Tierra Firme Forest Research Articles

Using foraging ecology to elucidate the role of species interactions in two contrasting mixed-species flock systems in northeastern Peru

Mixed-species flocks are formed on the basis of both positive and negative species interactions. We use foraging behavior in two different flock types to interpret the extent to which core species minimize niche overlap to reflect negative interactions. We also use the foraging behavior of alarm-calling species to infer whether their behavior is consistent with predictions for species that accrue benefits by associating with other flocking species. The foraging patterns of core species in tierra firme flocks show large differences with respect to foraging maneuvers and substrates, a finding that is consistent with niche theory. In igapó (a blackwater seasonally inundated forest), only the alarm-calling species show differences in foraging patterns among core flock members. We also show that alarm-calling species in different sites show different patterns of association with other flocking species: one species, Thamnomanes saturninus, shows no strong tendency to associate with any other species in the flock and the other, Thamnomanes schistogynus, perches close to and immediately below other species in the flock. These observations are consistent with the hypothesis that alarm-callers benefit from insects flushed from other flock members in igapó forest but not in tierra firme forest. In northeastern Peru, subtle variation in the foraging behaviors among alarm-calling species in tierra firme and igapó flocks may reflect differences in species interactions among key flock members.

Regeneration and management of lesser known timber species in the Peruvian Amazon following disturbance by logging

Following the principles of Reduced Impact Logging (RIL) the construction of roads and log landings together with logging gaps are the most profound direct impacts that a forest operation has on the forest. While the effects of logging gaps have been studied in detail, the impacts of road and log landing construction, and how the forest regenerates after such disturbances, remain poorly understood. This paper investigates the regeneration success of a range of well/lesser-known timber species in a tierra-firme forest concession in Peru. Sample plots (100m2) were established in areas with three different types of logging induced disturbances: skid trails caused by log extraction, secondary roads and log landings/patios. Seedling establishment of 16 different commercially targeted species groups was examined for these three types of disturbances using a chronosequence of 5years. As 100 plots were inventoried for each type of disturbance an area of 3 hectares was sampled in total. The regenerative success was compared across disturbance categories, and each species’ response to environmental variables was investigated using zero-inflated negative binomial regression. Regenerative success varied across species groups, with the majority either regenerating significantly better at the least disturbed sites (n=6) or showing statistically indistinguishable results (n=9) because of limited regeneration. One species group, Cariniana spp., regenerated best at intermediate sites. The varying response across species groups indicates a need for a more varied forest management. For species with poor regeneration it is recommended to plant saplings (enrichment planting) to ensure forest recovery and species preservation at the landscape level.

Patrones de distribución de especies arbóreas de dosel y sotobosque a escala local en bosques de tierra firme, Amazonia colombiana

The effect of environmental variation on the structure of tree communities in tropical forests is still under debate. There is evidence that in landscapes like Tierra Firme forest, where the environmental gradient decreases at a local level, the effect of soil on the distribution patterns of plant species is minimal, happens to be random or is due to biological processes. In contrast, in studies with different kinds of plants from tropical forests, a greater effect on floristic composition of varying soil and topography has been reported. To assess this, the current study was carried out in a permanent plot of ten hectares in the Amacayacu National Park, Colombian Amazonia. To run the analysis, floristic and environmental variations were obtained according to tree species abundance categories and growth forms. In order to quantify the role played by both environmental filtering and dispersal limitation, the variation of the spatial configuration was included. We used Detrended Correspondence Analysis and Canonical Correspondence Analysis, followed by a variation partitioning, to analyze the species distribution patterns. The spatial template was evaluated using the Principal Coordinates of Neighbor Matrix method. We recorded 14 074 individuals from 1 053 species and 80 families. The most abundant families were Myristicaceae, Moraceae, Meliaceae, Arecaceae and Lecythidaceae, coinciding with other studies from Northwest Amazonia. Beta diversity was relatively low within the plot. Soils were very poor, had high aluminum concentration and were predominantly clayey. The floristic differences explained along the ten hectares plot were mainly associated to biological processes, such as dispersal limitation. The largest proportion of community variation in our dataset was unexplained by either environmental or spatial data. In conclusion, these results support random processes as the major drivers of the spatial variation of tree species at a local scale on Tierra Firme forests of Amacayacu National Park, and suggest reserve's size as a key element to ensure the conservation of plant diversity at both regional and local levels.

