Selbstdünnung

Selbstdünnung, a German term, translates to "self-thinning" or "self-pruning" in English. It refers to a phenomenon observed in dense plant populations where individuals begin to die off as competition for resources intensifies. This process is a natural consequence of population growth exceeding the carrying capacity of the environment.

As plants grow and their numbers increase within a confined space, they inevitably compete for essential resources such as sunlight, water, nutrients, and space. Plants that are less successful in this competition, often due to being smaller, shaded, or genetically less vigorous, will eventually succumb. Their death contributes to a reduction in overall population density.

The rate of self-thinning can vary depending on the plant species, environmental conditions, and the initial density of the population. It plays a crucial role in regulating population size and can influence the growth and development of the surviving individuals. The remaining plants often experience improved access to resources, leading to increased growth rates and larger sizes.

In ecological studies, self-thinning is often characterized by a predictable relationship between the average size of individuals and the population density, often described by the "-3/2 power law" or the " $-5/2$ power law." This law suggests that as the average biomass of an individual plant increases with the $-3/2$ power of density, the total biomass of the population remains constant. Understanding self-thinning is important for managing natural ecosystems, agricultural crops, and forestry plantations.