It has been hypothesized that slow-growing plants are more likely to maximize above-ground biomass and fitness when defoliated by herbivores than those with an already high relative growth rate (RGR). Some populations of the annual herb Datura stramonium L. can tolerate foliar damage better than others. The physiological basis of this difference is examined here in a comparative study of two ec...

Iron absorption studies with oral 59FeSO4 2.2% respectively) . Compared with the were performed on 13 iron-depleted, 1 1 normal controls, iron was decreased in iron-loaded, and 10 control rats, and nonthe epithelial cells of the iron-defIcient heme iron was determined in both isogroup, whereas higher concentrations lated epithelial cells and defoliated muwere observed in the defoliated mucosa c...

Drought-related tree die-off episodes have been observed in all vegetated continents. Despite much research effort, however, the multiple interactions between carbon starvation, hydraulic failure and biotic agents in driving tree mortality under field conditions are still not well understood. We analysed the seasonal variability of non-structural carbohydrates (NSCs) in four organs (leaves, bra...

A quantitative human dietary risk assessment was conducted using the glycoalkaloid concentrations measured from tubers of plants defoliated by Colorado potato beetles and undefoliated (control). There was a significantly greater production of glycoalkaloids for defoliated plants compared to control plants for both skin and inner tissue of tubers. The dietary risk posed to different human subgro...

We examined the effects of fertilization and gypsy moth defoliation on condensed tannin concentration (%CT) of hybrid poplar (Populus x canadensis cv 'Eugeneii') fine roots in the summers of 1997 and 1998. This factorial experiment included two defoliation treatments (defoliated and a foliated control) and fertilization treatments (100 kg nitrogen (N) ha(-1) and an unfertilized control). Gypsy ...

Recovery following defoliation can be modified by co-occurring site resource limitations. The growth response of young Eucalyptus globulus saplings to two defoliation events was examined in an experimental plantation with combinations of low (-) or high (+) water (W) and nitrogen (N) resources. Artificial defoliation was applied at 3 and 9 months of age to remove ~40 and 55% of leaf area in the...

The main objective of this thesis was to examine the effects of climate change and simulated herbivory (artificial foliage damage) on growth responses and leaf characteristics (chemical and morphological structure and consequent palatability) of silver birch (Betula pendula) seedlings. In order to achieve this target, seedlings were grown in climate controlled closed-top chambers under ambient ...

Phenolic compounds often accumulate in foliar tissues of deciduous woody plants in response to previous insect defoliation, but similar responses have been observed infrequently in evergreen conifers. We studied the effects of defoliation on the foliar chemistry of Scots pine (Pinus sylvestris L.) and cocoon mass, and survival of the pine sawfly (Diprion pini L.). In two successive years, needl...

BACKGROUND AND AIMS There is a growing concern about how forests will respond to increased herbivory associated with climate change. Carbon (C) and nitrogen (N) limitation are hypothesized to cause decreasing growth after defoliation, and eventually mortality. This study examines the effects of a natural and massive defoliation by an insect on mature trees' C and N storage, which have rarely be...

In closed-canopy forests, gap formation and closure are thought to be major drivers of forest dynamics. Crown defoliation by insects, however, may also influence understory resource levels and thus forest dynamics. We evaluate the effect of a forest tent caterpillar outbreak on understory light availability, soil nutrient levels and tree seedling height growth in six sites with contrasting leve...