Liana Forest Research Articles

Unraveling pre-Columbian occupation patterns in the tropical forests of French Guiana using an anthracological approach

In Amazonia, a growing body of studies has shown that rainforests were affected by human occupation in many areas during pre-Columbian times, inducing changes in their floristic compositions. The northern part of Amazonia, and in particular the Guiana Shield, is much less studied, although past human occupations have also been documented in this region. Therefore, the actual impact of pre-Columbian societies on Guianan forests is still poorly known. Here we explore 12 sites in the dense forest of Nouragues, central French Guiana, ranging from a priori non-anthropogenic to clearly anthropogenic, using an anthracological approach. Soil charcoals were radiocarbon dated to assess the chronology of the past human occupations, and identified to determine shifts in vegetation cover. Our results show that two main periods of occupation can be distinguished on several sites in the Nouragues area: a first one between ca. 1,300 and 1,000 cal bp and a second one between ca. 600 and 400 cal bp. Charcoal identification reveals the presence of a secondary vegetation during this most recent period of occupation, as shown by the presence of pioneer and heliophilic taxa, suggesting that human activities induced and favored this kind of vegetation. The presence of valuable wood and edible species in the anthracological record could reflect selective exploitation of the former around dwelling areas and a concentration of the latter within anthropogenic sites. As shown by our anthracological results, all the sites which contained charcoal were once under forest cover, including those that are now covered by pseudo-bamboos or by liana forests. We therefore suggest that the type of human activity (e.g. dwelling or food production) may have had different impacts on the structure and composition of subsequent vegetation resulting either in anthropogenic forests or liana and pseudo-bamboo patches after land abandonment.

Habitat, species richness and hantaviruses of sigmodontine rodents within the Interior Atlantic Forest, Paraguay.

Four of the nine sigmodontine tribes have species that serve as reservoirs of rodent-borne hantaviruses (RBO-HV), few have been studied in any depth. Several viruses have been associated with human cases of hantavirus pulmonary syndrome often through peridomestic exposure. Jabora (JABV) and Juquitiba (JUQV), harbored by Akodon montensis and Oligoryzomys nigripes, respectively, are endemic and sympatric in the Reserva Natural de Bosque Mbaracayú (RNBM), Paraguay, a protected area of the Interior Atlantic Forest. Rodent communities were surveyed along a 30 km stretch of the RNBM in eight vegetation classifications (Low, High, Bamboo, Riparian and Liana Forests, Bamboo Understory, Cerrado, and Meadow/Grasslands). We collected 417 rodents from which 11 species were identified; Akodon montensis was the predominant species (72%; 95%CI: 64.7%-76.3%), followed by Hylaeamys megacephalus (15% (11.2%-18.2%)) and Oligoryzomys nigripes (9% (6.6%-12.4%)). We examined the statistical associations among habitat (vegetation class) type, rodent species diversity, population structure (age, sex, and weight), and prevalence of RBO-HV antibody and/or viral RNA (Ab/RNA) or characteristic Leishmania tail lesions. Ab/RNA positive rodents were not observed in Cerrado and Low Forest. A. montensis had an overall Ab/RNA prevalence of 7.7% (4.9%-11.3%) and O. nigripes had an overall prevalence of 8.6% (1.8%-23.1%). For A. montensis, the odds of being Ab/RNA positive in High Forest was 3.73 times of the other habitats combined. There was no significant difference among age classes in the proportion of Ab/RNA positive rodents overall (p = 0.66), however, all 11 RNA-positive individuals were adult. Sex and habitat had independent prognostic value for hantaviral Ab/RNA in the study population; age, presence of tail scar/lesion (19% of the rodents) and weight did not. Adjusting for habitat, female rodents had less risk of becoming infected. Importantly, these data suggest habitat preferences of two sympatric rodent reservoirs for two endemic hantaviruses and the importance of including habitat in models of species diversity and habitat fragmentation.

