Multiple regression analysis of data from field experiments conducted in Alberta at two locations between 1972 and 1983 indicated that there was a significant relationship between yield loss of barley (Hordeum vulgareL.) and wheat (Triticum aestivumL.) and relative time of emergence of wild oat (Avena fatuaL. ♯ AVEFA). At a given wild oat density, percent yield loss increased the earlier wild oat emerged relative to the crops and gradually diminished the later it emerged. However, the magnitude of the yield loss for both species varied with the year. Regression equations based on data pooled over years and locations were developed to provide an estimate of yield loss of barley and wheat due to relative time of wild oat emergence and wild oat density. The information should be considered when barley and wheat losses due to wild oat are being assessed.

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1. Worldwide, forest fragmentation induces edge effects, thereby strongly altering the forest microclimate and abiotic characteristics in the forest edge compared to the forest interior. The impact of edge-to-interior gradients on abiotic parameters has been extensively studied, but we lack insights on how biodiversity, and soil communities in particular, are structured along these gradients. 2. Woodlice (Isopoda) and millipedes (Diplopoda) are dominant macro-detritivores in temperate forests with acidic sandy soils. 3. We investigated the distribution of these macro-detritivores along forest edge-to-interior gradients in six different forest stands with sandy soils in northern Belgium. 4. Woodlouse abundance decreased exponentially with distance from the forest edge, whereas millipede abundance did not begin to decrease until 7 m inside the forest stands. Overall, these patterns were highly species specific and could be linked to the species' desiccation tolerance. Whereas the observed abundance patterns were independent from forest stand and dominant tree species, tree species had a large effect on community structure. 5. Edge gradients in macro-detritivores may consequently have implications for nutrient cycling, especially in smaller forest fragments with a large edge-to-interior ratio

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• Aims. Disentangling direct and indirect effects of global change drivers on plant nitrogen (N) uptake in leaves is important for understanding species and community responses in a changing world. • Methods. We created understorey herb communities on forest soils with and without recent agricultural history. We traced pulse additions of 15 NH4 15 NO3 within these mesocosms while applying two-level factorial treatments of N enrichment, warming and illumination. We modelled direct and indirect effects of treatments on leaf N content and 15 N uptake in leaves. • Results. Warming and illumination had three times larger direct negative effects on leaf N content per dry mass and percentage leaf N derived from label (NdAl%) than their indirect negative effects via an increasing community cover. These results imply a tissue dilution of N with increasing growth, in response to environmental change directly and indirectly exacerbated by community cover. We additionally found that interspeciAic differences in NdAl% correlated with a species' colonisation capacity and resource acquisition strategy. • Conclusions. Global change can directly affect allocation of N into foliage, with simultaneous indirect effects via altered community properties that inAluence individual plant responses. Predicting the future of plant communities in a changing world requires accounting for such understudied pathways.