LA Course #GCE-1-2304
Trees For Cities
Edited by Richard W Gibney
Sections Go directly to the Section by clicking on the title below
Trees For Cities
Edited by Richard W Gibney
Sections Go directly to the Section by clicking on the title below
Note: Click on green text in each section for more information and photos.
Tried &True City Trees
Edited by Len Phillips
For the past 75 years many species and cultivars of trees that do well in our cities have been planted in cities around the world, while many other favorite trees have come and gone, and still others continue to be planted here and there. Some have become mainstream and enjoyed a 20-30 year run in popularity. However, a few species have been widely planted and successfully grown across a wide range of climates, soils, and growing conditions and are considered the “tried and true”.
Here is my personal list of the best of the “tried and true” cultivars that have become trusted urban performers for many years. These oldies but goodies have reached a stately size in many communities and are appreciated for shade, beauty and enduring character, while delivering essential environmental benefits. Many cities have recognized the value of these trees and may have over-planted some of them. If you have not planted too many of these trees, you should plan on installing more next year.
Red Sunset® Maple Acer rubrum 'Franksred'
This tried-and-true cultivar is noted for its symmetrical shape, cool summer foliage, dependably bright red autumn color and adaptability. It was selected and trialed for years prior to its introduction in 1966 by J. Frank Schmidt Jr. It was named the “Number One Shade Tree” in the Ohio Shade Tree Trials and soon became the top selling red maple in the country. Despite its many years in the marketplace, it continues to be a top seller and is among the most adaptable, resilient cultivars of the North American native species.
The deep green leaves turn bright red in mid-season, which is a timing that complements other cultivars such as the early-coloring Redpointe® and late-coloring October Glory® red maples. Install all three and enjoy 5-6 weeks of continuous autumn color. Fact Sheet
October Glory® Maple Acer rubrum 'October Glory'
Introduced in 1964 by Princeton Nurseries of New Jersey, this classic red maple is among many extraordinary trees selected by plantsman and author William Flemer III. This round-headed, extremely symmetrical selection is the last maple cultivar to color in autumn, and when it does, the color really pops. While it is less hardy than most A. rubrum cultivars, it seems to be better adapted to areas with mild winters and hot summer temperatures.
Fact Sheet
Skyline® Honeylocust Gleditsia triatanthos 'Skycole'
This is a very attractive cultivar and the most widely planted of all the honeylocusts. This “oldie but goodie” is an ideal street tree for many urban settings. Upright spreading branches create an arching canopy that provides a light, filtered shade for city streets. Small, compound leaflets create a minimum of leaf litter in autumn. Its tolerance of heat, cold, drought, soil compaction and other environmental challenges make it a versatile city tree. Skyline was selected as the “1999 Urban Tree of the Year” by a vote from the members of the Society of Municipal Arborists. This tree's popularity comes from the tree's many unique features and its ability to tolerate the urban environment. Its tolerance of various environmental challenges and excellent form make it an enduring favorite since its introduction by The Cole Nursery Co. (Ohio) in 1957. Fact Sheet
Red Oak Quercus rubra
Red Oak has been planted in cities for a century or more. This species has acquired a reputation for tolerating industrial air pollution. This particularly adaptable North American native oak thrives in diverse landscape settings across the continent. Tolerant of urban air pollution and resistant to verticillium wilt, this fast-growing, broad headed tree performs well under varied growing conditions. It is a valuable oak for lawns, parks, golf courses, commercial areas, boulevards, and other landscapes where a fast-maturing, durable and long-lived shade tree is needed. Birds and other wildlife depend on its foliage and acorns as a source of food and shelter. Its rich, dark green leaves turn to a dark red in autumn. Maturing to a size of about 50’ high x 45’ wide (15x14m), it is hardy through USDA Zone 4. Fact Sheet
Green Vase® Zelkova Zelkova serrata ‘Green Vase’
Selected and introduced by Princeton Nurseries of New Jersey in 1985, this vase-shaped selection has become the standard of comparison for Zelkova serrata cultivars. More popular and faster growing and narrower than Village Green™ Zelkova, it is appreciated for its symmetrical vase shaped, American elm-like mature form. Its height and spread at 30 years are approximately 45’ x 30’, (13 x10m). Autumn color is bright orange.
