Dataset Information

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing.

ABSTRACT: Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral shoots of half of the investigated 5-year old Abies alba saplings were clipped to simulate browsing. At harvest, different fine-root classes were separated, and starch as an important storage compartment was analysed for concentrations. The phenology had a strong effect on the allocation of the 13C-label from shoots to roots. In spring, shoots did not supply the fine-roots with high amounts of the 13C-label, because the fine-roots contained less than 1% of the applied 13C. In summer and autumn, however, shoots allocated relatively high amounts of the 13C-label to the fine roots. The incorporation of the 13C-label as structural C or as starch into the roots is strongly dependent on the root type and the root diameter. In newly formed fine roots, 3-5% of the applied 13C was incorporated, whereas 1-3% in the ?0.5 mm root class and 1-1.5% in the >0.5-1.0 mm root class were recorded. Highest 13C-enrichment in the starch was recorded in the newly formed fine roots in autumn. The clipping treatment had a significant positive effect on the amount of allocated 13C-label to the fine roots after the spring labelling, with high relative 13C-contents observed in the ?0.5 mm and the >0.5-1.0 mm fine-root classes of clipped trees. No effects of the clipping were observed after summer and autumn labelling in the 13C-allocation patterns. Overall, our data imply that the season of C assimilation and, thus, the phenology of trees is the main determinant of the C allocation from shoots to roots and is clearly more important than browsing.

SUBMITTER: Endrulat T

PROVIDER: S-EPMC4849635 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Publications

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing.

Endrulat Tina T Buchmann Nina N Brunner Ivano I

PloS one 20160428 4

Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral shoots of half of the investigated 5-year old Abies alba saplings were clipped to simulate browsing. At ...[more]

PMID: 27123860

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Project description:The density of wild ungulates has increased in the last century, and browsing has become a major driver of forest succession in the northern hemisphere. In addition, tree species are expected to respond differently to future climate conditions, especially an increased frequency of late frost events. The aim of this study was to analyze the influence of intraspecific genetic variation on the recovery of two tree species to frost and browsing. An experiment with saplings from 90 Abies alba and 72 Picea abies seed sources was conducted. Five-year-old saplings were clipped at three intensities before budburst in spring. Growth (height, diameter, leader shoot length, and biomass) and quality (e.g. stem form, multistemming, reaction type) were assessed before and 1-2 years after clipping or 3-4 years after natural frost events, and provenance differences were related to environmental differences at the seed source. For Abies, frost and clipping resulted in reduced height growth in the first year after the stress and reduced height for two (clipping) to four (frost) vegetation periods. Sapling biomass, diameter increment, and quality decreased after heavy clipping. For Picea, which grew twice as fast as Abies, such effects were only found after frost damage. Population differences were significant for both species for all investigated growth traits and for Picea also for some quality variables. The "reaction type" after browsing (e.g. new shoot, existing twig bending upward) seems to be species specific and independent of seed source. In contrast, the time lag between clipping and formation of a clear new leader shoot increased for Abieswith lower temperatures at the seed source. Lowland populations with warmer climates grew faster, and for Picea also qualitatively better, and recovered faster from leader shoot loss (Abies) or reacted at the uppermost meristem (Picea). Thus, the investigated stressors increased the existing differences among populations.

Project description:Drought is one of the most important selection pressures for forest trees in the context of climate change. Yet, the different evolutionary mechanisms, and their environmental drivers, by which certain populations become more drought tolerant than others is still little understood. We studied adaptation to drought in 16 silver fir (Abies alba Mill.) populations from the French Mediterranean Alps by combining observations on seedlings from a greenhouse experiment (N = 8,199) and on adult tress in situ (N = 315). In the greenhouse, we followed half-sib families for four growing seasons for growth and phenology traits, and tested their water stress response in a "drought until death" experiment. Adult trees in the field were assessed for δ 13C, a proxy for water use efficiency, and genotyped at 357 SNP loci. SNP data was used to generate a null expectation for seedling trait divergence between populations in order to detect the signature of selection, and 31 environmental variables were used to identify the selective environment. We found that seedlings originating from populations with low soil water capacity grew more slowly, attained a smaller stature, and resisted water stress for a longer period of time in the greenhouse. Additionally, adult trees of these populations exhibited a higher water use efficiency as evidenced by their δ 13C. These results suggest a correlated evolution of the growth-drought tolerance trait complex. Population divergence in bud break phenology was adaptive only in the second growing season, and evolved independently from the growth-drought tolerance trait complex. Adaptive divergence in bud break phenology was principally driven by the inter- and intra-annual variation in temperature at the geographic origin of the population. Our results illustrate the different evolutionary strategies used by populations to cope with drought stress at the range limits across a highly heterogeneous landscape, and can be used to inform assisted migration programs.

Dataset Information

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing.

Publications

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing.

Similar Datasets

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