From a young age we are taught about the importance of trees; how they help us breathe and how they clean the air. Later on, we learn about habitat and pollination, shade cover and the sociological impacts of greenery. But, it is not often discussed what trees themselves can teach us. Two recent articles from The New York Times and The Washington Post provide ample facts and additional perspectives on the greater understanding of trees and their role in climate, how humans can affect that role and what an understanding of said role can do for us in the near future.
Both the fields of dendroclimatology and paleoclimatology, to be discussed later, provide critical knowledge to our understanding of the planet. According to a recent article in The New York Times, certain trees yield abundant evidence of past climatic patterns and offer insight on possible future outcomes of climate change. For example, the Great Basin bristlecone pine trees of the American west, some of the oldest trees on Earth, are giving forest researchers clues to the endurance of the species as they defy thousands of years of climate change manifestations.
Despite myriad climate struggles in the arid climates of California, Utah and Nevada, such as severe drought, fierce wildfires and bark beetles, the bristlecone pines are steadily thriving. One bristlecone pine located in the Methuselah Grove in California, (its exact location is kept secret by the U.S. Forest Service for its protection), is believed to be 4,855 years old, the oldest on Earth. Scientists believe this longevity is due to the trees’ extremely slow growth, about one inch in diameter every 100 years, which has allowed the tree to develop a thick bark and added protection from the elements and wildfires. This increases the ability to persist in such a dry climate, which holds fewer competitors overall. Examining the outer grooves in the dense wood indicates the trees’ health, past endurance and age.
Additionally, cross-sections of a tree’s trunk will reveal rings that are used in conjunction with carbon dating to determine the age and health of an individual tree. Paramount in research of tree rings is historical relevance and comparison, as explored in the field of dendroclimatology. The primary differences among tree rings are coloration and thickness; dendroclimatologists then use the knowledge from the rings, as well as current knowledge of individual species and climate, to define endemic climate anomalies and other patterns that can provide context for how species may react to upcoming weather and climatic patterns.
Depending on differing climates, ring boundaries and wood density can reconstruct depictions of historic climatic changes. A combined study of rings has shown that almost all of the planet, despite global climate variance, has been consistently warming since the Industrial Revolution. This shows definite results from human-driven climate change and exemplifies the importance of tree ring data in natural archives.
Paleoclimatology, the study of undocumented climate history, will help us garner a greater understanding of the true extent of human interference with Earth’s natural changes in climate cycles. Additionally, this reconstruction of geological patterns and systems allows for further advancement of potentially beneficial ecosystem management innovations. Several academic groups have proposed ideas for invasive species integration into sustainable forestry projects; this includes building ecological diversity through controlled burning and mindful planting of new species. Advancements in biotechnology for the detection of invasive species are being researched, as are genetically modified trees as part of Integrated Pest Management (IPM) techniques. By studying the outcomes of IPM within forest ecology, scientists can learn more about potential outcomes of these widespread IPM techniques in other fields as we endeavor to battle climate change.
As discussed in the article from The Washington Post, researchers based at SUNY College of Environmental Science and Forestry in Syracuse, New York have found an enzyme that could, through gene manipulation, save and bring back the “functionally extinct” American chestnut tree. Since the early 20th century, the American chestnut tree has been battling extinction via interference from an exotic fungus, whose arrival, as well as the arrival of many other arboreal diseases threatening the lives of native trees, was linked to global trade. The enzyme that researchers detected exists naturally in other plants, but the introduction of this enzyme into the chestnut tree and surrounding ecosystem requires significant approval (federal, agricultural and other). The transgenic (genetically modified) American chestnut tree is known as “Darling 58.”
Notably, Darling 58 could pose a turning point in genetically modified tree species as the outcomes relate to aggressive invasive beetles; this is due to their specific interactions with the pests. If the FDA approves this alteration, this type of enzyme manipulation could open the door to a new era of IPM techniques and arboreal gene adaptations against invasive beetles as well, not just fungal diseases. In a diseased American chestnut tree, chestnut blight manifests as the fungus Cryphonectria parasitica, which releases oxalic acid, killing cells and allowing for the fungus to eat away at dead tree tissue. Researchers have located the encoding gene oxalate oxidase (OxO) in other crops (barley, for one), and engineered pollen to contain OxO. Specifically, oxalate oxidase breaks down the oxalic acid, keeping the fungus from eating tree tissue. This makes OxO safer in the long term because it still allows for a minor infection from the fungus, but stops the spread to the whole tree. The genetically engineered pollen will flower chestnuts that carry the OxO blight resistant DNA, allowing the next generation of chestnut trees to be resilient against Cryphonectria parasitica. Since the manipulation is only contained in one chromosome of the engineered pollen’s DNA, about half of the flowered chestnuts contain the blight resistance. This building up of immunity is what will protect the tree in the long term, ideally, much like the incredibly dense wood and thick bark of the bristlecone pine.
Tests on gene inheritance longevity have shown that blight resistance remains at about the same levels through generations. In this scenario, trees are strong actors in the ecological community and study of ecosystem management. While Darling 58 is evolving into a success story in the field, actions regarding invasive species and pests have been slower on the pick up.
Invasive beetles continue to be vexations for scientists, as damage prevention via early detection and rapid response is most important, but preemptive preventative action remains futile. Many proposed tactics are largely contested due to the potential development of super-pests that are resistant to IPM or other aggressive chemical attacks. This review of articles and ecological fields has prompted further questions. For example, the bristlecone pine’s strength is largely understood to come from the thick bark and dense wood of the tree. However, if there is one, would forestry scientists and researchers be able to identify a part of the bristlecone pine’s DNA that aids this strength? If so, is it possible that in the event of Darling 58’s approval, the DNA code that bolsters the bristlecone pine’s longevity gets woven into the DNA of other struggling tree species through cross-pollination (like has been done with Darling 58)? Though, would it be practical to have such strong and slow-growing trees as the band-aid fix to struggling forestry? Additionally, if this occurs, what would the further effects of these long-living tree species be on their surrounding environments?
As long as trees can teach us about history, we can learn from them about the future. These multifaceted topics are culminating in groundbreaking research all over the world, however quietly. A more widespread understanding of these climate mitigation tactics and our environmental history should be a goal as we continue into this era of intense climate change debates and calls for imminent action.