Got Nature? Blog

When you hear about endangered species, most of us think about the plights of our furry or feathered friends. This article describes the plight of some of the less cuddly members of the endangered species list. Indiana is home to a number of endangered and threatened tree species. In this multi-part series, we will identify some of the tree species and describe some of their unique characteristics.

Our first species is the American chestnut (Castanea dentata) sometimes called the “Sequoia of the East”. This species was once found thriving throughout eastern forests from central Maine west to southeastern Michigan, and south to northern Mississippi, Alabama, and Georgia.

Early 20^th century estimates indicated that these trees numbered closed to 4 billion with the finest, most productive stands found in the Appalachian Mountains and southern New England. American chestnut is a fast growing species that can reach a pinnacle of 120 feet high and 10 feet or more in diameter. The majority of the mature trees were between 3 and 5 feet in diameter and 60 to 90 feet high. The fruit from this tree has been a valued food source for humans, wildlife, and livestock alike. Timber from this former giant is naturally rot-resistant and nearly as durable as oak yet lighter.

American chestnut populations went into decline after the introduction of chestnut blight.

Chestnut blight is caused by the fungal pathogen (Cryphonectria parasitica), and was accidentally introduced into the American population by imported Asian chestnut trees a century ago. American chestnut is highly susceptible to the fungus which enters the tree through any small wound or crack in the bark. The fungus replicates beneath the bark and produces toxins which lead to plant cell death. The fungus continues to grow until it has circumnavigated the tree and effectively stopped the flow of nutrients. Everything above the girdled circle of fungus will die. The primary symptoms of chestnut blight disease are a sunken canker and orange spores covering the bark.

Loss of American chestnut on the landscape has resulted in reduced species diversity and severely reduced fall mast for woodland animal species. In addition, leaves of American chestnut contain greater nutrient concentrations (nitrogen [N], phosphorus [P], potassium [K]) than most other co-occurring trees therefore its loss affects soil nutrient cycling.

American chestnut has survived thus far because it has the ability to sprout from roots and stumps of diseased trees. However, these trees rarely live to maturity thus are often unable to flower and bear fruit. Numerous efforts to restore the tree to its former glory have been and are currently being attempted. Thus far, two of the most effective methods of breeding for resistance are hybridizing with resistant Asian parents and attempting to intercross surviving pure American chestnuts. The HTIRC within the Forestry and Natural Resources Department at Purdue University is working on hybridization of American chestnuts with Asian chestnuts for future restoration of resistant American-like chestnuts for Indiana.

Resources:
The American Chestnut Foundation
A New Generation of American chestnut Trees May Redefine America’s Forests – Scientific American
Consequences of Shifts in Abundance and Distribution of American Chestnut for Restoration of a Foundation Forest Tree – Forests Open Access Forestry Journal
Transgenic American chestnuts show enhanced blight resistance and transmit the trait to T1 progeny – Science Direct (Plant Science)
Scientists Work to Create a Blight-Resistant Chestnut with Hopes of Restoring Tree to America, Forest Service, U.S. Department of Agriculture
FNR Hardwood – American Chestnut, Purdue Arboretum Explorer
Hardwood Tree Improvement Regeneration Center (HTIRC) Research Publications
American Chestnut Trees return to the Hoosier National Forest, Indiana Woodland Steward
Forest Regeneration and Restoration Laboratory, Purdue Forestry and Natural Resources, Dr. Doug Jacobs

Shaneka Lawson, USDA Forest Service and HTIRC Research Plant Physiologist & Adjunct Assistant Professor
Purdue University Department of Forestry and Natural Resources

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Learn how forests are used by birds and how best practices in forest management can increase their numbers in these newly released videos on birds and their relationship with woodlands.

In the first video, “Managing Woodlands for Birds,” J. Barny Dunning, professor of wildlife ecology, discusses how forests are used by birds year round, important habitat features of woodlands that can benefit birds, and how woodland owners can enhance their property for birds. In the second video, “Hardwood Ecosystem Experiment – Forest Birds,” Professor Dunning and graduate student Patrick Ruhl cover how disturbance and forest management impact birds. Management recommendations for both videos were developed in part from the Hardwood Ecosystem Experiment, a long-term, large-scale experimental study of forest management and its impacts on plants and animals.

