Landscape features shape forest growth and carbon storage patterns

Landscape Features Shape Forest Growth and Carbon Storage Patterns

Scientists at Alabama A&M University have discovered that differences in landform - such as slope, bench, or valley - play a major role in determining which tree species grow best and store the most carbon on different parts or the landscape in temperate forests. Their detailed study at the Paint Rock Forest dynamics plot, part of the ForestGEO network, mapped every single tree across 20 hectare (29,282 trees total), revealing interesting patterns about how different tree species respond to their surroundings. Compared to species biomass per hectare on other landforms, yellow-poplar biomass in the valleys is 54% greater, while the biomass of American beech is 37% more. In contrast, southern shagbark hickory biomass per hectare is nearly 4 times more on slopes than in the valleys. White ash and oak exhibit a similar but less pronounced trend. Sugar maple is the only tree species that grows equally well on all examined landforms at the site. While the forest stores about 211 tons of tree biomass per hectare on average, some parts of the plot have 25 times more than others, indicating the importance of local conditions and micro-topography and habitats.

These findings show how forests tree species occupy different niches and dominate different landforms, likely achieving greater growth and biomass than a mono-specific stand would. The way species partition the landscape—valley specialists versus slope specialists—is what allows the forest stand to achieve robust biomass everywhere. This discovery is important for sustainable forest management and studies on climate impact in forest ecosystems. By knowing which trees grow best in valleys, slopes, or ridges, foresters can choose to favor the best adapted species for a particular landform in the studied region. For climate scientists, the study shows that small-scale terrain variation is often associated with substantial variation in woody biomass and that tree species should be included as a variable in estimating carbon sequestration —ignoring them could lead to large errors in estimating forest carbon storage.

Published in Forest Ecosystems, this collaborative work involved scientists from Alabama A&M University, University of Vermont, and the Paint Rock Forest Research Center, with support from USDA and the National Science Foundation. "Our findings provide tangible tools for developing nuanced approaches to carbon accounting and forest ecosystem management in a changing environment," emphasized Dr. Lemke.

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