By Rabiu O. Olatinwo, Stephen W. Fraedrich and Albert E. Mayfield III
In recent years, outbreaks of nonnative invasive insects and pathogens have caused significant levels of tree mortality and disturbance in various forest ecosystems throughout the United States. Laurel wilt, caused by the pathogen Raffaelea lauricola (T.C. Harr., Fraedrich and Aghayeva) and the primary vector, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff), is a nonnative pest-disease complex first reported in the southeastern United States in 2002. Since then, it has spread across eleven southeastern states to date, killing hundreds of millions of trees in the plant family Lauraceae. Here, we examine the impacts of laurel wilt on selected vulnerable Lauraceae in the United States and discuss management methods for limiting geographic expansion and reducing impact. Although about 13 species belonging to the Lauraceae are indigenous to the United States, the highly susceptible members of the family to laurel wilt are the large tree species including redbay (Persea borbonia (L.) Spreng) and sassafras (Sassafras albidum (Nutt.) Nees), with a significant economic impact on the commercial production of avocado (Persea americana Mill.), an important species native to Central America grown in the United States. Preventing new introductions and mitigating the impact of previously introduced nonnative species are critically important to decelerate losses of forest habitat, genetic diversity, and overall ecosystem value.
Hayes, Deborah C.; Kerns, Becky K.; Patel-Weynand, Toral; Finch, Deborah M. . 2021. Introduction. In: Poland, Therese M.; Patel-Weynand, Toral; Finch, Deborah M.; Ford Miniat, Chelcy; Hayes, Deborah C.; Lopez, Vanessa M., eds. Invasive Species in Forests and Rangelands of the United States: A Comprehensive Science Synthesis for the United States Forest Sector. Heidelberg, Germany: Springer International Publishing: 1-4. https://doi.org/10.1007/978-3-030-45367-1_1.
Invasive species are a historical, long-term, and continually growing threat to the ecology, economy, and infrastructure of the United States. Widely recognized as one of the most serious threats to the health, sustainability, and productivity of native ecosystems, invasive species issues have commonly been viewed as problems specific to Federal, State, and private landowners. However, it is increasingly apparent that the impacts from these species are all encompassing, affecting ecosystem processes in addition to the economics of land management, public and private infrastructure, the energy sector, international trade, cultural practices, and many other sectors in the United States.
By Rachel Cernansky
After returning home from college to northwest Cameroon in 2004, Tabi Joda felt a sense of profound loss. Trees that once bore fruit, provided medicine, and created shade had been cut down. Rich soils had turned to dust. “The land I used to know as a forest was no longer a forest,” he recalls. Joda, a business consultant, got to work, calling on what he’d learned in school and from local knowledge passed down over generations. He collected seeds, started a tree nursery, and launched an agroforestry initiative that enlisted local people in planting trees. They chose species that provided food and timber, supported livelihoods, and helped wildlife thrive. The effort soon spread to nearby communities. And Joda ultimately became a vocal advocate for an even bigger dream: the Great Green Wall, which aims to transform the lives of some 100 million people by planting a mosaic of trees, shrubs, and grasses along a corridor stretching some 8000 kilometers across Africa by 2030.
Since the African Union first launched the Great Green Wall in 2007, the initiative has struggled to make headway. Made up of local efforts across 11 countries, it has reached just 16% of its overall goal to vegetate 150 million hectares. But last month, the project—which analysts estimate will cost at least $30 billion—got a major boost: a pledge of $14 billion in funding over the next 5 years from a coalition of international development banks and governments. The money is meant to accelerate the effort to sustain livelihoods, conserve biodiversity, and combat desertification and climate change, French President Emmanuel Macron said in announcing the pledges on 11 January.
