Tropical Rain Forests In Africa Research Articles

Monkeypox: An international epidemic.

Human monkeypox (MPX) is a viral zoonosis caused by the Monkeypox virus. For decades outbreaks exclusively occurred in the tropical rainforests of Africa, with a few imported cases and very limited human-to-human transmission outside Africa. Nevertheless, in the last years sustained outbreaks have emerged, peaking at 4600 cases in 2020 in the Democratic Republic of Congo. Since May 2022, an international epidemic originated at 2 events in Spain and Belgium led to sustained human-to-human transmission across multiple continents, mostly in males having sex with males subjects. We review here clinical presentation, epidemiology, viral evolution, vaccines, and therapeutics against human MPX.

Analysis of Rainfall Infiltration Stability of High Liquid Limit Red Clay Roadbed in Africa.

The annual rainfall in tropical rain forests in Africa is concentrated, and the abundant rainfall can easily lead to roadbed landslides. Therefore, it is necessary to analyze the impact of rainfall on the stability of roadbeds. This paper first uses the pore fluid permeability/stress coupling analysis step provided by ABAQUS to calculate the impact of rainfall infiltration on the overall stability of the roadbed slope and then discusses the rainfall infiltration on the slope seepage field, stress field, and displacement combined with the strength reduction method and the influence of field and safety factors. In the end, it is concluded that the 72-hour rainfall with an intensity of 50 mm/d will reduce the safety factor of the roadbed by 4.9% compared with before the rainfall. At the same time, it will increase the internal pore water pressure of the roadbed, reduce the suction of the matrix, and reduce the effective stress, which is caused by various factors. The overall stability of the roadbed is reduced.

Late Maastrichtian vegetation and palaeoclimate: Palynological inferences from the Deccan Volcanic Province of India

Our understanding of the low latitude terrestrial climate of the late Maastrichtian is far from satisfactory. We have attempted to reconstruct the late Maastrichtian vegetation and climate of the Deccan Volcanic Province (DVP), central India. Palaeomagnetic results suggest that the Deccan lava flows were emplaced during the late Maastrichtian C29r magnetochron. Sedimentological studies reveal a swampy to shallow brackish lacustrine depositional setup in a warm and humid climate with low to moderate energy conditions. The floristic composition indicates an overall dominance of Arecaceae followed by Malvaceae and Ephedraceae. The vegetation prevailed under five palaeoecological associations viz., mangrove, coastal fringes, Tropical Rain Forests (TRFs), forest outliers and upland flora. The assemblage envelops taxa belonging to TRFs (54%), coastal (13%), tropical moist deciduous (13%), herbaceous (8%), mangrove (8%), and sub-tropical (4%) vegetation. The TRFs include taxa presently prevailing within the Western Ghats of India and in the TRFs of Africa. The Coexistence Approach (CA) analysis suggests a mean annual temperature of 24.5 ± 2.3 °C, cold month mean temperature of 18.5 ± 3.3 °C, warm month mean temperature of 27.5 ± 0.3 °C, mean annual precipitation of 1890.5 ± 208.5, precipitation during the wettest month 335 ± 15 mm, precipitation during the driest month 26 ± 7 and precipitation during the warmest month 111 ± 1. The inferred climatic conditions were apt for sustaining the high diversity within the close canopy multi-storeyed TRFs. The palaeoclimatic data also indicates a strong seasonality, and most likely, a monsoon type of climate during the late Maastrichtian of India.

Possible semi-circumglobal teleconnection across Eurasia driven by deep convection over the Sahel

The Sahel region, located between the tropical rainforests of Africa and the Sahara Desert, has rainfall that varies widely from year to year, associated with extremely deep convection. This deep convection, strongly heated by water vapor condensation, suggests the possibility of exerting a remote influence on mid- and high-latitude climate similar to the well-known influences of tropical oceanic convection on global climate. Here we investigate the possibility that deep convection over the Sahel initiates a semi-circumglobal teleconnection extending to eastern Eurasia. Statistical analysis and numerical experiments support the possible existence of this teleconnection at an interannual time scale. We propose that the anomalous heat source due to deep convection over the Sahel in the late monsoon season influences meandering of the mid-latitude jet stream over Europe through the combination of a Matsuno-Gill response and advection of absolute vorticity. This subtropical jet meander may in turn drive an eastward propagation of a Rossby wave across Eurasia as far as East Asia. Because deep convection over other subtropical land areas may exert a similar remote influence upon extratropical extreme weather, further studies of the influence of overland convection may provide us with an expanded comprehension of teleconnections.

