Indikatoren zur Erfassung genetischer Vielfalt in biologischen und nicht-biologischen Landwirtschaftssystemen

Genetic variability is the fundament of life. Large genetic variability within species is the basis for adaptation to changing environmental conditions. Farmers and breeders have developed a multitude of crop cultivars and animal breeds to stabilize and increase quality and productivity. This study evaluated genetic diversity within different organic and non-organic farming systems using crop-cultivar and livestock-breed information as simple indicators. Data was collected using on-farm surveys in 15 case study regions in Europe and beyond. Selected indicators revealed strong differences of cultivar diversity between different countries and farming systems across Europe. No or only small differences were detectable between organic and non-organic farming systems. Landraces, as on-farm genetic resources, were under-represented in European case study regions

BIOBIO – Indikatoren für Biodiversität in ökologischen und ex-tensiven Anbausystemen

Organic and low-input farming systems provide habitats for wildlife on farmland. The EU FP7 project BIOBIO has identified a core set of 23 indicators relating to the diversity of habitats, of species, of crops and of livestock. Management indicators capturing the pressure on biodiversity are also proposed. The indicators were identified in an iterative process between scientists and stake-holders to make sure that they are not only scientifically sound but also practicable and attractive. They were tested in 12 case study regions on four major farm types. Allocating 0.25 % of the CAP budget to a farm scale biodiversity monitoring would allow to measure and analyse the indicators on 50,000 farms across Europe

Gains to species diversity in organically farmed fields are not propagated at the farm level

Organic farming is promoted to reduce environmental impacts of agriculture, but surprisingly little is known about its effects at the farm level, the primary unit of decision making. Here we report the effects of organic farming on species diversity at the field, farm and regional levels by sampling plants, earthworms, spiders and bees in 1470 fields of 205 randomly selected organic and nonorganic farms in twelve European and African regions. Species richness is, on average, 10.5% higher in organic than nonorganic production fields, with highest gains in intensive arable fields (around +45%). Gains to species richness are partly caused by higher organism abundance and are common in plants and bees but intermittent in earthworms and spiders. Average gains are marginal +4.6% at the farm and +3.1% at the regional level, even in intensive arable regions. Additional, targeted measures are therefore needed to fulfil the commitment of organic farming to benefit farmland biodiversity

Farmland biodiversity and agricultural management on 237 farms in 13 European and two African regions

Farmland is a major land cover type in Europe and Africa and provides habitat for numerous species. The severe decline in farmland biodiversity of the last decades has been attributed to changes in farming practices, and organic and low-input farming are assumed to mitigate detrimental effects of agricultural intensification on biodiversity. Since the farm enterprise is the primary unit of agricultural decision making, management-related effects at the field scale need to be assessed at the farm level. Therefore, in this study, data were collected on habitat characteristics, vascular plant, earthworm, spider, and bee communities and on the corresponding agricultural management in 237 farms in 13 European and two African regions. In 15 environmental and agricultural homogeneous regions, 6–20 farms with the same farm type (e.g., arable crops, grassland, or specific permanent crops) were selected. If available, an equal number of organic and non-organic farms were randomly selected. Alternatively, farms were sampled along a gradient of management intensity. For all selected farms, the entire farmed area was mapped, which resulted in total in the mapping of 11 338 units attributed to 194 standardized habitat types, provided together with additional descriptors. On each farm, one site per available habitat type was randomly selected for species diversity investigations. Species were sampled on 2115 sites and identified to the species level by expert taxonomists. Species lists and abundance estimates are provided for each site and sampling date (one date for plants and earthworms, three dates for spiders and bees). In addition, farmers provided information about their management practices in face-to-face interviews following a standardized questionnaire. Farm management indicators for each farm are available (e.g., nitrogen input, pesticide applications, or energy input). Analyses revealed a positive effect of unproductive areas and a negative effect of intensive management on biodiversity. Communities of the four taxonomic groups strongly differed in their response to habitat characteristics, agricultural management, and regional circumstances. The data has potential for further insights into interactions of farmland biodiversity and agricultural management at site, farm, and regional scale

Approche multidimensionnelle de la typologie et de la cartographie des stations à pin d'Alep de la région de Touiref (Tunisie septentrionale)

Doctorat en Sciences agronomiques -- UCL, 199

Modélisation de la croissance en hauteur dominante et fertilité des peuplements de pin d’Alep (Pinus halepensis Mill.) en Tunisie

