A relaxing stroll through the woods is increasingly becoming an intense cardiovascular workout, as a new report from researchers at Aarhaus University in Denmark indicates that that the world’s forests are slowly being relegated to steep, mountainous slopes. According to study author Brody Sandel, the increasingly efficient removal of trees from flat areas around the world raises concerns about the biodiversity of the world’s forests in the future. “The remaining forests on slopes are typically divided into smaller areas that are not continuous,” Sandel said. “For example, fragmentation reduces the availability of interior forest habitat that is preferred by many bird species. There are also a number of large predators, such as big cats like the tiger, which require extensive areas of continuous forest to be able to get enough food or avoid human persecution.” According to the study, which was published Tuesday in the journal Nature Communications, developed countries are especially efficient at razing forests in flat areas of arable land. The study researchers identified a clear connection between a thriving economy, a more organized society and a more efficient means of restricting forests to steep slopes, due to their lower utility and value. The team arrived at their findings through the analysis of images taken from satellites that monitor global forest ecosystems with a fine level of detail. High-resolution global satellite data revealed the distribution of global tree cover from 2000 to 2005 and its connection to terrain, climate, human activity, and a range of other factors. Study researchers found that the relegation of forests to steep slopes has also recently accelerated in less well-developed countries, many of which have begun to clear forests in pursuit of greater agricultural capacity and urban development. In remote areas of the Amazon, Siberia and the Congo, there are still large, uninterrupted stretches of virgin forests, the Danish scientists said. However, as populations grow and human impacts increase, the researchers expect development to increasingly affect even these relatively desolate regions. Some developed societies around the world have reforestation programs and other forests are naturally regrowing as people move from hillsides to the highly populated regions below. Both trends strengthen the movement towards future forests becoming pushed up and onto slopes, the Danish scientists said. In addition to concerns over biodiversity, small and fragmented forests are more likely to be affected by wind impact, have intense sunlight on the forest floor, and be more disturbed. The result would be a hotter and drier microclimate, potentially promoting species that do not require a stable, dense forest and upsetting the balance of an ecosystem. “On the other hand, species in steep mountainous areas can better track their preferred climate as it becomes warmer,” said co-author Jens-Christian Svenning, a professor in the Department of Bioscience at Aarhus University. “Hence, considering future climate change, it’s fortunate that forests will especially occur on steep terrain in the future,” he added. “It’s thus a blessing in disguise that the general loss of forests has less effect on slopes.”