scholarly journals Sensitivity of three tree ferns during their first phase of life to the variation of solar radiation and water availability in a Mexican cloud forest

2015 ◽  
Vol 102 (9) ◽  
pp. 1472-1481 ◽  
Author(s):  
Karolina Riaño ◽  
Oscar Briones
Keyword(s):  
Solar Radiation ◽  
Water Availability ◽  
Cloud Forest ◽  
Tree Ferns

Host preferences of low-trunk vascular epiphytes in a cloud forest of Veracruz, Mexico

2005 ◽  
Vol 21 (6) ◽  
pp. 651-660 ◽  
Author(s):  
Klaus Mehltreter ◽  
Alejandro Flores-Palacios ◽  
José G. García-Franco
Keyword(s):  
Water Retention ◽  
Cloud Forest ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Host Preferences ◽  
Host Group ◽  
Vascular Epiphytes ◽  
Lower Trunk ◽  
Tree Ferns ◽  
Epiphyte Species

The diversity, abundance and frequency of vascular epiphytes on the lower trunk were compared between two host groups of a Mexican cloud forest: angiosperm trees (n = 72) and tree ferns (n = 28). The bark of the five most frequent host trees and the root mantle of the two tree ferns were analysed for their thickness, water content, water retention capacity and pH. A total of 55 epiphyte species and 910 individuals were found on the 27 host species. On hosts with a dbh range of 5–10 cm, epiphytes were significantly more diverse (4.3±0.9 species per host) and more abundant (12.5±2.2 individuals per host) on tree ferns than on angiosperm trees (1.9±0.2 species per host and 3.9±0.6 individuals per host). However, these differences were not significant for the dbh class of 10–20 cm, because epiphyte numbers increased on angiosperm trees with larger host size, but not in tree ferns. Most epiphyte species had no preference for any host group, but four species were significantly more frequent on tree ferns and two species on angiosperm trees. The higher epiphyte diversity and abundance on tree fern trunks of the smallest dbh class is attributed to their presumably greater age and to two stem characteristics, which differed significantly between host groups, the thicker root mantle and higher water retention capacity of tree ferns. These bark characteristics may favour germination and establishment of epiphytes.

scholarly journals Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

2010 ◽  
Vol 45 (12) ◽  
pp. 1331-1341 ◽  
Author(s):  
Homero Bergamaschi ◽  
Genei Antonio Dalmago ◽  
João Ito Bergonci ◽  
Cleusa Adriane Menegassi Bianchi Krüger ◽  
Bruna Maria Machado Heckler ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Leaf Area Index ◽  
Extinction Coefficient ◽  
Water Availability ◽  
Conventional Tillage ◽  
No Tillage ◽  
Tillage Systems ◽  
Area Index ◽  
Tillage System ◽  
Crop Cycle

The objective of this work was to evaluate changes in the photosynthetic photon flux density (PPFD) interception efficiency and PPFD extinction coefficient for maize crop subjected to different soil tillage systems and water availability levels. Crops were subjected to no-tillage and conventional tillage systems combined with full irrigation and non-irrigation treatments. Continuous measurements of transmitted PPFD on the soil surface and incoming PPFD over the canopy were taken throughout the crop cycle. Leaf area index and soil water potential were also measured during the whole period. Considering a mean value over the maize cycle, intercepted PPFD was higher in the conventional tillage than in the no-tillage system. During the initial stages of plants, intercepted PPFD in the conventional tillage was double the PPFD interception in the no-tillage treatment. However, those differences were reduced up to the maximum leaf area index, close to tasseling stage. The lowest interception of PPFD occurred in the conventional tillage during the reproductive period, as leaf senescence progressed. Over the entire crop cycle, the interception of PPFD by the non-irrigated plants was about 20% lower than by the irrigated plants. The no-tillage system reduced the extinction coefficient for PPFD, which may have allowed a higher penetration of solar radiation into the canopy

scholarly journals Historical reconstruction of climatic and elevation preferences and the evolution of cloud forest-adapted tree ferns in Mesoamerica

