Interspecific and intraspecific variation in tree seedling survival: effects of allocation to roots versus carbohydrate reserves

Abstract

We examined interspecific and intraspecific variation in tree seedling survival as a function of allocation to carbohydrate reserves and structural root biomass. We predicted that allocation to carbohydrate reserves would vary as a function of the phenology of shoot growth, because of a hypothesized tradeoff between aboveground growth and carbohydrate storage. Intraspecific variation in levels of carbohydrate reserves was induced through experimental defoliation of naturally occurring, 2-year-old seedlings of four northeastern tree species -Acer rubrum, A. saccharum, Quercus rubra, and Prunus serotina- with shoot growth strategies that ranged from highly determinate to indeterminate. Allocation to root structural biomass varied among species and as a function of light, but did not respond to the defoliation treatments. Allocation to carbohydrate reserves varied among species, and the two species with the most determinate shoot growth patterns had the highest total mass of carbohydrate reserves, but not the highest concentrations. Both the total mass and concentrations of carbohydrate reserves were significantly reduced by defoliation. Seedling survival during the year following the defoliation treatments did not vary among species, but did vary dramatically in response to defoliation. In general, there was an approximately linear relationship between carbohydrate reserves and subsequent survival, but no clear relationship between allocation to root structural biomass and subsequent survival. Because of the disproportionate amounts of reserves stored in roots, we would have erroneously concluded that allocation to roots was significantly and positively related to seedling survival if we had failed to distinguish between reserves and structural biomass in roots.

Root architecture and allocation patterns of eight native tropical species with different successional status used in open-grown mixed plantations in Panama

“…These results agree with those published by other authors (Reich et al 1998;Huante et al 1992;Paz 2003), although this study was carried out on a broader plant size gradient and on roots larger than 2 mm. The thicker root system of non-pioneer species supports the hypothesis that allocation to storage or defence is favoured in these species at the expense of soil exploration (Kobe 1997;Canham et al 1999). Investment in soil exploration would in contrast be needed by pioneer species to compensate higher aboveground development (i.e.…”

Climate warming alters nitrogen dynamics and total non-structural carbohydrate accumulations of perennial herbs of distinctive functional groups during the plant senescence in autumn in an alpine meadow of the Tibetan Plateau, China

“…As a consequence, the root biomass was underestimated in this study. Root samples were ground using a mechanical mill, after which, approximately 0.1 g ground aliquots were analyzed for total non-structural carbohydrate (TNC) through the conversion of sugars and starches to glucose equivalents followed by colorimetric analysis (Canham et al, 1999). …”

Global patterns of insect herbivory in gap and understorey environments, and their implications for woody plant carbon storage

“…2). The fact that preferential carbon allocation to storage in late-successional species is more characteristic of tropical than of temperate forests (Kitajima 1994, Canham et al 1999, Lusk and Piper 2007, Myers and Kitajima 2007, Poorter and Kitajima 2007, Piper 2015 is therefore unlikely to be explained by differential herbivore responses to light availability gradients in tropical versus temperate forests. Although the low opportunity cost of allocation to storage in shaded understories has been emphasized (Kobe 1997), it is unclear why similar patterns have not consistently been observed in shade-tolerant species of temperate forests (Canham et al 1999, Lusk andPiper 2007).…”

“…Although some studies have found evidence linking seedling shade tolerance to carbon allocation to storage (Canham et al 1999, Kitajima 1994, Poorter and Kitajima 2007, several others did not (Canham et al 1999, Lusk and Piper 2007, Piper 2015, Piper et al 2009, 2017. One possible explanation for the discrepancy is that, in some regions, the levels of understorey herbivory are insufficient to select for herbivory tolerance.…”