|Title||Some trees grow faster than others: why?|
|Group||Forest Ecology and Forest Management Group|
|Supervisor(s)||Prof. Dr. P.A. (Pieter) Zuidema|
|Examiner(s)||Prof.Dr. F.J.J.M (Frans) Bongers|
|Description||Within populations of trees, there are substantial differences in the growth rates of equal-sized trees. Such growth differences between individuals can persist for several decades, and cause trees to strongly differ in age when they reach the size at which they become reproductive or are allowed to be harvested. For instance, some tropical cedar trees reach harvestable size (50 cm diameter) when they are 40 years old while others take almost four times as long. Such persistent growth differences have important implications for estimations of future timber stocks and the viability of populations of threatened tree species. The causes of persistent growth variation include differences in light level, crown size and soil conditions among trees. Tree-ring analyses can be used to show the degree of persistent growth variation among individuals, but tree rings do not provide information about the growing conditions of trees. A first evaluation of causes of persistent growth variation may be obtained by relating current light conditions and canopy position of trees to past growth rates obtained from tree-ring analyses. That is the goal of this thesis. You will use data from a pan-tropical tree-ring study in which the crown illumination index and canopy closure index of all 1300 individuals were obtained and for which tree-ring measurements already have been performed. You will use statistical analyses (mixed effect models) to relate light conditions to past growth rates for various periods of time, taking size-differences between trees into account.
Population and forest dynamics / Tree ring analyses and wood anatomy/ America's/ Africa /Asia/Tropical zone
|Requirements||FEM-30306 Forest Ecology and Forest Management; REG-31806 Ecological Methods I;|