Regeneration in canopy gaps of tierra-firme forest in the Peruvian Amazon: Comparing reduced impact logging and natural, unmanaged forests

Reduced impact logging (RIL) has been promoted as a cornerstone in sustainable forest management in the tropics, although the ecological implications of RIL guidelines are poorly understood. This study aims to identify the impact of RIL on the regeneration of commercial timber species by comparing the regeneration dynamics of logging gaps with naturally occuring canopy gaps. In the concession of Consorcio Forestal Amazonico in the region of Ucayali in the Peruvian Amazon, a total of 210 circular sample plots were established in 35 gaps in unmanaged natural forest and 35 canopy gaps in forest managed according to RIL guidelines. The size of each canopy gap was estimated by establishing a polygon that followed the vertical projection of the edge of the gap. Three circular plots of 100 m2 were established within each canopy gap. The center points of the plots were placed at the stump, mid-trunk and crown of the fallen tree. It appeared that the total abundance of seedlings did not differ significantly between logging gaps and natural canopy gaps. Instead the response to logging varied between species groups. The Clarisia sp. species group had a significant negative response to logging, while Ormosia sp., Aniba sp., Ocotea sp., Qualea sp. and Terminalia sp. were significantly more abundant in gaps of logged-over forest. A direct effect of seed tree retention on seedling abundance could not be detected statistically. Possible reasons for observed differences between untouched and logged forest and consequences of observed patterns for long-term forest development and management were discussed. It was concluded that issuing and enforcing strict guidelines on sustainable forest management is no guarantee for preserving species composition in tropical forests.

Densidad poblacional, estimaciones de abundancia, preferencia de hábitat y la estructura social de los delfines del Río Amazonas (Inia geoffrensis) en la Reserva Cuyabeno, Ecuador

La densidad poblacional, abundancia y preferencia de hábitat del delfín Amazónico o Boto (Inia geoffrensis) en la Reserva Cuyabeno, Ecuador fue estudiado entre 1996 y 1998. El área de estudio se ubicó en el río Cuyabeno y en el río Lagartococha, dos tributarios de aguas negras los cuales desembocan al rio Aguarico. El río Cuyabeno en sus 111 km estudiados fluye a través de bosques de tierra firme con numerosas lagunas meandricas, mientras que el río Lagartococha a lo largo de los 86,7 km que fueron estudiados se encuentra en un sistema de bosques inundados. La máxima densidad poblacional de 0,39 Botos/km río es bastante bajo en comparación con otras áreas de estudio de la Amazonía baja y depende significativamente de la estación del año y el hábitat. En la época seca, la mayoría de los animales tienden a mantenerse cerca de las desembocaduras de los ríos, mientras que en la época lluviosa suben a las lagunas con Igapó y Varzea. Existe mayor diversidad de comportamientos en lagunas con Igapó y Varzea, mientras que los delfines usan las secciones de río de poca profundidad y playas solamente como pasos migratorios.
 A pesar de que los Botos se consideran animales solitarios, observaciones en la Reserva Cuyabeno confirman un gran porcentaje de grupos de dos a ocho animales. Cuando hay crías, generalmente el tamaño del grupo es de tres a cuatro animales. El ámbito hogareño de los Botos en la Reserva Cuyabeno, según los estudios de foto identificación, se extiende a través de varios ríos entre el río Lagartococha y el río Cuyabeno con una extensión de más de 200 km, sin embargo, la mayoría de los delfines se mantuvo en un rango de 50km en sobre posición con otros grupos o delfines solitarios.

Classification of Amazonian primary rain forest vegetation using Landsat ETM+ satellite imagery