Fact Sheet
Village Green™ Zelkova Zelkova serrata 'Village Green'
Pioneering nurseryman William Flemer III foresaw the enduring value of this cultivar when he introduced it in 1964. This Princeton Nursery introduction remains popular to this day, thanks to its vigorous growth and vase-shaped canopy that reaches a height and spread of approximately 40’x40’ (12m x12m). Faster growing and narrower than the species, its mature canopy is somewhat wider and more rounded than that of Green Vase®. Dense, dark green foliage turns to rusty red in autumn. https://www.jfschmidt.com/pdfs/villagegreenzelkova.pdf
Fact Sheet
Sources:
• “Reference Guide”, J. Frank Schmidt & Son, 2022.
• Nancy Buley, “Stock Available & Nursery News”, courtesy of J. Frank Schmidt & Son Co.
• “Year of introduction for each cultivar is quoted from the Handbook of Landscape Tree Cultivars authored by
Willet N. Wandell, East Prairie Publishing Co., 2nd Edition, 1994.”
Tried &True City Trees
Edited by Len Phillips
For the past 75 years many species and cultivars of trees that do well in our cities have been planted in cities around the world, while many other favorite trees have come and gone, and still others continue to be planted here and there. Some have become mainstream and enjoyed a 20-30 year run in popularity. However, a few species have been widely planted and successfully grown across a wide range of climates, soils, and growing conditions and are considered the “tried and true”.
Here is my personal list of the best of the “tried and true” cultivars that have become trusted urban performers for many years. These oldies but goodies have reached a stately size in many communities and are appreciated for shade, beauty and enduring character, while delivering essential environmental benefits. Many cities have recognized the value of these trees and may have over-planted some of them. If you have not planted too many of these trees, you should plan on installing more next year.
Red Sunset® Maple Acer rubrum 'Franksred'
This tried-and-true cultivar is noted for its symmetrical shape, cool summer foliage, dependably bright red autumn color and adaptability. It was selected and trialed for years prior to its introduction in 1966 by J. Frank Schmidt Jr. It was named the “Number One Shade Tree” in the Ohio Shade Tree Trials and soon became the top selling red maple in the country. Despite its many years in the marketplace, it continues to be a top seller and is among the most adaptable, resilient cultivars of the North American native species.
The deep green leaves turn bright red in mid-season, which is a timing that complements other cultivars such as the early-coloring Redpointe® and late-coloring October Glory® red maples. Install all three and enjoy 5-6 weeks of continuous autumn color. Fact Sheet
October Glory® Maple Acer rubrum 'October Glory'
Introduced in 1964 by Princeton Nurseries of New Jersey, this classic red maple is among many extraordinary trees selected by plantsman and author William Flemer III. This round-headed, extremely symmetrical selection is the last maple cultivar to color in autumn, and when it does, the color really pops. While it is less hardy than most A. rubrum cultivars, it seems to be better adapted to areas with mild winters and hot summer temperatures.
Fact Sheet
Skyline® Honeylocust Gleditsia triatanthos 'Skycole'
This is a very attractive cultivar and the most widely planted of all the honeylocusts. This “oldie but goodie” is an ideal street tree for many urban settings. Upright spreading branches create an arching canopy that provides a light, filtered shade for city streets. Small, compound leaflets create a minimum of leaf litter in autumn. Its tolerance of heat, cold, drought, soil compaction and other environmental challenges make it a versatile city tree. Skyline was selected as the “1999 Urban Tree of the Year” by a vote from the members of the Society of Municipal Arborists. This tree's popularity comes from the tree's many unique features and its ability to tolerate the urban environment. Its tolerance of various environmental challenges and excellent form make it an enduring favorite since its introduction by The Cole Nursery Co. (Ohio) in 1957. Fact Sheet
Red Oak Quercus rubra
Red Oak has been planted in cities for a century or more. This species has acquired a reputation for tolerating industrial air pollution. This particularly adaptable North American native oak thrives in diverse landscape settings across the continent. Tolerant of urban air pollution and resistant to verticillium wilt, this fast-growing, broad headed tree performs well under varied growing conditions. It is a valuable oak for lawns, parks, golf courses, commercial areas, boulevards, and other landscapes where a fast-maturing, durable and long-lived shade tree is needed. Birds and other wildlife depend on its foliage and acorns as a source of food and shelter. Its rich, dark green leaves turn to a dark red in autumn. Maturing to a size of about 50’ high x 45’ wide (15x14m), it is hardy through USDA Zone 4. Fact Sheet
Green Vase® Zelkova Zelkova serrata ‘Green Vase’
Selected and introduced by Princeton Nurseries of New Jersey in 1985, this vase-shaped selection has become the standard of comparison for Zelkova serrata cultivars. More popular and faster growing and narrower than Village Green™ Zelkova, it is appreciated for its symmetrical vase shaped, American elm-like mature form. Its height and spread at 30 years are approximately 45’ x 30’, (13 x10m). Autumn color is bright orange.