The Aleppo pine (Pinus halepensis Mill.) is a rustic species, very present in Mediterranean regions (Pardé J. 1957 ; Quezel P. 1986 ; Mezali M. 2003). Representing more than 56% of the total forest area (Sghaier 2005), this species is of a great economical, ecological and social values in Tunisia. The development of management models for various area of this species is currently one of the first priorities of the forest administration in the country. It is within this framework that an integrated study on Aleppo pine was undertaken in Tunisia by installing 348 temporary plots with a circular of 400 m2 each. These plots were set in such a way to cover the whole distribution area of the species in the country, from the arid to sub-humid bioclimates. To choose a model which describes the dominant height growth according to the age and to identify the sites quality relating to this species, varied mathematical models with common asymptote, based on the difference equations method (Table 1), were adjusted and compared. The difference equations method supposes that the observations on a given plot should belong to the same site index curve. The dominant height H 2 measured at the age t 2 is expressed as a function of t 2 , the height H 1 measured at the age t 1 , and t 1 . The expression is obtained by the substitution of one parameter in the growth model height-age (Elfving and Kiviste 1997). The data, which were used for the different adjustments, come from the stem analyses. To estimate the parameters of the various tested models, we performed a non-linear regression using the NLIN procedure of SAS software. A certain number of criteria were used to compare these models (Table 2). These criteria are based on the value and the distribution of the residues and the relation between the observed and estimated values. After analysis, it appeared that the polymorphic difference equation derived from the Lundqvist-Korf function resulted in the best compromise between biological and statistical aspects, producing the most adequate site index curves. This equation is as follows : [FORMULA] where H 1 is the height (m) at age t 1 (years), H 2 is the height (m) at age t 2 (years). Thanks to this model, the various Aleppo pine stands in Tunisia were divided into 4 classes of quality or productivity. These classes are characterized by average dominant heights obtained at 50 years age of 13,5 m ; 10,5 m ; 7,5 m and 4,5 m, respectively for the first, second, third and fourth class of quality.Pour caractériser la croissance en hauteur dominante du pin d’Alep (Pinus halepensis Mill.) en Tunisie, différents modèles issus des équations différentielles de Sloboda et McDill-Amateis, ainsi que de la forme intégrale de Chapman-Richards, Lundqvist-Korf et Logistique, ont été ajustés et comparés. Les données utilisées pour la modélisation sont issues de 348 analyses de tiges d’arbres abattus, soient 1 274 couples hauteur-âge mesurés sur des placettes temporaires distribuées sur toute l’aire de répartition de l’espèce dans le pays. Des analyses qualitatives basées sur le réalisme biologique des modèles, aussi bien que des analyses numériques et graphiques basées sur la précision des modèles ont été employées pour comparer les différents modèles testés. L’équation polymorphique en différences algébriques dérivée de la forme intégrale de la fonction de Lundqvist-Korf a donné le meilleur compromis entre les aspects biologique et statistique, fournissant les courbes de croissance les plus adéquates. Cette équation invariable quant à l’âge de base a permis de répartir la pinède tunisienne en 4 classes de qualité. La première classe de qualité est caractérisée par des hauteurs dominantes à l’âge de 50 ans de 12 m et plus. La deuxième classe possède des hauteurs dominantes au même âge comprises entre 9 et 12 m. La troisième classe englobe les peuplements dont les hauteurs dominantes à l’âge de référence varient entre 6 et 9 m, et finalement la quatrième et dernière classe de qualité dont les hauteurs dominantes ne dépassent pas les 6 m. Environ la moitié des peuplements échantillonnés appartient à la troisième classe.Sghaier Tahar, Garchi Salah. Modélisation de la croissance en hauteur dominante et fertilité des peuplements de pin d’Alep (Pinus halepensis Mill.) en Tunisie. In: Ecologia mediterranea, tome 35,2009. pp. 49-63

Growth and dendrometric relationship of stone pine (Pinus pinea) planted in the coastal dunes of North Tunisia

Format du poster : A0absen

Natural regeneration of Pinus pinea L. in Tunisia as influenced by canopy cover, litter biomass and understory vegetation

Forest and Landscape Working Papers N°35-2009absen

Contribution @ l' tude floristique phyto- cologique et dynamiquede la pin(de de Sakiet (Tunisie Septentrionale)

BSE B226564X / UCL - Université Catholique de LouvainSIGLEBEBelgiu