A lack of spatially and thematically accurate vegetation maps complicates conservation and management planning, as well as ecological research, in tropical rain forests. Remote sensing has considerable potential to provide such maps, but classification accuracy within primary rain forests has generally been inadequate for practical applications. Here we test how accurately floristically defined forest types in lowland tropical rain forests in Peruvian Amazonia can be recognized using remote sensing data (Landsat ETM+ satellite image and STRM elevation model). Floristic data and a vegetation classification with four forest classes were available for eight line transects, each 8 km long, located in an area of ca 800 km 2. We compared two sampling unit sizes (line transect subunits of 200 and 500 m) and several image feature combinations to analyze their suitability for image classification. Mantel tests were used to quantify how well the patterns in elevation and in the digital numbers of the satellite image correlated with the floristic patterns observed in the field. Most Mantel correlations were positive and highly significant. Linear discriminant analysis was used first to build a function that discriminates between forest classes in the eight field-verified transects on the basis of remotely sensed data, and then to classify those parts of the line transects and the satellite image that had not been visited in the field. Classification accuracy was quantified by 8-fold crossvalidation. Two of the tierra firme (non-inundated) forest types were combined because they were too often misclassified. The remaining three forest types (inundated forest, terrace forest and Pebas formation/intermediate tierra firme forest) could be separated using the 500-m sampling units with an overall classification accuracy of 85% and a Kappa coefficient of 0.62. For the 200-m sampling units, the classification accuracy was clearly lower (71%, Kappa 0.35). The forest classification will be used as habitat data to study wildlife habitat use in the same area. Our results show that remotely sensed data and relatively simple classification methods can be used to produce reasonably accurate forest type classifications, even in structurally homogeneous primary rain forests.

<p><strong>Bryophyte diversity patterns in flooded and tierra firme forests in the Araracuara Region, Colombian Amazonia</strong></p>

We investigated patterns of bryophyte species richness and composition in two forest types of Colombian Amazonia, non-flooded tierra firme forest and floodplain forest of the Caquetá River. A total of 109 bryophyte species were recorded from 14 0.2 ha plots. Bryophyte life forms and habitats were analyzed, including the canopy and epiphylls. Bryophyte species did not show significant differences between landscapes but mosses and liverworts were different and with opposite responses balancing the overall richness. Independence test showed differences in both life form and habitat use distribution between the two forest types with more fan and mat bryophytes species in the floodplains, and more epiphytic liverworts in the tierra firme forest. Correspondence analysis showed differences in the bryophyte species assemblage between the two forest types where they may be responding to the higher humidity provided by the flooding. Despite of, the environmental differences detected, epiphyll species assemblages were not strongly affected. Apparently, epiphyll habitat is stressful enough to hide the environmental differences between the flooded and Tierra firme forests.

LEAF DEMOGRAPHY AND PHENOLOGY IN AMAZONIAN RAIN FOREST: A CENSUS OF 40 000 LEAVES OF 23 TREE SPECIES

The periodicity, synchrony, and causes of variability in the demography of tree leaves in ecosystems with relatively aseasonal climates, such as tropical rain forests, is still poorly understood. To address this issue, we surveyed the timing of birth and death of >40 000 leaves of 1445 individuals of 23 evergreen rain forest species in several late primary and early secondary successional plant communities at San Carlos de Rio Negro, Venezuela, in the northern Amazon basin. In all species, the mortality rate generally increased with leaf age. However, in many species, deceleration of death rates with extreme leaf age was noted. In general, for each species, the age structure of leaf populations and the frequency distribution of leaf life span were broad. Species differed substantially in their leaf demography. Measured in their native habitats, seven species common to disturbed open sites had shorter median life spans (0.7 yr) than five species common to open but infertile Bana primary communities (1.9 yr average) or six species common to two tall primary forest communities (Tierra Firme and Caatinga), when measured in high-light conditions in the canopy (2.0 yr average). Variation in light availability had consistent effects on leaf life span in all species. Species native to Tierra Firme forest had average leaf life spans of 3.2, 1.9, and 1.6 yr, respectively, in deeply shaded understory microsites, in small gaps, and in sunlit mature tree canopies. Species native to Caatinga forest had average leaf life spans of 4.2, 3.4, and 2.5 yr, respectively, in these same microsite types. Two species common in gaps and in disturbed sites had much longer leaf life span in shaded understory than in open, disturbed microsites. For all species, responses were similar when trees were planted in sites differing in light availability, as when trees naturally established across light gradients. The rate of leaf production, the risk of leaf mortality, and the leaf life span were not periodic or related consistently to seasonality of climate. Negligible relationships existed between the mild annual dry season and either leaf production or leaf mortality in all species. Thus, leaf phenology and demography were essentially aseasonal in this tropical forest environment.

