P1-8: The role of heterogeneity in spatial plant population dynamics

PhD student: Clara-Sophie van Waveren
Thesis Committee: Prof. Kerstin Wiegand, Dr. Katrin Meyer, Prof. Thomas Kneib

A recent field study (Getzin et al. 2008) demonstrated that spatial heterogeneity per se can be a determinant of plant population dynamics and pattern formation. Ecological processes, i.e. individual-individual interactions and individual-environment interactions result in spatial patterns at different critical scales. The model assumption of a homogeneous landscape is often needed (Schlather 2001) to distinguish these interactions. Important growth patterns may be masked by spatial heterogeneity in soil properties (wet drainage sites, dry shallow soils), edaphic gaps (rock outcrops and scree) and topography (relief, aspect) which may cause a patchy (clustered) distribution of trees. In addition, niche separation may be affected by micro habitat heterogeneity such as variability in forest floor micro relief.
At larger scales, the macro relief may alter the distribution of trees. Such processes are unidentifiable under the assumption of homogeneity and may lead to wrong conclusions. In other words, results from homogeneous study areas may not hold in heterogeneous study areas because plant demography differs under heterogeneous conditions.
To better understand the role of heterogeneity, we propose to investigate critical spatial scales for competition, growth, and mortality for a natural mixed beech forest in the Hainich National Park in a fully mapped stand of over 15.000 trees.
The aim is to develop appropriate statistical methods to deal with spatial heterogeneity in (plant) ecology towards a better understanding of plant population dynamics without the makeshift of assuming homogeneity.

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