Forest Products Industry

A lot of attention has been paid to how climate change can drive biodiversity loss. Now, MIT researchers have shown the reverse is also true: Reductions in biodiversity can jeopardize one of Earth’s most powerful levers for mitigating climate change. Source: Timberbiz In a paper published in PNAS, the researchers showed that following deforestation, naturally regrowing tropical forests, with healthy populations of seed-dispersing animals, can absorb up to four times more carbon than similar forests with fewer seed-dispersing animals. Because tropical forests are currently Earth’s largest land-based carbon sink, the findings improve our understanding of a potent tool to fight climate change. “The results underscore the importance of animals in maintaining healthy, carbon-rich tropical forests,” said Evan Fricke, a research scientist in the MIT Department of Civil and Environmental Engineering and the lead author of the new study. “When seed-dispersing animals decline, we risk weakening the climate-mitigating power of tropical forests.” Mr Fricke’s co-authors on the paper include César Terrer, the Tianfu Career Development Associate Professor at MIT; Charles Harvey, an MIT professor of civil and environmental engineering; and Susan Cook-Patton of The Nature Conservancy. The study combines a wide array of data on animal biodiversity, movement, and seed dispersal across thousands of animal species, along with carbon accumulation data from thousands of tropical forest sites. The researchers say the results are the clearest evidence yet that seed-dispersing animals play an important role in forests’ ability to absorb carbon, and that the findings underscore the need to address biodiversity loss and climate change as connected parts of a delicate ecosystem rather as separate problems in isolation. “It’s been clear that climate change threatens biodiversity, and now this study shows how biodiversity losses can exacerbate climate change,” Mr Fricke said. “Understanding that two-way street helps us understand the connections between these challenges, and how we can address them. These are challenges we need to tackle in tandem, and the contribution of animals to tropical forest carbon shows that there are win-wins possible when supporting biodiversity and fighting climate change at the same time.” The next time you see a video of a monkey or bird enjoying a piece of fruit, consider that the animals are actually playing an important role in their ecosystems. Research has shown that by digesting the seeds and defecating somewhere else, animals can help with the germination, growth, and long-term survival of the plant. Mr Fricke has been studying animals that disperse seeds for nearly 15 years. His previous research has shown that without animal seed dispersal, trees have lower survival rates and a harder time keeping up with environmental changes. “We’re now thinking more about the roles that animals might play in affecting the climate through seed dispersal,” Mr Fricke said. “We know that in tropical forests, where more than three-quarters of trees rely on animals for seed dispersal, the decline of seed dispersal could affect not just the biodiversity of forests, but how they bounce back from deforestation. We also know that all around the world, animal populations are declining.” Regrowing forests is an often-cited way to mitigate the effects of climate change, but the influence of biodiversity on forests’ ability to absorb carbon has not been fully quantified, especially at larger scales. For their study, the researchers combined data from thousands of separate studies and used new tools for quantifying disparate but interconnected ecological processes. After analysing data from more than 17,000 vegetation plots, the researchers decided to focus on tropical regions, looking at data on where seed-dispersing animals live, how many seeds each animal disperses, and how they affect germination. The researchers then incorporated data showing how human activity impacts different seed-dispersing animals’ presence and movement. They found, for example, that animals move less when they consume seeds in areas with a bigger human footprint. Combining all that data, the researchers created an index of seed-dispersal disruption that revealed a link between human activities and declines in animal seed dispersal. They then analysed the relationship between that index and records of carbon accumulation in naturally regrowing tropical forests over time, controlling for factors like drought conditions, the prevalence of fires, and the presence of grazing livestock. “It was a big task to bring data from thousands of field studies together into a map of the disruption of seed dispersal,” Mr Fricke said. “But it lets us go beyond just asking what animals are there to actually quantifying the ecological roles those animals are playing and understanding how human pressures affect them.” The researchers acknowledged that the quality of animal biodiversity data could be improved and introduces uncertainty into their findings. They also note that other processes, such as pollination, seed predation, and competition influence seed dispersal and can constrain forest regrowth. Still, the findings were in line with recent estimates. “What’s particularly new about this study is we’re actually getting the numbers around these effects,” Mr Fricke said. “Finding that seed dispersal disruption explains a fourfold difference in carbon absorption across the thousands of tropical regrowth sites included in the study points to seed dispersers as a major lever on tropical forest carbon.” In forests identified as potential regrowth sites, the researchers found seed-dispersal declines were linked to reductions in carbon absorption each year averaging 1.8 metric tons per hectare, equal to a reduction in regrowth of 57%. The researchers say the results show natural regrowth projects will be more impactful in landscapes where seed-dispersing animals have been less disrupted, including areas that were recently deforested, are near high-integrity forests, or have higher tree cover. “In the discussion around planting trees versus allowing trees to regrow naturally, regrowth is basically free, whereas planting trees costs money, and it also leads to less diverse forests,” Terrer said. “With these results, now we can understand where natural regrowth can happen effectively because there are animals planting the seeds for free, and we also can identify areas where, because animals are affected, natural regrowth is not going to happen, and therefore planting trees actively is necessary.” […]

