Senecio Sylvaticus Research Articles

The influence of site conditions on Senecio sylvaticus seasonal abundance, soil moisture dynamics, and Douglas-fir seedling water stress

The influence of site conditions on Senecio sylvaticus seasonal abundance, soil moisture dynamics, and Douglas-fir seedling water stress

Repeated, high-severity wildfire catalyzes invasion of non-native plant species in forests of the Klamath Mountains, northern California, USA

Non-native plant invasions are often catalyzed by wildfires and may alter the structure, function, and composition of ecosystems. Of particular concern are non-native annual grasses that promote increased fire frequency and compete with native vegetation for early season moisture. While these effects are well studied in non-forested ecosystems, relatively few studies document invasions of non-native annual grasses in forested ecosystems. We document non-native plant invasion following repeated high-severity wildfire in mixed-conifer/hardwood forests dominated by Douglas-fir (Pseudotsuga menziesii) in the Klamath Mountains of northern California. Despite great concern regarding the loss of conifer dominance and transitions to non-forested states related to recent and projected increases in wildfire activity, there is little known about invasions of non-native plant species following fire in this region. Non-native plant species capable of long-distance dispersal had an average total cover of 26% and were ubiquitous across a systematic, gridded sample of twenty 800 m2 plots. Non-native forbs included multiple species of common post-disturbance invaders (e.g. Cirsium vulgare, Senecio sylvaticus, Lactuca serriola). Non-native annual grasses comprised more of the vegetative cover than non-native forbs (17% vs. 9%), and were dominated by two species, Aira caryophyllea and Vulpia myuros, which reached as high as 80% cover. Our findings indicate that non-native annual grasses are a novel stressor that may accelerate projected loss of conifer dominance in the Klamath Mountains by facilitating fire spread and increasing competition for early season soil moisture. Additional monitoring will be crucial to understanding the impacts of non-native plants as fire activity in this region continues to increase.

Presence of Senecio sylvaticus L. (Asteraceae) in Turkey

Abstract The annual plant Senecio sylvaticus L. (Asteraceae) is regarded as a doubtfully recorded in Turkey. It has not been collected in the country since the first report of its occurrence in the north eastern Black Sea Region in 1875. This paper reconfirms the occurrence of Senecio sylvaticus in Turkey. New specimens were collected from the Ereğli and Alaplı regions (Zonguldak province, NW Turkey) in 2014. The species description, distribution maps and photographs are given.

Effects of soil acidification and liming on ground flora establishment after clear-felling of Norway spruce in Sweden

We used 2 long-term field experiments with Norway spruce Picea abies (L.) Karst. to investigate the influence of lime, acid sulphur compounds, or nitrogen (1 site) on the rate of recruitment of new vascular species after clear-fellings. On the study sites, Farabol in southern Sweden and Fäxboda in south–central Sweden, the chemical treatments had been applied before clear-felling and whole-tree harvesting. An additional, post-harvest experiment was conducted at Farabol in which lime, hardened wood-ash, or logging residues were applied. A germination experiment including seven species was carried out in a greenhouse using sifted humus from Fäxboda that was sampled 2 years before clear-felling. The clear-fellings resulted in establishment of many ephemeral species. The number of newly established species was greater than the number of disappeared species. There was an overall positive correlation with pH in the humus layer and the number of newly established species. The treatment effects differed between the sites, probably reflecting differences in total dose and initial soil conditions. Farabol is characterised by more acid soils and greater atmospheric deposition of S and N than Fäxboda. At Farabol, liming (in total 6000 kg limestone ha −1 distributed over 12 years) resulted in about 20 new species established after clear-felling, four times more species than in untreated, sulphur-treated, or nitrogen-fertilised plots. At Fäxboda, where lime (2000 kg dolomite ha −1), sulphuric acid, and elementary S had been applied 16 years before clear-felling, the number of newly established species was about 15, and no effect of the treatments was revealed. The post-harvest treatments at Farabol showed that wood-ash and logging residues had similar effects as lime on the establishment of new species. The pot experiment showed that liming or acidification can affect the germination of seeds. Compared with untreated soil, a greater proportion of seeds of Primula veris ( P. veris) and Senecio sylvaticus ( S. sylvaticus) germinated in limed soil and the germination of P. veris was lower in acid- or sulphur-treated soils. The germination of Vaccinium myrtillus ( V. myrtillus) seeds was negatively affected by liming. No effects of the treatments were discovered on the germination of Deschampsia flexuosa, Calamagrostis arundinacea, Galeopsis bifida ( G. bifida), or Poa nemoralis. The soil water in the pot experiment had higher pH, higher concentrations of Ca and Mg, and higher NO 3 −/NH 4 + ratios in limed soil compared with other treatments. Nomenclature of plants follows Lid (1985).

