GPP in both observations and simulations. This study evaluates the performance of the second version of the Beijing Climate Center Atmosphere−Vegetation Interaction Model (BCC_AVIM2.0) in simulating GPP on multiple spatial and temporal scales in the Coupled Model Intercomparison Project Phase 6 (CMIP6) experiments. Model simulations driven by two meteorological datasets were compared with two observation-based GPP products covering 1982–2008. Spatial patterns of annual GPP show a significant latitudinal gradient in each dataset, increasing from cold (tundra) and dry (desert) biomes to warm (temperate) and humid (tropical rainforest) biomes. BCC_AVIM2.0 overestimates GPP in most parts of the globe, especially in boreal forest regions and Southeast China, while underestimating GPP in subhumid regions in eastern South America and tropical Africa. The four datasets broadly agree on the GPP seasonal cycle, but BCC_AVIM2.0 predicts an earlier beginning of spring growth and a larger amplitude of seasonal variations than those in the observations. The observation-based datasets exhibit slight interannual variability (IAV) and weak GPP linear trends, while the BCC_AVIM2.0 simulations demonstrate relatively large year-to-year variability and significant trends in the low-latitudes and temperate monsoon regions in North America and East Asia. Regarding the possible relationships between annual means of GPP and climate factors, BCC_AVIM2.0 predicts more extensive regions of the globe where the IAV of annual GPP is dominated by precipitation, especially in mid-to-high latitudes of the Northern Hemisphere and tropical Africa, while the observed GPP in the above regions is temperature- or radiation-dominant. The positive GPP biases due to earlier spring growth in boreal forest regions and negative GPP biases in off-equator tropical areas in the BCC_AVIM2.0 simulations imply that cold stress on biomes in boreal mid-to-high latitudes should be strengthened to restrain plant growth, while drought stress in low-latitude regions might be eased to enhance plant production in the future version of BCC_AVIM.

Global Distribution of Aedes aegypti and Aedes albopictus in a Climate Change Scenario of Regional Rivalry.

Arboviral mosquito vectors are key targets for the surveillance and control of vector-borne diseases worldwide. In recent years, changes to the global distributions of these species have been a major research focus, aimed at predicting outbreaks of arboviral diseases. In this study, we analyzed a global scenario of climate change under regional rivalry to predict changes to these species' distributions over the next century. Using occurrence data from VectorMap and environmental variables (temperature and precipitation) from WorldClim v. 2.1, we first built fundamental niche models for both species with the boosted regression tree modelling approach. A scenario of climate change on their fundamental niche was then analyzed. The shared socioeconomic pathway scenario 3 (regional rivalry) and the global climate model Geophysical Fluid Dynamics Laboratory Earth System Model v. 4.1 (GFDL-ESM4.1; gfdl.noaa.gov) were utilized for all analyses, in the following time periods: 2021-2040, 2041-2060, 2061-2080, and 2081-2100. Outcomes from these analyses showed that future climate change will affect Ae. aegypti and Ae. albopictus distributions in different ways across the globe. The Northern Hemisphere will have extended Ae. aegypti and Ae. albopictus distributions in future climate change scenarios, whereas the Southern Hemisphere will have the opposite outcomes. Europe will become more suitable for both species and their related vector-borne diseases. Loss of suitability in the Brazilian Amazon region further indicated that this tropical rainforest biome will have lower levels of precipitation to support these species in the future. Our models provide possible future scenarios to help identify locations for resource allocation and surveillance efforts before a significant threat to human health emerges.

A time relic: a new species of dwarf boa, Tropidophis Bibron, 1840 (Serpentes: Amerophidia), from the Upper Amazon Basin

The amerophidian snake radiation is a Late Cretaceous superfamily that encompasses two families: Aniliidae, pipe snakes, and Tropidophiidae, dwarf boas. We describe a new dwarf boa snake species, from the Tropidophiidae family, from the cloud forest in northeastern Ecuador. Tropidophis cacuangoae sp. nov. can be diagnosed from its congeners based on external and osteological morphology. The new species inhabits eastern tropical piedmont and lower evergreen montane forests, in the Amazon Tropical Rainforest biome, and is likely to be an Ecuadorian endemic. We also discuss the relationships of the new species with South American tropidophiids and provide a key to the identification of mainland South American dwarf boas.