Phylogeny and taxonomic revision of the genus Craterispermum (Rubiaceae) in the Seychelles Archipelago

The genus Craterispermum (Craterispermeae, Rubiaceae) is distributed in the tropical rain forests of Africa and Madagascar, with one morphologically variable species (Craterispermum microdon) hitherto recognized in the Seychelles Archipelago. We conducted a Bayesian analysis of the combined ETS and ITS sequence data to: 1) test the monophyly of the Seychellois species of Craterispermum; and 2) assess the phylogenetic relationships between the island populations. Our analyses supported the monophyly and, therefore, the single Malagasy origin of the Seychellois Craterispermum. The phylogenetic relationships between the three island populations were unresolved, since the Seychellois plants display a very low level of molecular variation. However, both herbarium and field studies revealed that the Craterispermum taxa occurring on the islands of Mahe, Praslin, and Silhouette, are morphologically distinct and geographically separated. As a result of these studies, two new species, Craterispermum praslinense and C. silhouettense, are described, to accommodate the Praslin and Silhouette populations, respectively, and C. microdon is restricted to the population on Mahe Island. A new taxonomic account for the Seychellois Craterispermum, and an identification key to the three species present in the archipelago, are provided. A provisional conservation status of each species, according to the IUCN Categories and Criteria, is presented.

Climate at ecologically relevant scales: A new temperature and soil moisture logger for long-term microclimate measurement

Climate measurements are needed at a scale at which organisms live and die. Currently available climate sensors, however, are not well suited for long-term field measurements at such a scale. We have therefore developed a new temperature and moisture logger, the Temperature-Moisture-Sensor (TMS), which we designed for a wide range of ecological applications. The device mimics a small herbaceous plant. Its belowground part houses a patented, proprietary soil moisture sensor working on the time-domain transmission principle. Air, surface and soil temperatures are measured simultaneously by three independent sensors. The TMS data logger has a large memory and long battery life, so it is suitable for taking long-term microclimate measurements in the field. With a data acquisition interval of 15 min, it has sufficient memory to last for almost 15 years.We have thoroughly tested the TMS logger both in the laboratory and in demanding field conditions ranging from tropical rain forests of Africa to high-elevation cold deserts of the Himalayas. The device has provided microclimate measurements in a wide range of environmental conditions and has also performed well in controlled laboratory settings.The key added value of the TMS logger is that it concurrently measures soil moisture as well as soil, surface and air temperature at a biologically relevant scale. It is also able to continuously measure the microclimate for several years even in the most extreme conditions. The device can therefore be used to build extensive tailored field measurement networks providing crucial data about microclimate conditions shaping biological processes in the face of climate change.

Acute blindness as a presenting sign of childhood endemic Burkitt\u2019s lymphoma in Cameroon: a case report

BackgroundEndemic Burkitt’s lymphoma is found predominantly in malaria holoendemic zones, typically in the tropical rain forest of Africa. It usually presents as an extra-nodal tumour in children and young adults with predilection for jaws and soft tissues of the abdomen. Clinical features depend on the primary tumour site, extent of the disease and histologic subtype. Acute blindness as a presentation sign is rare.Case presentationA 13 year old African female presented to our facility with a 3 week history of painful abdominal distention, and loss of vision of the left eye. On examination, there was a huge abdominopelvic mass, left breast mass and complete blindness of the left eye associated with mydriatic pupils non-responsive to light. An abdominal ultrasound showed a huge hypoechoic mass arising from the pelvis and protruding into the abdomen. The jaws, teeth and maxilla were all normal. A fine needle aspiration done was negative for malignant cells. A presumptive diagnosis of Burkitt’s lymphoma was made on clinical grounds and abdominal ultrasound findings. The patient was immediately placed on chemotherapy and responded well to treatment with remission of the tumour but persistence of left eye blindness.ConclusionAcute blindness can be the presenting sign of Burkitt’s lymphoma in a patient with neither jaw nor maxillary swelling. Primary healthcare providers in low income settings require a high index of suspicion when faced with such atypical presentations. This emphasizes the need for thorough physical examination, and when possible, the clinical utility of ultrasonography for suspicious abdominal masses in the absence of state-of the art diagnostic tools for early diagnosis and treatment, which is critical for survival and to improve quality of life.

