Methods of species pool determination as predictors of survival in seeding and transplanting experiments

1. Community composition is limited by a species' ability to reach, establish and survive on a site. Establishment and survival are constrained by both abiotic conditions and biotic interactions that operate together on local scales. They decide which species from the pool will form the community. For this reason, it is very important to clearly define the species pool, against which the community com- position is compared.2. The effect of biotic and abiotic factors can be assessed experimentally, and the species pool by using estimation methods based on broad -scale observational data. We compared success of five species pool estimation methods in predicting establishment and survival in a seed/transplant addition experiment.3. In four different locations, we added resident and non-resident species to plots with and without competition and tested the ability of the species to thrive in both competition -free gaps (constrained mainly by abiotic conditions) and in intact vegetation (complete community filter). In these treatments, we studied the seedling recruitment and survival, and the establishment and survival of pregrown transplants. The ability of species pool assessment methods to predict species performance in individual treatments was compared. The comparison of results from individual treatments indicates the importance of individual components of the community filter.4. Species pool assessment methods, based on species co-occurrence patterns (Beals index, favourability and unconstrained ordination), were the best predictors of species performance in the intact vegetation, but were less successful in the competition -free environment. Methods based on co-occurrence patterns were the most effective for predicting seedling establishment, while seed germination alone and transplant survival were poorly predictable.5. The biotic filter was the principal factor defining our community composition, especially for the process of seedling establishment. The roles of biotic and abiotic filters are very difficult to distinguish without an experimental approach and the ratio of their importance changes during plant ontogenesis.

Automated summary

Community composition is determined by a species' ability to survive and establish in a particular site, which is influenced by both abiotic conditions and biotic interactions. It is crucial to accurately define the species pool for comparison with the community composition.