Environmental restoration and community development specialists welcomed the news. But many are also apprehensive. In recent years, research by ecologists, economists, and social scientists has shown that many forestry projects around the world have failed because they didn’t adequately address fundamental social and ecological issues. Project leaders often didn’t ask communities what kinds of trees they wanted, planted species in places where they didn’t belong, and did little to help the saplings survive. “Tree planting is often viewed as the simple act of digging a hole,” forest scientists Pedro Brancalion of the University of São Paulo, Piracicaba, and Karen Holl of the University of California, Santa Cruz, noted last year in a review of agroforestry projects in the Journal of Applied Ecology. “But this short-term, naïve view has resulted in large quantities of money being spent on … efforts that have failed almost entirely.”
It’s a problem that Joda knows well. “I have traveled the breadth of Africa and seen it everywhere,” he says. “Trees are planted, but they are not taken care of and so they never grow.” The question now, he and others say, is whether Great Green Wall projects fueled by the fresh burst of cash will heed those hard-learned lessons.
New research published by Robert Loeb, a professor in biology and forestry at Penn State DuBois, outlines his efforts to bring the experience of rural forests to those who live in cities, with an eye toward what Loeb calls “environmental justice.” The article appears in the April issue of the publication Urban Forestry and Urban Greening.
Loeb’s article details new research discoveries about urban forests that veer from his typical concentrations. For decades he has studied forests in locations like New York City and Nashville, stewarding forest regeneration by examining the impact that wildlife and humans alike have on the forest and finding ways to curb this impact. This has led to work in a new urban-forest management protocol, “SAFE” — Soils, Aliens, Fire, Exclosure — with the goal of increasing natural regeneration through soil treatments, alien species treatments, fire surveillance, and fencing to eliminate problematic browsers such as deer.
Loeb took a turn toward research in soils when in 2014 he began to study tree regeneration in an urban forest in Philadelphia known as “The Good Woods,” part of the larger Haddington Woods in Cobbs Creek Park.
“The Good Woods is exceptional in having a mature canopy, a normal layer of leaf litter and organic matter, a large number of native tree seedlings, and less herbivory than typically expected,” said Loeb. “During 2015, an exclosure fence for deer was placed around the Good Woods and an act of arson caused a ground fire in approximately half of the forest.”
What sets the Good Woods apart from other similarly situated urban forests is that many native species seedlings and saplings grow naturally below the canopy created by larger trees. Loeb’s goal is to determine why this happened at this particular site, to hopefully replicate the natural tree regeneration in other cities.
Loeb recalled, “Growing up in the Bronx, I was accustomed to seeing urban forests with only tall trees. One summer I was awarded a scholarship from the Student Conservation Association to conduct research in Vermont. What struck me the most was that the forests there had seedlings that are lacking in urban areas. I’ve been trying throughout my career to sort out this lack of natural regeneration so that people in urban settings can enjoy the beauty of rural forests when we visit urban forests.”
The most trusted theory Loeb has on the difference in soil composition impacting the natural regrowth of new trees is one that he believes is rock-solid, so to speak.
“If you have more rocks, you have less soil. So, naturally you have a smaller population of trees,” he said. “I found many of the urban parks to have a great number of stones and even boulders in the soil. One particular area of the Good Woods is almost free of stones, and the soil there supports a greater growth of young trees.”
These findings could go a long way in helping Loeb to recommend soil studies and remediation in other urban forests. “Soils are a critical issue and need to be treated,” he said. “When I was young, horticulturalists taught me that if you spend $100 to plant a tree, you spend $10 on the tree and $90 on the soil. That is a formula that has not always been in use recently, but a historical perspective that maybe we need to revisit now.”
By Nell Greenfieldboyce
An ancient, well-preserved tree that was alive the last time the Earth’s magnetic poles flipped has helped scientists pin down more precise timing of that event, which occurred about 42,000 years ago.
This new information has led them to link the flipping of the poles to key moments in the prehistoric record, like the sudden appearance of cave art and the mysterious extinction of large mammals and the Neanderthals. They argue that the weakening of the Earth’s magnetic field would have briefly transformed the world by altering its climate and allowing far more ultraviolet light to pour in.
