Changement climatique ; Chine ; Cycle de l'azote ; Cycle du carbone ; Dégradation des sols ; Ecosystème ; Impact ; Montagne ; Plateau ; Propriétés du sol ; Qinghai ; Tibet
, climatic changes led to considerable degradation of alpine meadows and steppes : changes in soil physical properties; losses in soil available Fe, Mn and Zn; losses in soil organic matter and total nitrogen.
Patterns of soil organic carbon and nitrogen in relation to soil movement under different land uses in mountain fields (South Central Pyrenees)
Soil erosion and the global carbon cycle
Aragón ; Biogeochemistry ; Carbon ; Cultivated land ; Isotope analysis ; Land use ; Mountain ; Nitrogen ; Pyrénées ; Soil erosion ; Soil properties ; Spain ; Topography
was done in different parts of the slope to assess the pattern distribution of soil organic carbon (SOC) and nitrogen (SON). Other general soil properties analysed : pH, EC, carbonate content, grain size distribution and additional information derived from
. Under the land use practices in the studied fields the bottom slope positions accumulate soil particles and act as sinks of soil carbon and nitrogen in these mountain agricultural landscapes.
Assimilation de l'azote ; Association légumineuse-graminée ; Azote marqué N ; Compétition interspécifique ; Compétition intraspécifique ; Cycle biogéochimique ; Ecosystème ; Expérimentation ; Fixation de l'azote ; Graminée ; Géographie physique
Two types of plants (Trifolium pratense L. and Lolium multiflorum Lamk.) were grown in pots either separately, with one or two similar plants or together with one plant of each species. The use of labelled nitrogen N gives the proportion
of assimiled and (or) fixed nitrogen. Concurrence for N-nutrition is observed in monoculture for clover as well as for ryegrass. We confirm the order of N-mobilised quantities by plant: plant alone, two mixed plants, two similar plants. In association
forme. Le site, dans le N.W. de la région Pacifique des USA, est soumis à des pluies acides et à des apports élevés de soufre. En raison des relations biochimiques entre soufre organique et azote organique, le soufre en excès est accumulé et cyclé sous
Acidification ; Allemagne ; Bassin-versant ; Bayern ; Cycle de l'azote ; Ecologie ; Ecosystème ; Europe centrale ; Forêt ; Géosystème ; Nitrate ; Pollution ; Végétation
L'Institut de recherche sur les écosystèmes terrestres de Bayreuth étudie les bassins-versants boisés des montagnes du nord de la Bavière. Il s'intéresse en particulier au cycle de l'azote ainsi qu'à ses effets directs et indirects sur la végétation.
Examines nitrogencycling in rural catchments, placing particular emphasis on the delivery of nitrate to the stream system. Nitrate levels in UK freshwaters are reviewed. The possibility of controlling nitrate loss by managing land use is discussed
Concept ; Ecosystem ; Europe ; France ; Geochemistry ; Heavy metals ; Land use ; Micro-organism ; Nitrogencycle ; Plant canopy ; Salinisation ; Soil ; Soil erosion ; Soil pollution ; Soil properties ; Trace-element ; Tropical zone ; Water erosion
Concept ; Couvert végétal ; Cycle de l'azote ; Ecosystème ; Elément-trace ; Erosion des sols ; Erosion hydrique ; Europe ; France ; Géochimie ; Micro-organisme ; Métaux lourds ; Pollution du sol ; Propriétés du sol ; Salinisation ; Sol ; Utilisation
Carbon sequestration ; China ; Conifer ; Ecology ; Experimental station ; Model ; Nitrogen ; Plantation ; Southern China ; Subtropical zone
PnET-CN model describes the biogeochemical cycles of carbon (C) and nitrogen (N) and can assist in estimating carbon sequestration potential. For validation of PnET-CN, data from coniferous forest plantations in southern China was used. The results
Foliar nitrogen responses to the environmental gradient matrix of the Adirondack Park, New York
in controlling future nutrient cycling, and suggest that spatially explicit measurements of foliar N, environmental gradients, and plant resource strategies might provide a pathway to map and forecast ecosystem services at regional scales.
The organic soil layer (0-35 cm) of 17 sites under high altitude rocky complexes (HARC) was sampled in eastern Brazil, in the Espinhaço and Mantiqueira Ranges, to evaluate the relationship of vegetation type and carbon and nitrogen isotopic
composition of bulk soil and humic acid (HA). The majority of sites in the HARC presented a soil organic matter originated from C3-vegetation and demonstrated an intense N cycling based on the δ15N data. Even though charcoal could be suggested as a component
L'état de la question sur la modélisation des processus agro-écologiques dans la production agricole. Impact des engrais, fertilisants, pesticides sur les systèmes du sol, des eaux souterraines, des plantes cultivées. En particulier le cycle du
nitrogène et les cultures intensives sont étudiés. Modèles mathématiques de simulation pour les systèmes et programmation linéaire pour la gestion des systèmes d'exploitation figurent parmi les exposés des quatorze participants. (Vnm).