Farming Intensity Affects Soil Seedbank Composition and Spontaneous Vegetation of Arable Weeds

Former studies carried out in the 2000s in the Lahn-Dill region located in the middle-east of the German state Hesse stated a depletion of arable weeds on the field scale and more diverse weed flora on the landscape scale. Current study, having started in 2018, aims to contribute to a better understanding of the interactions between arable weed species diversity, farming intensity, grown crops and landscape area. Moreover, the potential of organic farming methods for conservation and promotion the arable weed diversity is aimed to be assessed with the study. In total, 42 fields in two landscape regions were sampled—six seedbank samples were collected from each field; additionally, data on spontaneous arable weed flora were recorded each spring from 2019 to 2021; emerged aboveground weeds were identified in the fields and their coverage was documented. Four factors were considered in the field trial: Farming practice, landscape area, soil depth and the current crop. Effects of these factors on arable weed species diversity were calculated with a Generalized Linear Model (GLM), resulting in significant effects of the management system, the area and the current crop. Among the four organic farming systems that were sampled, the time period of organic growing had a significant effect on weed seed numbers in the soil with an increase in seed numbers. Average seedbank species numbers were around twice as high in organic farming systems (18 species) compared to conventional managed fields (nine species). Evidence of an ongoing species decline in the region on the landscape scale could be detected by comparison with a former study. Especially rare and endangered weed species are a concern due to seedbank and current vegetation depletion tendencies

Extensivierungsmaßnahmen im Ackerbau: Auswirkungen auf Flora, Vegetation und Samenbank - Ergebnisse aus dem Göttinger INTEX-Projekt

Seit 1990 werden in einem interdisziplinären Forschungsprojekt ("INTEX") die ökologischen und ökonomischen Auswirkungen verschiedener Extensivierungsmaßnahmen im Ackerbau untersucht. Auf drei Versuchsstandorten in Niedersachsen wurden in einer Rapsfruchtfolge zwei unterschiedliche Extensivierungsmodelle (integriert, extensiv) mit einem konventionellen Anbausystem verglichen. Daneben wurde eine selbstbegrünte Dauerbrache mit in die geobotanischen Untersuchungen über Flora, Vegetation und Samenbank einbezogen. Während im konventionellen System die Unkrautdeckungsgrade und das Artenspektrum gering blieben, nahmen im integrierten Anbausystem die Artenzahlen deutlich zu, ohne daß sich bisher seltene oder gefährdete Arten oder standortstypische Ackerwildkrautgesellschaften einstellten. Dies galt bisher auch für das extensive System mit dem völligen Verzicht auf Herbizide und mineralische Düngung, wobei hier die höchste floristisch-strukturelle Vielfalt aller verglichenen Segetalgesellschaften ermittelt wurde. Allerdings wird der hohe Naturschutzwert des extensiven Anbausystems durch eine zu starke Schwächung der Kulturpflanzen erkauft, die zu ökonomisch nicht tolerierbaren Ertragseinbußen führt. Typisch für die Ackerbrachen war zunächst die Massenentfaltung weniger Arten, bedingt durch die stark dezimierte Samenbank bzw. die Lage der Versuchsstandorte in der ausgeräumten Intensivagrarlandschaft. Mit fortschreitender Sukzession entwickelte sich eine standörtlich differenzierte, kleinräumig heterogene Vegetation mit hoher Arten- und Strukturvielfalt. Ein Vergleich der Samenbank zeigte nach dreijähriger Versuchsdauer für das konventionelle Anbausystem weiterhin einen stark dezimierten Samenvorrat, während sich im integrierten und extensiven System sowohl die Artenzahl als auch die Samenzahl deutlich erhöhten. Um ein Vielfaches höher als in den Anbausystemen war nach drei bzw. vier Brachejahren der Diasporenvorrat auf den Dauerbrachen. Er enthielt nicht nur erheblich mehr Arten, sondern unter den dominanten Arten auch einen höheren Anteil an Nicht-Ackerunkräutern als in den bewirtschafteten Systemen. Die Interessen von Landwirtschaft und Naturschutz lassen sich nach den vorliegenden geobotanischen Ergebnissen in Intensivagrarlandschaften am ehesten durch eine Verknüpfung des integrierten Anbausystems mit Dauerbrachen verwirklichen.Since 1990 an interdisciplinary research project ("INTEX") has been investigating the ecological and economical effects of extensification in arable systems. At three research sites in Lower Saxony two different extensification systems, namely integrated and extensive were compared to the conventional system for rotation of oilseed - rape crops. In addition to this, geobotanical investigations on flora, vegetation and soil seed bank were also carried out for a spontaneous old-field succession. Whereas weed coverage and species diversity remained limited in the conventional system, the number of species increased markedly in the integrated system. This took place without the appearance of rare or endangered plant species or of arable weed communities which had until now been characteristic for these landscapes. This pattern, up to now, had also applied to extensive systems with neither herbicide nor fertilizer application. Of the three agricultural weed communities compared, the highest floristical and structural diversity was ascertained for the extensive system. Despite the great importance of extensive systems for nature conservation, their value cannot compensate, in economic terms, for the weakening of crop plants and the resulting yield reductions. Typically, old-field succession was initially characterized by the mass development of those few species dependent on the reduced soil seed bank or on the location of the research sites in a poorly structured agricultural landscape with high-input farming. With progressive succession, a small-scale heterogeneous vegetation of high diversity in flora and structure developed, characteristic for the particular site conditions. After a period of three years the soil seed bank of the conventional farming system had remained limited. In the integrated and the extensive systems, however, not only the number of species but also the total number of seeds increased significantly. The soil seed bank of the old fields was many times greater than that of the arable systems after a period of three and four years. This applied not only to the total number of diaspores but also to the number of species included in the soil seed bank. In addition to this, the proportion of non-agricultural weeds increased considerably under set-aside conditions. The geo-botanical results presented in this paper suggest that the demands of both agriculture and nature conservation in intensively used agricultural landscapes could best be met by an integrated farming system in combination with abandoned old fields

