The Trembling Aspen is also referred to as the Quaking Aspen (Populus tremuloides Michx)
A ramet is an individual plant belonging to a clone. The botanical term for a sucker is ramet. The clone originates from one ortet. An ortet is the original or mother plant. A clonal colony is also referred to as a genet. A genet is the group of genetically identical individuals, such as plants, fungi, or bacteria, that have grown in a given location, all originating vegetatively, not sexually, from a single ancestor. In plants, an individual in such a population is referred to as a ramet. All plants (ramets) reproduced asexually from a common ancestor (ortet) and have identical genotypes which means it is an exact clone or perfect copy of the original ortet. A genotype is the genetic constitution of an individual organism.
Tomáš Herben of the Department of Botany, Faculty of Science, Charles University and at the Institute of Botany, Czech Academy of Science relates rhizomes to clonal growth. Rhizome is from both Latin and Greek root rhizoma meaning “mass of tree roots”, and from the root rhizoun meaning “cause to strike root, root into the ground” and from the Green rhiz meaning “root” and -ome. In botany, rhizome is a horizontal, underground plant stem which is able to produce the shoot and root systems of a new plant. Duana A. Pelzer, also states that “Aspen (Populus tremuloides) dominates the southern treeline in western Canada, has long‐lived below ground connections between mother and daughter ramets, and reproduces vegetatively via resprouting rhizomes.” The Trembling Aspen clone can be called rhizomatous.
Scientists, foresters or gardeners can practice vegetative propagation using rooted cuttings, grafting, or tissue culture. In the case of the Trembling Aspen, the original plant is also called the ortet.
The Trembling Aspen root suckers are produced from meristems featured in the cork cambium of the root systems. The Cambium is a layer of tissue between the wood and the bark from the Latin cambium meaning “exchange” and Latin cambiare “change. The cork cambrium, also called a phellogen, produces an outer protective barrier or corky tissue, and an inner phelloderm- a thin, food conducting vascular tissue.
The roots twist, coil and undulate underground. Growing sideways, laterally, they do not reach lower than 40 cm (16 inches) below the surface of the soil and most often stay within 2 to 10 cm (1 to 4 in) from the soil surface.
A meristem is a collection of cells forming plant tissue in the zones where plant growth can take place. These undifferentiated cells (meristematic cells) have the capability for cell division, promoting growth and change. Meristem comes from the Greek root “merizein” which means “to divide” which is the main function of the merismatic cells, to change and divide thus providing new growth for the tree. Differentiated plant cells cannot produce new growth, as they cannot change.
The shoots develop following apical dominance. Apical dominance occurs when the shoot apex inhibits the growth of lateral buds so that the plant may grow vertically upwards towards the light. These shoots however, lie in wait, remaining dormant due to hormones called “Auxin” expressed by the main Trembling Aspen clone. High soil temperature, depletion of carbohydrate food sources, or excess soil moisture may inhibit the formation of suckers. If the Aspen Grove is disturbed, the hormonal balance is upset within the Trembling Aspen grove. There is a decrease in Auxin allowing meristem to develop into buds, then into shoots above ground, finally developing fully producing ramets which can be visibly seen above ground as part of the Trembling Aspen grove. Suckers originate after disturbances such as clearcutting, girdling, tree defoliation or fire.
When the suckers start to form, the parent root changes. The suckering rhizomatous root system has four parts:
- The root collar, stump or root cap
- The distal parent root
- The proximal parent root
- The adventitious roots
The root collar is the underground area of the Trembling Aspen sucker where it adjoins the stem. This root collar is the protective layer, so that apical meristem (upward changing new growth) is not affected by rocks, dirt or pathogens (germs.) The sucker roots and the parent roots cannot be distinguished from each other at the root collar, root cap or stump.
The distal parent root grows quite large to accommodate the new sucker formation. The distal parent root fills with juicy sap, and is quite succulent and tender. Distal means situated on the outside edge away from the point of attachment to the parent.
The proximal root which is on the close side of the root collar, or stump formation. Proximal means to be on the nearest to the point of attachment.