Two new species of Eugenia sect. Phyllocalyx (Myrtaceae) from Brazil

Summary. Two new endangered Brazilian species of Eugenia are described and illustrated, E. magnisepala and E. salacifolia. Eugenia magnisepala, collected in Matas de Cipo (liana forests) in the northeastern state of Bahia, is recognisable by its larger calyx lobes, membranaceous blades and costate ovary, traits not shared with the morphologically similar species E. itacarensis, E. involucrata, E. macrobracteolata and E. regia. Eugenia salacifolia was collected in seasonal Atlantic forests of the state of Minas Gerais and is similar to E. macrantha, from which it can be distinguished by its auxotelic inflorescences and larger and persistent bracteoles and calyx lobes.

A new endangered species of Psidium (Myrtaceae, Myrteae) from Bahia, Brazil

This paper describes a new, very distinctive, endangered species of Psidium (Myrtaceae, Myrteae) occurring in Bahia in Northeastern Brazil, in the Diamantina Atlantic Forest center of endemism, considered in the Atlantic Forest domain although transitional with the Caatinga domain. It is a small tree up to 5m tall. The species, that we have named Psidium rotundidiscum, is promptly recognized by the combination of petioles 4–7mm long, young leaves that are densely ferrugineous pubescent, spathulate and strongly revolute and mature leaves that are glabrescent, revolute, with an inconspicuous venation. The inflorescences are terminal precocious (auxotelic) racemes with 1–2 pairs of flowers or solitary flowers on new growth. Floral buds are nearly closed, ca. 7–10mm long and densely ferruginous pubescent; specimens with open flowers are unknown. The oblate fruits, with a rounded disk with relatively few staminal scars and rather thick, explanate calyx lobes are also distinctive. The species is known from only three late 20th/early 21st century collections from deciduous forests, semi-deciduous forests, liana forests and xerophytic forests along a North to South extension of ca. 700 km in inland Bahia. Images of collections in bud and in fruit are furnished as well as a geographic distribution map.

An assessment of the floristic composition, structure and possible origin of a liana forest in the Guayana Shield

Liana is a life form that possesses high importance in many Neotropical forests. Density of climbers apparently increases with the intervention rate (e.g. logging). The aim of this work is to characterize the structure, floristic composition and soils of a sector classified as Liana Forest (LF). We identified an LF sector in a not-logged area; three 1 ha square plots were measured (individuals ≥ 10 cm dbh, “diameter at breast height”). In each plot, we evaluate four 100 m2 square understory subplots (all spermatophyta individuals < 10 cm dbh). LF has a low canopy ( < 15 m) and is dominated by Alexa imperatricis and Pentaclethra macroloba. Basal area (20.4 m2ha− 1) and diversity (H′ = 2.6) are lower than other surrounding plots. Understory is dominated by gnarled climbers, and the most important are Cheiloclinium hippocrateoides and Bauhinia scala-simiae. Soil is extremely acidic, with very low fertility but is similar to neighboring places. We conclude that LF was neither originated by edaphic restrictions nor logging; LF probably suffered a hurricane wind that fell down most of the canopy trees, thick individuals of climber species also disappeared, and the current successional stage favors a recovery dominated with thin individuals of this life form.

Land-cover classification in a moist tropical region of Brazil with Landsat Thematic Mapper imagery

This research aims to improve land-cover classification accuracy in a moist tropical region in Brazil by examining the use of different remote-sensing-derived variables and classification algorithms. Different scenarios based on Landsat Thematic Mapper (TM) spectral data and derived vegetation indices and textural images and different classification algorithms, maximum likelihood classification (MLC), artificial neural network (ANN), classification tree analysis (CTA) and object-based classification (OBC), were explored. The results indicate that a combination of vegetation indices as extra bands into Landsat TM multi-spectral bands did not improve the overall classification performance, but the combination of textural images was valuable for improving vegetation classification accuracy. In particular, the combination of both vegetation indices and textural images into TM multi-spectral bands improved the overall classification accuracy (OCA) by 5.6% and the overall kappa coefficient (OKC) by 6.25%. Comparison of the different classification algorithms indicated that CTA and ANN have poor classification performance in this research, but OBC improved primary forest and pasture classification accuracies. This research indicates that use of textural images or use of OBC are especially valuable for improving the vegetation classes such as upland and liana forest classes that have complex stand structures and large patch sizes.