Effects of phenolic acids on germination and early growth of herbaceous woodland plants

Four herbaceous plant species from woodland (clearings),Deschampsia flexuosa, Scrophularia nodosa, Senecio sylvaticus, andChamaenerion angustifolium, were tested for their sensitivity to phenolic acids. Seven commonly occurring phenolic compounds were used in a germination experiment in concentrations ranging from 0.01 to 10 mM, i.e., salicylic,p-hydroxybenzoic, syringic, caffeic, vanillic,p-coumaric, and ferulic acids. Germination was delayed rather than inhibited. Radicle elongation was strongly affected; at lower concentrations stimulatory effects were observed, whereas at high concentrations radicle elongation was severely reduced. Salicylic acid was the most effective phenolic compound, whereas caffeic acid caused no effects. Early growth was studied in more detail in a second experiment withDeschampsia flexuosa andSenecio sylvaticus and the phenolic acids, ferulic and p-coumaric acid. Primary root length, number and length of secondary roots, and dry weight were stimulated at 0.01 mM but were inhibited at 10 mM of both compounds. The results are discussed in view of the allelopathic relations between trees and herbaceous understory vegetation.

PHENOLIC SUBSTANCES IN A HUMUSPODZOL PROFILE AND THEIR IMPACT ON SOME WOODLAND HERBS AT LOW NUTRIENT SUPPLY

Twelve years after clearance of a Picea abies stand, the spectrum of water-soluble phenolic acids in the soil still resembled that of an adjacent, undamaged stand. Ferulic and p-coumaric acid were the predominant phenolic compounds. Apparently, the spectrum of low molecular phenolics in the soil layers is affected by the original litter material over a long period. The concentrations of water-soluble acids was highest in the A0-horizon. A comparison between the sites revealed that concentrations in the clearing were reduced with more than 50% compared to the undamaged stand. The significance of the phenolic acids for plant growth was investigated for two herbaceous woodland (-clearing) species, Senecio sylvaticus and Chamaenerion angustifolium. Both species were tested for their sensitivity to phenolic acids in dependence of nutrient supply under greenhouse conditions. Severe growth reduction occurred at high phenolic acid concentrations (10–3 M). Plants that were restricted in growth by a low nutrient supply, were less affected by the intermediate phenolic acid concentrations of 10–5 and 10–4 M than plants grown at high nutrient supply. The results are discussed in view of vegetation succession on woodland clearings.

Replacement of Sodium and Potassium in a Natrophobe and a Natrophile Senecio Species

Summary Uptake and translation of mineral nutrients and transpiration rates of a so-called natrophile, Senecio sylvaticus, and a so-called natrophobe, Senecio viscosus, have been studied in sodium/potassium replacement series. Simultaneous increase of sodium and decrease of potassium affected the growth of S. sylvaticus more than that of S. viscosus. Difference in sodium sensitivity was not related to transpiration rates and water economy. The diminished growth could be correlated with an increase of sodium in all plant organs. This increase was stronger in S. sylvaticus than in S. viscosus and gave rise to higher concentrations of magnesium, zinc and calcium. Changes in the Mg/Ca- and K/Na-ratio are discussed as the main metabolic disturbance responsible for growth reduction.

Differential Changes in Isoenzyme Pattern of 6-Phosphogluconate Dehydrogenase in Individual Plants of Senecio sylvaticus L. during Development

The isoenzyme patterns of individual plants from a population of the annual Senecio sylvaticus was determined at four stages of development, i.e. small rosette stage, large rosette stage, shooting stage and flowering stage, by gelelectrophoresis. Changes of isoenzyme pattern occurred only in 6-phosphogluconate dehydrogenase, the other six enzymes tested, remained constant throughout life cycle. The isoenzymes of 6-phosphogluconate dehydrogenase were compartmentated in the cytosol and chloroplast. With ageing activity of the isoenzymes in the chloroplast decreased and that of those in the cytosol increased.

