Treesearch

A 38-year period of group selection in northern hardwoods is resulting in a permanent composition of one-quarter to one-third intermediate and intolerant species. The diameter distribution follows the inverse J-shaped form that typifies uneven-aged stands. Uneven-aged management based on a combination of group and single-tree selection appears to be silviculturally sound.

A new genus, Canalicephalus, of the subfamily Blacinae is described along with 4 new species, C. orientalis from Borneo, C. novus from New Guinea, and C. bakeri and C. mindanao, both from the Philippines. Keys are included to separate these 2 genera and the 4 species.

The white-footed mouse, Peromyscus leucopus Rafinesque, and the short-tailed shrew, Blarina brevicauda Say, 2 small mammal predators of the gypsy moth, have demonstrated the ability to pass significant amounts of infectious nuclear polyhedrosis virus (NPV) through their alimentary tracts. Ninety-five percent of the gypsy moth larvae fed fecal preparations from NPV-challenged mammals died during infectivity tests, whereas only 6% of larvae fed control fecal preparations died. The ability of these mammals to pass large amounts of infectious NPV may be important in the distribution of NPV in...

Gypsy moth Lymantria dispar L. larvae were exposed to Apanteles melanoscelus (Ratzeburg) females contaminated with nuclear polyhedrosis virus. Three methods of contamination (ovipositor, total body surface, and exposure to infected hosts) and two exposure periods (2 and 24 hours) were tested. A significantly greater incidence of larval mortality caused by virus occurred among larvae exposed to contaminated than among larvae exposed to uncontaminated parasites for 2 and 24 hours. No significant differences occurred in larval mortality caused by virus for the 3 methods of contamination for...

This paper describes inter- and intraspecific protein variation in the 3 closely related species of the Simulium jenningsi black fly group, S. jenningsi Malloch, S. Nyssa Stone and Snoddy, and S. n. sp. P. Snoddy and Bauer. Variation is described at single loci coding for the enzymes, phosphoglucomutase, phosphoglucoisomerase, malate dehydrogenase, and lactate dehydrogenase. Data are analyzed to assign genetic relationships among the 3 species and to suggest their status as sibling species. The application of electrophoretic methodology has revealed S. n. sp. P. to be the principle biter...

Concentrations of N, P, K, Ca, Mg, and Na were measured in rain and snow in the open, and in throughfall and stemflow under black spruce and aspen forests in north-central Minnesota. Concentrations of total P in rain and black spruce throughfall were inversely related to storm size. Annual precipitation nutrient inputs to the forest floor were calculated for each site. In general, nutrient contributions from snow were less than 10% of the annual nutrient input from precipitation at each site, and differences in snow nutrient input between sites were minimal. Rainfall nutrient input...

Nutrients transported in surface runoff and interflow from an undisturbed aspen-birch (Populus tremuloides Michx., and Betula papyrifera Marsh.) forest (6.48 ha) in northern Minnesota were measured for 3 years. Surface runoff from snowmelt accounted for 97% of the average annual surface runoff and for 57% of the average annual water loss. Slope aspect influenced the amount, rate, and time of snowmelt runoff. In surface runoff, organic nitrogen (N) comprised 80% of the total N load, and organic (+ hydrolyzable) phosphorus (PI comprised 45% of the total P load. The quantities of cations in...

Six nature programs for urban children were studied from 1970 to 1974. Social networks in the camping programs and children's choices of locations for various leisure activities were examined. Return rates were found to correlate significantly with the intricacy of the social networks.

Although natural processes operate in urban areas, they are difficult to observe. Much discussion during the symposium-fair was devoted to finding ways to improve urban children's environmental understanding through environmental education programs. But before effective environmental education programs can be developed, research is needed to: test the effectiveness of various approaches to teaching environmental education in relation to differences among children; help define testable program goals that relate to a child's level of comprehension; develop better methods of training teachers...

The concepts and techniques of transactional analysis (TA) can usefully be applied to outdoor challenge programs aimed at facilitating personal growth, developing responsibility, and teaching cooperative behavior. Passive behavior results from discounting of the self and others; four levels of it have been identified, and TA offers various means of preventing or confronting it. A no-discount contract and individual growth or learning contracts are prerequisite to responsible behavior. Both structural analysis (identifying ego states) and script analysis are valuable tools for detecting and...