It is not water, but the light is
the main factor determining the growth opportunities of hundreds of tropical
forest trees species. The variation in physiological characteristics between
species can explain how these species occupy different ecological niches,
thereby contributing to the biodiversity of tropical forests. This is what
describes a paper published in PNAS by researchers at Wageningen University and
the University of Utrecht.
Tropical forests are composed of
hundreds of species in one hectare, but the source of creation of this
biodiversity is still unknown. The study by Frank Sterck, Lourens Poorter and
Lars Markesteijn (Wageningen UR) and Feike Schieving (Utrecht University) shows
that the Bolivian tree species can coexist because they occupy the same niche.
The species studied all react differently to changes in light and water
availability, with all the different physiological characteristics.
Biodiversity is an essential element for many species.
In this study, many physiological
traits such as leaf area, wood mass, photosynthetic capacity, and leaf
resistance to water were measured on trees tropical forests of Bolivia. The
researchers also developed a physiological model calculates the rate at which
species can grow under different combinations of input water and light. The
simulations show that some species are specific to certain niches, because they
have photosynthetic capacity and production of different leaves.
The researchers conclude that
light, even in relatively dry tropical forests, is the ideal engine for the
specialization of species in different niches, and therefore more important
than water for the coexistence of different species factor.
This is one of the first studies
in which models of plant physiology are used to determine the characteristics
of growth and survival of different species to explain the richness of plant
biodiversity in tropical forests. In the future, these models will be used to
help determine the distribution of plant species along a climatic gradient.
