Significance of structural complexity
Against the background that future challenges due to climate change might result in a dramatically increased importance of the buffer or adaptive capacity of an ecosystem, the above said has important implications. If it is possible to measure structural complexity of an ecosystem, one might be able to provide a proxy for its adaptive capacity. For trees and forests, the quantification of the overall structural complexity in three-dimensional (3D) space is today possible based on terrestrial, mobile and airborne 3D laser scanning (Atkins et al. 2018b, Ehbrecht et al. 2017; 2021, Seidel 2018, Dorji et al. 2021, Stiers et al. 2020, Willim et al. 2020). Global approaches based on spaceborne laser scanning from the international space station (ISS) by means of NASA’s GEDI (global ecosystem dynamics investigation) also provide tools for an assessment of forest complexity and structure mapping (e.g. Schneider et al. 2020). With structure and complexity available, it is equally important to gain information on tree species identity. Here, large progress has also been made when it comes to species identification for example from infrared sensors (e.g. Pan et al. 2022). Silviculturists know ways to increase the complexity of managed forests (Peck et al. 2014), mimicking natural developments (e.g. Messier et al. 2013) or admixing additional tree species, resulting in forests that produce timber but that are almost as complex as primary forests at the same time (e.g. Stiers et al. 2020). Figure 1 provides a visual representation of the theoretical ideas present here.