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Aim: Lianas are an important component of forest structure in the tropics, accounting for up to 45% of total stems. Mounting evidence that tropical forests are undergoing structural changes, with a growing abundance of lianas reducing forest carbon storage potential, imparts a sense of urgency to study the drivers that control liana abundance and biomass, particularly in Africa where data come from a few, small-scale studies. Location: Gabon, Africa. Methods: In the first countrywide study of lianas, we implemented the most ambitious, large-scale forest inventory in tropical Africa to date, quantifying the density, basal area and biomass of large lianas (≥10 cm in diameter) using a systematic, random design of 104 plots located across Gabon. Additionally, we examined the relative importance of environmental variables (mean annual precipitation, mean annual temperature, seasonality, soil nitrogen, soil fertility), disturbance (effect of gaps, forest type) and forest structure (large tree biomass) in driving macroscale variation in the abundance of large lianas. Results: In total, we surveyed 1354 large lianas, and found the density, basal area and biomass of large lianas in Gabon to be comparable to that in other tropical forests. The success of large lianas was positively related to soil N, but most strongly correlated with forest structure, particularly large tree biomass. The strength of the association between large lianas and large trees increased with tree size class. Main conclusions: Forest structure and the availability of large trees may be more important predictors of the abundance and distribution of large lianas in African tropical forests than environmental variables and disturbance. Changing environmental conditions are likely to have little direct effect on large lianas, but climate change, defaunation and land-use activities that diminish forest structure and reduce the number of large trees could have strong indirect effects on large lianas in Central African forests.

Habitat fragmentation affects aboveground biomass in Amazonian forests, with potentially important implications for carbon storage and greenhouse gas emissions. We assessed the dynamics of aboveground-biomass stocks by combining long-term (10-19 yr) data on mortality, damage, growth, and recruitment of large (≥10 cm diameter at breast height [dbh]) trees with measurements of nearly all other live and dead plant material (seedlings, saplings, small trees, palms, lianas, downed wood debris, snags, litter) in 50 1-ha plots in fragmented and continuous Amazonian forests. The key process altering biomass dynamics in fragmented forests is the chronically elevated mortality of large trees, which apparently results from microclimatic changes and increased wind turbulence near forest edges. This, in turn, accelerates the production of necromass and leads to significantly increased wood debris and litter on the forest floor. Near forest edges, frequent canopy disturbance increases the amount of light in the understory, resulting in accelerated tree recruitment, significantly higher biomass of small (5-10 cm dbh) trees, and higher liana densities. Surprisingly, the estimated annual turnover of wood debris increases significantly near forest edges, suggesting that decomposition is occurring more rapidly in fragmented than continuous forests. These results reveal that habitat fragmentation fundamentally alters the distribution and dynamics of aboveground biomass in Amazonian forests. The rate of carbon cycling probably increases sharply, both because long-lived canopy and emergent trees decline in favor of shorter-lived successional trees and lianas, and because necromass production and turnover both appear to increase. Carbon storage in live vegetation also declines because small successional trees and lianas (which typically have low wood density) store substantially less carbon than do large, old-growth trees. Finally, the decline and rapid decay of live biomass in forest fragments may produce substantial atmospheric carbon emissions, above and beyond that resulting from deforestation per se.

The plant vigour hypothesis proposes that herbivores should favour feeding on more vigorously growing plants or plant modules. Similarly, we would expect herbivores to favour plants that regrow vigorously after herbivory. Larger animals, like elephants, may also select plant species relative to their availability and prefer species with larger growth forms in order to meet their intake requirements. The food preferences of the Bornean elephant (Elephas maximus borneensis) in the Lower Kinabatangan Wildlife Sanctuary, Sabah, Malaysia, were investigated along 12 transects in areas where elephants were recently sighted feeding. One hundred and eighty-two plants were eaten and 185 plants were measured for species availability along transects. Species vigour was determined by the monthly regrowth in new shoot length after elephant feeding and the number of new shoots produced on each plant. Measurements were carried out on each plant for 9 mo or until the new shoot was eaten. Plant sizes were determined from their basal diameter. The Bornean elephant did not prefer more vigorous species or species with larger growth forms. New shoots did not grow longer on preferred than avoided species. Additionally, unlike other elephants that live in a forest environment, the Bornean elephant preferred species from the Poaceae (specifically Phragmites karka and Dinochloa scabrida) over other plant types including gingers, palms, lianas and woody trees.

