Variations in the success of plant species are due to two factors – reproduction success and development speed – according to the conclusions of ecologists working on biodemography. The precise appearance of a plant and where or in which climate it lives are far less important for its survival. A study of the characteristics of 418 plant species spread over diverse biotopes worldwide demonstrated this. The study, carried out by scientists from Radboud University and other institutes, will be published online by PNAS in the week of 21 December.
Plants and animals less different than expected
Reproduction success and development speed have long been known to be decisive factors in the survival of animals. Researchers are surprised that they are also very important for plants. “Plants are fundamentally different,” Radboud University plant ecologist Hans de Kroon reminds us. They are static. And, in contrast to animals, their shape is not fixed. Plants can produce many extra branches that bear extra flowers and, subsequently, fruit. They can expand their root system if more food is necessary. Cloning is possible. And if conditions are not ideal, they can reject pieces of their plant body to save energy in order to survive.”
Colleague Eelke Jongejans, an animal ecologist, also points out differences. “In animals the speed of their development is responsible for 80% of the variation in their life history; in plants that is ‘only’ 36%.”
Worldwide collection of plants
The plants in this study have been recorded in a new, public-access research database, COMPADRE, making it possible to compare the life histories of much larger groups of plant species and to discover general patterns.
“This conclusion may not surprise you and it would, in fact, be quite strange if the life histories were very different to observations made in the field. The size of the study enables us to demonstrate what applies everywhere, namely, that species differ foremost in the speed of their life cycles – from annuals to extremely long-living plants – and further, in how many offspring they have. More surprising is the fact that this variation shows remarkable overlap among plant groups that are not related to each other. Species with differing growth forms, such as herbaceous plants as opposed to shrubs, or species from highly contrasting environments – rainforest, deserts, flooded deltas – often have very comparable survival mechanisms in their ecosystems,” Hans de Kroon says. “This research shows that simple demographic characteristics can already tell us a great deal; we don’t always need information about the shape and thickness of the leaves, wood density, seed size and root structure.”
Modelling plant communities
The researchers’ colleagues included Pieter Zuidema (Wageningen University) and the main author, Roberto Salguero-Gómez from the Max Planck Institute for Demographic Research. This institute usually focuses on trends in human populations but its methodology turned out to be equally applicable to plants.
Jongejans and De Kroon regard this new approach as a way to start modelling plant communities. These generally applicable survival patterns should make it possible in the future to, for example, estimate whether non-indigenous species could become invasive.
Fast-slow continuum and reproductive strategies structure plant life history variation worldwide. Salguero-Gómez R , OR Jones, E Jongejans, SP Blomberg, D Hodgson, C Mbeau-Ache, PA Zuidema, H de Kroon & YM Buckley (2015). PNAS MS# 2015-06215, 21 december 2015.