Check out “Managing Woodlands for Birds” and “Hardwood Ecosystem Experiment – Forest Birds” to learn more about how birds use forests and how we can impact them in a positive way. To learn more about the Hardwood Ecosystem Experiment, please visit the HEE website.

Resources:
Managing Woodlands for Birds – YouTube, Purdue Extension Resource Center
Hardwood Ecosystem Experiment – Forest Birds – The Education Store
Breeding Birds and Forest Management: the Hardwood Ecosystem Experiment and the Central Hardwoods Region – The Education Store
The Hardwood Ecosystem Experiment: Indiana Forestry and Wildlife – The Education Store

J. Barny Dunning, Professor of Wildlife Ecology
Purdue University Department of Forestry and Natural Resources

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​Urban Forestry Specialist Lindsey Purcell‘s helpful publication “Tree Pruning Essentials” is now available in a Spanish-language version, “Lo Esencial Para la Poda de Árboles.” This publication explores the techniques behind good pruning, from the planning process before planting to monitoring the tree’s response after the pruning cuts.

Trees continue to survive in spite of the many challenges they face in the urban environment. However, to grow from seedling to a mature tree in the urban forest, they need our help. They are the largest, oldest living organisms on the planet and can live long, healthy lives with some assistance. We often place trees in less-than-favorable growing locations that don’t allow natural development and maturity and often require pruning to develop a durable structure, improve clearance and maintain aesthetics.

Pruning has been called “one of the best, worst maintenance practices” performed on trees. The process creates wounds, which have a major impact on plant processes. Improper cutting on a tree causes severe damage or even death. To prune properly, it is important to understand both the proper techniques and how the tree responds to pruning.

Check out “Lo Esencial Para la Poda de Árboles” or “Tree Pruning Essentials” and make sure you are pruning your trees to maximize safety, aesthetics, and tree health!

Resources:
Lo Esencial Para la Poda de Árboles (Tree Pruning Essentials)– The Education Store, Purdue Extension Resource Center
Instalación de Árboles: Proceso y practicas (Tree Installation) – The Education Store, Purdue Extension Resource Center
Tree Pruning Essentials – The Education Store
Trees and Storms: Understanding Damage, Risk and Recovery – Got Nature? Blog, Purdue Extension – FNR
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Prune Your Trees​ – Indiana Department of Natural Resources

Lindsey Purcell, Urban Forestry Specialist
Purdue University Department of Forestry and Natural Resources

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Question: I am noticing pine trees dying in my neighbors’ yards and along the streets in Carmel and NE Indianapolis. The needles turn rust colored and fall within a couple weeks – leaving a bare tree. Some of these trees are mature but most are young. Should I be concerned? What should I do to protect my pine trees? What should I be looking for if it is a pest?

Answer: Many Indiana trees are dying from stress caused by the extreme weather we have had in the last few years. Urban Forestry Specialist Lindsey Purcell and Extension Consumer Horticulture Specialist Rosie Lerner discuss this in more detail in the Purdue Agriculture News article “Purdue experts: Tree deaths across Indiana may be related to weather stress.” There are also other potential causes of foliar discoloration and branch dieback in pine trees that are explained in the publication “Stress-related Conifer Dieback“.

If you’d like to investigate the issue further, a certified arborist​ can conduct a ground evaluation or you can examine the trees on your own using the Purdue Tree Doctor app.

Resources:
Purdue experts: Tree deaths across Indiana may be related to weather stress – Purdue Agriculture News
Stress-related Conifer Dieback – The Education Store, Purdue Extension Resource Center
Purdue Plant Doctor App – Purdue Botany and Plant Pathology and Extension Entomology
Needle cast in Colorado Blue Spruce, Purdue Landscape Report
Blue Spruce Update, Purdue Landscape Report
Why Spruce Trees Lose Their Needles, Purdue Extension
Blue Spruce Decline, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension
Tree Installation: Process and Practices, The Education Store, Purdue Extension resource center
Tree Planting and Urban Forestry Videos, Subscribe to our Purdue Extension-FNR YouTube Channel
Find an Arborist, International Society of Arboriculture

Lenny Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources

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​Since 2010, farmers in the Indian Creek watershed in Illinois have been working together to implement conservation practices and nutrient management strategies to reduce nutrient loading in Indian Creek. Postdoctoral Research Associate Sarah Church led the process of evaluating this watershed project and understanding which social conditions contributed to the project’s success. Her findings are presented in this new publication “Indian Creek Watershed Project: Key Takeaways for Success.”