LINKING FLORISTIC PATTERNS WITH SOIL HETEROGENEITY AND SATELLITE IMAGERY IN ECUADORIAN AMAZONIA

Florisitic ground surveys in tropical rain forests are laborious and time consuming, so we tested to what degree reflectance differences visible in Landsat Thematic Mapper (TM) satellite images can be used to predict differences in florisitic composition and species richness among rain forest sites. To gain ecological understanding of the rain forest ecosystem, we also tested to what extent variation in these vegetation characteristics can be explained by edaphic site conditions. The study was conducted in a relatively homogeneous area of Amazonian rain forest in Yasuni National Park, Ecuador. We established 27 transects of 5 m × 500 m within an area of ∼20 km × 25 km to study edaphic and floristic patterns mainly within the tierra firme (non-inundated) forest. In each transect, soil samples were collected for chemical and textural analyses, and the abundance of each species belonging to two understory plant groups, pteridophytes (ferns and fern allies) and the Melastomataceae, was assessed. Floristic similarity between transect pairs varied widely and ranged from almost no overlap in species composition to very high overlap. The among-transect floristic similarity patterns of the two plant groups were strongly correlated with each other no matter whether presence–absence or abundance data were used. The floristic similarity patterns were also strongly correlated with the similarity in pixel values of the infrared bands in the Landsat TM satellite image and with the similarity in most of the measured soil variables. Similarity in species richness, on the contrary, was neither correlated with similarity in pixel values nor with similarity in most of the soil variables. We conclude that reflectance patterns in satellite images can be efficiently used to predict landscape-scale floristic and edaphic patterns in tierra firme rain forest. Predicting patterns in species richness, on the other hand, is not possible in the same straightforward manner. These results have important practical implications for land use and conservation planning as well as for ecological and biodiversity research. Corresponding Editor: C. A. Wessman.

Dissecting Amazonian Biodiversity

Biogeographical and biodiversity studies in Iowland Amazonian rain forests typically refer to observed or postulated distribution barriers such as past unfavorable climates, mountains, rivers, and river floodplains that divide the uniform tierra firme (noninundated) forest. Present-day ecological heterogeneity within tierra firme has hardly been discussed in this context, although edaphic differences are known to affect species distribution patterns in both inundated areas and tierra firme. Quantification of landscape heterogeneity in Peruvian Iowland Amazonia (500,000 kilometers squared), based on field studies and satellite image analysis, shows that Peruvian Amazonia is considerably more heterogeneous than previously reported. These observations have implications for the research, management, and conservation of Amazonian biodiversity.

Growth and mortality of trees in Amazonian tropical rain forest in Ecuador

Abstract. Structural changes are analysed in four samples representing 4 ha, two line transects and two hectare plots, of Amazonian tropical lowland rain forest in northern Ecuador. Only trees with a DBH ≥ 10 cm were included. A sample of floodplain forest in Añangu represents the largest turnover found in tropical forests (stand half‐life = 23 yr). The line transect and hectare plot both of tierra firme forest in Añangu have the same turnover (37 yr) and were balanced for death and in‐growth of both individuals and wood (basal area). The 1‐ha tierra firme sample in Cuyabeno had a turnover of 67 yr and was in a growing phase. The floodplain line transect in Añangu was in a phase of structural breakdown. However, the floodplain line transect had the largest growth of basal area per tree (23.4 cm2/yr). The tierra firme samples had a growth of 9.6, 10.1, and 13.6 cm2/yr. Most of the dead trees fell with some uprooting in three of the four samples. However, no significant difference in the distribution of mode of death was found between the four samples. Death was independent of topography and the dead trees were randomly distributed. As the trees grow up they occupy more space and larger trees (DBH ≥ 15 cm) become more uniformly distributed, whereas smaller trees (DBH ≤ 15 cm) were randomly distributed. Our study confirms that plots of 1 ha are not sufficient to include representative samples of different stages of forest structure.

Nutrient dynamics within amazonian forests : II. Fine root growth, nutrient availability and leaf litter decomposition.

