Ding, C., Schreiber, S. G., Roberts D.R., Hamann, A. and Brouard, J.S. (2017). Post-glacial biogeography of trembling aspen inferred from habitat models and genetic variance in quantitative traits. Scientific Reports 7, Article number: 4672
Hacke, U. G., Spicer, R., Schreiber, S. G. and Plavcová, L. (2017). An ecophysiological and developmental perspective on variation in vessel diameter. Plant, Cell & Environment 40: 831-845.
Summary: Variation in xylem vessel diameter is one of the most important parameters when evaluating plant water relations. This review provides a synthesis of the ecophysiological implications of variation in lumen diameter together with a summary of our current understanding of vessel development and its endogenous regulation.
Schreiber, S. G. and Thomas, B. R. (2017). Forest industry investment in tree improvement – a wise business decision or a bottomless pit? Answers from a new tree improvement valuation model for Alberta, Canada. The Forestry Chronicle, 93: 38-43.
Summary: Continued investment in tree improvement (TI) in Alberta is currently at a crossroads despite the demonstrated benefits of TI worldwide. According to private industry, the major roadblock for further investment is the minimal amount of genetic gain currently recognized in the annual allowable cut (AAC) set by the provincial government. In order to better understand the key parameters that drive profitability in TI programs, we developed the “Tree Improvement Investment for Forestry in Alberta” valuation model (TIIFA).
Thomas, B. R., Schreiber, S. G. and Kamelchuk, D. P. (2016). Impact of planting container type on growth and survival of three hybrid poplar clones at two nurseries in central Alberta, Canada. New Forests 47: 815-827.
Summary: We compared growth performance and survival of three hybrid poplar clones (Walker, Northwest and Okanese) planted as cuttings into five different Styroblock containers (412A, 415D, 512A, 515A, 615A) with increasing cavity volume and decreasing cavity density. The experiment was carried out under commercial growing conditions at two nurseries in central Alberta, Canada. After 175 days of growth, our results showed that initial cutting diameter appeared to be an important predictor of survival. Our study also identified Okanese as a well-rounded clone with great growth potential both above and below ground. From an operational standpoint, we found container types 512A and 515A the most cost-effective choices under the assumption that nursery space and budgets are limiting factors.
Summary: A response to Bittencourt et al.'s (2016) comment ‘On xylem hydraulic efficiencies, wood space-use and the safety-efficiency tradeoff’.
Summary: We tested the safety-efficiency hypothesis in branch xylem across 335 angiosperm and 89 gymnosperm species. Safety was considered at three levels: the xylem water potentials where 12, 50, and 88% of maximal conductivity are lost. Although correlations between safety and efficiency were weak (r2 < 0.086), no species had high efficiency and high safety, supporting the idea for a safety-efficiency tradeoff. However, many species had low efficiency and low safety. There appears to be no persuasive explanation for the considerable number of species with both low efficiency and low safety. These species represent a real challenge for understanding the evolution of xylem.
Summary: Hybrid poplars are an important renewable forest resource known for their high productivity. In this study, we assessed the variation of hydraulic traits and leaf size in five hybrid poplar clones planted at 10 test sites in central Alberta. Measurements were conducted on 2-3-year old branches from the lower to mid crown and vigorously growing current-year shoots from the upper crown. We found strong relationships between vessel diameter, cavitation resistance, xylem- and leaf-specific conductivity as well as leaf area. Leaf size emerged as an interesting and easily quantifiable trait, which could serve as an additional screening tool when selecting for drought tolerant genotypes in forest management and tree improvement programs.
Summary (see also here): Xylem vessel diameters represent an important adaptive trait in boreal forest trees. In this reciprocal transplant experiment along a boreal climate gradient, we found that vessel diameters strongly correlate with moisture availability and generally show a high degree of phenotypic plasticity. Much of the observed variability in vessel diameter is due to phenotypic plasticity and could not primarily be attributed to genetic differences among populations.
Summary: The distribution of many temperate species is restricted by a trade-off between their capacity to survive winter extremes in the north (or high elevation) and their ability to compete with better-adapted species in the south (or low elevation range limits). In this large-scale reciprocal transplant experiment with trembling aspen we found that long distance seed transfers in a northwest direction (1,600 km and more) were connected with superior growth and similar survival rates when compared to locally adapted populations. This study demonstrated that assisted migration prescriptions have considerable potential to enhance forest productivity.
Summary: This study evaluated the long-term effect of winter stress on growth performance and survival of 47 hybrid poplar clones. Water transport in trees requires a continuous water column to function. When water freezes, dissolved gas is forced out of solution forming little air bubbles, which are trapped in the ice. These embolisms can impair water transport during the start of the growing season and hence limit early growth. This study showed that the narrowest xylem vessel were associated with the least amount of embolisms and the tallest trees. Cold hardiness, timing of leaf senescence and bud break were not significantly related to growth. Our data suggest that reduction of freezing-induced embolism due to small vessel diameters is an essential adaptive trait to ensure long-term productivity of hybrid poplar plantations in boreal planting environments.
Summary: Growth performance in forest trees is often linked with efficient water conduction from the roots to the leaves through a network of water conducting pipes known as xylem vessels. A comparison of hydraulic traits within hybrid poplars and trembling aspen showed that tree height was strongly associated with smaller xylem vessel diameters. Between the two groups, aspen was better adapted to drought by having a more stress resistant xylem network and conservatively operating stomata to minimize water loss through the leaves. The data also suggest that vessel diameter may be a key trait in evaluating growth performance in a boreal environment.
Summary: In this study, we describe a DNA extraction method that combines the advantages of the traditional CTAB extraction with those of DNA extraction kits by leaving out hazardous reagents such as SDS and phenol. Furthermore, we describe adequate conservation solutions usable in the field and in the lab for the efficient fixation of moon snail tissue to be used for DNA extraction and PCR amplification.
Summary: We investigated the occurrence of members of the predatory caenogastropod family Naticidae in the littoral of the island of Giglio, Tuscany, Italy. We recorded a total of 8 species and provide images of living animals for 7 out of the 8 species encountered. Our survey included a systematic collection of egg masses ("sand collars"), which were hatched in the laboratory. The obtained larvae, as well as the sand collars themselves, were used for molecular analysis. We identified one additional naticid species for which no adult specimens or shells were found.