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Ecosystem diversity

To determine the diversity of ecosystems, food webs were used. The topological network structure of aquatic and terrestrial ecosystems (49 of each) were analyzed to evaluate potential differences in the number of structures of each group. 

To determine the effect of species richness on food web structure variation, 128 Swedish and 48 North American lake food webs were also analyzed. 

To estimate the network structure of the food webs, 25 different topological network properties (e.g. proportion of top predators, mean trophic level of the speceis, link density) was calculated. These properties were then used as axes in a multidimensional coordinate system, in which each food web could be fitted. The euclidean distance between food webs could then be used as a measurment of their similiarity. The average distance between the food webs and their group centroid can then be seen as the group diversity.


Illustration of Euclidean distances to a spatial median in two dimensions. Each point is a food web in Group 1 (blue) or Group 2 (green) and the colored lines are the Euclidean distances from each food web to its group spatial median (SMG). The striped black lines are the Euclidean distances from all food webs to the combined spatial median of both groups (SMC). In this example there is larger diversity at the ecosystem level in Group 1 than in Group 2.

Responsible for this page: Agneta Johansson
Last updated: 06/01/16