Mathew Smidt

Harvest caused soil disturbance decreased suckering capacity of quaking aspen (Populus tremuloides Michx.) following growing season harvests in Minnesota, USA

The effect of soil disturbance on quaking aspen (Populus tremuloides Michx.) sucker density and height growth was measured in mixed aspen and hardwood stands in east central Minnesota, USA. Loggers harvested stands during the growing season resulting in a range of soil disturbance conditions. Soil disturbance and parent stand aspen density accounted for a significant amount of the variation in suckering two full growing seasons after the harvest. Mineral soil exposure did not significantly affect total sucker density, but decreased sucker height growth as measured by the cumulative height of all suckers in a plot (sucker length) and density of suckers more than 1.2 m tall. Both shallow ( 15 cm) soil disturbance caused by machine traffic reduced sucker density and sucker length. Results indicated an effect of machine traffic on suckers in trafficked areas, but not adjacent areas. The long-term effects of reduced height growth in disturbed areas and severely reduced density in trafficked areas are not well understood. Loss in early height growth is likely to have long-term effects on productivity, and it is unlikely that aspen will recolonize rutted areas in time to recover full aspen productivity in trafficked areas in one rotation.

Determining the effects of felling method and season of year on the regeneration of short rotation coppice

There is increasing interest in plantations with the objective of producing biomass for energy and fuel. These types of plantations are called Short Rotation Woody Crops (SRWC). Popular SRWC species are Eucalypt (Eucalyptus spp.), Cottonwood (Populus deltoides) and Willow (Salix spp.). These species have in common strong growth rates, the ability to coppice, and rotations of 2–10 years. SRWC have generated interest for many forest products’ companies (seeking for diversification or energy self-sufficiency) and private landowners, and although they might help with the supply for the expected growth on the bioenergy and biofuels market, there are still several concerns about how and when to harvest SRWC to maximize their ability to coppice. SRWC have elevated establishment and maintenance costs if compared to other type of plantations, but due to the coppicing ability, the same plantation may be harvested up to 5 times without the need of establishing a new one. Study plots were installed at six locations in Florida, Mississippi and Arkansas, and were cut with a chainsaw and a shear head during summer and winter, to determine the effects of felling method and season on coppice regeneration. Thus, plots were divided into areas of four different treatments: shear-winter, saw-winter, shear-summer, saw-summer. Harvesting eucalypt and cottonwood trees during winter resulted in better survival rates than harvesting during summer; however, there was no effect of felling method on coppice regeneration. Finally, no statistically significant difference was found on coppice regeneration of black willow when harvested during winter or summer with a chainsaw or a shear head.

High tonnage harvesting and skidding for loblolly pine energy plantations

Abstract The southeastern United States has a promising source for renewable energy in the form of woody biomass. To meet the energy needs, energy plantations will likely be utilized. These plantations will contain a high density of small-stem pine trees. Since the stems are relatively small when compared with traditional product removal, the harvesting costs will increase. The purpose of this research was to evaluate specialized harvesting and skidding equipment that would harvest these small stems cost efficiently. The feller-buncher utilized was a Tigercat 845D with a specialized biomass shear head. The skidder was a Tigercat 630D equipped with an oversized grapple. This equipment was evaluated in a 4-hectare stand with characteristics of a southern pine energy plantation. During the study, the feller-buncher achieved an average production rate of 47 green tonnes/productive machine hour (gt/PMH) and the skidder had an average production rate of 112 gt/PMH. A before-tax cash-flow model was used to deter...

Characterizing exposure to physical risk factors among reforestation hand planters in the Southeastern United States

Low back and neck/shoulder pain are commonly reported among reforestation hand planters. While some studies have documented the intensive cardiovascular demands of hand planting, limited information is available regarding exposures to physical risk factors associated with the development of musculoskeletal disorders (MSDs) among hand planters. This study used surface electromyography (EMG) and inertial measurement units (IMUs) to characterize the muscle activation patterns, upper arm and trunk postures, movement velocities, and physical activity (PA) of fourteen Southeastern reforestation hand planters over one work shift. Results indicated that hand planters are exposed to physical risk factors such as extreme trunk postures (32.5% of time spent in ≥45° trunk flexion) and high effort muscle exertions (e.g., mean root-mean-square right upper trapezius amplitude of 54.1% reference voluntary exertion) that may place them at increased risk for developing MSDs. The findings indicate a need for continued field-based research among hand planters to identify and/or develop maximally effective interventions.

Coppicing evaluation in the Southern USA to determine harvesting methods for bioenergy production

ABSTRACT Woody biomass is an excellent source of renewable energy in terms of cost-benefit and availability. Short rotation woody crops (SRWC) meet intensive wood demand due to their fast growth and ability to coppice. There are uncertainties related to the feasibility of harvesting multiple-stem coppice trees with current technology. In this study, we investigated the physical attributes of two SRWC species, 2 years after harvest. A logistic regression was fit in an attempt to determine whether the number of surviving stems per stump (2 or fewer; 3 or more) had a relationship with the damage caused during harvest and the diameter classes of the stumps. The species used in this experiment were Eucalyptus urograndis in Florida, and Populus deltoides in Arkansas. Stem crowding and clump dimension was also collected from the coppice trees 2 years after harvest. In addition, the re-sprouting patterns from different seasons of the year (summer and winter) were compared. Results from both species showed that stump diameter is positively related with stem crowding. A minimal percentage of the clump dimensions exceeded the established threshold that would put these multi-stem trees in a challenging spot for subsequent harvesting operations with small-scale machinery.

Full Shift Physical Activity among Reforestation Hand Planters: A Feasibility Study

Reforestation in the Southeastern United States is predominantly accomplished through the use of hand planting methods. A high prevalence of musculoskeletal pain has been reported among reforestation hand planters. This feasibility study aimed to characterize the intensity of physical activity using inertial measurement units (IMUs) placed on the upper arms, trunk, and waist of ten reforestation hand planters during full shift work. Results indicated that participants spent the majority (>50%) of their time performing moderate, vigorous, or very vigorous levels of physical activity. Exposure estimates among planters exceed many other occupations that commonly report a high prevalence of musculoskeletal health outcomes, including healthcare and construction workers. Additional research into the working demands of reforestation hand planters is warranted.