Pollen-based differentiation of Amazonian rainforest communities and implications for lowland palaeoecology in tropical South America

An ongoing controversy in Amazonian palaeoecology is the manner in which Amazonian rainforest communities have responded to environmental change over the last glacial–interglacial cycle. Much of this controversy results from an inability to identify the floristic heterogeneity exhibited by rainforest communities within fossil pollen records. We apply multivariate (Principal Components Analysis) and classification (Unweighted Pair Group with Arithmetic Mean Agglomerative Classification) techniques to floral-biometric, modern pollen trap and lake sediment pollen data situated within different rainforest communities in the tropical lowlands of Amazonian Bolivia. Modern pollen rain analyses from artificial pollen traps show that evergreen terra firme (well-drained), evergreen terra firme liana, evergreen seasonally inundated, and evergreen riparian rainforests may be readily differentiated, floristically and palynologically. Analogue matching techniques, based on Euclidean distance measures, are employed to compare these pollen signatures with surface sediment pollen assemblages from five lakes: Laguna Bella Vista, Laguna Chaplin, and Laguna Huachi situated within the Madeira-Tapajós moist forest ecoregion, and Laguna Isirere and Laguna Loma Suarez, which are situated within forest patches in the Beni savanna ecoregion. The same numerical techniques are used to compare rainforest pollen trap signatures with the fossil pollen record of Laguna Chaplin. Pollen assemblages of pollen traps situated within riparian forest communities are most similar to surface sediment samples from Lagunas Bella Vista and Chaplin. Pollen derived from terra firme forests also comprises a significant proportion of these assemblages. Together, these pollen spectra successfully identify riparian and terra firme rainforest communities surrounding the two lakes today. Close similarity between terra firme liana pollen trap assemblages and surface samples obtained from Laguna Huachi, a lake surrounded by relatively undisturbed liana forest, suggests liana forest pollen rain may also be identified within lake sediment records. Pollen spectra obtained from surface sediment samples from lakes situated within gallery forests of the Beni savanna ecoregion are significantly different to those obtained from the Madeira-Tapajós ecoregion, reflecting their different floristic compositions. By applying our findings to the previously published Laguna Chaplin Quaternary pollen record, we show that differentiation between riparian and terra firme rainforest pollen assemblages can lead to more robust and detailed palaeovegetation reconstructions than has hitherto been possible.

Baseline study of the leaf‐litter ant fauna in a French Guianese forest

Abstract. 1. Leaf‐litter ants represent a major component of biodiversity and are excellent bioindicators reflecting the health of terrestrial ecosystems. This study, conducted in an unspoiled forest near the Nouragues Research Station, represents the first inventory of leaf‐litter ant diversity conducted in French Guiana, and so can be considered as the baseline dataset for ants in this country.2. Ants were extracted from the leaf‐litter using the Ants of the Leaf Litter Protocol, along an altitudinal gradient at four forest sites, including an inselberg.3. A total of 196 ant species representing 46 genera distributed over eight subfamilies were collected. Four distinct communities spread over a gradient of diversity were thus identified: the liana forest was the most species‐rich (140 species) followed by the forested plateau (102 species), the transition forest (87 species) and the forest at the top of the inselberg (71 species).4. The discovery of species new to science plus several species recorded for the first time in French Guiana, coupled with the particular context of this area, suggests that the Nouragues Research Station might represent a centre of endemism. Once completed, this leaf‐litter ant dataset will contribute greatly to the knowledge of ant biodiversity in French Guiana, and has the potential to progressively become an indispensable tool for country‐wide conservation planning programmes.

Spatial and temporal patterns of gap dominance by low-canopy lianas detected using EO-1 Hyperion and Landsat Thematic Mapper