Fact Sheet
Village Green™ Zelkova Zelkova serrata 'Village Green'
Pioneering nurseryman William Flemer III foresaw the enduring value of this cultivar when he introduced it in 1964. This Princeton Nursery introduction remains popular to this day, thanks to its vigorous growth and vase-shaped canopy that reaches a height and spread of approximately 40’x40’ (12m x12m). Faster growing and narrower than the species, its mature canopy is somewhat wider and more rounded than that of Green Vase®. Dense, dark green foliage turns to rusty red in autumn. https://www.jfschmidt.com/pdfs/villagegreenzelkova.pdf
Fact Sheet
Sources:
• “Reference Guide”, J. Frank Schmidt & Son, 2022.
• Nancy Buley, “Stock Available & Nursery News”, courtesy of J. Frank Schmidt & Son Co.
• “Year of introduction for each cultivar is quoted from the Handbook of Landscape Tree Cultivars authored by
Willet N. Wandell, East Prairie Publishing Co., 2nd Edition, 1994.”
Look at Paris in 2024
Edited by Len Phillips
As Paris gears up to host the 2024 Olympic Games, it also plans to give many other major tourist sights a green new look. The area around the Eiffel Tower, for example, is to be turned into an ‘extraordinary park’ just in time for the Games. The Place de la Concorde, Paris’s biggest square and the site of Marie-Antoinette’s execution, will also be planted with new trees. The suburb of Seine-Saint-Denis will soon be home to a new ‘eco-friendly’ Olympic Village, Media City, and the Olympic aquatic center. Riverside pools, built for the Games and filled with cleaned water from the Seine and then will subsequently be given over for public use.
Paris is a global icon for food, fashion and historic architecture, but its air quality is so bad that Paris ranks as one of the world’s most polluted cities. The poor air quality is from constant motor traffic, and only 9.5% of its surface is dedicated to greenery. But all of this is about to change.
Mayor Ana María "Anne" Hidalgo Aleu, first elected in 2014, has placed green policies at the forefront of her campaigns and is continuing to act on them. Paris is currently undergoing a wide-scale landscaping effort to add more gardens and green spaces to over half the city, plus hundreds of street trees are to be planted over the next five years. Paris, the “City of Light”, plans to top the chart as Europe's greenest city. To help make that happen, building codes have been loosened so it is much easier for Parisians to plant trees in their neighborhoods. Besides adding more gardens and green squares, the plan will call for a special focus on key areas, like the Champs-Élysées.
Plans are afoot to plant four new ‘urban forests’ next to major landmarks in the city. By 2026, Mayor Hidalgo has pledged to plant more than 170,000 trees across the capital, with 50 percent of the city covered with planted areas by 2030.
So far around 900 miles of bike lanes have been created across the city since Mayor Hidalgo came into office. Major roads and the docks that run alongside the River Seine in the very center of Paris, have been shut off to traffic entirely. The world-famous plazas of Madeleine, Nation and Bastille, have already been redesigned to make them more pedestrian-friendly. By 2030 all gasoline and diesel-powered cars will be banned from the city.
Much of the impetus behind such high-profile green projects stem back to a momentous international event that took place in Seine-Saint-Denis. Back in December 2015, all eyes were on the northeastern corner of the French capital as it played host to the United Nations “Conference of the Parties” (or “COP”). The talks were hailed as a turning point in the fight against climate change, with countries pledging to limit global warming to no more than 2ºC above pre-industrial levels.
The Paris Climate Conference in 2015, officially known as the 21st Conference to the United Nations Cities, (COP 21) reported that cities produce 60% of the world’s carbon emissions and use 78% of the world's energy, and they will have to play a major role in turning the Paris Agreement from a promise into a reality. So, Paris expects to be showing other cities how it’s done.
The plans stretch far beyond the 2024 Olympics. By 2030, Paris’s most famous street, the Champs-Élysées will be turned into an ‘extraordinary garden’ as part of a massive €250 million makeover. The plans include reducing the number of car lanes from four to two, creating new pedestrian and green areas, and planting ‘tree tunnels’, that improve air quality along the 5,200 ft (1.9 km) long avenue.
Perhaps most ambitiously, Mayor Hidalgo wants to reshape the way the city's two million residents interact with the city around them, with a focus on reducing car use and encouraging travel by foot, by bicycle, and by public transportation.
