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Repeated Summer Drought and Re-watering during the First Growing Year of Oak (Quercus petraea) Delay Autumn Senescence and Bud Burst in the Following Spring.

Vander Mijnsbrugge K, Turcsán A, Maes J, Duchêne N, Meeus S, Steppe K, Steenackers M - Front Plant Sci (2016)

Bottom Line: Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other.Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants.In both phenological models significant differences among the three provenances were detected independent from the treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Forest Genetic Resources, Research Institute for Nature and Forest Geraardsbergen, Belgium.

ABSTRACT
Climate change predicts harsher summer droughts for mid-latitudes in Europe. To enhance our understanding of the putative impacts on forest regeneration, we studied the response of oak seedlings (Quercus petraea) to water deficit. Potted seedlings originating from three locally sourced provenances were subjected to two successive drought periods during the first growing season each followed by a plentiful re-watering. Here, we describe survival and phenological responses after the second drought treatment, applying general linear mixed modeling. From the 441 drought treated seedlings 189 subsisted with higher chances of survival among smaller plants and among single plants per pot compared to doubles. Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other. Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants. This delay can be interpreted as a compensation time in which plants recover before entering the subsequent developmental process of leaf senescence, although it renders seedlings more vulnerable to early autumn frosts because of the delayed hardening of the shoots. Onset of bud flush in the subsequent spring still showed a significant but small delay in the drought treated group, independent of the number of seedlings per pot, and can be considered as an after effect of the delayed senescence. In both phenological models significant differences among the three provenances were detected independent from the treatment. The only provenance that is believed to be local of origin, displayed the earliest leaf senescence and the latest flushing, suggesting an adaptation to the local maritime climate. This provenance also displayed the highest standard deviation of plant height, which can be interpreted as an adaptation to variable and unpredictable weather conditions, favoring smaller plants in drought-prone summers and higher plants in more normal growing seasons.

No MeSH data available.


Related in: MedlinePlus

Boxplot representing the height of the seedlings in the drought stressed group according to the provenance and the number of seedlings per pot. Number of plants in each box are in Table 2 (nsu of stressed group).
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Figure 8: Boxplot representing the height of the seedlings in the drought stressed group according to the provenance and the number of seedlings per pot. Number of plants in each box are in Table 2 (nsu of stressed group).

Mentions: Survival of seedlings after severe water deficit appeared independent of the provenance. Still, a higher number of plants of KLA and BOR had died off compared to VOE (Table 2), because the model accounted for the height of the plants with smaller plants having a higher chance of survival. BOR was characterized by a higher mean height of plants and KLA did not show a higher mean height but a higher standard deviation compared to VOE, implying a relative larger number of high plants being more prone to starvation by drought (Figure 8). KLA is believed to be local of origin (Vander Mijnsbrugge et al., 2005). A cpDNA analysis revealed a uniform haplotype that fits in the reconstructed postglacial migration routes (Vander Mijnsbrugge et al., 2003). In addition, the mother trees are abandoned remnants of coppice wood in former heath land where no tradition existed among the relatively poor farmers of introducing foreign provenances. In a provenance trial, located in Belgium, KLA flushes later compared to several commercial provenances from western Germany (data not shown) indicating an adaptation to the less predictable weather (maritime climate) caused by oceanic influences with a smaller contrast between summer and winter and less predictable transitions. Other Belgian commercial provenances in this trial are typical planted forest stands, comparable to VOE and BOR, displaying an earlier flushing in spring, likely indicating a non-local origin of the mother trees. Similarly, in the here presented experiment leaves senesce earlier in KLA compared to VOE and BOR and, in addition, buds flush later, most probably indicating a shorter growing season as an adaptation to a more unpredictable temperate maritime climate for KLA and a non-local origin for VOE and BOR. The latter is likely as forest history in the northern part of Belgium is characterized by successive phases of deforestation and afforestation in this densely populated region (Vandekerkhove et al., 2011) resulting in a scattered and fragmented landscape, and in mostly relatively small oak forests of which a vast majority has a plantation origin, largely with an unknown origin of the planting stock. German origins of planting stock may have been planted as war reparations after the two world wars. The result stresses the importance of local provenances such as KLA not only because of the local adaptation to current climate as expressed by the phenological responses, but also because of putative larger variability in quantitative traits, as is the case for height growth in KLA. The latter probably also indicates for the planted stand VOE a stronger kinship and lesser diversity among the original planting stock (it may have been sourced on a limited amount of mother trees). As BOR was less sampled (only three mother trees) it is more difficult to make assumptions in this respect. The small variability in the quantitative trait height in the putative non-local provenance VOE can be related to the findings of Vranckx et al. (2014b). Based on a molecular genetic analysis (SSR), a stronger relatedness among the pedigrees of typical planted oak stands in the northern part of Belgium compared to the kinship among the mother trees was shown, which was attributed to forest fragmentation, which negatively influences genetic diversity (Vranckx et al., 2012), and is possibly strengthened by the plantation history of the mother trees (Vranckx et al., 2014a).


Repeated Summer Drought and Re-watering during the First Growing Year of Oak (Quercus petraea) Delay Autumn Senescence and Bud Burst in the Following Spring.

