Importance of functional traits and regional species pool in predicting long-distance dispersal in savanna ecosystems
Long-distance dispersal (LDD) of plants is difficult to measure but disproportionately important for various ecological and evolutionary processes. Dispersal of seeds of gallery-forest trees in savanna provides an opportunity for the study of colonisation processes and species coexistence driven by LDD. Investigations were carried out on 91 isolated trees along four gallery forests sampled in the Biosphere Reserve of Pendjari, Benin. The abundance of adult trees within nearest gallery forest was combined with functional traits (species maximum height, seed weight, morphological adaptation for dispersal by wind, water, birds and mammals) to explain the floristic composition of forest seedlings and saplings under isolated trees and in savanna. Stepwise negative binomial regression was used to identify the most significant variables explaining abundance of seedlings and saplings beneath isolated trees and in savanna and then derive colonisation from seedlings and persistence from saplings. The maximum height of species and seed weight explained the highest proportion of variance in species colonisation. Morphological dispersal syndromes by wind and birds had poor explanatory importance. Species rare in gallery forest had higher potential to colonise new environments through LDD whilst abundant species had higher persistence abilities. Contrary to the predictions of the seedling-size effect, small-seeded species dominated the sapling stage. The findings revealed the strong dependence of LDD and subsequent colonisation and persistence processes on species traits specialised for a variety of dispersal vectors. They also suggest that LDD towards isolated trees established far away from gallery forest can be difficult.
KeywordsCoexistence Colonisation Dispersal strategy types Functional traits Local communities Regional species
Investigations were funded by LOEWE—Biodiversity and Climate Research Centre (BiK-F). A. F. Azihou was supported by ‘Programme d’Appui à l’Enseignement Supérieur (PAES)’ of the West African Economic and Monetary Union (UEMOA) through Grant No. 11484/2011/DDS/DESFP/PAES. We thank François Djatto and Henri Noundja for assistance in the field. The manuscript has been greatly improved with thoughtful reviews by Moses Adedire, Aristide Adomou, Achille Assogbadjo, Nestor Sokpon, Adjima Thiombiano and two anonymous reviewers.
- Akoegninou A, Van Der Burg WJ, Van Der Maesen LJG, Adjakidje V, Essou JP, Sinsin B, Yedomonhan H (2006) Flore analytique du Bénin. Wageningen UniversityGoogle Scholar
- Baddeley A, Turner R (2005) Spatstat: an R package for analyzing spatial point patterns. J Stat Softw 12:1–42Google Scholar
- Connell JH (1971) On the role of natural enemies in preventing competitive exclusion in some marine animals and rain forest trees. In: Den Boer PJ, Gradwell G (eds) Dynamics of populations. PUDOC, Wageningen, pp 298–312Google Scholar
- Nakazawa N (2013) fmsb: Functions for medical statistics book with some demographic data. R package version 0.3.8Google Scholar
- PAG2 (2005) Plan d’aménagement participatif et de gestion 2004–2013. Parc National de la Pendjari, BéninGoogle Scholar
- R Development Core Team (2013) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Ripley B, Venables B, Hornik K, Gebhardt A, Fith D (2013) Package MASS: support functions and datasets for Venables and Ripley’s MASS. R package version 7.3-26Google Scholar
- Royal Botanic Gardens Kew (2008) Seed Information Database (SID). Version 7.1. http://data.kew.org/sid/. Accessed 19 May 2012
- Sokpon N, Affoukou M, Amahowe I, Gandji L, Gnonlonfin L, Sossou B (2008) Dynamique spatio - temporelle des formations végétales du Complexe Parc National de la Pendjari, zones cynégétiques de la Pendjari et de l’Atacora. Laboratoire d’études et de recherches forestières, FA/UP/République du BéninGoogle Scholar
- Tsoar A, Shohami D, Nathan R (2011) A movement ecology approach to study seed dispersal and plant invasion: an overview and application of seed dispersal by fruit bats. In: Richardson DM (ed) Fifty years of invasion ecology: The legacy of Charles Elton. Wiley, Oxford, pp 101–119Google Scholar
- Wenny DG (2001) Advantages of seed dispersal: a re-evaluation of directed dispersal. Evol Ecol Res 3:51–74Google Scholar