Treesearch

Within the past ten years a new class of genetic marker1 has risen to prominence as the tool of choice for many geneticists. Microsatellite DNAs, or simple sequence repeats (SSRs), were first characterized as highly informative genetic markers in humans (Weber and May, 1990; Litt and Luty, 1990), and have since been found in practically all organisms. SSRs are short stretches of repeated DNA sequence, where the repeats are composed of a particular 2 to 5 DNA nucleotide motif, and are organized in tandem arrays of 4 to >40 repeat units. Compared to other types of DNA sequence variation,...

Polymerase chain reaction (PCR) primer pairs for 21 simple sequence repeat (SSR) loci in Pinus strobus L, and 6 in Pinus radiata D. Don were evaluated to determine whether SSR marker amplification could be achieved in 1O other conifer species. Eighty percent of SSR primer pairs for (AC) loci that were polymorphic in P. strobus also amplified SSR loci in two other soft pines of the subgenus Strobus but not in seven hard pines of the subgenus Pinus nor in Picea glauca (Moencb) Voss or Pseudotsuga menziesii (Mirb.) Franco. The six P. strobus SSR primer pairs that did amplify loci from...

Canker expansion and the amount of callus tissue formed were measured monthly on 60 ramets from each of five trembling aspen (Populus tremuloides Michx.) clones that had been inoculated in wounds with Entoleuca mammata (= Hypoxylon marnmatum (Wahl.) Mill) over a 12-month period. At the clone level, the prevalence of nonlethal cankers within clones prior to the study had no correlation with canker expansion with three of the five clones. Greenhouse inoculation of ramets derived from the same five clones resulted in the same resistance rankings as main-stem inoculations in the field. One...

We investigated how environmental gradients measured along the St. Croix River in Minnesota and Wisconsin, U.S.A., influenced the turtle assemblage. Among seven species, the five most common species were generalists and had wide distributions throughout the study area. However, patterns in assemblage structure were related to environmental gradients along the river. Sex ratios were male-dominated for the five most common species, and few or no juveniles were captured during the study. The first two canonical axes of a canonical correspondence analysis accounted for 92.7% of the variation...

Many northern Michigan counties have grown in permanent residents and seasonal homes over the past several decades. Forest managers have observed that this influx of new forest owners affects public expectations and the range of socially acceptable forest management options. This shift in settlement and ownership patterns affects the landscape and has important ecological and economic implications. Information regarding landscape and ownership changes is necessary to make management and policy decisions. Changing patterns of land ownership and land parcelization were studied in three...

Today, there is keen interest in using alternative silvicultural systems like individual-tree selection, group openings and shelterwood because the general public feels these systems are more acceptable than clearcutting. Consequently, due to repeated entries into forest stands and the fact that residual crop trees have to be carried for a long period of time between re-entries, the damage to residual trees arising from harvest operations has to be better understood so that it can be minimized. The Missouri Ozark Forest Ecosystem Project (MOFEP), located in southeastern Missouri, is a...

Almost all forest management activities affect landscape pattern to some extent. Among the most obvious impacts are those associated with forest harvesting and road building. These activities profoundly affect the size, shape, and configuration of patches in the landscape matrix. Even-age management such as clearcutting has been applied in blocks of uniform size, shape, and distribution, as strip cuts with alternating leave and cut strips or as progressive cutting of strips, and as patches with variable sizes, shapes, and distributions. In contrast to the coarse-grain patterns produced on...

a-Pinene and ethanol were released in the approximate proportions 1:0.1, 1:0.9 and 1:9 (at 21oC). Ethanol, released in the range of 3-279 mg/day, generally synergized the attraction of T. piniperda to a-pinene(30 mg/day at 21oC), although attraction to the mixtures varied within and between years. The low release rate of ethanol together with a-pinene attracted a significantly higher number of beetles than a-pinene alone in 1995, April of 1996, and in 1997. Lures with the medium release rate of ethanol were the most attractive only in March of 1996. The high dose of ethanol significantly...

Site-preparation and regeneration methods for white spruce (Picea glaucu (Meench) Voss) were tested near Fairbanks Alaska, on two upland sites which had been burned in a wildfire and salvage logged. After 5 and 10 years, white spruce regeneration did not differ among the four scarification methods but tended to be lower without scarification. Survival of container-grown planted seedlings stabilized after 3 years at 93% with scarification and at 76% without scarification. Broadcast seeding was also successful, with one or more seedlings on 80% of the scarified 6-m2 subplots and on 60% of...

Nursery professionals should use only those poplar clones that have proved to be hardy and pest- and disease-resistant.