| 1. |
- Bylin, Anja, et al.
(författare)
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Influence of nitrogen fertilization on growth and loline alkaloid production of meadow fescue (Festuca pratensis) associated with the fungal symbiont Neotyphodium uncinatum.
- 2014
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2790 .- 1916-2804. ; 92, s. 370-376
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Tidskriftsartikel (refereegranskat)abstract
- In a field study during two growing seasons in northern Sweden, we assessed meadow fescue (Festuca pratensis Huds.) with and without Neotyphodium uncinatum to determine whether the endophyte affects plant performance regarding tiller and biomass production. In addition, we measured loline alkaloids produced in infected grasses. Approximately 1000 plants grew at two different levels of nitrogen fertilization: the normal amount applied in this region and one-half that amount. Increasing the amount of nitrogen increased the total number of tillers on the plants. Endophyte-infected plants produced more tillers per plant than plants without the endophyte; there was, however, no significant difference in proportion of reproductive tillers, winter survival, or total biomass production between endophyte-infected and noninfected plants. Infected plants produced loline alkaloids in different quantities without indication of being influenced by different nitrogen fertilization levels.
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| 2. |
- Johansson, Veronika A., et al.
(författare)
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Recruitment limitation, germination of dust seeds, and early development of underground seedlings in six Pyroleae species
- 2013
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2790 .- 1916-2804. ; 91:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- We investigated recruitment of six mixotrophic Pyroleae species in relation to soil and adult presence. Pyroleae have dust seeds containing minimal nutrient reserves, and subterranean seedlings are mycoheterotrophic needing fungal hosts for germination and development. Germination and seedling development were studied by retrieving seed bags that had been placed within plots with adults present and at unoccupied control plots. There are two main alternatives to what limits recruitment of plants, seed limitation or microsite limitation. Results suggested that a combination of microsite and seed limitation was important for all investigated species. Microsite availability was the main limiting factor for Chimaphila umbellata (L.) W. P. C. Barton, Orthilia secunda (L.) House, and Pyrola chlorantha Sw., whereas seed availability was the main limiting factor for Pyrola minor L. For Moneses uniflora L. A. Gray and Pyrola rotundifolia L., it was not clear whether microsite or seed limitation dominated. Growth of seedlings responded positively to adult presence (O. secunda and P. minor), whereas others were negatively affected (M. uniflora and P. chlorantha). Increased levels of soil nutrients (N and P) had a negative effect on seedling growth in C. umbellata and P. chlorantha. These results provide the first evidence of the importance of microsite and seed limitation for germination and development of seedlings of Pyroleae species.
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| 3. |
- King, Connor, et al.
(författare)
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Diatoms and other siliceous indicators track the ontogeny of a “bofedal” (Wetland) ecosystem in the peruvian andes
- 2021
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2790 .- 1916-2804. ; 99:8, s. 491-505
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Tidskriftsartikel (refereegranskat)abstract
- Recent warming in the Andes is affecting the region’s water resources including glaciers and lakes, which supply water to tens of millions of people downstream. High-elevation wetlands, known locally as “bofedales”, are an understudied Andean ecosystem despite their key role in carbon sequestration, maintenance of biodiversity, and regulation of water flow. Here, we analyze subfossil diatom assemblages and other siliceous bioindicators preserved in a peat core collected from a bofedal in Peru’s Cordillera Vilcanota. Basal radiocarbon ages show the bofedal likely formed during a wet period of the Little Ice Age (1520–1680 CE), as inferred from nearby ice core data. The subfossil diatom record is marked by several dynamic assemblage shifts documenting a hydrosere succession from an open-water system to mature peatland. The diatoms appear to be responding largely to changes in hydrology that occur within the natural development of the bofedal, but also to pH and possibly nutrient enrichment from grazing animals. The rapid peat accretion recorded post-1950 at this site is consistent with recent peat growth rates elsewhere in the Andes. Given the many threats to Peruvian bofedales including climate change, overgrazing, peat extraction, and mining, these baseline data will be critical to assessing future change in these important ecosystems.
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| 4. |
- Lankinen, Åsa, et al.