In continuing sharing the research regarding the issues of Indian Creek Purdue Extension’s Aaron Doenges produced two videos. These videos focus on two key reasons for the project’s success: the people involved with the project’s steering committee; and the partnerships formed with agribusinesses.

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Your real tree, once cut, is like fresh fruit in regards to its useful life expectancy. Just like fruit, care needs to be exercised in the trees selection and subsequent care according to Daniel Cassens, Professor in the Department of Forestry and Natural Resources, Purdue University and member of the National Christmas Tree Association. Over half of the tree’s weight consists of water when first cut and it is important that the water content be maintained.

First, it is important to select a fresh tree. If you cut the tree at a choose-and-cut farm, it has to be fresh. If the tree is pre-cut, make sure the needles are flexible and firmly attached to the stem. Also, the tree should look “normal” and not crushed with broken branches and distorted or missing needles. Fresh looking trees indicate they have been well cared for.

Fresh cut trees should be kept out of the sun and wind to prevent accelerated dehydration. If the tree needs to be temporarily stored, place it in an unheated building or on the north side of a building where it will be less exposed. It will also help to place the tree in a bucket of water.

Just before setting up the tree, using an inexpensive bow or other saw trim about one-half inch from the base of the trunk. The cut should be perpendicular to the main stem. If the tree cannot be set up within 6 to 8 hours, make another cut. About 6 to 8 hours after the cut is made, the living cells begin to die and become blocked so the tree cannot take up water.

The tree should now be placed in a stand capable of supporting the tree mechanically. Make sure the stand has extended legs to prevent the tree from tipping. Do not whittle down the outside diameter of the tree base. The outer layers of wood are the most effective in taking up water. The stand should also be able to hold at least one quart of water for each inch of stem diameter. A typical 7 foot tree will require a stand with a water holding capacity of about two gallons. Check the water level each day and add cool water as needed. Make sure the butt end of the tree stem is always in water contact. Some stands do not allow the stem to reach the bottom of the water holding container. Trees tend to take large quantities of water each day for the first week or so and then slow down. Remember, if the tree runs out of water, the cells in the very butt or exposed end will become blocked and subsequent water uptake will be prevented.

Some tree lights can also produce excessive heat. Small lights or those that produce low heat will also help to reducing localized drying of the tree.

For more information about Christmas trees or to locate a choose-and-cut tree farm near you, please visit the National Christmas Tree Growers Association.

Resources:
A Choose-and-Cut Pine and Fir Christmas Tree Case Study, The Education Store, Purdue Extension’s resource center
Selecting an Indiana-Grown Christmas Tree, The Education Store
Tips for First-Time Buyers of Real Christmas Trees, The Education Store

Daniel Cassens, Professor Emeritus
Department of Forestry and Natural Resources

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The debate over rather the use of a real tree or an artificial tree is better for the environment continues, especially as the Holiday season nears. Real tree growers point out that their product is renewable, each species has its own characteristic odor, consumes carbon dioxide and gives off oxygen, can be recycled, provides wildlife habitat and creates jobs in rural America. Artificial trees contain non biodegradable plastics and possible metal toxins such as lead. Most artificial trees are made in China and must be shipped long distances to the United States. On the other hand the artificial tree industry points out that their product can be reused and thus saves several real trees from being harvested. The industry goes on to claim that their trees do not need fertilizers or pesticides and do not create a mess or hassle. These are just examples of claims being made by two distinctly different industries. Considering the entire production cycle for real and artificial trees, it is difficult to determine which type of tree is best for the environment, based on scientific based data. Conducting a “Life Cycle Assessment” (LCA) for real and artificial trees would be one approach to answer this question.

Real Christmas trees, like all green plants, consume carbon dioxide and produce oxygen. The carbon dioxide is absorbed through the leaves or needles, combined with sunshine and water to make food and release oxygen. This process is called photosynthesis. The “carbon” is stored in the wood, needles, and leaves and constitutes about one-half of the dry weight. If the trees are burned or otherwise decomposed the “stored” or sequestered carbon is released back into the atmosphere. Other existing or planted trees absorb the carbon making trees carbon neutral. Some of the carbon is also stored in the soil. Growing trees also require some carbon dioxide back into the atmosphere.