Their provocative analysis, in the journal Science, is sure to get researchers talking. Until now, scientists have mostly assumed that magnetic field reversals didn’t matter much for life on Earth — although some geologists have noted that die-offs of large mammals seemed to occur in periods when the Earth’s magnetic field was weak.
The Earth is a giant magnet because its core is solid iron, and swirling around it is an ocean of molten metal. This churning creates a huge magnetic field, one that wraps around the planet and protects it from charged cosmic rays coming in from outer space.
Sometimes, for reasons scientists do not fully understand, the magnetic field becomes unstable and its north and south poles can flip. The last major reversal, though it was short-lived, happened around 42,000 years ago.
Giant kauri trees can live for thousands of years and can end up well preserved in bogs. “The trees themselves are quite unique,” says Cooper. “They’re a time capsule in a way that you don’t really get anywhere else in the world.”
Inside trees that lived during the last magnetic flip, the researchers and their colleagues looked for a form of carbon created when cosmic rays hit the upper atmosphere. More of these rays come in when the magnetic field is weak, so levels of this carbon go up.
The trees, with their calendar-like set of rings, took in this kind of carbon and laid it down as wood. That let the researchers see exactly when levels rose and peaked and then fell again. One tree in particular had a 1,700-year record that spanned the period of the greatest changes.
By creating a precise timeline, the research team was able to compare the magnetic field’s weakening to other well-established timelines in the archaeological and climate records.
By Helen Briggs
Tree planting is a brilliant solution to tackle climate change and protect biodiversity, but the wrong tree in the wrong place can do more harm than good, say experts at the Royal Botanic Gardens, Kew.
The rules include protecting existing forests first and involving locals.
Forests are essential to life on Earth.
They provide a home to three-quarters of the world’s plants and animals, soak up carbon dioxide, and provide food, fuels and medicines.
But they’re fast disappearing; an area about the size of Denmark of pristine tropical forest is lost every year.
“Planting the right trees in the right place must be a top priority for all nations as we face a crucial decade for ensuring the future of our planet,” said Dr Paul Smith, a researcher on the study and secretary general of conservation charity, Botanic Gardens Conservation International, in Kew…
The 10 golden rules are:
Protect existing forests first
Keeping forests in their original state is always preferable; undamaged old forests soak up carbon better and are more resilient to fire, storm and droughts. “Whenever there’s a choice, we stress that halting deforestation and protecting remaining forests must be a priority,” said Prof Alexandre Antonelli, director of science at RGB Kew.
Put local people at the heart of tree-planting projects
Studies show that getting local communities on board is key to the success of tree-planting projects. It is often local people who have most to gain from looking after the forest in the future.
Maximise biodiversity recovery to meet multiple goals
Reforestation should be about several goals, including guarding against climate change, improving conservation and providing economic and cultural benefits.
Select the right area for reforestation
Plant trees in areas that were historically forested but have become degraded, rather than using other natural habitats such as grasslands or wetlands.
Use natural forest regrowth wherever possible
Letting trees grow back naturally can be cheaper and more efficient than planting trees.
Select the right tree species that can maximise biodiversity
Where tree planting is needed, picking the right trees is crucial. Scientists advise a mixture of tree species naturally found in the local area, including some rare species and trees of economic importance, but avoiding trees that might become invasive.
Make sure the trees are resilient to adapt to a changing climate
Use tree seeds that are suitable for the local climate and how that might change in the future.
Plan how to source seeds or trees, working with local people.
Learn by doing
Combine scientific knowledge with local knowledge. Ideally, small-scale trials should take place before planting large numbers of trees.
Make it pay
The sustainability of tree re-planting rests on a source of income for all stakeholders, including the poorest.
By Janet McConnaughey
When European settlers came to North America, fire-dependent savannas anchored by lofty pines with footlong needles covered much of what became the southern United States.
Yet by the 1990s, logging and clear-cutting for farms and development had all but eliminated longleaf pines and the grasslands beneath where hundreds of plant and animal species flourished.
