Treesearch

The effect of elevated CO2 on the response of pitch pine (Pinus rigida) to aluminum was determined in three experiments with different nutrient levels.

We tested the hypothesis that temperature during gametogenesis and embryogenesis can affect progeny genotype and phenotype. Identical crosses were made among cloned parents of Larix spp. inside and outside a greenhouse, where the temperature inside averaged 4?C above the outside temperature. Significant growth differences as a function of crossing environment were observed. When the crosses were grown in the same environment the phenotypes of crosses made inside tended to resemble more southern ecotypes. In addition, segregation distortion at the chlorophyll- a/b-protein locus as a...

Increasing atmospheric concentrations of ozone and CO2 affect many aspects of tree physiology. However, their effects on tree resistance to insects have received relatively little attention. The objectives of this study were to test the effects of elevated CO2 and ozone on the resistance of three quaking aspen (Populus tremuloides) clones (216, 259, and 271) to first and fourth instars of four Lepidoptera species: gypsy moth (Lymantria dispar), forest tent caterpillar (Malacosoma disstria), large aspen tortrix (Choristoneura confictana), and whitemarked tussock moth (Orgyia leucostigma)....

We tested the effects of elevated CO2 and ozone on concentrations of the phenolic glycosides salicortin and tremulacin in immature and mature foliage of the trembling aspen (Populus tremuloides) clones 216, 259, and 271.

In response to increasing carbon dioxide levels, most general circulation models (GCMs) predict increasing temperatures and decreasing precipitation for the central hardwood region of the United States. Plants in this region will need to adapt to these changes as well as to other stress agents if they are to germinate, grow, and reproduce. For the last five years, our research program under the global change initiative has been designed to increase our understanding of the physiological and genetic mechanisms used by plants to respond and adapt to multiple stresses in forest ecosystems. To...

Patterns and trends in forest elemental cycling can become more apparent in the presence of atmospheric perturbations. High-elevation forests of the northeastern United States have received large amounts of atmospheric deposition of pollutants, which have altered natural elemental cycling and retention rates in a variety of ways. This study examined atmospheric deposition of nitrogen, sulfur and base cations, and their interactions in a high-elevation forest on Whiteface Mountain, New York. Eight years of elemental cycling data (1 986- 1993) have shown that at our main study site (1050-m...

The Forest Service goal for global change research is to establish a sound scientific basis for making regional, national, and international resource management and policy decisions in the context of global change issues. The objectives of the Northern Global Change Program (NGCP) are to understand: (1) what processes in forest ecosystems are sensitive to physical and chemical changes in the atmosphere, (2) how future physical and chemical climate changes will influence the structure, function, and productivity of forest and related ecosystems, and to what extent forest ecosystems will...

Several studies have shown that exposure to acid mist impairs cold tolerance of red spruce foliage, predisposing it to winter injury, which appears to be a major factor in the decline of montane populations of the species. Other studies have shown increases in calcium (Ca) concentration in canopy throughfall in montane spruce-fir forests, and decreases in foliar Ca concentration associated with exposure to acid mist. Studies of other plant species suggest that Ca may play a role in the development of cold tolerance or in stress response to cold. These considerations have led to the...

The influence of age of red spruce (Picea rubens Sarg.) cell suspensions on aluminum (Al) effects was studied by adding AICI3 (0.2, 0.5, and 1.0 mM) to the media on each day of a 7-day culture period and analyzing for changes in total cell mass, polyamines, arginine decarboxylase activity, and inorganic ions after 24 h of incubation. The effective concentrations of monomeric Al in the medium were found to be approximately 0.09, 0.23, and 0.48 mM, respectively. All levels of Al inhibited growth and increased cellular putrescine levels and arginine decarboxylase activity. Spermidine and...

Aluminum (Al) has been suggested to be an important stress factor in forest decline due to its mobilization in soil following atmospheric deposition of acidic pollutants. A major goal of our research is to develop physiological and biochemical markers of stress in trees using cell cultures and whole plants. Needles of red spruce (Picea rubens) collected from several sites in the northeastern United States and red spruce cells grown in suspension cultures were examined for polyamine and inorganic-ion content. The cells in culture were exposed to various concentrations of Al for different...