The adventitious roots of the newly initiated root suckers reveal growth downwards on the distal end of the roots reaching down to the root cambium of the Trembling Aspen clone or grove. Adventitious means formed accidentally or in an unusual anatomical position. These sucker roots will rely on the parent root for water and nutrients for the first few years. In some cases the suckers rely on the parent roots for more than 20 years. This interplay between parent root and ramet gives the sucker a distinct advantage over Aspen seedlings and other species arising on the forest floor.
Whereas shoots arising inside the meristem are one way to give rise to shoots as above, there are also shoots which arise from the exterior surface of Aspen roots from pre-existing primordia. It is believed that these primordia arise from injury or disturbance to the root system, perhaps by a grazing animal. Primordia comes from the Latin root prīmōrdiālis which is the earliest stage of development of the organism.
Root sprouting is the most commonly seen means of reproduction for the Trembling Aspen. This is referred to as vegetative asexual reproduction.
A Trembling Aspen grove or stand of trees is connected underground by this common root system originating from the ortet. Each Aspen Clone is dioecious. One Aspen stand of trees may be composed of a mosaic of clones with their roots interspersed with each other. Dioecious means that there are distinct male and female organisms, or boy and girl clones. A stamen is the pollen producing male organ of the flower. Pistils arise on the flowers of the female Trembling Aspen stands, and feature a base ovary, a style or pillar which extends from the ovary to the stigma. The stigma is sticky enabling it to capture the pollen from the male Trembling Aspen clone.
A Trembling Aspen feature aments, also referred to as catkins. Each catkin bears many tiny dense flowers. The name catkin comes from the German root “kätzchen,” or in Dutch “katteken” meaning kitten. The aments look like the furry tail of a kitten. The catkins can be anywhere from 1 to 8 cm in length (1-1/2” – 3”) The flowers with red stigmas are female flowers. The flowers bearing black, dark anthers are male flowers. The seeds will spread in the wind across distances of 500 meters (1,600 feet) up to several kilometers in heavy winds. The seeds are plumose, which means having many fine filaments or branches which give a feathery appearance. Seedlings have barriers to establishment because early spring rainfall in the semi-arid prairie regions may be followed by a dry period ~ killing newly germinated seedlings.
Trembling Aspen will hybridize, or cross with other species of poplar trees (Populus)
The extent of a single Trembling Aspen clone of trees can be determined by several features; morphology, and phenology. These two methods bring in the observation of the leaf size and shape, the character and colour of the bark, and the changes in the season. Morphological analysis is the study of the form and structure of organisms and their specific structural features such as the outward appearance of the shape, structure, colour, pattern and size of the visible aspects. Morphology has as its roots the Greek word, morphé “form” and logos “the study of.” The study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation) is the science referred to as phenology. Phenology means the study of the influence of climate on recurring natural phenomena, and is derived from phainō, which is Greek for “to show, to bring to light, make to appear” and logos.
Taking the observations one step further would be to employ a procedure called digital morphometrics. This digital approach utilizing scanned leaf images carefully tracking the location and statistics of each leaf, and comparing the digital scans of each leaf recording the analysis and observation of the morphology of each digital leaf scan. Specific and unique clone signatures appear under the observation of discernible patterns.
Aspens feature leaf dimorphism which arise from two types of leaflets, featuring short fixed shoot (stem) growth, and long free shoot growth. Short shoots can only produce embroynic early leaves, and are the very first set of leaves which appear in the spring from the winter bud. Embroyo is from the Greek embryon, “a young one”, or “one that grows at an early stage of development.” This is referred to as the spring flush. The first late leaves are also present in the winter bud, but they are arrested primordia or stopped at the beginning. Primordia comes from primus meaning ”first” and ordior “to begin”.
Lateral long shoots may produce “early” or “late” leaves. The fact that the long shoots can produce two types of leaves means that they are called heterophyllous stems or shoots. Heterophyllous meaning having two different kinds of leaves on the same stem comes from the Greek root heteros meaning “other”, and phyllon, “leaf”. Late leaves have more variety in their shape than the early leaves. Gland-tipped teeth are featured around the leaf margins on late leaves only.
A Trembling Aspen Clone leaf flush will occur at the same time because clones share the same genotype. Likewise, since the Trembling Aspen genet is all one clone, the entire genet will change colour all at once in the autumn.
