Penn State DuBois professor has the ‘dirt’ on sustainable urban forests

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.”

Source: Penn State DuBois professor has the ‘dirt’ on sustainable urban forests – Penn State University, 2021-02-11

Hidden giants in forest soils

Only a fraction of the microbes residing in, on and around soils have been identified through efforts to understand their contributions to global nutrient cycles. Soils are also home to countless viruses that can infect microbes, impacting their ability to regulate these global cycles. In Nature Communications, giant virus genomes have been discovered for the first time in a forest soil ecosystem by researchers from the DOE Joint Genome Institute and the University of Massachusetts-Amherst.

Characterizing the diversity of microbial cells in a handful of soil is so complex it was considered impossible. To date, only a small fraction of the microbes residing in, on and around soils have been identified as part of efforts to understand their contributions to the global carbon cycle, and to other nutrient cycles. Soils are also home to countless viruses that can infect microbes, impacting their ability to regulate these global cycles.

Reported November 19, 2018, in Nature Communications, giant virus genomes have been discovered for the first time in a forest soil ecosystem by researchers from the U.S. Department of Energy (DOE) Joint Genome Institute (JGI), a DOE Office of Science User Facility, and the University of Massachusetts-Amherst (UMass Amherst). As the name implies, giant viruses are characterized by disproportionately large genomes and virions that house the viruses’ genetic material. They have been frequently found within protists and algae, and thus they are believed to have a significant impact on their hosts’ population dynamics and the planet’s biogeochemical cycles.

Source: Hidden giants in forest soils – EurekAlert, 2018-11-19

Part of the Answer to Climate Change May Be America’s Trees and Dirt, Scientists Say

By Brad Plumer
A new study found that the United States could store enough carbon in natural landscapes to offset all the cars and trucks on the road.

When people think of potential solutions to global warming, they tend to visualize technologies like solar panels or electric cars. A new study published on Wednesday, however, found that better management of forests, grasslands and soils in the United States could offset as much as 21 percent of the country’s annual greenhouse gas emissions.

At the high end of the projections, that would be roughly equivalent to taking every single car and truck in the country off the road.

The paper, published in the journal Science Advances, identified a number of promising strategies, like replanting trees on degraded lands, changing logging practices to better protect existing forests and sequestering more carbon in farmland soils through new agricultural techniques.

“We’re not saying these strategies are a substitute for getting to zero-carbon energy; we still need to do that too,” said Joseph E. Fargione, a scientist at the Nature Conservancy and lead author of the study. “But we think that natural climate solutions generally get overlooked. And we found a lot of opportunities here to help mitigate climate change.”

Source: Part of the Answer to Climate Change May Be America’s Trees and Dirt, Scientists Say – New York Times, 2018-11-14

Soil fungi help tree seedlings survive, influence forest diversity

A new paper published Jan. 13 in Science reveals that the relationship between soil fungi and tree seedlings is more complicated than previously known. The paper was co-written by Ylva Lekberg, an assistant professor of soil community ecology at the University of Montana.

Lekberg and her collaborators studied 55 species and 550 populations of North American trees. Scientists have long known that plants and soil biota can regulate one another, but the new findings highlight the complexity of the feedback loop.

“Fungi differ in their ability to protect tree seedlings from pathogens, and this has implications for seedling recruitment and therefore forest community patterns,” Lekberg said.

Most plant roots are colonized by mycorrhizal fungi, but tree species associate with different fungal groups. The researchers showed that ectomycorrhizal fungi that form a thick sheet around root tips are better able to protect trees from pathogens than arbuscular mycorrhizal fungi.

Thus, while ectomycorrhizal tree seedlings actually prefer growing next to parent trees, arbuscular mycorrhizal tree seedlings can only establish outside the control of parents’ enemies. This can have consequences for how temperate forests are structured and their overall diversity.

Source: Soil fungi help tree seedlings survive, influence forest diversity — ScienceDaily, 2017-01-13