Solutions Summit | May 2022

Michael D. Pulliam


Researchers in Boston, MA, found that trees and soils on the edges of forests and in large city parks may capture more carbon than we thought.

Trees and the soils they grow in are vital parts of the global temperature balance. Trees ‘inhale’ carbon dioxide gas and separate the carbon to store in their trunks (turning gas into mass!). The trees then ‘exhale’ the oxygen byproduct, which is great news for creatures that breathe oxygen. This feature of holding carbon in trees and plants is known as a terrestrial carbon sink. “We’re not feeling the full effects of climate change because of the terrestrial [carbon] sink,” says Professor Lucy Hutyra, a biogeochemist and ecologist at Boston University.

But what happens to this process when large forests are fragmented by development? “We think about forests as big landscapes, but really they are chopped up into all these little segments because of the human world,” says Hutyra. What would otherwise be a large coverage area with a long-running forest edge becomes many small areas with many small edges. Historically, it has been assumed the trees and soils along a forest edge capture and release carbon at similar rates as forest interiors. But Hutyra and researchers in her PhD lab at Boston University have published two papers describing their findings to the contrary.

In a pair of studies, Hutyra and her teams observed that trees on the edges grow faster than their counterparts within the forest, and that soil in urban areas can hold more carbon than expected.

Their work is one of the most detailed reports of temperate forest edges to date. Examining data from more than 48,000 forest plots around the Northeastern US, Hutyra and her team found that edge trees grow nearly twice as fast as trees just 100 feet deeper into the forest. “This is likely because the trees on the edge don’t have competition with interior forest, so they get more light,” says Luca Morreale, lead author of the report. The more a tree grows, the more carbon it is holding.

Hutyra and another team conducted a related study focused on soils. “Soils contain wild amounts of bacteria, fungi, roots, and microorganisms,” says Sarah Garvey, PhD candidate and lead author of the soils paper. “And just the way we breathe out CO2 when working and being active, they respire CO2, as well.” Visiting eight field sites every two weeks for 18 months, the researchers’ measurements showed that in rural areas with lower foot traffic, organic matter at a forest edge decomposed more quickly, releasing carbon back into the system at higher rates than forest interiors. Urban forest soils were hotter and drier overall and released less carbon than expected, potentially acting as longer-term carbon sinks.

Their results give us more reasons to love urban green spaces, adding carbon sinks onto the list alongside species habitats, recreation uses, and mental health benefits.

Sources: Good News Network


Two British designers used invasive species to replace some of the ingredients in concrete, resulting in a strong, sustainable building material with colors so stunning they pleased global luxury brands.

Brigitte Kock and Irene Roca Moracia are the design duo behind this beautiful bio-concrete. They combined their concern for the high price of invasive species removal and its wasteful disposal rules with concern for the emissions-heavy process of making concrete. Of particular interest were Japanese knotweed and American signal crayfish: corrosive knotweed has no predators in the UK and must be removed by specialists, while crayfish undercut riverbanks and speed up erosion and sedimentation. Once collected, these species (among others) are sealed up and stored or shipped away.

But the duo found that incinerating the knotweed produced ashes which could replace the sand in concrete, and pulverized crayfish shells could replace the gravel component. This removes two highly carbon-intensive steps that are common in making concrete. Moracia remarked, “We want to showcase the absurdity of the classification and disposal rules here in the UK that do not allow anything to be done with those species after they are treated and sealed in bags, while you can easily order those byproducts online and import them from China for example.”

And then there are the colors. Good News Network described a variety of rich, gorgeous tones that put to shame the dull grey of typical concrete: Jade green, dark burgundy, marbled colors, natural stone…. “We have played with the percentages and ratios to obtain really strong results,” Moracia explained.

The task was commissioned by LVMH, a conglomerate of luxury brands including Dior and Louis Vuitton. The commission was part of a graduate program in collaboration with the London-based art and design college Central Saint Martins. The program aims to innovate sustainable construction materials for use in luxury stores, and “to respond to the environmental emergency and mobilize emerging talents, through creative education.”

Sources: Good News Network,