The penetration of solar erythemal ultraviolet radiation has been measured in the shade of a gum (Eucalyptus sp.) and a she oak (Casaurina) tree, both on a horizontal plane and with polysulphone dosimeters to human anatomical sites. This has provided new data useful for protection strategies against harmful ultraviolet radiation. For larger solar zenith angles, the relative penetration of solar...

The fraction and the distribution of the personal daily solar erythemal UV exposure were assessed for the shade provided by Australian gum trees in each of the four seasons to allow evaluation of the reduction in the personal UV exposure in tree shade over a year. The personal annual erythemal UV exposures in the tree shade ranged from 2,510 SED (Standard Erythema Dose) for the vertical part of...

Light-related plasticity of crown morphology and within-crown characteristics were investigated in understory sun and shade saplings of three codominant subalpine conifers, Abies mariesii M.T. Mast., Abies veitchii Lindl. and Picea jezoensis var. hondoensis (Mayr) Rehd. Compared with those of sun saplings, current-year shoots of shade saplings allocated less biomass to needles, resulting in les...

PREMISE OF THE STUDY California chaparral shrub species have different life history types: Nonsprouters (NS) are killed by fire and persist through a fire-stimulated seed bank; facultative sprouters (FS) reestablish by a combination of vegetative sprouting and seeding; and obligate sprouters (OS) reestablish exclusively by sprouting. Nonsprouters and FS establish seedlings in open-canopy postfi...

Determining the permeability of different types of landscape matrices to animal movement is essential for conserving populations in fragmented landscapes. We evaluated the effects of habitat patch size and matrix type on diversity, isolation, and dispersal of ithomiine butterflies in forest fragments surrounded by coffee agroecosystems in the Colombian Andes. Because ithomiines prefer a shaded ...

We studied the physiological differences between sun and shade seedlings of Rhizhophora mangle, the red mangrove. Using the seedlings and their leaves, five experiments were made to determine whether true adaptations were available to shade seedlings to cope with higher stress. The reason why the shade seedlings were in higher stress is because they have to deal with the salt and intense compet...

many parameters affect essential oil yield and chemical composition of aromatic plants. for obtaining the highest quantity and quality of essential oil, it is necessary to know the proper methods of drying and distillation. the aim of this research was to investigate the influence of drying and extraction methods on the yield and chemical composition of the essential oil of eucalyptus sargentii...

The ability to down-regulate leaf maximum net photosynthetic capacity (Amax) and dark respiration rate (Rdark) in response to shading is thought to be an important adaptation of trees to the wide range of light environments that they are exposed to across space and time. A simple, general rule that accurately described this down-regulation would improve carbon cycle models and enhance our under...

We examined the effects of elevated CO2 concentration ([CO2]) on leaf demography, late-season photosynthesis and leaf N resorption of overstory sweetgum (Liquidambar styraciflua L.) trees in the Duke Forest Free Air CO2 Enrichment (FACE) experiment. Sun and shade leaves were subdivided into early leaves (formed in the overwintering bud) and late leaves (formed during the growing season). Overal...

The consequences of light adaptation and acclimation of photosynthesis on photosynthetic nitrogen use efficiency (NUE), particularly as it relates to the efficiency of ribulose-1,5-bisphosphate carboxylase (Rubisco) use in photosynthetic CO2 assimilation, was studied in the sun species Glycine max and the shade species Alocasia macrorrhiza. Both G. max and A. macrorrhiza were found to possess t...