Scientists have studied how to differentiate one clone of Trembling Aspens from another, and there is much discussion and preferences stated on the criteria and methods used. Hana Jelı´nkova et al have determined that finding the unique signature morphological traits to be superior to the use of spring phenology for successful analysis.
Spring phenology is more accurate than autumn phenological changes according to Michael Grant, and J.M.I. McGrath et al wrote that the phenology during spring flush showed a variety in morphology depending upon climate change variations. Both first and second leaf flushes, and their characteristics (morphology) were studied by Samuel B. St. Clair’s team. Defoliation of the leaves by insects, may require the trees to flush out a second time, as would drought and temperature extremes such as a late spring frost causing damage and defoliation of the first flush. Defoliation is to destroy or cause widespread loss of leaves.
The size and shape of leaves showed a variety between Trembling Aspen groves depending upon if the trees were in an area of elevated oxygen or Carbon Dioxide. In an interesting data collection, Reimo Lutter et al studied spring and autumn phenology on the Aspen tree from one year to the next, and found that the growing season has been lengthening.
“The timing of bud break and bud set represents events in survival and growth, discernment of these mechanisms and their interactions with climatic variables is a key to understand the consequences of the projected climate change for Populus forests”(Sivadasan, 2017). Leaf phenology has been shifting in response to earlier leaf flushing due to warm winters in relation to climate change state Yongshuo et al. Now then, Joyce G. Greene suggested that it would be wise to look at six different features to seperate Aspen clones;
- Time of leafing, and of leaf fall
- Spring and Autumn leaf colour
- Shape and Size of leaves,
- Leave serration
- Pubescence of dormant buds.”(DeByle, 1985)
Burton V. Barnes developed another set of criteria for distinguishing clones, by season and in order of usefulness.
- Stem Characteristics
- Branching habit (angle, length, and internode length)
- Susceptibility to injury
- Frost crack
- Insect and disease injury Miscellaneous
- Galls ~ Plant galls are abnormal swelling outgrowth of plant tissues caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites.
- Time of flowering, and flower characteristics
- Time, color, and rate of leaf flushing
- Leaf shape (width : length ratio), color, and size
- Shape of leaf blade base
- Leaf margin; number, size, and shape of teeth
- Shape of leaf tip
- Leaf rust infection
- Leaf color
- Time and rate of leaf fall”
Note: Pages 149-152 of Norbert V DeByle book features an appendix entitled, Wild Mammals and Birds Found in Aspen and Aspen-Conifer Mixed Forests of Western United States and Adjacent Canada.
Article copyright Julia Adamson
Use these tools to track the morphology and the phenology of the Trembling Aspens out at Richard St. Barbe Baker Afforestation Area, and in the George Genereux Urban Regional park. There is more than one Trembling Aspen stand in both the afforestation greenspaces.
A great way to engage in citizen science at the Richard St. Barbe Baker Afforestation Area, and in the George Genereux Urban Regional park is to post your images on their facebook pages!
- Is it easy or difficult to determine how the Trembling Aspen clone groves are distinct from each other in the Richard St. Barbe Baker Afforestation Area, and in the George Genereux Urban Regional park? Can this interesting experiment to study morphology and phenology in relation to clonal colonies be repeated to determine where one genet begins and another ends? How many female genets are there? How many male genets? How many Trembling Aspen groves are mixed mosaics of both female and male clones?
- What is the role of Auxin?
- Have you seen Heterophyllous long stem shoots?
- What colour is the bark of the Trembling Aspen?
- What colour is the Trembling Aspen leaf in the autumn?
- What is a catkin?
- What time of year would it be best to see a catkin – spring, summer, autumn or winter?
- What does dioecious mean?
- What is the difference between stoloniferous roots and those which are rhizomatous?
- What is an ortet, and what is a ramet? Are they related to each other?
- How do Trembling Aspens propagate?
- What colour are Trembling Aspen stigmas? What colour are Trembling Aspen anthers?
- What does plumose mean?
- What does morphology mean?
- What is phenology?
- Would you prefer to use phenology or morphology to study an Trembling Aspen stand of trees to determine if it is a mosaic, or a male clone or a female clone?
- What upsets the Trembling Aspen’s hormonal balance?
- How can studying phenology with citizen science lay the methodology for observing the effects of climate change?