Implications of zero-deforestation palm oil for tropical grassy and dry forest biodiversity.

Many companies have made zero-deforestation commitments (ZDCs) to reduce carbon emissions and biodiversity losses linked to tropical commodities. However, ZDCs conserve areas primarily based on tree cover and aboveground carbon, potentially leading to the unintended consequence that agricultural expansion could be encouraged in biomes outside tropical rainforest, which also support important biodiversity. We examine locations suitable for zero-deforestation expansion of commercial oil palm, which is increasingly expanding outside the tropical rainforest biome, by generating empirical models of global suitability for rainfed and irrigated oil palm. We find that tropical grassy and dry forest biomes contain >50% of the total area of land climatically suitable for rainfed oil palm expansion in compliance with ZDCs (following the High Carbon Stock Approach; in locations outside urban areas and cropland), and that irrigation could double the area suitable for expansion in these biomes. Within these biomes, ZDCs fail to protect areas of high vertebrate richness from oil palm expansion. To prevent unintended consequences of ZDCs and minimize the environmental impacts of oil palm expansion, policies and governance for sustainable development and conservation must expand focus from rainforests to all tropical biomes.

Influence of the intertropical convergence zone on early cretaceous plant distribution in the South Atlantic

The influence of the Intertropical Convergence Zone (ITCZ) in the emerging South Atlantic region during the late Aptian (Early Cretaceous) is reflected in the spatio-temporal distribution of plant communities recorded in eight Brazilian sedimentary basins. The distribution of the bioclimatic groups of hygrophytes, hydrophytes, tropical lowland flora, upland flora, and xerophytes was quantified using pollen and spores. A predominance of xerophytes from the tropical xerophytic shrubland biome characterized the pre-evaporitic, evaporitic, and post-evaporitic paleoclimatic phases, in particular the evaporitic phase. The region experienced humidity events in the pre-evaporitic and post- evaporitic phases, especially near the paleoequator, where the tropical rainforest biome with two phytophysiognomies (lowland and montane rainforests) prevailed. Increasing humidity had a positive effect on plant diversity.

Land systems\u2019 asymmetries across transnational ecoregions in South America

The landscape configuration of socio-ecological land systems results from the interaction between the environmental conditions (relatively homogeneous within ecoregions) and country-level management and land-use decisions. However, social, land-use and sustainability research disciplines often study each independently. We used Euclidean distance analyses of five indicators of land systems functioning to explore the geographical patterns of across-border human-induced asymmetries in transnational ecoregions of South America. The most asymmetric transnational ecoregions occurred in the tropical rainforest biome which also showed the widest range of asymmetry values compared to other biomes. In contrast, transnational ecoregions in montane grasslands showed comparatively little asymmetries, and tropical dry forests showed intermediate asymmetry values. This pattern indicates that major asymmetries occur in land systems located in productive biomes with a comparatively recent history of development, whereas mature socio-ecosystems with a long history of human land use are more homogeneous across borders. In some cases, asymmetries may stabilize as a consequence of reinforcing feedbacks that promote contrasting land-use decisions across borders, including, for example, the establishment of protected areas, or the promotion of agro-industrial activities. Transnational socio-ecological land systems can be used to evaluate alternatives for sustainable development because they highlight the influence of institutions under different governance regimes in defining the spatial configuration and ecological properties of regions. We invite land-use and sustainability scientists to consider political border interactions as valuable “natural experiments” to better understand the interrelations between biophysical and political systems in defining planetary geographical-ecology in the Anthropocene.