One of Hidalgo’s consultants is Carlos Moreno, a professor at the city’s Sorbonne University is one of the major proponents of the ‘15-minute city’ concept. In this model of the city, residents would have access to all basic services (public transportation, shops, schools, parks) within 15 minutes of their home. The COVID lock down of the past years have given many cities world-wide, pause for thought. In many cases, mayors have capitalized on the lack of foot traffic to push through drastic measures. Yet few cities anywhere in the world are acting quite as boldly and proactively as the 'City of Lights' right now. Traditionally, the two major parks to the east and west of Paris, the Bois de Vincennes and the Bois de Boulogne, have been known as ‘les poumons de Paris’: the city’s ‘lungs’. But if all goes to plan, Parisians will soon have plenty more space to breathe. The project aims to be completed by 2030.
Source
• Oliver Huw, “How Paris plans to become Europe’s greenest city by 2030”, 14 July 2021, Politics
Edited by Len Phillips
As Paris gears up to host the 2024 Olympic Games, it also plans to give many other major tourist sights a green new look. The area around the Eiffel Tower, for example, is to be turned into an ‘extraordinary park’ just in time for the Games. The Place de la Concorde, Paris’s biggest square and the site of Marie-Antoinette’s execution, will also be planted with new trees. The suburb of Seine-Saint-Denis will soon be home to a new ‘eco-friendly’ Olympic Village, Media City, and the Olympic aquatic center. Riverside pools, built for the Games and filled with cleaned water from the Seine and then will subsequently be given over for public use.
Paris is a global icon for food, fashion and historic architecture, but its air quality is so bad that Paris ranks as one of the world’s most polluted cities. The poor air quality is from constant motor traffic, and only 9.5% of its surface is dedicated to greenery. But all of this is about to change.
Mayor Ana María "Anne" Hidalgo Aleu, first elected in 2014, has placed green policies at the forefront of her campaigns and is continuing to act on them. Paris is currently undergoing a wide-scale landscaping effort to add more gardens and green spaces to over half the city, plus hundreds of street trees are to be planted over the next five years. Paris, the “City of Light”, plans to top the chart as Europe's greenest city. To help make that happen, building codes have been loosened so it is much easier for Parisians to plant trees in their neighborhoods. Besides adding more gardens and green squares, the plan will call for a special focus on key areas, like the Champs-Élysées.
Plans are afoot to plant four new ‘urban forests’ next to major landmarks in the city. By 2026, Mayor Hidalgo has pledged to plant more than 170,000 trees across the capital, with 50 percent of the city covered with planted areas by 2030.
So far around 900 miles of bike lanes have been created across the city since Mayor Hidalgo came into office. Major roads and the docks that run alongside the River Seine in the very center of Paris, have been shut off to traffic entirely. The world-famous plazas of Madeleine, Nation and Bastille, have already been redesigned to make them more pedestrian-friendly. By 2030 all gasoline and diesel-powered cars will be banned from the city.
Much of the impetus behind such high-profile green projects stem back to a momentous international event that took place in Seine-Saint-Denis. Back in December 2015, all eyes were on the northeastern corner of the French capital as it played host to the United Nations “Conference of the Parties” (or “COP”). The talks were hailed as a turning point in the fight against climate change, with countries pledging to limit global warming to no more than 2ºC above pre-industrial levels.
The Paris Climate Conference in 2015, officially known as the 21st Conference to the United Nations Cities, (COP 21) reported that cities produce 60% of the world’s carbon emissions and use 78% of the world's energy, and they will have to play a major role in turning the Paris Agreement from a promise into a reality. So, Paris expects to be showing other cities how it’s done.
The plans stretch far beyond the 2024 Olympics. By 2030, Paris’s most famous street, the Champs-Élysées will be turned into an ‘extraordinary garden’ as part of a massive €250 million makeover. The plans include reducing the number of car lanes from four to two, creating new pedestrian and green areas, and planting ‘tree tunnels’, that improve air quality along the 5,200 ft (1.9 km) long avenue.
Perhaps most ambitiously, Mayor Hidalgo wants to reshape the way the city's two million residents interact with the city around them, with a focus on reducing car use and encouraging travel by foot, by bicycle, and by public transportation.
