Evolution of vegetation structure

Department of Mathematics and Mathematical Statistics, Umeå University, Umeå, Sweden

Magnus Lindh

Magnus Lindh

One of the most intriguing questions in biology is why there is such a high diversity of species. In a tropical rain forest, thousands of species of trees can coexist on only a few square kilometers of land as the result of a long process of evolutionary diversification.

The general aim of my project is to develop a better understanding of the ecological mechanisms and principles underlying diversification in tree architecture. Using simple eco-evolutionary models, we will first determine tree architectures that maximize the seed production of a solitary tree, so that there is no influence of other trees. Second, we will analyze monomorphic or polymorphic outcomes of architecture evolution of trees in stands, in which competition for light, the risk of wind breakage, and the pattern of grazing a tree experiences depend on other trees in its stand.

As a first approximation, trees will be assumed to have simple geometric shapes consisting of a spheroidal crown, whose top is attached to the tip of a conical trunk. Each tree will be characterized by three evolving traits: the trunk’s apex angle, the relation of crown width to crown height, and the amount of available energy invested into the crown relative to the trunk.

In a horizontally well mixed stand, the effects of wind, grazing, and light competition depend on the stand’s vertical biomass distribution, and thereby on the architectures of all trees in the stand, rendering selection on trees in stands frequency-dependent. We will consider stands of trees that occasionally are destroyed through fires and then re-established from similar stands through global random seed dispersal.

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Last edited: 24 March 2016

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