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Leaf morphological variation among paper birch (Betula papyrifera Marsh.) genotypes across Canada  [PDF]
Anjala Pyakurel, Jian R. Wang
Open Journal of Ecology (OJE) , 2013, DOI: 10.4236/oje.2013.34033

Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, we analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, we examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin. We found significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, we expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, we analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. Our results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface. Thus, all these leaf morphological features provide a basis for the birch to reduce water loss from leaves and balance water use efficiency in reduced precipitation. Furthermore, the leaf characteristics measured may also

Leaf Morphological and Stomatal Variations in Paper Birch Populations along Environmental Gradients in Canada  [PDF]
Anjala Pyakurel, Jian R. Wang
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.511166

Variations in leaf morphology and stomatal characteristics have been extensively studied at both inter- and intraspecific levels although not explicitly in the context of paper birch (Betula papyrifera Marsh) populations. The birch populations might have developed the leaf variations that allowed them to adapt to a wide climatic gradient. Therefore, in this study we examined variations in the leaf morphological and stomatal characteristics of sixteen paper birch populations collected across Canada and grown in a common garden. We also examined the relationship between these leaf characteristics and the climate of the population’s origin. Significant genotypic differences were found in the leaf characteristics measured among the birch populations. Thus, we expected that the observed leaf variations may be partly explained as natural diversity in the birch due to differences in environment of origin. We noticed that along mean annual precipitation and aridity gradients, hair density on leaf adaxial surface had decreased whereas stomatal density increased significantly. Our results showed that the populations with larger leaf area and specific leaf area had higher hair density but low stomatal density. These leaf characteristics provided a structural basis in reducing water loss through leaves and increasing water use efficiency. A trade-off between stomatal area and density resulted in this study might be a strategy of the birch to balance stomatal conductance in decreased precipitation.

Assessing effects of seed source and transfer potential of white birch populations using transfer functions  [PDF]
Oluwatobi A. Oke, Jian R. Wang
Open Journal of Ecology (OJE) , 2013, DOI: 10.4236/oje.2013.35041

Trees have adapted to their local climates, but with changes in the climate, they may currently or in the near future occupy climates that are sub-optimal for growth and survival. The goal of current reforestation is therefore to establish a new generation of trees with growth adapted to the future climate(s). Here, we present preliminary data of a study assessing the effects of seed source and transfer potential of white birch populations. Seeds from twenty-five white birch (Betula papyrifera Marsh.) populations collected acrossCanadawere grown in the greenhouse and observed for emergence time, germination and growth. The seedlings were later planted in a common garden. After one year, the seedlings were measured for height, root-collar diameter (RCD) and survival rate and average volume per seedling calculated. Transfer functions were used to estimate the climatic distance from which populations may be transferred to the test site. There was a significant effect of population on all growth variables. Initial height was positively correlated with 1-year height and survival. Germination rate negatively correlated with emergence time. Principal component analysis showed effects of seed origin on performances of the populations in the common garden. Summer temperature was the best predictor of the transfer distance.

