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Liana Density (liana + density)

Distribution by Scientific Domains

Life Sciences	85%

Selected Abstracts

Annual Rainfall and Seasonality Predict Pan-tropical Patterns of Liana Density and Basal Area

BIOTROPICA, Issue 3 2010
Saara J. DeWalt
ABSTRACT We test the hypotheses proposed by Gentry and Schnitzer that liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of liana abundance based on a different dataset. We compiled a pan-tropical dataset containing 28,953 lianas (,2.5 cm diam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall <100 mm) represented by these datasets were 860,7250 mm/yr and 0,7 mo, respectively. Pan-tropically, liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source]

Landscape context and microenvironment influences on liana communities within treefall gaps

JOURNAL OF VEGETATION SCIENCE, Issue 5 2008
Agustina Malizia
Abstract Questions: How do gap aspect, openness, age and gap density in the surroundings affect diversity and composition of lianas within treefall gaps? Are the variation patterns in liana communities within treefall gaps associated with their climbing mechanisms? Location: Subtropical montane forests in northwestern Argentina. Methods: We used ordination analyses (NMDS) and multiple regressions to describe liana communities (species and climbing groups, stems , 1 cm) in 35 gaps located in a 6-ha plot and to assess relationships with aspect, canopy and subcanopy openness, age and density of recent (three to eight years old) and old (> 8 years old) gaps. Results: Treefall gaps segregated in the ordination diagrams based on their liana species and climbing mechanisms composition: gaps surrounded by a higher density of recent gaps showed higher densities of lianas species using tendrils, spines/hooks and voluble stems. Liana density and richness (independent of stem density) were also positively associated with the density of recent gaps in the surroundings, and negatively associated to gap age. The number of liana species corrected per area was negatively associated to gap aspect and subcanopy openness, and absolute number of liana species was positively associated to gap canopy openness. Conclusions: This study integrates the analysis of different factors influencing liana communities within treefall gaps, and shows that spatial context of gap density (a variable largely neglected in previous studies) is particularly important on lianas composition and diversity, probably by increasing propagule input and the availability of small trellises for support. [source]

Testing liana cutting and controlled burning as silvicultural treatments for a logged forest in the eastern Amazon

JOURNAL OF APPLIED ECOLOGY, Issue 6 2001
Jeffrey J. Gerwing
Summary 1In the eastern Brazilian Amazon, logged forests frequently include patches where liana density is particularly high. In these so-called liana tangles, competition from lianas is predicted to reduce tree growth significantly, thus effectively impeding future timber production. To begin to develop a silvicultural strategy for these patches, the impact of liana cutting and controlled burning on liana density, tree growth and tree regeneration in liana-dominated patches was investigated in a logged forest in the eastern Brazilian Amazon. 2The two treatments (liana cutting and controlled burning) and a control were installed in 40 × 40-m plots in a randomized complete block design of six blocks. Treatments were conducted during October 1997, and tree diameter growth and mortality, canopy cover, regeneration and liana density were monitored over 2 years. 3Mean mortality following burning was significantly higher for lianas (79%) than for trees (48%), as was the mean coppicing rate of top-killed stems (42% for lianas vs. 20% for trees). Coppicing combined with some recruitment from seed resulted in liana densities in the burned plots returning to 70% of the values in the control plots only 2 years post-treatment. 4Canopy light transmittance, estimated from hemispherical canopy photographs taken at 1 m above the ground, increased significantly from c. 4% in controls to 8% in cut and 12% in burned treatments, and these differences persisted over the 2-year study period. 5In the absence of silvicultural intervention, mean tree diameter increments were low (1·3 mm year,1), suggesting that the successional transition to higher stature forest was occurring very slowly. Each of the treatments resulted in a more than doubling of mean annual tree growth (3 and 2·8 mm year,1 for liana-cut and burned treatments, respectively). The treatments also significantly reduced the occurrence of trees that showed no growth over the study period, from 56% in controls to 30% in cut and 32% in burned treatments. 6The results of this study suggest that although burning resulted in increased tree growth, rapid recolonization of surviving trees by lianas and the high vulnerability of burned stands to unwanted repeat burns are likely to cancel out any of the possible benefits of controlled burning as a silvicultural treatment for liana-dominated patches. Liana cutting, on the other hand, showed promise and its adoption as part of a larger strategy for the recuperation of the timber production potential of logged tropical forests seems warranted. [source]

Annual Rainfall and Seasonality Predict Pan-tropical Patterns of Liana Density and Basal Area

Structure and Biomass of Four Lowland Neotropical Forests

BIOTROPICA, Issue 1 2004
Saara J. DeWalt
ABSTRACT 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 serra 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). RESUMEN Contrastamos la estructura y la biomasa de cuatro bosques de bajura Neotropicales (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 contributión 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 pequena 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 cuanti-tativas (por ejemplo, riqueza de especies). [source]