Search results for " forest"
showing 10 items of 1940 documents
Prediction of germination rates of weed species: Relationships between germination speed parameters and species traits
2011
International audience; In fields, the timing of weed emergence flushes is mostly related to the timing and rate of seed germination, which depend on seed dormancy level, soil temperature and water potential conditions as well as soil tillage and crop sowing date. Seed germination parameters are essential in weed dynamics models to account for the effects of soil conditions on weed demography. Since these parameters are difficult to measure, our objective was to test the possibility of estimating them from easily accessible information. Seed germination parameters (germination lag-time, time to mid-germination and mid-germination rate) were measured or collected from the literature for 25 w…
Seed bank dynamics of an invasive plant, Ambrosia artemisiifolia L.
2008
AbstractThe seed-bank dynamics ofAmbrosia artemisiifolia(Asteraceae), an annual invasive plant introduced from North America to Europe, were studied in nine French populations developing in field crops, set-asides or wastelands. The vertical distribution of seeds was studied in two different depth sections (0–5 cm and 5–20 cm), and the spatial horizontal pattern of distribution was analysed for two selected field-crop and set-aside populations. The proportions of dormant, non-dormant and dead seeds, as well as the changes in seed-bank dormancy over time, were evaluated. Natural seedling recruitment and its variation under different disturbance treatments in competitive set-asides were also …
Soil health through soil disease suppression: Which strategy from descriptors to indicators?
2007
International audience; Soil is a component of primary importance in crop production, even if it is often neglected, or only regarded as a physical support for the growth of plants. However, with the increasing societal concerns for the sustainability of agriculture, soil must be considered as a living system. Its quality results from the multiple interactions among physicochemical and biological components, notably the microbial communities, primordial for soil function. Crops are threatened by soil-borne diseases. These are often difficult to control, because of the “hidden” status of the pathogens and also because of the absence, noxiousness or lack of efficacy of chemical treatments. In…
Can we generate robust species distribution models at the scale of the Southern Ocean?
2018
17 pages; International audience; AimSpecies distribution modelling (SDM) represents a valuable alternative to predict species distribution over vast and remote areas of the ocean. We tested whether reliable SDMs can be generated for benthic marine organisms at the scale of the Southern Ocean. We aimed at identifying the main large‐scale factors that determine the distribution of the selected species. The robustness of SDMs was tested with regards to sampling effort, species niche width and biogeography.LocationSouthern Ocean.MethodsThe impact of sampling effort was tested using two sets of data: one set with all presence‐only data available until 2005, and a second set using all data avail…
Vermicompost from municipal sewage sludge affects growth and mineral nutrition of winter rye (Secale cereale) plants
2015
ABSTRACTThe aim of the study was to investigate sewage sludge vermicompost application effects on growth and mineral nutrition of winter rye (Secale cereale L.) plants as compared to two initial levels of mineral nutrient availability, pure sand and sand enriched with inorganic nutrients at the optimal level. Addition of sewage sludge vermicompost significantly inhibited rye seed germination at 20 to 50% sand substitution independently on mineral nutrient supplement. Growth inhibition was evident at early stages of plant development. However, at the later stages, sewage sludge vermicompost acted both as mineral fertilizer and plant growth-promoting agent. Significant stimulation of mineral …
Does an ant-dispersed plant, Viola reichenbachiana, suffer from reduced seed dispersal under inundation disturbances?
2008
Many plant species use ants as seed dispersers. This dispersal mode is considered to be susceptible to disturbances, but the effect of natural, small-scale disturbances is still unknown. We investigated how small-scale disturbances due to inundation affect seed dispersal in Viola reichenbachiana, a dominant myrmecochorous herb in riparian forests. Inundation disturbances were high in depressions and low on hillocks of the forest floor. We found that V reichenbachiana was similarly abundant at highly and less disturbed sites, contrary to other, non ant-dispersed species. We also found that the motivation of ants to disperse seeds was higher at highly disturbed sites. Nevertheless, the number…
An isoleucine-leucine substitution in chloroplastic acetyl-CoA carboxylase from green foxtail (Setaria viridis L. Beauv.) is responsible for resistan…
2002
The cDNAs encoding chloroplastic acetyl-CoA carboxylase (ACCase, EC 6.4.1.2) from three lines of Setaria viridis (L. Beauv.) resistant or sensitive to sethoxydim, and from one sethoxydim-sensitive line of Setaria italica (L. Beauv.) were cloned and sequenced. Sequence comparison revealed that a single isoleucine-leucine substitution discriminated ACCases from sensitive and resistant lines. Using near-isogenic lines of S. italica derived from interspecific hybridisation, we demonstrated that the transfer of the S. viridis mutant ACCase allele into a sethoxydim-sensitive S. italica line conferred resistance to this herbicide. We confirmed this result using allele-specific polymerase chain rea…
Effects of traditional coppice practices and microsite conditions on tree health in a European beech forest at its southernmost range
2016
Abstract: European beech (Fagus sylvatica) grows at the southern limit of its range in the mountain-Mediterranean vegetation belt up to the timberline. The southernmost beech forests of Sicily (southern Italy) show peculiar ecological, structural and silvicultural characteristics, growing in fragmented and isolated stands near the timberline and in topographically marginal unfavorable habitats. Past silvicultural practices increased the heterogeneity of stand structure at these sites. We compared stand structural characteristics and tree health in coppice-cut and control beech stands with respect to the local topographic gradient (bottom, slope and ridge) and canopy cover (clearing/border v…
Seedling growth of a native ( Ampelodesmos mauritanicus ) and an exotic ( Pennisetum setaceum ) grass
2016
Scarce information is available on the biological reasons why a small subset of introduced species can effectively establish within novel ecosystems. A comparison of early growth traits can help to explain the better performance of alien invasive species versus native co-occurring species. In one year-long experiment, we compared the early life stages of Ampelodesmos mauritanicus (Poir.) Dur. & Schinz (Amp), a native perennial Mediterranean grass, and Pennisetum setaceum (Forssk.) Chiov (Penn), an emerging invader grass in sub-arid and Mediterranean-climate areas. The Penn seedlings grew significantly faster and were approximately 2.5 times taller than the Amp seedlings, reaching a fina…
Effects of Arbuscular Mycorrhizal Fungi on the Vegetative Vigor of Ailanthus altissima (Mill.) Swingle Seedlings under Sustained Pot Limitation
2018
In order to invade new ecosystems, invasive alien plants need to cope with different microbial communities. Whilst the ability to avoid antagonists is well recognized, the opportunity to establish mutualistic associations is less known, even in widespread invasive species such as Ailanthus altissima (Mill.) Swingle. We sought to evaluate whether the beneficial effects of arbuscular mycorrhizal fungi (AMF) on Ailanthus seedlings are maintained over time, under prolonged pot limitation. We compared three-month-, three-year- and four-year-old mycorrhizal seedlings grown in natural forest soil (NT) with seedlings grown in sterilized (ST) and non-mycorrhizal (NM) soils, in pots of 3.4 L (22 &tim…