Woody lianas are critical to tropical forest dynamics because of their strong influence on forest regeneration, disturbance ecology, and biodiversity. Recent studies synthesizing plot data from the tropics indicate that lianas are increasing in both abundance and importance in tropical forests. Moreover, lianas exhibit competitive advantages over trees in elevated CO2 environments and under strong seasonal droughts, suggesting that lianas may be poised to increase not only in abundance but also in spatial distribution in response to changing climate. We used a combination of high-resolution color-infrared videography and hyperspectral imagery from EO-1 Hyperion to map low-lying lianas in Noel Kempff Mercado National Park (NKMNP) in the Bolivian Amazon. Evergreen liana forests comprise as much as 14% of the NKMNP landscape, and low-stature liana patches occupy 1.5% of these forests. We used change vector analysis (CVA) of dry season Landsat TM and ETM+ imagery from 1986 and 2000 to determine changes in liana-dominated patches over time and to assess whether those patches were regenerating to canopy forest. The spatial distribution of liana patches showed that patches were spatially aggregated and were preferentially located in proximity to waterways. The CVA results showed that most of the dense liana patches increased in brightness and greenness and decreased in wetness over the 14 years of the change analysis, while non-liana forest patches changed less and in more random directions. Persistent liana patches increased in area by an average of 59% over the time period. In comparison, large burned areas appeared to recover completely to canopy forest in the same time period. This suggests that the dense liana patches of NKMNP represent an alternative successional pathway characterized not by tree regeneration but rather by a stalled state of low-canopy liana dominance. This research supports hypotheses that liana forests can be a persistent rather than transitional component of tropical forests, and may remain so due to competitive advantages that lianas enjoy under changing climatic conditions.

Multivariate analysis of organismal and habitat parameters in two neotropical primate communities.

This paper investigates the interrelations of some organismal and habitat parameters in two platyrrhine primate communities in French Guiana and Ecuadorian Amazonia. Fifteen habitat and organismal parameters and body weight were retained after a preliminary analysis, on the basis of frequent use and constraints reflected in anatomical specializations. The 16 parameters for 13 platyrrhine species were used for a series of principal components analyses (PCAs). All PCAs on separate or combined communities provided comparable results. The Atelinae, Ateles, Alouatta, and Lagothrix, were clustered together with Pithecia, associated with canopy, mature forest, frugivory, and (to a lesser degree) climb/suspensory locomotion. On the other hand, the three species of Cebus usually formed a loose cluster, located in the center of the cloud of species. Lastly, the Callitrichinae, involving two species of Saguinus and Cebuella, were relatively dispersed and frequently associated with liana forest, lianas, understory, and faunivory. However, Cebuella was consistently isolated and associated with liana forest, lianas, body weight, understory, and vertical supports. In this way, clusters appeared to conform to the major platyrrhine taxonomic groups, supporting the fact that basic ecological and behavioral adaptations have evolved in a phylogenetic context. In addition, the analyses revealed that body weight, forest type and layer, feeding behavior, and locomotion are the most important variables that have apparently shaped or driven the adaptive zones of extant platyrrhines.

Diversity and guild structure of the Petit Saut bird community

Bird communities were sampled at different scales at Saint-Eugène and on the Petit Saut dam reservoir between 1993 and 1 996. Global bird species richness of the Petit Saut area (ca . 35 sq. km investigated) was estimated to be over 400 species, of which 342 were observed. Relationships between species richness and surveyed area, sampling pressure, and habitat diversity, are described. A majority of species showed low contact frequencies and low abundance. Numerically dominant species on the mainland were also abundant on islands, but islands had a different pool of dominant species. Migrants accounted for a very small proportion of the community and were mainly aquatic birds, but the frequency of migrants in primary rainforest may be underestimated. Community organization is described in terms of guilds, feeding habits, habitats and social systems. Sixteen guilds can be identified. Insectivores are dominant in the bird community. Most species inhabit terra firme forest, but some guilds are preferentially associated with damp or liana forests. Thirty percent of the bird species live in single-species or mixed-species groups, in particular in canopy-, understory-, or ant-following flocks. The ecological organization of the Petit Saut bird community is similar to that found in other Guianan or Amazonian forest sites. Flooding of the reservoir lead to a very slow increase of aquatic bird diversity and abundance, particularly of Sungrebe (Heliomis fulica), while sightings of banks-dwelling species became scarce.