Now, thanks to a pair of modern-day Johnny Appleseeds, landowners, government agencies and nonprofits are working to bring back pines named for the long needles prized by Native Americans for weaving baskets. The trees’ natural range spans the coastal plain, nine states from eastern Texas to southeast Virginia and extending into northern and central Florida.
Longleaf pines now cover as much as 7,300 square miles — and more than one-quarter of that has been planted since 2010.
“I like to say we rescued longleaf from the dustbin. I don’t think we had any idea how successful we’d be,” said Rhett Johnson, who founded The Longleaf Alliance in 1995 with another Auburn University forestry professor.
That’s not to say that the tall, straight and widely spaced pines will ever gain anything near their once vast extent. But their reach is, after centuries, expanding rather than contracting.
Scientists estimate that longleaf savannas once covered up to 143,750 square miles, an area bigger than Germany. By the 1990s, less than 3 percent remained in scattered patches. Most are in areas too wet or dry to farm.
Fire suppression played a critical role on the longleaf’s decline. Fires clear and fertilize ground that longleaf seeds must touch to sprout. Properly timed, they also spark seedlings’ first growth spurt. And, crucially for the entire ecosystem, they kill shrubs and hardwood trees that would otherwise block the sun from seedlings, grasses and wildflowers.
“The diversity of the longleaf pine system is below our knees,” sad Keith Coursey, silviculturist for about 70 percent of the 529,000-acre DeSoto National Forest in south Mississippi.
Of the 1,600 plant species found only in the Southeast, nearly 900 are only in longleaf forests, including species that trap bugs as well as fire-adapted grasses and wildflowers.
By Amy Androff
Could looking through trees be the view to a greener future? Trees replacing the clear pane glass in your windows is not a work of science fiction. It’s happening now.
Forest Products Laboratory (FPL) researcher Junyong Zhu in co-collaboration with colleagues from the University of Maryland and University of Colorado, have developed a transparent wood material that may be the window of tomorrow. Researchers found that transparent wood has the potential to outperform glass currently used in construction in nearly every way.
Their findings were published in the Journal of Advanced Functional Materials in their paper, “A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows.”
While glass is the most common material used in window construction it comes with a costly economic and ecological price.
Heat easily transfers through glass, especially single pane, and amounts to higher energy bills when it escapes during cold weather and pours in when it’s warm. Glass production in construction also comes with a heavy carbon footprint. Manufacturing emissions are approximately 25,000 metric tons per year.
Now, transparent wood is emerging as one of the most promising materials of the future.
Transparent wood is created when wood from the fast-growing, low-density balsa tree is treated to a room temperature, oxidizing bath that bleaches it of nearly all visibility. The wood is then penetrated with a synthetic polymer called polyvinyl alcohol (PVA), creating a product that is virtually transparent.
By Eric Hamilton
Deforestation dropped by 18 percent in two years in African countries where organizations subscribed to receive warnings from a new service using satellites to detect decreases in forest cover in the tropics.
The carbon emissions avoided by reducing deforestation were worth between $149 million and $696 million, based on the ability of lower emissions to reduce the detrimental economic consequences of climate change.
Those findings come from new research into the effect of GLAD, the Global Land Analysis and Discovery system, available on the free and interactive interface Global Forest Watch. Launched in 2016, GLAD provides frequent, high-resolution alerts when it detects a drop in forest cover. Governments and others interested in halting deforestation can subscribe to the alerts on Global Forest Watch and then intervene to limit forest loss.
By Amanda Peacher
In a region of Austria known as the wood quarter, a logger used a chainsaw to slice through the base of a 100-foot tall spruce tree on a recent foggy morning.
Herbert Schmid, a forester, watched from a distance as the big spruce dropped to the forest floor. Schmid handpicked that particular tree to be cut today. He manages this forest according to “close-to-nature” practices, or Pro Silva standards.
It’s an ancient technique of astute observation, low-intervention forestry that allows trees to grow and age before harvest. Forestry experts say it’s a valuable model as European forests face climate change and potentially more fires.