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- Piqueras, Jesús, 1961-, et al.
(författare)
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Demography and modelling of clonal fragments in the pseudoannual plant shape Trientalis europaea L
- 1998
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Ingår i: Plant Ecology. - 1385-0237 .- 1573-5052. ; 136:2, s. 213-227
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Tidskriftsartikel (refereegranskat)abstract
- The clonal growth pattern and demography of clonal fragments (aggregation of ramets derived from a common parent ramet) in the pseudoannual plant Trientalis europaea were studied in field conditions from 1991 to 1993. During this period the population of clonal fragments declined, with a half-life of 7.4 years. Number and size of the clonal progeny and stolon length were positively related to the size of the mother ramet. Survival rates of ramets and tubers increased with size. The rate of clonal growth was low: after three years, about 70% of the clonal fragments had only one ramet. This suggests that the pseudoannual growth habit in T. europaea is more important as mechanism of perennation than of ramet multiplication.Field data were used in a simulation model of architecture and population dynamics of clonal fragments. About 10% of the clonal fragments survived to the end of the simulation (15 years) and the mean survival was 4.7 years. The model predicted a positive correlation between persistence of the clonal fragment and number of ramets produced. Sensitivity analysis showed that the production of a daughter ramet of at least the same size as the parent ramet was the most important pathway for the survival and the number of ramets of the clonal fragment, whereas the production of secondary ramets had a very small effect. This confirms the interpretation of the pseudoannual life-cycle as a mechanism of ramet replacement in this species. Sensitivity analysis also revealed that changes in survival probabilities of the smallest ramets had the largest impact on clonal fragment dynamics. This reflects the important role of the smallest size class of ramets as a source of new vegetative propagules, maintaining a hierarchy in the size structure of the population.
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| 3. |
- Piqueras, Jesús, 1961-, et al.
(författare)
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Modelling the morphological response to nutrient availability in the clonal plant Trientalis europaea L
- 1999
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Ingår i: Plant Ecology. - 1385-0237 .- 1573-5052. ; 141:1-2, s. 117-127
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Tidskriftsartikel (refereegranskat)abstract
- The morphological responses to changes in environmental quality shown by many clonal plants have been interpreted as an expression of foraging behaviour, as they allow the ramets to become concentrated in more favourable microhabitats. The morphological response to increased nutrient availability in the pseudoannual plant Trientalis europaea was studied in a field experiment. The response was largely size-dependent and consistent with enhanced clonal growth. Fertilized ramets produced more tubers and a larger main tuber. In contrast, stolon length was not affected by the treatment. A spatially explicit simulation model calibrated with data from the field experiment examined the population dynamics of T. europaea ramets in a spatially hetereogeneous, temporally constant, environment. The model showed that T. europaea was effective at concentrating its ramets in favourable patches, but this process was strongly influenced by patch size. The analysis of this response at the clone level showed that ramet aggregation was mainly due to the enhanced performance of clones located initially in the favourable patches, or clones that located a favourable patch by chance. In these clones, the simultaneous increase of ramet size and survival accelerated the production of ramets. The temporal and spatial scale at which the aggregation of ramets in favourable patches was manifested suggests that the effectiveness of the morphological response in T. europaea is favoured by a high spatio-temporal predictability in the environment. Overall, the model emphasized the important role of population dynamics in understanding the nature of the foraging response.
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| 4. |
- Diekmann, M, et al.
(författare)
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Beech forest communities in the Nordic countries - a multivariate analysis
- 1999
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Ingår i: PLANT ECOLOGY. - : KLUWER ACADEMIC PUBL. - 1385-0237. ; 140:2, s. 203-220
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this study we present the first comprehensive multivariate analysis of beech (Fagus sylvatica) forest communities in the Nordic countries. The history of beech and beech forests in Scandinavia are described. In the north, the species is climatically re
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