Vander Mijnsbrugge K, Turcsán A, Maes J, Duchêne N, Meeus S, Steppe K, Steenackers M - Front Plant Sci (2016)

Boxplot representing the height of the seedlings in the drought stressed group according to the provenance and the number of seedlings per pot. Number of plants in each box are in Table 2 (nsu of stressed group).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814502&req=5

Figure 8: Boxplot representing the height of the seedlings in the drought stressed group according to the provenance and the number of seedlings per pot. Number of plants in each box are in Table 2 (nsu of stressed group).
Mentions: Survival of seedlings after severe water deficit appeared independent of the provenance. Still, a higher number of plants of KLA and BOR had died off compared to VOE (Table 2), because the model accounted for the height of the plants with smaller plants having a higher chance of survival. BOR was characterized by a higher mean height of plants and KLA did not show a higher mean height but a higher standard deviation compared to VOE, implying a relative larger number of high plants being more prone to starvation by drought (Figure 8). KLA is believed to be local of origin (Vander Mijnsbrugge et al., 2005). A cpDNA analysis revealed a uniform haplotype that fits in the reconstructed postglacial migration routes (Vander Mijnsbrugge et al., 2003). In addition, the mother trees are abandoned remnants of coppice wood in former heath land where no tradition existed among the relatively poor farmers of introducing foreign provenances. In a provenance trial, located in Belgium, KLA flushes later compared to several commercial provenances from western Germany (data not shown) indicating an adaptation to the less predictable weather (maritime climate) caused by oceanic influences with a smaller contrast between summer and winter and less predictable transitions. Other Belgian commercial provenances in this trial are typical planted forest stands, comparable to VOE and BOR, displaying an earlier flushing in spring, likely indicating a non-local origin of the mother trees. Similarly, in the here presented experiment leaves senesce earlier in KLA compared to VOE and BOR and, in addition, buds flush later, most probably indicating a shorter growing season as an adaptation to a more unpredictable temperate maritime climate for KLA and a non-local origin for VOE and BOR. The latter is likely as forest history in the northern part of Belgium is characterized by successive phases of deforestation and afforestation in this densely populated region (Vandekerkhove et al., 2011) resulting in a scattered and fragmented landscape, and in mostly relatively small oak forests of which a vast majority has a plantation origin, largely with an unknown origin of the planting stock. German origins of planting stock may have been planted as war reparations after the two world wars. The result stresses the importance of local provenances such as KLA not only because of the local adaptation to current climate as expressed by the phenological responses, but also because of putative larger variability in quantitative traits, as is the case for height growth in KLA. The latter probably also indicates for the planted stand VOE a stronger kinship and lesser diversity among the original planting stock (it may have been sourced on a limited amount of mother trees). As BOR was less sampled (only three mother trees) it is more difficult to make assumptions in this respect. The small variability in the quantitative trait height in the putative non-local provenance VOE can be related to the findings of Vranckx et al. (2014b). Based on a molecular genetic analysis (SSR), a stronger relatedness among the pedigrees of typical planted oak stands in the northern part of Belgium compared to the kinship among the mother trees was shown, which was attributed to forest fragmentation, which negatively influences genetic diversity (Vranckx et al., 2012), and is possibly strengthened by the plantation history of the mother trees (Vranckx et al., 2014a).

Bottom Line: Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other.Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants.In both phenological models significant differences among the three provenances were detected independent from the treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Forest Genetic Resources, Research Institute for Nature and Forest Geraardsbergen, Belgium.

ABSTRACT
Climate change predicts harsher summer droughts for mid-latitudes in Europe. To enhance our understanding of the putative impacts on forest regeneration, we studied the response of oak seedlings (Quercus petraea) to water deficit. Potted seedlings originating from three locally sourced provenances were subjected to two successive drought periods during the first growing season each followed by a plentiful re-watering. Here, we describe survival and phenological responses after the second drought treatment, applying general linear mixed modeling. From the 441 drought treated seedlings 189 subsisted with higher chances of survival among smaller plants and among single plants per pot compared to doubles. Remarkably, survival was independent of the provenance, although relatively more plants had died off in two provenances compared to the third one with mean plant height being higher in one provenance and standard deviation of plant height being higher in the other. Timing of leaf senescence was clearly delayed after the severe drought treatment followed by re-watering, with two seedlings per pot showing a lesser retardation compared to single plants. This delay can be interpreted as a compensation time in which plants recover before entering the subsequent developmental process of leaf senescence, although it renders seedlings more vulnerable to early autumn frosts because of the delayed hardening of the shoots. Onset of bud flush in the subsequent spring still showed a significant but small delay in the drought treated group, independent of the number of seedlings per pot, and can be considered as an after effect of the delayed senescence. In both phenological models significant differences among the three provenances were detected independent from the treatment. The only provenance that is believed to be local of origin, displayed the earliest leaf senescence and the latest flushing, suggesting an adaptation to the local maritime climate. This provenance also displayed the highest standard deviation of plant height, which can be interpreted as an adaptation to variable and unpredictable weather conditions, favoring smaller plants in drought-prone summers and higher plants in more normal growing seasons.

No MeSH data available.


Related in: MedlinePlus