Aspen, Populus

Waterfowl feeding in areas subjected to extensive nickel pollution — such as smelters and nickel-cadmium battery plants — are at special risk because waterfowl food plants in those areas contain 500 to 690 mg Ni/kg DW (Eastin and O Shea 1981). Dietary items of the ruffed grouse (Bonasa umbellus) near Sudbury, Ontario, had 32 to 95 mg Ni/kg DW, whereas nickel concentrations in grouse body tissues usually contain less than 10% of the dietary level. Nickel concentrations in aspen (Populus tremula) from the crop of ruffed grouse near Sudbury ranged from 62 mg/kg DW in May to 136 mg/kg DW in September (Chau and Kulikovsky-Cordeiro 1995), which shows the role of season in dietary nickel composition. 

Columbia River Washington, 1985-87, near reactor, 90Sr Largetooth aspen, Populus grandidentata, 22eRa Near uranium tailing plant vs. control site Leaves 53 DW vs. 4 DW 4... 

The dominant species are the spruce (Picea excelsa), the birch (Betula verrucosa, B. pubescens), the aspen (Populus tremula), and the alder (Aims incana). The moss and low bush layer is represented by the blueberry-bush (Vaccinium myrtiilus), hypnic mosses, separate species of cowberry (Vaccinium uliginosum) and flowering plants. The biomass of these Spruce Forest ecosystems reaches 10 ton/ha at the age of 100-150 years (Table 4). 

Relatively pure xylan isolated from the holocellulose of aspen (Populus) wood is said to contain 85% of xylose residues.78 One of the characteristic properties of xylan is its ease of hydrolysis. Because it hydrolyzes much more readily than cellulose, mild acid treatment may be employed to bring about preferential hydrolysis of xylan from plant material. Xylose is ordinarily prepared in the laboratory by direct sulfuric acid hydrolysis of the native xylan in ground corn cobs.74 Hydrolysis in hydrochloric acid proceeds rapidly, but decomposition to furfural also occurs to some extent.76 A commercial method for the production of D-xylose from cottonseed hulls76 and straw77 and from corn cobs17 78 has been described. 

Quaking aspen Populus tremuloides Scales of flower buds Ruffed grouse Bonasa sp. Coniferyl benzoate Jakubas etal., 1989... 

Female flowers of dioecious trees are better defended than males. RuflFed grouse, Bonasa umbellus, prefer male flowers of quaking aspen, Populus tremuloides, in winter, and leaves of male specimens in summer (Svoboda and Gullion 1972). Ruffed grouse also feed more on male trees of balsam poplar (Bryant etal, 1991). 

The particular wood species we chose for this study is aspen (Populus tremuloides), which is plentiful in Canada and in the northern U.S.A. The chemical composition we found to be glucan 53.4%, xylan 14.9%, total carbohydrate 79.0%, lignin 17.1% and extractives 3.8%. We would expect total fermentable sugars of about 56% in this sample of aspen in anhydro form (Timell has reported about 60% in another sample (15)) which upon hydrolysis would yield about 1,250 lb wood sugars per ton of wood (dry basis), from the stoichiometry. Theoretical conversion of this sugar to ethanol would yield 640 lb or 81.1 gallons of anhydrous... 

Table I. Secondary Compounds Identified In Leaves and Bark of Quaking Aspen (Populus tremuloldes Mlchx)...

Hu, W.-J. et al.. Compartmentalized expression of two structurally and functionally distinct 4-coumarate CoA ligase genes in aspen Populus tremuloides). Proc. Natl Acad. Scl USA, 95, 5407, 1998. 

Trembling aspen, Populus tremuloides, Ra Near uranium tailings plant vs. control site ... 

Triazine herbicides are primarily effective in controlling herbaceous weeds. A notable exception is the use of granular hexazinone for controlling woody invaders such as oaks (Quercus spp.) or aspen (Populus tremuloides) in conifer stands on medium- and fine-textured soils in the South or in boreal forests. Hexazinone also is used in the Maritime Provinces of Canada for controlling woody and herbaceous growth in natural Christmas tree stands (Townsend, 1995a). The impact of herbaceous plant cover is somewhat different from that of woody plant competitors, so control strategies on various forest conifer sites may differ. 

Prasad, R. and J.C. Feng (1990). Spotgun-applied hexazinone Release of red pine (Pinus resinosa) from quaking aspen (Populus tremuloides) competition and residue persistence in soil. Weed Technol., 4 371-375. 

Table 6.2.2. Yields on nitrobenzene and cupric oxide oxidation products from Norway spruce (Picea abies) and aspen (Populus tremuloides) woods...

Aspen (Populus tremuloides) steam explosion ligmnbc - 25 bars, 4 5s 254 415 669 1 63... 

Rier, S. T., Tuchman, N. C., Wetzel, R. G. Teeri, J. A. (2002). Elevated-C02-induced changes in the chemistry of quaking aspen (Populus tremuloides Michaux) leaf litter subsequent mass loss and microbial response in a stream ecosystem. Journal of the North American Benthological Society, 21, 16-27. 

When beavers first colonize a site they begin by harvesting the most palatable species, such as aspen (Populus spp.) or willow (Salix spp.). Over time, they change the vegetation by their selection of trees for food and construction of dams and lodges. Eventually, often only the least preferred conifers are left, and the beavers move to a new area until some of the depleted vegetation has regenerated. Beavers move back in, and the cycle repeats. 

Study the beavers responses to juvenile vs. adult growth forms. Species used will depend on availability. Best are aspen (Populus tremuloides or P. grandidentata) or cottonwood (Populus deltoides). 

Fig. 8.1 Feeding preferences by free-ranging beavers Castor canadensis) for 3 species of northeastern deciduous trees and shrubs American beech (Fagus grandifolia), quaking aspen Populus tremuloides), striped maple (Acer pensylvanicum), witch hazel (Hamamelis virginiana), witch hobble (Viburnum lantanoides) and yellow birch (Betula alleghaniensis). The experiment was run over 10 days. Each morning the number of remaining sticks was counted. Only one of 10 beech sticks was taken after 10 days, while, at the other extreme, no sticks of aspen and striped maple remained after 4 and 5 days, respectively...

The size and shape of the blade are often characteristic of a species, and are useful in species identification. However, the leaf blades of some species, such as those of oaks Quercus), exhibit great variation in size and shape, sometimes even when on the same tree. Botanists use a large vocabulary of specialized terms to describe the leaf outline, margin, apex, base, and vestiture (surface covering). For example. Pine Pinus) leaves are considered acicular, meaning they are shaped like a needle Aspen (Populus) leaves are considered ovate, meaning they resemble a two-dimensional projection of an egg May apple Podophyllum) leaves are considered peltate, meaning they are shaped like a shield, and are attached to the stalk on the lower leaf surface. 

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