The diversity ofSmilax(Smilacaceae) leaves from the Middle Miocene in southeastern China

The Fotan flora represents a tropical rainforest biome and is known by its abundance of fossil plant remains, which mainly include leaves and fruits. In this article, we describe threeSmilax(Smilacaceae) fossil taxa,S. fujianensissp. nov.,S. zhangpuensissp. nov., andSmilaxsp., from the Middle Miocene of Fujian Province, in southeastern China. Three morphotypes were examined for their gross morphological characteristics and cuticular structures, with especial reference to the venation patterns and stomata complexes. These new Miocene species increase the known diversity of the genusSmilaxin low‐latitude regions and contribute to a better understanding of its interspecific variability.Smilaxis sensitive to climatic change, and their spatial and temporal distribution fluctuates in response to the periods of warming or cooling in the Cenozoic. Moreover,Smilaxprimarily grows in warm and moist forests.

The surface-atmosphere exchange of carbon dioxide in tropical rainforests: Sensitivity to environmental drivers and flux measurement methodology

Tropical rainforests play a central role in the Earth system by regulating climate, maintaining biodiversity, and sequestering carbon. They are under threat by direct anthropogenic impacts like deforestation and the indirect anthropogenic impacts of climate change. A synthesis of the factors that determine the net ecosystem exchange of carbon dioxide (NEE) at the site scale across different forests in the tropical rainforest biome has not been undertaken to date. Here, we study NEE and its components, gross ecosystem productivity (GEP) and ecosystem respiration (RE), across thirteen natural and managed forests within the tropical rainforest biome with 63 total site-years of eddy covariance data. Our results reveal that the five ecosystems with the largest annual gross carbon uptake by photosynthesis (i.e. GEP > 3000 g C m−2 y-1) have the lowest net carbon uptake – or even carbon losses – versus other study ecosystems because RE is of a similar magnitude. Sites that provided subcanopy CO2 storage observations had higher average magnitudes of GEP and RE and lower average magnitudes of NEE, highlighting the importance of measurement methodology for understanding carbon dynamics in ecosystems with characteristically tall and dense vegetation. A path analysis revealed that vapor pressure deficit (VPD) played a greater role than soil moisture or air temperature in constraining GEP under light saturated conditions across most study sites, but to differing degrees from -0.31 to -0.87 μmol CO2 m−2 s-1 hPa-1. Climate projections from 13 general circulation models (CMIP5) under the representative concentration pathway that generates 8.5 W m−2 of radiative forcing suggest that many current tropical rainforest sites on the lower end of the current temperature range are likely to reach a climate space similar to present-day warmer sites by the year 2050, warmer sites will reach a climate not currently experienced, and all forests are likely to experience higher VPD. Results demonstrate the need to quantify if and how mature tropical trees acclimate to heat and water stress, and to further develop flux-partitioning and gap-filling algorithms for defensible estimates of carbon exchange in tropical rainforests.

Scientific approach as an understanding and applications of hydrological concepts of tropical rainforest

East Kalimantan has a variety of biomes, one of which is tropical rain forests. Tropical rain forests have enormous hydrological potential, so it is necessary to provide understanding to prospective teachers. Hydrology material cannot be separated from the concept of science, for it is needed the right way of learning so students easily understand the material. This research uses descriptive method with research subject is geography education students taking hydrology course at Faculty of Teacher Training and Education, Mulawarman University. The results showed that the students were able to observe, ask question, collect data, give reason, and communicate the hydrological conditions of tropical rain forest biomes, especially related to surface ground water and groundwater conditions. Tropical rainforests are very influenced by the hydrological conditions of the region and the availability of water is affected by the forest area as a catchment area. Therefore, the tropical rainforest must be maintained in condition and its duration, so that there is no water crisis and hydrological related disasters.

Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome

I. II. III. IV. V. VI. VII. VIII. IX. References SUMMARY: Tropical rainforest (TRF) is the most species-rich terrestrial biome on Earth, harbouring just under half of the world's plant species in c. 7% of the land surface. Phylogenetic trees provide important insights into mechanisms underpinning TRF hyperdiversity that are complementary to those obtained from the fossil record. Phylogenetic studies of TRF plant diversity have mainly focused on whether this biome is an evolutionary 'cradle' or 'museum', emphasizing speciation and extinction rates. However, other explanations, such as biome age, immigration and ecological limits, must also be considered. We present a conceptual framework for addressing the drivers of TRF diversity, and review plant studies that have tested them with phylogenetic data. Although surprisingly few in number, these studies point to old age of TRF, low extinction and high speciation rates as credible drivers of TRF hyperdiversity. There is less evidence for immigration and ecological limits, but these cannot be dismissed owing to the limited number of studies. Rapid methodological developments in DNA sequencing, macroevolutionary analysis and the integration of phylogenetics with other disciplines may improve our grasp of TRF hyperdiversity in the future. However, such advances are critically dependent on fundamental systematic research, yielding numerous, additional, well-sampled phylogenies of TRF lineages.

