Reaching similar goals by different means - Differences in life-history strategies of clonal and non-clonal plants
Abstract
Clonality is a largely underexplored plant life-history trait with possibly profound effects on plant demography. Clonal growth constitutes an alternative reproductive pathway, which should provide clonal species with an advantage over non-clonal ones under disturbance regimes unfavourable to regeneration from seeds.
We investigated how clonal and non-clonal species differ in their life histories (other than clonality) and how this relates to disturbance regimes where the studied species occur. Further, we focused on the contribution of clonality to fluctuations in the populations of species and the importance of clonality for the life cycle of a species in relation to its other life-history characteristics.
We achieved this through phylogenetically informed analyses of the matrix population models available from the COMPADRE database coupled with information on species clonality from the CLO-PLA database. The phylogenetic principal component analysis revealed that plant life-history characteristics could be aligned along two gradients.
The gradient of generation time and individual turnover in populations was more important and corresponded to the frequency of habitat disturbance. Clonal species on average had populations with lower overall rates of individual turnover and disturbance frequencies.
The second gradient was correlated with disturbance severity and plant ability to regenerate after the loss of biomass. The importance of clonal growth for the life cycle of a clonal species increased with more severe disturbance events.
The fluctuation of population growth rates depended on the life-history characteristics of a species but not on clonality. The net effect of clonal growth on the fluctuations of the populations of a species was positive.
In general, clonality seems to provide an important alternative for adjusting plant life history to the disturbance regime and other site conditions allowing a plant to circumvent its morphological or developmental constraints. Clonal growth turned out to be mainly a mechanism that enables population expansion under favourable conditions rather than a mechanism that buffers the effects of adverse conditions.