DESTRUCTION OF FOREST AREAS AS A RESULT OF LOGGING AND HARVESTING IN AFRICAN OR AMERICAN DENSE TROPICAL RAINFORESTS

Il est devenu habituel de lire dans les médias des articles accusant l’exploitation fores- tière d’être le moteur principal de la dispari- tion des forêts tropicales. Ce raccourci trom- peur est imputable à une méconnaissance des réalités forestières, d’une part, et à un amalgame entre l’exploitation forestière et le défrichement agricole, d’autre part. L’ob- jet de cet article rédigé par un praticien fami- lier du contexte forestier tropical était d’éva- luer l’impact de l’exploitation forestière sur les forêts denses tropicales humides, dans les deux continents africain et améri- cain. Par souci d’exactitude, les phases de l’exploitation ont été distinguées : installa- tion de la base vie, constitution du réseau routier de vidange des bois, réalisation des opérations d’exploitation proprement dites. Des scénarios ont été distingués en fonction de la richesse de la forêt, dont le volume ré- colté varie de 3 à 15 m3/ha. Ces estimations confirment que la destruction du couvert fo- restier demeure si faible qu’à l’exception de situations radicales l’exploitation forestière ne constitue pas une menace pour le main- tien durable des forêts tropicales. La mise en place des réseaux routiers et de pistes de débardage affecte de 4,5 à 5,5 % du couvert forestier. Les surfaces des trouées consé- cutives à l’abattage ne dépassent jamais 4 % du couvert, et restent inférieures à 2 % pour les forêts riches ou de richesse moyenne. L’exploitation forestière n’est donc direc- tement responsable que de la destruction de 5,5 à 8,5 % du couvert forestier. Dans le cas de forêts riches, des exploitations fores- tières successives peuvent certes atteindre 12 à 16 % du couvert forestier. Mais c’est alors sans compter sur la dynamique de reconstitution de la biomasse opérant natu- rellement entre deux séquences d’exploi- tation. En Asie du Sud-Est où l’exploitation est plus intensive en raison d’un potentiel commercial très élevé, la reconstitution du couvert est acquise en 20 ans. Si la valeur économique d’une forêt dense tropicale humide diminue avec l’exploitation, ses va- leurs biologique et écologique restent quant à elles sensiblement intactes.

Taxonomic revision of the African genera Brieya and Piptostigma (Annonaceae)

Background and aims – Annonaceae are an important family in tropical rain forests of Africa. Here, we present a revision of the west-central African genus Piptostigma of the tribe Piptostigmateae. Previous molecular phylogenetic analyses of Piptostigmateae have revealed that the genus as currently circumscribed is paraphyletic. The aims of the article are: (1) to clarify the generic delimitation of the genus Piptostigma, especially in relation to its current polyphyletic delimitation; (2) to provide a new updated key to the genera of tribe Piptostigmateae; and (3) to provide for the first time in over 100 years a complete taxonomic revision of genera Brieya and Piptostigma. Material and methods – Normal practices of herbarium taxonomy were used for the morphological study of about 200 specimens from B, BR, BRLU, G, HBG, K, L, LBV, LISC, MO, P, U, US, WAG, YA and Z. We sequenced three plastid regions for 32 samples representing 26 ingroup (Piptostigmateae) and six outgroup species in order to explore the paraphyly of Piptostisma. The open source software QGis was used to generate the distribution maps of the species and their conservation status was obtained using the IUCN categories and criteria.Key results – Molecular and morphological evidence support the reinstatement of the genus Brieya De Wild. Three keys are presented, one to the genera of Piptostigmateae and the two others to the species of Brieya and Piptostigma. A total of thirteen species are described for Piptostigma and two for the genus Brieya. Four new species are presented for the genus Piptostigma: P. macrophyllum, P. mayndongtsaeanum, P. goslineanum and P. submontanum.