A new edition for Ecology of North America

book reviews frontiers of biogeography 8.4, e31122, 2016 A new edition for Ecology of North America Ecology of North America (2nd edn). Brian R. Chapman and Eric G. Bolen John Wiley & Sons, Ltd. 2015, 334 pp. ISBN13: 9781118971543 www.wiley.com/wiley-blackwell The disciplines of ecology and biogeography are so closely intertwined that many scholars of these respective fields are, by necessity and shared in- terest, well versed in both (Jenkins and Ricklefs 2011). This overlap is evident in the layout of Ecol- ogy of North America. With a scalable subject such as ecosystems, the authors could have ap- proached the discussion of their material from various angles. Their decision to employ a biome- structured theme to describe the assemblage of North American ecosystems is both logical and practical. This approach is certain to be appealing to biogeographers who use the textbook. In fact, this book could be used as a supplementary text- book in a biogeography class. Ecology of North America will serve as a good introductory text for students interested in the ecology of the continent. The book begins with an overview chapter of basic ecological prin- ciples and terms, including sound explanations of succession, biodiversity, and biogeography. Subse- quent chapters are individually devoted to various North American ecosystems/biomes. These chap- ters define the unique attributes of each biome and fluidly address the important abiotic and bio- tic components of each, along with representative plant and animal assemblages, interactions, and adaptations, as well as characteristic biome-level disturbances and ecological challenges. Both au- thors are wildlife ecology experts, yet their knowledge and understanding of plant ecology and their success in balancing the text between floral and faunal ecological discussions are both refreshing and impressive. The authors are careful and right to point out the major differences between biomes and ecosystems, but with a text that relies on a biome- structured outline, the omission of tropical sea- sonal forest and tropical rain forest biomes is marked. The authors admittedly target an audi- ence of “both undergraduate students and the general public” and aimed to write the text in a “user-friendly format.” Oftentimes, content must be edited and limited to achieve such goals, but these two major biomes that cover vast expanses of Mexico and Central America should be included in a comprehensive text of North American eco- systems. The inclusion of “infoboxes” is a meaningful addition; this type of aside succeeds in adding in- terest and depth to textbooks. Comprehensive bibliographies are included after each chapter, and the division of each one by chapter sub- headings is helpful. The chapters, however, could benefit from regional maps to remind students of the spatial distributions of each ecosystem, as well as brief, end-of-chapter summative and synthetic sections that include suggested questions for deeper thought. Such materials often help stu- dents see ‘big-picture’ applications of themes they have just read. Chapter 6, “Regional grasslands and related areas”, is a welcome expansion of the previous chapter on plains and prairies. I found myself wanting more of this type of expanded case-study approach for the other biomes ad- dressed in the text. Chapter 12, “A selection of special environments”, is a similarly assembled and written chapter; I found these chapters to be two of the most interesting and well written in the book. Chapter 11, “Coastal environments”, is new to this edition and introduces key information on arguably the most ecologically important collec- tion of environments in this age of globally warm- ing temperature and sea-level rise. Ecology is a dynamic field of study, and there are several comprehensive works that de- scribe biomes and ecosystems on varying scales. Readers wishing to explore an exhaustive explana- tion of North American biomes, but with little mention of faunal interactions, should read Bar- bour and Billings (2000). Others (e.g., Molles 2015; Cain et al. 2013) offer well-written, compre- hensive, and traditional ecology textbooks, but with a global focus that does not offer the same frontiers of biogeography 8.4, 2016 — © 2016 the authors; journal compilation © 2016 The International Biogeography Society

Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans.