(författare)
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Geographic variation in floral traits is associated with environmental and genetic differences among populations of the mixed mating species Collinsia heterophylla (Plantaginaceae)
- 2017
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2804 .- 1916-2790. ; 95:2, s. 121-128
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Tidskriftsartikel (refereegranskat)abstract
- Relatively few studies have investigated how geography, environmental factors, and genetics affect floral trait variation. We used mixed-mating Collinsia heterophylla Buist to explore variation in a suite of floral traits related to mating system in populations representing four geographic regions of California, USA, and relate this variation to geography, climatic factors, and local site characteristics. We evaluated the environmental vs. genetic trait variability in the greenhouse. Stage of anther–stigma contact correlated positively with temperature, stage of stigma receptivity was negatively associated with vegetation cover, and flower size differed among populations without any clear relation to environmental factors. Greenhouse data indicated heritability for stage of anther– stigma contact, flower size, and time to flowering, and positive correlations between field and greenhouse for stage of stigma receptivity and flower size; however, stage of anther–stigma contact showed a high degree of environmental influence. Stage of anther–stigma contact covaried positively with stage of stigma receptivity and flower size across maternal families, indicating genetic correlations between traits. In conclusion, phenotypic floral variation within mixed-mating C. heterophylla is mostly determined by a genetic component. Geography, environment, and genetics affect traits differently, suggesting that ecological and evolutionary processes contribute to shaping variability in mating system-related traits.
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| 5. |
- Lessard-Therrien, Malie, et al.
(författare)
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Predicting flowering phenology in a subarctic plant community
- 2014
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2790 .- 1916-2804. ; 92:10, s. 749-756
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Tidskriftsartikel (refereegranskat)abstract
- Phenological studies are rarely reported from arctic and subarctic regions, but are essential to evaluate species' response to climate change in these rapidly warming ecosystems. Here, we present a phylogenetic analysis of flowering phenology across an elevational gradient in the Canadian subarctic. We found that the timing of first flower was best explained by a combination of snowmelt, elevation, and growing degree-days. We also show that early flowering species have demonstrated lower intraspecific variability in their response to climate cues in comparison with late flowering species, such that individual flowering times of early species are more closely tied to environmental predictors. Previous work has suggested that early flowering species are more variable in their phenology. However, these studies have mostly examined variation in phenology over time, whereas we examined variation in phenology over space. We suggest that both patterns can be explained by the tighter coupling between phenology and climate cues for early flowering species. Thus, early flowering species have low intraspecific variance in flowering times within a single growing season as individuals respond more uniformly to a common set of cues in comparison with late flowering species. However, these same species may show large variance between years reflecting interannual variation in climate.
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| 6. |
- Nilsson, Mats
(författare)
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Abundance and composition of plant biomass as potential controls for mire net ecosytem CO2 exchange
- 2012
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Ingår i: Botany. - 1916-2790 .- 1916-2804. ; 90, s. 63-74
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Tidskriftsartikel (refereegranskat)abstract
- We compared the amount and composition of different aboveground biomass (BM) fractions of four mires with their net ecosystem CO2 exchange (NEE) measured by eddy covariance. We found clear differences in response of green biomass (GBM) of plant functional types (PFTs) to water table (WT), which resulted in larger spatial variation in GBM within a mire than variation between mires. GBM varied between mires from 126 +/- 7 to 336 +/- 16 g.m(-2) (mean +/- SE), while within mire variation at largest was from 157 +/- 17 to 488 +/- 20 g.m(-2) (mean +/- SE). GBM of dominant PFTs appeared to be better in explaining the peak growing season NEE than the total BM or GBM of a mire. The differences in photosynthetic capacity between PTFs had a major role, and thus a smaller GBM with different species composition could result in higher NEE than larger GBM. Vascular plant GBM, especially that of sedges, appeared to have a high impact on NEE. Eleven PFTs, defined here, appeared to capture well the internal variation within mires, and the differences in GBM between communities were explained by the water table response of PFTs. Our results suggest the use of photosynthesizing BM, separated into PFTs, in modelling ecosystem carbon exchange instead of using just total BM.
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| 7. |
- Risberg, Lotta, et al.
(författare)
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Seed dynamics of two fire-dependent Geranium species in the boreal forest of southeastern Sweden
- 2012
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Ingår i: Botany. - 1916-2790 .- 1916-2804. ; 90, s. 794-805
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed critical life-history variables for two rare fire-dependent annual Geranium species in southern Sweden, which are today threatened because of effective fire suppression. At recently burned sites with abundant recruitment, seedlings occurred only where the humus layer had been completely removed by smoldering fire. Emergence depths ranged 1-6 cm in the mineral soil. Soil sampling at four sites revealed that in unburned soil Geranium seeds were located only in the mineral soil. Surprisingly, residual seeds were still present where fire had burned away the humus layer. An experiment showed that both species deposit seeds relatively evenly within a radius of 5-6 m, through ballistic dispersal. Repeated sampling in the field over a 2-year period after seed dispersal at one site indicated a low rate of seed depletion, corroborated by an indoor incubation of seeds. Our results show that successful management of these species depend on deep-burning prescribed fire, which can only result after severe drought. On the other hand, the seed bank is extremely long-lived, as viable seeds were present at a site last burned 200 years ago. This well-protected seed bank will likely buffer against both ill-timed fires and occasional failure in the recruiting seedling populations.
