Phytosociological and conservational study of the arable weed communities in western Hungary

The present study surveyed the weed vegetation on extensively managed arable fields and unsprayed field edges in western Hungary, based on 1698 phytosociological releves collected between 1995 and 2005. The separation of the 15 vegetation units was conducted with the traditional comparative tabular method, and the diagnostic species were determined with statistical fidelity measures. The numerical analyses show that the most important factor in the separation of weed communities is the fluctuating proportions of winter and summer annuals and cosmopolitan elements throughout the year. Soil chemical properties are the second most important whereas soil texture and climatic factors also contribute to the development of weed communities. The surveyed vegetation units support 41 red list weed species. Across all associations, the average proportion of insect-pollinated plant species is 68%, and the average proportion providing weed seed food sources for farmland birds is 47%. These factors illustrate the importance of weed communities in agro-ecosystem function and the need for their conservation.