Land-Use Change Related to Topography and Societal Drivers in High-Mountains – A Case Study in the Upper Watershed of the Tergi (Kazbegi Region), Greater Caucasus

High mountain ecosystems, with strong topographic and climatic gradients, are fragile and particularly sensitive to changes in land use. The abandonment of historic cultural landscapes has often led to changes in the pattern of land cover and thus, to a shift in the functions of high mountain landscapes, like fresh water supply, productivity or erosion control. In order to understand the effects of land-use change on the land-cover pattern at the local and regional scale, we analyzed and classified the mountainous landscape structure in the Kazbegi region in Georgia, located in the Central Greater Caucasus. For 13 settlements, we determined the land cover as present in 1987 and 2015, and quantified the changes over time to detect land-cover development trends for each settlement. Using a cluster analysis, the study area was analyzed regarding to topography (altitude, aspect, slope) and distance to settlements at the regional scale to gain six groups with separating conditions. Furthermore, each settlement was classified according to topography and land-cover change to obtain site-specific, comparative development trends. Our results show that this Caucasian high-mountain landscape is characterized by open grassland (67%) used as pasture and hay meadow, and natural birch forests (7%) in patches in the upper half of the subalpine belt. Within the settlements but also in their surroundings, field vegetables are cultivated in home gardens (1%). Land-cover change during the observation period mainly affected the cultural grassland with hay meadow abandonment. Moreover, shrubbery and forest expanded considerably on abandoned pastures. We further detected a strong relationship to topography that considerably varied between settlements resulting in specific trends in land-use change. Hay-making and arable land cultivation are focused today on sun-exposed and gentle slopes near the settlements. Shrub encroachment and reforestations were localized on farther distances and mostly on north-exposed slopes. Besides providing basic information about the historic and current land-use and land-cover patterns, our results quantify the landscape change during almost 30 years. A spatio-temporal analysis revealed an understanding of how land-use decisions influence the landscape pattern. In the context of societal development, regional socioeconomic processes, like shifts in the agricultural structure and population outmigration, seem to be societal drivers of changes. Our findings reveal linkages and interrelationships between natural, human-induced environmental and socioeconomic processes within high-mountain socio-ecological systems. Moreover, we suggest that sustainable land-use strategies for spatial development on sub-regional level, especially in marginal high-mountain regions, should consider topography and its influence on land-use change