Cost and Efficiency of Cutting Lianas in a Lowland Liana Forest of Bolivia1

ABSTRACTLiana cutting is a commonly suggested silvicultural practice aimed at reducing the negative impacts of lianas on timber production, but few experimental studies have been conducted to evaluate the cost and efficiency of this practice. In this study, we estimated the cost of cutting lianas in 12 plots of 0.25 ha each in a densely liana‐infested forest of lowland Bolivia, and evaluated the efficiency of this silvicultural treatment in terms of the proportion of lianas missed, the density of resprouting liana stumps, and the number of liana‐infested trees after two years of an experimental liana treatment.The cost of cutting lianas in this forest by locally hired laborers was 23.6 (SE = 2.48) person‐hours/ha. Considering local cost of labor and the U.S.–Bolivian currency exchange rate at the time of the study, this figure translates to ca$15/ha. Liana density decreased from 2471 (SE = 104.3) to 130 (SE = 24.2) liana stems &gt;2 cm/ha immediately after cutting, because 5.5 percent of lianas were left uncut (missed). Slender lianas were missed more often than lianas with large‐diameter stems. Liana species that grow 2–3 m before they start to twine were also frequently missed. Twenty‐two percent of liana stumps a2 cm sprouted after cutting. Liana stumps with larger diameters sprouted more than stumps with smaller diameters. Most liana stumps produced only two sprouts. Two years after cutting, 78 percent of trees had no living lianas in their crowns, in contrast to only 13 percent liana‐free trees in the control plots. Sixty‐four percent of trees still had hanging dead lianas two years after cutting, but only 23 percent of trees were reinvaded by lianas using dead liana stems as trellises.Liana cutting can efficiently reduce the number of lianas in liana‐infested forests, and the effects of cutting lianas last for at least two years; however, the treatment is expensive. Thus, we recommend that it is better to view liana cutting as a preventive activity to avoid liana infestation, rather than as a corrective measure after poor management. Liana cutting can be easily conducted along with other reduced‐impact logging practices.RESUMESEl corte de lianas es una práctica de manejo comunmente recomendada para reducir los impactos negatives de las lianas en la producción forestal, pero existen pocos estudios experimentales que evaluen los costos y la eficiencia de dicha práctica. En este estudio estimamos el costo del corte de lianas en 12 parcelas de 0.25 ha cada una en un bosque densamente infestado de lianas en Bolivia, y evaluamos la eficiencia de este tratamiento en términos de la proporción de lianas no cortadas, de la densidad de lianas que rebrotan, y el número de árboles infestados con lianas dos años despues de un tratamiento del corte experimental de lianas.El costo de cortar lianas en este bosque por trabajadores locales fue de 23.6 (EE=2.48) horas‐persona/ha. Considerando el costo de labor y el intercambio monetario entre Bolivia y los EUA al tiempo del experimento, esta figura se traduce a ca 15 dólares EUA/ha. La densidad de lianas se redujo de 2471 (EE=104.3) a 130 (EE = 24.2) tallos de liana ≥2 cm/ha inmediatamente despues del corte, porque 5.5 por ciento de las lianas no se cortaron. Las lianas más delgadas fueron cortadas con mayor frequencia que las lianas más gruesas. Las especies de lianas que crecen