One of Hidalgo’s consultants is Carlos Moreno, a professor at the city’s Sorbonne University is one of the major proponents of the ‘15-minute city’ concept. In this model of the city, residents would have access to all basic services (public transportation, shops, schools, parks) within 15 minutes of their home. The COVID lock down of the past years have given many cities world-wide, pause for thought. In many cases, mayors have capitalized on the lack of foot traffic to push through drastic measures. Yet few cities anywhere in the world are acting quite as boldly and proactively as the 'City of Lights' right now. Traditionally, the two major parks to the east and west of Paris, the Bois de Vincennes and the Bois de Boulogne, have been known as ‘les poumons de Paris’: the city’s ‘lungs’. But if all goes to plan, Parisians will soon have plenty more space to breathe. The project aims to be completed by 2030.
Source
• Oliver Huw, “How Paris plans to become Europe’s greenest city by 2030”, 14 July 2021, Politics
City Trees Are Better
Edited by Len Phillips
Trees may not have lungs like people, but tree tissues and soil are exchanging gases just like people breathe. Tree leaves take in air containing carbon, oxygen, pollutants, and other minor airborne elements. The carbon dioxide is used in food production by trees for photosynthesis and trees release oxygen into the air as a waste product. Trees and other plants store the carbon in their trunks, limbs and roots. Trees actually store more carbon than they release, which is great news for all the humans and animals on the planet. About 30% of carbon emissions from burning fossil fuels are absorbed by forests, in an effect called the terrestrial carbon sink. The trees are providing an incredible service to our planet.
We think about forests as big landscapes, but really, they are divided into little segments because of human activity. Forests get cut into smaller parcels, as trees are taken down to make space for roads, buildings, agriculture, etc. These alterations to the forest create areas called forest edges which are literally the trees at the outermost edge of a forest.
It has long been assumed that urban trees release and store carbon at similar rates as forest trees, but researchers have discovered this is not true. Soils and trees in urban forests and edges of large forests are acting differently than those deep in large natural forests. Two recent research papers report that city trees grow faster than their country cousins deep in the forest, and that soil in urban areas can hoard more carbon dioxide than previously thought. These results challenge current ideas about conservation and the value of urban forests as more than just places for beauty and recreation.
Using data from the US Department of Agriculture's Forest Inventory and Analysis program which monitors tree size, growth, and land use across the country, researchers found trees on the forest edges grow nearly twice as fast as interior trees. The edge includes those trees roughly 100 feet (30 m) away from the edge. This is because the trees on the edge don't have competition with interior forest trees, so they get more sunlight and water. The more a tree grows, because of more light, the more carbon it is taking in.
This is good news, considering that over 25 percent of the landscape in the Northeast United States is included within an edge. But this does not mean that more forest fragmentation is a solution for sucking more carbon out of the atmosphere. Carbon storage along the edges of fragmented areas does not come close to offsetting the negative side effects of losing forests.
This study points to the need to conserve existing forest edges, which are typically seen as more disposable. Studies have shown that even though these trees are growing faster with more sunlight, hotter temperatures are causing growth rates of edge trees to plummet.
Forest Soils
In a second study, biologists found that soils at the forest edge felt the effects of forest fragmentation, just like the trees. The soils contain wide amounts of bacteria, fungi, roots, and microorganisms, and they respire carbon dioxide, just like the trees.
Researchers found that not only does forest edge soil release more carbon than interior forest soil, but that the soil is acting dramatically different in rural versus urban forests. They saw that in rural areas with fewer people and buildings, warmer temperatures at the edge of the forest caused leaves and organic matter to decompose faster, forcing the soil microorganisms to work harder and release more carbon dioxide than their cooler, more shaded peers in the forest interior. But, in urban forests, where the ground was significantly hotter and drier, those soils stopped releasing as much carbon.
Urban forests are so hot and dry that the microbes are not happy and they're not doing their thing. The long-term effect of unhappy soil is uncertain, but the findings also mean that urban soils could have a greater capacity to store carbon than previously expected.
Although discovering that urban trees and soils store more carbon might seem like a good thing it is unclear if this boost in carbon uptake will last as the planet continues to warm. Climate change could exacerbate carbon losses from soil, and the forest.
Forests store almost half of their carbon below ground. With cities and countries making commitments to plant more trees in an effort to curb the impacts of climate change, the researchers all agree that where new trees are planted, is extremely important. Factoring in the elevated amounts of carbon stored by forest edges should be taken into account when looking at long-term projections of climate change.