We contrasted the structure and biomass of four lowland Neotropical forests (La Selva, Costa Rica; Barro Colorado Island, Panama; Cocha Cashu, Peru; and KM41, Brazil) to determine if commonalities exist within and among forests differing in latitude, rainfall, seasonality, and soil fertility. We examined the effect of soil fertility specifically by measuring the density and basal area of trees, lianas, and palms on two soil types differing in fertility at each site. We used allometric relationships to estimate the contribution of the various life-forms to total aboveground biomass (AGB) and compared two relationships for trees 30 cm diameter or greater. Estimated liana density and AGB were similar among sites, but the density and AGB of trees and palms, estimated using diameter alone, differed significantly. Basal area and AGB of trees 10 cm diameter at breast height (DBH) or greater differed among forests and averaged 30.2 m2/ha and 250 Mg/ha, respectively. Cocha Cashu and KM41 had higher tree basal area and AGB than La Selva or Barro Colorado Island. Across forests, lianas and small trees (1—10 cm DBH) each contributed between 4 and 5 percent of the total AGB and small palms contributed ca 1 percent. Many forest inventories ignore lianas, as well as trees and palms less than 10 cm DBH, and therefore underestimate AGB by ca 10 percent. Soil type had little influence on the forest structure within sites, except at Cocha Cashu where total AGB was much higher and liana density much lower on the more fertile old floodplain Entisols than the terra firme Oxisols. Although total stem density, basal area, and some biomass components differed significantly among forests, they seemed less variable than other quantitative measures (e.g., species richness). /// Contrastamos la estructura y la biomasa de cuatro bosques de bajura Neo tropicales (La Selva, Costa Rica; Isla Barro Colorado, Panamá; Cocha Cashu, Perú; y KM41, Brasil) para determinar si existen patrones comunes entre bosques que difieren en la latitud, en la lluvia total, en la estacionalidad, y en la fertilidad de suelo. Examinamos el efecto de la fertilidad de suelo en cada sitio específicamente midiendo el área basal y densidad de árboles, lianas, y palmas en dos tipos de suelo que difieren en fertilidad. Usamos ecuaciones alométricas para estimar la contribución relativa de las varias formas de vida a la biomasa aérea (AGB) y comparamos dos ecuaciones para estimar biomasa con base en árboles ≥ 30 cm diámetro. La densidad y AGB estimada de lianas fueron similares entre sitios, pero la densidad y AGB de árboles y palmas estimada en base solamente a diámetros fueron significativamente distintas. El área basal y la AGB de árboles ≥ 10 cm diámetro a la altura de pecho (DAP) difirieron entre bosques y promediaron 30.2 m2/ ha y 250 Mg/ha. En Cocha Cashu y KM41 observamos mayor área basal y AGB para árboles que en La Selva o la Isla Barro Colorado. En general lianas y árboles pequeños (1-10 cm DAP) contribuyeron entre 4-5 porciento del AGB total cada uno y palmas pequeñas contribuyeron alrededor de 1 porciento. Muchos inventarios del bosque ignoran tanto las lianas como los árboles y palmas < 10 cm DAP y por lo tanto subestiman AGB en alrededor de un 10 porciento. El tipo del suelo mostró una influencia pequeña en la estructura del bosque dentro de sitios, menos en Cocha Cashu donde AGB total fue mucho más alto y densidad de lianas y palmas fue más bajo en los Entisols de mayor fertilidad que los Ultisols de menor fertilidad. Aunque la densidad de tallos, área basal, y algunos componentes de la biomasa difirieron significativamente entre bosques, estos parecieron menos variables que otras medidas cuantitativas (por ejemplo, riqueza de especies).

We contrasted the structure and biomass of four lowland Neotropical forests (La Selva, Costa Rica; Barro Colorado Island, Panama; Cocha Cashu, Peru; and KM41, Brazil) to determine if commonalities exist within and among forests differing in latitude, rainfall, seasonality, and soil fertility. We examined the effect of soil fertility specifically by measuring the density and basal area of trees, lianas, and palms on two soil types differing in fertility at each site. We used allometric relationships to estimate the contribution of the various life-forms to total aboveground biomass (AGB) and compared two relationships for trees 30 cm diameter or greater. Estimated liana density and AGB were similar among sites, but the density and AGB of trees and palms, estimated using diameter alone, differed significantly. Basal area and AGB of trees 10 cm diameter at breast height (DBH) or greater differed among forests and averaged 30.2 m2/ha and 250 Mg/ha, respectively. Cocha Cashu and KM41 had higher tree basal area and AGB than La Selva or Barro Colorado Island. Across forests, lianas and small trees (1–10 cm DBH) each contributed between 4 and 5 percent of the total AGB and small palms contributed ca 1 percent. Many forest inventories ignore lianas, as well as trees and palms less than 10 cm DBH, and therefore underestimate AGB by ca 10 percent. Soil type had little influence on the forest structure within sites, except at Cocha Cashu where total AGB was much higher and liana density much lower on the more fertile old floodplain Entisols than the terra firme Oxisols. Although total stem density, basal area, and some biomass components differed significantly among forests, they seemed less variable than other quantitative measures (e.g., species richness).

Understanding how biodiversity persists in the small fragments of forest that remain in many tropical regions is a vital priority. This chapter reviews available studies on liana communities and liana–tree interactions in fragmented tropical forests. Although much remains unknown, it is apparent that lianas often increase dramatically in abundance in fragmented forests. Fragmentation of once‐continuous primary forests results in a considerable increase in landscape‐wide liana abundance and rates of tree infestation. There are three main reasons for the increase in liana abundance. First, the area of forest edge greatly increases within fragmented forest landscapes and forest edges are preferential liana habitat. Second, elevated rates of large tree mortality, turnover and treefall‐gap creation occur in many forest fragments, which again enhance the amount of available disturbed and well‐lit habitat preferred by lianas. Finally, initial forest loss and fragmentation may lead to a greater area of forest regeneration (“younger” forest).