Lianas and Trees in a Liana Forest of Amazonian Bolivia1

ABSTRACTThe distribution of lianas (woody climbing plants) on trees in a lowland “liana forest” of northeastern Bolivia was clumped and varied with characteristics of individual trees and tree neighbors. In twenty‐four 900‐m2 square plots established to estimate tree (a 10 cm DBH [diameter at breast height]) and liana (≥2 cm DBH) densities and to count the number of lianas a tree carried, we estimated a mean of 65 tree species and 51 liana species per hectare. Mean tree density at the study site (564 trees/ha, SE = 23.7) was similar to other tropical sites, but mean liana density was much higher (2471 lianas/ha, SE = 104.3). Basal area of trees ≥10 cm DBH was low in Oquiriquia (19.2 m2/ha) in comparison to other tropical forests. Liana diversity, as expressed by the ratio of liana/tree species, was higher in this forest than in any other so far reported. Of trees ≥10 cm DBH, 86 percent carried lianas. Four tree species (Astrocaryum aculeatum, Euterpe precatoria, Xylopia sericea, and Astronium fraxinifolium) had a lower proportion of liana‐infested individuals than expected based on the mean percent of liana infestation in this forest. Forest plots with similar tree species composition did not have similar liana composition or liana loads per tree, which suggests that lianas and trees have no specific associations with each other. Lianas showed an aggregated distribution on trees, suggesting a facilitation process in which new lianas use already established ones to climb trees. Lianas of four different climbing mechanisms climbed a similar number of trees. Plots in the forest with high palm density also had high liana density, suggesting that palms and lianas respond positively to common forest conditions in the study site (perhaps related to successional forest status). Larger‐diameter trees carried more lianas than slender trees, but this relationship was affected by the density of trees 10–30 cm DBH surrounding each tree, which suggests again that the successional stage of the forest in which a tree grows affects the number of lianas a tree carries. We found little evidence to support the idea that lianas were more likely to climb some tree species than others. Instead, larger trees and trees growing in the vicinity of trees 10–30 cm DBH, tended to have more lianas, perhaps as result of longer exposure to liana infestation.RESUMESLa distributión de lianas (bejucos leñosos) en los árboles de un “bosque de lianas” en el noreste de Bolivia fué agregada y varió de acuerdo a características individuates y del vecindario en que crecía cada árbol. En veinticuatro parcelas cuadradas de 900 m2 establecidas para estimar las densidades de árboles (≥ 10 cm DAP) y lianas (≥2 cm DAP), y contar el número de lianas por árbol, estimamos un promedio de 65 especies de árboles y 51 especies de lianas por ha. La densidad promedio de árboles en el sitio de estudio (564 árboles/ha, EE=23.7) fué similar a otros sitios tropicales, pero la densidad promedio de bejucos leñosos fué mucho más alta (2471 bejucos lefiosos/ha). El área basal de árboles ≥ 10 cm DAP fué baja en Oquiriquia (19.2 m2/ha) en comparación con otros bosques tropicales. La diversidad de lianas, expresada como la razón de especies de árboles/especies de lianas lefiosas, fué mayor que en cualquier otro estudio reportado hasta la fecha. De los árboles ≥ 10 cm DAP, 86 por ciento cargaban lianas. Cuatro especies de árboles (Astrocaryum aculeatum, Euterpe precatoria, Xylopia sericea, y Astronium fraxinifolium), tuvieron una proporción menor de individuos infestados con lianas que lo esperado en base el porcentaje promedio de infección de lianas en este bosque. Parcelas de bosque con una composición de especies de árboles similar no compartieron una compositión de lianas similar, ni una carga de bejucos similar por árbol, lo que suguiere que las lianas y los árboles no tienen asociaciones especificas entre sí. Las lianas presentaron un partón agregado en los árboles, lo que sugiere un proceso de facilitación en el que nuevas lianas emplean a otras ya establecidas para trepar en los árboles. Lianas de cuatro mecanismos distintos para trepar subieron un número similar de árboles. Parcelas del bosque con altas densidades de palmas mostraron altas densidades de bejucos, lo que sugiere que las palmas y los bejucos responden positivamete a condiciones sucesionales del bosque similares. Arboles de diámetros mayores cargaban más lianas que

Effect of Liana Cutting on Tree Regeneration in a Liana Forest in Amazonian Bolivia

Effect of Liana Cutting on Tree Regeneration in a Liana Forest in Amazonian Bolivia

EFFECT OF LIANA CUTTING ON TREE REGENERATION IN A LIANA FOREST IN AMAZONIAN BOLIVIA

Lianas, woody climbing plants, are a conspicuous component of tropical forest canopies that might affect prevailing conditions in the forest floor and thus impact tree seedling regeneration. The effects of lianas on tree seedling survival, growth, and density were studied in a lowland liana forest in Bolivia. Gravimetric soil water content and canopy openness were measured to evaluate whether these factors changed as a result of liana cutting. I established 24 square plots of 900 m2 each, and after an initial set of measurements, all lianas were cut in half of them, while the others plots were used as controls. Tree seedling growth and survival of two tree species were evaluated: Clarisia ilicifolia and Astronium fraxinifolium. Eighteen months after liana cutting, seedlings in liana-cut plots grew significantly taller and produced more leaves than did seedlings in control plots, but survival was not affected by treatment. Seedling growth following liana cutting was significantly higher in A. fraxinifolium...