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| 8. |
- Rolstad, Jørund, et al.
(författare)
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Genetic variation and reproductive mode in two epiphytic lichens of conservation concern: a transatlantic study of Evernia divaricata and Usnea longissima
- 2013
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2790 .- 1916-2804. ; 91, s. 69-81
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Tidskriftsartikel (refereegranskat)abstract
- North European epiphytic lichens are often genetically impoverished compared with their North American counterparts.This has been hypothesized to impede sexual reproduction due to reduced chances of finding compatible mating typepartners. We compared genetic variation and reproductive mode in two threatened Scandinavian lichens, Evernia divaricata andUsnea longissima, with more viable populations in North America to see (i) if these species also show genetical depletion innorthern Europe and (ii) if the occurrence of sexual propagules (ascospores in apothecia) is more prevalent in genetically diversepopulations. Genetic variation of the fungal component was assessed by sequencing two nuclear rDNA gene regions (ITS and IGS)in 1005 and 1477 thalli, collected from 92 and 160 localities of E. divaricata and U. longissima, respectively. Scandinavian populationsof both species were almost devoid of genetic variation compared with much higher genetic diversity in North America.Wefound no support for the proposed relationship between genetic diversity and fertility. Fertile thalli were found in severalgenetically invariable populations. Fertility increased with population size and regional abundance in E. divaricata, but not inU. longissima. In Scandinavia, E. divaricata was more fertile than previously recorded, whereas all sampled populations ofU. longissima were sterile and possibly clonal.
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| 9. |
- Rosengren, Frida, et al.
(författare)
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Genetic variation in the moss Homalothecium lutescens in relation to habitat age and structure
- 2013
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Ingår i: Botany. - : Canadian Science Publishing. - 1916-2804 .- 1916-2790. ; 91:7, s. 431-441
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between genetic (allozyme) variation and landscape age and structure were investigated in 17 calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H. Rob. on the Baltic island of Oland. Mean within-deme gene diversity (H-S = 0.152) was moderate compared with other bryophyte studies, and the between-deme proportion of the total diversity (G(ST) = 0.100, Jost's D = 0.011) was low but significantly different from zero. Clonal mixing, measured as the proportion of two adjacent shoots having different haplotypes, was relatively high (mean 0.32 over all demes). HS was higher in old grassland fragments, but negatively related to vascular plant species richness. Allelic richness (A) was positively associated with the area of old (>= 280 years) grassland in the surroundings: although demes in old grasslands are genetically more variable than those in younger grasslands, proximity to large areas of old grassland may promote genetic variability even in younger grassland demes. The importance of management continuity for species diversity has been stressed in many earlier grassland studies. Here, we conclude that grassland fragments with a long history of grazing continuity are also positively associated with variability at within-species level, as exemplified by the bryophyte H. lutescens.
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| 10. |
- Samils, Berit
(författare)
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Alternate host ranges of Cronartium flaccidum and Cronartium ribicola in northern Europe
- 2012
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Ingår i: Botany. - 1916-2790 .- 1916-2804. ; 90, s. 694-703
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Tidskriftsartikel (refereegranskat)abstract
- Attached and detached leaves of 60 potential host species were inoculated in the greenhouse and laboratory with aeciospores of Cronartium ribicola J.C. Fisch. from six Finnish locations and of Cronartium flaccidum (Alb. & Schw.) Wint. from 20 locations in Finland and Sweden in 2011. Candidate hosts represented 16 plant families: Solanaceae, Verbenaceae, Asclepiadaceae, Grossulariaceae, Paeoniaceae, Balsaminaceae, Gentianaceae, Scrophulariaceae, Loasaceae, Tropaeolaceae, Acanthaceae, Myricaceae, Phrymaceae, Plantaginaceae, Orobanchaceae, and Apocynaceae. Inoculations of C. flaccidum produced uredinia after 2 weeks and (or) telia after 4 weeks of incubation on 25 hosts. Inoculation trials identified several new hosts for C. flaccidum in Fennoscandia, namely Impatiens balsamina, Swertia fedtschenkoana, Loasa tricolor, Myrica gale, Verbena canadensis, Saxifraga spp., Paeonia obovata, and Veronica daurica. Myricaceae and Saxifragaceae represent new host families for these rusts. Cronartium ribicola formed uredinia or telia on 10 species: Ribes spp. (7 species/cultivars), Pedicularis palustris subsp. palustris, Bartsia alpina, and Loasa triphylla. Results suggest wider alternate host ranges for both C. flaccidum and C. ribicola than previously recognized. Spores were virulent regardless of their source location, suggesting a lack of host-specificity among Fennoscandian populations of Cronartium.
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