The common pasture of the nature reserve “Kanzelstein bei Eibach” (Lahn-Dill Kreis, Hessen, Germany): Change and state of a biotope complex of a pre-industrial cultural landscape

Das Naturschutzgebiet „Kanzelstein bei Eibach“ ist ein Relikt der früher ausgedehnten Allmendeweiden des Dorfes Eibach (Stadt Dillenburg, Lahn-Dill-Bergland, Hessen). Die historische Nutzungsvielfalt, die sich bis in die frühindustrielle Zeit (um 1850) zurückverfolgen lässt, umfasste offene Bereiche, die vorrangig beweidet wurden, sowie Waldbereiche, in denen Bucheckern- und Eichelmast, die Schneitelung ausgewählter Baumarten sowie Niederwaldwirtschaft praktiziert wurden. Durch die über Jahrhunderte andauernde degradierende land- und forstwirtschaftliche Nutzung entwickelte sich ein kleinräumiges Mosaik aus Pioniergesellschaften (Airo caryophylleae-Festucetum ovinae), mageren Glatthaferwiesen (Arrhenatheretum hypochaeridetosum radicatae) und deren Versaumungsstadien, mesophilen Schlehengebüschen (Crataego-Prunetum spinosae), Hudewald- und Niederwaldformen des Hainsimsen-Waldmeister-Buchenwaldes (Galio odorati-Fagetum luzuletosum). Aufgrund der seit ca. 1960 aufgegebenen Nutzung sind die Nutzungs- und Vegetationsvielfalt durch Wiederbewaldung akut gefährdet. Zur Erhaltung und Entwicklung der Biodiversität des Naturschutzgebietes wird eine Wiedereinführung von Nutzungen in Anlehnung an das traditionelle Nutzungssystem empfohlen. Um ein Landschaftsbild zu entwickeln, wie es für 1959 rekonstruiert werden konnte, ist in den offenen Bereichen die kontinuierliche Weidenutzung mit Schafen und Ziegen und im Wald die Freistellung und -haltung der Schneitel- und Mastbäume unerlässlich.The nature reserve “Kanzelstein bei Eibach” is a remnant of the formerly extended common-land pastures of the village Eibach (City of Dillenburg, Lahn-Dill Highlands, Hesse, Germany). The historical diversity of resource utilisation, which can be traced back to early industrial times (1850), comprised, besides pastures, also forested areas. These were used as pasture woodland as well as for pollarding and coppicing. Degradation due to agricultural and silvicultural land-use practices for centuries led to the development of a mosaic of distinct plant communities. These comprise pioneer vegetation of dry-grasslands (Airo caryophylleae-Festucetum ovinae) and relatively nutrient-poor Tall Oat-Grass meadows (Arrhenatheretum hypochaeridetosum radicatae), each with their respective successional stages following abandonment. Additionally, the reserve features mesophytic blackthorn thickets (Crataego-Prunetum spinosae) and neglected coppice stands (Galio odorati-Fagetum luzuletosum). Forty years of nearly total abandonment, however, have resulted in an acute threat to species and vegetation types due to woodland succession. To conserve and restore the biodiversity of the nature reserve, it is necessary to re-establish land-use practices that follow the traditional management system. To recreate a landscape appearance that conforms to the situation prior to abandonment, which was reconstructed for 1959 by interpretation of aerial photographs, it is mandatory to re-establish a scheme of continuous sheep and goat grazing in the open areas. Maintenance measures on the remaining pollards and veteran trees should be carefully performed by cutting competitive woody species