Restoring tropical rain forests: Policies to protect tropical rain forests and efficient restoration measures require research-based evidence on biodiversity and ecology.

Tropical rain forests have suffered badly for many decades owing to human exploitation and deforestation and, more recently, climate change. The rapid decline in rainforests that are teeming with life has had scientists and environmentalists worrying not only about the loss of biodiversity, but also about how the disappearance of huge areas of forests will impact on regional and global climate. After nearly a century of destruction, tropical rain forests in Africa and South America have now reached a critical point at which they could either disappear altogether or slowly recover. However, there are signs that the rate of decline can at least be halted and even reversed. The future depends not just on government actions and inhabitants, but also further research on these delicately balanced ecosystems: Recent studies have suggested that a global temperature rise of 4°C would represent an irreversible tipping point for rain forests beyond which there would be no return [1]. At least such warnings have been headed by some governments, most notably in Brazil, which has achieved a dramatic decline in deforestation rates during the past 13 years after 50 years of rapid loss. At the peak of deforestation in 2004, 27,400 square kilometers of Amazon rainforest was cleared per year, while 2014 forest clearance had decreased to around 5,000 square kilometers, according to Brazilian government figures (http://www.obt.inpe.br/prodes/index.php). ### Protect and replant Yet, there is no cause for complacency. Most of that decline in deforestation has been attributed to Brazil and has not been matched in most other countries. Furthermore, there have been signs that the decline in deforestation in the Amazon area is bottoming out, partly reflecting the fact that Brazil's efforts have targeted large clearances of 500 hectares or more while current deforestation is occurring chiefly in smaller plots. A recent study confirmed that …

BoHV-4-Based Vector Single Heterologous Antigen Delivery Protects STAT1(-/-) Mice from Monkeypoxvirus Lethal Challenge.

Monkeypox virus (MPXV) is the etiological agent of human (MPX). It is an emerging orthopoxvirus zoonosis in the tropical rain forest of Africa and is endemic in the Congo-basin and sporadic in West Africa; it remains a tropical neglected disease of persons in impoverished rural areas. Interaction of the human population with wildlife increases human infection with MPX virus (MPXV), and infection from human to human is possible. Smallpox vaccination provides good cross-protection against MPX; however, the vaccination campaign ended in Africa in 1980, meaning that a large proportion of the population is currently unprotected against MPXV infection. Disease control hinges on deterring zoonotic exposure to the virus and, barring that, interrupting person-to-person spread. However, there are no FDA-approved therapies against MPX, and current vaccines are limited due to safety concerns. For this reason, new studies on pathogenesis, prophylaxis and therapeutics are still of great interest, not only for the scientific community but also for the governments concerned that MPXV could be used as a bioterror agent. In the present study, a new vaccination strategy approach based on three recombinant bovine herpesvirus 4 (BoHV-4) vectors, each expressing different MPXV glycoproteins, A29L, M1R and B6R were investigated in terms of protection from a lethal MPXV challenge in STAT1 knockout mice. BoHV-4-A-CMV-A29LgD106ΔTK, BoHV-4-A-EF1α-M1RgD106ΔTK and BoHV-4-A-EF1α-B6RgD106ΔTK were successfully constructed by recombineering, and their capacity to express their transgene was demonstrated. A small challenge study was performed, and all three recombinant BoHV-4 appeared safe (no weight-loss or obvious adverse events) following intraperitoneal administration. Further, BoHV-4-A-EF1α-M1RgD106ΔTK alone or in combination with BoHV-4-A-CMV-A29LgD106ΔTK and BoHV-4-A-EF1α-B6RgD106ΔTK, was shown to be able to protect, 100% alone and 80% in combination, STAT1(-/-) mice against mortality and morbidity. This work demonstrated the efficacy of BoHV-4 based vectors and the use of BoHV-4 as a vaccine-vector platform.

