Pinus ponderosa (Ponderosa pine)

Guess what folks? It’s finals week so I’m very stressed, low on sleep, heavily caffeinated, and still determined to make a weekly blog post so here we are. Continuing in sharing my class notes from Dendrology, I thought I’d post the latest paper I wrote on the subject (plus a fun info graphic) profiling one of my favorite trees the Ponderosa pine. Hope you enjoy and learn something new!

Silvics of Ponderosa pine Pinus ponderosa (Dougl. ex. Laws) Pinaceae and Quaking Aspen Populus tremuloides (Michx.) Salicaceae

Photos are and design are my own, center sketch is from Matt Strieby 2021

Ponderosa pine Pinus ponderosa (Dougl. ex. Laws) Pinaceae

Morphology: Pinus ponderosa is most commonly known as ponderosa pine or western yellow pine.The trees are identifiable by their brown to black deeply furrowed bark that turns cinnamon and yellow brown with age as it starts flaking off in scales and the furrows look more like plates. The crown is pyramidal to flat while the needles are normally in clusters of (two or) three, gray green to dark yellow in color, and 3-6 inches in length. The cones are produced irregularly and are circular with sharp points at the ends of the scales. The trees can grow for up to 600 years with a diameter of 30-50 inches and heights of up to150-180 feet (Burns and Honkala 1990A).

Habitat: Ponderosa pines are shade intolerant and soil moisture is often the most limiting variable for growth, but they can handle average temperatures from 5˚ to 21˚C (41˚-70˚F) comfortably and extremes of -40˚ to 43˚C (-40˚ to 110˚F). (Silvics 1) These trees can live in a wide range of topographic and soil complexes including more dry sites, areas with coarser textured soils, a range of pH (4.9 to 9.1), and can grow in low nitrogen and phosphorus areas. These trees are found from sea elevations up to 3050 meters (Burns and Honkala 1990A).

Range: Ponderosa pines are disturbed across western North America and have one of the most extensive ranges of pines in the United States as they reach from Mexico into southern Canada and from the Plains to the Pacific coast. Two varieties are recognized, P. ponderosa var. ponderosa (Pacific) and var. scopulorum (Rocky Mountain) based on regional differences (Burns and Honkala 1990A).

Ecology: Pinus ponderosa has a wide range of associated species included but not limited to: Pseudotsuga menzisii, Larix occcienatlis, Abies concolor, Pinus jeffreyi, Quercus kelloggii, Picea glauca, Populus tremuloides, Betula papyrifera, Arctostaphylos, Ceanothus, Purshia, Artemisia, Rosa, Prunus, Spiraea, Symphoricarpos, Physocarpus, Agropyron, Andropogon, Bouteloua, Festuca, and Poa. The “community composition varies widely with geographic location, soils, elevation, aspect, and successional status” leading to a wide range of associates in P. ponderosa forests (Burns and Honkala 1990A). One study by Abella and Covington analyzed environmental and geological variables to determine how community composition in Pinus ponderosa forests is paralleled geological gradients in soil texture, water, C and N composition, and precipitation patterns (2006). The researchers modeled species and soil composition and found that the parent soil material based on volcanic activity is a major factor in constraining vegetation patterns. They also discovered the most rapid diameter growth of P. ponderosa occurred in areas with high Festuca and Lathyrus groups and better growth was correlated with moister, loam and silt-loam soils (Abella and Covington 2006).

Wildlife interactions: Animals uses these trees and the forests made up of them as habitat— especially squirrels, deer, and elk. Unfortunately the trees are harmed by grazing and insect attacks, especially by varieties of Dendroctonus spp. or bark beetles (Burns and Honkala 1990A).

Ethnobotany: Humans use ponderosa pines as a major source of timber. Forests comprised of these trees are important for recreation uses and aesthetic values (Burns and Honkala 1990A). The indigenous groups of North America eat Ponderosa pine seeds raw and use the inner bark as food or steep/boiled for tea (Savage 2019). The wood can be used for lodge poles and travois runners, or made into ceremonial whistles and flutes. The pitch is used to keep hair in place and the gum from the tree works as a salve for sores and scabs. Resin can be used as chewing gum, fire starter, or even as a yellow dye while the roots are used to make a blue dye (Savage 2019).

