Although snags and coarse woody debris are a small component of ecosystem respiration, disturbances can significantly increase the mass and respiration from these carbon (C) pools. The objectives of this study were to (1) measure respiration rates of snags and coarse woody debris throughout the year in a forest previously defoliated by gypsy moths, (2) develop models for dead stem respiration r...

The foliage status in the main stem of Scots pines (Pinus sylvestris) was studied retrospectively using the needle trace method (NTM) on a stand, seriously defoliated by the pine sawfly (Diprion pini) in the 1980s. Needle density increased abruptly in the seasons following the defoliation. The strongest reduction in annual needle production occurred one year later. As a consequence of lower nee...

Snow ablation modelling at the stand scale must account for the variability in snow cover and the large variations of components of energy transfer at the forest ̄oor. Our previous work successfully predicted snow ablation in a mature jack pine stand by using a one-dimensional snow process model and models predicting radiation below forest canopies. This work represents a second test of our bas...

The cloning of two highly homologous chicory (Cichorium intybus var. foliosum cv Flash) fructan 1-exohydrolase cDNAs (1-FEH IIa and 1-FEH IIb) is described. Both isoenzymes could be purified from forced chicory roots as well as from the etiolated "Belgian endive" leaves where the 1-FEH IIa isoform is present in higher concentrations. Full-length cDNAs were obtained by a combination of reverse t...

The role of roots in the enhancement of cytokinin content and leaf growth of Phaseolus vulgaris plants after decapitation and partial defoliation was investigated. Partial excision of the roots of plants which were decapitated above the primary leaf node resulted in a reduction of leaf growth and soluble proteins accumulation in the primary leaves. Roots excision was done at time of decapitatio...

A field experiment and a laboratory experiment were conducted in 2011 to determine the effect of intensity of defoliation on yield of maize (Zea mays). The field experiment included seven defoliation intensities (0, 2, 4, 6, 8, 10 and whole leaves per plant) from top to bottom leaves. Seeds of the field experiment were used for the laboratory experiment. In the laboratory experiment, germinatio...

Remobilization of internal resources is an important mechanism enabling plants to be partly independent of external nutrient availability. We assessed resource remobilization during the growing period in woody and foliar tissues of leafy branches of mature evergreen Mediterranean oak (Quercus ilex L.) at three field sites. We compared nonstructural carbohydrates, lipids, nitrogen and phosphorus...

Lycium chilense, a deciduous perennial shrub, is one of the endangered native species of Patagonia due to sheep overgrazing. Chances of recolonization by seeds are scarce due to the limited density of propagules in the soil and very specific requirements for germination. The objective was to develop an in vitro propagation protocol that would help to perform reestablishment of this species in d...

It has been found that floral induced stems of flowering tobacco (Nicotiana tabacum cv. Wis. 38) plants contain large amounts of rapidly renaturing DNA, whereas noninduced stems of vegetative plants contain only small amounts. In addition, it has been shown that the striking qualitative difference in DNA between stems of flowering and vegetative plants mimics the over-all quantitative differenc...

We investigated whether development of resistance to a Bt crop in the presence of a natural enemy would be slower than without the natural enemy and whether biological control, in conjunction with a Bt crop, could effectively suppress the pest population. Additionally, we investigated whether insecticide-sprayed refuges of non-Bt crops would delay or accelerate resistance to the Bt crop. We use...