Attribution of changes in precipitation patterns in African rainforests

Tropical rainforests in Africa are one of the most under-researched regions in the world, but research in the Amazonian rainforest suggests potential vulnerability to climate change. Using the large ensemble of Atmosphere-only general circulation model (AGCM) simulations within the weather@home project, statistics of precipitation in the dry season of the Congo Basin rainforest are analysed. By validating the model simulation against observations, we could identify a good model performance for the June, July, August (JJA) dry season, but this result does need to be taken with caution as observed data are of poor quality. Additional validation methods have been used to investigate the applicability of probabilistic event attribution analysis from large model ensembles to a tropical region, in this case the Congo Basin. These methods corroborate the confidence in the model, leading us to believe the attribution result to be robust. That is, that there are no significant changes in the risk of low precipitation extremes during this dry season (JJA) precipitation in the Congo Basin. Results for the December, January, February dry season are less clear. The study highlights that attribution analysis has the potential to provide valuable scientific evidence of recent or anticipated climatological changes, especially in regions with sparse observational data and unclear projections of future changes. However, the strong influence of sea surface temperature teleconnection patterns on tropical precipitation provides more challenges in the set up of attribution studies than midlatitude rainfall.

Wood density, phytomass variations within and among trees, and allometric equations in a tropical rainforest of Africa

The development of tree allometric equations is crucial to accurate forest carbon assessment. However, very few allometric equations exist for sub-Saharan Africa and as a result generalized allometric equations, often established for forests in other continents, are used by default. The objectives of this study were (1) to propose a sampling methodology and calculation procedures to assess biomass for tropical tree species of contrasted tree shapes in Africa, (2) to identify factors affecting within and between trees wood density, (3) to propose an allometric model that integrates these factors and (4) to evaluate the reliability of using generalized allometric equations in this type of forests. Models were developed to predict wood density and phytomass of the trees based on the harvesting of 42 trees from 16 species, representing three guild status in the wet evergreen forest of Boi Tano in Ghana. Results indicated that the wood density was highly influenced by the tree species, guild status, size of the tree and pith to bark distance. Dry mass of a tree was influenced by diameter at breast height, crown diameter and wood density. The wood density depends on the position of the wood within the tree and the guild status considered. The use of generalized allometric models in literature is limited by the specific climate zone, the consideration of tree height and species specific wood density. In considering those factors, using generalized allometric equations could result in an error of 3%. Further research should better consider the bigger trees and the influence of the topography and ecosystem history.

Severe declines of ant-following birds in African rainforest fragments are facilitated by a subtle change in army ant communities

Tropical rainforests are disappearing at a rapid rate. Although several studies have revealed the detrimental effects of forest fragmentation on tropical birds, the ecological mechanisms facilitating the decline of populations have been poorly documented. In the tropical rainforests of Africa and America, ant-following birds track the massive swarm raids of army ants and prey on animals which are flushed by the ants. We analyzed the persistence of five species of ant-following birds along a habitat fragmentation gradient in western Kenya and tested if bird populations are limited by the abundance of army ant colonies in forests. Abundances of four of five ant-followers declined by 52–100% in forest fragments ⩽113 ha. Multi-model Bayesian inference suggests that the decline of the three most specialized ant-followers is facilitated by a decrease in the abundance of the army ant Dorylus wilverthi in small forest fragments. Our data suggests that a second, fragmentation-tolerant army ant species, Dorylus molestus, does not functionally compensate for the decline of D. wilverthi because, first, of a higher affinity of birds to D. wilverthi raids (found for one species). Second, because the daytime activity of D. molestus is dependent on high humidity conditions, a pattern which was not found for D. wilverthi. Consequently, specialized ant-followers in small fragments, where D. wilverthi is missing, probably suffer from food scarcity due to a cease of army ant foraging in the dry season. Our results suggest that a subtle alteration of army ant communities caused by habitat fragmentation may have large ecological consequences.