Quaking Aspen Populus tremuloides (Michx.) Salicaceae

Morphology: Populus tremulodies is also known as Quaking aspen, trembling aspen, golden aspen, Mountain aspen, and trembling poplar (Burns and Honkala 1990B). A deciduous tree, it typically grows less than 15 meters high and with a max of 40 centimeters in diameter. The bark is white to gray green with a smooth, slightly glaucous appearance. The leaves are alternate and ovate to orb shaped with flattened petioles and turn a brilliant yellow in the fall. The trees grow in single to multi stemmed colonies. They are primarily dioecious, with catkins and tufted capsules bearing seeds in April to June depending on climate. Quaking aspens can reproduce vegetatively via asexually root suckering which can result in large colonial tree groves that are genetically identical (Burns and Honkala 1990B).

Habitat: Quaking aspens are fast growing pioneers that are quick to grow on disturbed sites (Burns and Honkala 1990B). They can handle a wide range of soil characteristics, climatic conditions, elevation gradients, temperatures, and precipitation. Aspens can grow at sea level up to 3500 meters and grows best in favorable moist conditions and well drained soils (Burns and Honkala 1990B).

Range: P. tremulodies is the most widely disturbed tree in North America ranging from Newfoundland in Canada out west to upper Alaska and down throughout the United States in Southern Arizona into Mexico and up the eastern seaboard (Burns and Honkala 1990B).

Ecology: There are many associated species of aspen depending on location and climate. Some associated including but not limited to: Corylus, Acer, Alnus, Rubus, Ribes, Salix, Symphoricarpos, Lonicera, Cornus, Amelanchier, Prunus, Rosa, Shepherdia, Vaccinium, Juniperus communis, Berberis repens, Sambucus, Aster, Aralia, Maianthemum, Clintonia, Galium, Athyrium , Pteridium, Carex, and Solidago (Burns and Honkala 1990B). P. tremulodies is short lived and often is gradually replaced by slower-growing species (Burns and Honkala 1990B). Yet due to the asexual reproductive habits of these trees, giant clonal colonies can exist for thousands of years. The largest organism in the world is “Pando”, a 43.6 ha (108 acre) aspen grove composed of genetically identical trees in Utah that is estimated to be thousands of years old. A study by Romme et al. looked at the many genetically identical stems (ramets) of P. tremulodies arise from a common root system and while sprouting via seeds is rare in the Rocky Mountains, sexual reproduction has occurred (2005). Following the extensive 1988 fires in Yellowstone, the researchers used surveys and experiments to investigate genet establishment, growth, and survival rates over their initial ten years. After aging almost 200 aspen stems in 1996 they found that “65% had established within the first three years after the 1988 fires, and that none predated 1988” while DNA sequencing showed “92% of the plants were genetically distinct individuals, and 8% were ramets” (Romme et al 2005). They also tested mortality of aspen seedlings and found rates varied greatly but was highest in plots at low elevations with poor soils (Romme et al 2005).

Wildlife interactions: Quaking aspen provides habitat and food for many wildlife species including rabbits, bears, deer elk, grouse, and other smaller birds and animals. Ruffled grouse use aspen stands of all ages for brooding, “pole stands for overwintering and breeding, and older stands for nesting cover and winter food” (Burns and Honkala 1990B).

Ethnobotany: Quaking aspen’s light, soft wood (high grade) is used for lumber and to make matches while (low grade) aspen wood is turned into pulp and flake-board (Burns and Honkala 1990B). Other wood products include studs, veneer, plywood, excelsior, shingles, novelty items, wood flour, and sheets are turned into sauna benches or playground structures due to the flexibility of the wood (Burns and Honkala 1990B). P. tremulodies is used by indigenous groups via infusions from the bark to help with childbirth, leaves or saplings as forage for horses, the wood is used for construction, the downy seeds as pillow fill, and various parts have ceremonial meanings (Savage 2019) The most notable medicinal uses are crushing the aspen’s leaves, stems, roots, and bark to create a poultice that is applied to stings and minor wounds (Westhaver 2018) . A decoction of the bark and stems was used by a variety of indigenous groups as a treatment for cramps, parasitic infections, gonorrhea, and other diseases (Westhaver 2018).