Supply scale and demand for agricultural advisory services in Kosovo

The aim of the poster is to present the main findings of the research study on the supply scale and the demand of advisory services in the sector of agriculture in Kosovo. The study area covers ten municipalities and 120 farms coming from different sectors of agriculture. The data analyses show the supply scale of advisory services from 2007-2013; advisory sources, the importance of advisory services for farmers, and also identifies the methods and fields where these services should be focused in the future. Research findings show that almost half of the interviewed farmers did not receive advisory services and an interesting finding is that ten of the farmers did not her at all about these services. Farmers were drawing agricultural advices and services from different sources, where the highest percentage of offering advices for farmers was from private sector, specifically from different international organizations. The advisory services received from agriculture experts from public sector were significantly lower compared to the other sources. The derived results show that the advisory services were needed on all processes that accompany a farmer in agricultural production. In this regard the supply of advisory services in the future needs to be oriented mainly at pre-production phase, production, protection, processing, and marketing. Whereas, most favorable methods stressed by the farmers in receiving advisory services were oral advices, respectively experimental plots

Diversification des rotations de grandes cultures avec des prairies temporaires (un moyen pour combiner la gestion de la flore adventice et la conservation de la biodiversité)

La rotation de cultures peut être utilisée pour empêcher la sélection continue d espèces adventices adaptées à un type de culture. Elle pourrait favoriser la gestion des adventices, l économie d herbicides et la biodiversité. Les successions de cultures simples d aujourd hui pourraient être diversifiées par des cultures fourragères pérennes. Les impacts des ces cultures sur les adventices ont été étudié utilisant quatre approches : 1) Des relevés d adventices sur 632 champs dans l ouest de la France ont montré que la composition spécifique varie le plus entre des cultures fourragères pérennes et des cultures annuelles. Une comparaison des champs avant, pendant, et après des cultures fourragères pérennes a suggéré que la composition des communautés varie d une manière cyclique pendant ces rotations. Plusieurs espèces problématiques dans des cultures annuelles ont été supprimées pendant et après les cultures pérennes, mais l apparition d autres espèces a produit une diversité de plantes comparable, voire supérieure. 2) Une expérimentation au champ de trois ans avec des modes de gestion contrastés a permis d étudier les mécanismes sous-jacents: L absence de travail du sol a réduit la levée des adventices, mais a augmenté la survie des plantes adultes. Le couvert végétal permanent et les fauches fréquentes ont réduit la croissance, la survie des plantes et la production de graines. 3) Des expérimentations sous serre analysant la croissance poste fauche de plantes individuelles ont montré des différences importantes entre espèces et groupes fonctionnels. Une expérimentation à deux facteurs a suggéré que les impacts négatifs de la fauche et de la compétition sur la croissance des adventices ont été additifs. 4) Des mesures spéciales de prédation de graines d adventices sur l expérimentation au champ ont montré des corrélations positives avec le couvert végétal et la prédation, indiquant une importance particulière de ce service écosystémique dans des cultures pérennes. La préférence des graines de certaines espèces montre que la prédation de graines peut être une autre cause des changements de communautés d adventices.Crop rotation may be used to prevent the continuous selection of particular weed species adapted to one crop type. This might be useful for weed management, economy in herbicide applications and promoting biodiversity. Common simple crop sequences might be diversified by introducing perennial forage crops. Impacts of such perennial crops on weeds were studied with four approaches : 1) Large-scale weed surveys in 632 fields in western France showed that weed species composition differed most strongly between perennial alfalfa crops and annual crops. Comparisons of fields before, during and after perennial alfalfa suggested that community composition varies in a cyclic way during such crop rotations. Several weed species problematic in annual crops were suppressed during and after perennial crops, but the appearance of other species led to equal or even higher plant diversities. 2) A 3-year field experiment with contrasting crop management options allowed an investigation of the underlying mechanisms for this: The absence of soil tillage reduced weed emergence but increased the survival of established plants. The permanent vegetation cover and frequent hay cuttings reduced weed growth, plant survival and seed production. 3) Greenhouse experiments testing the regrowth ability of individual plants after cutting showed strong differences between species and functional groups. An two-factorial experiment suggested that the negative impacts of cutting and competition on weed growth were mainly additive. 4) Special measurements of weed seed predation in the field experiment showed positive correlations with vegetation cover, indicating that this ecosystem service may be particularly fostered by perennial crops. Consistent preferences of seed predators for certain weed species indicates that seed predation may be another cause of the observed weed community shifts.DIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Mapping Plant Functional Groups in Subalpine Grassland of the Greater Caucasus