Artificial trees use petroleum based products. Petroleum based products are ancient, stored sources of carbon dioxide and if burned as in the case of gasoline, release new carbon dioxide into the atmosphere. Transportation becomes a significant source of carbon release regardless of the tree being real or artificial.

Carbon dioxide is important because it traps heat from the earth’s surface. This is often referred to as the “greenhouse effect”. The amount of carbon dioxide in the atmosphere has been increasing since the late 1800’s and scientific data shows a particularly significant increase since the 1960’s. “Global warming” is the term being used to describe an increase in the world’s average surface temperature as a result of more heat being trapped.

“Cradle to Grave” or “Life Cycle Assessments” are used to summarize all of the positive and negative activities associated with developing a product and delivering it to the consumer. LCA’s become complicated, costly and the results are dependent on exactly which set or sets of circumstances are considered. Only one documented study on real and artificial trees is available. A Canadian Environmental consulting firm, Ellipsos has completed a LCA for both real and artificial trees. (Ellipsos/Strategists in Sustainable Development)

In this study, the carbon balance for an individual 7 foot high real Christmas tree was about +24 Kg (53 lbs) of CARBON DIOXIDE after all factors such as labor, use of machinery, transportation, and other inputs are considered. The tree was grown south of Montreal, Canada. It was assumed that the tree was grown in the nursery for four years and in the field for 11 years. In Indiana, two year old nursery stock and about 7 years in the field to produce a 7 foot tree are more typical and would probably result in less carbon being released. The “+” indicates that the overall process of growing a tree is carbon positive (i.e. carbon is released).

The carbon balance for a similar six foot artificial tree was about +48Kg (106 lbs) of CARBON DIOXIDE or twice that of the real tree. Most of the positive carbon release in this case is due to the manufacturing of the tree and transportation of the tree by boat from China to Vancouver and then by train to Montreal, Canada.

For comparison purposes, the average American car emits about 1.5 tons or 3000 pounds of carbon into the atmosphere on a yearly basis. (Green Car Congress)

The Ellipsos report assumed that the real tree would be burned for fuel at the end of the life cycle, thus releasing all of the stored carbon in the tree. If the real tree is recycled for mulch or fish habitat or other uses the carbon budget would be closer to zero at least until the tree finally decomposes. The study goes on to conclude that considering climate change impact along with environmental and public health impact, real trees appear to be a better choice for a responsible customer and that artificial trees must be displayed for more than 20 years in order for it to compare favorably with the real Christmas tree.

The assessment method used for the life cycle analysis groups problems into four damage oriented impacts areas on the environment. These are 1) climate change, 2) human health, 3) ecosystem quality, and 4) resource depletion. The results for the Ellipsos report are interesting. Considering climate change, the real tree has much less impact due to a smaller amount of carbon being released into the atmosphere as discussed above. The LCA also considers the products impact on human health, ecosystem quality and resource depletion. Considering human health, the artificial tree is a slightly better choice than the real tree. Considering ecosystem quality, the artificial tree is a better choice. This is likely due to the use of land for plantations and associated cultural practices (fertilizer, pesticide, irrigation) for real trees. In regards to both climate change (global warming) and resource depletion (use of non-renewable energy and mineral extraction), the real tree is a better choice than the artificial tree. The Ellipsos report titled “Comparative life Cycle Assessment (LCA) of Artificial vs Natural Christmas trees” can be viewed by Googling “Ellipsos report 1043-RF3-09.”

Both real and artificial trees have positive and negative attributes. Based on this study, the real tree has less effect on global warming than the artificial tree ie less carbon is released. The amount of carbon released by either the real or artificial tree is relatively small compared to that released by the average car over the course of the year. To reduce carbon production, consumers might be better advised to limit (plan ahead) the use of the car over the holiday season.

For more information about Christmas trees or to locate a choose-and-cut tree farm near you, please visit the National Christmas Tree Growers Association.

Other resources:
A Choose-and-Cut Pine and Fir Christmas Tree Case Study, The Education Store, Purdue Extension’s resource center
Selecting an Indiana-Grown Christmas Tree, The Education Store
Tips for First-Time Buyers of Real Christmas Trees, The Education Store

Daniel Cassens, Professor Emeritus
Department of Forestry and Natural Resources

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