Lianas and Trees in a Liana Forest of Amazonian Bolivia1

Abstract The distribution of lianas (woody climbing plants) on trees in a lowland “liana forest” of northeastern Bolivia was clumped and varied with characteristics of individual trees and tree neighbors. In twenty-four 900-m2 square plots established to estimate tree (≥10 cm DBH [diameter at breast height]) and liana (≥2 cm DBH) densities and to count the number of lianas a tree carried, we estimated a mean of 65 tree species and 51 liana species per hectare. Mean tree density at the study site (564 trees/ha, SE = 23.7) was similar to other tropical sites, but mean liana density was much higher (2471 lianas/ha, SE = 104.3). Basal area of trees ≥10 cm DBH was low in Oquiriquia (19.2 m2/ha) in comparison to other tropical forests. Liana diversity, as expressed by the ratio of liana/tree species, was higher in this forest than in any other so far reported. Of trees ≥10 cm DBH, 86 percent carried lianas. Four tree species (Astrocaryum aculeatum, Euterpe precatoria, Xylopia sericea, and Astronium fraxinifoliu...

Cost and Efficiency of Cutting Lianas in a Lowland Liana Forest of Bolivia1

Liana cutting is a commonly suggested silvicultural practice aimed at reducing the negative impacts of lianas on timber production, but few experimental studies have been conducted to evaluate the cost and efficiency of this practice. In this study, we estimated the cost of cutting lianas in 12 plots of 0.25 ha each in a densely liana-infested forest of lowland Bolivia, and evaluated the efficiency of this silvicultural treatment in terms of the proportion of lianas missed, the density of resprouting liana stumps, and the number of liana-infested trees after two years of an experimental liana treatment.The cost of cutting lianas in this forest by locally hired laborers was 23.6 (SE = 2.48) person-hours/ha. Considering local cost of labor and the U.S.–Bolivian currency exchange rate at the time of the study, this figure translates to ca $15/ha. Liana density decreased from 2471 (SE = 104.3) to 130 (SE = 24.2) liana stems ≥2 cm/ha immediately after cutting, because 5.5 percent of lianas were left uncut (missed). Slender lianas were missed more often than lianas with large-diameter stems. Liana species that grow 2–3 m before they start to twine were also frequently missed. Twenty-two percent of liana stumps ≥2 cm sprouted after cutting. Liana stumps with larger diameters sprouted more than stumps with smaller diameters. Most liana stumps produced only two sprouts. Two years after cutting, 78 percent of trees had no living lianas in their crowns, in contrast to only 13 percent liana-free trees in the control plots. Sixty-four percent of trees still had hanging dead lianas two years after cutting, but only 23 percent of trees were reinvaded by lianas using dead liana stems as trellises.Liana cutting can efficiently reduce the number of lianas in liana-infested forests, and the effects of cutting lianas last for at least two years; however, the treatment is expensive. Thus, we recommend that it is better to view liana cutting as a preventive activity to avoid liana infestation, rather than as a corrective measure after poor management. Liana cutting can be easily conducted along with other reduced-impact logging practices.