Plant functional groups—in our case grass, herbs, and legumes—and their spatial distribution can provide information on key ecosystem functions such as species richness, nitrogen fixation, and erosion control. Knowledge about the spatial distribution of plant functional groups provides valuable information for grassland management. This study described and mapped the distribution of grass, herb, and legume coverage of the subalpine grassland in the high-mountain Kazbegi region, Greater Caucasus, Georgia. To test the applicability of new sensors, we compared the predictive power of simulated hyperspectral canopy reflectance, simulated multispectral reflectance, simulated vegetation indices, and topographic variables for modeling plant functional groups. The tested grassland showed characteristic differences in species richness; in grass, herb, and legume coverage; and in connected structural properties such as yield. Grass (Hordeum brevisubulatum) was dominant in biomass-rich hay meadows. Herb-rich grassland featured the highest species richness and evenness, whereas legume-rich grassland was accompanied by a high coverage of open soil and showed dominance of a single species, Astragalus captiosus. The best model fits were achieved with a combination of reflectance, vegetation indices, and topographic variables as predictors. Random forest models for grass, herb, and legume coverage explained 36%, 25%, and 37% of the respective variance, and their root mean square errors varied between 12–15%. Hyperspectral and multispectral reflectance as predictors resulted in similar models. Because multispectral data are more easily available and often have a higher spatial resolution, we suggest using multispectral parameters enhanced by vegetation indices and topographic parameters for modeling grass, herb, and legume coverage. However, overall model fits were merely moderate, and further testing, including stronger gradients and the addition of shortwave infrared wavelengths, is needed

Contrasting weed species composition in perennial alfalfas and six annual crops: implications for integrated weed management

International audienceWeed communities are most strongly affected by the characteristics and management of the current crop. Crop rotation may thus be used to prevent the repeated selection of particular weed species. While weed communities are frequently compared among annual crops, little is known about the differences between annual and perennial crops that may be included in the rotations. Moreover, nearly all existing studies (17 articles reviewed) are based on local field experiments rather than commercial fields. We compared the weed composition in perennial alfalfas (Medicago sativa) and six annual crops: winter wheat (Triticum aestivum), oilseed rape (Brassica napus), pea (Pisum sativum), sunflower (Helianthus annuus), maize (Zea mays) and sorghum (Sorghum bicolor) using data from 632 commercial fields in western France. Weed species composition showed the strongest dissimilarities between perennial alfalfas and all annual crops, followed by the well-known differences between autumn- and spring/summer-sown annual crops. Indicator Species Analysis showed that most weed species either preferred perennial alfalfas (including Taraxacum officinale, Veronica persica, Crepis spp., Poa trivialis, Silene latifolia, Capsella bursa-pastoris and Picris spp.) or annual crops (including Mercurialis annua, Galium aparine, Fallopia convolvulus, Chenopodium album and Cirsium arvense). Perennial alfalfas thus suppressed many weeds that are widespread (and sometimes problematic) in annual crops while favouring other species. Shifted weed composition and reduced frequency of several noxious weeds suggest that perennial alfalfas may be used as a valuable part of integrated weed management, reducing the need for herbicides and sustaining plant and animal diversity in agricultural landscapes