Abstract. Vegetation changes in a semi‐natural grassland of wooded meadow type that had been grazed for centuries are described following the introduction of various management regimes: mowing each year, mowing every third year, burning, mechanical removal of woody plants, chemical treatment of woody plants, continuous grazing and abandonment. The experiment was established in southern Sweden in 1972 and has been in progress for 15 years. In 1972, 1980 and 1986 the botanical composition in these plots was investigated in permanent subplots. The study clearly demonstrates that mowing or grazing is necessary to preserve community structure and that mowing is to be preferred in cases where maintaining species richness is of primary concern. Mowing every third year delayed vegetation change and prevented woody species from spreading. Therefore, periodic mowing might be an alternative way to preserve the flora. In contrast, yearly burning does not seem to be a viable management in this type of semi‐natural grassland. To preserve the open landscape regeneration of woody plants has to be prevented. However, in plots where woody plants were removed the typical grassland flora declined. Abandonment resulted in closed forest.

Abstract. The vegetation and soil seed bank in a limestone grassland in southern Sweden were studied in permanent 1‐m2 subplots which had been either grazed or not grazed for 17 yr. Of the 92 species recorded, 18 were present only in the seed bank, 28 were more frequent and 24 were less frequent in the seed bank than in the vegetation and 22 were not detected in the seed bank. Among the species present in the seed bank, therophytes were over‐represented. Species turnover in the vegetation was estimated from presence/absence data collected in 1980, 1986 and 1990. Turnover was high, but there were no differences between grazed and ungrazed subplots. The turnover for individual species was also high in many cases. There was no clear relationship between the turnover of a species and its presence in the persistent seed bank.

Summary 0[ Set!aside _elds have been an important element of the European agricultural landscape since the introduction of the set!aside scheme by the European Community[ However\ countries in the European Community di}er in their rules for managing set!aside owing to di}erent priorities[ 1[ In Sweden\ a major goal is to reduce the total use of agricultural pesticides\ consequently their use is prohibited in set!aside[ The options for weed control are therefore cutting and:or the use of a cover crop[ 2[ In this study\ we describe the course of succession following the abandonment of farmland managed in di}erent ways[ The~oristic composition was followed over a 09!year period[ Temporal trends in community development are described[ 3[ The experiment began in 0864 on farmland at six localities\ distributed from southern to northern Sweden[ The management treatments involving the application of fertilizers and cutting were applied to plots sown with a cover crop and to plots in which the succession started from bare ground[ 4[ We found that competitive interactions between species largely determined the successional course in our study[ The competitive success of species was related to the management practices applied but there were also interactions between management and site conditions[ 5[ We propose that natural succession can be recommended on poor sites in com! bination with cutting\ mainly to prevent the invasion of woody species[ On fertile sites a cover crop should be used to suppress perennial weeds\ and cutting is recommended mainly to increase species diversity[ Key!words] cutting\ fertilization\ long!term experiment\ old!_eld succession\ sec! ondary succession[ Journal of Applied Ecology "0887# 24\ 647Ð660

Bergkvist G, Adler A, Hansson M & Weih M (2010). Red fescue undersown in winter wheat suppresses Elytrigia repens. Weed Research50, 447–455. Summary Elytrigia repens (syn. Elymus repens) is a perennial grass weed that is controlled by herbicides or by tillage. Both methods are expensive and may have negative effects on the environment. Therefore, alternative methods of weed control, such as using competition from under‐sown perennial forage crops, are of interest. Red fescue can be sown together with winter wheat as a non‐flowering understorey crop that has its main growth during late summer and autumn. This study quantified the effect of red fescue and E. repens on wheat biomass and tested the hypothesis that under‐sown red fescue reduces the amount of E. repens rhizomes and thus the need for herbicides or tillage. Two field experiments in which winter wheat, red fescue and E. repens were grown in all possible combinations were conducted between 2003 and 2005. Elytrigia repens reduced wheat biomass by 8%, while red fescue had no significant effect on wheat biomass. Red fescue reduced late autumn biomass of E. repens rhizomes by 40%. The results suggest that red fescue sown with winter wheat can reduce propagation of E. repens during summer and autumn, without a significant reduction in wheat biomass.

No abstract

The influence of herbicides at reduced rates and repeated stubble-cultivation on weeds and crop yields was estimated in five field trials with spring-sown cereals situated in the south of Sweden during the autumn of 1989 until the spring of 1997. Stubble-cultivation was accomplished during 1989–1996, while herbicides were applied at 0, 1/8, 1/4 or 1/2 of full dose during 1990–1996.In the spring of 1997, i.e. after 7 years without herbicide application, seedling densities 3 weeks after weed emergence were 68–340/m2 at three sites and 535–610/m2 at two sites when averaged over tillage treatments.Averaged over herbicide doses, stubble-cultivation reduced the plant density of annual broad- leaved weeds by 6–32% at three sites and increased the density by 25% at one site. At the remaining site, the density was not significantly influenced. Stubble-cultivation reduced the populations of two perennial and seven annual weed species, while one species was stimulated and nine species showed null, or inconsistent, responses. In the spring of 1997, i.e. one year after the last herbicide application, the densities of weed seedlings in 1/8, 1/4 and 1/2-doses were 34, 46 and 56% lower, respectively, than in the untreated controls.Stubble-cultivation increased crop yields at four sites by 200 kg/ha as a mean over herbicide doses. At these four sites, averaged over 1993–1995, herbicides increased yields in plots that were not stubble-cultivated by 7, 8 and 10% in the 1/8, 1/4 and 1/2 of a full dose, respectively, relative to the untreated control. In 1996, herbicides increased yields at only two sites.It is concluded that a fruitful way for weed management with a low input of agrochemicals is to combine the use of herbicides at reduced rates with repeated stubble-cultivation.

Abstract. A semi‐natural grassland in Sweden was exposed to an elevated CO2 concentration during a six‐year open‐top chamber experiment. Vegetation composition was assessed twice a year using the point‐intercept method. The field had been grazed previously, but when the experiment started this was replaced with a cutting regime with one cut (down to ground level) each year in early August. From the third to the sixth year of the study the harvested material was divided into legumes, non‐leguminous forbs and grasses, dried and weighed. Elevated CO2 had an effect on species composition (as analysed by Principal Component Analysis) that increased over time. It also tended to increase diversity (Shannon index) in summer, but reduce it in spring. However, the effects of the weather and/or time on species composition and diversity were much more prominent than CO2 effects. Since the weather was largely directional over time (from dry to wet), with the exception of the fifth year, it was difficult to distinguish between weather effects and changes caused by a changed management regime. In all treatments, grasses increased over time in both mass and point‐intercept measurements, whereas non‐leguminous forbs decreased in mass, but not in point‐intercept measurements. Legumes increased in the point‐intercept measurements, but not in biomass, at elevated CO2, but not in the other treatments. Overall, we found that elevated CO2 affected species composition; however, it was only one of many factors and a rather weak one.

Anthriscus sylvestris (L.) Hoffm., is characteristic of productive habitats, and Festuca ovina of unproductive ones. The two species were grown at steady-state growth with either free access to all nutrients or severe nitrogen limitation. The maximum relative growth rate of the two species was similar -about 0.20 day -1. Root:shoot partitioning at nitrogen limitation differed between the species. A. sylvestris allocated less biomass to fine-roots than at free access and F. ovina allocated more.