A New Species of Ditassa (Asclepiadaceae) from Espírito Santo, Brazil

Ditassa oberdanii, a new species of Asclepiadaceae from remnant patches of Atlantic rainforest in Espirito Santo state, southeastern Brazil, is described, illustrated, and compared to D. oxyphylla Turczaninow, a similar species that is found in Brazil, Colombia, and Venezuela. A survey of the Asclepiadaceae of Espirito Santo, Brazil, turned up 44 species belonging to 16 genera. The largest genus is Ditassa with 11 species, including D. oberdanii. This species is found in remnant patches of lower montane rainforest in southeastern Brazil, in the Atlantic forest biome which is seriously threatened by human activities. Ditassa oberdanii Fontella & Alvarez, sp. nov. TYPE: Brazil. Espfrito Santo: Santa Teresa, Rio Saltinho, 500 m, 26 Apr. 1984, Pizziolo 22 (holotype, MBML; isotype, HB). Figure 1. Species nova D. oxyphyllae Turczaninow affinis, sed imprimis foliis linear-lanceolatis angustioribus, corollae lobis extus glabris et longioribus, caudiculis non geniculatis, polliniis ellipticis vel subellipticis et latioribus differt. Vines; stems hirsute-tomentose. Leaves with flattened petioles, hirsute above, glabrescent beneath, 7-10 mm long; blade linear-lanceolate, glabrous to glabrescent with secondary nerves rectilinear, base cuneate with two glands at petiole juncture, apex acuminate, 61-69 X 10-13 mm. Inflorescence an umbelliform cyme, extra-axillary, 3-6-flowered; peduncles hirsute-tomentose, 1-2 mm. Flowers white; pedicels hirsute, 2-4 mm long. Calyx deeply lobed; lobes ovate-lanceolate, hirsute outside, glabrous inside, margins hyaline, 2-2.5 X 1-1.5 mm, with 1-2 minute inside glands at base of each sinus; corolla subcampanulate; tube glabrous outside, pubescent inside, 0.8-1.0 mm long; lobes linear-lanceolate, glabrous outside, pubescent inside on upper half at margin, with longer hairs at apex, 4-5 X 1-1.3 mm. Corona lobes filiform, twice the length of the gynostegium, upper part papillose, the outer 3-3.2 X 0.1-0.3 mm, apex slightly curved, the inner 3.5-4 X 0.2-0.3 mm, apex curving inward. Anthers rectangular or subrectangular, ca. 0.75 x 0.57 mm, appendages membranaceous, suborbicular, ca. 0.42 mm long. Corpusculum ovate, 0.20-0.22 x 0.08-0.09 mm; translator arms filiform, 0.06-0.09 mm long; pollinia elliptic or subelliptic, longer than corpusculum, slightly curved, 0.24-0.28 x 0.09-0.17 mm. Stigmatic appendix apiculate. This new species is related to Ditassa oxyphylla Turczaninow, from which it differs mainly by the linear-lanceolate leaves, longer corolla lobes (4-5 mm), which are glabrous outside, straighter translator arms, and wider (0.09-0.17 mm), elliptic to subelliptic pollinia. In contrast, D. oxyphylla has ovate-lanceolate to elliptic leaves, corolla lobes 23 mm long, geniculate translator arms, and oblong to subclavate pollinia (0.06-0.08 mm wide). Ditassa oxyphylla is found in Colombia, Venezuela, and Brazil, where it occurs in Pernambuco, Alagoas, and Bahia states; in Bahia it is found in caatinga, remnant liana forest (Mata de Cip6) and pastures, from 500-600 m above sea level (Pereira & Silva, 1973; Pereira et al., 1989). Ditassa oberdanii is named in honor of Oberdan Jose Pereira, Professor of Botany at the Espirito Santo Federal University (UFES), who has contributed greatly to the study of the flora of Espirito Santo, Brazil. Acknowledgments. We thank the CNPq for Jorge Fontella-Pereira's research fellowship, the curators of R, RB, GUA, MBML, VIES, and CVRD, Dorothy Sue Dunn de Araujo for the translation of the text into English, and Gloria Gongalves for the sketch.

Natural forest disturbance and change in the Brazilian Amazon

Abstract Landsat Thematic Mapper images covering the entire 3.9 million km2 of forested Brazilian Amazon reveal natural change and disturbance occurring on a scale of decades to centuries. These include: 92,000 km2 of bamboo forests undergoing synchronous mortality and regrowth; 1500 km2 of recently active dune fields; 900 km2 of recent downburst blowdowns; > 500 km of recent forest fire scars; and an unknown area of forest mortality from flooding of high ground and alluvial forests. Fire subclimax fern savannas created by Yanoama Indians cover an additional 600 km2. Natural and indigenous disturbances and synchronized phenologies are therefore responsible for a dynamic spectral bahavior in large portions of the Amazon Basin. Disturbances and disturbance indicators not easily detected include blowdown sites > 30 yrs old, blowdowns < 30 hectares in size, liana forests and babassu palm forests.

Evidence for the Successional Status of Liana Forest (Xingu River Basin, Amazonian Brazil)

Our first objective was to describe species richness, relative density, relative frequency, relative dominance, species importance, and family importance in the two study sites for all individuals ≥10 cm dbh. Our second objective was to show how the adaptations of some of the ecologically most important species in these study sites offer support to the hypothesis that liana forest is not a primary forest type, but rather anthropogenic