Xenarthra (armadillos, sloths, and anteaters) constitutes one of the four major clades of placental mammals. Despite their phylogenetic distinctiveness in mammals, a reference phylogeny is still lacking for the 31 described species. Here we used Illumina shotgun sequencing to assemble 33 new complete mitochondrial genomes, establishing Xenarthra as the first major placental clade to be fully sequenced at the species level for mitogenomes. The resulting data set allowed the reconstruction of a robust phylogenetic framework and timescale that are consistent with previous studies conducted at the genus level using nuclear genes. Incorporating the full species diversity of extant xenarthrans points to a number of inconsistencies in xenarthran systematics and species definition. We propose to split armadillos into two distinct families Dasypodidae (dasypodines) and Chlamyphoridae (euphractines, chlamyphorines, and tolypeutines) to better reflect their ancient divergence, estimated around 42 Ma. Species delimitation within long-nosed armadillos (genus Dasypus) appeared more complex than anticipated, with the discovery of a divergent lineage in French Guiana. Diversification analyses showed Xenarthra to be an ancient clade with a constant diversification rate through time with a species turnover driven by high but constant extinction. We also detected a significant negative correlation between speciation rate and past temperature fluctuations with an increase in speciation rate corresponding to the general cooling observed during the last 15 My. Biogeographic reconstructions identified the tropical rainforest biome of Amazonia and the Guiana Shield as the cradle of xenarthran evolutionary history with subsequent dispersions into more open and dry habitats.

Relationships among phosphorus, molybdenum and free-living nitrogen fixation in tropical rain forests: results from observational and experimental analyses

Biological nitrogen (N) fixation is the primary source of “new” N to unmanaged ecosystems, and recent analyses suggest that terrestrial N inputs via free-living N fixation may be more important than previously assumed. This may be particularly true in some tropical rain forests, where free-living fixation could outpace symbiotic N fixation to represent the dominant source of new N inputs. However, our understanding of the controls over free-living N fixation in tropical rain forests remains poor, which directly constrains our ability to predict how N cycling will respond to changing environmental conditions. Although both phosphorus (P) and molybdenum (Mo) availability have been shown to limit free-living N fixation rates in the tropics, few studies have simultaneously explored P versus Mo limitation or the potential importance of P × Mo interactions. Here, an archived set of foliar, litter, and soil samples from a Costa Rican tropical rain forest provided an opportunity to simultaneously assess the relative strength of P versus Mo relationships with free-living N fixation rates. We also conducted a short-term, full-factorial (P × Mo) litter incubation experiment to directly assess nutrient limitation, allowing us to explore P and Mo controls over free-living N fixation rates using both observational and experimental approaches. We previously showed that N fixation rates were positively correlated with P concentrations in all substrates and, using the archived samples, we now show that Mo concentrations correlated with N fixation only in canopy leaves (where total Mo concentrations were extremely low). Likewise, fertilization with P alone (and not Mo) stimulated leaf litter N fixation rates. Thus, our results suggest that P availability dominantly controls free-living N fixation at this site, and when taken with data from other studies, our results suggest that attempts to identify “the nutrient” that limits N fixation in “the tropics” may be misguided. Rather, nutrient controls over free-living N fixation appear to be more nuanced—and the true nature of nutrient limitation to N fixation likely varies over a variety of scales across the vast tropical rain forest biome.

Tropical rain forest evolution: palms as a model group

The biological diversity and complexity of tropical rain forests have fascinated biologists for centuries. This, the most species-rich terrestrial biome on Earth, is now severely threatened by human activity and yet we are still far from answering fundamental questions about its origins and evolution. Where and how did this huge diversity originate? What evolutionary processes were involved? How can we explain the patterns of current biodiversity across this biome? Basic biodiversity data, such as species composition, distribution and phylogenetic relationships, are fundamental prerequisites for a better understanding of tropical rain forest evolution. Species inventories, for example, can be exploited to unpick the evolutionary history of tropical rain forest assemblages using community phylogenetic approaches [1]. Perpendicular to this approach, taxonomic and systematic research focusing on lineages predominantly restricted to tropical rain forests can be rewarding [2]. In particular, dated phylogenies of tropical rain forest lineages can be used to unravel the evolutionary origins, timescales and processes of this biome as a whole. In this comment, we describe how one such tropical rain forest-restricted lineage, the palm family, has provided evidence of global rain forest history in a succession of recent studies integrating a range of basic biodiversity datasets [3-9], the first of which was published in BMC Biology [3], and now represents a model for the study of the tropical rain forest biome that may, potentially, be applied to other lineages of organisms.

