High-integrity human intervention in ecosystems: Tracking self-organization modes
Fig 6
Emergence of oblique self-organized (SO) modes in afforestation projects.
(a) A region of size 30x30 [m] containing four stripes of planted trees along bunds, taken from aerial images of the northern Negev region (Coordinates: 31.295N, 34.815E) in 2010 and 2019. (b) Model results of a comparable system, consisting of four initial vegetation stripes that has been subjected to a precipitation downshift from P = 205 to P = 180 [mm/yr] at t = 0, and simulated to t = 200[yr] (see full details in Materials and methods section and S1 Appendix). Note that similarly to Fig 3, but with different values of P, at high precipitation (P = 205) both stripe and rhombic patterns are stable, but at low precipitation (P = 180) stripe patterns are no longer stable. Top row shows spatial images, while bottom row shows spectral densities obtained from spectral (FFT) analysis, which demonstrates the periodicity of vegetation along different directions. The empirical spectral density in 2010 (a) shows the dominance of a stripe SO mode (yellow dots on x axis), representing the original planted pattern, while that in 2019 shows, in addition, the development of oblique modes (light-blue dots off the x axis), which represent vegetation mortality to form a spot-like pattern. The model simulations in (b) show a similar trend. During the transient dynamics towards a rhombic pattern the emerging pair of oblique modes are not symmetric (compare with Fig 4) both in the empirical data and the model simulations. However, simulations to longer times (t = 200[yr]) indicate the eventual emergence of a symmetric pair of oblique modes.