Sensitivity of MOPITT observations to carbon monoxide in the lower troposphere

The sensitivity of Measurements of Pollution in the Troposphere (MOPITT) observations to carbon monoxide (CO) concentrations in the lower troposphere (LT) varies widely as the result of variability in thermal contrast conditions. This effect is evident in both the MOPITT weighting functions and averaging kernels, particularly after these quantities are properly normalized to remove grid effects. Comparisons of simulated weighting functions and averaging kernels with operational data confirm the significance of thermal contrast effects. Retrieval sensitivity to LT CO is greatest in daytime observations over land, particularly in tropical and midlatitude regions exhibiting large diurnal variations in surface temperature. Nighttime observations over land typically exhibit poor sensitivity to LT CO. On the global scale, analysis of MOPITT averaging kernels for 1 month indicates that daytime MOPITT observations offer useful sensitivity to LT CO over large areas of most continents. Exceptions include tropical rainforests in Africa and South America, where thermal contrast conditions are relatively weak.

Genetic diversity of ectomycorrhizal Basidiomycetes from African and Indian tropical rain forests

Ectomycorrhizal (ECM) fungi have a worldwide distribution. However, the ecology of tropical ECM fungi is poorly documented, limiting our understanding of the symbiotic associations between tropical plants and fungi. ECM Basidiomycete diversity was investigated for the first time in two tropical rain forests in Africa (Western Upper Guinea) and in Asia (Western Ghats, India), using a fragment of the mitochondrial large subunit rRNA gene to type 140 sporocarps and 54 ectomycorrhizas. To evaluate taxonomic diversity, phylogenetic analyses were performed, and 40 sequences included from identified European specimens were used as taxonomic benchmarks. Five clades were recovered corresponding to six taxonomic groups: boletoids, sclerodermatoids, russuloids, thelephoroids, and a clade grouping the Amanitaceae and Tricholomataceae families. Our results revealed that the Russulaceae species display a great diversity with several putative new species, especially in Guinea. Other taxonomic issues at family/section levels are also briefly discussed. This study provides preliminary insights into taxonomic diversity, ECM status, and biogeographic patterns of ECM fungi in tropical two rain forest ecosystems, which appear to be as diverse as in temperate and boreal forests.

A GCM study of climate change induced by deforestation in Africa

In this modeling study we investigated the potential climate change which would result from totally clearing the tropical rain forests in Africa. The primary research vehicle in our investigation was the standard version of the National Center for Atmospheric Research (NCAR) CCM3 global climate model (GCM), with a horizontal resolution of triangular spectral truncation T42 (approximately 2.8° × 2.8°). Two separate 10 yr simulations were performed; for each of these the global climatological sea surface temperature field was prescribed. The purpose of the 10 yr simulations was to provide a sufficiently large ensemble whose average minimizes model noise errors. In the control simulation normal vegetation was prescribed. The design of the anomaly experiment was similar to the control run except that the tropical rainforest regions in Africa were replaced by savanna grassland vegetation. The CCM3 GCM successfully simulated the primary features of the seasonal mean climate conditions over Africa. The model results show that replacement of tropical rain forest vegetation with savanna grassland vegetation produces the following climate changes over Africa: (1) Over the deforested region, the model results indicate a significant reduction in areaaveraged rainfall throughout the year. The decrease ranges between 2 to 3 mm d–1 during the northern hemispheric summer months, when the region experiences the driest conditions (July to September), and less than 1 mm d–1 during the wettest months (autumn and spring). (2) Over southern Africa deforestation results in substantial rainfall reduction over Mozambique and rainfall increase over Botswana, Zambia, the southern region of the Democratic Republic of the Congo, and parts of South Africa. Changes in the trapped Rossby wave train activity generated by the mid-tropospheric latent heating over the tropical forest region are responsible for the continental-scale teleconnection climate response. (3) Over Eastern and Western Africa the impact of deforestation is primarily characterized by a reduction in rainfall, however the adopted GCM T42 resolution may not have been adequate to resolve the large contrasts in terrain and vegetation types. (4) Over the rest of Africa the response is relatively weak.

Monkeypoxvirus infections.

