Raymond O. Miller

Genotype × environment interaction analysis of North American shrub willow yield trials confirms superior performance of triploid hybrids

Development of dedicated bioenergy crop production systems will require accurate yield estimates, which will be important for determining many of the associated environmental and economic impacts of their production. Shrub willow (Salix spp) is being promoted in areas of the USA and Canada due to its adaption to cool climates and wide genetic diversity available for breeding improvement. Willow breeding in North America is in an early stage, and selection of elite genotypes for commercialization will require testing across broad geographic regions to gain an understanding of how shrub willow interacts with the environment. We analyzed a dataset of first‐rotation shrub willow yields of 16 genotypes across 10 trial environments in the USA and Canada for genotype‐by‐environment interactions using the additive main effects and multiplicative interactions (AMMI) model. Mean genotype yields ranged from 5.22 to 8.58 oven‐dry Mg ha−1 yr−1. Analysis of the main effect of genotype showed that one round of breeding improved yields by as much as 20% over check cultivars and that triploid hybrids, most notably Salix viminalis × S. miyabeana, exhibited superior yields. We also found important variability in genotypic response to environments, which suggests specific adaptability could be exploited among 16 genotypes for yield gains. Strong positive correlations were found between environment main effects and AMMI parameters and growing environment temperatures. These findings demonstrate yield improvements are possible in one generation and will be important for developing cultivar recommendations and for future breeding efforts.

Establishment and development of northern white-cedar following strip clearcutting

Abstract Overbrowsing by white-tailed deer ( Odocoileus virginianus ) has created difficulties in regenerating northern white-cedar ( Thuja occidentalis L.) in Michigan during the last 30 years. This has prompted concerns among resource managers regarding the long-term sustainability of cedar forests. After reviewing many areas, we identified three that were strip clearcut 20–30 years ago and had successfully regenerated. We determined patterns of species establishment and height growth and computed the time interval over which this cedar was vulnerable to browsing by deer. Cedar comprised 51–82% of all trees and 36–70% of overstory trees in the three study areas. Balsam fir ( Abies balsamea (L.) Mill.), black spruce ( Picea mariana (Mill.) B.S.P.), and white spruce ( P. glauca (Moench) Voss) were important associates. Seedling establishment in these stands had continued for up to 20 years after clearcutting. However, all overstory trees were derived from advance regeneration or from seedlings that established within the first 10 years after cutting. Seedlings that established early but were overtopped by faster growing trees, or seedlings that established later than 10 years after cutting, were restricted to understory positions. It took 23–26 years after logging for two of our study sites to become fully stocked with cedar that were tall enough to escape overbrowsing by deer. The third area had no trees of this size, even after 20 years. Cedars successful regeneration on these strip clearcuts can be attributed to its aggressive colonization, the lack of faster-growing competitors, and limited herbivory over several decades. Extending this experience to other areas, where strip clearcutting has failed, will require an unprecedented, steadfast management policy.

Poplar and shrub willow energy crops in the United States: field trial results from the multiyear regional feedstock partnership and yield potential maps based on the PRISM-ELM model

To increase the understanding of poplar and willow perennial woody crops and facilitate their deployment for the production of biofuels, bioproducts, and bioenergy, there is a need for broadscale yield maps. For national analysis of woody and herbaceous crops production potential, biomass feedstock yield maps should be developed using a common framework. This study developed willow and poplar potential yield maps by combining data from a network of willow and poplar field trials and the modeling power of PRISM‐ELM. Yields of the top three willow cultivars across 17 sites ranged from 3.60 to 14.6 Mg ha−1 yr−1 dry weight, while the yields from 17 poplar trials ranged from 7.5 to 15.2 Mg ha−1 yr−1. Relationships between the environmental suitability estimates from the PRISM‐ELM model and results from field trials had an R2 of 0.60 for poplar and 0.81 for willow. The resulting potential yield maps reflected the range of poplar and willow yields that have been reported in the literature. Poplar covered a larger geographic range than willow, which likely reflects the poplar breeding efforts that have occurred for many more decades using genotypes from a broader range of environments than willow. While the field trial data sets used to develop these models represent the most complete information at the time, there is a need to expand and improve the model by monitoring trials over multiple cutting cycles and across a broader range of environmental gradients. Despite some limitations, the results of these models represent a dramatic improvement in projections of potential yield of poplar and willow crops across the United States.

Geographic variation in the essential oil monoterpenes of Liriodendron tulipifera L

The monoterpene component of Liriodendron tulipifera L. (Magnoliaceae) essential oils was quantitatively analysed in branch samples collected from an Ohio provenance test of 11 geographic seed sources representing the natural range of the species. Mean monoterpene composition of the essential oil is described and significant differences in the monoterpene composition among geographic sources are discussed.

A traditional ground-based system for woody biomass harvesting in Short Rotation Woody Crop (SRWC) plantations – a case study in Michigan

ABSTRACT Reconfigured forage harvesting equipment utilized for plantation biomass harvesting and processing is highly productive but is expensive and not yet widely used in short rotation woody crop (SRWC) production systems. Traditional timber harvesting equipment, on the other hand, has been widely used for decades and can be adapted for use in SRWC plantations. Productivity of these traditional systems is not well understood when utilized in such plantations. To that end, productivity and costs were evaluated for a traditional ground-based system (feller-buncher, skidder, loader, and grinder) in a 3.1-ha small-diameter hybrid poplar plantation in Escanaba, Michigan, USA. Operation cycle time predictive models were developed from a time and motion analysis. Operation productivity and costs were generated and then compared with published data for a reconfigured forage harvesting system. Compared values between the two systems included: machine hourly rate, in dollars per scheduled machine hour (

Initial greenhouse gas emissions and nitrogen leaching losses associated with converting pastureland to short-rotation woody bioenergy crops in northern Michigan, USA

/SMH), the production cost, in dollars per oven dry ton (

Origin and early development of northern white-cedar stands in northern Michigan

/ODT), and the system production rate, in oven dry tons per productive machine hour (ODT/PMH). The machine hourly rate and production cost of the traditional system were found to be

Yields of willow biomass crops across a range of sites in North America

284.00/SMH, and

Paper Birch and European White Birch Vary in Growth and Resistance to Bronze Birch Borer

22.30/ODT, respectively; while the production rate was found to be variably between 8.82–35.44 ODT/PMH. A sensitivity analysis was conducted on the traditional harvesting system to test the effect of machine utilization on production costs, where an equal utilization rate of 80% dropped production costs to

Specific Gravity of Hybrid Poplars in the North-Central Region, USA: Within-Tree Variability and Site × Genotype Effects

17.92/ODT. A net energy analysis was also conducted, demonstrating a net energy ratio of 24.8:1 for the traditional system.