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A number of traits have been attributed important roles in tolerance of shade by plants. Some explanations emphasize traits enhancing net carbon gain; others emphasize energy conservation traits such as storage of non-structural carbohydrates (NSC). To date, cross-species studies have provided mixed support for the role of NSC storage in low-light survival. We examined NSC status, survival, biomass, and growth of large seedlings of two evergreen species of differing shade tolerance ( Nothofagus nitida and N. dombeyi) grown in deep shade and 50% light for two growing seasons. We expected to find higher NSC concentration in the more shade-tolerant N. nitida and since allocation to storage involves sacrificing growth, higher growth rate in the shade-intolerant N. dombeyi. NSC concentration of both species was >twofold higher in 50% light than in deep shade, and in roots and stems did not differ significantly between species in either environment. NSC contents per plant were also similar between dead and living plants in deep shade. N. dombeyi outgrew N. nitida in 50% light, while this pattern was reversed in deep shade. Survival in deep shade was not correlated with NSC concentration. Leaf mass fraction was similar between species in 50% light, but lower in N. dombeyi in deep shade. Results provide little evidence of a link between carbohydrate storage and low-light survival in Nothofagus species, and support the view that understorey survival is primarily a function of net carbon gain. Patterns of variation in NSC concentration of the temperate species we studied are likely dominated by more important influences than adaptation to shade, such as limitation of growth or adaptation to cold stress. [ABSTRACT FROM AUTHOR]

1. Carbohydrate storage has been attributed an important role in the ability to tolerate shade, yet empirical support for this idea has been patchy. We asked if carbohydrate-storage patterns of seedling evergreens in low light are correlated with variation in shade tolerance, and how these patterns change with seedling size. 2. We measured biomass distribution and total non-structural carbohydrate (NSC) concentrations of leaves, stems and roots of two seedling size classes of six evergreens growing in a temperate rainforest understorey. Light requirements of the six species were quantified by calculating the 10th percentile of the distribution of established seedlings in relation to canopy openness. 3. NSC averaged 14% of the dry mass of small seedlings (40–60 mm tall), and 22% of that of large seedlings (400–600 mm tall). This difference was entirely due to variation in starch reserves, which on average accounted for 60% of NSC in small seedlings and 84% in large seedlings. 4. NSC concentrations of leaves and roots (but not stems) of large seedlings were negatively correlated with species’ shade tolerance, but no such pattern was found in small seedlings. Leaf NSC on an area basis was not related to species’ shade tolerance in either size class. 5. Partitioning of the NSC pool between leaves, stems and roots of small seedlings was closely related to variation in shade tolerance. Small seedlings of shade-tolerant species had a relatively low proportion of their NSC pool in leaves and a high proportion in roots. This is likely to ensure the retention of the greater part of the NSC pool even in the event of extensive defoliation, and the availability of reserves to replace lost leaves. In contrast, the large leaf-mass fraction of large seedlings of shade-tolerant species (46–47% of biomass) meant that these plants had a large proportion of their NSC pool in foliage. 6. Results suggest that, in Chilean rainforest evergreens, any adaptive relationship of carbohydrate storage with shade tolerance may be confined to young seedlings, involving interspecific variation in the partitioning of reserves between leaves and other organs, rather than especially high NSC concentrations in shade-tolerant species. [ABSTRACT FROM AUTHOR]

The article presents author's commentary on biobanks. Topics discussed include rising need for high-quality biological samples in biomedical research, individual academic institutions to support researchers, and the field of personalized medicine. Also being discussed is the evolution of biodiversity and the health status of individual members of a species.