Pinus ponderosa and Populus tremulodies interactions: These two species have large range overlaps and are often found growing together. For the most part they coexist peacefully, but quaking aspen stands can inadvertently harm ponderosa pine as aspens are non-host angiosperms that can harbor the deadly (to trees) western pine beetle that loves to munch on ponderosas. A study by Shepherd et al looked at stem volatile extracts from ten trees sympatric with the western pine beetle, Dendroctonus brevicomis 2008). The primary host of this beetle is Pinus podnerosa, which the researchers analyzed against two non host angiosperms, Quercus kelloggii and Populus tremuloides along with seven nonhost conifers: Abies concolor, Calocedrus decurrens, Pinus contorta murrayana, P. jeffreyi, P. lambertiana, Pseudotsuga menziesii, and Tsuga mertensiana. They identified 64 compounds, 42 which elicited antennal responses in D. brevicomis. Of the active compounds only geraniol was unique to Pinus ponderosa and other compoudns like conophthorin was identified from both nonhost angiosperms as well as ponderosa pine (Shepherd et al 2008). These trees can also effect other plants in the forest. Ponderosa pines and quaking aspen can both effect the soil properties including mineral and organic matter composition of an area and can lead to a change in the level of cover and of richness in understory plant species In both cases, higher over-story density (more so in ponderosa pines) can lead to a decrease in understory species diversity (Laughlin et al 2007).

The reader is encouraged to go outside to see these trees in person to gain a better understanding of the beauty of the forests comprised of these trees, how they grow together, what animals can be found beneath their branches, and what other wonders await. It is highly encouraged to find a good grove and to stop and listen to the leaves of the quaking aspen musically trembling in the wind or to look up and admire the beauty of the ponderosa pines standing tall.

Works cited:

Abella, Scott R. and W. Wallace Covington. 2006. Vegetation –environment relationships and ecological species groups of an Arizona Pinus ponderosa landscape, USA. Plant Ecology 185: 255-268

Burns,Russell M.,and Barbara H. Honkala 1990A. Silvics of North America: 1. Conifers. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington,DC.vol.1

Burns, Russell M., and Barbara H. Honkala. 1990B. Silvics of North America: 2. Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, DC. vol. 2

Laughlin, Daniel C.; Abella, Scott R.; Covington, W. Wallace1 & Grace, James B. 2007. Species richness and soil properties in Pinus ponderosa forests: A structural equation modeling analysis. Journal of Vegetation Science 19: 231-242

Romme, Willam H. Monica G. Turner, Gerald A. Tuscan, and Rebecca A. Reed. 2005 “ESTABLISHMENT, PERSISTENCE, AND GROWTH OF ASPEN (POPULUS TREMULOIDES) SEEDLINGS IN YELLOWSTONE NATIONAL PARK” Ecology 86 (2) 404-418.

Savage, Meredith. 2019. An Ethnobotany of Mount Rushmore National Memorial. University of Massachusetts Amherst: Landscape Architecture & Regional Planning Masters Projects 92

Shepherd, William P.; Dezene P. W. Huber, Steven J. Seybold, and Christopher J. Getting. 2008. “Antennal responses of the western pine beetle, Dendroctonus brevicomis (Coleoptera: Curculionidae), to stem volatiles of its primary host, Pinus ponderosa, and nine sympatric nonhost angiosperms and conifers” Chemoecology 17: 209-221

Westhaver, A.R., 2018. Populus tremuloides Michx.| trembling aspen| qw'i'qw'iyulushulhp. Logan Creek Decolonization Project Journal, 1(1), pp.20-23.