Self-organization in raised bog patterning: the origin of microtope zonation and mesotope diversity

1 Raised bogs of the boreal and temperate zone typically show surface patterning on two distinct organizational levels. A conspicuous pattern of alternating dry strings and wet flarks aligned perpendicular to the slope occurs in combination with other microtopes, resulting in a mesotope pattern. 2 Patterning on both these levels can be explained by a simple, spatially explicit model that assumes predominantly lateral water flow through an acrotelm that is draped over a dome-shaped catotelm. The model distinguishes two types of surface elements: hummocks with low transmissivity growing under dry conditions and hollows with high transmissivity growing under wet conditions. 3 Hummocks dam up water and stimulate the development of hollows upslope, whereas hollows effectively drain upslope areas, stimulating the development of hummocks. If the dome is steep and the recharge high enough, this leads to the development of a string-flark microtope. 4 Four distinct types of microtopes are distinguished: (i) areas entirely covered by hummocks, (ii) randomly arranged hummocks and hollows, (iii) string-flark striping patterns and (iv) areas entirely covered by hollows. 5 Different combinations of sharply delineated microtopes occur with different parameter settings, allowing for the classification of four types of raised bog mesotopes. In addition to such qualitative differences, the extent and composition of the microtopes vary with parameter settings, reflecting the variety observed in natural systems. 6 Our simple simulation model shows how small-scale, local processes can create a variety of large and complex landscape patterns. These patterns can be used to describe raised bogs in terms of biological entities of a higher organizational order (ecosystem biodiversity), typically recognizable in often species-poor peatland ecosystems.