Treesearch

The forests of the 20-state Northern Region are maturing. The portion of timberland covered by sawtimber-size stands has increased and the area in the sapling/seedling-size stands has decreased. Growing-stock volume has doubled since the early 1950's. Most of the recent gains in volume have occurred on sawtimber-size trees, resulting in large increases in sawtimber volume. Individual species are growing and being removed at different rates, causing changes in the species composition of the forest. For example, red maple (Acer rubrum L.) is increasing at a faster rate than many of the more...

A micropropagation system has been established for the regeneration of superior trees of Ulmus americana L., the American elm. The development of a reliable regeneration system is also required as a prelude to genetic transformation of selected genotypes. The effects of explant source, media formulations, and plant growth regulator concentrations on shoot regeneration of juvenile and mature American elm selections were examined. Hypocotyls, leaves, and stems taken from seedlings and stem segments taken from root cuttings of a mature tree, selection #8630, were used. Media formulations...

The process by which oak pistillate flowers become acorns is reasonably understood from an anatomical perspective; however, the way that various factors influence this process is still unclear. This study examined acorn production in a small population of white oak and black oak trees in central Missouri, from 1990 to 1995, in relation to weather variables (maximum and average temperature, relative humidity, fog, rain, and hail) at the time of pollination. There was large tree-tree and year-year variation in the size of flower crops and the dates when the flowers aborted. In the white...

Artificial regeneration of northern red oak (Quercus rubra L.) has had variable success over time. Current nursery practices generally involve the growth of seedlings to a standardized height and form with little regard to seed source, seedling quality, or subsequent field performance. Additionally, there is not an accepted culling criteria for hardwood nursery stock. Northern red oak seedlings need sufficient height and root growth in the nursery in order to receive adequate sunlight, water, and nutrients when planted in the field. In the Fall of 1993, acorns were collected from 73...

Crown class and diameter of 704 white ash (Fraxinus americana L.) > 0.5 inches dbh have been monitored at 10-yr intervals since 1927. Nominal stand age was 25 years in 1927. Although the density of white ash in the upper canopy declined from 14/acre to 3/acre between stand ages 25 through 85, the proportion of the upper canopy comprised by white ash only fell from 5.2% to 3.6%, respectively. In contrast, both absolute and relative density of lower canopy fell precipitously between stand ages 25 to 85, from 53/acre (4.5%) to 3/acre (0.5%). White ash ingrowth has never exceeded 2.6 trees/acre...

Bole diameter responses to fertilization, crown release, and fertilization x release treatments with untreated controls and treatment-by-year interactions were studied in pole-sized (approx. 43 years old) white oak (Quercus alba L.) crop trees. In the main study, fertilizer was applied by broadcast to plots at a rate of 150 lbs N and 35 lbs P2O5 per acre, and crown release removed competing trees around crop trees--dominate or codominate trees selected for favorable timber characteristic--in randomly selected plots during spring 1993. Another fertilizer application was applied during...

The role of fire in shaping the composition and structure of Quercus (oak)-dominated communities in the deciduous forests of eastern North America is becoming clearer but fire regimes are less well known. I analyzed the fire-scar patterns in 14 oak cross sections from a mixed-oak stand in Vinton County, southeastern Ohio, to determine the frequency and seasonality of fire. This oak stand was even-aged and originated in the mid-1850s, so the fire history is representative of the period after Euro-American settlement. The tree rings were crossdated, calendar year of the fire sears was...

While the effects of disturbance such as insect defoliation have been well documented in terms of overstory mortality and woody species regeneration, little is known about such disturbance effects on herbaceous flora, or non-commercial woody species. Since ground vegetation is often more sensitive to site and environmental conditions, such information may be valuable in understanding successional development in these forests and can be used as an indication of forest resilience and forest change. Furthermore, there exists some controversy about the effect of thinning on understory vegetatio...

The volume and decay stages of down dead wood were evaluated across a chronosequence of 46 silvicultural openings and 10 uncut control stands to determine how down dead wood volume changes with stand development. Openings ranged in age from 8 to 26 years and were divided into three age groups: (1) < 12 years, (2) 12-16 years, and (3) > 16 years. Individual logs were assigned to 5 decay stages ranging from freshly fallen (stage 1) to near total decomposition (stage 5). The volumes of down dead wood in age groups 1 and 2 were greater than that of the control plots (80-100 years old) and...

Following the Midwest flood of 1993, a study was initiated along a 39-mile segment of the Missouri River to determine if there was an association between woody corridors and levee stability. A systematic sample of levee failures revealed that primary levees which did not fail had a significantly wider woody corridor than failed levees. Analysis of the total inventory of failed levees revealed that as the width of the woody corridor decreased, the length of the levee failure increased. Number of levee failures and their severity of damage could be reduced if woody corridors were at least...