Relationships between fine root growth, rates of litter decomposition and nutrient release were analysed in a mixed forest on Tierra Firme, a Tall Amazon Caatinga and a Low Bana on podsolized sands near San Carlos de Rio Negro. Fine root growth in the upper soil layers (root mat+10 cm upper soil) was considerably higher in the Tierra Firme forest (1117 g m-2 yr-1) than in tall Cattinga (120) and Bana (235). Fine root growth on top of the root mat was stimulated significantly by added N in Tall Caatinga and Low Bana forests, by P in Tierra Firme and Bana forests, and by Ca only in the Tierra Firme forest. Rate of fine root growth in Tierra Firme forest on fresh litter is strongly correlated with the Mg and Ca content of litter. Rate of litter decomposition was inversely related to % lignin and the lignin/N ratio of litter. Litter contact with the dense root mat of the Tierra Firme increased rates of disappearance for biomass, Ca and Mg as compared with litter permanently separated or lifted weekly from the root mat to avoid root attachment. Nitrogen concentration of decomposing litter increased in all forests, net N released being observed only in Caryocar glabrum and Aspidosperma megalocarpum of the Tierra Firme forest after one year of exposure. Results emphasize the differences in limiting nutrients in amazonian forest ecosystems on contrasting soil types: Tierra Firme forests are particularly limited by Ca and Mg, while Caatinga and Bana forests are limited mainly by N availability.

Nutrient dynamics within amazonian forest ecosystems

A comparative analysis on the rate of fine litterfall and its associated nutrient fluxes was carried out in a mixed forest on Tierra Firme, a tall Amazon Caatinga and a Bana on podsolized sands near San Carlos de Rio Negro. There was seasonality in leaf fall and total litterfall in mixed forest and tall Amazon Caatinga forest but no definite trend in the Bana. Litterfall curves were significantly correlated among sites indicating common regulating factors in the three forests. Leaf litter from mixed forest on Tierra Firme was richer in N with extremely low Ca and Mg concentrations; tall Amazon Caatinga litter had higher P and Mg concentration, while Bana litter was low in N but K concentration was twice as high as in the other two forests. Annual fine litterfall in Tierra Firme mixed forest was nearly 4 times higher than in Bana, But N flux was 10 times higher, while Ca and Mg fluxes were similar. Tall Amazon Caatinga had Ca and Mg fluxes in litterfall 2-3 times higher than the other two forests. Within-stand efficiency of nitrogen, calcium and magnesium use, as measured by biomass/nutrient ratios, differentiates Tierra Firme from Caatinga and Bana forest: Tierra Firme has the lowest N, but the highest Ca and Mg use efficiencies. Higher P use efficiency was measured in Bana followed by Tierra Firme and Caatinga; while Tierra Firme and Caatinga showed similar higher K use efficiencies than Bana. N/P ratios indicates that Tierra Firme forest is limited by P availability, while low N availability predominates in Caatinga. Bana appears limited by both N and P. These differences probably relate to variations in degree of sclerophylly and leaf duration which determine leaf nutrient concentrations in the ecosystems studied.

Liana Biomass and Leaf Area of a "Tierra Firme" Forest in the Rio Negro Basin, Venezuela