Grade 1 LT1.1, Grade 3 PL3.1, Grade 6 DL6.2 ,Grade 9 RE9.3, Grade 11 ES20‐SDS1, ES20‐ES1, ES20‐TE2
Additionally, field tours are presented at the Richard St. Barbe Baker Afforestation Area and at George Genereux Urban Regional Park
Free Printed Resources are available during field tours.
Ahmad, Muhammad Salehuddin; Hasim, Nor Wahidah (2019), Plant Tissues Meristem, Scribd, retrieved May 25, 2019
Barnes, Burton V. 1969. Natural variation and delinea- tion of clones of Populus tremuloides and P. gran- didentata in northern lower Michigan. Silvae Genetica 18:130-142
Basham, J.T. (1993), Trembling Aspen Quality in Northern Ontario – Various Aspects of Decay and Stain Studies and their Management Implications (PDF), Forestry Canada. Ontario Region. Great Lakes Forestry Centre. Information Report 0-X-421, retrieved May 25, 2019
DeByle, Norbert V.; Winokur, Robert P. (August 1985), (PDF), United States Department of Agriculture Forest Service. Rocky Mountain Forest and Range Experiment Station. General Technical Report RM-119. https://www.fs.fed.us/rm/pubs_rm/rm_gtr119.pdf, retrieved May 25, 2019
Grant, M. & Mitton, J. (2010) Case Study: The Glorious, Golden, and Gigantic Quaking Aspen. Nature Education Knowledge 3(10):40
Herben, Tomáš (September 2001), Rhizome: a model of clonal grow (PDF), Department of Botany, Faculty of Science, Charles University and at the Institute of Botany, Czech Academy of Science, retrieved May 25, 2019
Hunter, Baye, Trembling aspen Peuplier faux-tremble Populus tremuloides Michx, Canadian Tree Tours, retrieved May 25, 2019
Jelı´nkova; Tremblay, Francine; DesRochers, Annie (November 15, 2013), The use of digital morphometrics and spring phenology for clone recognition in trembling aspen (populus tremuloides michx.) and its comparison to microsatellite markers, ÓSpringer-Verlag Berlin Heidelberg 2013
Lutter, Reimo; Tullus, Arvo; Tullus, Tea; Tullus, Hardi (December 2016), Spring and autumn phenology of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) genotypes of different geographic origin in hemiboreal Estonia§, New Zealand Journal of Forestry Science For. Sci. (2016) 46: 20. https://doi.org/10.1186/s40490-016-0078-7, retrieved May 25, 2019
Mayer, Amy (01 March 2010), Phenology and Citizen Science: Volunteers have documented seasonal events for more than a century, and scientific studies are benefiting from the data, BioScience, Volume 60, Issue 3, March 2010, Pages 172–175, https://doi.org/10.1525/bio.2010.60.3.3, retrieved May 25, 2019
McGrath, JMI; Karnosky, DF; Ainsworth, EA (jULY 21 2009), Spring leaf flush in aspen (Populus tremuloides) clones is altered by long-term growth at elevated carbon dioxide and elevated ozone concentration., Environ Pollut. 2010 Apr;158(4):1023-8. doi: 10.1016/j.envpol.2009.07.004. Epub 2009 Jul 21., retrieved May 25, 2019
Peltzer, Duane A (2019), Does clonal integration improve competitive ability? A test using aspen (Populus tremuloides [Salicaceae]) invasion into prairie, American Journal of Botany Volume 89, Issue 3 Botanical Society of America, retrieved May 25, 2019
Schier, George A (May 29, 1972), Origin and Development of Aspen Root Suckers, U.S.D.A. Forest Service. Intermountain and Range Experiment Station, Ogden Utah, retrieved May 25, 2019
Sivadasan, Unnikrishnan; Randriamanana, Tendry; Chenhao, Cao; Virjamo, Virpi; Nybakken, Line; Julkunen‐Tiitto, Riitta (October 7 2017), Effect of climate change on bud phenology of young aspen plants (Populus tremula. L), Ecol Evol. 2017 Oct; 7(19): 7998–8007. Published online 2017 Sep 1. doi: 10.1002/ece3.3352, retrieved May 25, 2019
St. Clair, Samuel B.; et al. (October 1, 2009), Altered leaf morphology, leaf resource dilution and defense chemistry induction in frost-defoliated aspen (Populus tremuloides), Tree Physiology, Volume 29, Issue 10, October 2009, Pages 1259–1268, https://doi.org/10.1093/treephys/tpp058 Published: 01 October 2009, retrieved May 25, 2019