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Have you ever examined timber floorboards and pondered why they look the way they do? Perhaps you admired the super-fine grain, a stunning red hue or a swirling knot, and wondered how it came to be? Source: The Conversation Or perhaps you don’t know what tree species your floorboards are made from, and how to best look after them? Finely polished floorboards reveal detail about the timber that can be much harder to detect in unpolished boards or other sawn timbers. “Reading” the knots, stubs and other characteristics of floorboards can reveal what type of tree produced it and how it grew. It can also reveal fascinating details about the lives of the trees they once were. A variety of tree species are used to make timber floors. Hardwood species include the pale cream of Tasmanian oak, the honeyed hues of spotted gum and the deep red of jarrah. Other times, softwood such as pine or spruce is used. Such species are often fast-growing and prized for their availability and affordability. Hardwoods are, by definition, flowering trees, while softwoods are from cone-bearing trees. Paradoxically, not all softwoods are soft or hardwoods hard. The balsa tree, for example, is a fast-growing hardwood tree renowned for its soft wood. It’s not always easy to tell if a floor is hardwood or softwood, but there are discernible differences in their appearance. The real differences between softwood and hardwood lie in the anatomy and structure of the “xylem tissues” that make up the wood. These tissues transported water and nutrients from the roots to the rest of the plant when the tree was alive. The arrangement of xylem tissue in the tree largely determines the “grain” in your floorboards. The grain is the appearance of wood fibres in the timber. The grain can be straight, wavy or spiralled. In floorboards with straight grains, a tree’s growth history may be clear. As a tree trunk grows in diameter, it typically produces a layer of bark on the outside and a lighter layer of xylem tissue on the inside. When a tree is cut horizontally, the growth appears as rings. In a tree cut lengthwise (which happens when floorboards are milled) the growth appears as long lines in the timber. If the lines in floorboards are very close together, this indicates the tree grew slowly. Wider lines suggest the tree grew rapidly. Vessels in a tree’s xylem transport water from the roots to the rest of the plant. Hardwood tree species tend to have large vessels. This gives hardwood floorboards a coarser-grained and less uniform appearance. In contrast, softwood species such as conifers have smaller, dispersed vessels and produce more fine-grained, smoother timber. Knots in floorboards occur when a branch dies or is cut, then tissue grows over the stub. The bigger the missing branch, the more substantial the knot. Knots in floorboards can reveal much about the source tree. Pine, for example, often features multiple small knots originating from a common point. This reflects the growth pattern of young plantation pines, where several branches grow out from the trunk at the same height from the ground. Often, the distance between knots tells us how quickly the tree grew. The greater the distance between the knots, the faster the tree grew in height. The presence of a tree’s “defence chemicals”, known as polyphenols, can be seen clearly in some floorboards. Polyphenols protect plants against stressors such as pathogens, drought and UV radiation. The chemicals contribute to the red hue in some floorboards. Because polyphenols have a preservative effect, they can also make timber more durable. Dark reddish or brown timbers containing a high concentration of polyphenols include mahogany, merbau, red gum, ironbark and conifers such as cedar and cypress. In cases where a tree is burnt by fire, or attacked by insects or fungus, it produces a lot of polyphenols at the site of the damage. In these cases, the presence of polyphenols in floorboards can be very obvious – sometimes appearing as a section that is dark brown verging on black. It’s widely known that living trees store carbon, and that this helps limit climate change. It’s less well known that timber floorboards also store carbon. And as long as that timber is preserved – and not destroyed by fire, decay or wood rot – that carbon will stay there. If floorboards have to be removed, try to make sure the timber is reused or repurposed into other products. And if you are installing a new polished timber floor, or already have one, there are steps you can take to make it last for a long time. Softwood boards will benefit from a hard surface coating, especially in high-use areas. Reducing the floor’s exposure to bright sunlight can preserve the colour of the floorboards and prolong the life of the coating and the timber itself. Large knots in floorboards can twist and start to protrude from the surface. To ensure the floor remains even and safe, and to prevent the board from splitting, secure the knot to a floor joist with a nail or glue. And take the time to understand the lessons embedded in your floorboards. They have much to teach us about biology and history, if we take the time to read them.

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