Newswise — The managed secondary forests bore the brunt of the harsh impact from the dry summer of 2018 in Sweden, as revealed by a recent study conducted at Lund University.
In the future, Northern boreal forest ecosystems are anticipated to face increasingly frequent summer droughts. In Sweden, the majority of forests consist of managed commercial secondary forests, characterized by limited species diversity and structural variation. Conversely, only a small portion comprises primary forests that have encountered minimal direct human influence.
Up until now, the response of primary forests and managed secondary forests to drought has remained unknown. However, a recent study, published in the scientific journal Environmental Research Letters and led by a team of researchers from Lund, delved into the impact of the 2018 drought on these two distinct forest types.
Anders Ahlström, a researcher in physical geography at Lund University, explained that their study utilized a distinctive map of primary forests in Sweden to explore potential differences in the impact of the 2018 drought on these forests compared to neighboring secondary forests. The findings revealed that secondary forests in Sweden suffered more severe consequences from the drought than primary forests did.
During the study, the research team employed satellite images and a comprehensive map containing information on over 300 primary forests in Sweden. By scrutinizing a high-resolution vegetation index across both the primary forests and their adjacent buffer zones, which represented secondary forests with similar environmental conditions and drought exposure during the summer of 2018, the researchers gained valuable insights into the varying impact of the dry season on these distinct forest types.
“That primary forests were less affected by drought leads to a number of interesting follow-up questions about what causes this difference. It could be the trees’ generally greater age and size that perhaps leads to deeper roots and more structural diversity. Or it could be that there is more water in these ecosystems, perhaps because they haven’t been ditched. Right now though, we have no idea what makes primary forests more stable during drought,” says Julika Wolf, former physical geography researcher, now a consultant on cartography and spatial analysis.
Primary forests are a rarity in both Sweden and Europe, serving as valuable remnants of untouched natural habitats. They provide crucial insights into the unaltered state of nature and its functioning without significant direct human influence. Consequently, these forests play a pivotal role in comprehending the impact of environmental changes and human land use on ecosystems and their processes.
Anders Ahlström emphasized that the study effectively demonstrates how primary forests can be utilized in research. The findings reveal that, in this instance, primary forests exhibit greater stability during drought compared to secondary forests, which have undergone various alterations such as felling, planting, ground preparation, and ditching. This underscores the importance of preserving and studying these unique primary forest ecosystems to enhance our understanding of ecological resilience and sustainable land management practices.
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