The impact of birch seedlings on evapotranspiration from a mined peatland: an experimental study in southern Quebec, Canada
E. Fay,C. Lavoie
Mires and Peat , 2009,
Abstract: Dense stands of birch (Betula spp.) on abandoned peat workings have often been identified as potential barriers to site restoration, but little research has been conducted to evaluate their impact on water resources. The objective of this experimental study was to determine whether birch seedlings established on an abandoned mined peatland in eastern Canada had a significant impact on evapotranspiration. Transpiration rates from birch seedlings planted in containers filled with Sphagnum compost were measured gravimetrically. Unplanted containers were used to similarly measure evaporation rates from bare peat. On average, the measured rates of evaporation (per unit area) from peat were 2.5 times the rates of transpiration from birch leaves. However, if the total leaf area of a dense birch population established on an abandoned mined peatland is considered, the total amount of water lost through birch transpiration could be higher than that lost by evaporation from the peat surface. This study provides a rough estimate of potential water losses due to birch seedling transpiration, and indicates that a dense population of birch on a mined peatland may influence site hydrology even at the early establishment phase (seedlings). Consequently, recently abandoned mined peatlands should be restored rapidly to prevent the establishment of birch trees.
Aneuploids in the shrub birch Betula humilis populations in Poland
Katarzyna A. Jadwiszczak,Ewa Jab?ońska,Stanis?aw K?osowski,Agata Banaszek
Acta Societatis Botanicorum Poloniae , 2011, DOI: 10.5586/asbp.2011.015
Abstract: Shrub birch (Betula humilis Schrk.) is endangered glacial relict growing in natural and drained fens and transitional mires. At present study we examined karyotypes of 103 individuals of B. humilis, collected in six populations from eastern and northeastern Poland. We found 60% of diploid individuals with 2n = 28. The rest of studied plants were aneuploids with 26, 27, 29, 30 and 31 chromosomes in their karyotypes. High frequencies of aneuploids in Polish populations of B. humilis could be a consequence of: (i) hybridization with congeneric species, (ii) stress resulting from range fragmentation, (iii) karyotype instability of individuals with 2n ≠ 28, or (iv) vegetative reproduction.
Radial Growth Responses of Four Deciduous Species to Climate Variables in Central Ontario, Canada  [PDF]
Martin Kwiaton, Jian R. Wang
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.614226
Abstract: To address the central question of how climate change influences tree growth within the context of climate will become warmer and drier in central Ontario, we used dendroclimatological analysis to understand the radial growth responses of four co-occurring hardwood species: sugar maple (Acer saccharum Marsh.), yellow birch (Betula alleghaniensis Britton), American beech (Fagus grandifolia Ehrh.), and red oak (Quercus rubra L.) to climatic variables in central Ontario, Canada. Ring width chronologies were developed for the target species within three regions (Algonquin Park, Haliburton, and North Bay) of the study area. Seven of the eleven chronologies exceeded the 0.85 expressed population signal (EPS) and were used for further analysis. Mean sensitivity and standard deviation values of the Ontario chronologies indicated lower sensitivity to climate fluctuations than in southern North America. Positive correlations with precipitation variables from the current and prior growing season supported previous studies in sugar maple, while a positive response to growing degree days suggested the importance of warmer temperatures and a longer growing season at the northern limit of the distribution range of sugar maple. Yellow birch ring width was correlated with precipitation from the previous growing season and from the end of the current growing season also suggesting that mature trees with deep root systems might utilize moisture from deep soil. Radial growth of American beech positively correlated to precipitation of the previous season, suggesting that the amount of moisture reserves stored in the previous year might affect growth in the following year. Drought stress at the start of the growing season for red oak had negative correlations with precipitation in August indicating possible cessation of cambial activity. This decline in growth process would also affect ring width of red oak the following year as expressed by negative correlations with mean annual temperature from the previous year. Abnormally, warm seasonal temperatures may be indicative of drought stress in red oak.
Impacts of Elevated Atmospheric CO2 and O3 on Paper Birch (Betula papyrifera): Reproductive Fitness  [cached]
Joseph N. T. Darbah,Mark E. Kubiske,Neil Nelson,Elina Oksanen
The Scientific World Journal , 2007, DOI: 10.1100/tsw.2007.42
Transcriptomic Analysis of Phenotypic Changes in Birch (Betula platyphylla) Autotetraploids  [PDF]
Huai-Zhi Mu,Zi-Jia Liu,Lin Lin,Hui-Yu Li,Jing Jiang,Gui-Feng Liu
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms131013012
Abstract: Plant breeders have focused much attention on polyploid trees because of their importance to forestry. To evaluate the impact of intraspecies genome duplication on the transcriptome, a series of Betula platyphylla autotetraploids and diploids were generated from four full-sib families. The phenotypes and transcriptomes of these autotetraploid individuals were compared with those of diploid trees. Autotetraploids were generally superior in breast-height diameter, volume, leaf, fruit and stoma and were generally inferior in height compared to diploids. Transcriptome data revealed numerous changes in gene expression attributable to autotetraploidization, which resulted in the upregulation of 7052 unigenes and the downregulation of 3658 unigenes. Pathway analysis revealed that the biosynthesis and signal transduction of indoleacetate (IAA) and ethylene were altered after genome duplication, which may have contributed to phenotypic changes. These results shed light on variations in birch autotetraploidization and help identify important genes for the genetic engineering of birch trees.
Measurement of respiration amount of white birch(Betula platyphylla) population in the mountainousregion of Beijing
Fang Jingyun,Wang Xiaoke,
Fang Jingyun
,Wang Xiaoke

环境科学学报(英文版) , 1995,
Abstract: Measurement of forest community respiration is very important for clarifying the processes of mat-ter cycle in forest ecosystem. Measurement of respiration of white birch (Betula platyphylla) population inthe mountainous region of Beijing was reported herein and its results showed that the diameter frequency dis-tribution of the woody orgaris was fitted by a power equation and the respiration rates of the organs decreasedwith their increasing diameter. These formulae to calculate the total respiration amount of every organ for anindividual were introduced and those corresponding parameters were given. The quantitative relationship toestimate population respiration amount from three size was proposed. Using the ahave relationships, the an-nual respiration amount of white birch population was estimated to be 10. 8t CO_2/ha/a , of which stem , root ,branch and leaf were 1. 4 , 2. 0 , 2. 8 and 4. 7 tCO_2/ha/a, respectively.
Interactive Effects of Elevated [CO2] and Soil Water Stress on Leaf Morphological and Anatomical Characteristic of Paper Birch Populations  [PDF]
Anjala Pyakurel, Jian R. Wang
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.55084

The leaf morphological and stomatal characteristics of four paper birch (Betula papyrifera Marsh) populations, grown at four treatment conditions of carbon dioxide [CO2] and soil water levels were investigated to determine whether future increases in atmospheric [CO2] and water deficit affected the leaf characteristics. The populations from Cussion Lake, Little Oliver, Skimikin and Wayerton were grown for 12 weeks under ambient (360 ppm) and elevated (720 ppm) [CO2] at both high and low water levels. The populations significantly differed in leaf area and stomatal characteristics due to the interaction effects of [CO2], water levels and population differences. Most leaf morphological characteristics and stomatal density varied due to the effects of [CO2] and/or populations, but not due to the effect of water levels. Although elevated [CO2] alone barely affected stomatal area of the birch populations, simultaneous elevated [CO

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