Search results for " zero"
showing 10 items of 1421 documents
Coping with Difficult Weather and Snow Conditions : Reindeer herders’ views on climate change impacts and coping strategies
2016
Winter is a critical season for reindeer herding, with the amount and quality of snow being among the most important factors determining the condition of reindeer and the annual success of the livelihood. Our first aim was to model the future (2035–2064) snow conditions in northern Finland, especially the quantities related to ground ice and/or ice layers within the snow pack, exceptionally deep snow and late snow melt. Secondly, we studied the strategies by which herders cope with the impacts of difficult weather and snow conditions on herding by interviewing 21 herders. SNOWPACK simulations indicate that snow cover formation will be delayed by an average of 19 days and snow will melt 16 d…
Social process of adaptation to environmental changes: How eastern african societies intervene between crops and climate
2014
Abstract Studies on climate change can only be conducted on a long time scale, and observing how societies adapt their sowing practices to climate variability is challenging and costly. As an alternative, a space and time substitution design was used, changes in space corresponding to that induced in time by environmental change. On the eastern slope of Mount Kenya, the Tharaka community, originating from the lowlands (750 m), moved up to the midlands (950 m) with their lowland-adapted resources, whereas the Mwimbi, originating from wetter upland (1100 m), moved down to the midlands with their highland-adapted genetic resources. A weather station was installed at 950 and 1100 m, and a logis…
Plant diversity effects on aboveground and belowground N pools in temperate grassland ecosystems: Development in the first 5 years after establishment
2011
[1] Biodiversity is expected to improve ecosystem services, e.g., productivity or seepage water quality. The current view of plant diversity effects on element cycling is based on short-term grassland studies that discount possibly slow belowground feedbacks to aboveground diversity. Furthermore, these grasslands were established on formerly arable land associated with changes in soil properties, e.g., accumulation of organic matter. We hypothesize that the plant diversity-N cycle relationship changes with time since establishment. We assessed the relationship between plant diversity and (1) aboveground and soil N storage and (2) NO3-N and NH4-N availability in soil between 2003 and 2007 in…
Insect Vectors (Hemiptera: Cixiidae) and Pathogens Associated with the Disease Syndrome “Basses Richesses” of Sugar Beet in France
2019
International audience; The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. leporinus was considered to be the economic vector of SBR disease. C. wagneri, the prim…
A simple modelling of crop water balance for agrometeorological applications
1991
Abstract A simple agrometeorological model of crop water balance is presented. It aims at the best estimate possible of the water balance components with the simplest formulation and the minimum set of input data. The model works with a time step of one day and uses rainfall and the calculated evapotranspiration as the climatic inputs. Some soil and crop characteristics, such as the maximum available moisture and crop coefficients are required as input parameters. The model is tested using experimental data obtained on wheat and lucerne crops in the Paris region. The sensitivity of the model is discussed and some possible applications to rainfed crop management are presented.
GrassPlot – a database of multi-scale plant diversity in Palaearctic grasslands
2018
GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (relevés) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001; ... 1,000 m²) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes a…
Does plant diversity influence phosphorus cycling in experimental grasslands?
2011
Plant diversity was shown to influence the N cycle, but plant diversity effects on other nutrients remain unclear. We tested whether plant species richness or the presence/absence of particular functional plant groups influences P partitioning among differently extractable pools in soil, P concentrations in soil solution, and exploitation of P resources (i.e. the proportion of total bioavailable P in plants and soil that was stored in aboveground biomass) by the plant community in a 5-year biodiversity experiment in grassland.The experimental grassland site established in 2002 had 82 plots with different combinations of numbers of species (1, 2, 4, 8, 16, 60) and functional groups (grasses,…
Response and effect traits of arable weeds in agro-ecosystems: a review of current knowledge.
2017
25 pages; International audience; Integrating principles of ecological intensification into weed management strategies requires an understanding of the many relationships among weeds, crops and other organisms of agro-ecosystems in a changing context. Extensively used during the last two decades in weed science, trait-based approaches have provided general insights into weed community response to agricultural practices, and recently to understanding the effect of weeds on agro-ecosystem functioning. In this review, we provide a holistic synthesis of the current knowledge on weed response and effect functional traits. Based on the literature and recent advances in weed science, we review cur…
Assessing the role of megafauna in tropical forest ecosystems and biogeochemical cycles - the potential of vegetation models
2018
21 pages; International audience; Megafauna (terrestrial vertebrate herbivores > 5 kg) can have disproportionate direct and indirect effects on forest structure, function, and biogeochemical cycles. We reviewed the literature investigating these effects on tropical forest dynamics and biogeochemical cycles in relation to ecology, paleoecology, and vegetation modelling. We highlight the limitations of field‐based studies in evaluating the long‐term consequences of loss of megafauna. These limitations are due to inherent space‐time restrictions of field‐studies and a research focus on seed dispersal services provided by large animals. We further present evidence of a research gap concerning t…
Potential of Crotalaria species as green manure crops for the management of pathogenic nematodes and beneficial mycorrhizal fungi
2004
On the basis of preliminary experiments, some Crotalaria species from Senegal were investigated to determine (1) their susceptibility to Meloidogyne javanica and M. incognita compared to a sensitive host (tomato), (2) their mycorrhizal and rhizobial responses, and (3) the effect of their cultivation on the mycorrhizal soil infectivity. The nematode invasion rates on Crotalaria spp. ranked from 0.17 to 7.17% and from 0.58 to 5.25%, respectively, for M. incognita and M. javanica, vs. 97% and 77% on tomato. Moreover, the inoculated J2 which invaded tomatoes developed into adult females, while those on Crotalaria spp. rarely developed beyond the third stage, confirming that all Crotalaria spp. …