American-Australian Scientific Expedition to Arnhem Land (1948): Its Long-Range Impact

The American-Australian Scientific Expedition to Arnhem Land in the Northern Territory of Australia was sponsored by the National Geographic Society and the Smithsonian Institution in the United States and the Commonwealth Government of Australia. During 1948, two anthropologists, an archaeologist, four biological scientists and three health and nutrition experts, with two photographers and three support staff, spent eight months studying the ecology of this infertile, monsoonal landscape to learn how the present-day Aborigines who had arrived between 3500 and 5000 years ago displacing the first hunter-gatherers, the Mimi, who arrived some 53,000 to 60,000 years before were able to survive throughout the year. The Gondwanan origins of the heathy flora of the sandstones, the grassy eucalypt forests and woodlands on the lateritic earths, the monsoonal rainforests, the wetland and coastal plant communities -with vegetation structures similar to those in southern Australia inspired long-term research on the physico-chemical processes (aerodynamic, water relations and mineral nutrition) that determine the structure, growth and biodiversity of plant formations throughout Australia. The cooperative research that was fostered between the United States and Australia during the 1948 Arnhem Land Expedition has continued over the last sixty years in the Fulbright Program, the UNESCO Arid Zone Research Programme, the International Biological Programme (especially in the Arid Zone Biome, the Grassland Biome, the Mediterranean-climate Biome, the Heathland Biome, the Wet-Dry Tropical Biome and Rainforest Biome Programs), the International Union for the Conservation of Nature and, since the 1990s, the International Geosphere-Biosphere Programme to tackle Global Warming.

Evolutionary history of Dengue virus type 4: Insights into genotype phylodynamics

Dengue virus type 4 (DENV-4) circulates in tropical and subtropical countries from Asia and the Americas. Despite the importance of dengue virus distribution, little is known about the worldwide viral spread. Following a Bayesian phylogenetic approach we inferred the evolutionary history of 310 isolates sampled from 37 countries during the time period 1956–2008 and the spreading dynamics for genotypes I and II. The region (tropical rainforest biome) comprised by Malaysia–Thailand was the most likely ancestral area from which the serotype has originated and spread. Interestingly, cross-correlation analysis on demographic time series with the Asian sequences showed a statistically significant negative correlation that could be suggestive of competition among genotypes within the same serotype.

Land surface modeling inside the Biosphere 2 tropical rain forest biome

Tropical rain forests contribute substantially to regional and global energy, water, and carbon exchanges between the land surface and the atmosphere, and better understanding of the mechanisms of vegetation response to different environmental stresses is needed. The Biosphere 2 facility provides an opportunity to link laboratory‐scale and plot‐scale studies in a controllable environment. We compiled a consistent quality‐controlled time series of climate data from Biosphere 2 and used it to drive the Simple Biosphere model (SiB3) to test how well it represented the behavior of soils and vegetation inside the tropical rain forest biome of Biosphere 2 (B2‐TRF). We found that soil respiration parameterization in SiB3 was not suitable for use in B2‐TRF, so several alternative parameterizations were tested. None gave outstanding results, but a modified version of the parameterization originally proposed for SiB3 gave the best results. With this modification, SiB3 well simulated the observed net ecosystem exchange in B2‐TRF but, significantly, only after additionally modifying parameters describing the thermal tolerance of plants so that photosynthetic capacity was reduced on average but maintained to higher temperatures. This implies either that tropical rain forest species can acclimate to higher temperatures than allowed for by vegetation models or that the plant community assembly in B2‐TRF has shifted to allow continued functioning at higher temperatures, and plants in natural ecosystems could also. In either case, this suggests that the Amazon rain forest may be more resilient to climate change than hitherto thought.