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2696 ◽  
Author(s):  
Victoria Sosa ◽  
Juan Francisco Ornelas ◽  
Santiago Ramírez-Barahona ◽  
Etelvina Gándara
Keyword(s):  
Cloud Forest ◽  
Phylogenetic Analyses ◽  
Divergence Time ◽  
Phenotypic Traits ◽  
Cloud Forests ◽  
Altitudinal Distribution ◽  
Ancestral Area ◽  
Divergence Time Estimates ◽  
Tree Ferns ◽  
Extant Species

BackgroundCloud forests, characterized by a persistent, frequent or seasonal low-level cloud cover and fragmented distribution, are one of the most threatened habitats, especially in the Neotropics. Tree ferns are among the most conspicuous elements in these forests, and ferns are restricted to regions in which minimum temperatures rarely drop below freezing and rainfall is high and evenly distributed around the year. Current phylogeographic data suggest that some of the cloud forest-adapted species remainedin situor expanded to the lowlands during glacial cycles and contracted allopatrically during the interglacials. Although the observed genetic signals of population size changes of cloud forest-adapted species including tree ferns correspond to predicted changes by Pleistocene climate change dynamics, the observed patterns of intraspecific lineage divergence showed temporal incongruence.MethodsHere we combined phylogenetic analyses, ancestral area reconstruction, and divergence time estimates with climatic and altitudinal data (environmental space) for phenotypic traits of tree fern species to make inferences about evolutionary processes in deep time. We used phylogenetic Bayesian inference and geographic and altitudinal distribution of tree ferns to investigate ancestral area and elevation and environmental preferences of Mesoamerican tree ferns. The phylogeny was then used to estimate divergence times and ask whether the ancestral area and elevation and environmental shifts were linked to climatic events and historical climatic preferences.ResultsBayesian trees retrievedCyathea, Alsophyla, GymnosphaeraandSphaeropterisin monophyletic clades. Splits for species in these genera found in Mesoamerican cloud forests are recent, from the Neogene to the Quaternary, Australia was identified as the ancestral area for the clades of these genera, except forGymnosphaerathat was Mesoamerica. Climate tolerance was not divergent from hypothesized ancestors for the most significant variables or elevation. For elevational shifts, we found repeated change from low to high elevations.ConclusionsOur data suggest that representatives of Cyatheaceae main lineages migrated from Australia to Mesoamerican cloud forests in different times and have persisted in these environmentally unstable areas but extant species diverged recentrly from their ancestors.

Trait variation of a generalist tree species (Eremanthus erythropappus, Asteraceae) in two adjacent mountain habitats: savanna and cloud forest

2018 ◽  
Vol 66 (8) ◽  
pp. 640 ◽  
Author(s):  
Erica Rievrs Borges ◽  
Jamir Prado-Junior ◽  
Lucas Deziderio Santana ◽  
Camila Nardy Delgado ◽  
Diego Raymundo ◽  
...  
Keyword(s):  
Leaf Area ◽  
Water Availability ◽  
Tree Species ◽  
Cloud Forest ◽  
Functional Trait ◽  
Generalist Species ◽  
Mountain Habitats ◽  
Canopy Area ◽  
Wind Exposure ◽  
Architectural Traits

Cloud forests and savannas differ in several environmental aspects, particularly in light irradiance and water availability. Such differences can be selective for specific sets of leaves and architectural strategies to capture light and use water. In the present study we evaluated functional traits variation in a generalist species in two adjacent habitats experiencing an abrupt change in resource availability (light and water availability). We collected several leaf, stem and architectural traits of the tree species Eremanthus erythropappus (DC.) MacLeish in shrubland savanna (habitat facing higher drought stress and wind exposure) and cloud forest (shaded environment). Trees in the shrubland savanna exhibited functional trait values that enhance drought tolerance (i.e. higher wood density and leaf thickness) whereas trees in the cloud forest exhibited functional trait values that enhance light capture (i.e. taller individuals with higher leaf area and specific leaf area). Additionally, the individuals in the shrubland savanna had wider and deeper crowns, pointing that the benefits of a larger canopy area to capture light during the day and humidity from condensation at night exceed the higher risk of mechanical damage by falling debris due to high wind exposure. For all traits, variation among the individuals was lower than variation among habitats. Our results indicate the strong role of the environment as a driver of intraspecific variation and that architectural traits (usually poorly studied compared with other traits) should be included as an important parameter of variation in functional analyses when evaluating the effect of environmental conditions on tree performance.