Growth and mineral nutrition of plant species from clearings on different horizons of an iron-humus podzol profile.

Four plant species of woodland clearings - Avenella flexuosa, Chamaenerion angustifolium, Rumex acetosella, and Senecio sylvaticus - were grown on five different horizons of an iron-humus podzol profile. Reasonable growth was achieved only on the A0 horizon, which was rich in organic matter. The growth reduction on the other horizons was correlated with low concentrations of manganese and phosphorus in soils and plant organs. The restriction of so-called acidophilous species to acid soils is interpreted as meaning that they have a need for a high supply of manganese.

Nutritional status of soil and plant species in several clearings in coniferous woods compared to that in two related habitats

The nutritional status of the soils of a series of coniferous woodland clearings in the Netherlands was found to be intermediate between that of the soil in a dune area with a climax population of Chamaenerion angustifolium and that of the edge (and undergrowth) of a Quercus robur stand. In the dune area the greater part of the NPK was present as an internal pool in the plant tissues of C. angustifolium enabling the population of this species to persist and inhibiting further succession through limiting the availability of NPK. It is suggested that succession in clearings might stagnate in the same way in the absence of new tree growth. Because C. angustifolium is capable of persisting as a population under poor N conditions, it is unsuitable as an indicator species for nitrate-rich soils. The same may be true for Senecio sylvaticus, the other character species of the association Epilobio-Senecionetum sylvatici.

Senecio Sylvaticus in Relation to Douglas‐Fir Clear‐Cut Succession in the Oregon Coast Range

Senecio sylvaticus is a northern European adventive which has adapted well to a short term dominance at the beginning of secondary succession on slash—burned class—cuts in the Douglas—fir region. The species time—space niche is related to its copious production of small pappus—borne cypselas, low competitive ability, and apparent high soil—fertility requirements associated with the release of minerals directly following slash burning.

Comparative response of closely related species to reduced competition. I. Senecio sylvaticus and S. viscosus

A comparison of the reproductive and vegetative responses of Senecio sylvaticus and Senecio viscosus to the time and intensity of reduced competition is reported. The two species reacted similarly to thinning in terms of (1) reduced seed production per experimental population and increased seed production per individual, (2) reduced head production, (3) reduced vegetative dry weight, and (4) increased plant height.The two species of Senecio differed in their reaction to thinning in terms of (1) initial anthesis, (2) number of seeds per head, and (3) mortality. Thinning had no significant effect in altering the initial flowering of S. sylvaticus. Early thinning in S. viscosus advanced the flowering date while late thinning delayed flowering. S. sylvaticus was capable of increasing the number of seeds per head only if thinning occurred early, whereas the number of seeds per head in S. viscosus significantly increased at all thinning periods. Lastly, S. sylvaticus experienced much heavier mortality than S. viscosus.

Competition in Experimental Populations of Weeds with Emphasis on the Regulation of Population Size

Several factors, singly or synergistically, may influence the behavior of weedy species under conditions of intraspecific competition. The species studied were Bromus inermis, B. tectorum, Capsella bursa—pastoris, Conyza canadensis, Plantago lanceolata, P. major, Senecio sylvaticus, S. viscosus, and Silene anglica. Some or all of the species were subjected to conditions of intraspecific competition involving variable regimes of: (1) seed—sowing density, (2) soil surface, (3) fertilizer, (4) moisture, and (5) habitat, i.e., greenhouse and non—greenhouse conditions. Initially the vegetative dry weight production per unit area increased as density increased for every species. After a certain density (relative to the species) was reached, production was independent of density. All species displayed considerable plasticity in that similar genotypes showed a great increases in seed production between high and low densities (e.g., over a 100—fold increase for Capsella bursa—pastoris). Mean seed weight was constant under variable conditions of density, fertilizer, soil surface, and moisture in al species except Bromus tectorum. In mixed stands, the population of each species is smaller than its potential maximum. The size of the population of seedlings may be determined by the number of microenvironments suitable for germination (safe—sites) in an area. The populations of the respective species may be further regulated by: (1) self—controlled germination (Bromus inermis, Conyza canadensis, Plantago lanceolata, and Silene anglica); (2) mortality (Plantago major); and (3) individual plasticity (Bromus tectorum, Capsella bursa—pastoris, Senecio sylvaticus, and S. viscosus).