During and after the smallpox eradication campaign, human cases of monkeypox appeared in West and Central Africa, as isolated cases or as small epidemics. Since inter-human transmission has never or only very exceptionally been documented, monkeypox does not represent a serious threat to humans. The virus reservoir is among tree squirrels living in the tropical rain forests of Africa and humans are infected by hunting, killing and skinning these animals. However, the modernization of society lessens human contact with the virus reservoir. Since the eradication of smallpox, stocks of variola virus have been maintained; whether these stocks should now be destroyed is a political question, which is seriously compromised by mistrust between countries.

Ecology of an African rain forest: logging in Kibale and the conflict between conservation and exploitation

Thomas T. Struhsaker summarizes 20 years of research in the Kibale forest in Uganda, one of the most important centers for the study of tropical rain forests in Africa. Among the longest ongoing projects in rain forest ecology anywhere, Struhsaker's differs from the great majority of logging studies by emphasizing the fauna rather than looking only at the commercially valuable timber species. By providing long-term data on a variety of plants and animals, it offers the first truly in-depth synthesis of the consequences of selective logging in the tropics. The main body of the book demonstrates the adverse effects of logging - as many as 25 years after the event - on community structure and numerous other aspects of forest ecology. The long-term data summarized here on the population dynamics of rain forest trees, primates, rodents, duikers, and elephants are unrivaled and will be widely cited, as will the data on seasonality, tree phrenology, gap dynamics, rainfall, and temperature. Struhsaker addresses the underlying causes of tropical deforestation and concludes that although there are numerous proximate factors, the ultimate causes are rapidly increasing human populations and rates of consumption per capita. He draws comparisons with relevant studies elsewhere in the tropics and offerse specific recommendations to address the problems.

Supervillage Formation in the Amazonian Terra Firme: The Case of Asenona

The relatively small size of settlements in the terra firme2 zone of the South American tropical forest has been the subject of much study and debate (see, for example, Steward & Faron 1959; Meggers 1957, 1971; Carneiro 1960, 1961; Lathrap 1968; Leeds 1969; Gross 1975, 1983; and Roosevelt 1980). In general, the size of settlements (as well as settlement mobility and location) in the terra firme has been viewed as an adaptation to the natural environment (see Hames 1983:393-405 for a succinct review of influencing factors). Regardless of the factors considered by researchers, the primary focus of investigation has been to explain why settlements are small, generally having 50 to 150 inhabitants (Steward 1949:676, Map 19), and why settlements are moved frequently (for example, every five to twenty years) (Gross 1983:429). The limiting influences of the world's tropical rain forest environments on cultural development have also received considerable attention from researchers who now recognize that the tropical rain forest biome is not a homogeneous entity and that significant variation in its natural environmental potential is present (see Parker et al. 1983, for Amazonia). Large settlements (even cities in some locales) existed in the tropical rain forests of Africa, Southeast Asia, Mesoamerica, and South America in the precolonial period. Therefore, the limitations imposed by the tropical rain forest environment on human population concentrations have been overcome in many instances. However, even when compared to other tropical rain forest zones, the Amazonian terra firme is still regarded as exceptionally resource-poor (Meggers 1971; Sponsel 1986). This view is based partially upon ecological research in terra firme areas that has shown them to be relatively less rich in natural resources than other tropical rain forest environments. Moreover, since ethnographic data for the precolonial period are lacking, the relative scarcity of resources in the terra firme has been inferred from ethnographic analogy. Researchers have tended to accept the proposition that the precolonial situation of human societies in the terra firme was similar to that encountered among extant, relatively unacculturated, groups. Since these groups live in small, impermanent settlements with seemingly simple sociopolitical systems, it is believed that this has always been the case in the area (Roosevelt 1989:30-34). Thus, the circular reasoning is that because humans in the area have not developed larger settlements and more complex sociocultural systems, the natural environment of the terra firme must be too limited in natural resources to permit such development. The ethnocentric and evolutionary bias of such a proposition must be recognized. It is based upon the idea that humans are naturally progressive. Progress, in this case, is toward permanent and large population settlements and more complex sociocultural systems. Although much valuable ecological