Epiphyte assemblages respond to host life-form independently of variation in microclimate in lower montane cloud forest in Panama

2014 ◽  
Vol 30 (6) ◽  
pp. 625-628 ◽  
Author(s):  
Jennifer C. Sanger ◽  
James B. Kirkpatrick
Keyword(s):  
Species Richness ◽  
Life Form ◽  
Cloud Forest ◽  
Light Level ◽  
Montane Forest ◽  
Vascular Epiphytes ◽  
Montane Cloud Forest ◽  
Tree Ferns ◽  
Host Life ◽  
Light Profiles

Abstract:We investigated the effects of host tree on epiphyte diversity, controlling for microclimate. We measured the light profiles of the lower trunks of 20 individuals, each from three host groups (tree ferns, dicots, palms) occupying the understorey in a tropical montane forest in Panama. The per cent cover and species richness of vascular and non-vascular epiphytes were surveyed on the lower trunks of each understorey host. Light varied considerably between trees (5–21% total transmitted light) but mean light level did not vary between types of host. Light was not significant as a covariate with host in any model. Tree ferns had higher covers than dicots and palms of filmy ferns (15%, 0.02% and 0.2%), other ferns (7%, 0% and 0.5%) and other vascular epiphytes (16%, 3% and 3.4%), and greater species richness of vascular epiphytes (filmy ferns: 3, 0.4 and 0.5; other ferns: 2, 0.2 and 0; other vascular: 7, 2 and 2). Dicots had a higher cover of liverworts (53%) than palms (18%) and tree ferns (27%). Palms and tree ferns were the compositional extremes. We conclude that the differences in species composition and cover between the three host groups relate better to physical differences between hosts than differences in light climate.

scholarly journals Examination of evaporative fraction diurnal behaviour using a soil-vegetation model coupled with a mixed-layer model

1999 ◽  
Vol 3 (2) ◽  
pp. 259-270 ◽  
Author(s):  
J.-P. Lhomme ◽  
E. Elguero
Keyword(s):  
Solar Radiation ◽  
Soil Water ◽  
Wind Velocity ◽  
Mixed Layer ◽  
Water Availability ◽  
Layer Model ◽  
Evaporative Fraction ◽  
Saturation Deficit ◽  
Available Energy ◽  
Diurnal Course

Abstract. In many experimental conditions, the evaporative fraction, defined as the ratio between evaporation and available energy, has been found stable during daylight hours. This constancy is investigated over fully covering vegetation by means of a land surface scheme coupled with a mixed-layer model, which accounts for entrainment of overlying air. The evaporation rate follows the Penman-Monteith equation and the surface resistance is given by a Jarvis type parameterization involving solar radiation, saturation deficit and leaf water potential. The diurnal course of the evaporative fraction is examined, together with the influence of environmental factors (soil water availability, solar radiation input, wind velocity, saturation deficit above the well-mixed layer). In conditions of fair weather, the curves representing the diurnal course of the evaporative fraction have a typical concave-up shape. Around midday (solar time) these curves appear as relatively constant, but always lower that the daytime mean value. Evaporative fraction decreases when soil water decreases or when solar energy increases. An increment of saturation deficit above the mixed-layer provokes only a slight increase of evaporative fraction, and wind velocity has almost no effect. The possibility of estimation daytime evaporation from daytime available energy multiplied by the evaporative fraction at a single time of the day is also investigated. It appears that it is possible to obtain fairly good estimates of daytime evaporation by choosing adequately the time of the measurement of the evaporative fraction. The central hours of the day, and preferably about 3 hr before or after noon, are the most appropriate to provide good estimates. The estimation appears also to be much better when soil water availability (or evaporation) is high than when it is low.

Distribution of Tree Ferns (Cyatheaceae) across the Successional Mosaic in an Andean Cloud Forest, Narino, Colombia

1998 ◽  
Vol 88 (2) ◽  
pp. 60 ◽  
Author(s):  
Nan Crystal Arens ◽  
Patricia Sanchez Baracaldo
Keyword(s):  
Cloud Forest ◽  
Tree Ferns

Report Details Solar Radiation Alert and Recommendations

Space Weather ◽  
2006 ◽  
Vol 4 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Tracy Staedter
Keyword(s):  
Solar Radiation
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