Source:
Jessica Colarossi, “Sucking Carbon out of the Atmosphere”, Science Daily, Feb. 16, 2022
The test that follows contains 30 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects will award 1.0 credits for a passing grade.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/
Edited by Len Phillips
Trees may not have lungs like people, but tree tissues and soil are exchanging gases just like people breathe. Tree leaves take in air containing carbon, oxygen, pollutants, and other minor airborne elements. The carbon dioxide is used in food production by trees for photosynthesis and trees release oxygen into the air as a waste product. Trees and other plants store the carbon in their trunks, limbs and roots. Trees actually store more carbon than they release, which is great news for all the humans and animals on the planet. About 30% of carbon emissions from burning fossil fuels are absorbed by forests, in an effect called the terrestrial carbon sink. The trees are providing an incredible service to our planet.
We think about forests as big landscapes, but really, they are divided into little segments because of human activity. Forests get cut into smaller parcels, as trees are taken down to make space for roads, buildings, agriculture, etc. These alterations to the forest create areas called forest edges which are literally the trees at the outermost edge of a forest.
It has long been assumed that urban trees release and store carbon at similar rates as forest trees, but researchers have discovered this is not true. Soils and trees in urban forests and edges of large forests are acting differently than those deep in large natural forests. Two recent research papers report that city trees grow faster than their country cousins deep in the forest, and that soil in urban areas can hoard more carbon dioxide than previously thought. These results challenge current ideas about conservation and the value of urban forests as more than just places for beauty and recreation.
Using data from the US Department of Agriculture's Forest Inventory and Analysis program which monitors tree size, growth, and land use across the country, researchers found trees on the forest edges grow nearly twice as fast as interior trees. The edge includes those trees roughly 100 feet (30 m) away from the edge. This is because the trees on the edge don't have competition with interior forest trees, so they get more sunlight and water. The more a tree grows, because of more light, the more carbon it is taking in.
This is good news, considering that over 25 percent of the landscape in the Northeast United States is included within an edge. But this does not mean that more forest fragmentation is a solution for sucking more carbon out of the atmosphere. Carbon storage along the edges of fragmented areas does not come close to offsetting the negative side effects of losing forests.
This study points to the need to conserve existing forest edges, which are typically seen as more disposable. Studies have shown that even though these trees are growing faster with more sunlight, hotter temperatures are causing growth rates of edge trees to plummet.
Forest Soils
In a second study, biologists found that soils at the forest edge felt the effects of forest fragmentation, just like the trees. The soils contain wide amounts of bacteria, fungi, roots, and microorganisms, and they respire carbon dioxide, just like the trees.
Researchers found that not only does forest edge soil release more carbon than interior forest soil, but that the soil is acting dramatically different in rural versus urban forests. They saw that in rural areas with fewer people and buildings, warmer temperatures at the edge of the forest caused leaves and organic matter to decompose faster, forcing the soil microorganisms to work harder and release more carbon dioxide than their cooler, more shaded peers in the forest interior. But, in urban forests, where the ground was significantly hotter and drier, those soils stopped releasing as much carbon.
Urban forests are so hot and dry that the microbes are not happy and they're not doing their thing. The long-term effect of unhappy soil is uncertain, but the findings also mean that urban soils could have a greater capacity to store carbon than previously expected.
Although discovering that urban trees and soils store more carbon might seem like a good thing it is unclear if this boost in carbon uptake will last as the planet continues to warm. Climate change could exacerbate carbon losses from soil, and the forest.
Forests store almost half of their carbon below ground. With cities and countries making commitments to plant more trees in an effort to curb the impacts of climate change, the researchers all agree that where new trees are planted, is extremely important. Factoring in the elevated amounts of carbon stored by forest edges should be taken into account when looking at long-term projections of climate change.
Source:
Jessica Colarossi, “Sucking Carbon out of the Atmosphere”, Science Daily, Feb. 16, 2022
The test that follows contains 30 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
LA CES will award 1.0 PDH (HSW) credit for a passing grade. North Carolina Board of LA and New Jersey Board of Architects will award 1.0 credits for a passing grade.
The cost for taking this test is $20 per credit. If you purchase an annual subscription for 12 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report your passing test score to LA CES. If you are also ISA* certified we will report your passing score to ISA for no additional cost. Please be sure to add your ISA Certification number when you sign in. Tests with passing scores may be submitted only once to each organization.
*ISA has approved this course for .5 CEUs per section for a total of 1.5 CEUs.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. If you are an ISA and/or CLARB member, please be sure to include your certification/member number(s) along with your LA license and ASLA numbers.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks after that.
LA CES maintains a record of earned PDH credits on their website http://laces.asla.org/
ISA maintains a record of earned CEU credits on their website http://www.isa-arbor.com/