In evergreen tropical rain forest, growing on a nutrient-poor Oxisol (lateritic soil) near San Carlos de Rio Negro, Venezuela, the average total above-ground dry weight of lianas was 15.7 t ha-I which was 4.5 percent of the estimated above-ground forest biomass. The average leaf area index of lianas was 1.2 M2 m-2 and constituted 19 percent of total forest leaf area. In comparison to trees, liana stems are small in diameter relative to the sizes of their crowns. This difference in allometry occurs because lianas rely on other plants for support and liana stems generally have large diameter and thus efficient xylem vessels. By maintaining the conducting capacity of their vessels for longer periods of time than do trees, lianas are able to increase further their leaf biomass-stem diameter ratios. Increases in cross sectional areas of liana stems are associated with proportionately larger increases in leaf biomass than comparable increases in cross sectional areas of tree stems. LIANAS ARE WOODY CLIMBING PLANTS that typically rely on other plants for mechanical support. They are often strikingly apparent in tropical forests (Spruce 1908, Richards 1952, Longman and Jenik 1974), but little quantitative information exists on liana abundance. The present study reports liana biomass and leaf area in a tierra firme (never flooded) forest in the Rio Negro Basin near San Carlos de Rio Negro, Venezuela; Jordan and Uhl (1978) gave estimates of tree biomass in the same area. Data from destructively sampled lianas are also used to examine quantitatively the relations between stem diameter, leaf biomass, and total above-ground biomass. STUDY SITE AND METHODS The study site was in the Territorio Amazonas, Venezuela near San Carlos de Rio Negro (1?56'N, 67?03'W) at an elevation of 119 m. This area receives an average of 3500 mm of rainfall per year and average monthly rainfall exceeds 100 mm even during the dry period (January through March; Heuveldop 1977). Sampling was conducted in evergreen forest growing on a nutrient impoverished Oxisol with slopes less than 5?. Charcoal fragments found in most soil samples (Stark and Spratt 1977) suggest a history of human use (i.e., possible clearing and burning), but there was no evidence of recent clearing. Uhl and Murphy (1981) point out that low soil fertility may be responsible for the low tree basal area (28 m2 ha-'), low canopy stature (tallest trees 25-30 m), and high density of stems (232 trees >20 cm dbh per ha). The average above-ground biomass (dry weight) of living trees in the study area was 335 t ha-1 (Jordan and Uhl 1978). Global surveys of forest biomass suggest an average for tropical forests of approximately 450 trha-' (Lieth 1975). Liana abundance and size-class distribution were estimated by species in 20 randomly located 100 m2 circular sample plots. In each plot I measured the dbh (diameter at 1.3 m or above the buttresses) of every tree and liana >2 m tall, determined the species of each liana, and recorded the sizes of the trees upon which the lianas grew. Lianas <2 m tall were identified, counted, and recorded as free standing (upright) or climbing. Only lianas rooted in the plots were enumerated. Many of the underground connections between stems had undoubtedly broken and decomposed. For this reason, an individual for the purposes of this study was considered to be an independently climbing or self-supporting stem. Plants in the Araceae were not included because many species are herbaceous and grow as epiphytes or hemiepiphytes (plants that either start out or end up their lives as epiphytes). Lianas for biomass determinations were selected to represent the range of observed diameters and included only the most common species. Large lianas often pass from canopy tree to canopy tree but, by climbing several times into the canopy and cutting supporting tree branches, it was possible to extract lianas from the tree tops. As a result, lianas harvested for biomass determination are reasonably complete. On the ground all the liana leaves were removed by hand and weighed on hanging scales. I randomly selected and weighed 50 leaves from every harvested liana for subsequent determination of wet-to-dry weight conversion factors; an additional 10 leaves were randomly selected from each liana for determination of area-weight relations. To estimate stem biomass, I cut up and weighed all the stems and branches and selected small (5-10 cm long) sections of representative diameters for weight and density determinations. I Present address: Department of Botany, University of Florida, Gainesville, Florida 32611, U.S.A. BIOTROPICA 15(3): 185-189 1983 185 This content downloaded from 157.55.39.118 on Fri, 22 Apr 2016 06:20:53 UTC All use subject to http://about.jstor.org/terms TABLE 1. Lianas used in biomass regressions.

Early Plant Succession after Cutting and Burning in the Upper Rio Negro Region of the Amazon Basin

(1) Changes in vegetation structure, species composition, and species dominance were studied over the first twenty-two months of succession after the cutting and burning of several mature tierra firme (i.e. non-flooded) forest sites in south Venezuela in the upper Rio Negro region of the Amazon Basin. To explain the observed succession, additional field investigations were undertaken. (2) Four months after burning the density of plants was less than 1 m-2. The density of successional woody plants, forbs, and grasses increased rapidly from the fourth to the tenth month of succession. There was little change in plant density between the tenth and twenty-second month, but a large change in vegetation height occurred during this time. By the twenty-second month a loose canopy of Cecropia spp. was present at 5 m height. (3) Many of the forest tree species sprouted from the stump when cut, but burning killed sprouts and significantly reduced the size of the seed bank. Nevertheless, the first successional woody colonizers established from seed which survived the burn. The first forb and grass colonizers established from seeds dispersed onto the site after the burn. (4) The common successional woody species had bator bird-dispersed seeds. Many forbs and grasses had wind-dispersed seeds. (5) Population densities were low during the first months of succession because of the low density of propagules and because the low rainfall during this time was not favourable for seedling germination or establishment. The rapid increase in plant density after about the fourth month occurred because the early colonizers had then begun to produce, and disperse locally, large numbers of seeds. (6) There were six distinct microhabitat types present on the sites after burning. Most species tested showed distinct microhabitat preferences.