Yongshuo, S.H. Fu; et al. (May 20, 2014), Effect of climate change on bud phenology of young aspen plants (Populus tremula. L), PNAS May 20, 2014 111 (20) 7355-7360; first published May 5, 2014 https://doi.org/10.1073/pnas.1321727111, retrieved May 25, 2019
SPECIES: Populus tremuloides, Fire Effects Information System (FEIS) Index of Species Information Missoula Fire Sciences Laboratory, 2018, December 4, retrieved May 25, 2019
St. Clair, Samuel B.; Monson, Steven D.; Smith, Eric A.; Cahill, David G.; Calder, William J. (October 1, 2009), Altered leaf morphology, leaf resource dilution and defense chemistry induction in frost-defoliated aspen (Populus tremuloides), Tree Physiology, Volume 29, Issue 10, October 2009, Pages 1259–1268, https://doi.org/10.1093/treephys/tpp058, retrieved May 25, 2019
“Children’s experience with the natural world seems to be overlooked to a large extent in research on child development, but it would be interesting to examine children’s early experiences with nature and follow how those experiences in nature and follow how those experiences influence the child’s long-term comfort with and respect for the natural world ~ comfort and respect…Given the power of nature to calm and soothe us in our hurried lives, it also would be interesting to study how a family’s connection to nature influences the general quality of family relationships. Speaking from my own personal experience, my own family’s relationships have been nourished over years through shared experiences in nature ~ from sharing our toddler’s wonder upon turning over a rock and discovering a magnificent bug the size of a mouse, to paddling our old canoe down a nearby creek during the children’s school years, to hiking the mountains.” ~ Martha Farrell Erickson
“Healing the broken bond between children and nature may seem to be an overwhelming, even impossible task. But we must hold the conviction that the direction of this trend can be changed, or at least slowed. The alternative to holding and acting on that belief is unthinkable for human health and for the natural environment. The environmental attachment theory is a good guiding principle: attachment to land is good for child and land.” ~ Richard Louv
For more information:
P4G Saskatoon North Partnership for Growth The P4G consists of the Cities of Saskatoon, Warman, and Martensville, the Town of Osler and the Rural Municipality of Corman Park; planning for areas around the afforestation area and West Swale outside of Saskatoon city limits
Richard St. Barbe Baker Afforestation Area is located in Saskatoon, Saskatchewan, Canada north of Cedar Villa Road, within city limits, in the furthest south west area of the city. 52° 06′ 106° 45′
Part SE 23-36-6 – Afforestation Area – 241 Township Road 362-A
Part SE 23-36-6 – SW Off-Leash Recreation Area (Richard St. Barbe Baker Afforestation Area ) – 355 Township Road 362-A
S ½ 22-36-6 Richard St. Barbe Baker Afforestation Area (West of SW OLRA) – 467 Township Road 362-A
NE 21-36-6 “George Genereux” Afforestation Area – 133 Range Road 3063
Wikimapia Map: type in Richard St. Barbe Baker Afforestation Area
Google Maps South West Off Leash area location pin at parking lot
Web page: https://stbarbebaker.wordpress.com
Where is the Richard St. Barbe Baker Afforestation Area? with map
Where is the George Genereux Urban Regional Park (Afforestation Area)? with map
Please help protect / enhance your afforestation areas, please contact the Friends of the Saskatoon Afforestation Areas Inc. (e-mail)
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“They recognize that while knowledge about nature is vital; passion is the long-distance fuel for the struggle to save what is left of our natural heritage and ~ through an emerging green urbanism ~ to reconstitute lost land and water. Passion does not arrive on videotape or on a CD; passion is personal. Passion is lifted from the earth itself by the muddy hands of the young; it travels along grass-stained sleeves to the heart. If we are going to save environmentalism and the environment, we must also save an endangered indicator species: the child in nature.”~ Richard Louv.